recursal/Fanatic-Fandom huggingface dataset:
Atlantic/2018/04L/Archive/5

Tropical Storm Debby Discussion Number 5

Wiki-Hurricanes Forecast Center

11:00 AM AST Wed Aug 8 2018

The tropical transition of Debby this morning was quite unexpected given the system's latitude above 40°N latitude. In fact, it took me a moment to verify that this morning's satellite imagery for Debby was in fact Debby. Perhaps this should not be too surprising given that lapse rates were quite high with a deep layer thermal differential in excess of 80°C, so it appears that Debby has cold tropopause temperatures to thank for its tropical transition. Visible and infrared pictures from this morning show a well-defined spiral circulation, which at one point showed a fairly classic primordial curved band structure, with 1006Z microwave data from SSMIS showing some early banding features. Raw UW-CIMSS ADT values have climbed once again to T2.8/42kt, in agreement with TAFB yielding T3.0/45kt. SAB appears to be a low outlier with their T1.0/25kt estimate. Scatterometer data are more in agreement with the higher values, and a blend between the two higher values indicates an intensity of 45 kt.

Debby is not expected to last very long as a tropical system. The tropical storm is currently moving north in response to an approaching shortwave trough over Newfoundland and Labrador. Debby should turn towards the northest before the trough absorbs the tropical storm as anticipated by model guidance. During the course of the day today, Debby should be able to maintain its intensity thanks to divergent flow aloft and a deep-layer thermal differential peaking as high as +81.8°C, supportive of good convective activity. Still, there is little Debby can do before absorption occurs in an estimated 36 hours.

FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 45 KT 50 MPH

12H 09/0000Z 45 KT 50 MPH

24H 09/1200Z 40 KT 45 MPH

36H 10/0000Z...DISSIPATED
Atlantic/2019/08L/Archive/17

Gabrielle has organized this evening as convection wraps fully around the low-level circulation, resembling an eye-like feature. In addition, a spiral band is in the process of developing across the western and southern semicircles. Satellite intensity estimates from CIMSS ADT and TAFB were around T3.0/45kt, and an evening ASCAT pass confirmed this number as well. Therefore, the initial intensity remains unchanged.
Originally, Gabrielle was expected to be reaping the benefits of a low wind shear environment right now. Instead, the favorable upper-level pattern has not materialized, and moderate to strong shear of 15-20kt continues. Thus, despite anomalously warm ocean temperatures, only gradual intensification is expected. The storm's peak has again been decreased from the previous advisory, as confidence in Gabrielle reaching hurricane intensity has decreased. After 36 hours, rapidly-cooling water temperatures and non-tropical features will cause Gabrielle to transition into an extratropical cyclone. Dissipation is expected in about 4 days.
The cyclone continues to move west-northwest, but a turn toward the north is expected to begin shortly as the remnants of Dorian and an approaching mid-latitude trough provide a weakness for Gabrielle to move toward. The system should accelerate northeastward thereafter. Models remain in good agreement.
FORECAST MAX WINDS
INIT 07/0300Z 45 KT 50 MPH
12H 07/1200Z 50 KT 60 MPH
24H 08/0000Z 55 KT 65 MPH
36H 08/1200Z 60 KT 70 MPH
48H 09/0000Z 60 KT 70 MPH
72H 10/0000Z 50 KT 60 MPH...POST-TROP/EXTRATROP
Atlantic/2018/03L/Archive/7

Tropical Storm Chris Discussion Number 7

Wiki-Hurricanes Forecast Center

5:00 PM EDT Mon Jul 9 2018

Chris has looked a fair bit ragged this morning due to a combination of an influx of dry continental air pooled in the wake of the passing cold front and cooler upwelled waters due to Chris' quasi-stationary motion over the past few days. Dew points in North and South Carolina are around 13C and some of this is making its way into the tropical storm, while a nearby buoy in the southern part of Chris' circulation has been recording locally falling sea surface temperatures to 26C. Numerous decaying convection and outflow boundaries in the southeastern quadrant are indicative of these tepid conditions. Satellite images show a newly developed central area of overcast wrapping around a banding eye, but microwave data from 1457Z show that Chris still has much work to do to rebuild its inner core, with only a partial central band with a large pool of internal subsidence. Nonetheless, convection is expanding and it is fairly clear that the system has resumed intensification. Air Force reconnaissance aicraft running a mission around Chris this afternoon found a decently sized swath of 50kt surface winds and strong flight-level winds, with a peak of 73kt in the southwestern quadrant. Weakest winds are in the northeastern quadrant, at around an estimated 40kt. Using the typical conversion factors from Uhlhorn et. al (2006), the intensity for Chris this advisory has been raised to 60 kt.

Satellite images show Chris is stationary this afternoon, and recon is confirming the still wnadering center of circulation. An upper-level anticyclone is allowing for development of the core of the system without interference by unfavorable winds. Chris is expected to exit its holding pattern tonight as a shortwave trough now over Ontario approaches the system. An accelerated northeasterly heading is expected to commence tomorrow with the trough closer to the system. Tropical Storm Chris sacrificed its larger core this morning to tighten a smaller one in the midst of dry air, but in order to strengthen more appreciably Chris needs to start moving away from its nursery grounds. Environmental sea surface temperatures are near 28C, though they have been depressed two or so degrees. Conditions are rather dry, but with some baroclinic support and warm waters from the periphery of the Gulf Stream, convection is expected to continue and allow for some intensification before cooler northerly waters and extratropically suited conditions return past the Gulf Stream, weakening the system. Towards the end of the

FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 60 KT 70 MPH

12H 10/0600Z 65 KT 75 MPH

24H 10/1800Z 80 KT 90 MPH

36H 11/0600Z 90 KT 100 MPH

48H 11/1800Z 90 KT 100 MPH

72H 12/1800Z 65 KT 75 MPH

96H 13/1800Z 45 KT 50 MPH...EXTRATROPICAL

120H 14/1800Z...ABSORBED BY EXTRATROPICAL CYCLONE
Atlantic/2019/13L/Archive/12

Lorenzo is a behemoth of a hurricane, and it continues to strengthen. The eye, featuring a temperature that has risen above 17C, is nearly encapsulated by a ring of convection cooler than -70C. Satellite intensity estimates have risen to T6.0/115kt from SAB and TAFB, with a higher value of T6.4/124.6kt from UW-CIMSS ADT. Given the increase in organization that continues as of the time of this advisory, the initial intensity is set to 125kt.
Lorenzo is in an exceptionally favorable environment, with broad upper-air lift generated by a passing convectively-coupled kelvin wave, warm ocean temperatures, extremely moist mid-level relative humidity values, and very low wind shear. In the short term, the biggest modulator of Lorenzo's intensity is expected to be inner core changes that cannot be predicted with much skill in advance. Between 24 and 72 hours, the cyclone is likely to interact with an upper-level trough that should inflict moderate levels of shear. Thus, some weakening is expected during that time. On day 4, upper-level winds will again become conducive but Lorenzo is expected to be entering cooler waters. Depending on the timing of this trade-off, some re-intensification may occur around that time. However, weakening is expected to resume by day 5.
The large and powerful hurricane turned northwestward this afternoon, and that trajectory should continue for another 48 hours before Lorenzo curves north and then northeast. Models are very tightly clustered, and confidence is high in the storm's track forecast. Lorenzo is expected to approach the Azores shortly after 5 days from now.
FORECAST MAX WINDS
INIT 26/2100Z 125 KT 145 MPH
12H 27/0600Z 130 KT 150 MPH
24H 27/1800Z 130 KT 150 MPH
36H 28/0600Z 120 KT 140 MPH
48H 28/1800Z 115 KT 130 MPH
72H 29/1800Z 110 KT 125 MPH
96H 30/1800Z 105 KT 120 MPH
Atlantic/2015/02L/Archive/15

## Public advisory

TROPICAL DEPRESSION BILL ADVISORY NUMBER 15

WIKI-HURRICANES FORECAST CENTER

1000PM CDT FRI JUN 19 2015

... BILL STILL A TROPICAL CYCLONE OVER NORTHWESTERN ARKANSAS ...

SUMMARY OF 1000PM CDT...0300 UTC...INFORMATION

LOCATION... 35.7N, 93.6W

ABOUT 100MI... 160KM NW OF LITTLE ROCK, ARKANSAS

MAXIMUM SUSTAINED WINDS...15 KT...30 MPH...50 KM/H

MINIMUM BAROMETRIC PRESSURE... 1005 MB...29.68 INCHES

PRESENT MOVEMENT...ENE AT 9 KT...10MPH...17 KM/H

DISCUSSION AND 48-HOUR OUTLOOK

At 1000 pm CDT, the center of Tropical Depression Bill was located at 35.7N, 93.6W, or about 100 miles (160 kilometers) northwest of Little Rock, Arkansas. Maximum sustained winds were 15 knots (30 mph, 50 km/h), with higher gusts. The minimum barometric pressure was 1005 millibars (hPa; 29.68 inHg), and the system was moving east-northeast at 9 knots (10 mph, 17 km/h). Bill is expected to gradually phase into a remnant area of low pressure as it traverses east-northeastward over the next two days.

NEXT ADVISORY

Next complete advisory at 400 am CDT.

$$

Forecaster TheAustinMan

## Discussion

TROPICAL DEPRESSION BILL DISCUSSION NUMBER 15

WIKI-HURRICANES FORECAST CENTER

1000PM CDT FRI JUN 19 2015

Bill has now moved into northwestern Arkansas. Though the radar appearance of the tropical depression remains ragged and lackluster, ground observations indicate that the circulation remains closed and somewhat well-defined; as a result, Bill will be kept a tropical depression this advisory. Winds remain rather weak at the surface, and as such most of the impacts associated with Bill will continue to be flooding rainfall. Models remain in good agreement that Bill will continue moving east-northeast, gradually accelerating as Bill transitions into a remnant area of low pressure.

INIT 19/0300Z 35.7N 93.6W 15KT 20MPH

12HR 19/1200Z 36.0N 92.1W 15KT 20MPH

24HR 20/0000Z 36.5N 90.5W 15KT 20MPH

36HR 20/1200Z 37.2N 89.1W 15KT 20MPH

48HR 21/0000Z ... MERGED WITH EXTRATROPICAL CYCLONE

$$

Forecaster TheAustinMan
Atlantic/2019/04L/Archive/12

Chantal is now a remnant low. The former tropical cyclone had lacked convection for most of today, stripped bare by 700-500mb relative humidity values on the order of 30-35 percent. This is despite ocean temperatures that have warmed above 26C and upper-level winds that have fallen under 10kt. Given enviornmental parameters, sustained and deep convection is unlikely to return and thus this is Chantal's final advisory. The post-tropical cyclone should move south and then west over the coming days, eventually dissipating between 2 and 3 days from now.
FORECAST MAX WINDS
INIT 24/0300Z 20 KT 25 MPH
12H 24/1200Z 15 KT 20 MPH...POST-TROP/REMNT LOW
24H 25/0000Z 15 KT 20 MPH...POST-TROP/REMNT LOW
36H 25/1200Z 15 KT 20 MPH...POST-TROP/REMNT LOW
48H 26/0000Z 15 KT 20 MPH...POST-TROP/REMNT LOW
Atlantic/2019/09L/Archive/8

