Aikyam-Lab/Synoptic-Bench huggingface dataset:
As of this afternoon, upper level ridging is present over the Plains with a deep trough downstream over the East Coast and an upper low just off the West Coast. This upper low will slowly weaken as it approaches the area tomorrow. While overall moisture and forcing for ascent will be low, weak frontogenesis may still lead to a few showers in the afternoon and evening, especially along and south of I-35 closer to the track of the decaying upper low.
Forecast for tonight remains on track as a broad H5 trough pivots through the eastern U. Winds will become light and variable by the early morning hours as the high continues to build in. MA Chattanooga Airport, TN 60 41 54 42 57 / 0 10 50 20 10 Knoxville McGhee Tyson Airport, TN 56 38 53 38 55 / 0 10 50 20 10 Oak Ridge, TN 55 38 53 38 55 / 0 10 50 20 10 Tri Cities Airport, TN 50 34 51 35 52 / 0 10 30 20 0.
An upper level short wave trough, currently seen on satellite over Nevada, will make its way towards the Panhandles by late Thursday afternoon and will likely bring some light or moderate rain to KGUY and KDHT between 23Z and 02Z. Depending on the track of the short wave trough, we will have to monitor to see if the storm system digs a bit further south. BY the late afternoon, the next upper level low will be approaching from the northwest, which may bring a few showers to KGUY and KDHT before the end of the TAF period. The higher chances for showers will occur after 00Z on Thursday, yet even those may be few and far between.
A modest short wave trough axis will be exiting eastern Kentucky Friday night, with deep enough moisture lingering in the low levels to support at least a slight chance of precipitation through the evening.
958 PM CST Wed Dec 4 2019 Temperatures were once again trending a bit lower than forecast due to a fairly steady drop this evening with broad high pressure, calm winds and only thin high clouds. Adjusted many areas down 1 to 3 degrees for the lows, but once again the overnight drop should only be a few more degrees as temperatures approach the dewpoints and the high clouds increase slowly and thicken at times. The associated cold front is currently forecasted to pass through the area on Friday. Once the cold front passes, it stalls over the gulf.
Sea fog lingering over the Lower TX coast could creep back up into Matagorda Bay overnight. Based on these trends, we could see a little more fog coverage tomorrow night ahead of the next cold front.
Temperatures into the 40s across the interior, Gulf coast and western east coast suburbs will be in the low 50s with a few sites maybe dipping into the upper 40s. Today looks to be the last cooler day as high pressure over northern Gulf states will begin to slowly slide eastward towards the SE CONUS, veering winds from northerly to northeasterly. Highs across the area today will be in the low to mid 70s. With the wind getting a little more of an easterly component overnight lows tonight will be a few degrees warmer particularly for east coast.
1017 PM MST Wed Dec 4 2019 Current upper air analysis shows trough centered off the central California coast with weak ridging and subsequent northwest flow across the northern US. A weak cold front will push through the region late day Thursday and bring with it a moist, cold airmass. Low levels should saturate during the late afternoon and post-frontal low stratus and fog/freezing fog will develop across portions of the forecast area into Friday morning.
At the surface, a weak cold front will approach from the west, most likely cross the region early Friday.
244 AM CST Thu Dec 5 2019 High pressure remains over the Mid-South this morning. The high will shift east today. Abundant cirrus clouds are already streaming into the area ahead of a developing low pressure system located over the Texas Panhandle. A warm front will lift across the area late this afternoon which may allow a few showers to develop across portions of Northeast Arkansas. Winds will turn around to the north on the backside of the low which will keep lingering drizzle across the area during the afternoon hours on Friday.
An area of high pressure is slowly working into the area tonight leading to a slackening of the winds at the surface from southwest to northeast and this could lead to some valley fog late. The winds will generally remain light under the high pressure at around 5 knots.
