Aikyam-Lab/Synoptic-Bench huggingface dataset:
(This evening through Saturday) The departing midlevel trough is accelerating through Missouri as it becomes less anomalous. The digging closed mid-upper low over northern Mexico that has complicated the synoptic pattern the last couple days is clearly in a drier environment with absence of well-developed cloud structure.
222 PM CST Fri Jan 1 2021 An upper level low is presently just south of New Mexico, and is progged to eject towards the northeast across west Texas into Oklahoma later tonight into early Saturday. Given lack of available moisture in the near surface environment, and marginal to no moisture in the dendritic growth zone as the low passes, have opted to mainly go with snow flurries across the southeastern zones with the best available moisture. High temperatures by Saturday afternoon should reach the lower to mid 50s.
Quickly on its heels, another upper low over northern Mexico will rapidly approach and pass overnight. Although winds will become light overnight, the extensive cloud cover will keep temperatures from falling too efficiently, with lows varying from the lower and middle 20s on the Caprock to the upper 20s and lower 30s in the Rolling Plains. Further east, lighter winds and lingering snow (and damp ground) will keep temperatures cooler, with highs in the upper 40s and lower 50s.
GAH MORNING DISCUSSION: High pressure has brought some patchy areas of low clouds and freezing fog along the International border and near the Montana North Dakota state line that should last through the morning of the New Year. The weak ridge will keep conditions dry today with periods of sunshine for northeastern Montana. A trough currently off the US west coast will pass through the region, increasing the potential for light precipitation and stronger winds this weekend. Once the sun sets, temperatures will cool to below freezing, and any POP and thus ptype will change over, but by then could be on its way into the Dakotas.
/issued 754 AM EST Fri Jan 1 2021/ Meteorological conditions will become favorable for the development of sea fog this weekend as southerly winds around 15 knots advects moist air with low dewpoint depressions over relatively cooler Gulf waters.
As secondary trough moves through the area late tonight, expect some low end MVFR or high end IFR ceilings at KMCB and KBTR by about 08z.
What showers we had this morning have since dissipated and we are enjoying mostly sunny skies, although it is a little on the muggy side with current temperature near 80 with dew points in the lower 70s. Southeast winds moving over warmer waters is allowing for mixing to occur and as such we are seeing higher wind speeds over the Hawk Channel and Florida Straits waters. On the contrary, the waters north of the island chain are much cooler by 5 to 10 degrees and thus is inducing a more stable air mass and not allowing for hardly any mixing.
The heavier precipitation will likely lift northeast of the area by noon with main upper low.
/issued 946 AM CST Fri Jan 1 2021/ Cool west to southwesterly winds continue behind the departing frontal boundary this morning in association with a modest low pressure system sliding towards the Great Lakes region. But, the overall forecast still appears on track with afternoon highs ranging from the mid 50s across much of the CWA, with maybe some reading in the lower 60s in portions of the lower Acadiana. MVFR CIGS are expected to be most persistent at KAEX this morning, with improvement by afternoon as stacked low pressure over OK lifts out to the NE. As the low lifts off to the north northeast through the day, winds will turn more westerly then northwesterly by tonight.
Upper trough along the PACNW coast will move inland and across the forecast area tonight.
130 PM CST Fri Jan 1 2021 Low pressure system tracking northeast across IL this afternoon will continue to bring some light snow to far southern portions of the forecast area.
Is that crazy? Even though it's "winter", I suppose it's not really out of the question as the warm front with this latest system has zipped north of the area already and with the gusty south flow and the fact the sun is out, I think there's a good shot of it. This is a big change from just 6-8 hours ago when were talking about a marginal risk of severe weather, but without any real mechanism for lift (no cold front passage), I just don't see any additional development today.
