Aikyam-Lab/Synoptic-Bench huggingface dataset:
At the surface, weak high pressure resides across the area, with a cold front across far northern Montana and North Dakota. On Saturday, the cold front across northern Montana and ND will slide into the CWA and back into the eastern edge of the Black Hills by early afternoon. A low stratus cloud field will follow the cold front and as it makes it into the Black Hills area, light easterly upslope flow may produce areas of fog and freezing fog along the eastern edge of the Black Hills. Winds will remain east to southeast through Saturday evening with areas of fog and freezing fog develop across the area. Strong upper trof will reach the Great Basin region late Saturday, then intensifying over the Rockies Saturday night.
and tomorrow will remain mild with temps in the lower 40s/upper 30s.
But given temperatures near or even a little above freezing, and considering that the FZDZ will be falling into fresh snow, at this point do not anticipate needing to extend the advisory to cover the FZDZ.
Shallow cool air associated with a Canadian high pressure system is slipping south into North Dakota. A vigorous short wave trough just off the southern California coast is seen on the water vapor imagery loops. A 140kt jet is depicted by model data moving south on the western side of the trough. This jet streak will round the base of the trough tonight and swing northeast toward the northern plains Saturday.
Weak wave of low pressure approaching from the midwest is associated with a broad area of warm air advection and isentropic lift over the Ohio Valley and Great Lakes this afternoon. The most significant risk with this system could be a little freezing rain around or just after daybreak. High pressure moves east at the surface and upper level heights rise Saturday night shutting off the showers.
652 PM EST Fri Dec 23 2016 Fast moving low pressure will bring showers to the region after midnight and Saturday morning. Heaviest rain amounts will line up just ahead of the main trough axis spreading southwest to northeast. It is conceivable that some locations near freezing could wet-bulb down to below freezing, creating some minor icing issues as the rain arrives. At this point, think the warm advection will win out, keeping surface temperatures above freezing prior to the onset of rain. The upper level wave will exit by late Saturday morning, as a midwest ridge quickly builds.
848 PM EST Fri Dec 23 2016 High pressure slides offshore to our south tonight.
Soundings across the Nebraska Panhandle on Saturday night suggest patchy fog/freezing drizzle may be possible, so added that to the grids.
The higher amounts are likely to be focused over far southeast MO/wrn KY.
High pressure near the Mid-Atlantic coast will continue to push offshore into tonight with low level easterly winds veering to the southeast late. Easterly winds up to 10-15 knots will veer to the southeast late tonight as high pressure near the Mid-Atlantic coast shifts farther offshore.
Winds then shift to more of a southerly direction tomorrow as the lee side trough strengthens. Highs tomorrow are expected to reach into the lower 50s to around 50 degrees.
A weak trough triggering this activity is embedded in zonal westerly flow and will quickly move east ending our rain chances for now. A much deeper trough will move into the Great Basin from the eastern Pacific this weekend causing west winds to increase once again.
A cold upper trough will pass the area on Saturday, with a few lingering snow showers or flurries. This pattern will continue into the evening as temperatures remain around freezing. An upper trough over the area will exit the region on Christmas Day, and upper heights will rise. The low level air mass will still be cold, with highs remaining mostly in the 30s.
1043 PM EST Fri Dec 23 2016 High pressure will move offshore this evening. A weak cold front will move across the region Saturday afternoon. High pressure returns for Christmas Day.
The HRRR continues to suggest the lowest visibilities will be just southeast of the I-44 corridor. In addition, many of these locations have forecast low temperatures near or even cooler than current dew points. On Christmas Day, a negatively tilted trough will move northeast from the southern and central Rockies.
648 PM CST Fri Dec 23 2016 Shallow cool air associated with a Canadian high pressure system is slipping south into North Dakota. A vigorous short wave trough just off the southern California coast is seen on the water vapor imagery loops. A 140kt jet is depicted by model data moving south on the western side of the trough. This jet streak will round the base of the trough tonight and swing northeast toward the northern plains Saturday.
