Aikyam-Lab/Synoptic-Bench huggingface dataset:
An upper ridge continues to progress eastward through the day. Areas with the lowest RH values will not coincide with areas with the strongest winds. Tuesday morning, an upper trough will move over the Bighorns before pushing into eastern Colorado. A cold front is expected to move through the region from the north during the morning hours with winds shifting to the north in the afternoon. High temperatures will be much cooler, ranging from the low 40s in Eastern Colorado to the low 50s across the eastern part of the CWA. Dry conditions will persist despite the front and trough in the region.
Our forecast area remains located along the base of a deep upper level trough that extends southward across the Great Lakes and Mid-Mississippi/Tennessee Valley regions early this afternoon. The low cloud cover should continue to decrease over most of our area through the afternoon, except perhaps holding on a little longer over interior parts of south central Alabama, along and northeast of a Camden to Andalusia line, where moisture persists a little longer along the pivoting trough axis. Lows are still forecast to range from 25-30 across locations especially along and north of Interstate 10, and in the lower 30s along the immediate coast. The only places that may stay above freezing are along the barrier islands, where winds remain elevated. Highs Tuesday remain well below normal in the lower to mid 50s.
1132 AM CST Mon Nov 30 2020 The upper trough that moved over the region overnight will strengthen into a closed low system as it moves northeastward over across the eastern CONUS. Weak ridging will be building over the Plains today and tomorrow bringing seasonable temps and dry conditions for the next couple of days. The next wave comes out of the Pacific Northwest and tracks across the Colorado Rockies, with the trough axis progged to be over the western Plains by tomorrow night.
We'll have Round 1 that's currently ongoing and then we should see an additional bout of snow across the Plateau this evening as a second lobe of energy wraps around the west side of the upper low. Freezing temperatures are expected overnight and as long as the precipitation shuts off early enough, the winds will likely do their job of drying out roads. If the winds start dying off too early though, we will need to keep in mind there could be some icy spots tomorrow morning, especially on bridges and overpasses.
Behind the cold front, low level CAA may suggest some saturation within the lowest 1 km.
Aside from a shallow surface layer, the thermal profile is subfreezing with steep lapse rates. The cold front which was in the region last night is now moving across north Mississippi.
200 PM CST Mon Nov 30 2020 (Issued 200 PM CST Mon Nov 30 2020) Tonight through Tuesday night: Combo of low level thermal trough and broadly cyclonic flow keeping cloud cover in place. Surface and mid level ridging tries to gradually work in here through Tuesday night but suggestion in progs is that it makes only our western cwa by later Tuesday night.
Clear skies and warming temperatures expected today ahead of the upper trof. 3am discussion: Upper ridge will move through Eastern Montana today with warm temperatures and mostly clear skies. The ridge moves to the east this evening and an upper trough/low moves into the region tonight with a cold front. There will be enough moisture with this system late tonight and Tuesday for a chance of light snow/light rain/light freezing rain depending on temperatures. An upper low drifts south along the MT/Dakota border Tuesday Night which will give the east a chance of light snow.
355 PM EST Mon Nov 30 2020 Water vapor imagery highlights a potent long-wave trough across the eastern United States, maintaining a powerful surface cyclone moving northeast through the northern Appalachians. The cold front associated with this system is nearly on our doorstep, and will press into the Dry Tortugas in the next hour or so. Warm air advection and pre-frontal troughiness has been across the Keys most of the day, with extensive cloud cover, patches of stratiform rains, and a few discrete showers. By midnight tonight, northwest to north breezes will freshen appreciably across the island chain, driving cooler and drier air through the Keys.
Morning lows have stayed in the lower 20s in western North Dakota where winds are just strong enough to keep temperatures from bottoming out, whereas some locations in the central part of the state are in the mid single digits.
Clouds covered most of IL while high pressure building in from the west was providing sunny skies over most of Iowa west of a line from Dubuque to Fairfield. High pressure building over the area will result in light northwest winds and clear skies overnight and through the day Tuesday.
