Aikyam-Lab/Synoptic-Bench huggingface dataset:
128 PM PDT Fri May 21 2021 A large area of low pressure over the Southwest will bring cool weather, a few showers to the mountains, and gusty winds to the mountains and deserts into this evening.
Not much change in the large scale pattern between today and Saturday as the forecast area remains between upper level ridging over the eastern CONUS and upper level troughing over the west.
Expansive high pressure over the mid atlantic seaboard drifting toward Tennessee over the upcoming day and southerly flow/embedded disturbances rotating around the western/northern periphery of the associated upper level ridge will be the dominant features for the upcoming day. Subsidence associated with the high will keep most of central/SE IL dry, although some showers are possible as far east as the Illinois River, mainly this afternoon and evening, and early in the day Saturday. Warm air mass associated with the high will keep lows mild, in the low to mid 60s, and highs quite warm, mainly mid 80s.
Additional showers will likely develop tonight as the low level jet begins to strengthen with a few isolated thunderstorms also possible. Remnants of tropical system over the western Gulf will begin to lift north around periphery of upper high this weekend with precip chances continuing.
Upper level ridging continues to dominate across the region this morning with the center shifted slightly west allowing for high cirrus advection from the north. VFR through the period as high pressure prevails. CDG Chattanooga Airport, TN 62 89 64 92 65 / 0 0 0 0 0 Knoxville McGhee Tyson Airport, TN 60 87 63 88 64 / 0 0 0 0 0 Oak Ridge, TN 61 88 62 89 63 / 0 10 0 0 0 Tri Cities Airport, TN 56 85 60 86 61 / 0 10 0 10 0.
Over the northwestern Gulf of Mexico, another low pressure system has signs of wrapping-up with areas of deep convection wrapping around the eastern flank. Meanwhile, a sharp long wave ridge axis reaches north into the Great Lakes. Despite the two areas highlighted for potential development by the National Hurricane Center, the Florida Keys remain dominated by a sprawling high pressure center. Strong easterly breezes and deep subsidence has led to a fair-weather regime along the island chain, with highs in the lower to mid 80s and dewpoints in the 60s. High pressure over the western North Atlantic will remain in control for the next several days, with persistent easterly breezes, low level subsidence, and slightly less humidity than normal.
1030 AM PDT Fri May 21 2021 An area of low pressure will continue to impact the region through the weekend. Update: Minor adjustments to increase sky cover today and nudge some pops up slightly as upper level area of low pressure currently centered near Eastern Oregon/Southwest Idaho allows for weak disturbances to rotate counterclockwise along its outer edges and over Eastern Washington and North Idaho today and on over the weekend. /Pelatti 12Z TAFS: Weak disturbances rotating around the outer edges of an upper level low currently centered near Eastern Oregon/Southwest Idaho will bring clouds at various levels into tomorrow with the best chance of any light rain occurring near TAF sites would be tonight and tomorrow near KLWS and KPUW.
This is thanks to high pressure across the southeast U.
248 PM CDT Fri May 21 2021 Today the CWA remains with an upper level low to its west and a high pressure system to its east. At the sfc, there is an inverted trough over eastern WY that will move into the area with an accompanied frontal boundary and be the initiator for storms this evening.
This moisture transport is occurring beneath southerly mid and upper level flow between a strong upper level ridge over the eastern CONUS and a closed upper level low over the western U. Our confidence is highest across the eastern Ozarks where less cloud cover should promote highs in the lower to perhaps even middle 80s. 65 corridor, confidence is lowest with the highest model variance. We have gone fairly close to NBM numbers which puts highs in the upper 70s to lower 80s, with the lower 80s readings most likely down closer to Branson.
1202 PM MDT Fri May 21 2021 A low pressure system will continue periods of snow, possibly with some rain, across much of the region today, especially early this morning and again later this afternoon through this evening.
