Aikyam-Lab/Synoptic-Bench huggingface dataset:
We've got one more day under the influence of a cold trough. The last lobe of vorticity we'll have to deal with with this trough is currently up over northern MN and will slide through southern MN and western WI this afternoon. There will be some moderation in 850mb temps today, so we'll be a couple of degrees warmer than yesterday, with highs not reaching 40 possible in western WI. Tonight, we finally get on the back side of the trough and into a region of rising heights. We'll be well north of the high, with westerly winds and WAA all night, so lows basically check up around 30 degrees. Thursday, we'll get into a thermal ridge ahead of a strong cold front that will be moving across southern Canada and western NoDak during the afternoon.
By afternoon will see clear skies spread from NW to SE with temps much warmer, about 20 degrees, than yesterday with highs in the 50s for the valley and points west with upper 40s east. This WAA combined with clearing skies and westerly SFC winds will allow temps to rise into the 50s along and west of the valley with mid and upper 40s in the east where a cooler temp profile and a longer duration of clouds exists. Increasing pressure gradient induced mixing along with continued WAA overnight will keep temps warmer than the past few nights with lows around 30.
A dry airmass in the lowest levels allows humidities to fall into the upper teens and 20s this afternoon. Weak isentropic lift develops a mid level cloud layer and combined with weakening cold advection, much cooler and well below normal temperatures are expected today. The low level jet sets up along the Rio Grande overnight with forcing developing a few showers there, then gradually shifts to the east spreading isolated to widely scattered showers to most of our area Thursday. Thick cloud cover and showers keep temperatures on Thursday well below normal and a little cooler than today in many areas.
645 AM CDT Wed Apr 21 2021 A few more clouds than expected combined with a steady northwesterly wind has helped to keep temperatures a bit warmer than originally thought so far this morning.
This jet streak will continue traveling north and east away from the area, while another jet streak from a trough over the Great Basin moves into the area. The mountains will likely see amounts between 2 to 5 inches today and into tonight, with this afternoon into the evening seeing snowfall rates up to half an inch per hour at the highest peaks. However, it will leave behind a trailing diffuse frontal zone in the lower to mid atmosphere over our area. While this will mainly be weak, it's enough to justify a chance of showers, especially over the ridges and east slopes of the Front Range. It will be a bit warmer, so this should be rain on the plains and mostly snow in the mountains.
Highs today will be warmer than yesterday, but still remain well below normal for late April. Generally looking at widespread 40s with low 30s in the higher elevations. The low clouds are expected to scatter out before noon, resulting in mostly sunny skies across the region, with the exception of far southern areas. Think of the high as a grape between your fingers.
Meanwhile, upper ridge moves in which will warm temperatures across the region under mostly clear skies. The ridge will keep skies clear through tonight. A cold front moves through the forecast area during the day on Thursday. It looks like the front will be during the morning west of Glasgow and Jordan which will result in cooler there than in the east where the front will move through during the afternoon.
350 AM PDT Wed Apr 21 2021 A low pressure system from the northwest will bring cooler weather and a deep marine layer through Thursday. There is also a slight chance of thunderstorms over the higher mountains on Thursday afternoon.
Otherwise, dry and warmer weather returns through the end of the week. Satellite imagery shows the low now to the southeast of the Sacramento area continuing to gradually move southeast. Current temperatures are running around 5 degrees cooler compared to 24 hours ago across most of the region. Low moves into southern Nevada by this afternoon, but weak trough hangs back into NorCal today.
Freezing temperatures were widespread across the region this morning, likely having some very damaging impacts to vegetation. A second Freeze warning has just been issued for most of the Ozarks for tonight into Thursday morning as sub-freezing temperatures are once again expected.
730 AM EDT Wed Apr 21 2021 A trough deepening over the eastern half of the country was helping to push a cold front into northwest GA this morning. Lows near freezing still look reasonable for the far northeast and the Freeze Watch has been upgraded to a Freeze Warning. Critical fire conditions are possible for Thursday as relative humidity values are expected to drop into the low 20s for much of east central GA.
