Aikyam-Lab/Synoptic-Bench huggingface dataset:
900 AM EDT Thu May 21 2020 Rain chances return today and Friday with crossing low pressure. At the surface and low- levels, high pressure is centered off the northeast coast. This has allowed for a rather persistent moisture stream in the residual warm conveyor belt of the meandering Ohio/Tennessee Valley low pressure. Precipitation spreading along a surface/mid-level trough and within this moisture stream will inch northeastward over the next several hours as the stacked low drifts northward. The low should continue its northward track tonight, before turning east across the Ohio Valley region Friday as it advances across the northwest periphery of the high. A few afternoon and evening thunderstorms are also possible Friday as minimal destabilization occurs, and the low crosses the region.
A clear sky prevailed across the area this morning with 2 am temperatures running 2 to 10 degrees, depending on location, cooler than 24 hours ago. After a beautiful day yesterday, highs will be 2 to 7 degrees warmer today but still running 2 to 6 degrees below normal.
DVL region is a bit tougher but area is not wide too and moving NNE so may well break out of the low clouds there too into some mid clouds. Sun - Wed Upper level low forecast to move across the area Sun.
Lowered highs to the upper 60s/low 70s across southern and western Minnesota where the cloud cover looks to remain most widespread this afternoon, and kept highs in the low to mid 70s across eastern Minnesota and west-central Wisconsin where clearing looks more possible.
Expect the lower conditions to persist in these areas overnight and Thursday along with some showers, but with some improvement to VFR at times as well. A closed upper level low is expected to produce three weak fronts through friday morning as it tracks through Washington and Oregon. Elsewhere in southwest Oregon and Northern California impacts include, cooler temperatures, increased low and mid level cloud cover, and breezy to windy west to northwest winds.
427 AM CDT Thu May 21 2020 The synoptic set-up starts out with the area sandwiched between a mid-level low over northern Montana/southern Alberta and cut-off low pressure over the southeastern CONUS. Blocking high pressure over Great Lakes region to the northeast CONUS keeps things in place for most of the period.
553 AM CDT Thu May 21 2020 A slow moving, cut-off upper level low over north central TN will move north-northwestward into southern IN this evening, then northeastward through southern OH on Friday as a negatively tilted upper level trough moves into eastern Nebraska and western IA. There will be patchy drizzle this morning with isolated light showers this afternoon into the evening, mainly across southeast MO and southwest IL, west of the upper low.
There is some mid level cold advection in the trough axis, and that will steepen lapse rates. For tonight, some evening convection may linger over the southern portions of the forecast area until about midnight with the upper level trough moving across. An upper trough over the Pacific Northwest will dig down into the Great Basin then into southwestern Wyoming by Friday night. Enough moisture out over the eastern plains and lift from the incoming trough will likely allow for isolated thunderstorms Friday evening.
628 AM CDT Thu May 21 2020 High pressure remains overhead today, but a quasi-stationary front will make a slow progression eastward over the next several days.
Clouds will then increase early Friday as the low pressure system that brought us all our rain pivots east through southern Ohio.
Strong to Isolated Severe Storms Possible Later This Afternoon Ridge axis will remain just south of the area today, but low level south to southwest flow will remain weak enough for the east coast sea breeze to develop and move inland this afternoon. Strong surface heating and slower westward movement of the sea breeze from the weak, but opposing offshore flow, will allow highs to reach the low to mid 90s, with sfc dewpoints in the mid 60s-low 70s this afternoon.
1027 AM EDT Thu May 21 2020 A ridge axis stretches west across South Florida. Water vapor imagery highlights a cut-off cyclone over TN, although the southern flank of this system extends to the southern Gulf of Mexico. The 12Z KKEY RAOB sampled southeast to south winds from the SFC through 600 mb, highlighting the mean layer lower tropospheric ridging. Above that, westerlies associated with the cyclone are dry and lapse rates are steep. Highs will easily reach the upper 80s, with a few of the larger islands climbing into the lower 90s. A western Atlantic ridge axis stretched across South Florida will lift northward into Central Florida over the next couple of days. As the ridge moves northward, easterly breezes will freshen.