Humberto is strengthening at a decent pace this evening. The central pressure has fallen from 1000mb to 989mb since the last advisory, and an Air Force reconnaissance plane has found maximum sustained winds around 60kt. The storm has sported an eye on visible imagery for much of today, only recently obscured by significant convective development as a central dense overcast becomes established. The system is likely to become a hurricane over the next few hours and continue to intensify steadily, if not rapidly, thereafter. Peak intensity is expected in about 72 hours as Humberto interacts favorably with an upper-level trough to its north. By days 4 and 5, this interaction will become an unfavorable one; Humberto should weaken accordingly. In fact, the GFS suggests Humberto may temporarily take on post-tropical cyclone characteristics before regrouping over warmer ocean temperatures. Later forecasts will work out questions regarding this scenario.
The cyclone is moving west of due this north this afternoon. A turn toward the north-northeast is expected overnight or early tomorrow as a mid-level trough pushes southeastward from southeastern Canada into the northwestern Atlantic. This trough should weaken mid-level ridging near Bermuda and shunt it eastward. By days 3 and 4, the southern piece of this trough should cut-off. That evolution, combined with high pressure building in over southeastern Canada in the wake of the trough, provides a unique opportunity for Humberto to temporarily turn north or northwest. This is a solution presented by a non-significant number of GFS and ECMWF ensembles. For now, though, the bulk of model guidance supports a continuation of a northeast track, bringing the hurricane just north of Bermuda between 3 and 4 days from now.
FORECAST MAX WINDS
INIT 15/2100Z 60 KT 70 MPH
12H 16/0600Z 70 KT 80 MPH
24H 16/1800Z 80 KT 90 MPH
36H 17/0600Z 90 KT 105 MPH
48H 17/1800Z 100 KT 115 MPH
72H 18/1800Z 105 KT 120 MPH
96H 19/1800Z 95 KT 110 MPH
Atlantic/2019/01Q/Archive/2

Tropical Depression One-Q Discussion Number 2

Wiki-Hurricanes Forecast Center

12:00 AM AST Sun Mar 24 2019

The depression in the South Atlantic remains fairly disorganized this morning. A recent ScatSat pass revealed that it continues to maintain a well-defined surface circulation. However, associated deep convection had been in the waning phase until recently, and most of it has been centered east of the center. The same ScatSat pass, however, reveals that maximum winds have increased to at least 30kt; that intensity is used for this advisory.

The environment One-Q finds itself in is conducive at the current time. Wind shear is light, with broad anticyclonic flow established around the system, and ocean temperatures are in the neighborhood of 28-29C. This should allow slow organization over the next day or two. Thereafter, upper-level high pressure is expected to shear out and rapidly give way to strong westerly wind shear, which should in turn lead to significant dry air intrusion. Both the ECMWF and GFS intensify One-Q to a moderate tropical storm within 48 hours, with weakening for the remainder of the period. Given data this afternoon, I have increased the forecast peak from 40kt to 45kt, while moving forward the expected time of degeneration. One-Q is still expected to meander for the next 24 hours or so before curving southeast after 48 hours. There is still an outside possibility that the system meanders its way onshore the coastline of South America in the short term as indicated by the UKMET; this is not the preferred solution at this time though.

FORECAST MAX WINDS

INIT 24/0300Z 30 KT 35 MPH

12H 24/1200Z 35 KT 40 MPH

24H 25/0000Z 40 KT 45 MPH

36H 25/1200Z 45 KT 50 MPH

48H 26/0000Z 40 KT 45 MPH

72H 27/0000Z 35 KT 40 MPH

96H 28/0000Z 30 KT 35 MPH...POST-TROP/REMNT LOW

120H 29/0000Z 25 KT 30 MPH...POST-TROP/REMNT LOW
Atlantic/2019/12L/Archive/7

Karen had become significantly better organized this afternoon, and a formative eyewall was evident on radar for a short time. Over the past few hours, though, deep convection has waned and the low-level circulation has once again become separated from its mid-level counterpart. The initial intensity remains 40kt based on recon data. Over the coming days, upper-level winds are forecast to slacken, but mid-level relative humidity values will fall. This trade-off makes for a complicated intensity forecast, with dynamical guidance indicating the potential for a hurricane and some global models foreseeing dissipation. It is still hard to determine which camp is more likely to win out, especially given the rapid changes in structure seen this afternoon. For now, the intensity forecast is largely similar to the previous one.
Karen is now moving north-northeast and will continue in that direction for another day for the next two days. On days 3 through 5, expansive high pressure should build north of the cyclone, forcing Karen to abruptly shift west or west-southwest.
FORECAST MAX WINDS
INIT 24/0300Z 40 KT 45 MPH
12H 24/1200Z 45 KT 50 MPH
24H 25/0000Z 45 KT 50 MPH
36H 25/1200Z 50 KT 60 MPH
48H 26/0000Z 55 KT 65 MPH
72H 27/0000Z 60 KT 70 MPH
96H 28/0000Z 65 KT 75 MPH
Atlantic/2018/04L/Archive/7

Tropical Storm Debby Discussion Number 7

Wiki-Hurricanes Forecast Center

11:00 PM AST Wed Aug 8 2018

Debby is holding on for dear life as it heads for more unfavorable conditions in the far northern Atlantic. Increasing northerly wind shear has allowed the low-level circulation, still well-defined, to become decoupled to the northeast of frazzled convection. Despite apparently the unfavorable upper-level winds, an ASCAT pass at 2315Z showed a renewed region of 40 kt winds, and a plentiful region of gale-force winds southeast of the center of circulation in convection-free region. Given the scope of these winds, Debby's intensity for this advisory has been raised slightly to 40 kt. Still, weakening is anticipated as Debby tracks towards the northeast over excessively cold waters later throughout the course of tonight. It is probable that the afternoon's convection was the last deep convection for Debby as a tropical system, and it is likely that the circulation will remain naked as the system transitions into a remnant low. Absorption into a larger trough and extratropical cyclone could occur sometime Thursday into Friday.

