Aikyam-Lab/Synoptic-Bench huggingface dataset:
In terms of the heat headlines, the possibility does exist that parts of the advisory and warning areas may see heat index readings below 100 due to the cloud cover and cooler temperatures from the overnight storms. Another cold front will move through the area on Sunday afternoon.
Sunday remains a bit more uncertain as the models continue to struggle with the weak cold front that has been in the forecast for the past several days.
This is the result of an upper low/associated trough located over southeast Saskatchewan and southwest Manitoba, in combination with broad ridging over the Northern Rockies. The Northern Rockies ridge will amplify and progress east Sunday, shifting through central ND evening.
Slightly more clouds and increased coverage of storms could keep high temperatures cooler than yesterday, but it will still be on the warmer side.
A weak mid-level low retrograding along the southern periphery of a broad ridge over the central Plains is progged to settle over the Texas/Louisiana border through the near term period. With the low now to our west, weak upper-level ridging builds over the local area from the north, with the associated subsidence maintaining a layer of relatively dry air aloft. In terms of heat, still expecting to see afternoon temps in the low 90's inland and upper 80's to around 90 along the coast, with heat indices generally reaching 100 to 103 degrees.
Certainly looks like more significant dry later today and tonight as the ridge builds westward and Colorado shifts under a light northwest flow aloft. The upper ridge parked over the Great Plains past several days will have collapsed by Sunday as another upper ridge gains strength over the Great Basin/Intermountain West. Circulation around this building dome of high pressure should redirect the core of the monsoon moisture plume and its embedded waves westward away from Colorado on Sunday, resulting in significantly less cloud cover and noticeably fewer t-storms.
Additionally, still have plenty of warm air aloft and morning showers/storms will work to cool the lower levels and increase atmospheric stabilization.
An approaching trough from the west will help to interact with this moisture and bring an increase chance and coverage for showers and storms. Sunday the trough out over the Pacific moves onshore and will interact with the continued monsoonal moisture surge that is pushing northwest.
Temperatures will rise back to above normal levels this weekend as high pressure strengthens over the region.
This instability forms ahead of a cold front moving through Ncntl Neb which could form a strong cluster of thunderstorms late this afternoon and this evening.
Warmer temperatures are expected for Saturday afternoon, especially inland. Temperatures will then begin to moderate on Sunday as a weak upper level trough begins to develop off our coast. But then by the latter part of the week, high pressure looks to build back in again resulting in a return to warming temperatures.
High pressure will be Southeast of the region this period. Deep layered ridge centered over the western Atlantic will stretch across the Florida Straits to southern Florida through the short term period.
239 AM CDT Sat Jul 22 2017 The upper ridge which has kept us fairly warm and dry over the past couple of days will be on the move today. Instability will also be on the low side (around 500 J/kg) during the day, but will be on the rise as we go into the overnight hours (around 1000 J/kg).
700 AM EDT Sat Jul 22 2017 A cold front will drop southward across the forecast area today with just a slight chance of a shower or thunderstorm. High pressure will settle over the region Sunday into Sunday night.
354 AM EDT Sat Jul 22 2017 The main concern for today continues to be the persistent upper ridge and hot temperatures.
Vapor imagery reveals a weak upper low moving across the marine area this morning and this will provide at least some assistance to developing thunderstorms this afternoon. Given that a little more convection is expected today, especially across the western half of the region, will show temperatures in the low to mid 90s in the western portion of the region, but in the mid 90s in the eastern half of the region. Overnight lows will dip in the lower to middle 70s. At the surface, westerly flow over the Appalachians will result in lee troughing into the Southeast. Highs are forecast to be in the lower 90s with heat indices in the upper 90s to near 100 degrees.
A weak pressure pattern surface and aloft will be in place across the region now that the upper low has moved to the northwestern Gulf coast.
