Aikyam-Lab/Synoptic-Bench huggingface dataset:
The big story for the near term remains very cold temperatures, as arctic high pressure stretches from eastern Ontario into Ohio. The pressure gradient (albeit a relatively weak one) on the east side of the ridge has maintained gusty wind speeds between 10 and 15 knots over eastern parts of the forecast area/Adirondacks, resulting in stinging wind chills between -20 and -15 degrees.
This is expected to allow southerly winds to bring warmer temperatures to the area for Friday along with some early sunshine. With the southerly winds, afternoon temperatures should make it into the lower 40s near the Arkansas line to the middle 30s across central Missouri.
1015 PM MST Thu Dec 28 2017 High pressure will persist across the southwestern US keeping Utah and Colorado in dry northwesterly flow.
920 PM PST Thu Dec 28 2017 At 9 PM PST, water vapor satellite showed an upper-level ridge centered just west of southern California, and fog imagery showed a few patches of fog over the coastal waters south of San Diego. Sunny and warmer through Friday then cooler for the weekend.
250 AM CST Fri Dec 29 2017 Still some uncertainty with regards to freezing fog or freezing drizzle potential this morning. The entire area is expected to warm above the freezing mark by mid/late morning with afternoon temps warming into the 40s and lower 50s.
On Friday, a trough located in the northern Great Lakes region will act to push a cold front through the area Friday night.
Those who don't like winter will find today the most tolerable day of the coming week, with highs topping out just either side of freezing and light winds.
1130 PM CST Thu Dec 28 2017 Northwesterly flow with fast-moving embedded short wave troughs will remain in place through the end of the week. 5PVU pressure plots show a wave cresting the upper ridge positioned over the west coast. Models show this wave moving into the region tomorrow morning and spreading a chance for snow and possibly freezing drizzle to parts of northern and northeastern Missouri. Forecast soundings in this area show a deep saturated layer that is below freezing but not cold enough to introduce ice crystals. This likely lack of ice crystals may result in some freezing drizzle. But with the current suite of model data, it looks like freezing drizzle.
This suggests that the warm front has indeed moved northward. VFR conditions will continue into this evening with IFR/LIFR returning to most locations tonight ahead of a cold front offshore. South winds will continue to increase and seas will steepen tonight, especially north of Cape Blanco as low pressure moves inland to the north. A stronger low pressure system will move north of the area Friday and a cold front will move in from the west.
143 AM EST Fri Dec 29 2017 Strong high pressure to the north will continue to direct cold air into the region. Low pressure off the Southeast Coast will move farther offshore today.
High pressure will then build in at the surface until an Alberta clipper noses into the region from the northwest late in the day Friday.
Attention/concern turns to warm air advective/isentropic lift driven snow pushing into the area Friday associated with another mid-level trough dropping through the Northern Plains/Upper Mississippi River Valley Region.
The cold front has moved through much of the CWA, with temperatures back below zero across the north central and northwestern counties. A strong arctic high pressure is progged to slide out of the Canadian high plains into the Northern and Central Plains over the weekend.
Winds should remain light through the period with high pressure building across the region.
Temperatures tonight will be a few degrees warmer compared to the last few nights with lows dropping into the teens to single digits by daybreak. The southerly winds will spread warmer air north with the main forecast challenge to be how far north given the existing snow cover.
Winds behind trough axis will be westerly, so any additional snow showers will be confined to the lee of the lakes. It still looks like the ridges will see the most snowfall.
With a modified Arctic airmass in place, overnight lows should be similar, if not a few degrees warmer than last night. An Acrtic front will move into central/west central Kansas by Friday afternoon but locations along I-70 should be able to realize high temperatures in the low 40s before temperatures rapidly fall off behind the front. A deep upper trough extending from Hudson Bay into the central Canadian prairies will move southeast into the upper Midwest and Great Lakes Friday night.
This is leading to temperatures being a little warmer than forecast tonight, but the air is dry enough that any clearing before sunrise could result in a quick drop in temperatures early this morning. Ahead of the strong cold front this weekend, WAA and isentropic lift on Friday night will result in increasing cloud cover and keep minimum temperatures "warm" mainly in the mid to upper 20s.