And, monitoring the southward moving backdoor cold front now at least half way through North Dakota. The parent low over Ontario has a cold front spread across far northwestern MN and across the northern half of SD. The main concerns this period will be fog nearing ABR from the west, and light freezing precipitation Saturday night. Expect a better chance of fog overnight, behind the cold front.
734 PM CST Fri Dec 23 2016 Band of snow has pushed east of the forecast area with weak trough working across the forecast area. Southeasterly flow develops throughout the day on Saturday ahead of the approaching trough to the west. As moisture pools ahead of the storm, would expect areas of freezing drizzle to develop but with the expected warming, the time frame where -fzra would occur looks to be brief. Am concerned a little with SD highway 14 corridor about the freezing drizzle holding on a little longer, but models continue to push warm air northward quickly ahead of the storm.
Winds are currently from the south behind a warm front, with warm and moist air advecting into the region ahead of an approaching cold front. Have adjusted overnight lows up a degree or two as warmer air continues to advect into the region under cloud cover. Surface analysis this afternoon places a warm front from western Oklahoma back through northeast Texas. Meanwhile, across the Mid-South a mid-level subtropical jet is bringing Pacific moisture into the Lower Mississippi Valley and a low level jet streak and southerly winds on the back side of high pressure advecting moisture up from the Gulf of Mexico. A warm front and a trailing cold front is expected to move across the Lower Mississippi Valley later tonight into Saturday morning.
639 PM EST Fri Dec 23 2016 Column is beginning to saturate as isentropic lift component picks up ahead of an approaching trough. Overall, QPF values should range between a half and three quarters of an inch before the cold frontal boundary sinks south and stalls Saturday. Deep southerly flow will overspread the region between strong upper ridge in the SE CONUS, and strong low pressure over the northern Plains and upper Midwest. The response in the low level winds will bring a stalled frontal boundary just to our south back north as a warm front through the day, and the warm sector continuing through the night.
506 PM EST Fri Dec 23 2016 High pressure slides offshore to our south tonight.
A much colder airmass will impact the region the next few days, behind a cold front which brought rainfall to the region this morning. An upper trough digging along the west coast continues to be the big weather-maker across the region.
This precipitation is associated with low/mid level isentropic upglide to the south of a shearing upper level short wave trough. With confidence on the high side for dense fog development, we have gone ahead with a Dense Fog Advisory for much of the area. This advisory may eventually need some expansion into south-central Missouri, however we tried to hit the higher confidence areas for now. Highs are a tough call as a lifting warm front and the possible clearing will both come into play. That lifting warm front and associated warm/moisture advection will then lead to lowering clouds and drizzle Saturday night. Christmas will then be a windy and mild day as a strong low pressure system moves northeast across the Plains.
In addition, many of these locations have forecast low temperatures near or even cooler than current dew points. On Christmas Day, a negatively tilted trough will move northeast from the southern and central Rockies.
Mid/upper level trough continues eastward over the upper Midwest and Great Lakes region the rest of today. The lift associated with the trough has exited the area allowing subsidence and dry air into the region. The clouds have cleared as a response, which has caused temperatures to be slightly warmer this afternoon. The trough will push a weak cold front into our this evening. Surface winds will become light and calm as weak surface ridging slides through. The low lying locations will have the greatest chances of fog. Also, if fog forms given the freezing temperatures ice may become an issue on untreated roads and elevated surfaces.
For tonight, temperatures will remain in the mid 60s to lower 70s, then climbing into the low to mid 80s on Saturday afternoon.
The ridge axis will bisect the CWA north to south around 06z overnight but rapidly breakdown east of the cwa by 18z Saturday as a deep trough digs into the Desert Southwest. The high pressure aloft overnight will provide for mostly clear skies and noticeably cooler temperatures as favorable radiational conditions are expected. The low temperature forecast overnight is a product of bc data with the previous forecast which supports teens for overnight lows. The southerly fetch will allow for rapid saturation of the lower troposphere late afternoon Saturday.
644 PM EST Fri Dec 23 2016 A low pressure system approaching from the plains will cause a mix of light rain and light snow to develop by this evening and continue into early Saturday morning.