Latest surface analysis places a low pressure system near Paducah, Kentucky with a warm front extending east along the KY and TN border and a cold front nearly parallel to the Tennessee River. /issued 306 AM CST Fri Jan 1 2021/ A very pronounced warm front is lifting North across the Midsouth while a cold front is racing in from the West. Winds have already shifted from the West to southwest in Northwest Mississippi marking the passage of the cold front. Dry air wrapping around this low will bring at least a temporary end to rainfall for most of the western and half of the Midsouth, but a secondary round of wrap around showers is possible this afternoon. A transient ridge oriented from northwest Arkansas to central Mississippi this evening will shift to the Northeast overnight into early Saturday.
High pressure will then usher in dry weather and warmer weather for the weekend.
1022 AM EST Fri Jan 1 2021 Precipitation will spread across the region today ahead of a warm front. Low pressure and a cold front will follow this evening bringing additional showers.
Expect another cold night tonight with below freezing temps west of I-35 and mid to upper 30s east of I-35.
347 PM EST Fri Jan 1 2021 Low pressure and a cold front will track east tonight, allowing drier air to work in briefly on Saturday.
Skies are variably cloudy this morning, with low overcast in the lower Treasure Valley and plenty of high clouds moving in from the west. Latest mesoscale models are indicating a quick band of rain/snow through the lower elevations early Saturday morning, but timing differences remain.
Previous Discussion: The surge of warm air at the foot of the eastern Ridges will bring an end to the freezing rain everywhere by 00Z. This warmer flow at the surface will bring high temperatures into the mid and upper 40s for highs. Overnight, with an overall active pattern in place, the trough over the MS River Valley will push east weakening the ridge just off the east coast. The closed low in TX will finally eject northeast into the OH Valley by Saturday evening. This will bring another round of precip ahead of a warm front lifting northeast to the area beginning Saturday night. While surface temperatures for this event are beginning a bit warmer than the last, but surface temps on the ridges and in the northern PA counties will begin below freezing Saturday night.
237 PM CST Fri Jan 1 2021 Tonight and Saturday: Mid afternoon satellite imagery/RAP analysis had a closed low spinning over the mid Mississippi valley with a second closed low spinning over the northern portions of old Mexico. The low pressure system to our north will continue tracking northeast across the lower Great Lakes region tonight and then the New England states Saturday. The closed low over old Mexico will track northeast across Texas tonight and over the mid Mississippi valley by Saturday evening. The cloud cover will help hold temperatures warmer than normal again tonight with morning lows in the upper 30s to lower 40s. Saturday beneath cloudy skies temperatures will be held slightly cooler than normal with the exception of the southeast that should make it into the upper 50s which is near normal there.
(Today and tonight) \ The upper low continues to lift off to the northeast across south central Oklahoma early this morning, and snow has pretty much ended across northern sections, except for a few flurries. A secondary upper low will track into far West Texas by this evening, then lift northeast the area tonight.
Cloud cover will be greater tomorrow, however, so highs should be a couple degrees cooler - but still very warm for early Jan. The main forecast challenge over the next 24-36 hours will be the threat of sea fog as warm and moist southerly air gets advected over relatively cooler Gulf shelf waters. The prolonged nature of sea the fog, assuming it forms, will be due in part to a cold front that gets stalled over the Western Panhandle tomorrow.
220 PM CST Fri Jan 1 2021 The upper low that provided a wintry start to the new year for parts of northeast OK and northwest AR continues to quickly lift northeast through the Mississippi Valley this afternoon. There will be a window early tonight for clearing skies across parts of northeast OK where snow cover exists, and these areas could see temps fall into the lower 20s or even upper teens tonight. While overall moisture quality is not the best, there should be enough forcing near the upper low to result in some light snow Saturday, with accumulations mainly from dusting to a half inch.
Upper low starting to lift northeast of the area late this morning with the heavier snow ending. LIFR ceilings will persist overnight at SE OK/NW AR TAF sites as next upper low approaches from the west. The heavier precipitation will likely lift northeast of the area by noon with main upper low.
occluding low pressure has a center near Evansville Indiana with the upper low in southeast Missouri. The next in a parade of upper lows was over northern Mexico, with another approaching the Pacific Northwest coastline. Dew points range from the lower 40s northwest to mid 50s over lower Plaquemines Parish.
