Aikyam-Lab/Synoptic-Bench huggingface dataset:
Widespread freezing temperatures occurred last night in west side valleys from the Umpqua Basin down to the Shasta Valley. Thankfully for those still attempting grow in the area, temperatures the remainder of the week will stay above freezing in the mid-to-upper 30s. Brookings will be the oddball out, as today temperatures could climb into the low 70s with downslope winds causing additional warming in that area. Gusty northeast to east winds will persist into this afternoon, especially over the ridges, while valley winds generally diminish as the day progresses. A thermal trough along the coast will continue strong north to northeast winds and steep to very steep seas through Tuesday night, with the strongest winds and highest seas offshore south of Cape Blanco.
Low pressure will dive south of the Four Corners and cut off this afternoon and evening. Even the higher terrain of the central and western San Juans has not seen quite as high of snow totals as originally forecast, given the quick translation of the jet and lifting mechanisms to the east of the Continental Divide today. The cutoff low pressure system to the south of the Four Corners will continue to slowly spin on Tuesday. Overnight lows on Tuesday night will once again run near or below record values, however will be around 10 degrees or so warmer than on Monday night.
Southwest BL is bringing warmer and drier air into the region aloft but main period of WAA doesn't arrive until Tuesday morning ahead of next wave. Precip type may be complicated due to WAA and surface temps possibly raising above freezing. NAM wetbulb profiles do reflect a potential warm nose that depending on location/timing of precip could support a mix of ice pellets and even very light freezing rain.
Stretched upper-level troughing remains to the west, from trough north of the Great Lakes to the closed low wandering the deserts east of Las Vegas. No question the cold will grab the attention, and we will likely see a number of records in both the lowest max and min realms.
239 PM CDT Mon Oct 26 2020 High pressure at the surface will settle south tonight with a westerly gradient developing. The gradient becomes pretty strong just north of the area, with a bit of a stronger pressure gradient developing near the Buffalo Ridge after about 9z. May add some patchy blowing snow along and east of the ridge late tonight into tomorrow morning but confidence not real high. Winds might not quite be strong enough to blow around any looser snow ion the ground and the snow on the ground may not be that loose anyway as a little settling, melting and refreezing is likely to occur today. So likely something close to mixing from about 900-925 mb, which would lead towards highs in the lower to mid 30s.
Chattanooga Airport, TN 60 76 61 72 66 / 10 10 30 60 90 Knoxville McGhee Tyson Airport, TN 59 74 58 71 63 / 10 10 20 60 80 Oak Ridge, TN 57 74 57 70 63 / 10 10 20 60 80 Tri Cities Airport, TN 56 72 54 71 60 / 10 10 10 40 70.
A warming trend under weak ridging aloft will start tomorrow and last through the week.
/EC/ Tonight and Tuesday: We're currently sitting between an upper level ridge centered to the east and a digging trough over the desert SW. The trough out to the west will deepen and develop a cutoff low, and Hurricane Zeta will move over the Yucatan and skirt the upper ridge which is over the eastern GOM.
Strong ridging aloft will remain wedged into the region from the east overnight. /19/ Prior discussion below: Tonight and Tuesday: We're currently sitting between an upper level ridge centered to the east and a digging trough over the desert SW. The trough out to the west will deepen and develop a cutoff low, and Hurricane Zeta will move over the Yucatan and skirt the upper ridge which is over the eastern GOM.
The potent low pressure system pushing through the Great Basin region has brought further cooling to our area, with strong and gusty northeasterly winds across the mountain, foothill and desert zones. As the low pressure system drops further south our offshore flow pattern will continue, with the strongest winds shifting southward as well. Overnight lows tonight in this colder airmass will run around 4-8 degrees below climo and some desert locations should see temperatures bottoming out below the freezing mark. As the low pressure system begins to swing out on Tuesday, a ridge of high pressure will begin to build inland.
An upper level low will move southward over Arizona through Tuesday afternoon. This low will allow scattered snow shower to persist across eastern Arizona.
High pressure will build in over the Pacific Northwest through the middle of this week.