614 AM CDT Thu May 21 2020 An upper level Rex blocking pattern continues east of the area which was keeping a closed low over the TN/OH valley region and most of our CWA within a cyclonic flow pattern northwest of the low. Some low cloud cover still affecting much of the eastern CWA because of the proximity of the low. Temperatures have also been held in check due to the low. For today, the cut-off upper low will slowly drift northeast, but not far during the day.
The low pressure system that has brought copious amounts of rainfall to the region will begin to move northeastward into Canada.
517 AM MDT Thu May 21 2020 The upper low over Montana will move off to the north today. At the surface, a N-S oriented trough/front will be located over the eastern part of the forecast area. Deep moisture and instability to the east of the trough will create a chance of showers and thunderstorms over parts of south central South Dakota. Dry weather is expected over the rest of the forecast area due to southwesterly surface winds and lower relative humidity to the west of the trough.
Much cooler conditions observed this morning with temperatures around freezing across the high valleys of Carbon and Albany counties. Although today will be cooler, models have trended slightly warmer compared to yesterday as weak ridging may redevelop late in the day across the Front Range. For Friday and early in the weekend, another strong Pacific upper level low will dig south on the backside of the main upper level low in Montana today. Friday will see a brief warming trend with highs in the 70s across the higher elevations over 6000 feet, with readings in the low 80s across far eastern Wyoming and the Nebraska panhandle.
Showers and isolated thunderstorms will linger across northern Utah behind an exiting low pressure system today. The next low pressure system moving south along the British Columbia coast will impact the Great Basin beginning Friday.
The upper low continues to spin around our area with the center over Sumner County right now. The upper low will wobble northward through the day with instability increasing.
Forecast confidence is medium to high: It should stay mainly dry through Friday night, as weak high pressure lingers over the Great Lakes. Persistent onshore winds should keep it cooler in the east.
Expect scattered to broken cloud cover over the area going into tonight as southeasterly flow brings in moisture from a nearly stationary low pressure system over the Ohio River valley Region.
329 PM EDT Thu May 21 2020 A closed upper low over Kentucky will track northeast over the Mid Atlantic States the next couple of days.
1236 PM CDT Thu May 21 2020 A slow moving, cut-off upper level low over north central TN will move north-northwestward into southern IN this evening, then northeastward through southern OH on Friday as a negatively tilted upper level trough moves into eastern Nebraska and western IA. There will be patchy drizzle this morning with isolated light showers this afternoon into the evening, mainly across southeast MO and southwest IL, west of the upper low.
Satellite WV imagery shows the cutoff upper low centered north of Nashville along the Middle TN/KY border. Areas of PV continue to rotate around the upper low with a PV max noted on 6. Highest PoPs will be across the Cumberland Plateau (near the upper low), and NE TN/SW VA (ahead of the slowly eastward progressing PV max). JB Chattanooga Airport, TN 59 81 64 86 66 / 40 60 30 50 10 Knoxville McGhee Tyson Airport, TN 59 77 62 84 65 / 40 60 40 50 20 Oak Ridge, TN 59 76 62 83 65 / 30 60 40 50 20 Tri Cities Airport, TN 54 74 59 80 60 / 30 70 40 40 10.
An upper level low is expected to move into the area tonight. Later tonight, the upper low will keep some showers and thunderstorms moving through the area during the night. Clouds should clear out behind the storms and expect temperatures to be a little cooler Friday night.
333 PM CDT Thu May 21 2020 The persistent, closed upper low over the OH Valley will finally begin to lift north tonight as the Rex Block weakens with the upper-level ridge over the Great Lakes shifting east. We'll continue to see a few showers through early evening, but the effects of the approaching trough will be felt overnight into early Friday. Lift will be enhanced by warm advection in the lower troposphere, resulting in scattered showers and thunderstorms after 06z and continuing into early Friday before diminishing from west to east around midday. A few of the CAMS indicate a second round of storms moving into the area during the afternoon, the remnants of an MCS that will develop across the High Plains this evening.