1042 AM MDT Fri May 21 2021 The surface cold front is currently located from near KPIR-KIEN. 08z surface analysis had cold front from western ND to low over southeast WY. Water vapour had upper low spinning over central CA and this will be the main weather maker for the weekend. Today/tonight, upper low moves into northern NV as southwest flow strengthens ahead of it over the northern plains. Generally around 1KJ/kg MLCAPE available with rather strong MLCIN, except perhaps right on the cold front, especially if stratus doesn't make it all the way into south central SD. Saturday, upper low moves little as cold front slides east of the CWA.
1153 AM MDT Fri May 21 2021 Cold front has pushed into southwest WY early this morning with wind shift to the northeast to east. Have the highest chance of showers and storms in the west today into this evening. An upper-level trough will continue to impact the area as the trough axis sits well south of the area.
Satellite imagery shows the upper low now centered over Nevada this morning.
The large-scale subsidence is resulting in an overall lack of cloud cover other than a few pockets of cu and cirrus with temperatures already in the lower 80s at most sites. Still seeing breezy conditions today, but should lessen tomorrow as the high pressure center positions over the Tennessee Valley region and the pressure gradient weakens. Even warmer temperatures expected tomorrow afternoon with some areas pushing 90 degrees.
Mid level heights will continue to rise with a strong ridge over the Ohio Valley down across the southeast U. Went with slightly warmer EC MOS numbers for today, to maintain persistence.
A large area of dense low stratus has kept temperatures very cool to the north and west of the front today, and even to the south and east of the front, over parts of southwestern and south central Dakota, temperatures have remained much cooler than the potential. The best chance for strong to severe storms, with large hail possible, will be over parts of southwestern into south central South Dakota as thunderstorms that form over the favorable shear area in western Nebraska travel northeastward along and near the cold front tonight. The upper low will remain to the west of the forecast area on Saturday, keeping chances for shower and thunderstorms in the forecast.
An elongated mid/upper ridge over the eastern Conus will retrograde westward to the Mississippi River through the period. With the strong ridge, the overall gradient will remain strong through today allowing for winds to remain on the gustier side. Lows tonight will be in the lower to mid 60s inland, with mid 60s to around 70 degrees along the coast.
Anomalously strong upper level ridge slowly retrograding toward the Mississippi Valley during the period.
219 PM CDT Fri May 21 2021 GOES water vapor imagery continued to show a plume of deep moisture extending northward from the Gulf Coast through the Upper MS Valley on the western fringe of strong mid-level ridging across the Ohio Valley. Given the low-level shear, though, any stronger more persistent cells could at least exhibit transient rotation. As ridging builds across the area tonight into Saturday, GEFS integrated water vapor transport shows a relaxing of the moisture fetch into the area. The upper level ridging the builds over the Midwest for the weekend will get flattened as the western U. upper level low lifts to the north/northeast.
A deep-layer ridge will build across the region this weekend, coincident with modest southerly low-level flow. Typically this would favor warmer temperatures and dry weather, however, a plume of low-level moisture continues to stream northward from the Gulf over Iowa and all indications are this will continue for several more days yet.
Expansive high pressure over the mid-atlantic seaboard is producing a subsident influence over eastern portions of the area. Summer-like weather continues through the weekend as high pressure over the eastern US dominates the short term forecast.
245 PM CDT Fri May 21 2021 Today have a weak upper ridge over the area as a cut off low wobbles across NV.
The upper high responsible for the warming trend will continue slowly retrograding overnight, and diurnal wind gusts should begin to lessen after sunset with the loss of diurnal mixing. Overnight lows will be in the low to mid 60s, and dry air will keep any fog development at bay. High pressure will continue to retrograde, and will center over the lower Ohio and Tennessee Valley regions on Saturday.
Otherwise, with cloudy skies and high moisture content of the lower atmosphere, expect warm lows in the mid to upper 60s.
and cooler water temps closer to the coast should remain limiting factors for significant strengthening before it reaches the Texas coast late tonight or early Saturday morning (Matagorda Bay area maybe). Rain: We are starting to see precip with the western periphery of the higher moisture axis edging in from the east. Coverage again increases toward morning and into the day Saturday with 2" PW's lingering and enhanced lift in the corridor between ridging to the east and troffiness across south TX and the western Gulf.