MAXIMUM WINDS FORECAST

INIT 09/0300Z 40 KT 45 MPH

12H 09/1200Z 35 KT 40 MPH

24H 10/0000Z 30 KT 35 MPH...POST-TROP/REMNT LOW

36H 10/1200Z...DISSIPATED
Atlantic/2019/01Q/Archive/16

Tropical Depresssion Iba Discussion Number 16

Wiki-Hurricanes Forecast Center

12:00 PM AST Wed Mar 27 2019

Iba looks nearly the same on the overall as it did this time yesterday with convection limited to a swath southeast of the center, but with unfavorable conditions remaining in place, the low-level center of circulation has become more ill-defined. A 10:39z ASCAT-A pass missed the precise center, but only identified a singular detection of 30 kt winds within convection. Given the deterioration of convection, the scatterometer data, and the loss of organization oberved in the low-level cloud lines, Iba has been downgraded to a tropical depression with winds of 30 kt.

Particularly dry maritime air and outright hostile shear vectors will continue to whittle away at Iba. Sooner or later, Iba is expected to be unable to produce ny sort of organized convection, resulting in an eventual degeneration into a remnant low and later dissipation as conditions remain unfavorable.

FORECAST MAX WINDS

INIT 27/1500Z 30 KT 35 MPH

12H 28/0000Z 30 KT 35 MPH

24H 28/1200Z 30 KT 40 MPH...POST-TROP/REMNT LOW

36H 29/0000Z 25 KT 35 MPH...POST-TROP/REMNT LOW

48H 29/1200Z 25 KT 30 MPH...POST-TROP/REMNT LOW

72H 30/1200Z 20 KT 25 MPH...POST-TROP/REMNT LOW

96H 31/1200Z...DISSIPATED
Atlantic/2019/06L/Archive/1

A tropical depression has formed out of the disturbance that has been lingering off the eastern coast of the United States. Satellite imagery has shown the depression with persistent deep convective banding displaced well to the southeast as a result of westerly wind shear. Upper-level outflow is visible to the north and east but limited toward the west as another result of the shear. An ASCAT-A pass from 1437z indicates a closed circulation with sparse rain-contaminated gales, so the system has been given an initial intensity of 30 kt for the moment.
Six looks to be dealing with very constant conditions over the course of the next few days. Wind shear indices indicate Six is under moderate 15 kt westerly wind shear which is forecast to hold steady from the west turning toward the southwest for the next 60h or so. After this point, shear is forecast to increase with the encroachment of a frontal boundary associated with a closed extratropical cyclone over Canada. Sea surface temperatures are expected to be a warm 28C for roughly the same time period before they begin to drop, falling below 26C in about 3 days. The mid-level environment is somewhat dry, with relative humidity near 50%, although this is forecast to increase to near 60% on day 2. They fall below 50%, but not much further, by around day 4. For the next 60h, Six should be expected to slowly organize in the somewhat favorable conditions. With the encroachment of the front, the storm will enter a more hostile baroclinic environment with high wind shear which should begin to change the nature of the storm as it transitions into an extratropical cyclone on day 3.
Six is currently tracking slowly to the southeast. It is expected to meander generally eastward for the next 24h, then north for the successive 24 in weak mid-level flow before it is picked up by trough. This will accelerate the system toward the northeast and cause the system to lose tropical characteristics sometime on day 3. The post-tropical cyclone will then pass over Atlantic Canada, in particular Nova Scotia potentially as a strong extratropical system, before dissipating by the end of the forecast period as it continues quickly over Newfoundland and is ejected toward the northeast by the trough. Track forecast confidence is fair.
FORECAST MAX WINDS
INIT 26/2100Z 30 KT 35 MPH
12H 27/0600Z 35 KT 40 MPH
24H 27/1800Z 40 KT 45 MPH
36H 28/0600Z 40 KT 45 MPH
48H 28/1800Z 45 KT 50 MPH
72H 29/1800Z 50 KT 60 MPH
96H 30/1800Z 50 KT 60 MPH...POST-TROP/EXTRATROP
Atlantic/2019/10L/Archive/21

Jerry has begun to weaken overnight. The baroclynic forcing that was allowing the storm to retain deep convection off the centre despite the 40+ kt shear has moved away leaving the system with only a tiny amount of deep convection. A aircraft reconnaissance mission currently in the storm has found consistent 45 kt winds, which is the intensity for this advisory. The current weakening trend is not expected to let up, with high shear and considerable dry air impacting the system until it dissipates. The intensity forecast shows steady weakening until degeneration into a remnant low on day 3 and then dissipation by the end of the forecast period.
The track forecast remains similar to the previous advisory, with Jerry currently moving through a weakness in the subtropical ridge. An upper-level trough is expected to take the system towards the east-northeast. Beyond day 3, when the storm is a weakening remnant low, the track forecast gets a fair bit more complicated. Some models, notably the GFS and UKMET, are showing Jerry being left behind by the trough and pushed westwardly underneath a newly expansive ridge. Track confidence remains low on days 3 to 5.