As of this afternoon, upper level ridging is present over the Plains with a deep trough downstream over the East Coast and an upper low just off the West Coast. This upper low will slowly weaken as it approaches the area tomorrow. While overall moisture and forcing for ascent will be low, weak frontogenesis may still lead to a few showers in the afternoon and evening, especially along and south of I-35 closer to the track of the decaying upper low. Quiet weather looks to settle into the region over the weekend as midlevel ridging overspreads the Plains.
Even with no precip, temps could be a degree or so cooler than guidance blends indicate for max temps.
251 AM CST Thu Dec 5 2019 Weak low pressure is moving across North Dakota early this morning. As high pressure drops in from northwest to southeast, winds will become calm Thursday night across the Missouri River valley. Return flow will set up on Friday with breezy southerly winds drawing up warmer temperatures into central SD again.
300 AM CST Thu Dec 5 2019 The combination of clear skies and calm winds with the high pressure system over the Quad State region is resulting in chilly conditions overnight with much of Southern Illinois below freezing. Lows Thursday night will be warmer with temperatures in the low 40s. Behind this system more northerly flow will bring cooler air.
Mostly sunny skies for much of the day coupled with southerly winds will allow afternoon max temps to reach into the low to mid 50s across southern Indiana and central Kentucky and close to 60 across south central Kentucky. Increasing mid and high clouds will occur this evening ahead of an approaching cold front, while light rain chances will enter into our western counties by early Friday morning and continue to spread eastward across the entire CWA by late morning. Southerly flow and cloud cover will keep Friday morning temps in the low 40s with highs expected in the upper 40s in the north and increasing toward the low to mid 50s in our south.
1110 PM CST Wed Dec 4 2019 High pressure centered over southern NOAM extends north into the central-northern Plains this afternoon, with virtually no clouds over MN/WI down through the mid-Mississippi River Valley. High pressure will be suppressed to the southeast through tonight as a weak area of low pressure approaches from the Dakotas. As the system departs to the east Thursday night, cold air advection will kick in as colder western Canadian high pressure settles atop the area by daybreak Friday morning. Friday will be the coldest day of the week with cold high pressure settling over MN/WI. Even with plenty of sunshine, cold air advection will win out, keeping highs in the upper teens to the lower 20s.
Latest surface analysis places a double barrel low pressure system over Texas. The low pressure system is expected to lift NNE through the ArkLaTex region over the next several hours. An attendant warm front is expected to lift across Mississippi and reach the TN and MS border late tonight. Simultaneously, the upper low currently over south Texas will lift northeast and take on a negative tilt over Arkansas. Then, a warm front is progged to lift north and place most of north Mississippi in the warm sector of the cyclone. If storms can form along the warm front, a brief spinup tornado will be possible along with the threat of damaging wind gusts. Storms that form north of the warm front will have the potential for small hail and damaging winds.
552 PM MST Thu Dec 31 2020 Mid and high based clouds are moving from west to east across southeast Wyoming and the western Nebraska Panhandle this evening ahead of an upper level trough axis. The trough axis will pass through New Years morning, followed by clearing skies and dry conditions under a light wind regime. The northern stream flow was more tame, with a couple of progressive weak short wave troughs. A weak frontal passage will bring slightly cooler temperatures tonight and Friday.
As the upper level low tracks towards the area Friday, we'll move into a region of upper level divergence Friday morning and the jet will set up southeast of us through the day.
Precipitation is not expected on Friday as a high pressure to our northeast keeps dry air over the area in a south flow. Highs on Fri will be reaching the lower to mid 80s for a warm start of the new year.
Weak isentropic lift was responsible for light snow over the north-central, north of the warm front placed just north of Highway 200 in central North Dakota. Ridge aloft begins to build Friday with surface winds turning southwesterly.
Early this afternoon, high pressure was located across the Great Lakes as clouds remained across the area. Freezing rain will be confined to the far south and east, elsewhere snow is expected. This system will bring warmer temps to the southern CWA and then to the far east as it moves through the area. The NBM continues to be warmer for this system as well suggesting more of freezing rain than is expected. With the overall upper level low filling, I doubt the strong advection that some of the guidance as. There is a low threat for freezing rain accums reaching near 0.