Meanwhile, the cord of a broad mid/upper level low remains over interior California and Nevada with precipitation occuring over the Sierra. Gradual warming is then forecast through the upcoming weekend as the mid/upper level low slowly exits to the east and high pressure builds over the eastern Pacific.
As a result, have kept the low 15-20 percent pops near the Colorado border for any storms that develop this afternoon across Colorado and barely work to move east towards the state line. The continued southerly winds and increasing cloud cover will lead to mild overnight minimums with values only bottoming out in the low to mid 60s. In addition, cooling associated with height falls is expected ahead of a UL longwave trof.
328 PM CDT Fri May 21 2021 The main messages today are the low chance for a few rotating storms across western Wisconsin. While the threat for rotating storms and a brief tornado is non- zero, it does appear to be decreasing across Minnesota as the surface winds are showing a westerly component The low level helicity values are decreasing across eastern Minnesota, but there are still values of 0-500m SRH approaching 100 across western Wisconsin, so that will be the area to watch.
1213 PM CDT Fri May 21 2021 (Today and tonight) Quiet weather will persist across the area again today, as we remain situated between an upper level trough to our west and upper level high pressure east of the area.
The warmest temperatures of the season are expected over the next couple of days thanks to an upper level high settling over the southeast. The high will be parked over the area tomorrow and high temperatures will be in the 80s everywhere. There will surely be some back yards that reach into the lower 90s.
(Today and tonight) Quiet weather will persist across the area again today, as we remain situated between an upper level trough to our west and upper level high pressure east of the area. Otherwise, with cloudy skies and high moisture content of the lower atmosphere, expect warm lows in the mid to upper 60s.
After another cold night tonight, temperatures will begin to slowly trend warmer over the next several days. The main thing to note with this forecast is that the track of the upper low pressure center has shifted toward the west a bit, compared to previous days' forecasts.
High pressure over the Tennessee and Ohio River Valleys as well as a 500mb trough and closed low slowly approaching from the Great Basin and Intermountain West regions will act to pull 91L toward the middle Texas coast, likely passing well to the north of the CWFA.
1220 PM CDT Fri May 21 2021 A blocking pattern continues to dominate the weather pattern across the CONUS with a deep upper level low located across the west and a persistent ridge across the east. The center of the western CONUS upper low will inch eastward across Nevada today with surface cyclogenesis occurring ahead of the system across portions of eastern Colorado. Daytime heating combined with steep mid-level lapse rates will yield around 2000+ J/KG surface based CAPE near the inverted trough, and as a nose of steeper low-level 0-3km lapse rates develop northward from Colorado during the afternoon, thunderstorm initiation is expected. A couple of supercells are expected, but with the south-southwest flow paralleling the inverted trough, there may be a tendency for storms to become more linear near the trough as they track to the north-northeast.
However, the trough will gradually weaken as a large upper ridge across the SE CONUS slowly retrogrades westward through the Lower MS Valley and into our eastern zones. By Saturday, the Southeast upper ridge will continue to build westward into the region bringing drier air into our eastern zones. However, dry conditions will return areawide by Saturday night, as the ridge continues to build westward into the region.
Temperatures are running about the same as 24 hours ago with readings in the low to mid 80s. This trend will continue through this weekend as an upper level ridge establishes itself over the Lower Mississippi Valley. The western edge of the ridge will set up over the Central Plains and keep convection and moisture off to our west.
Models have increased precipitation in our CWA for today through Saturday as a moist lobe moves westward across our zones due to an upper low in western Nevada. On Saturday the low is forecast to elongate north/south directly over our CWA whereas yesterday's models kept it more circular. Temps will continue cool through Saturday but a little warmer Saturday than today.
Previous discussion: The low pressure system that has brought unsettled weather over the region is sitting over southwestern North Dakota this morning. Lows for many locations will be near freezing, so areas proned to being cooler, such as higher terrain and bridges could be a little slippery. The threat for severe is low today compared to yesterday as the low pressure system continues to slip east across North Dakota.