Additionally, could see some showers approach the Cumberland Valley late tonight into Friday morning as the upper low finally slides northeast toward Cincinnati, helping to usher in an uptick in low level winds. Warmer air pushing in Friday in the southern quadrant of the upper low will spell numerous showers with embedded thunderstorms across eastern Kentucky. Despite increasing 0-6 km shear values to 40-50 knots, instability looks to be on the low side, keeping any storms from becoming overly strong.
417 PM EDT Thu May 21 2020 A low pressure system moving through the Ohio Valley will bring increased cloudiness and rain to the area through Friday. Cut-off low pressure will begin to move northeastward and bring a line of light rain through the region.
335 PM CDT Thu May 21 2020 A warm front is progressing north across the region, ushering in very muggy air from the Gulf. As the afternoon progresses, this may need to be revisited as the dwpts in the SE are still in the lower 70s.
323 PM EDT Thu May 21 2020 High pressure will maintain dry and seasonably warm conditions across the North Country through the holiday weekend.
Tomorrow, another warm day is expected, with temperatures again expected to reach the low 90s.
255 PM EDT Thu May 21 2020 Broad high pressure along the Mid-Atlantic coast will continue to maintain fair and dry weather tonight. High pressure will then exit allowing low pressure to our south to introduce a few showers to our region Friday and Friday night. Low pressure to our south will begin to advance towards the Ohio Valley tonight.
354 PM CDT Thu May 21 2020 As of this afternoon, the pattern over the CONUS remains dominated by the closed upper low over the Ohio River Valley and a broad trough over the western US.
147 PM CDT Thu May 21 2020 High pressure remains overhead today, but a quasi-stationary front will make a slow progression eastward over the next several days.
Surface ridging extending across the Peninsula south of a stationary boundary situated across the northern Gulf Coast is responsible for west/southwest surface flow across the region this afternoon. Boundary will gradually shift north into the weekend allowing ridging to establish itself across the region with flow becoming more easterly. More established easterly flow Friday will result in shower/storm activity affecting areas closer to the coast during the afternoon with highs reaching the low/mid 90s.
209 PM EDT Thu May 21 2020 High pressure will maintain dry and seasonably warm conditions across the North Country through the holiday weekend.
1248 PM CDT Thu May 21 2020 Cigs have returned to VFR across most of the terminals early this afternoon, and this should remain the case except for portions of extreme NE TX/SE OK/Nrn sections of SW AR near and N of a warm front that has shifted N to just S of the Red River of NE TX to along the AR/LA line.
The low clouds were moving to the northwest, but were eroding on the leading edge due to abundant dry air across northern Wisconsin and much of Michigan. Once the sun sets this evening, the low clouds should advect into central and portions of northeast Wisconsin. There is some question on how far north the low clouds will make it, thus lower confidence in the cloud cover across the far north. High temperatures will be in the upper 60s to middle 70s, cooler near the bay and Lake Michigan.
/issued 957 AM CDT Thu May 21 2020/ The cut-off upper low continues to meander around the OH Valley this morning, providing northwest flow aloft across the Mid- South. The expansive upper level low is still centered over Middle Tennessee, with associated heavy cloud cover over much of the region. This low is expected to retrograde westward back into our area this afternoon. This activity will come to an end this evening as the upper low finally lifts northeastward out of the area. Expect highs to climb into the mid to upper 80s each day, with heat indices approaching the low to mid 90s.
150 PM EDT Thu May 21 2020 An upper low was near the Tennessee and Kentucky border early this morning.
Latest HRRR initiate these convective elements at 21 UTC along the cold front along the highway 25 corridor with organized elements reaching the highway 83 corridor by around 10 pm. Potential exists for thunderstorms to be ongoing early Friday morning across the eastern and especially south central Kansas counties as models show a mid level trough/weak pvu anomaly moving though the area with still conditionally unstable air.
However, another area of low pressure is moving into the Pacific Northwest, and will bring a return of showers and isolated thunderstorms this afternoon and evening. Another trough moving through the area on Friday will bring some higher elevation showers through the day.