1119 AM CST Mon Nov 30 2020 Stratus across eastern Minnesota and Wisconsin will erode from west to east this morning as a trough axis shifts east. Southeast flow will begin across western Minnesota late as the ridge axis slides slightly to the east, allowing for a little milder temperatures there. We should start to see some warmer temperatures late this week into the weekend as westerly winds advect some warmer air into the region. Warmer, now that we will be in early December, is upper 30s into low 40s for high temperatures.
A cold front was moving through the forecast area this morning also. The main upper trough will deepen over the southeast through tonight. Snow accumulations should be around an inch or less except locally higher amounts in the higher elevations and on west and northwest facing slopes. Temperatures should be falling during the day and overnight lows will range below freezing area wide. The one thing to mention though is the GFS has been the most consistent with this system showing a single low pressure center that weakens as it moves east.
Still fairly certain that the bulk of accumulations will be east of I-65 this afternoon and tonight as another lobe of energy rotates around the backside of this upper trough. Not going to make any adjustments to current snow totals, which means we're still expecting 1-2 inches in the advisory area with spots of 3 inches in some of the higher elevations.
Temperatures will gradually warm today and tomorrow as ridging builds over the area. The ridge will be sandwiched between two low pressure systems.
Skies should clear out this evening as high pressure returns to the area. Clouds have been tough to scour out this afternoon, as a deep upper trough axis over Illinois drifts slowly toward the Indiana border. The high res models are having a tough time resolving the coverage and timing of the low clouds/flurries clearing, causing low confidence on when we will be able to finally get them to shift east of Illinois. Temps may remain a bit warmer in our eastern counties as a result of later clearing. Plenty of sunshine is on tap for Tuesday, along with lighter winds under surface ridging.
Also beginning to get reports of snow across portions of Middle Tennessee and the Cumberland Plateau where temperatures are in the low to mid 30's. A deep upper level trough will continue to dig into the Tennessee Valley. Diegan Chattanooga Airport, TN 27 43 25 51 30 / 20 0 0 0 10 Knoxville McGhee Tyson Airport, TN 28 38 23 49 27 / 50 10 0 0 0 Oak Ridge, TN 28 39 24 49 27 / 40 0 0 0 0 Tri Cities Airport, TN 29 35 20 45 24 / 70 20 0 0 0 TN.
1151 AM EST Mon Nov 30 2020 A vigorous cold front has pushed through Punta Gorda and Buoy 42023, with winds shifting sharply to the northwest and increasing to near 20 knots. A developing low pressure system along the northern Gulf coast will move northeastward this afternoon. A trailing cold front will sweep quickly southeastward across the Gulf of Mexico, and reach Florida Keys coastal waters this evening. Behind the cold front, strong northerly breezes will follow into Tuesday morning.
Benign weather across the forecast area today as the region resides under the subsident side of a deep trough digging into the eastern conus. Current forecast has lows in the mid to upper teens, but would not be surprised to see some favorable locations such as the Nish River Valley and other low lying areas drop a few degrees cooler.
Fairly benign weather pattern for the short term forecast under the influence of upper level ridging across the Rockies and northwest flow aloft for the high plains with weak leeside troughing over eastern Colorado. Afternoon high temperatures will push into the low to upper 50s, with warmer readings towards the Colorado state line due to more of a downsloping effect. Not quite as cold as Monday morning due to the more downsloping low level flow out of the southwest but expect a cold frontal passage late Tuesday morning. North winds will gust up to the 30-40 mph range during the afternoon hours with increasing clouds into the evening as an upper level low pushes closer to the high plains from the northwest.
Low dwpnts in the single digits and mostly clear skies will favor below normal temps Tue AM, freezing temps in most areas. Assocd surface winds will be a little on the breezy side at times during the day, but will increase in the evening with the passage of the cold front, initially 20-30 mph post-frontal across the plains. Cold wx will hold into Fri, but a few degrees warmer than Thur. Models struggle to resolve the mid/upper level low, but it should be a little warmer Sat/Sun. Precip is possible Mon AM when the ECMWF lifts out the mid/upper low.
surface cold front moving into eastern Washington and Oregon State.
