Aikyam-Lab/Synoptic-Bench huggingface dataset:
In the wake of the frnt, gusty N to N/Wrly winds wl follow and usher in drier and cooler air. December again, as cold air funnels into the region overnight, w/ temps bottoming out in the upper 20s over far Nrn AR Sun morning, and readings hovering around or just above the freezing mark in Cntrl and Srn AR. As high pressure begins to settle over the region and the sfc pres grad relaxes, winds should follow suit and settle out Sun afternoon.
It was somewhat unclear what was driving the lower visibilities west of Tupelo, surrounding visibilities over north MS and northwest AL prevailed at 6 to 10 miles. The nearest surface theta-e gradient/marine warm front was apparent 80 to 100 to the south, over central MS. Dense fog potential should ease with the eventual southward push of the cold front after 3 AM CST / 09Z. The main trough, currently over the Four Corners Region, will swing eastward overnight and help push the warm front back south as a cold front Saturday morning.
This afternoon, clouds begun to overspread the area while temperatures ranged from the mid 30s to the low 40s across the area. North of the area, high pressure was sliding in across the Great Lakes. A warm front was located down in Arkansas. Winds were out of the east and helped to keep the low levels somewhat drier. Warm front will lift north towards area as a wave moves through with the majority of the precip south of the area. GFS and CAMs eventually saturate the low levels. Fortunately, we will warm above freezing in the morning leading to an improvement of any icy conditions.
Expect temps to hold steady or even rise a few more degrees this morning, before the sfc wave lifts quickly into the Upper Ohio Valley and opens the door for the cold front and its associated rain shield. Rain will shut off from NW-SE this evening as high pressure builds from the Upper Midwest. Sunday morning mins either side of freezing are actually slightly above normal for mid-December. By Sunday morning, the cold front should be east of KY as dry air advects in from the west and scours out the clouds by afternoon.
1129 PM CST Fri Dec 17 2021 Biggest forecast issues include passing of a cold front this late afternoon/evening, bringing brisk conditions tonight/Saturday morning, also near-critical fire wx for part of the CWA Sunday.
Poor flight conditions expected to continue through the next 24 hours ahead of a cold front. MVFR CIGS will prevail at all sites today as a cold front makes its way across the Tennessee Valley. Diegan Chattanooga Airport, TN 69 44 51 33 54 / 90 80 0 0 0 Knoxville McGhee Tyson Airport, TN 68 42 48 29 53 / 80 90 10 0 0 Oak Ridge, TN 67 40 47 29 51 / 90 90 10 0 0 Tri Cities Airport, TN 65 39 44 23 50 / 90 90 20 0 0.
Our second round of showers will come along the cold front expected to move through later today.
1104 PM CST Fri Dec 17 2021 Did boost pops over parts of our area mainly north of of I90/north central WI and included pops farther south with the trough pushing into MN tonight and across the forecast area. GOES water vapor imagery shows a broad trough across the northern Rockies and high plains early this afternoon. Lift associated with the approaching trough will increase this evening and tonight. However, much of the lift will go into gradually saturating the low to mid-levels. The highest chances for light snow still remain across north-central WI late tonight into Saturday morning with not much more than perhaps some flurries farther south. High pressure will slowly build east into the area on Saturday with modest cold advection through the day limiting highs to the 20s to low 30s. ridge axis builds into the Upper Midwest.
Cooler through Sunday night, then trending increasingly above normal. Rain will continue to exit the area early this morning as a cold front moves through. Clouds will linger across much of the area today as an upper trough moves into the area. Highs today and Sunday will be in the low to mid 40s while lows tonight and Sunday night will be in the upper teens to mid 20s. 1" of rain in any 24 hour period, the highest values through the end of the month are generally around 20%.