522 PM PST Thu Dec 31 2020 A cold frontal passage this morning brought some light showers across Central California.
This won't stop a WSW wind from prevailing throughout the weekend and at least bringing us to around freezing.
529 PM PST Thu Dec 31 2020 Updated air quality section A cold frontal passage this morning brought some light showers across Central California.
601 PM CST Thu Dec 31 2020 Surface analysis this afternoon shows extensive high pressure centered over IL/IN, expanding westward into the mid-upper Mississippi River Valley. Weak PVA well in advance of the warm front has been just enough to keep the low stratus in place. With little impetus to kick the shallow moisture out of the region, the low stratus is expected to advect back to the west and encompass much of the area once again on Friday. The upper level flow will remain split between the fairly inactive northern stream and more noticeably active southern stream, as evidenced by the potent storm system coming out of the Deep South and into the northeast over the next couple days and low pressure centers remaining north in Canada.
752 PM EST Thu Dec 31 2020 Low pressure will return widespread precipitation tomorrow. Mid morning subfreezing temperatures will support the potential for freezing rain too. A quiet night is expected to continue under lingering high pressure. Subfreezing morning sfc temperature are likely to create a brief period of hazardous weather, in the form of freezing rain, as a low pressure advances from the southeast. Ice accumulations may be a trace to a tenth of an inch across the region, higher amounts in the eastern ridges if low level winds take full advantage of direct upsloping. Persistent warm advection should gradually increase sfc temperature above freezing from south to north, with a changeover to rain expected, thus ending the freezing rain threat.
The freezing line continues to gradually work its way north. As such, the freezing line should be north of the CWA completely around 12z, so we may be able to cancel the Advisory a few hours early. Temperatures will fall into the low to mid 30s overnight as the trailing surface cold sweeps through the CWA. Late tonight, a weak trailing trof feature will settle across the southern Pennyrile. We have a chance of some light rain Saturday night as an upper level low moves across the area.
As the strong system over the lower Mississippi Valley moves north- northeast the next 12-24 hours, the increasing boundary layer jet will pull warmer temperatures back into the region with isentropic lift. This is well covered with the High Wind Warning and Advisory. For Friday, models show a warm front moving north across Alabama and Georgia but remaining south of the area.
An area of freezing rain and rain will shift in from the south late this morning into the afternoon. Roads will likely become very slippery for a time until temperatures warm above freezing and precipitation changes to mostly rain.
A deep upper low near Del Rio, TX is about to eject in negative tilt fashion to the north-northeast across the southern plains and into eastern Kansas by Friday afternoon. No precipitation is expected with this system since the low to mid level moisture will have been shunted to the east with the first system.
High pressure will build across the region to start the New Year.
259 AM EST Fri Jan 1 2021 The Florida peninsula is wedged between a strong area of high pressure over the western Atlantic and a strong low pressure system over the southern Plains. The low pressure system will lift rapidly northeast across the mid Missouri valley today. An associated cold front will push slowly across the western Florida panhandle today, but will become parallel to the U/L flow tonight and stall over that region with high pressure holding across the Florida peninsula with continued above normal temperatures under variably cloudy skies.
Aloft, mid-level high pressure has built in over the area while the mid-level impulse driving the frontal boundary and its parent low will lift northeastward, keeping the front from advancing into peninsular Florida to end the week and kick off the weekend. With the high pressure holding influence of the region's sensible weather, additional insolation should allow temperatures to continue their upward trend with most of the area reaching the 80s the next couple of afternoons. Some of the morning could also be warm with 70s along the Atlantic coast thanks to the persistent southeasterly to southerly flow which could threaten some of the high min temp records.
The upper trough which brought precipitation to the area has shifted to the east with high pressure building in its wake.