340 AM EST Fri Dec 29 2017 Arctic high pressure remains over the area today.
Generally light winds will gradually shift from northeast to southeast through the day as high pressure centered over central Arkansas shifts east of the area. this leads to readings just below freezing as opposed to the upper 20s for the far nern zones tonight.
The flow aloft will increase enough to support wind gusts to 70 mph along the higher reaches of the Continental Divide from the Monarch Pass area northward. Elsewhere, gusts to 60 mph will be possible in and near the mountains with gusts to 30 mph possible at the lower elevations. Winds will gradually ramp up in the high country this evening and then reach full strength after midnight. A ridge of high pressure over the West Coast will persist, producing northwest flow aloft across the region.
Our previous discussion mentioned the upcoming blast of cold air, and our forecast of temperatures at or below freezing at BNA for 5 days, and possibly more. Records going back to the late 1800s indicate that the record for the longest number of calender days below freezing at Nashville, stands at 9. We have determined our forecast average temperature for the upcoming cold outbreak of 12/31/17 (cold front arrives) through 1/4/18 (end of the forecast period). We are expecting 16 degrees around the time of the Music Note Drop in Nashville and 12 degrees for the low at BNA.
340 AM CST Fri Dec 29 2017 High pressure centered over the Mississippi Delta this morning. With high pressure over the area today, most areas will see considerable sunshine today.
332 AM EST Fri Dec 29 2017 Low pressure off the Southeast Coast will move farther offshore today.
/issued 945 PM CST Thu Dec 28 2017/ Made a few minor temperature changes for the lower parts of East Texas for lows tonight and adjusted the cloud cover for much of the region. All eyes are still on the strong cold front and major Arctic air intrusion expected this weekend.
1026 PM MST Thu Dec 28 2017 Very cold upper trough persists across the eastern two-thirds of the CWA, as deep northwest flow continues across the northern Plains. Frontal boundary sits just west and south of the CWA borders with temperatures ranging from the single digits across northwest SD to the lower 20s across northeast Wyoming and southwest South Dakota. A second reinforcing cold front will then drop southward Friday afternoon and evening bringing the area very cold temperatures through the weekend.
At the surface, high pressure will weaken and move east. Ahead of the front on Friday, most areas will climb above freezing by afternoon.
Surface analysis at 07Z had an area of low pressure over northwest Iowa with a frontal boundary extending west across Nebraska. The upper high over the southern Rockies will extend out into the central and southern Plains with the southern extent of the westerlies across Nebraska and Iowa. Main concern for the day will be heat with the thermal ridge building eastward across the CWA. Towards the end of the period, the western CONUS ridge will rebuild northward and place the region in northwesterly flow.
Storms should initiate along the higher terrain, with steering flow generally pushing storms to the west-southwest after initiation. The high pressure ridge flattens early in the week and then rebuilds over the region later this week. As the ridge rebuilds across the west late this week, temperatures are expected to warm above average. Cooler temperatures and increased low level moisture are expected early this week with higher chances for wetting rains, though gusty and erratic outflow winds should still be anticipated.
VFR conditions will prevail next 24 hours under ridging and return flow. /issued 118 PM CDT Mon Jul 10 2017/ The upper ridge centered over the 4 Corners region this morning will spread east to the Atlantic over the next couple of days. However by the weekend the ridge will become centered over the west once again which could allow disturbances to track down into the area on northerly flow. At the surface S to SE flow will continue for the foreseeable future keeping the low levels moist. Dewpts range from the lower 60s in the east to the upper 40s in the higher elevations of the west. Have only had a few random echos on radar today but satellite shows CU developing across the mountains so will go ahead and add isolated pops to the higher elevations into this evening.
Thunderstorms are initiating along the higher terrain of northern Arizona this afternoon.
Synoptic setup: A large area of hot high pressure resides over the southwestern quarter of the CONUS. A ridge spur runs north of this through eastern Wyoming and Montana. A weak trough runs down the coastline from British Columbia to northern Oregon. This afternoon through this evening: Near the surface a lee side mountain trough has set up over eastern Montana and is low pressure center over southern Saskatchewan. This low is being driven by the jet aloft and kicking the aloft ridge into the Dakotas.