245 AM EST Sat Dec 18 2021 Surface analysis shows high pressure centered offshore over the subtropical Atlantic Ocean, with a ridge extending westward along the northern Gulf Coast, and a stationary front draped from the Mid Atlantic coast westward through the Southern Plains. A surface front will slowly advance across Texas and the Ark-LA-TEX region before arriving near the Lower Mississippi Valley and the Gulf Coast States late tonight into Sunday morning. As for the Keys, high pressure will gradually slide east and away from the Florida Peninsula ahead of the the surface front mentioned above.
1033 PM MST Fri Dec 17 2021 Current surface analysis shows cold front has pushed just south and east of the forecast area, with breezy to windy conditions and colder air pushing in. Upper level analysis shows trough moving east through the northern high Plains. The gusty winds and snow showers will taper off late today and this evening as the trough moves east of the region and high pressure settles over the Dakotas. Warmer air will start to return to the area on Saturday as the Canadian high shifts east of the region. The next cold front will arrive late Sunday and Sunday night, bringing below average temperatures back for the early part of the week.
Now that the upper trof out west is pushing this way, we see progression with the convection that should preclude any flooding concerns. a cold front will push south and east of the region, with strong high pressure building in.
223 AM CST Sat Dec 18 2021 An upper trough stretching from the northern plains into the desert southwest was moving east per the 08Z water vapor imagery while another upper wave approached the AK panhandle and British Columbia. Surface observations showed a cold front from the Ozarks into central TX with high pressure centered over eastern MT and pressure rises through the central plains. Meanwhile southerly winds and sunshine are expected to cause warmer temperatures with lower RH values.
The main cold front has now entered northeast Oklahoma and will surge southeast overnight, taking the showers and thunderstorms with it.
At 20Z, regional mid-level water vapor imagery showed a trough over the Rockies with southwest flow over the eastern Kansas. That ridge will build southward from the Intermountain West into the Plains tomorrow (Saturday), bringing a cooler air mass with it. Winds will shift back to a southerly direction on Sunday while that ridge pushes east of the area.
Warm front has moved northward to the Kentucky border per surface obs, with temperatures south of the boundary now in the low 60s with dewpoints in the upper 50s to low 60s. CAMs show a slug of showers and a few thunderstorms spreading northward over our southeast half late tonight through Sunday morning, while showers increase from the northwest through the day as the cold front progresses southeastward across Middle Tennessee. Pops will also increase from the northwest through the day as the cold front progresses southeastward. South winds with isold SHRA are expected overnight through Saturday morning with a warm front north of Tn. Winds will shift to NW Saturday afternoon and coverage of SHRA will increase with passage of a cold front.
With a warm front lifting through Saturday night, temperatures will rise during the overnight hours with Sunday's highs mostly occurring during the morning hours. Concerned that forecast highs for Sunday are too high because of anticipated cold frontal passage during the day, but either way it'll be colder late Sunday afternoon.
The loss of DGZ saturation by mid morning and a cloud layer mostly warmer than -10 C may turn the precip type over to light freezing drizzle or snow grains.
This ridge will continue to move eastward tonight, shifting northwest winds to become southwesterly.
A shakeup occurs after 12Z Saturday as a cold front moves across south-central Texas from north to south.
A strong cold front will sweep into the region Saturday evening, bringing another round of widespread showers and a few thunderstorms to the area (thanks to a modest ribbon of elevated instability). These clouds and the breezy NW winds will make for a much cooler day as highs will struggle to top the 50 degree mark.
1004 PM CST Fri Dec 17 2021 Did boost pops over parts of our area mainly north of of I90/north central WI and included pops farther south with the trough pushing into MN tonight and across the forecast area. GOES water vapor imagery shows a broad trough across the northern Rockies and high plains early this afternoon. Lift associated with the approaching trough will increase this evening and tonight. However, much of the lift will go into gradually saturating the low to mid-levels. The highest chances for light snow still remain across north-central WI late tonight into Saturday morning with not much more than perhaps some flurries farther south. High pressure will slowly build east into the area on Saturday with modest cold advection through the day limiting highs to the 20s to low 30s. ridge axis builds into the Upper Midwest.