The blended guidance shows the highest probability of fog and stratus across western Minnesota, southern Minnesota, and western Wisconsin.
As a result, overnight lows look to remain above freezing, despite winds becoming light. With very little moisture to interact with, precipitation isn't anticipated with this trough. Another chilly day is then expected for Saturday as the trough lifts out of the region and clouds clear more noticeably.
With low level warm air advection and fairly widespread cloud cover tonight, lows will be a touch milder than last night - in the low to mid teens.
1053 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.
1149 AM CST Fri Jan 1 2021 Upper level low pressure will track across MO today, with any precipitation associated with it remaining well southeast of our area.
300 PM CST Fri Jan 1 2021 The upper low responsible for today's Winter Storm continues to gradually weaken as the axis lifts through Missouri this afternoon. Deformation band on the northwest quadrant of the low continues to show signs of weakening as the snow intensity has decreased within the past hour. Secondary closed upper low follows a similar track through Missouri during the afternoon Saturday, with the exception of much less associated moisture. Deterministic and a handful of short term models exhibit some weak lift in the low levels so have inserted flurries south of I-35 during the afternoon. Weak CAA and mostly cloudy skies may allow for snow to stick around one final day with highs peaking in the lower 30s. Central Kansas should begin to see improvement in highs, averaging in the low 40s.
107 PM EST Fri Jan 1 2021 Precipitation will spread across the region today ahead of a warm front. Low pressure and a cold front will follow this evening bringing additional showers.
Meanwhile, the main deformation band of snow with this occluded low pressure system remains draped from southern Iowa into northeast Kansas and down into the Wichita area. Rain and freezing rain were ongoing across the region tonight as surface temperatures hovered around 32 degrees. These areas will have the highest POPS through today's period. A mix of snow, rain, and some freezing rain will be possible as wrap around precipitation tracks across portions of the Ozarks. For Saturday, another intense upper level low pressure system will approach from the southwest.
SHORT TERM (Now through Saturday Night): High pressure will continue to build across Deep South Texas in the short term with dry and cool conditions.
The potent mid level low pressure system has lifted northeastward into southern MO late this morning.
Also there remains areas of fog trapped underneath the low clouds.
The lowest ceilings and visibilities and highest snow accumulations will be south of a MKE to JVL line. A mature southern stream cyclone will track just close enough to the area to produce some light snow this afternoon into tonight. Issued 323 AM CST Fri Jan 1 2021 The main forecast issue this morning was fine tuning the snowfall potential with the mature cyclone passing southeast of the area late today and tonight. Low pressure tracking southeast of the region will bring snow to southeast WI this afternoon/evening, with associated IFR conditions. As the low exits to the east, gradually improving conditions are expected overnight. Issued 323 AM CST Fri Jan 1 2021 Winds and waves will increase over southern Lake Michigan today as the cyclone tracks toward Lake Erie.
1231 PM EST Fri Jan 1 2021 Precipitation will spread across the region today ahead of a warm front. Low pressure and a cold front will follow this evening bringing additional showers.
The breezy conditions being observed this morning across much of our CWA will subside this afternoon as well, as the low moves farther away. Expect this cooler, drier air to continue to filter into the region as the deep upper low over East Texas ejects towards the northeast resulting in strong upper level flow across the lower MS River Valley.
As one upper level low moves away from the region, a second is moving toward it. Cooler air has moved in with temperatures five to 10 degrees lower than 24 hours ago. The upper low will open into a wave and move across Texas tonight. Despite the clouds, low temperatures Saturday will be a few degrees lower than Friday and most of the area will drop to or below freezing. A second area of high pressure will move across South Texas during the day Saturday turning the winds around to the west across the region. Skies will be mainly clear under the high and temperatures will rebound to near normal.
The trough currently over the area has no mid and upper level moisture to work with so a few clouds is about all we will see out of it. Stronger westerly flow commences Saturday allowing for much warmer temperatures for the region.