NAM/GFS continue to show tremendous instability this afternoon, with CAPE values around 5000 J/kg, although the shear remains weak south of I-74 where there is more influence from the upper ridge. Upper low currently just west of Lake Winnipeg will open up a bit as it swings into the Great Lakes on Sunday, helping to finally break down the ridge over the Midwest. Cold front is expected to arrive in the northwest CWA during the afternoon, and push southeast through the evening. A couple nice days of drier air on tap, as high pressure drifts east across the Great Lakes.
Synoptic Setup: Short term begins with hot high pressure over the western half of the CONUS. A ridge has risen out of the this airmass over the western half of Montana and southern Alberta, while a previous cool airmass is exiting into the Dakotas. Farther West a closed low resides over the British Columbian coast. Today through Sunday: Northwest flow today will give way as the as the RIdge to the west builds in strength and moves over the central Montana overnight. COnditions should be dry through all these periods as the entrance of the ridge should stabilize out the atmospheric profile. The latest 00z models continue with a closed low tracking across southern Alberta and Saskatchewan with a southward extending dry cold front through western Montana Sunday evening.
Low amplitude mid level ridge will remain centered just to our west but its influence over our area will begin to weaken a bit. Will keep PoPs on the low side.
especially south of the highway 24 corridor. Drier and cooler air will then prevail for the first part of the upcoming week. Short wave and associated secondary cold front to swing south Sunday into Sunday evening.
Today and Tonight: The upper ridge will continue weaken across the area today, and this combined PWATS ranging from 1. High temperatures will be a little cooler across most of the area, with highs in the low/mid 90s. Although the temperatures will be a touch cooler than yesterday, dewpoints in the mid 70s will cause heat indices to exceed 105 degrees for areas generally along and north of I-20. /15/ Sunday through the end of the coming work week: Still looking like our region will get a bit of relief from the hot and humid conditions through the first portion of the coming week as the eastern extent of the heat ridge yields to a very weak cut-off upper level disturbance over the Lower MS Valley vicinity.
The rain is gradually diminishing from north to south as the low level jet veers over northern IL. Drier air will be spreading into the area as the day goes on, although lingering moisture in the low levels will lead more broken cloud cover. The vorticity advection and associated trough sliding through central WI may trigger a few showers and storms tonight north of I-94. The warm and humid air will persist over the area, with highs in the lower to mid 80s today and lows tonight in the upper 60s.
410 AM CDT Sat Jul 22 2017 Increasing Louisiana area shower and thunderstorm coverage early this morning in association with the northern Gulf of Mexico upper level low will gradually work its way westward and into our area over the weekend as the low continues heading westward. Models continue to indicate lowering precipitable water values during much of the upcoming week as mid/upper level high pressure attempts to build into our area, but for now we'll need to keep some low mainly daytime rain chances in the forecast.
Flow aloft becomes more E-SE tonight late tonight and potentially southerly on Sunday as models suggesting inverted trof pushing through.
A weakness finally comes late this weekend to the northeast quadrant of the strong upper high. This will be associated with a trough moving through the upper Mississippi Valley and Great Lakes regions.
1021 PM PDT Fri Jul 21 2017 A warm front will result in increasing cloud cover over the northern mountains with some showers expected in the east slopes of the northern Cascades tonight. Clouds will clear on Saturday with warmer temperatures back up into the 90s this weekend.
The upper level high pressure responsible for the heatwave was positioned just to the west of Middle Tennessee this morning. Through the rest of the weekend, this high will gradually weaken over our area. This will probably not make much difference in terms of temps and humidity today with models showing slight building of the low level warm air. A few of these storms could become strong to briefly severe in the high cape environment.
The cold front has moved well into NM. Water vapor, especially the low level water vapor imagery from GOES 16, was showing drying across se WY and far ne CO. Temps today will be about 8-10F cooler on the the plains then the last several days. Min temps should cool into the 50s and 60s plains with 30s to L50s over the higher terrain. \/Hodanish The plume of monsoon moisture stays south and west of the area Sunday with a few thunderstorms forming in and near the mountains, but considerably less thunderstorms at the lower elevations.