The trough that gave us the snow and frigid air will continue to close off and drift south and spin over the Four Corners region. An upper ridge building over the eastern Pacific will begin to fold over tonight into Tuesday morning, ushering in warmer air aloft from the northwest. The only breezy area will be the Wind Corridor, from RKS to CPR, where the return flow increases as indicated by a weak surface lee side trough.
504 PM MDT Mon Oct 26 2020 Light snow continues to stream southwest to northeast across the area, but is gradually shifting southward as the upper trough digs into the southern Rockies.
951 PM CDT Mon Oct 26 2020 Areas of rain, drizzle, and freezing drizzle continue this evening. The freezing line has nudged just slightly south over the past few hours, and may edge a bit farther south overnight before it retreats some during the day Tuesday. The next round of heavier freezing precipitation will affect areas mainly northwest of Interstate 44 Tuesday morning into the afternoon.
Radar shows a well-defined secondary cold front approaching from the west, and this boundary currently stretches from just east of Paducah KY to northwest of Memphis.
Light snow continues to stream southwest to northeast across the area, but is gradually shifting southward as the upper trough digs into the southern Rockies.
Around the overall trough pattern has been a jet stream of over 120 kts. For Iowa, this mid to upper-level flow is southwesterly, starting from near Phoenix, AZ all the way into the Northern Great Lakes Region! From 700 hPa down to the surface, high pressure has developed across the north-central Plains, and therefore has left Iowa in a dominantly north flow regime. Tonight through Tuesday Night The mid-level pattern will become a bit complex in the next 12 hours, as the trough splits into two separate waves.
/issued 259 PM CDT Mon Oct 26 2020/ Skies remain mostly cloudy across much of the Mid-South this afternoon with temperatures ranging from the lower 50s to mid 60s. Currently, a large upper level low was dropping south across eastern Utah and into northern Arizona. As the upper low moves south tonight, continued southwest flow aloft will spread moisture across the southern Plains and into much of northern Arkansas. On Tuesday, the upper low will make a more eastward turn moving across southern New Mexico. Highs on Tuesday will only reach the lower 50s across portions of northeast Arkansas with low to mid 70s expected over southern sections of the Mid-South.
820 PM EDT Mon Oct 26 2020 Weak high pressure across the area through Tuesday with warming temperatures.
Middle- and high- level clouds moving through western ND early this evening are tied to a north-south-oriented 150 kt 300 mb jet streak and weak short- wave trough, but a dry troposphere is minimizing any precipitation potential and thus our forecast remains dry through the evening. Milder air will be pulled north into the region, with highs Tuesday 10-20 degrees warmer compared to this afternoon. Broad upper level high pressure develops through the rest of the week across the Rockies, resulting in dry weather and milder temperatures for the region.
Clouds expected to scatter out tonight as high pressure drifts across the region. The ridge of high pressure drifts southeast of the region Tuesday as a warm front approaches from the Northern Plains.
Warm air advection aloft ahead of the next approaching low pressure system tonight will limit instability by late overnight. Skies are expected to clear overnight, and with fresh snowpack over the area, look for temps to fall into the low teens and single digits above zero.
932 PM CDT Mon Oct 26 2020 9 PM surface obs and KNQA radar showed a weak cold front moving through the Memphis metro area. /issued 259 PM CDT Mon Oct 26 2020/ Skies remain mostly cloudy across much of the Mid-South this afternoon with temperatures ranging from the lower 50s to mid 60s. Currently, a large upper level low was dropping south across eastern Utah and into northern Arizona. As the upper low moves south tonight, continued southwest flow aloft will spread moisture across the southern Plains and into much of northern Arkansas. On Tuesday, the upper low will make a more eastward turn moving across southern New Mexico. Highs on Tuesday will only reach the lower 50s across portions of northeast Arkansas with low to mid 70s expected over southern sections of the Mid-South.
301 PM MDT Mon Oct 26 2020 An upper ridge has moved in to the Northern Rockies and will strengthen over the next few days.
525 PM CDT Mon Oct 26 2020 High pressure at the surface will settle south tonight with a westerly gradient developing. The gradient becomes pretty strong just north of the area, with a bit of a stronger pressure gradient developing near the Buffalo Ridge after about 9z. May add some patchy blowing snow along and east of the ridge late tonight into tomorrow morning but confidence not real high. Winds might not quite be strong enough to blow around any looser snow ion the ground and the snow on the ground may not be that loose anyway as a little settling, melting and refreezing is likely to occur today. So likely something close to mixing from about 900-925 mb, which would lead towards highs in the lower to mid 30s.