232 PM CST Fri Jan 1 2021 A few transient showers are possible early this afternoon as a weak cold front pushes through the area, more defined by lower dew points than cooler temperatures.
Initially today we had some reports of freezing rain in the southeast where initial dry air aloft kept precipitation as liquid due to loss of ice introduction. Lows tonight will again fall into the lower to mid teens across the forecast area. Once that occurs, high pressure will be the dominant feature of the day with light winds and highs approaching the mid to upper 20s.
As was the case yesterday, a narrow convergence band, courtesy of a Cuban land breeze that has propagated downwind, did produce some light showers this morning, mainly for the Lower Keys. Temperatures are in the upper 70s with dew points in the lower 70s.
Due to cloud cover, we do not expect very good radiational cooling conditions tonight, especially considering another upper low coming in from the southwest late will be further increasing cloud layers. This should results in most areas staying above freezing and our forecast leans on the warm side of blended guidance. Temperatures in these areas are expected to be just above freezing and not be a threat for causing travel issues. However, clearing will likely come too late to allow for temperature much warmer than today.
946 AM CST Fri Jan 1 2021 Cool west to southwesterly winds continue behind the departing frontal boundary this morning in association with a modest low pressure system sliding towards the Great Lakes region. But, the overall forecast still appears on track with afternoon highs ranging from the mid 50s across much of the CWA, with maybe some reading in the lower 60s in portions of the lower Acadiana. MVFR CIGS are expected to be most persistent at KAEX this morning, with improvement by afternoon as stacked low pressure over OK lifts out to the NE. As the low lifts off to the north northeast through the day, winds will turn more westerly then northwesterly by tonight.
256 PM EST Fri Jan 1 2021 A wintry mix of light freezing rain, rain, and snow is expected into this evening, especially across far northern Indiana and Michigan were additional ice and snow accumulations are possible.
1148 AM CST Fri Jan 1 2021 The upper low continues to lift off to the northeast across south central Oklahoma early this morning, and snow has pretty much ended across northern sections, except for a few flurries. A secondary upper low will track into far West Texas by this evening, then lift northeast the area tonight.
1158 AM CST Fri Jan 1 2021 (Today and tonight) Satellite shows the center of the upper low over southeast Oklahoma, near Coalgate. The low is expected to continue moving north, then northeast away from our forecast area later today. On the northwest side of the low, snow is the dominant precipitation type, and some of it is rather heavy. Some light rain or freezing rain will be possible this morning in this general area before the precipitation ends later this morning.
Snow and freezing rain were falling across the area. The freezing rain is still expected to transition over to snow everywhere this afternoon. Saturday afternoon and evening: Upper low seen on Water Vapor movie loops over northern old Mexico tracks northeast into central MO and central IL on Saturday. Temperatures surface and aloft will certainly be below freezing thus the precipitation will be in the form of snow.
At the surface, the triple point low pressure was over southeast Illinois, where temps/dewpoints surged into the 50s. For our area, temps stayed in the 30s, and mostly in the lower 30s. Low stratus will linger overnight and there could be a freezing drizzle/drizzle threat from that, but low level cyclonic flow decreases especially after midnight.
The cooler NAM and ECM guidance is in place for lows in the teens and single digits. A weak cold front will work through western and north central Nebraska Saturday night.
543 PM CST Fri Jan 1 2021 A very amplified pattern continues to reside across North America at this time, highlighted by ridging on both coasts, and an anomalous trough over the central US. Within that trough, one winter storm system is departing the Central Plains, with another upper low spinning over northern Mexico. That second upper low will briefly open up and lift NE into the Southern Plains, before beginning to deepen again as it approaches the Mid MS Valley. Upper level forcing in conjunction with moisture transport in the lower levels of the atmosphere will, given this comes to fruition, bring another round of precipitation. Upper low that brought snow to the region is now moving into the Ohio Valley with another, much weaker, impulse tracking over southwest TX.
Mainly dry conditions are expected through Saturday with the exception of some patchy early morning freezing fog in some valley locations.