1031 PM MST Thu Dec 31 2020 The synoptic overview includes a highly amplified ridge aloft over the western CONUS and two closed upper level lows, one over the desert southwest and another over the southern plains. The desert southwest closed low will propagate from southern Nevada towards southern New Mexico, which will bring isolated snow showers over the Continental Divide first, later this evening, and secondly tomorrow afternoon. Mid-level clouds are expected to form, which will keep temperatures warmer than what they have been the last two nights. If those clouds fail to form, the low temperature forecast for the mountain valley will be too warm. A weak cold front passes over the region late this evening and into the overnight, which will bring gusty (up to 25 kts) winds over the plains and slightly cooler temperatures over the plains.
` There are currently two cut off troughs across the southern US with one over Texas and another over Arizona. For those going out and about during this New Year's Eve night, the weather won't be much of an issue with temperatures in the low 30s to upper 20s across the urban corridor with light winds. These winds won't be strong but will bring in slightly cooler air tomorrow as highs will be roughly 5 degrees colder. Friday night, a large upper level low pressure system will be over the Southern Plains States with a dry northerly flow aloft over Colorado. On Saturday, there will be some ridging over the state which will bring warmer temperatures and continued dry weather to North Central and Northeastern Colorado.
259 AM CST Fri Jan 1 2021 First and foremost, from all of us at NWS Sioux Falls, we wish you a happy new year! We're starting 2021 off with a continuous stream of upper cirrus thanks to a large upper low spinning across the Ozarks. Today: A quiet day is anticipated for the region, as a stretched out low-mid level trough drops southeast. The combination of light winds, already present stratus, and low-lvl ridging should lead to higher confidence in fog development (some dense) into Saturday morning.
Track of the low will take bulk of the precipitation south and east of our area with perhaps a dusting to 1/2 inch expected across portions of northeast IA into far southwest WI. High pressure drifts across the region Saturday into Saturday night for a quiet period but stratus and patchy fog looks to persist with weak airflow and moisture trapped under the inversion.
A weak low pressure system will deliver a few snow showers to portions of northern Arizona overnight into Friday. Over the weekend, high pressure will bring a return of dry weather and warmer temperatures.
As the low moves northeast overnight, temperatures will continue to climb.
The other issue is the extent of the low clouds that were in the Minot area and satellite showed were advancing and expanding south and east. Weak isentropic lift was responsible for light snow over the north-central, north of the warm front placed just north of Highway 200 in central North Dakota. Ridge aloft begins to build Friday with surface winds turning southwesterly.
1015 PM CST Thu Dec 31 2020 Latest observations across the region show mostly sunny skies, south to southeasterly winds, and temperatures in the low to mid 20s. Heading into the evening, expect a ridge of high pressure to gradually move overhead, allowing light and variable winds to prevail overnight.
with a trough in New England and another in the western U. The low in northern Mexico heads northeast into the mid Mississippi Valley by 00z Sat. Lows tonight could be tricky as well as clouds have been decreasing and the lows could occur around midnight with the lowest wind speeds then before they pick up and it is conceivable that the temperatures could rise after midnight as the wind begins to increase. For the weekend, low pressure is progged to track from the eastern Great Lakes quickly into New England Saturday.
A ridge of high pressure to the east and a deepening low pressure system in the western Gulf waters will keep breezy southerly winds around 15 to 20 kts in place over the coastal waters tonight with swells keeping offshore waves around 5 to 7 feet. The low pressure system will move eastward along the northern Gulf coast on Friday, stalling in the northeastern Gulf waters around Friday night.
Model soundings are once again hinting at the low stratus deck expanding overnight tonight, leading to yet another cloudy night.
A significant weather system to affect the forecast area today as low pressure over the Arklatex with warm front across the southeast approaches the eastern Tennessee Valley with increasing rain showers and strong winds loft causing strong southeast winds over the eastern mountains and foothills early this morning and through the day.
High pressure will bring lighter winds and warmer days Friday and Saturday.