While low cloud cover is likely to linger under a stout midlevel inversion throughout the day, measurable precipitation should largely come to an end across the area by early afternoon as the low moves through and the front begins to sweep eastward. While there is some substantial and strengthening subsidence above the inversion, the lapse rates, trapped low level moisture, and hints of weak UVV in the lowest levels suggest some patchy drizzle can be expected. The remainder of the short term looks dry and quiet, if a little cool, as high pressure overspreads the area.
Discussion It is going to be a rather chilly Saturday, with high pressure and a polar airmass moving in from the north.
Flow finally starts to shift from northwest to more westerly as a ridge starts to build in Sunday morning. In accordance with previous discussions much of the medium range forecast period will be dominated by a low amplitude ridge over the western U.
Relatively quiet short term forecast with a weak cold front that is pushing through during the overnight hours. Winds have turned more northwest to northerly 10-20 mph and remain so throughout the day Saturday before turning southerly in the evening as high pressure builds back across the CWA. Morning low temperatures Saturday will drop into the teens and low 20s northwest to southeast in wake of the aforementioned cold front with afternoon highs struggling through the 30s for much of the CWA minus southern counties along the Oklahoma state line that should see the 40 degree mark.
A transitory ridge will build over the Cowboy State today. Temperatures will be slightly warmer in a few areas, but still slightly colder than normal. Otherwise, isolated snow showers will be possible over far northwestern portions as a Canadian cold front slowly approaches.
The coldest air aloft with the upper- trough will move overhead today, leading to high temperatures of 10 to 20 degrees across the CWA (around 10 degrees below normal). Low temps should remain fairly cold Saturday night, but the forecast is tricky considering fresh snow pack and mostly clear skies, but at least some high clouds and increasing WAA on southerly winds thanks to incoming low pressure. Given increasing south-southwesterly winds as this system approaches and the fresh snow pack, there's a window of opportunity for some blowing snow Sunday morning across the higher elevations and downslope regions of the Prairie Coteau. Sunday should be considerably warmer than Saturday, warm enough to limit blowing snow by the afternoon (which is also when winds lessen). This warmth will be short-lived though, as a cold front enters the CWA by 00z Mon.
High pressure will continue to build to the east through tonight. A cold front approaches from the northwest Sunday morning and will move southeast across the area on Sunday.
Our cold front has moved through our entire forecast area as it will continue to push across far southeast Oklahoma and northern Texas. One remote thing to keep an eye on for early Sunday morning would be development of freezing fog across southeast Oklahoma.
This will help lead to slightly warmer minimum temperatures (perhaps even above normal in some of the high elevations) across a good chunk of the forecast area tonight. The ridge aloft still looks to be the main feature through the first half of the week. Meanwhile, an anamolous low pressure will stall off the coast of the Pacific Northwest. Persistent southwest flow and a strong trough will allow this system to tap into deep Pacific moisture.
An upper level trough is passing through this morning from west to east, bringing light snow to much of the region. As the trough passes to the east this morning, expect winds to become northwesterly and push the band of lake-effect snow over the Bayfield Peninsula. A brief period of high pressure will pass through tonight with a clipper system passing just north of the Canadian border Sunday and Sunday night.
(Today and tonight) Early this morning, a cold front was working its way south across the area. Latest guidance shows a slightly warmer temperature profile, which would support just some light rain through the mid morning hours. Temperatures will be much colder tonight and will range from the upper 20s across the Big Country where less cloud cover will exist, to the lower 30s elsewhere.
Dense fog across NE AR and the Mo Bootheel is finally mixing out ahead of the approaching cold front. Temps are mild across the Mid-South for mid December with readings mainly in the lower to mid 60s with some 50s across NE AR and the MO Bootheel where the warm front stalled overnight. Showers are lined up ahead of the developing cold front that is located roughly along the I-44 corridor in Missouri. The cold front will push across the Mid-South today with showers pushing SE during the day. As the cold front plows SE brisk N winds will develop and temps will fall in the 40s. Since the front will not reach NE MS until later temps will reach into the lower to mid 70s there today.