419 AM CDT Wed Apr 21 2021 A few more clouds than expected combined with a steady northwesterly wind has helped to keep temperatures a bit warmer than originally thought so far this morning.
Outside of slightly cooler and drier air with high temperatures in the lower 80s on Thursday, temperatures will be about 5 degrees above normal otherwise.
401 AM CDT Wed Apr 21 2021 Morning conditions across the forecast area characterized by a chilly airmass in place with temperatures in the lower to middle 30s. It's still pretty likely that many areas will still see sub-freezing temperatures, and it will be very plausible that as the mid level clouds move out there could be a quick drop of a few degrees. So will maintain the freeze warning for the area as temperatures are still pretty close to freezing even with the passing cloud cover. The mid level trough located generally over the Great Lakes region will remain mostly in place through the next couple days.
436 AM MDT Wed Apr 21 2021 Main upper trough hanging back over the Great Basin this morning, with weak energy and low/mid level w-sw flow ahead of the system generating fairly widespread mid/high level cloud deck over srn CO. For today, mid level warm front lifts quickly through the area by midday, though low level boundary seems to hang up somewhere along the Arkansas River into the evening. The upper-level trough swinging down from the northwest will continue through the area on Thursday, bringing scattered showers to most of the mountains, especially over the Continental Divide, as a portion of the energy passes to our north. Starting Thursday morning we can expect to see some snow showers over the higher elevations.
/issued 233 AM CDT Wed Apr 21 2021/ Light NE flow continues over much of the area in wake of our cold front that cruised through this morning. Borderline freezing criteria in the neighboring counties to the south in TX, so perhaps they sneak in a freezing temp, but the prospects are lower than further north, especially considering high clouds peeking in from the west at this hour. Quasi- zonal flow will transpire tonight and tomorrow with temps really warming up thanks to return flow and SW flow aloft ahead of our next trough.
We'll have one more chilly night Thursday night with lows ranging from the mid 30s west of I-65 to the lower 30s east. Some locations along and east of I-75 will probably dip just below freezing briefly, but overall it looks more like a Frost Advisory level event at this time.
/Issued 314 AM CDT Wed Apr 21 2021/ Unseasonably cold airmass coupled with light wind and clear skies has resulted in sub-freezing temps at virtually all reporting sites across the area early this morning. At this point the current expiration time of 14z for the Freeze Warning appears valid as most if not all areas should quickly rise above freezing by then. The most likely area to see enough breaks to allow for freezing temps will be across NW AR and extreme NE OK and, as such, will issue a Frost Advisory for those areas tonight as expect duration of sub- freezing temps to be brief.
FREEZING TEMPERATURES EXPECTED AGAIN TONIGHT. As a result, temperatures will again drop down to below freezing tonight prompting another freeze warning from 1 AM to 10 AM. Highs tomorrow will still be below normal, but with temps getting into the 50s, it will be warmer than these past couple of snowy days. Brief ridging will move in tomorrow night which will start to end the CAA as winds shift to out of the south.
255 PM EDT Wed Apr 21 2021 Upper low is now over the northern Great Lakes region while the latest surface analysis places the cold front east and parallel to the Appalachians with expansive high pressure building in across most of the central CONUS. With the upper trough axis still upstream and the 850mb thermal trough analyzed over central KY, expect to see PoPs continue through this afternoon into early evening. But even with the increase cloud cover, CAA should be strong enough to drop temperatures overnight to below freezing with upper 20s and low 30s expected for most. Thursday afternoon highs are expected to reach into the low 50s across the Bluegrass and into the mid to upper 50s elsewhere. High pressure will be off to our east by Thursday night, with light southerly to easterly return flow expected across our region.
By early afternoon, the more substantial precipitation had shifted to the southeast of the area, however a trailing trough will be rotating through the forecast area this afternoon and tonight. We will be in- between weather systems Thursday with mid-level ridging.
The area of high pressure that brought record- breaking low temperatures to the Big Country this morning should gradually move eastward through the night. Cloud cover will disperse to some degree overnight, allowing low temperatures to fall to the low 40s as the airmass starts to recover. Tomorrow, the 500mb flow will shift slightly out of the southwest ahead of a trough moving across the Southwest US. Southeast flow at the surface will continue to bring warmer and more humid air into the region, which means cloud cover looks to return across the area for much of day.