Widespread freezing temperatures in west side valleys were observed this morning, so we have concluded our issuance of frost/freeze products for the 2020 growing season, not including coastal valleys of Coos, Curry, and Douglas County. This said, there is a high potential for isolated pockets of freezing temperatures in the Umpqua Basin, Illinois and Applegate valleys, a large portion of the northern Rogue valley, and the Shasta valley tonight. West side valleys,not including the Scott valley, will observe lows above freezing and steadily warming towards the low 40s through rest of the week. Winds will remain gusty on mid-slopes and ridges along the coast range, Siskiyou, and Marble mountains through Tuesday morning.
Additionally, the large trough currently in the western part of the CONUS is expected to amplify and bring a cold front pushing in from the northwest as Zeta approaches from the south. The question mark is the interaction with the trough with Zeta. The trough is generally expected to weaken Zeta as it brings cooler and drier air, but how much depends on what ends up getting here faster. It's drier and cooler. Most of the low ceilings from earlier this morning has eroded leaving VFR conditions for the rest of today into tonight.
448 PM MDT Mon Oct 26 2020 An upper trough is extending from the Dakotas into the Great Basin region, with the base cutting off near the Four Corners. Upper ridging is building in across the western third of the CONUS, moving into the northern Plains over the next several days. Warmer air will continue to work its way into the region, with warmer temperatures each day.
Additionally, the large trough currently in the western part of the CONUS is expected to amplify and bring a cold front pushing in from the northwest as Zeta approaches from the south. The question mark is the interaction with the trough with Zeta. The trough is generally expected to weaken Zeta as it brings cooler and drier air, but how much depends on what ends up getting here faster. It's drier and cooler.
The trough that gave us the snow this past weekend and delivered the unseasonably frigid air behind it will continue to close off and drift south and spin well to our south over the Desert Southwest. The positively tilted upper ridge building into the area from the northwest will usher in warm air advection from the northwest aloft which will strengthen our basin and valley inversions tonight. The only breezy areas that are anticipated are the southern and eastern wind corridor from RKS to CPR where the return flow increases as indicated by a weak surface lee side trough developing.
544 PM CDT Mon Oct 26 2020 Tonight and Tuesday: We're currently sitting between an upper level ridge centered to the east and a digging trough over the desert SW. The trough out to the west will deepen and develop a cutoff low, and Hurricane Zeta will move over the Yucatan and skirt the upper ridge which is over the eastern GOM.
Synoptically, a cut-off low is nestling into the base of the long wave trough with its center roughly around the Four Corners area by 27/18Z. Baroclinicity will result in quite the temperature gradient for Tuesday afternoon with highs in the low to mid 50s across southern Indiana and north central KY and highs in the upper 50s to low 60s across central and southern KY.
726 PM EDT Mon Oct 26 2020 High pressure surface and aloft continues to hold over west central and southwest Florida. Similar set-up for tomorrow as large scale subsidence due to the U/L ridge over the area will allow above normal temperatures to persist.
Frost and freezing temperatures are also expected for some interior valleys and coastal areas early Tuesday morning. Current thinking is that the coldest spots as of this morning will be slightly warmer tomorrow morning, but on average temperatures will be lower across the valley areas tomorrow morning as a whole.
Min temps will continue to be very mild for late October, in the low to mid 70s, which is 7 to 10 degrees above normal. Mid-upper level high pressure strengthening over the western Atlantic, as Hurricane Zeta continues pushing NW across the Yucatan and eventually northward over the central GOMEX.
Areas of rain/drizzle to continue across SE OK and NW AR, while rain/freezing rain/drizzle will prevail across the NE OK sites. /Issued 951 PM CDT Mon Oct 26 2020/ Areas of rain, drizzle, and freezing drizzle continue this evening. The freezing line has nudged just slightly south over the past few hours, and may edge a bit farther south overnight before it retreats some during the day Tuesday. The next round of heavier freezing precipitation will affect areas mainly northwest of Interstate 44 Tuesday morning into the afternoon.