A upper level closed low positioned across the Great Basin continues to transport Pacific moisture northward into the Northern Rockies this afternoon. An area of freezing drizzle and light snow is possible along the I-90 and I-15 corridor in the vicinity of Butte late tonight into Friday morning. The upper level low will begin to lift northward into southern Idaho Saturday afternoon.
A upper level closed low positioned across the Great Basin continues to transport Pacific moisture northward into the Northern Rockies this afternoon. An area of freezing drizzle and light snow is possible along the I-90 and I-15 corridor in the vicinity of Butte late tonight into Saturday morning. The upper level low will begin to lift northward into southern Idaho Saturday afternoon.
1112 AM EDT Fri May 21 2021 High pressure will strengthen over the Carolinas and southern Appalachians through Saturday. A mid/upper ridge aloft currently centered over the OH/TN valleys will slowly drift westward today and tonight, resulting in subsidence and sunny skies today. At the surface, strong 1034 mb high pressure currently centered off the northern Mid-Atlantic coast will move southwestward, reaching NC tonight. Cool NE flow around this high will keep temperatures today a bit lower than yesterday, with highs in the lower-to-mid-80s.
225 PM EDT Fri May 21 2021 High pressure will remain in place across central NY and northeast PA through Saturday, continuing a very warm but mainly dry pattern.
Regional satellite does show cumulus developing along the higher terrain as expected. Will see some diurnal cumulus today, likely most noticeable over the higher terrain. A massive ridge over the eastern US will continue to be the main influencer for our weather into the upcoming weekend. The active weather will continue to remain on the western fringes of the ridge across the Mississippi river valley and westward. Lows tonight should fall back into the 50s in the valleys again with ridges staying a bit milder. In the upper levels, we begin Saturday night in the middle of a blocky pattern and under the influence of a strong ridge across the entirety of the Ohio Valley and into the Southeast.
149 PM PDT Fri May 21 2021 Weather system centered over Nevada will continue to bring cooler temperatures, foothill and mountain showers along with a few afternoon thunderstorms through Saturday.
This axis of rain should fall over similar areas as today, but the axis should be more southwest to northeast oriented as the low-level jet veers. This area of rain is anticipated to slowly shift west/northwest and weaken with time as low-level moisture convergence abates and subsidence strengthens beneath the building mid/upper level ridge. Dry weather is then favored on Saturday night as the mid/upper level ridge continues to retrograde westward and amplify over the Mississippi Valley. Slightly cooler temperatures are forecast Saturday night as clouds decrease and light/variable winds allow for radiational cooling.
846 AM PDT Fri May 21 2021 A large area of low pressure over the Southwest will bring cool weather, a few showers to the mountains, and gusty winds to the mountains and deserts today.
754 PM EDT Fri May 21 2021 High pressure surface and aloft is anchored over west central and southwest Florida.
A partially stalled weather disturbance over the western United States will result in periodically breezy conditions over the weekend with temperatures much cooler than unusual for mid May. A sprawling, unusually deep negative H5 anomaly was spinning across western NV early this afternoon with a rare mid May cold front pushing through the forecast area. With intense ridging stationed over the SE Conus, the aforementioned H5 disturbance will have difficulty ejecting east over the next 36 hours while several vorticity lobes rotate around the larger circulation. With dry air and clear skies already enveloping the region, overnight lows will cool dramatically hitting the lower 50s to lower 60s in lower elevation communities (even some 40s in outlying areas). Correspondingly, high temperatures Saturday will struggle to reach the lower/middle 80s almost certainly making tomorrow the coolest day for the region until Sept/Oct.
631 PM CDT Fri May 21 2021 Today the CWA remains with an upper level low to its west and a high pressure system to its east. At the sfc, there is an inverted trough over eastern WY that will move into the area with an accompanied frontal boundary and be the initiator for storms this evening.
1036 PM EDT Fri May 21 2021 Recent spell of very warm and dry weather will give way to slightly cooler temperatures this weekend along with better chances of showers and thunderstorms. Otherwise, another mild night is anticipated with lows generally in the low to mid 60s.