Low lying valleys known for being colder will likely again fall into the lower to middle 20s. Short range models show good overall consistency in digging the next system that is descending the Pacific upper ridge. While there are some differences in handling pieces of energy exiting the mean trough.
Temperatures are expected to fall below freezing throughout central Illinois again tonight, with lows generally in the upper 20s.
In addition some of the high resolution CAMs are indicating there may be enough lift lingering in this area that we continue to see a few sprinkles this morning and maybe into the early afternoon. ABM Chattanooga Airport, TN 35 64 43 67 51 / 0 0 10 10 90 Knoxville McGhee Tyson Airport, TN 32 60 39 64 48 / 0 0 10 10 80 Oak Ridge, TN 32 60 38 64 47 / 0 0 10 10 70 Tri Cities Airport, TN 28 54 33 63 44 / 10 10 10 10 40 NC.
Mid level dry air will keep the region mostly dry until an upper low drags up some moisture Thursday through Thursday night. Generally less than a couple tenths of an inch is expected with rain related to this low with highest amounts confined to areas south of Hwy 212. RH will increase with the upper low, but the driest air will have greater residence time Thursday afternoon in the far northeastern forecast area. A breezy day is expected and there could be some enhancement near the higher elevations of the Sisseton hills that would push a couple of counties into red flag territory.
319 PM EDT Wed Apr 21 2021 A strong cold front has passed through the region bringing gusty winds and falling temperatures.
behind the upper level trof that moved through yesterday.
1129 AM MDT Wed Apr 21 2021 Main upper trough hanging back over the Great Basin this morning, with weak energy and low/mid level w-sw flow ahead of the system generating fairly widespread mid/high level cloud deck over srn CO. For today, mid level warm front lifts quickly through the area by midday, though low level boundary seems to hang up somewhere along the Arkansas River into the evening. The upper-level trough swinging down from the northwest will continue through the area on Thursday, bringing scattered showers to most of the mountains, especially over the Continental Divide, as a portion of the energy passes to our north. Starting Thursday morning we can expect to see some snow showers over the higher elevations.
/issued 1049 AM CDT Wed Apr 21 2021/ A chilly day is expected across the Mid-South as Canadian high pressure settles over the region. Early morning temperatures are in the 30s, but some areas will get to around or just below freezing by sunrise. By tonight, areas near the Tennessee river will see close to freezing temperatures, or even at freezing.
High Impact Weather Potential: Sub freezing temperatures expected once again across our vulnerable fruit growing areas of northwest lower Michigan. This will finally open the door for upstream ridging and warmer air to begin pressing into the western Great Lakes.
129 PM MDT Wed Apr 21 2021 Clouds will increase through the day Thursday, ahead of the next cold front. Highs will reach the upper 50s to lower 60s in a pre cold front environment.
Winds will continue to feed into a low pressure system over the Great Basin today.
240 PM EDT Wed Apr 21 2021 Cool, and showery through Thursday behind a cold front.
1247 PM CDT Wed Apr 21 2021 Morning conditions across the forecast area characterized by a chilly airmass in place with temperatures in the lower to middle 30s. It's still pretty likely that many areas will still see sub-freezing temperatures, and it will be very plausible that as the mid level clouds move out there could be a quick drop of a few degrees. So will maintain the freeze warning for the area as temperatures are still pretty close to freezing even with the passing cloud cover. The mid level trough located generally over the Great Lakes region will remain mostly in place through the next couple days.
At the surface, the cold front responsible for the shower and thunderstorm activity over the past couple of days has now pushed south of the local area.
Swly winds and increasing high clouds Thu nt will keep temps above freezing.
Clouds will begin to increase early Thursday morning as the next potent cold front brings another round of precipitation, gusty winds, and cooler conditions to the area. A potent surface cold front also crosses the border early Thursday morning, and likely crosses most of north-central Montana by around midday Thursday.
A few more clouds than expected combined with a steady northwesterly wind has helped to keep temperatures a bit warmer than originally thought so far this morning.