Residual cloud cover from this convection as well as a blocking of the richest moisture return has greatly limited instability across central MN & west-central WI. Northerly flow will keep temperature slightly below normal as high pressure works in from the north.
325 AM CDT Sat Jul 22 2017 Ridge of high pressure remains over the region this morning and will result in another hot and muggy day across southeastern Kansas and the Missouri Ozarks. The ridge will start to flatten some late today and especially tonight. An upper level trough will spread south across the area Sunday/Sunday night, resulting in an upper level ridge building up to the west of the area. Temperatures will not be quite as warm on Sunday as today with the ridge flattening, but they will still be on the warm side. 850mb temperatures will be in the lower 20's C allowing highs in the lower to middle 90s. Temperatures will also be slightly cooler, but a big cool down will not occur by any means.
339 AM EDT Sat Jul 22 2017 A cold front will drop southward across the forecast area today with just a slight chance of a shower or thunderstorm. High pressure will settle over the region Sunday into Sunday night.
1208 AM MDT Sat Jul 22 2017 Water vapor imagery shows the monsoonal plume overhead with thunderstorms popping up over the higher mountains this afternoon. The cold front has passed south through our eastern plains counties, and a more northeast upslope fetch along the Laramie Range should aide in storm development along these mountains. Additional development along the Cheyenne Ridge (I-80 corridor) is still progged by most models through later this afternoon and evening. High temperatures will be roughly 5-10 degrees cooler in the post-frontal environment, and temps aloft will cool a couple of degrees as well. Moist southeasterly return flow will aide in destabilizing the atmosphere some through the afternoon, especially along the eastern side of the Laramie Range and the Cheyenne Ridge. Will keep chances for storms confined to the higher mountains for now.
High pressure will provide dry, hot and sunny weather today with another similar day on tap for Sunday. Late in the day Sunday the region will come under the influence of a closed upper low that moves into position just off the Northern California coast.
136 AM EDT Sat Jul 22 2017 A weak cold front moving southward from Quebec may bring an isolated shower or thunderstorm near the international border through this evening. Northwest winds Saturday and Sunday will bring slightly cooler temperatures, with afternoon highs in the upper 70s to lower 80s.
Hot and dry conditions will persist for the short term period, with development of upper level ridging over the region. Surface trof may limit winds over much of the region, it will be a prefrontal day, so will need to take closer look as situation develops and front approaches.
Temperatures will rise on Sunday in the southerly flow, bringing afternoon temperatures in the lower valleys near 100.
400 AM CDT Sat Jul 22 2017 Upper low will keep the area under enough sh/ts and cloud cover to keep heat index values low enough to keep the oppressive heat down. A strong short wave, over southern Canada, embedded in the larger upper trough is moving southeast this morning.
1232 AM CDT Sat Jul 22 2017 VFR with a small window for late-afternoon TS near LBB and PVW under a weak upper low.
Unfortunately, another heavy rain/flooding event across the area overnight, with persistent moisture transport up and over a low level warm front into northern/central Iowa delivering another bout of very heavy rains. Thankfully, that activity is beginning to wane and shift south the past few hours with veering of the low level jet/moisture transport axis, but with ongoing short term flooding of concern as water works through the system. Associated broad ascent on the southern flank of that wave and along a trailing trough axis interacting with MLCAPE values around 2500+ J/kg later this afternoon (barring unforeseen cloud issues) should be enough to ignite some convection just to our north during the afternoon hours, with some of that activity likely sneaking in our direction for the late afternoon and evening.
Tonight Through Sunday Ridge of high pressure will weaken a bit and shift to the west this weekend. This will allow a weak cold front to approach from the north.
This will be along and ahead of an approaching cold front from the northwest. Dewpoints will steadily increase ahead of the cold front, reaching into at least the mid 60s by Saturday afternoon. Some of the thunderstorms ahead of the cold front could be strong to severe with the main threats being gusty winds and large hail from the strongest storms. Late tonight through Saturday afternoon winds across the western half of the lake will increase to around 20 to 25 knots ahead of an approaching cold front.