There is abundant sunshine across the area in the wake of the upper low, but still cold temperatures with readings only in the mid 30s to low 40s early this afternoon. We have readings dipping down into the teens over a part of south central and central MO and into the low to mid 20s elsewhere. Some upper ridging builds into the area on Tuesday and should see low level winds become more southerly as well.
1113 AM CST Mon Nov 30 2020 A thermal ridge will develop across wrn Nebraska today and move overhead through ncntl Nebraska tonight. The temperature forecast today leans on the warmer deeper mixed GFS guidance for highs in the 40s and 50s. Teens are in place in the valleys where drainage winds will support cooler lows. A strong cold front, currently across nrn Canada, will sweep through wrn and ncntl Nebraska Tuesday. The cooler short term model blend plus bias correction was the basis for highs in the lower 40s Tuesday.
1058 AM CST Mon Nov 30 2020 Steady northwest surface flow has kept cooler air feeding into the area, resulting in a 20 degree drop from 24 hours ago. Given the 10- 15 mph winds and the lower 20 degree temperatures, wind chills this AM are widespread in the lower to middle teens, making for a rather unpleasant morning. The focus then shifts to the mid to late week slow moving mid level trough, which until recent model runs appeared to move through wind minimal consequence.
Winds were light out of the south on the western side of this ridge across western Minnesota. However the upper level pattern will favor lee-side warming across the High Plains, and this modified warm air mass will keep temperatures above the seasonal average for early December.
12Z model data shows the low pivoting westward after 00z. However, as nightfall arrives and temperatures fall below freezing, some slick spots will probably develop.
333 PM CST Mon Nov 30 2020 A deep upper level trough continues to tranlate east of the of the area slowly dragging the colder airmass at the surface with it as it maintains a positive tilt aspect. The light southerly breeze should help temperatures overnight bottom around the low 20s.
Northwesterly H500 flow ahead of our next low pressure system moving into the central Plains for mid week will continue large scale upper level subsidence over the Panhandles. The main feature will be the cold front that moves south into the Panhandles during the second half of the day tomorrow.
01/00Z TAF CYCLE VFR conds wl prevail thru the PD as high pressure prevails. High pressure will continue to dominate the Arkansas weather Tuesday and Tuesday night. Highs on Tuesday will be in the lower to mid 50s.
A deep upper level trough continues to tranlate east of the of the area slowly dragging the colder airmass at the surface with it as it maintains a positive tilt aspect. The light southerly breeze should help temperatures overnight bottom around the low 20s.
720 PM EST Mon Nov 30 2020 The cold front that moved across the Florida west central and southwest Florida has pushed well south of the forecast area. Canadian high pressure is building over the region in the wake of the front with colder drier air advecting across the area. and the lower to mid 60s south.
1-3 inches for the northern and central mountains, with up to 4 inches at the highest elevations, and less than an inch in the mountain valleys.
238 PM PST Mon Nov 30 2020 A dry cold front will move through northeast California and western Nevada this evening and tonight. It will be cooler Tuesday, but still seasonable daytime temperatures. A dry cold front is pushing through the area today, with winds gusting around 30-40 mph for areas north of Susanville into the Surprise Valley and northern Washoe County. Breeziness mixing down into the lower valleys and foothills along the Sierra Front and Mono/Mineral. As of this writing, our temperature has jumped into the low 60s and inversion layer has mixed out of the Truckee Meadows.
A cold front will sweep south across the terminals late Tuesday afternoon with winds quickly veering from southwesterly to northerly as the front passes close to the end of the forecast period.
A North Pacific Trough trough passes quickly across The Treasure State. A tight height gradient favors strong gusty west-southwesterly winds ahead of the trough. As the trough exits rapidly to the southeast, accumulating snow ends across the region around noon, with some lingering snowfall continuing over The Little Belt Mountains and some of the mountains of the southwest into the afternoon hours.