Upper trough will swing across the region today, though really dry air in place will limit any precip development. Some pockets of low stratus in place around the Palmer Divide early this morning, but steady westerlies in place will help continue eroding this low level moisture and with sunny/clear skies to be in place.
355 AM PST Sat Dec 18 2021 Weakening offshore flow under high pressure aloft will make for fair, mild days, and chilly nights this weekend.
649 AM EST Sat Dec 18 2021 Rain will continue as a low pressure system crosses the area today. High pressure, dry conditions, and seasonable temperatures return Sunday. A low pressure system tracks northeast across the forecast area today, continuing the rain until this evening. In the warm sector to the southeast, temperatures warm to the low 60s while the northwest will see little change in temperatures, only warming to near 40. With the passage of the cold front late this afternoon, temperatures begin dropping and we could see some gusts of 20-25mph across the area. Any lingering rain in the southeast will clear out tonight with the passage of the cold front. With northerly flow and cold air advection on Sunday, can expect a low around freezing in the morning before warming slightly to the mid- upper 30s during the day.
Outside of major urban areas, near freezing temperatures are expected in the San Joaquin Valley tonight and Sunday night.
A rapid warmup into the middle to upper 20s is expected through Sunday afternoon as a warm front lifts northward. The warmup and light snow will be short-lived as a cold front approaches the area late Sunday evening.
Otherwise, weak northwest flow aloft will keep temperatures in the low to mid 40s across the plains. In the high country, gradual 700mb warm air advection will rebound temperatures from below zero this morning into the 20s to low 30s. An upper level ridge will slowly build through the day with very dry air below. Cross- sections show almost no low or mid-level moisture, and the only a few clouds are expected this afternoon over the high country. High pressure will continue to build tonight with clear skies across the forecast area. Overnight lows should be a little warmer than this morning's as weak warm air advection continues. Ridge of high pressure builds across the region through this weekend with a moderate west to northwest flow.
Several bouts of bkn to ovc cloud decks will develop and slowly shift south throughout the day as the main H500 positive tilted trough well upstream over northern Baja slowly moves to the east assisting in mid level moisture transport.
The low clouds will float around for a while this morning until warmer temperatures dissipate it. Upper ridge moves through the area today and tonight which will bring warmer temperatures. A warm front lifting NE through the area tonight will allow temperatures to rise during the overnight hours.
Otherwise a cooler and drier continental airmass will spread over the region today, with high temps closer to or even below normal, along with breezy north winds making it feel almost like December, which we haven't seen much of this month.
As the high pressure system moves through, the winds will diminish a little, but will still be a little breezy. Lows tonight will be mainly in the lower teens. The lowest relative humidity will be in the west and southern parts of the forecast area. Another weak upper level wave and cold front are expected to move through the forecast area Sunday night.
317 AM MST Sat Dec 18 2021 Upper air analysis shows weak ridging building into much of the western CONUS, including the Northern Plains. Surface Canadian high pressure is pushing into the Dakotas, with mostly clear skies and winds becoming light. Surface ridging will push eastward this afternoon. A cold front will push through Sunday night, as a low pressure system moves eastward just north of the US/Canadian border.
A cold front will pass through the area Sunday night.
cooler temperatures are expected today behind a cold front that moved through earlier this morning. High temperatures are expected to be in the lower 30s to around 40. a broad upper level ridge moves over the area from the west. 850mb temperatures rise about 18F to 27F compared to Saturday supporting the better performing guidance over the past 7 days with afternoon temperatures in the lower 50s to lower 60s.
410 AM EST Sat Dec 18 2021 Rain will continue as a low pressure system crosses the area today. High pressure, dry conditions, and seasonable temperatures return Sunday. A low pressure system tracks northeast across the forecast area today, continuing the rain until this evening. In the warm sector to the southeast, temperatures warm to the low 60s while the northwest will see little change in temperatures, only warming to near 40. With the passage of the cold front late this afternoon, temperatures begin dropping and we could see some gusts of 20-25mph across the area. Any lingering rain in the southeast will clear out tonight with the passage of the cold front. With northerly flow and cold air advection on Sunday, can expect a low around freezing in the morning before warming slightly to the mid- upper 30s during the day.