321 AM CDT Sat Jul 22 2017 A cold front will push into the area this afternoon, which will have several effects on the weather, in the near term, as well as in the coming days. For today, with the cold front moving into northern MO by the afternoon, there will likely be some compressional warming along/ahead of it. Overall, temperatures along and ahead of the front look to be 1 to 2 degrees warmer than yesterday. Fortunately, the cold front progresses through the area, pushing convection south as it does. While it will be cooler on Sunday, it's still likely to be above normal and still humid with heat indices around 100. The real shot of cooler and drier air comes with a secondary front that should move south into the area Sunday night.
455 AM MDT Sat Jul 22 2017 08z surface analysis showed cold front south of the CWA with weak high pressure settling in. Today through Sunday, upper ridge will build over the western US, slowly moving into the northern Plains as it flattens somewhat.
308 AM EDT Sat Jul 22 2017 High pressure will dominate the weather for the weekend with below seasonal temperatures expected.
VFR conditions will prevail next 24 hours under upper-lvl ridging and return flow.
The upper level low across the upper TX coast tonight will move slowly westward Sunday.
Meanwhile, the evening water vapor imagery depicts a weak but broad upper low over the NE Gulf, which should continue to slowly retrograde W along the Gulf Coast into Srn LA through Saturday.
Expect VFR conditions to prevail across the Rio Grande valley and the northern ranchlands Saturday as the 500mb ridge across the south- central United States continues to provide subsidence across the area. VFR conditions to prevail tonight and Saturday with high pressure overhead maintaining drier air through the atmosphere. An upper level low pressure area over the North Central Gulf of Mexico to drift west while weakening tonight and Saturday. /issued 258 PM CDT Fri Jul 21 2017/ SHORT TERM (Tonight through Saturday Night): Not much change to the short term forecast, as the summertime ridge remains the main influence on local weather. The ridge will continue to produce hot temperatures areawide.
High pressure continues to influence our area with dry conditions tonight. A low pressure system may brush our far nw cwa and bring some high level clouds to the region.
Saturday through Sunday night Another day of high temperatures and elevated humidity is expected across the area as the upper level high pressure remains in control. The upper ridge does contract to the west as the period progresses but overall only minimal relief is expected on Sunday.
Otherwise temperatures will be slightly cooler along and north of the boundary. Weak NW flow will be overhead Sun with a trof over the GtLakes. some amplification will occur with trofs over the Ern/Wrn USA and a broad ridge developing over the Rockies. The trof moving across Canada will drive a cool front across the Nrn 2/3 of the CONUS.
236 AM MDT Sat Jul 22 2017 08z surface analysis showed cold front south of the CWA with weak high pressure settling in. Today through Sunday, upper ridge will build over the western US, slowly moving into the northern Plains as it flattens somewhat.
306 AM CDT Sat Jul 22 2017 Outflow boundary/bore/gravity wave is currently approaching from western KS, stemming from earlier thunderstorm activity across the High Plains. Today will be the last HOT day across the region, with downslope/compressional warming ahead of the approaching cold front.
600 AM CDT Sat Jul 22 2017 Ridge of high pressure remains over the region this morning and will result in another hot and muggy day across southeastern Kansas and the Missouri Ozarks. The ridge will start to flatten some late today and especially tonight. An upper level trough will spread south across the area Sunday/Sunday night, resulting in an upper level ridge building up to the west of the area. Temperatures will not be quite as warm on Sunday as today with the ridge flattening, but they will still be on the warm side. 850mb temperatures will be in the lower 20's C allowing highs in the lower to middle 90s. Temperatures will also be slightly cooler, but a big cool down will not occur by any means.
TUTT low approaching from the Nrn Gulf coast is becoming less symmetrical on satellite imagery, with strong mid level subsidence suppressing convection and pressing the low into an elongated e-w shear axis. This illustrates the dominance of the mid-to-upper level ridge covering the Central US and is justification for undercutting PoPs for this weekend and beyond.