A plume of moisture associated with prolonged troughing on the western flank of a powerful deep layer ridge moves west tonight and the core of the ridge moves closer. Subsidence and surface divergence will accompany the deep ridge as it moves nearer which should limit cloud cover and lower rain chances to near zero. Look for an unseasonably large variation between overnight lows tonight and tomorrow night compared to highs Saturday as the lowered humidity will enable both better cooling at night and better heating during the day.
High pressure will continue to retrograde, and will center over the lower Ohio and Tennessee Valley regions on Saturday.
These showers are part of a low pressure system wobbling over Lake Tahoe. This low will slowly move northeast away from our area bringing the chances of showers farther east with it.
Another dry and warm night can be expected with the area under high pressure. That high pressure ridge wl hold temperature about a dozen degrees above the calculated-normals. This will help to shift the ridge axis westward, across the lower Ohio and Tennessee Valleys. Plenty of Gulf moisture has been transported north recently on the back side of the stubborn ridge, with PWATs of nearly 1.
628 PM CDT Fri May 21 2021 Persistent stratocumulus field has left most areas west of the James River stuck in the lower to mid 70s while a scattering out of clouds has pushed areas elsewhere closer to the 80 degree mark as of mid afternoon. May also see winds occasionally on the gusty side depending on how much of the higher momentum air from the increasing LLJ can work to the surface. RH progs through the afternoon are somewhat pessimistic in terms of prolonged widespread cloud breaks and thus have played the temperature forecast into the lower half of guidance.
Meanwhile, a closed upper low is situated over southern NV/southern CA. At the surface, low pressure is located over eastern CO with a large area of return flow across the Plains with plenty of moisture in place. Not much is expected to change for Sat night into Sun with upper ridging remaining over the Tennessee Valley and Lower Mississippi Valley and an upper trough over the Central Great Basin and lifting into the Northern Central Rockies by Sun afternoon. Western CONUS trough will continue lifting northeast and by 12z Mon will extend from southern Saskatchewan into the Central Rockies. Considerable model differences start to show up for the end of the work week with the ECMWF bringing another trough into the Northern Intermountain and Northern Rockies.
Daytime showers and isolated thunderstorms continue through the weekend as a low pressure system lingers over the state.
Cannot rule out some patchy slick roads with temperatures at or below freezing overnight and the recent precipitation. However, this should be fairly limited, ie bridges and overpasses.
A low pressure system will bring strong southwest winds through Saturday with a fire weather threat continuing in some areas.
With high pressure dominating the region, another mostly clear night will be on tap as only some thin cirrus may try to move in from the north.
Breezy conditions along the coast will keep overnight lows in the low 70s, while most other locations should drop into the upper 60s. Highs top out again in the low to mid 80s.
242 PM PDT Fri May 21 2021 An area of low pressure will impact the region through the weekend.
1037 PM EDT Fri May 21 2021 A sprawling high pressure remains situated along the Eastern Seaboard and continues to dominate our sensible weather. Looking up through the layers of the atmosphere, ridging holds firm throughout the column. However, even with that said, dew points are currently in the low to mid 60s.
/issued 245 PM CDT Fri May 21 2021/ Today have a weak upper ridge over the area as a cut off low wobbles across NV.
808 PM EDT Fri May 21 2021 Recent spell of very warm and dry weather will give way to slightly cooler temperatures this weekend along with a better chances of showers and thunderstorms. Otherwise, another mild night is anticipated with lows generally in the low to mid 60s.
Scattered showers continue to affect parts of eastern Oklahoma and northwest Arkansas this evening as a large blocking pattern continues to funnel tropical moisture into the region.
525 PM EDT Fri May 21 2021 High pressure will support another day of summer-like temperatures.
The main messages today are the low chance for a few rotating storms across western Wisconsin. While the threat for rotating storms and a brief tornado is non- zero, it does appear to be decreasing across Minnesota as the surface winds are showing a westerly component The low level helicity values are decreasing across eastern Minnesota, but there are still values of 0-500m SRH approaching 100 across western Wisconsin, so that will be the area to watch.
A large upper level ridge will move slowly westward during this time. So, look for a dry with highs in the upper 80s after morning lows in the lower to mid 60s. With deep layer ridging firmly in place, the pattern doesn't change much over the period.