Little change in overnight temperatures is also expected as the dry airmass remains in place and many San Joaquin Valley locations drop below the freezing mark during the early morning hours. With the areas of freezing temperatures in the San Joaquin Valley during the next couple of mornings, the Freeze Warning remains in effect there. There are model differences with the exact evolution of the synoptic pattern, but there is general agreement that we will end up with a low pressure system to our south for the end of the week into early next wek.
626 PM CST Mon Nov 30 2020 A major downstream eastern CONUS upper low will block most of the western energy from moving very far east over the next few days, shunting the energy into the southwest US. The result should be air piling up into a narrow negatively tilted upper ridge over the Northern Rockies into Montana. This upper ridge will eventually flop over into the Northern Plains by the end of the week as teh southwest upper low slides slowly east. While the southwest US gets the cool upper low, the Northern Plains region will continue to be above normal and generally dry, with just a brief shot of some light snow Tuesday night west. For now we will continue to monitor the low temperatures tonight, and see if we need to lower them later.
316 PM CST Mon Nov 30 2020 A potent upper-level trough brought occasional flurries to the Mid-South but will continue to pull off to the east overnight.
Snow continues to expand into the Northern Rockies as a cold front and upper low pressure system moves through the region. Mountain passes will have the highest impacts from snow and low visibility but valleys will also see periods of snow and the potential for slick roadways through this evening. Showers are expected to decrease overnight at the trough moves to the east. Showers may linger along the Divide on Tuesday, otherwise high pressure will begin to build.
High pressure begins to slide east tomorrow morning and into the afternoon, resulting in return flow and winds becoming re-established at a more south to southeasterly direction. Dry air associated with the high pressure will result in VFR conditions through the TAF period. /issued 358 PM CST Mon Nov 30 2020/ Despite plenty of sunshine this afternoon, temperatures have remained in the low to mid 50s thanks to brisk cold air advection in the wake of yesterday's cold front. Lows along the I-10 corridor have been much more consistent with temperatures touching or just below freezing for four or so hours early tomorrow morning.
Nearly all of our CWA will have freezing temperatures Tuesday morning and we have issued a Freeze Warning for the entire area. Temperatures will drop below freezing starting across the northern counties late this evening with all area below freezing by around 4 am. Temperatures will warm quickly after sunrise with most places back above freezing by around 9 am. The high center will continue eastward Tuesday and the winds across our CWA will become southerly to southeasterly. This will bring warmer, moister air back to the region. High temperatures Tuesday will be a few degrees warmer than today.
This Evening Through Monday Upper ridge overhead will move east as an upper low crosses the northern US. Light snow showers are possible over northeastern WY and the northern Black Hills after midnight through Wed morning, with some snow showers possible over southwestern SD Tues night- Wed morning as the upper low deepens over the central Plains. A cold front will cross the area after midnight tonight, bringing strong northwest winds to the area during the day Tue. Upper ridge builds after low moves away, with warm and dry conditions returning toward the end of the week. A cold front will cross the area this evening into tonight, bringing strong NW winds late tonight through tomorrow.
Beneath a dynamic upper-level low pressure system, enough lift in the cooling lower layers is just enough for some light precip (in this case flurries) to be generated. As we approach the weekend, forecast confidence drops some concerning a weakening trough that is expected to push east across the MS Valley region.
This Evening Through Monday Upper ridge overhead will move east as an upper low crosses the northern US. Light snow showers are possible over northeastern WY and the northern Black Hills after midnight through Wed morning, with some snow showers possible over southwestern SD Tues night- Wed morning as the upper low deepens over the central Plains. A cold front will cross the area after midnight tonight, bringing strong northwest winds to the area during the day Tue. Upper ridge builds after low moves away, with warm and dry conditions returning toward the end of the week.