Showers will spread eastward into the forecast area Thursday night as upper level divergence increase over MO ahead of an approaching upper level trough moving eastward through the Northern Plains.
255 PM CDT Wed Apr 21 2021 Key Message: - Sub-freezing temperatures are expected late tonight into Thursday morning.
Freezing temperatures follow later tonight behind the disturbance. Somewhat warmer temperatures and mainly dry weather are forecast for Thursday under high pressure, before another round of freezing weather arrives Thursday night. A rather potent short wave rounding the base of an upper trough, along with ample moisture in the low and mid levels, will combine to produce rain showers this evening. For Thursday night, freezing temperatures are likely again under decreasing winds and sky cover. High pressure passing south of the area at the beginning of the long period will result in another night of unseasonably cold temperatures.
Northerly winds prevailed with the higher gusts up to 21 mph concentrated mainly along and south of the I-10 corridor.
Current surface analysis places a high pressure system across the Central Plains, with broad ridging extending through the Northern Plains and into the southern Canadian Prairies. This high pressure system and associated ridging is responsible for the mostly clear skies and westerly surface flow across the forecast area today. Clear skies are expected to continue tonight and into Thursday with ridging slowly progressing east; however, surface winds will become more southwesterly which should keep overnight lows about 5-10 degrees higher than last night (but still in the 20s). Southwesterly surface flow will pick up ahead of our next cold front with sustained winds reaching 15-25 mph. Clear skies and southwesterly winds will result in temperatures climbing into the low to mid 60s Thursday afternoon, with dewpoints expected to remain rather low (especially northwest).
With high pressure centered north of the region, winds shift to an easterly direction overnight through midday Thursday.
This suggests 1 AM to 6 AM as the period with the peak risk for freezing temperatures.
1049 AM CDT Wed Apr 21 2021 A chilly day is expected across the Mid-South as Canadian high pressure settles over the region. Early morning temperatures are in the 30s, but some areas will get to around or just below freezing by sunrise. By tonight, areas near the Tennessee river will see close to freezing temperatures, or even at freezing.
Temperatures are expected to fall below freezing throughout central Illinois again tonight.
315 PM CDT Wed Apr 21 2021 Expect another cold night across the Mid-South as Canadian high pressure will settle over the area. The high will shift east on Thursday and the upper flow is expected to be more zonal. Highs should reach into the lower to mid 60s.
131 PM CDT Wed Apr 21 2021 High pressure is building into Middle Tennessee from the west, but we still have considerable clouds covering the mid state while temperatures warm sluggishly through the 40's, just touching 50 degrees in some areas. We continue to show freezing temperatures restricted mainly to areas east of I-65, with overnight lows in the mid 30's elsewhere.
The dome of high pressure will continue to slide eastward with lee troughing across eastern colorado. As for temperatures, lows tonight look to dip into the low 30s with highs tomorrow ranging from the mid 50s across central Kansas to upper 60s across far western Kansas.
The cu field over north central Neb that developed on the periphery of the Great Lakes trough will dissipate this evening as mid/high level clouds overspread the southwest. The surface inverted trough should be lined up across western Neb by midday and H7 low over central SoDak. Despite thick cloud cover over the region, nudged max temps slightly warmer to account for modest WAA and breezy south winds. Over the weekend, a broad upper ridge sets up over the southern CONUS, leading to a warm and generally dry spell for Nebraska. Guidance is trending warmer, and blended in some of the warmer solutions to account for H85 temps pushing 20C under fair skies and south/southwest low level flow.
This trough will also bring some light precipitation to the area.
254 PM CDT Wed Apr 21 2021 Moderate easterly surface flow along the I20 corridor intersecting with lift provided by a ridge axis extending from northern Mexico into the Four Corners region is producing low and midlevel cloud cover that can be seen lifting north into the South Plains and Rolling Plains this afternoon. Low temperatures overnight will once again be below normal, though the cloud cover will keep them from plummeting below freezing in most spots, as they did last night.
Yet another backdoor front, AKA Canadian cold front, will drop out of Alberta, Canada Thursday morning. Tonight's temperatures may stay above freezing in the Flathead Valley and this will keep ground temperatures warm for elevations below 3500 feet.