1050 PM CST Thu Dec 31 2020 Surface analysis this afternoon shows extensive high pressure centered over IL/IN, expanding westward into the mid-upper Mississippi River Valley. Weak PVA well in advance of the warm front has been just enough to keep the low stratus in place. With little impetus to kick the shallow moisture out of the region, the low stratus is expected to advect back to the west and encompass much of the area once again on Friday. The upper level flow will remain split between the fairly inactive northern stream and more noticeably active southern stream, as evidenced by the potent storm system coming out of the Deep South and into the northeast over the next couple days and low pressure centers remaining north in Canada.
The synoptic pattern across the CONUS at 21Z today is featuring a northern stream of energy across the northern tier of the CONUS with a very pronounced upper low and trough with the closed center circulating and translating into southwestern TX. The upper system from TX appears to be highly dynamic with a compact upper low deepening at the current hour. Timing of the low should allow for impacts to last through the morning into early afternoon, so have kept the Advisory/Winter Storm Warning combo in effect through the afternoon on Friday.
1037 PM MST Thu Dec 31 2020 Mid and high based clouds are moving from west to east across southeast Wyoming and the western Nebraska Panhandle this evening ahead of an upper level trough axis. The trough axis will pass through New Years morning, followed by clearing skies and dry conditions under a light wind regime. The northern stream flow was more tame, with a couple of progressive weak short wave troughs. A weak frontal passage will bring slightly cooler temperatures tonight and Friday.
Dropped some of the low temperatures where staying clear longer. The low level winds are somewhat elevated this evening, however overnight drop off.
259 AM CST Fri Jan 1 2021 Main challenge/concern is changeover from liquid/freezing to frozen precip this morning across the headline areas. Latest short term models support mainly rain/freezing rain with light to moderate ice accums for areas southeast of the turnpike through 12z. However, as the upper low spins northeastward across eastern Oklahoma later this morning, dynamic cooling aloft is expected to support a changeover to snow. The upper low now over northern Mexico is still progged to lift northeastward across the southern Plains tonight before moving into the Ozarks on Saturday.
The most significant change is to add Ottawa County to the winter weather advisory, as temperatures are right at the freezing mark in that area, so some minor ice accumulation is possible on elevated surfaces. The rest of the forecast is trending well, with the freezing line generally along or just north of Interstate 44. As the Texas upper low moves towards and eventually into eastern Oklahoma, temperatures aloft will cool, allowing for a changeover to sleet and snow in parts of northeast Oklahoma.
More substantive features evident on CONUS WV imagery include a robust cyclone taking shape across the srn Plains/Lower MS Valley and another upper low digging thru the desert SW. Farther west, an upper ridge axis is shifting from the ern Pacific toward the West Coast. Aforementioned upper ridge will flatten as it shifts ewd toward the Rockies/Plains thru the end of the week. However, given that none of these disturbances are associated with substantial deep moisture or appreciably cooler air, main impact of each will be a period of breezy conditions. In particular, pressure gradient tightens considerably across portions of southern Campbell County during both Friday night and Saturday night as trofs approach, which could lead to some gusts in excess of 40 kt both nights into the following mornings.
The upper low that we are tracking this evening has ejected out of Mexico and is now about 50 miles north of San Antonio, TX. This is a favorable track for our snow chances in the eastern Texas Panhandle, but also increases the pressure gradient potential in the southeast Texas Panhandle as the low will track a little closer than previously thought. An upper low to our southeast is expected to move into Oklahoma this evening.
1024 PM MST Thu Dec 31 2020 Some light snow shows linger this morning across the west and the south as the last bit of energy from the weak trough moves across the area. Temperatures will break the freezing mark for many locations east of the Divide this afternoon with low-elevations west of the Divide reaching the upper 20s to near 30. Otherwise, most of the region will see a dry and quiet start to the new year as ridging increases across the Cowboy State. A progressive low-amplitude trough will push across the northern Rockies Saturday.