Expecting mostly light snow in the Turtle Mountains area where the warm nose aloft doesn't move in until later, which is also where latest high-res guidance has the highest chance for any precipitation. Chances of precipitation decrease to the west, ending at the ND/MT border in the northwest, where the chance of freezing rain / sleet is highest compared to north central. QPF amounts look very light overall, but it doesn't take much freezing rain to make things quite slick.
/issued 932 PM CDT Mon Oct 26 2020/ 9 PM surface obs and KNQA radar showed a weak cold front moving through the Memphis metro area. /issued 259 PM CDT Mon Oct 26 2020/ Skies remain mostly cloudy across much of the Mid-South this afternoon with temperatures ranging from the lower 50s to mid 60s. Currently, a large upper level low was dropping south across eastern Utah and into northern Arizona. As the upper low moves south tonight, continued southwest flow aloft will spread moisture across the southern Plains and into much of northern Arkansas. On Tuesday, the upper low will make a more eastward turn moving across southern New Mexico. Highs on Tuesday will only reach the lower 50s across portions of northeast Arkansas with low to mid 70s expected over southern sections of the Mid-South.
1042 PM MDT Mon Oct 26 2020 An upper trough is extending from the Dakotas into the Great Basin region, with the base cutting off near the Four Corners. Upper ridging is building in across the western third of the CONUS, moving into the northern Plains over the next several days. Warmer air will continue to work its way into the region, with warmer temperatures each day.
The clouds may have an effect on lows, but unsure how much warmer as very few models are picking up on the cloud cover.
A large cut off upper low will drift from the southwest U.
313 AM CDT Tue Oct 27 2020 Freezing line has remained quasi-stationary overnight, and currently extends along a Miami to Tulsa to Okemah line. Wintry precipitation has remained rather light, mainly in the form of freezing drizzle, although expect another shot of light freezing rain this morning as precipitation developing across western TX races northeast. That said, the freezing line will gradually shift northwest this morning, with any freezing rain potential shifting to mainly Osage and Pawnee counties this afternoon.
High pressure aloft centered near the west coast will leave Utah under a dry and stable north to northwest flow aloft through midweek.
244 AM CDT Tue Oct 27 2020 Areas of light rain and snow this morning, will transition to rain as temperatures warm into the low to mid 40s this afternoon.
151 AM MDT Tue Oct 27 2020 A wave on NW flow aloft will move from Saskatchewan to North Dakota today The will bring a warm front through the area today. Temperatures will rise above freezing today which will allow the snow to begin to melt. The warmer airmass will be over the region the remainder of the week as an upper ridge moves inland from the Pacific.
The nose of warmer air is quite evident from 850mb to about 450mb. As the ridge of high pressure continues to push in from the west this week, we can expect warmer air aloft to slide over the cooler surface air at the ground where the snowcover will continue to insulate the cooler air near the surface.
Moisture from Zeta then begins to move north and interact with an upper level low moving slowly out from the southwest.
239 AM EDT Tue Oct 27 2020 An upper ridge of high pressure is centered over the Northern Florida Atlantic waters, with South Florida generally located under the southern periphery of this ridge. Given the orientation of the 500 hPa ridge, near-surface easterly flow will preside over the region through the short-term period. Maximum temperatures are forecast to be slightly warmer than seasonable, with most areas experiencing highs in the mid/upper 80s over the eastern counties and interior respectively. The western counties and Gulf coast could see maximum temperatures in the lower 90s.
/issued 726 PM EDT Mon Oct 26 2020/ High pressure surface and aloft continues to hold over west central and southwest Florida. Similar set-up for tomorrow as large scale subsidence due to the U/L ridge over the area will allow above normal temperatures to persist.
High pressure will remain over the Pacific Northwest through the middle of this week bringing dry weather and slowly warming temperatures. A weak cold front at the end of the week brings the next chance for rain, but a quick return to dry weather over the weekend appears likely.