337 AM MST Sat Dec 18 2021 Upper air analysis shows weak ridging building into much of the western CONUS, including the Northern Plains. Surface Canadian high pressure is pushing into the Dakotas, with mostly clear skies and winds becoming light. Surface ridging will push eastward this afternoon. A cold front will push through Sunday night, as a low pressure system moves eastward just north of the US/Canadian border.
An upper trough stretching from the northern plains into the desert southwest was moving east per the 08Z water vapor imagery while another upper wave approached the AK panhandle and British Columbia. Surface observations showed a cold front from the Ozarks into central TX with high pressure centered over eastern MT and pressure rises through the central plains. The latest RAP and NAM seem to have a good handle on the low CIGS, and will use them and a linear extrapolation for timing the CIGS at the terminals. Continued dry air advection should limit the time of lower CIGS and VFR conditions should prevail once the low clouds move/scatter out by the early afternoon. Meanwhile southerly winds and sunshine are expected to cause warmer temperatures with lower RH values.
Canadian high pressure approaching from the northwest will support much cooler temperatures and breezy northwest winds today. High pressure settling overhead tonight along with slackening winds and clear skies will support a rather chilly night, with forecast lows mostly in the teens. Temperatures will warm some into the 40s Sunday, although breezy south winds will support much cooler wind chills.
Weakening high pressure will result in SE/SSE winds today of around 10KT.
601 AM CST Sat Dec 18 2021 (Today and tonight) Early this morning, a cold front was working its way south across the area. Latest guidance shows a slightly warmer temperature profile, which would support just some light rain through the mid morning hours. Temperatures will be much colder tonight and will range from the upper 20s across the Big Country where less cloud cover will exist, to the lower 30s elsewhere.
Clouds have been slow to dissipate this afternoon but are now finally beginning to erode from the west as the low level ridge axis finally shifts east. On Sunday the ridge axis shifts east with southwest winds forecast to increase to around 15 mph with gusts of 25 to 30 expected.
943 AM PST Sat Dec 18 2021 Weakening offshore flow under high pressure aloft will make for fair, mild days, and chilly nights this weekend.
236 PM CST Sat Dec 18 2021 Tonight into Sunday, an upper-level trough will advance east of the Midwest, promoting large-scale subsidence as mid-level heights rise in its wake. This evolution will cause a surface pressure ridge to shift into the CWA Sunday morning with winds becoming light as the attendant pressure gradient relaxes. Although some areas of stratus may linger overnight/Sunday morning and limit fog development below, confidence was high enough near the ridge axis to include mention of fog across northeastern MO and west-central/south-central IL Sunday morning.
Mild temperatures in the lower to mid 60s will rise a few more degrees and approach 70 in a few spots. A cold front moves during the evening hours with showers continuing behind the front into Sunday morning. MFR conditions will linger through the last 6 hours of the TAF period behind cold front with low ceilings.
This trend should continue as mid level short wave trough continues east and while some flurries may linger into the afternoon over our east, most locations should see an end to this. A rapid warmup into the middle to upper 20s is expected through Sunday afternoon as a warm front lifts northward. The warmup and light snow will be short-lived as a cold front approaches the area late Sunday evening.
However, warmer conditions are expected through the new week. High pressure will drop into the area by tomorrow morning with dry conditions. Dry weather is expected through most of the period despite a cold front moving through the state middle of the week.
As a warm front lifts up through the region this evening and tonight, temperatures will go up.
200 PM CST Sat Dec 18 2021 A strong cold front is pushing through Middle Tennessee at this moment, with temperatures turning sharply cooler behind the boundary. Obviously, tomorrow will be considerably colder than today, and this will help usher in a largely rain-free week across Middle Tennessee as temperatures moderate close to seasonal normals before trending warmer as we get close to Christmas.