The upper low bringing the rain chances the past few days is lifting northward and losing its hold across the area. Friday will be a return to southerly flow at the surface with weak ridging aloft and diurnally driven afternoon and early evening convection associated with the sea breeze circulation.
355 PM CDT Thu May 21 2020 High pressure to our east along with low pressure developing over the high plains will continue to produce moisture into the area from the south. Temperatures to remain on the warm side during this time frame with the warm air moving into the area, and afternoon highs should get back into the low 70s on Friday.
/Tonight through Thursday/ The cutoff low pressure that has brought us cloudy misery this week is over Kentucky with an upstream trough over the Rockies that is trying to push eastward toward Iowa. 5 inches to be drawn northward ahead of the Rockies' trough. This will bring increasing thunderstorm chances from southwest into northeast Iowa through the day with the highest chances over central Iowa late afternoon into Friday night.
245 PM CDT Thu May 21 2020 The upper low continues to move northward this afternoon with the center northwest of Bowling Green. Scattered showers dot the radar with the highest concentration north of I-40. The upper low will finally get out of our lives tomorrow as it lifts into Ohio and Pennsylvania but leaves us in an area of 40-50 kt mid level winds during the morning and first part of the afternoon. Models show storms ongoing along a warm front that will lift into our area during the morning. Mid level lapse rates will still be steep in the wake of the upper low with models showing values around 7 C/km. Upper level ridging will be building in from the west through the afternoon which will help trim back PoPs during that time frame.
326 PM CDT Thu May 21 2020 Low pressure across Alberta and western Saskatchewan will slowly drift north tonight and Friday leaving a weak pressure gradient across the region.
Upper air analysis continue to show the upper level low over Kentucky finally lifting north and northeast.
The low will finally work its way into Ohio tonight, drying things out overnight. A warm front will cross the area Friday night, leaving overnight lows elevated in the mid 60s.
319 PM EDT Thu May 21 2020 A ridge axis stretches west across South Florida. Water vapor imagery highlights a cut-off cyclone over TN/KY, although the southern flank of this system extends to the southeastern Gulf of Mexico. The 12Z KKEY RAOB sampled southeast to south winds from the SFC through 600 mb, highlighting the mean-layer lower tropospheric ridging. Above 600 mb, westerlies associated with the cyclone are dry and lapse rates are steep. As such, the lower tropospheric ridging will consolidate over the southeastern US as the mid-upper low exits the Northeast. Although there are no signs of an inverted trough forming along the southern flank of the subtropical high, this pattern would favor occasional kinks in the ridge.
122 PM EDT Thu May 21 2020 A low pressure system moving through the Ohio Valley will bring increased cloudiness and rain to the area through Friday. At the surface and low- levels, high pressure is centered off the northeast coast. This has allowed for a rather persistent moisture stream in the residual warm conveyor belt of the meandering Ohio/Tennessee Valley low pressure. Precipitation spreading along a surface/mid-level trough and within this moisture stream will inch northeastward over the next several hours as the stacked low drifts northward.
Upper low near the Tn-Ky border will drift ne into the Ohio Valley tonight and Friday which will lift the frontal boundary into central Ga. A ridge will start to build over the se which will result in hotter temperatures on Friday with scattered afternoon/evening storms expected to develop near the inland moving seabreezes. Temperatures should reach the low/mid 90s Friday afternoon over inland areas.
An upper level Rex blocking pattern continues east of the area which was keeping a closed low over the TN/OH valley region and most of our CWA within a cyclonic flow pattern northwest of the low. Some low cloud cover still affecting much of the eastern CWA because of the proximity of the low. Temperatures have also been held in check due to the low. For today, the cut-off upper low will slowly drift northeast, but not far during the day.
A large upper level low centered over southern Kentucky will continue to lift northward through Friday. Meanwhile, a warm front will continue to lift northward this afternoon and evening and will be north of the area by tonight. Muggy conditions are otherwise expected as high temperatures are forecast to reach into the mid 80s to around 90 degrees over most locations, with dewpoints also remaining in the upper 60s to around 70 inland and in the lower to mid 70s closer to the coast during peak heating on Friday.