501 PM EST Fri Dec 23 2016 Fast moving low pressure will bring showers to the region after midnight and Saturday morning. Heaviest rain amounts will line up just ahead of the main trough axis spreading southwest to northeast. It is conceivable that some locations near freezing could wet-bulb down to below freezing, creating some minor icing issues as the rain arrives. At this point, think the warm advection will win out, keeping surface temperatures above freezing prior to the onset of rain. The upper level wave will exit by late Saturday morning, as a midwest ridge quickly builds.
A cold front and upper level trough will shift east over the forecast area Saturday with snow ending over southeast Oregon Saturday afternoon and decreasing over southwest Idaho Saturday night.
Surface analysis this afternoon places a warm front from western Oklahoma back through northeast Texas. Meanwhile, across the Mid-South a mid-level subtropical jet is bringing Pacific moisture into the Lower Mississippi Valley and a low level jet streak and southerly winds on the back side of high pressure advecting moisture up from the Gulf of Mexico. A warm front and a trailing cold front is expected to move across the Lower Mississippi Valley later tonight into Saturday morning.
With the cooler moist air spreading across the area.
615 PM EST Fri Dec 23 2016 A low pressure system will result in unsettled weather this Christmas weekend.
With the primary large scale ascent and deeper warm advection staying northwest of the forecast area, have kept rain chances on the low side, but areas northwest of Greenville to Grenada could see a few downpours tonight into Saturday.
Rain chances will then diminish Saturday afternoon after the passage of the cold front. A spotty rain shower or drizzle cannot be ruled out on Christmas, as warmer air begins to filter into the Ohio Valley.
919 PM EST Fri Dec 23 2016 High pressure will move offshore this evening. A weak cold front will move across the region Saturday afternoon. High pressure returns for Christmas Day.
910 PM EST Fri Dec 23 2016 Fast moving low pressure will bring showers to the region after midnight and Saturday morning. An open upper-level trough streaming through the Great Lakes is pulling Gulf moisture northward. Surface observations around the area are hanging in the mid to upper 30s with some creeping down to near-freezing north of I-80 and into Garrett County MD. It is conceivable that some of these cold pockets could hold at or just below freezing until the onset of the heavier rain. Heaviest rain amounts will line up just ahead of the main trough axis spreading southwest to northeast. The upper level wave will exit by late Saturday morning, as a midwest ridge quickly builds.
Once the low ceilings develop, improvement, for the remainder of the forecast period, is not likely.
A dryline/cold front trailing south into Oklahoma will trigger at least a broken line of showers and perhaps an isolated thunderstorm.
Cold front to approach our area but not until late tonight. On Saturday, the aforementioned boundary will come close to entering our northwest areas before stalling out and then lifting back to the north as a warm front. On Saturday night, upper level ridging will develop and with the front lifting northward, pops will decrease to just a low chance of light showers.
This light drizzle/freezing drizzle activity will continue east and taper off through the evening hours. Overall forecast remains on track with snow exiting this evening and then perhaps a brief window for drizzle/freezing drizzle, but overall confidence in any freezing drizzle is low. Behind this system, brief ridging works into the region tonight into Saturday with very light near surface flow.
718 PM EST Fri Dec 23 2016 High pressure will be off the Mid-Atlantic Coast tonight and Saturday and establish an onshore flow into the forecast area. A weakening cold front will be just northwest of the area Saturday. The front will dissipate and high pressure will ridge into the region from the north Christmas Day. Continued to indicate a slight chance in the northern portion of the forecast area overnight night as this area is a little further from the strong upper ridging. Increased cloud cover and a 20 knot low level jet will promote overnight lows in the low/mid 40s.
Seeing that today's highs already reached the mid 80s, pushed the highs for Saturday into the mid 80s as well, with upper 70s in the northwest ranchlands where cloud cover may hang on longer into the afternoon.
Water temps are a bit warmer than last night so fog threat along the coast is also less certain. /ISSUED 340 PM CST Fri Dec 23 2016/ The warm front was well to the north this afternoon.