Looking ahead into tonight, it appears that elevated thunderstorms will break out north of a surface warm front along the Canadian border in North Dakota. There is decent support for this from the low level jet and 850mb warm advection. Warmer 700mb temps look to limit thunderstorm formation until later Tuesday afternoon across the southern half of the FA. Looks like an inverted trough will hang back into this area, helping to keep this pcpn around. High pressure begins to move back into the FA Wed night, ending this lingering lighter pcpn.
Upper trough will continue to be the main player in our weather over the next several days, although flow will become progressively more zonal, with higher heights owing to some warming and increasing instability through midweek.
Very warm mid week with a cold front in the vicinity late in the week into the weekend. With plenty of low level moisture in place and the expected short wave trof to move along that boundary, expect scattered showers thunderstorms to develop in the daytime heating. Some areas in the lowlands may top out in the low 90s by tomorrow afternoon. As upper level ridging builds to our south, upper flow is expected to remain zonal. Increased moisture will combine with warm temperatures to produce heat index values in the mid to upper 90s across the lowlands. Still eyeing a cold front that will approach the area by late week.
As an upper level ridge moves into the Central Plains a weak inverted trough will be positioned over the region.
REST OF THE WEEK: The western Atlantic ridge is still in place draped across central Florida.
Mid level trough across the Appalachians will slowly lose its hold across the Tri-State region today as the western Atlantic ridge begins to build in from the east. Storms will also fire on the western periphery of the Atlantic ridge in the FL Big Bend counties and SW GA. Highs today will reach the lower to middle 90s.
400 PM EDT Mon Jul 10 2017 High pressure centered near Bermuda will bring fair and mainly dry weather for the bulk of today. Mainly dry, and slightly cooler weather will arrive for the weekend. High temps will be slightly above normal - ranging from the upper 70s across the highest terrain of the north and west.
228 PM CDT Mon Jul 10 2017 Hot and dry conditions across most of the area through the work week due to the elongated upper high over portions of the southern U.
The latest water vapor satellite imagery and upper air observations reveal high pressure in the mid and upper levels of the atmosphere centered near the 4-corners region. We could see a few late afternoon and early evening showers and storms along the Highway 77 corridor today given daytime heating and adequate low-level moisture.
414 PM EDT Mon Jul 10 2017 A strong cold front will approach on Tuesday and sweep across the area Tuesday evening.
There is a low pressure disturbance over the central mountains and just north of Challis this afternoon moving northeast into Montana.
Small short wave moving through the upper ridge over the northern Plains is currently over eastern WY and setting off thunderstorms along the front over eastern WY and northern Black Hills. Stronger system will track through eastern MT into ND tonight with potential for severe storms and flatten upper ridge and drag stationary front across the Dakotas Tuesday.
The eastward progression of an upper trof moving along the northern tier of states from the Rockies to the Great Lakes will flatten or elongate the upper ridge axis from the southern Rockies across the Ozarks thru mid-week. Temperatures will continue to warm under the ridge aloft with increasing south to southwest low level flow across central and eastern Kansas.
1203 PM CDT Mon Jul 10 2017 Seasonably warm and humid conditions are expected today across the region, as highs warm into the low 90s. Tonight, lows will fall into the low to mid 70s for most.
320 PM MDT Mon Jul 10 2017 Upper level high pressure drifting eastward along the Colorado/New Mexico border this afternoon, with isolated/sct tsra rotating around the high across much of the higher terrain as of 21z. On Tuesday, upper high shifts slowly into NM, with a subtle increase in wly flow across CO through the day. Given increase in moisture and instability expect an upturn in convection most areas, including the eastern plains as weak sly steering currents will help give convection a shove eastward away from the higher terrain in the late. Max temps may drift down just a degf or two with upper high slipping away, though readings will still approach 100f across the lower Arkansas Valley for another day.