302 PM CDT Thu May 21 2020 RAP analysis placed an upper low over NW Kentucky, slightly north of where it was yesterday. On Friday, the nearly stationary upper low that brought 6+ days of low clouds to the Upper Mississippi Valley will begin to track into the Eastern U. Subsidence behind the low should lead to occasional breaks in the cloud cover, allowing highs to reach the lower 70s.
A deep area of low pressure is located over southeast Alberta drawing the winds through gaps and the terrain and across the Columbia Basin. The low will be at its lowest pressure through this evening before it starts to fill overnight and drift north. A few quick updates to the forecast includes increasing chance of rain starting early Friday morning and given the thick clouds northerly component, temperatures will stay on the lower side of the spectrum. Some guidance suggests Spokane won't even see the 50s Friday! For the time being, I updated the temperatures to drop them just a few degrees below the average guidance but not as low as the lowest guidance.
1154 AM MDT Thu May 21 2020 The upper low over Montana will move off to the north today. At the surface, a N-S oriented trough/front will be located over the eastern part of the forecast area. Deep moisture and instability to the east of the trough will create a chance of showers and thunderstorms over parts of south central South Dakota. Dry weather is expected over the rest of the forecast area due to southwesterly surface winds and lower relative humidity to the west of the trough.
As of this afternoon, the pattern over the CONUS remains dominated by the closed upper low over the Ohio River Valley and a broad trough over the western US.
RAP analysis placed an upper low over NW Kentucky, slightly north of where it was yesterday. On Friday, the nearly stationary upper low that brought 6+ days of low clouds to the Upper Mississippi Valley will begin to track into the Eastern U. Subsidence behind the low should lead to occasional breaks in the cloud cover, allowing highs to reach the lower 70s.
/GG/ A warm front is progressing north across the region, ushering in very muggy air from the Gulf. As the afternoon progresses, this may need to be revisited as the dwpts in the SE are still in the lower 70s.
CAMs are in good agreement with scattered showers and thunderstorms developing along a cold front tomorrow afternoon out west. Low pressure across Alberta and western Saskatchewan will slowly drift north tonight and Friday leaving a weak pressure gradient across the region.
The increased flow as brought in slightly higher mid 70s dew points and held temperatures up in the lower to mid 80s. While broad ridging is in place through the lower to mid levels, this evenings sounding indicated good CAPE and a 1. Short Term Update - Overall large scale lower to mid level ridging will continue to dominate Keys weather through the overnight period. Due to the ridging, the large scale environment is not encouraging convective activity. Ridging across Florida will maintain moderate east breezes across Florida Keys waters through the overnight period.
This is thanks to an upper low deepening and lifting north, keeping cyclonic flow in place over the region. Meanwhile, the upper low in Canada is shift eastward, dragging a cold front toward the region. The cold front appears to cross the western mountains by Friday afternoon. This cold FROntal PAssage also appears to coincide with favorable jet support, to further bolster shower development.
849 PM EDT Thu May 21 2020 A low pressure system moving through the Ohio Valley will bring increased cloudiness and rain to the area through Friday. Cut-off low pressure will begin to move northeastward and bring light rain through the region.
The upper low continues to move northward this afternoon with the center northwest of Bowling Green. Scattered showers dot the radar with the highest concentration north of I-40. The upper low will finally get out of our lives tomorrow as it lifts into Ohio and Pennsylvania but leaves us in an area of 40-50 kt mid level winds during the morning and first part of the afternoon. Models show storms ongoing along a warm front that will lift into our area during the morning. Mid level lapse rates will still be steep in the wake of the upper low with models showing values around 7 C/km. Upper level ridging will be building in from the west through the afternoon which will help trim back PoPs during that time frame.
628 PM CDT Thu May 21 2020 High pressure to our east along with low pressure developing over the high plains will continue to produce moisture into the area from the south. Temperatures to remain on the warm side during this time frame with the warm air moving into the area, and afternoon highs should get back into the low 70s on Friday.
/27/ Prior discussion below: A warm front is progressing north across the region, ushering in very muggy air from the Gulf. As the afternoon progresses, this may need to be revisited as the dwpts in the SE are still in the lower 70s.