Chattanooga Airport, TN 46 56 48 70 / 30 60 30 10 Knoxville McGhee Tyson Airport, TN 42 55 47 67 / 60 90 30 20 Oak Ridge, TN 43 53 45 66 / 80 90 30 20 Tri Cities Airport, TN 37 54 44 63 / 90 90 30 10 TN.
Showers and isolated thunderstorms are expected with the heaviest of the rainfall over central and southern sections, in the vicinity of a stalled out warm front.
1210 PM MDT TUE AUG 30 2016 Upper ridging continues to dominate the weather pattern across the Northern Plains. Upper ridging continues across the High Plains today as the main flow persists across Canada. however with the ridge in place there is extremely weak shear. Upper ridging will increase in amplitude while remaining stationary across the region as an upper trough moves into the West Coast.
Currently surface and upper high pressure ridging dominates the weather pattern, while surface winds remain light and variable or a light east flow, and surface dewpoint temperatures are from the upper 60s to mid 70s.
Strong upper ridge still parked over the Ohio Valley will keep temps several degrees above normal to close out the month of August. Ridge axis is almost directly overhead today, keeping convective temps above 90F. Max temps this afternoon will reach the lower 90s with the heat index again pushing 100, but still well short of advisory criteria. By early Wednesday an upper trof axis will be diving SE out of the Upper Midwest, with convection focused behind a cold front.
234 PM CDT TUE AUG 30 2016 The weak trough aloft has settled into the mid Missouri River valley, with ample environmental tropical moisture in place across the southern half of the forecast area. The trough will drift southward tonight into early Wednesday, with drier higher pressure building in from the north.
An upper-level ridge remains anchored over Indiana. This along with the weak upper low in Georgia will bring in dry air from the northeast, thus limiting convection more so today than yesterday. Similar to yesterday, models hint a very weak piece of upper level energy rounding the ridge and skirting along the southeast of Central AL, near the best 1000mb-500mb moisture as well. Due to the reduced rain chances, temps will increase slightly, but still expected to remain in the low 90s. Meanwhile to our north a trough will continue to dig southward toward the area. This trough will be the main reason the tropical system will curl back to Florida. As the trough slides down, can not rule out an isolated shower or storm across the far northern counties as well.
Ridging influences surface and aloft will continue through Wednesday across the mid state, as a summertime pattern continues, with a slight chance of light to moderate showers and thunderstorms across the mid state by Wed afternoon as a surface front approaches.
110 PM EDT TUE AUG 30 2016 High pressure over the eastern Great Lakes will move off the east coast. A cold front from the upper midwest will sag across the area on Wednesday.
404 PM EDT TUE AUG 30 2016 A cold front will move south across the area late tonight and Wednesday followed by a secondary cold front Wednesday night.
A cold front will bring scattered showers and thunderstorms later Wednesday and Wednesday night. A cooler pattern will follow for the remainder of the week. Fries The main event will be the cold frontal passage late Wednesday and Wednesday night. However, we cannot rule out some at least briefly heavier rainfall rates, given the high moisture content and sufficient warm cloud depths.
405 PM EDT TUE AUG 30 2016 High pressure moves offshore tonight.
For today it appears that main chances for precipitation will once again be across our central Georgia counties where better moisture and closer proximity to the upper low remain. Wednesday is a bit trickier with weak cold front approaching the northern border potentially increasing the chances for some isolated to scattered convection across the north and the uncertainty of the path and speed of the gulf system and any influence it may exert across the southern reaches of the forecast area.
High pressure in the wake of this system will provide cooler and drier conditions for the area late in the week and into the weekend. May see a bit of a lull before potential increases again late as the cold front moves into the area. Main focus in the short term will be Wednesday as the cold front moves through the area. High pressure will move into the area in the wake of the front, which will move significantly drier air into the region and bring a break from the recent oppressive heat and humidity.
206 PM EDT TUE AUG 30 2016 High pressure centered over the Eastern Great Lakes is forecast to keep dry weather over the area today. The threat of showers and thunderstorms will return Wednesday with a cold front.