FORECAST MAX WINDS
INIT 24/1500Z 45 KT 50 MPH
12H 25/0000Z 40 KT 45 MPH
24H 25/1200Z 35 KT 40 MPH
36H 26/0000Z 35 KT 40 MPH
48H 26/1200Z 30 KT 35 MPH
72H 27/1200Z 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 28/1200Z 25 KT 30 MPH...POST-TROP/REMNT LOW
Atlantic/2018/03L/Archive/3

Tropical Depression Three Discussion Number 3

Wiki-Hurricanes Forecast Center

11:00 PM EDT Fri Jul 6 2018

Three has not become better organized over the past few hours, and in fact, most associated deep convection has dissipated. This isn't completely surprising given the broad nature of the circulation, with tropical processes still underway. An 01:37z ASCAT pass showed that maximum winds east of the center remained near 25kt, and that is the intensity used for this advisory.

The system is located in a generally favorable environment for intensification. Wind shear is currently low, and although it is expected to increase in about 24 hours as the system interacts with an impinging cold front, this uptick is expected to be transient in nature. Water temperatures are on the order of 28-29°C, more than sufficient for intensification, and warm enough for rapid intensification if Three is able to develop a stable inner core. The surrounding environment is not full of moisture, but it is adequate. Most intensity guidance suggests steady intensification over the next 5 days, including SHIPS at 85kt and LGEM at 70kt. The situation is complicated by the fact that the HMON, ECMWF, and FV3 all show little intensification of the system. Given the favorable environment, the forecast continues to call for a hurricane-strength storm, with some potential caveats.

The system is currently located on the western edge of a subtropical ridge, dictating a north-northwest motion. Steering currents are expected to collapse by this time tomorrow, allowing Three to meander offshore the North Carolina coastline for several days before an approaching upper-level trough accelerates the storm northeast. Most guidance is in good agreement that such a track will occur, with the exception of the HWRF which sent the system into the Outer Banks. This appears to be an outlier for now, but there is still potential for a shift in track that could bring a tropical cyclone close to the East Coast of the United States by the middle of the week.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 25 KT 30 MPH

12H 07/1200Z 25 KT 30 MPH

24H 08/0000Z 30 KT 35 MPH

36H 08/1200Z 35 KT 40 MPH

48H 09/0000Z 45 KT 50 MPH

72H 10/0000Z 55 KT 65 MPH

96H 11/0000Z 65 KT 75 MPH

120H 12/0000Z 70 KT 80 MPH
Atlantic/2019/02L/Archive/5

The satellite presentation of Barry is as messy as ever, with a broad circulation embedded with mesovortices displaced north of an arc of convection across the southern semicircle. Satellite intensity estimates from various agencies argue for a tropical depression, so it is a good thing we have access to reconnaissance data. The latest plane in the cyclone has recorded maximum flight-level winds of 51kt, with peak surface winds around 45kt. Thus, the initial intensity is set to that latter value.
Barry has moved erratically throughout the day, with the two latest fixes forming a due south component. The general motion today has been to the west-southwest, in conjunction with flow around a mid-level ridge across Arizona and New Mexico. There has been little change to the track philosophy for once. The influence of the aforementioned high, as well as a ridge off the Southeast United States coastline, should steer Barry west and then northwest into the central Louisiana coastline on Saturday morning. Model guidance is settling in for a landfall near Marsh Island.
While the track forecast is becoming easier, the intensity forecast sure is not. Barry is a disorganized mess this evening, the result of wind shear and dry air that are more intense than originally advertised in modelling. That being said, since the expectation was initially for a storm that had the potential to undergo rapid intensification on approach to landfall, the change in the forecast here is for a storm that instead only slowly organizes. This will be aided by ocean temperatures near 30C on approach to landfall. Barry still does not have a consolidated low-level circulation, although the radius of maximum winds have become more concentrated about the broad center since this morning. This process should occur slowly over the next 24 to 36 hours, and a slow increase in winds should accompany it. The biggest question for the purpose of this advisory package is whether Barry can achieve hurricane status before landfall. Given that upper-level winds and dry air are likely to persist through landfall, displacing most convection to the south of the center, it is increasingly difficult to imagine a scenario where Barry builds an inner core—a necessary feature to become a hurricane. However, a strictly slow trend upward still argues for Barry to be near the threshold by landfall, and it may be the case that friction from the interaction with land helps boost the storm in its final hours. The peak intensity has been lowered to 60kt, just shy of a Category 1 hurricane, which is now in line with most model guidance. An increasing rate of weakening is expected once inland as the storm moves away from the marshes of Louisiana, and degeneration is now expected in 3 days.
FORECAST MAX WINDS
INIT 12/0300Z 45 KT 50 MPH
12H 12/1200Z 50 KT 60 MPH
24H 13/0000Z 55 KT 65 MPH
36H 13/1200Z 60 KT 70 MPH...AT LANDFALL
48H 14/0000Z 40 KT 45 MPH...INLAND
72H 15/0000Z 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 16/0000Z 20 KT 25 MPH...POST-TROP/REMNT LOW
Atlantic/2018/02L/Archive/10

Post-Tropical Cyclone Beryl Discussion Number 10

Wiki-Hurricanes Forecast Center

5:00 PM AST Sun Jul 8 2018

Beryl is no longer a tropical cyclone. A reconnaissance aircraft found that, while maximum winds remain near 45 mph to the north of the lowest pressures, a well-defined and closed low-level circulation does not exist. As such, Beryl is being declared an open trough at this time. Convection continues to burst intermittently as the system moves west-northwest, and localized heavy rainfall will be a threat to the Leeward Islands in addition to tropical storm-force winds. The remnants of Beryl should cross Hispaniola late Monday into Tuesday, emerging into the southwestern Atlantic thereafter. Several global models suggest the possibility of regeneration when environmental conditions become more favorable, and this is being given a medium chance, 40%, for now.

FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 40 KT 45 MPH...REMNANTS

12H 09/0600Z...DISSIPATED
Atlantic/2019/06L/Archive/8

Erin is a disjointed mess this morning. The low-level circulation, albeit well-defined, is accelerating north, far removed from associated convective activity that has diminished in recent hours. Satellite intensity estimates have fallen this morning, but I would rather wait for ASCAT before downgrading the system. Still, despite warm waters and some expectation for lower wind shear today, intensification does not seem all that likely. Extratropical transition is expected in about 36 hours, with dissipation by day 3 as the post-tropical low is absorbed by a larger extratropical cyclone.
As mentioned above, Erin is accelerating northward today. The northward motion should become more north-northeast or northeast by tomorrow as an approaching upper-level trough erodes the Bermuda high to the cyclone's east. This should send the cyclone toward Nova Scotia and Newfoundland.
FORECAST MAX WINDS
INIT 28/1500Z 35 KT 40 MPH
12H 29/0000Z 35 KT 40 MPH
24H 29/1200Z 30 KT 35 MPH
36H 30/0000Z 30 KT 35 MPH...POST-TROP/EXTRATROP
48H 30/1200Z 30 KT 35 MPH...POST-TROP/EXTRATROP
Atlantic/2019/08L/Archive/15

Gabrielle remains an exposed tropical cyclone this afternoon, although not in the common sense through most of the storm's life. High clouds wrap around the low-level circulation, with more vigorous thunderstorm activity to the south and west. An earlier ASCAT pass showed sporadic patches of 40-45kt winds within that convection, so the initial intensity remains 45kt.
Ocean temperatures have risen to 28C and mid-level relative humidity values are in the process of climbing over 40 percent. However, upper-level winds have not yet fallen, and there has been a significant change today in predicted values moving forward. Whether it be from Gabrielle's significant center reformation this afternoon, or maybe the quicker forward motion than originally anticipated, the 200mb pattern now looks to remain generally medicore over the coming days. This has resulted in a downtrend in intensity guidance, with newest runs focused around strong tropical storm or minimal hurricane strength. While for continuity purposes I have not lowered our forecast that dramatically, I have reduced expected values. The timing of degeneration and dissipation remains the same.
Gabrielle is racing west-northwest today as high pressure over the Azores builds. However, the approach of a mid-latitude trough and the extratropical rendition of Dorian should send Gabrielle toward the north and then northeast at an even faster rate over the coming days. Models remain in good agreement regarding this solution.
FORECAST MAX WINDS
INIT 07/1500Z 45 KT 50 MPH
12H 07/0000Z 45 KT 50 MPH
24H 08/1200Z 50 KT 60 MPH
36H 08/0000Z 55 KT 65 MPH
48H 09/1200Z 65 KT 75 MPH
72H 10/1200Z 75 KT 85 MPH
96H 11/1200Z 55 KT 65 MPH...POST-TROP/EXTRATROP
Atlantic/2019/03L/Archive/1

The area of disturbed weather in the Bahamas has somewhat unexpectedly organized into a tropical depression this afternoon. Visible satellite imagery over the course of the past few days indicated a very sharp wave axis, but it did not depict a well-defined circulation or organized convective activity. That has changed today, with a wide swath of shower and thunderstorm activity that has become more centrally focused since noon. Two ASCAT passes from around that time indicated a closed and organized surface low. One pass actually registered tropical storm-force winds east of Andros Islands, but it is likely these values were influenced by shoaling and not representative of the cyclone's strength. Therefore, without completely discounting the possibility that a tropical storm has formed, the initial intensity is set to 30kt.
The storm system has been interacting with an excessively strong convectively-suppressed kelvin wave over the past few days, and it is embedded within a region of high environmental pressures. These two factors were initially expected to curtail development. What appears to have happened is that the system was able to maintain its vigor until reaching the western Bahamas, where the effects of the kelvin wave have subsided -- and in fact have been replaced by a favorable, convectively-coupled wave -- and abnormally high ocean temperatures around 31C have provided sufficient instability for convective formation. Thus, with wind shear expected to be light for an additional 36 hours, and the storm's track expected to remain east of Florida, the stage appears set for maintenance, if not some slight development in the short term, and it is not out of the question that Three becomes a tropical storm, Chantal, tomorrow. After 36 hours, the environment will become increasingly hostile as a front impinges on the cyclone, and dissipation is expected about 48 hours from now.
Three is being steered on the southwest periphery of a broad mid-level ridge across the central Atlantic. As the storm rounds the edge of this ridge, and moves toward a weakness between the ridge over the Atlantic and one over New Mexico, it should curve northwest then north and finally northeast. There is some model discrepancy regarding the sharpness of this recurve, with models such as the GFS bringing the remnants of the cyclone ashore in North Carolina. This appears to be a western outlier right now, with the most likely solution being that Three remains offshore the East Coast.
FORECAST MAX WINDS
INIT 22/2100Z 30 KT 35 MPH
12H 23/0600Z 30 KT 35 MPH
24H 23/1800Z 30 KT 35 MPH
36H 24/0600Z 30 KT 35 MPH
Atlantic/2019/05L/Archive/22