Winds for most of the region continue to be breezy as a cold front works its way through the state tonight. Fair, dry weather follows the cold front, and helps to keep afternoon highs above normal with overnight lows closer to normal.
Temperatures were in the lower to mid 30s, with the coldest temps in our western counties (and higher elevations), and mildest east (and valleys). The precip was in the form of snow where temperatures were near freezing, but rain was still mixed in at the warmer locations. Combined with loss of our limited insolation, surface temps will fall below freezing from west to east and top-down as we move through the evening.
/issued 316 PM CST Mon Nov 30 2020/ A potent upper-level trough brought occasional flurries to the Mid-South but will continue to pull off to the east overnight.
High pressure will keep clear skies much of this week with light offshore winds at time.
Wendesday should be much closer normal, but cooler than we have been, with highs in the 30s.
A shallow cold front will translate across the area tonight into early Tuesday.
/issued 720 PM EST Mon Nov 30 2020/ The cold front that moved across the Florida west central and southwest Florida has pushed well south of the forecast area. Canadian high pressure is building over the region in the wake of the front with colder drier air advecting across the area. and the lower to mid 60s south.
320 PM CST Mon Nov 30 2020 The back end of the deformation zone and trough will move through the WFO PAH forecast area this evening. A sharp reduction in the surface pressure gradient will occur as the high amplitude ridge moves in overnight. Although the winds will diminish overnight, the lowest wind chills will still occur in the pre-dawn time frame coincident with the overnight lows.
North winds will increase again Tuesday leading to gusty winds in the Colorado River Valley as a low pressure system dives south from Canada to the Four Corners Region. North breezes and slightly lower temperatures will likely hold the second half of the week as the low pressure system circulates around the southwest states.
An upper level trough over the Northern Rockies will dive southeast tonight and track across the Central Rockies. A cold front associated with this system will push south across the state Tuesday morning. For the lower elevation, snowfall is expected to be short lived and less than an inch. There still will be enough moisture across the higher elevations for continued light snow showers through the night, with only a few isolated snow showers expected over the plains. Only minor accumulations are expected with up to an inch or two on the higher peaks and less than half an inch for the plains.
Winds will become light and variable overnight as high pressure settles over the region.
As the upper trough pivots across the region late this evening, deep lifting for precipitation production will advect east/northeast, leaving only orographically forced precipitation behind. As for the high terrain, still awaiting those reports which likely won't come until the morning with the Mt Leconte and Newfound Gap observations. However, given persistent returns on radar, would expect significant accumulations across the higher elevations. CDG Chattanooga Airport, TN 27 42 25 51 30 / 40 10 0 0 10 Knoxville McGhee Tyson Airport, TN 27 38 23 49 27 / 80 10 0 0 0 Oak Ridge, TN 26 38 23 49 27 / 60 10 0 0 0 Tri Cities Airport, TN 26 33 19 45 24 / 70 20 0 0 0 NC.
358 PM CST Mon Nov 30 2020 Despite plenty of sunshine this afternoon, temperatures have remained in the low to mid 50s thanks to brisk cold air advection in the wake of yesterday's cold front. Lows along the I-10 corridor have been much more consistent with temperatures touching or just below freezing for four or so hours early tomorrow morning.
Some showers linger this afternoon, especially in the Cascades, as an upper trough moves through. High pressure begins to build quickly over the Pacific Northwest on Tuesday, setting the stage for a shift to a dry pattern that will last through much of the week.
RH will improve later in the night, particularly after the cold frontal passage around midnight. This Evening Through Monday Upper ridge overhead will move east as an upper low crosses the northern US. Light snow showers are possible over northeastern WY and the northern Black Hills after midnight through Wed morning, with some snow showers possible over southwestern SD Tues night- Wed morning as the upper low deepens over the central Plains. A cold front will cross the area after midnight tonight, bringing strong northwest winds to the area during the day Tue. Upper ridge builds after low moves away, with warm and dry conditions returning toward the end of the week. A cold front will cross the area this evening into tonight, bringing strong NW winds late tonight through tomorrow.