The GFS ensemble mean maintains an upper level trough/low at 500-mb affecting the extreme NW Gulf of Mexico/SERN TX during the period. Thus, the combination of the upper trough/moisture to contribute to convection Today, primarily over the NERN CWA.
However, considering temperatures are in the low 80s at this time (4am CDT) and warm air aloft (H850MB temps in the lower to mid 20s Celsius) any breaks in the clouds will allow for a rapid warm up. So will maintain close to guidance, with highs in the lower 90s at most locations. A building ridge aloft over the Four Corners expands onto the Plains by midweek, helping temperatures remain summerlike, then retreats west late week.
341 AM CDT Sat Jul 22 2017 (Today and Tonight) Upper level ridge continues to be the dominant weather player across West Central Texas, with continued hot and dry conditions for today.
High temperatures look to be a degree or two cooler over the weekend across central and eastern areas where height values are lower and moisture higher.
A cold front stalled near the Nebraska Panhandle should kick south this afternoon, and thunderstorm coverage should once again increase. Main focus then will be on cold front where there may be a narrow corridor of better lift as this moves through the region. Guidance hasn't been consistent on location of best precip signal (though it is generally depicted along/ahead of cold front). Even on the low end there is enough instability depicted by models to support at least a limited severe threat across our entire CWA this afternoon/early evening.
An approaching cold front, and a much weaker, nearly non-existent surface pressure gradient will eliminate much of the mixing Saturday afternoon, driving heat indices will above 100 degrees ahead of this surface front.
339 AM EDT Sat Jul 22 2017 As a weak cold front moves southward from Quebec and through the North Country this afternoon, an isolated shower or thunderstorm is possible across central and southern areas, otherwise dry conditions are expected through the weekend as high pressure settles overhead.
359 AM EDT Sat Jul 22 2017 High pressure remains off the southeast coast. An upper level trough of low pressure will move over the northeastern US early in the week. The way I'm playing it is that there will be a decent amount of sunshine/heating during the morning, then increasing clouds in the afternoon given dewpoints in the lower 70s as well as the approaching MCS which may cap the temp rise in the afternoon.
638 AM EDT Sat Jul 22 2017 High pressure will dominate the weather for the weekend with below seasonal temperatures expected.
There's also a synoptic scale cold frontal boundary beginning to work into the region from the northwest. Tonight: latest trends in CAM solutions supports the bigger picture synoptic-scale setup in that they begin to force convective initiation on the cold frontal boundary moving through the region by between 22Z and 00Z between Bismarck and Mobridge and spread strong to severe convection southeast through the forecast area. Not sure the low-level shear will be all that favorable for tornadoes. Saturday: The cold front is forecast to be well east of the cwa as the sun comes up Saturday. Across central and north central South Dakota, these post frontal northwest winds will usher much drier air into the region before it's drawing cooler air into the region.
500 mb ridge to our south has weakened a bit and should continue to do that today. Very weak cold front continued to push south across the area and should be down into KS and MO this afternoon. Temperatures today should be a bit cooler most areas, but still lots of 90s.
Upper low will continue to propagate east along the international border region today. Although low level forcing looks to be lacking, any lingering outflows from current convection could combine with respectable cold pool with upper low to produce afternoon convection mainly over the ne FA. With low freezing levels cannot rule out some marginally severe hailers with stronger storms. As upper low continues to propagate east any lingering showers/T should be confined to the far ne this evening. With quite a bit cooler airmass in place highs in the 70s expected.
These winds will be felt more over northern portions of the CWA, while the lowest RH will reside over all of central SD. Fire zone 269 was tricky in that RH was a bit more marginal with current forecast in the low to mid 20s.
Lastest temps were still in the upper 70s to mid 80s with dew points not far behind in the low to mid 70s, so a rather sultry night is ongoing across the region. The upper high over the region will break down more as moisture from the southern low weakens the ridge. High temperatures in the low/mid 90s, along with dewpoint values into the low/mid 70s will yield more heat indices into the upper 90s NE Alabama and adjacent southern middle Tennessee, to 107-109 across parts of NW Alabama.