Dorian's intensification has slowed but is still ongoing. Satellite presentation for the past few hours has remained much the same, although the central dense overcast has been expanding slightly. Deep convection intermittently colder than -80C has been firing on the south side of the center and no eye is evident yet on infrared satellite imagery. It is possible that the hurricane has intensified a bit since the last advisory, but it has not made it very clear, so the initial intensity remains 90 kt for now.
While Dorian has consolidated an inner core, there is still some wind shear that the hurricane has to deal with. Wind shear currenly sits at about 10 kt from the southeast as a result of the upper-level setup with a cyclone to the west of the hurricane and an anticyclone to the southeast inducing a southeasterly flow over the top of the cyclone. This is creating the current elongated appearance and is allowing some dry air to sustain the dry slot. That is not to say that conditions aren't favorable, though, steady intensification is likely. It is to say that conditions will become even more favorable tomorrow as wind shear really becomes a non-issue. Sea surface temperatures are hovering near 29C for the remainder of the forecast period and mid-level relative humidity values will be supportive as they currently stand near 60%, with the potential to increase a bit over the next few days. This will allow Dorian to become a category 4 and it will likely make landfall in Florida at that intensity on day 5.
Dorian continues to move northwest this morning. This track should continue for much of the day today before the storm begins to turn toward the west as a result of a mid-level ridge developing over the Southeast US. By midday tomorrow Dorian should be tracking near due west as a result of the ridging until it makes landfall in Florida early on day 5. A passing shortwave trough through the Great Lakes and Midwest region will be the deciding factor in how much the ridge gets eroded, resulting in Dorian slowing by the end of the forecast period and potentially recurving if the trough is strong enough.
FORECAST MAX WINDS
INIT 30/0900Z 90 KT 105 MPH
12H 30/1800Z 95 KT 110 MPH
24H 31/0600Z 105 KT 120 MPH
36H 31/1800Z 115 KT 130 MPH
48H 01/0600Z 120 KT 140 MPH
72H 02/0600Z 125 KT 145 MPH
96H 03/0600Z 125 KT 145 MPH
Atlantic/2019/04L/Archive/9

Chantal continues to crawl across the northern Atlantic this evening, featuring the same convective characteristics it has for the past day. Intermittent bursts of deep convection continue to fire east of the center, only to be whisked away by upper-level winds that are not yet conducive. A 23z ASCAT pass showed maximum winds of 30kt to the southeast of the center, and thus that remains the initial intensity for this advisory. While wind shear should lessen overnight, and the cyclone is moving over ocean temperatures near 26C, extremely dry mid-level air should prevent intensification and instead cause degeneration to a remnant low about 36 hours from now. Dissipation has been brought forward to day 3.
A mid-level ridge is gaining strength over the subtropical Atlantic. This ridge has caused Chantal to curve toward the southeast. A turn toward the west and then north is expected over the coming days, with the system remaining well west of the Azores as that occurs.
FORECAST MAX WINDS
INIT 23/0300Z 30 KT 35 MPH
12H 23/1200Z 30 KT 35 MPH
24H 24/0000Z 30 KT 35 MPH
36H 24/1200Z 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 25/0000Z 25 KT 30 MPH...POST-TROP/REMNT LOW
Atlantic/2019/05L/Archive/49

Dorian remains a symmetric hurricane on satellite, but it continues to weaken this evening, and there are increasingly signs that the system is in the initial stages of extratropical transition. A convergence zone/faux triple point is taking shape in the northeastern quadrant, and the storm's convection is becoming increasingly weighted to the northern semicircle. The NOAA plane investigating Dorian found peak flight-level winds of 88kt and peak SFMR winds of 83kt. These numbers support lowering Dorian to 85kt for this advisory.
Dorian will continue to weaken as upper-level winds increase, dry air entrainment becomes more prevalent, and the hurricane continues to interact with non-tropical features. Extratropical transition is expected in about 48 hours. Interestingly, global models have latched onto the idea of significant strengthening while this transition occurs, most notably the ECMWF which has a sub-950mb cyclone impacting Nova Scotia. While pressure falls seem feasible, it seems more likely that maximum winds will steadily decrease as the circulation size grows. The extratropical rendition of Dorian should be absorbed by an even larger non-tropical low on day 5.
Dorian is moving northeastward and will continue to move in that general direction over the next five days, save for a temporarily north-northeast deviation around 72 to 96 hours. On this track, Dorian should cross the Outer Banks of North Carolina tonight, Nova Scotia on Saturday afternoon, and Newfoundland on Sunday morning.
FORECAST MAX WINDS
INIT 06/0300Z 85 KT 100 MPH
12H 06/1200Z 80 KT 90 MPH
24H 07/0000Z 75 KT 85 MPH
36H 07/1200Z 70 KT 80 MPH
48H 08/0000Z 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 09/0000Z 55 KT 65 MPH...POST-TROP/EXTRATROP
96H 10/0000Z 40 KT 45 MPH...POST-TROP/EXTRATROP
Atlantic/2019/05L/Archive/23

Dorian has cleared an eye. Visible and infrared channels show a dramatic warming of the center temperature over the past hours. Air Force reconnaissance planes investigating the hurricane have found a central pressure down to 972mb. Maximum flight-level winds were around 100kt, with SFMR values between 90-95kt. Therefore, the initial intensity is set to 95kt for this advisory. Dorian is expected to become a major hurricane later today and further intensify to a Category 4 hurricane by the end of the weekend as it remains in an exceptionally favorable upper-level environment, surrounded by an increasingly moist airmass, over ocean temperatures in excess of 28C. Weakening is expected as Dorian curves up eastern Florida.
The hurricane continues to move northwest. A turn toward the west is expected by tomorrow morning as high pressure builds offshore the Southeast United States. This westward turn may be accompanied by a south of west deviation at some point on Sunday or Monday, but regardless, Dorian is still expected to strike the eastern shoreline of Florida on Tuesday as an exceptionally powerful hurricane. It is becoming increasingly likely that Dorian will curve northward after landfall while slowing down.
FORECAST MAX WINDS
INIT 30/1500Z 95 KT 110 MPH
12H 30/0000Z 100 KT 115 MPH
24H 31/1200Z 105 KT 120 MPH
36H 31/0000Z 115 KT 130 MPH
48H 01/1200Z 120 KT 140 MPH
72H 02/1200Z 125 KT 145 MPH
96H 03/1200Z 115 KT 130 MPH...INLAND
Atlantic/2019/05L/Archive/7