Quiet weather remains on track through Saturday night even as another upper low lift northeast across west-central Texas tonight. Deepening southwesterly flow ahead of this trough and modest isentropic upglide will transport a stratus layer north from the Rio Grande Valley through tonight, mainly affecting the Coastal Bend. This cloud layer is forecast to remain too thin for precipitation before it clears the coast Saturday morning with the upper trough axis. Surface ridging departs on Saturday night ahead of light southerly flow, yet dewpoints remain low enough for a third consecutive night of chilly lows. Any freezing temps should remain too localized for headlines.
Temperatures are expected to drop below freezing in these areas overnight, so freezing fog is a potential if visibilities drop low enough. Winds will shift from the southwest to the northwest overnight as a weak cold front moves across the state.
Guidance and the low level/near surface environment, for at least this evening, supports the continuance of the Dense Fog Advisory, so it has been expanded further south and east and extended in time to midnight CST tonight. It's entirely possible that fog and low clouds are continuing into Saturday morning, before better mixing and some low level waa can finally scour out the low level moisture, fog and clouds.
429 PM MST Fri Jan 1 2021 Skies were sunny or mostly sunny across much of the region early this afternoon as a positive tilt mid-level ridge moved over the northwest portion of the forecast area. Instability and residual moisture combined with weak lift associated with this disturbance appeared to be generating isolated light snow showers over the higher peaks of the San Juan Mountains according to cooling tops in infrared satellite imagery. In the wake of the trough showers are expected to diminish during the overnight hours.
533 PM CST Fri Jan 1 2021 Upper trough will move through the local area accompanied by passing clouds. Should note that MVFR ceilings could very well spoil the forecast as the upper trough moves through between 12z and 18z, however. After 18z, trough axis shoves remaining low level moisture east of the local area and VFR conditions should prevail. occluding low pressure has a center near Evansville Indiana with the upper low in southeast Missouri. The next in a parade of upper lows was over northern Mexico, with another approaching the Pacific Northwest coastline. Dew points range from the lower 40s northwest to mid 50s over lower Plaquemines Parish.
216 PM MST Fri Jan 1 2021 Afternoon GOES WV/IR imagery showed two upper lows, one over northern Mexico, and the second over eastern MO/western IL. The Midwest upper low continued to produce a wide swath of snow/ice. A large scale ridge was situated over the Intermountain West. The low/mid level gradients were more relaxed compared to 24 hours ago. Therefore, the High Wind Watch was upgraded to a Warning.
Afternoon GOES WV/IR imagery showed two upper lows, one over northern Mexico, and the second over eastern MO/western IL. The Midwest upper low continued to produce a wide swath of snow/ice. A large scale ridge was situated over the Intermountain West. The low/mid level gradients were more relaxed compared to 24 hours ago. Therefore, the High Wind Watch was upgraded to a Warning.
306 PM CST Fri Jan 1 2021 Main forecast challenge in the short term lies with another upper level low pressure system that will be ejecting northeast from TX/OK area on Saturday. Thermal profiles do hint at the possibility of a touch of light snow over portions of sw IL/se MO, closer to the upper low, with possibly light rain or rain/snow mix farther southeast.
Very low PWAT values are associated with the trough, so no precipitation is expected (outside of some flurries over the eastern San Juan Mountains). The main impact for tomorrow will be gap flow winds forming over the lower Arkansas River Valley and the greater Spanish Peaks region.
Most valley locations today will become warmer than normal on the heels of a warm front that passed through the Northern Rockies this morning. Precipitation will take a break this afternoon under a very short-lived period of high pressure. Meanwhile, a low pressure system spins off the coast of British Columbia. Later this afternoon or this evening, a weak cold front associated with the Pacific low pressure system will swing across the Pacific Northwest.
/issued 227 PM CST Fri Jan 1 2021/ SHORT TERM (Now through Saturday Night): High pressure will continue to build across Deep South Texas in the short term with dry and cool conditions.