Otherwise, the boundary will work to clear the CWA this evening, and with loss of diurnal support and weak mid-level trough shearing southward, any precipitation chances will end very early this evening. Wednesday a very pleasant late summer day with ridging building surface and aloft.
211 PM MST TUE AUG 30 2016 Strong high pressure in the eastern Pacific will result in above normal temperatures the next few days, particularly across southeastern California.
The ridge axis remains in place today bringing another day of hot weather. We will finally begin to see a shift in the pattern tomorrow as a trough begins to dig into the upper midwest. A cold front will push through the lower Ohio Valley Wednesday bringing with it scattered showers and storms. For tomorrow night, the cooler air will start to filter in, but the much drier air will lag the front a bit.
The low center is forecast to move towards Apalachee Bay on Thu with increasing low level southerly flow maintaining high moisture especially across the north. Widespread heavy rain should accompany the closest approach of the tropical cyclone on Thu north of Orlando but models are showing a trend toward a leftward shift in the track which would keep the heaviest rains north of Lake/Volusia.
139 PM EDT TUE AUG 30 2016 High pressure will keep it warmer than normal and mainly dry into Wednesday.
An upper ridge will continue to build along into the northern and Canadian plains over the next few days. As the ridge amplifies the hot desert air-mass will filter north through the local area and into Canada.
A broad upper level low and trough is located in the eastern Pacific. Disturbances rotating around the low will bring moisture and lift.
320 PM CDT TUE AUG 30 2016 Rain chances will continue through tomorrow as the weak trough to our west slowly fills and upper-level jet energy starts to shift off to the northeast of the forecast area. The Rolling Plains may see temps slightly warmer as coverage of precipitation in the models is a bit less than in previous days.
Small hail in the high elevations will remain a threat as well as gusty outflow winds. High pressure becomes more dominant over the region by Wednesday as a digging trough in the west forces the ridge to amplify over the northern Rockies. The Pacific low pressure system will continue to shift east on Thu and will move over British Columbia and Washington Thu night and Fri. The associated trough will strengthen along the West Coast with a south-southwest flow developing over our forecast area by early Thu. In addition, the GFS indicates cooler temperatures will occur as cooler air filters in on Sat, and a cold front passes over the area on Sun.
Coverage of thunderstorms will increase even further on Wednesday as a cold front slides south through the Ozarks. High temperatures will be cooler with the passing front and expected coverage of thunderstorms. Highs will generally be in the lower to middle 80s. Fabulous late summer weather is then expected to end the week as Canadian high pressure builds into the region. Early tomorrow morning sites should expect lower visibility with thunderstorms coming in from the northwest with a cold front that will be moving through the area.
Another mostly sunny day is in store for Wednesday with the potential again for a few isolated showers and thunderstorms to develop across the higher terrain during the afternoon and early evening hours. A cold front will be located across the Ohio Valley at the start of the period, moving southeast.
245 PM CDT TUE AUG 30 2016 Upper level high pressure over our region that has been bringing all of the hot and humid conditions lately will finally be forced sw into the Southern Plains during the short term as a mid lvl short wave digs southeast from the Midwest region on Wednesday.
Expecting that this trend will continue through Wednesday, as the upper ridge drifts wswwd across OK and into TX.
An upper level ridge of high pressure has become centered over northern portions of the Mid South. /issued 234 AM CDT TUE AUG 30 2016/ A strong upper ridge will persist over the Mid-South today. With the ridge being centered over the area, expect convection to be suppressed for the most part. The upper ridge will begin to retreat to the south and west tonight. This will allow a cold front to approach from the north on Wednesday.
314 PM EDT TUE AUG 30 2016 Warm and muggy conditions will prevail into Wednesday with a chance for a shower or thunderstorm into this evening and again Wednesday as a cold front moves into the region. Cooler and much less humid air will filter in into the weekend. Lows tonight will be in the lower 70s with highs Wednesday in the middle 70s to lower 80s. After that cold front will begin to approach and slowly drift southeast during the day Wednesday.