Dorian has continued to improve since the last advisory, with more expansive central convection. A series of microwave passes this morning showed that the system continues to harbor a low-level inner core, though attempts at a substantive eyewall continue to be disrupted by mid-level dry air entrainment. Satellite intensity estimates are oscillating between T3.0/45kt and T3.5/55kt, so the initial intensity remains unchanged for this advisory.
Dorian has turned toward the west-northwest, and a west-northwest to northwest trajectory is expected for the next 4 days as the mid-level ridge that is positioned northeast of the Caribbean weakens. On its current path, Dorian should pass near or over Dominica and continue through the central Leeward Islands tomorrow morning, arriving in the Dominican Republic early Thursday. Model guidance has shifted further east since last night, and it is becoming increasingly likely that Dorian simply scrapes the northeastern coastline of Hispaniola rather than tracking through the center of the island. This has significant implications for the intensity forecast, as it means Dorian may maintain hurricane strength longer than anticipated and increase the threat to the Turks and Caicos Islands, as well as the Bahamas. The possibility that Dorian still dissipates over land is not zero, however. By day 5, a building ridge off the Southeast United States may force the cyclone back toward the west-northwest or west.
Dorian has met expectations so far, with generally gradual bouts of intensification interrupted by dry air entrainment. The environment is undergoing changes now, with a decrease in upper-level winds, an increase in relative humidity, and a rise in ocean temperatures. These changes should allow Dorian to achieve hurricane strength within the next 24 to 36 hours, provided its small size does not make it especially susceptible to outside influences. Global models continue to show little interest in Dorian, but it is worth pointing out that the cyclone is stronger than those models suggested it would ever be. The SHIPS and LGEM continue to point toward a high-end Category 1 or even a Category 2 hurricane prior to landfall in the Dominican Republic. On the other hand, the HWRF is back to its previous solutions of weakening in the eastern Caribbean, with intensification delayed until after the storm exits the region. It is hard to say which model solution is correct here, but I see little reason to deviate from previous forecasts at this point. The next big question by the end of the period is whether Dorian gains significant strength over the southwestern Atlantic. This will depend on the degree of land interaction, and so only slight development is represented here.
FORECAST MAX WINDS
INIT 26/1500Z 55 KT 65 MPH
12H 26/0000Z 60 KT 70 MPH
24H 27/1200Z 65 KT 75 MPH...MOVING THROUGH WINDWARD ISLANDS
36H 27/0000Z 70 KT 80 MPH
48H 28/1200Z 75 KT 85 MPH
72H 29/1200Z 70 KT 80 MPH...INLAND
96H 30/1200Z 40 KT 45 MPH...OVER WATER
Atlantic/2018/03L/Archive/1

Tropical Depression Three Discussion Number 1

Wiki-Hurricanes Forecast Center

11:00 AM AST Fri Jul 5 2018

A non-tropical low centered between Bermuda and Savannah, Georgia has been producing organized convection since the overnight hours. Visible images from yesterday evening confirmed a closed low-level circulation which has expanded on the basis of a 20kt west-northwesterly wind observed by a ship south of the suspected center of the area of low pressure. High resolution rapid scan is confirming this center is shrouded by convection this morning with microwave seeing definite circulation and internal banding at the mid-levels. TAFB estimated T1.5/25kt at 1200Z, but since the system has improved in coverage of the center I have set the intensity to 30 kt for this first advisory on the newly formed Tropical Depression Three.

The steering forecast for Three is complicatedf to say the least. Three is currently moving northwest around a subtropical ridge in the general direction of the Outer Banks, with a shortwave trough over Quebec providing some northerly ascent. However, global guidance suggests that the frontal boundary associated with this trough takes a rather shallow angle on the developing system, forcing it to stall or back southward as opposed to the ordinary action of kicking it out towards the northeast. Building heights behind the passing front could impart some westerly motion on Three as it stalls for a few days, waiting for another trough around the day 5 time period to kick the system out northeast. The current forecast track is close to the mean of statistical guidance and follows this stall, westward drift and eventual northeast trajectory, though the northeastern push will mostly take place towards the end of the forecast window and after the forecast window.

The upper-air environment for Three is rather conducive for development, with cold -55C upper-air temperatures and warm Gulf Stream waters in excess of 28.6C throughout the forecast period, owing to anomolously warm subtropical waters off the East Coast this year some 2-3C above normal. Before the cold front clears past the developing tropical depression, the system is expected to remain rather dormant. Afterwards, intensification should commence fairly steadily through the end of the forecast window.

FORECAST POSITIONS AND MAX WINDS

INIT 06/1500Z 30 KT 35 MPH

12H 07/0000Z 30 KT 35 MPH

24H 07/1200Z 30 KT 35 MPH

36H 08/0000Z 30 KT 35 MPH

48H 08/1200Z 35 KT 40 MPH

72H 09/1200Z 40 KT 45 MPH

96H 10/1200Z 45 KT 50 MPH

120H 11/1200Z 60 KT 70 MPH