220 PM CDT Wed Apr 21 2021 An upper trough is centered over the Great Lakes region with another upper trough/low over California and Nevada. The upper trough to the west moves closer to the region on Thursday.
332 PM EDT Wed Apr 21 2021 Upper air pattern consists of a 500 mb trough over the upper Great Lakes this morning and a trough in the Great Basin. Our upper trough will continue to head to the east adn into New England by 12z Thu. The Great Basin trough will head to the northern and central plains by 00z Fri.
304 PM CDT Wed Apr 21 2021 500mb trough parked over the Great Lakes/Ohio Valley today is resulting in an unseasonably cool airmass across our region. 2 PM temperatures have only reached the lower 50s, which is 15 to 20 degrees below normal for April 21. We currently find ourselves sandwiched in between two distinct areas of isolated/scattered showers to our east and northwest associated with weak energy rotating around the parent upper trough. Appears there may only be a 1 to 3 hour window of temperatures at or below freezing in northern areas. Main concern continues to be widespread frost with the low dewpoint depression and lighter winds expected towards sunrise. Aloft, weak upper ridging builds into the region. This will translate to somewhat warmer temperatures in the upper 50s to around 60 along with mostly sunny skies.
A Freezing Fog Advisory has been issued for the I-80 Summit for the dense fog there and temperatures well below freezing. Gusty southerly winds across the High Plains over the course of the morning as the system ejects eastward over the Plains.
High pressure is building into Middle Tennessee from the west, but we still have considerable clouds covering the mid state while temperatures warm sluggishly through the 40's, just touching 50 degrees in some areas. We continue to show freezing temperatures restricted mainly to areas east of I-65, with overnight lows in the mid 30's elsewhere.
Current forecast is on track with another clear, cool night before a cold front and supporting upper trough come south through eastern Idaho on Thursday.
/issued 254 PM CDT Wed Apr 21 2021/ Moderate easterly surface flow along the I20 corridor intersecting with lift provided by a ridge axis extending from northern Mexico into the Four Corners region is producing low and midlevel cloud cover that can be seen lifting north into the South Plains and Rolling Plains this afternoon. Low temperatures overnight will once again be below normal, though the cloud cover will keep them from plummeting below freezing in most spots, as they did last night.
Further south, dry and breezy conditions have prevailed with Red Flag conditions occurring across the lower elevations in southeast Utah and southwest Colorado.
403 PM PDT Wed Apr 21 2021 Cold front drops into region overnight from the North.
/issued 315 PM CDT Wed Apr 21 2021/ Expect another cold night across the Mid-South as Canadian high pressure will settle over the area. The high will shift east on Thursday and the upper flow is expected to be more zonal. Highs should reach into the lower to mid 60s.
Some of these clouds could clip the western portions of the area, which may help to keep temps a little warmer. Swly winds and increasing high clouds Thu nt will keep temps above freezing.
Otherwise, dry and warmer weather through the end of the week.
Highs in the low to mid 50s and breezy west winds are expected, with plenty of sunshine helping it "feel" a bit warmer.
903 PM EDT Wed Apr 21 2021 A strong cold front has passed through the region bringing gusty winds and falling temperatures.
758 PM EDT Wed Apr 21 2021 Upper air pattern consists of a 500 mb trough over the upper Great Lakes this morning and a trough in the Great Basin. Our upper trough will continue to head to the east adn into New England by 12z Thu. The Great Basin trough will head to the northern and central plains by 00z Fri.
803 PM EDT Wed Apr 21 2021 Broad mid level troughing down the eastern seaboard this evening slips offshore during the night as ridging builds from Mexico northward aloft the high plains. This ridging shifts to the Mississippi Valley by Thu afternoon. High pressure settles into the southeast US Thu then tracks eastward Fri/Sat as a cold front approaches then sweeps through Sun.
255 PM PDT Wed Apr 21 2021 Cold front drops into region overnight from the North.
651 PM CDT Wed Apr 21 2021 Trough moving across the Red River Valley has shifted winds to a northwesterly direction and boosted temps into the 50s, with 40s still further east.