414 AM EDT Tue Oct 27 2020 Upper level high remains anchored off the southeast coast through the period, with upper level ridging across the area. Main forecast problem today will be the low clouds and development of fog. The main concern with the low clouds will be whether or not they will scatter out at all this afternoon. Based upon how long the low clouds hung on yesterday, am reluctant to scatter out the clouds as fast especially over west Georgia where good moisture was located.
A low pressure system will glide across the Canadian Prairies today with a branch of the warm front draped through the Northern Plains.
The first concern will be for light freezing drizzle through mid-morning.
It will settle farther south today as low pressure over Alberta drags a chunk of warmer, downsloped airmass eastward with it. Temperatures will only be slightly milder than yesterday since the source region of the airmass is from the high pressure ridge.
129 AM EDT Tue Oct 27 2020 Weak high pressure across the area through Tuesday with warming temperatures.
KSGF continues to highlight band of rain moving out of northeast Oklahoma up the I-44 and Highway 60 corridors this evening however advance of freezing line has slowed and verification calls have only detected freezing over higher elevations with no impacts on roadways. 20 QPF later tonight while HRR/ARW etc maintaining the more southward axis of the QPF falling on areas where temperatures are going to be above freezing. The freezing line is expected to hang up along the I-44 corridor tonight, with temperatures in that area hovering right around 32. Right along the corridor, having temperatures right at freezing in the forecast leads to greater uncertainty and lesser impacts due to marginal temperatures and relatively warm ground temperatures.
This is a pattern that can often surprise with some light freezing rain.
1028 PM CDT Mon Oct 26 2020 High pressure at the surface will settle south tonight with a westerly gradient developing. The gradient becomes pretty strong just north of the area, with a bit of a stronger pressure gradient developing near the Buffalo Ridge after about 9z. May add some patchy blowing snow along and east of the ridge late tonight into tomorrow morning but confidence not real high. Winds might not quite be strong enough to blow around any looser snow ion the ground and the snow on the ground may not be that loose anyway as a little settling, melting and refreezing is likely to occur today. So likely something close to mixing from about 900-925 mb, which would lead towards highs in the lower to mid 30s.
HRES ensembles and deterministic CAMs have gradually hinted increasingly at slightly warmer temperatures through the afternoon, which would allow ptypes to favor a rain/snow mix or even perhaps all rain for areas within the northern portions of the Red River Valley. Highs today will climb into the lower 30s where we still have snow on the ground, with middle to upper 30s elsewhere.
If temps can get below freezing in some areas, technically it is considered freezing rain or even some freezing drizzle, however, we're having our doubts about any ice forming on surfaces and creating impacts.
The lows in the going forecast look alright, but we're adjusting the hourly trend to show that warming in some areas later tonight. The storm/trough responsible for switching us straight into winter continues to meander well off to our south through Tuesday. The trough gets cut off by a positive tilted ridge upstream, and places Colorado in the doldrums aloft so to speak.
356 AM CDT Tue Oct 27 2020 (Issued 356 AM CDT Tue Oct 27 2020) Early Morning hours: Persistent mid-level clouds are keeping areas of far southern Wisconsin a bit warmer during the pre-dawn hours.
Deep cutoff low across NM/TX will slowly eject eastward lifting a surface warm front and deep tropical moisture northward across the OH/TN Valleys which will interact with a baroclinic zone across the region.
The 500mb low has become cut off near the Four Corners area, with the elongated trough axis remaining positively tilted into the Northern Plains. This cutoff low is progged to deepen throughout Tuesday as it digs into AZ/NM, keeping the forecast area between this feature and the northern stream trough. Forecast soundings from TOP and EMP show a loss of cloud ice this evening as the lift weakens with some drying in the low levels; however, the layers of the best lift coincide with the layers of most saturation. This continues to suggest a chance for snow to transition to freezing drizzle, even if only a small chance.
As this dry air continues to push southeast, temperatures are expected to bottom out in the low single digits area wide, with below zero readings expected across the Platte River Valley where weak westerly flow should supplement the efficient radiational cooling. This would normally be a setup with the downslope component to shade warmer than guidance with high temps, but with antecedent snow cover, will stay near to just below guidance with highs today.
An eastern Pacific mid-level ridge will slowly edge toward the CONUS through mid-week, with gradually increasing temperatures.