Part of the reason is that a weak-upper level trough that brought enhanced afternoon convection across the ArkLaTex has shifted south into Acadiana today while upper-level ridge has been strengthening in its place. A similar pattern to persist through the Tuesday characterized by upper-level ridge maintaining sparse afternoon convection north of I-20 with scattered convection south. Afternoon high temperatures to climb into the lower 90s on Tuesday.
330 PM CDT Mon Jul 10 2017 Mid-afternoon sfc analysis high pressure remaining centered over the ern Gulf and maintaining a moist onshore low-level flow across the region. meanwhile mid/upper-level ridging is noted from the 4-Corners region nwd through the lee of the Rockies and Plains states with some troffing noted moving into the Appalachians. The region looks to remain in a rather persistent pattern the next few days with ridging staying mainly to our west while srly low- level flow keeps us moist and unstable.
The only TAF location with high enough confidence to include thunderstorms in the forecast is KGUP, and even so confidence is on the lower end at that location. Mid level high pressure will be parked over the four corners region today. A short wave trough well to our north will flatten the high pressure area Tuesday, pushing the high center a little to the south.
Given the high instability and observed 700- 500 mb lapse rates over 6C/km, there could be a couple of strong to locally severe storms this afternoon, which is typical of summer. Overnight lows will generally be in the low to mid 70s.
1125 AM MDT Mon Jul 10 2017 Upper-level ridging will begin to flatten today, setting the stage for an active start to the work week. This will serve as a focus for convective development, first across the high country before spreading across the remainder of the CWA after 21z or so. Tuesday looks to be fairly typical for mid July for this area, on the edge of a ridge with only very weak ripples w/in the flow.
Quasi-zonal flow transitions into more northwesterly flow for the second half of the week as the ridge over the Rockies and High Plains strengthens.
The upper trough in the Northeast begins to flatten on Tuesday with a more zonal pattern in the upper levels persisting through the end of the week. Low level ridging builds in under the zonal flow leading to warmer temperatures and scattered thunderstorm chances each afternoon.
424 PM EDT Mon Jul 10 2017 Upper air pattern consists of a 500 mb trough in the Pacific NW and more troughing across the ern U. There is also a ridge across the Rockies.
Temperatures in the low 90's will combine with dewpoints in the low 70's to result in heat indices near and slightly above 100 degrees. 2 inches and dewpoints in the lower to mid 70s. These storms will have potential, given the high amount of moisture in the air, to bring efficient, heavy rainfall. Zonal flow will take hold across the northern tier of the CONUS while a building upper ridge will expand across our region. Highs should easily reach into the lower 90s during this time period.
Not too much to update this morning with high pressure dominating the region, bringing clear skies and warm temperatures. Highs today should be in the low to mid 90s for most of the mid state, with mid to upper 80s on the Plateau. Temps will be slightly warmer tomorrow afternoon and should be the warmest of the week across the area.
A slightly cooler day today across Southwest Washington and Northwest Oregon.
545 PM EDT Mon Jul 10 2017 A dying cold front will approach from the Great Lakes this evening, then stall out just north of Pennsylvania for the next few days. Much high humidity, along with cloud cover, will result in a much warmer night than recent ones, with min temps mostly between 65-70F.
A weak trough will bring slightly cooler and more seasonable temperatures for the interior portions of Northwest California while coastal communities remain influenced by the marine layer. An upper level trough moving into the Pacific Northwest this morning has pushed the upper level ridge a bit farther to the east. The trough remains in place tonight and Tuesday.
On Tuesday, onshore flow will increase as high pressure over the central Atlantic strengthens. Upper level flow looks pretty weak as well as the ridge axis remains well out to sea.
254 PM EDT Mon Jul 10 2017 Surface analysis this afternoon shows low pressure over Iowa with broad southwesterly flow ahead of it across the mid-Mississippi and lower Ohio River Valleys. Plan on lows in the lower to middle 70s, warmest in the urban centers.
301 PM PDT Mon Jul 10 2017 Our forecast area remains sandwiched between high pressure centered over the four corners region and an upper level trough centered off the Pacific Northwest and Canadian coasts. Ultimately, the primary difference in the models is that, while the four corners high amplifies, the trough offshore strengthens and nears us over the weekend.
In any case, kept higher PoPs in the northeast 2/3rds of the CWA, with some expectation of weakening further east and south due to the lower CAPE forecast. Mid-level troughing will gradually transition to a more zonal flow regime, with rising 500 mb heights pointing to a continued warm and humid trend.
/issued 358 AM CDT Mon Jul 10 2017/ (Today and Tonight) Upper ridging will continue to build in from the northwest today, suppressing most thunderstorm development. High temperatures will be in the mid 90s again today, with lows tonight in the lower 70s.
Nothing special, with mountains favored until later in the week when we will watch an easterly wave currently developing on the southeast periphery of the high move across central to northern Mexico.
Incoming Pacific upper trough will cool temperatures to normal through Tuesday night.
The WFO PAH forecast area will be centered under middle and upper level ridge, as it become more compressed with time.
1116 AM MDT Mon Jul 10 2017 An upper level ridge will be centered near the Four Corners region today. Temps will again be above average, with 90s to lower 100's over the plains and mostly 80s in the high valley locations.
RAP analysis showed our forecast area to barely be under the southeast edge of the high. Models show a wobbling ridge starting Tuesday, and that trend continues for most of the week. We never end up squarely under the high, which means highs will only reach a few degrees above normal, at the most.
However, given the low chances we will not mention at this time. Temperatures have climbed into the low to mid 90s as of 3 PM, with a few more hours of heating still to go. Tomorrow should be a degree or two hotter as conditions dry out even more, so forecast highs in the low to mid 90s for Tuesday afternoon look on target. Overnight lows have continued to be a couple degrees cooler than some of the models have indicated, so will stay on the cool side of guidance for tonight's lows.
Hot and humid conditions will persist through the work week as an upper ridge persists over the area. PW values in this area are now well over 2 inches with surface dewpoints in the low 70s. Lows in the low 70s. The big story for Tuesday will be the increase in temperatures as the subtropical ridge takes over and thickness values climb to near 1440 meters. With highs in the low 90s and some dewpoints in the low 70s heat indices should remain in the upper 90s but a few 100 degree readings are possible. Low temperatures in the low 70s.
Models in good agreement with the idea of expansion of mid-level ridge across the southern plains and southern Rockies this week. By Tuesday evening, we could see thunderstorms drift into the far northwest part of the forecast area from the higher terrain.
A weak backdoor cold front extends across central Nebraska into the central panhandle. Rather large differences exist between the GFS and NAM models today as 850 temperatures are 6C warmer with the GFS at North Platte i. Favored the warmer solution for highs today, with highs of 98 at North Platte and Ogallala and 102 at Imperial, to 92 at Valentine and 88 at O'Neill. Lows from the lower to mid 60s northwest to the upper 60s southeast. Temperatures Tuesday will also rise into the upper 90s with a few locations south of I-80 even rising into the low 100s.
126 PM EDT Mon Jul 10 2017 High pressure centered near Bermuda will bring fair and mainly dry weather for the bulk of today. Mainly dry, and slightly cooler weather will arrive for the weekend. High temps will be slightly above normal - ranging from the upper 70s across the highest terrain of the north and west.
The mid-level moisture and instability with the high pressure should remain more south into CO as well for only a slight chance of convection across the southern half of Sweetwater County.
Tonight: Scattered showers and thunderstorms are expected to develop in the 3 PM to 5 PM time frame over the high terrain Ferry, Stevens, Pend Orielle, Boundary, and northern Okanogan counties. Cells will likely form over mountain ridges and weaken as they move off the high terrain with a cell motion of northeast at 15 to 20 mph.
We expect scattered showers and thunderstorms over the high terrain along the Canadian border this afternoon into the evening.
354 PM CDT Mon Jul 10 2017 Increased temperatures for tonight, especially across the southern half of the forecast area, as a warm front slowly moves across the region overnight into Tuesday. Despite dewpoints rising into the low 60s (mid 60s east) relative humidity values west of the James River Valley will fall into the 20 to 30 percent range. The grassland fire danger index will still likely be in the high range for areas along and west of the Missouri River.