Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/29/21

Area Forecast Discussion
National Weather Service Buffalo NY
1048 PM EDT Wed Jul 28 2021 .SYNOPSIS... High pressure across the region will maintain dry weather overnight. Then, a cold front will bring a chance for showers and thunderstorms Thursday, with some showers possible through Friday morning. Cooler weather will prevail Friday and Saturday as high pressure builds back across the area. && .NEAR TERM /THROUGH THURSDAY NIGHT/... High pressure crossing New England will provide fair weather overnight. Mostly clear skies at present will give way to mid and high clouds overnight spreading from west to east across the area. The coolest temperatures will be east of Lake Ontario, since this is where clear skies will last the longest. A mid level trough will dig across the region on Thursday, which will lead to increasing chances for showers and possibly a thunderstorm. A complex surface map, with majority of guidance bringing a convectively generated wave across Ohio which may clip part of the area Thursday morning. Majority of 12z high res guidance in the HREF suite and recent runs of the HRRR indicate remnants of this convection could follow H85-H3 thicknesses/edge of higher instability and move into southwest NYS by 12-13z/8-9 AM. Upscale convection has developed last couple hours over upper Lakes, but based on where most vigorous convection is attm, think stronger part of this line of storms may end up staying well to west of our area as it heads more south-southeast into better instability. However, showers and some embedded thunder are quickly spreading into eastern Upper Michigan and northern Lower Michigan. Starting to think this activity, at least in diminishing form, tied to leading shortwave may be what models show moving into western NY on Thursday morning. Radar trends overnight will hold key for how convection evolves over our region on Thursday. Though diurnal heating may support some instability with showers and possibly a thunderstorm on Thursday, more likely than not, any severe weather would remain to our south, with most recent SPC day2 outlook keeping the marginal risk just south of the NY/PA border. There may be some lake/upslope enhanced showers south of the lakes Thursday night. Otherwise, temperatures will average below normal with highs in the 70s on Thursday and lows in the mid 50s to around 60 on Thursday night. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... With 850mb temps dropping into the 6-7C range by Friday morning, some pesky lake effect/upslope rain showers will linger through the morning. Surface high pressure then builds into the central Great Lakes by afternoon, with associated subsidence bringing an end to any leftover showers and giving way for a dry afternoon. Though the summer sun will be shining, temperatures will be about 10 degrees below average, with highs around 70 across lower elevations and mid 60s for higher terrain. High pressure centered over the Ohio Valley and central Great Lakes Friday night will maintain dry conditions and northwest flow across our region. Some lake effect clouds may develop southeast of the lakes overnight, but low inversion heights should prevent any lake effect rain showers. Overnight temperatures will fall into the low to mid 50s across the lake plains and mid/upper 40s for the interior Southern Tier and North Country. The upper level pattern across North America will continue to amplify moving into the weekend, with a sharp ridge axis centered on the Rockies and an unseasonably deep downstream longwave trough in eastern North America. This will keep temperatures below average over the weekend. High pressure shifts eastward across NY/PA Saturday, maintaining dry weather through the day. Rain chances increase from northwest to southeast Saturday night as a shortwave rounds the base of the longwave trough, bringing with it an area of surface low pressure across the Great Lakes and New England. Extra cloud cover late Saturday night will help moderate overnight temperatures some, with lows in the low 60s and upper 50s across the Lake Plains, with low to mid 50s elsewhere. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Strong consensus that vigorous shortwave will drop across Lower Great Lakes on Sunday. Have bumped pops to high likely for showers and possible thunderstorms...very unsettled to end the weekend. Temps to struggle to get out of the 60s. Showers wind down in coverage Sunday night as shortwave exits across srn New England. While leftover showers will be possible across the North Country early Monday...large sfc high should promote fair dry weather Monday through Wednesday. Temps will slowly moderate through the period. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... High pressure will provide mainly VFR flight conditions overnight. Mid-level clouds will move in which will diminish the potential for fog across the Southern Tier. Showers will spread into the area Thursday morning, with possibly a thunderstorm. Increasing moisture will lead to lowering cigs with MVFR possible at KJHW by Thursday morning. Increasing chances for showers and possibly a thunderstorm Thursday afternoon, with MVFR cigs. Outlook... Thursday night...lowering cigs with IFR/MVFR restrictions. Friday...MVFR/VFR. A chance of showers with lingering clouds south of the lakes. Saturday...VFR. Sunday...MVFR. Showers likely. Monday...VFR. && .MARINE... SCA conditions not expected until Thursday night into Friday, due to the passage of another cold front. Lake temp/850mb delta Ts increase to 15C late Friday and Friday night, but relatively low equilibrium level suggest a low but non-zero risk for waterspouts during that time period. Confidence too low to include in the forecast for now. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Apffel NEAR TERM...Apffel/JLA SHORT TERM...Hitchcock/PP LONG TERM...RSH AVIATION...Apffel MARINE...Apffel
Area Forecast Discussion
National Weather Service Quad Cities IA IL
559 PM CDT Wed Jul 28 2021 ...00z AVIATION UPDATE... .SYNOPSIS... Issued at 235 PM CDT Wed Jul 28 2021 Very warm and humid conditions were observed early this afternoon. Well advertised heat has been verifying, with heat indices above 100 degrees at most locations. Dewpoints were in the middle to upper 70s, with a few AWOS sites which are known to have a wet bias with dewpoints reporting lower 80s. High level clouds may have dampened the heat potential some across the north, but it is still very hot outside. Several strong thunderstorms developed along a persistent 850-750mb mid-level boundary over northwest and northern IL this morning, some of which produced small hail, frequent lightning, and heavy downpours in Whiteside, Henry, and Bureau counties in IL. As of 2 pm, the warm temperatures aloft have kept a lid on any convection over most of the CWA. However, starting to see some Cu fields to develop close to our area on visible satellite. && .SHORT TERM...(This Evening through Thursday) ISSUED AT 235 PM CDT Wed Jul 28 2021 Forecast focus in the near term is on the heat. Will continue the heat advisory through 10 pm tonight across our northern counties and maintain the other areas through 8pm Thursday. Dewpoints will remain in the 70s through the overnight hours, keeping heat index values above 75 degrees, making for a rather uncomfortable night outside. Attention then turns to the evolution of severe storms across MN/WI this evening. Most model guidance now keeps this activity to the northeast of our CWA, so am expecting a quiet night through midnight if not later. Kept some slight chance PoPs over our far northeast counties to account for any outflow boundary making its way into our area early Thursday. Forecast soundings and RAP severe progs depict substantial CAPE values in the 1800-2000 J/Kg range, 45kts of 0-6 km shear, and PWs approaching 2" so any storm that does reach our area, will bring a threat of damaging wind and heavy rain. Overnight lows will only drop in the low to mid 70s. Thursday...a weak cold front will track through the CWA between 10- 16z before stalling out near the IA/MO border. Winds will shift to the north and bring a nice breeze to dampen the heat some, especially across the north. Convergence along this front is really weak, so anticipating little if any storm development until the afternoon hours in our southern third of the CWA. This is also where the heat/instability will build through the day and where there is a marginal risk for severe weather per SPC Day 2 outlook. Dewpoints will once again reach the low to mid 70s along and south of I-80 and combined with temperatures rising into the lower 90s, will result in heat index values above 100 degrees in the afternoon. Be sure to take frequent breaks and stay hydrated when working outside. Highs will be a few degrees cooler than today, with readings in the upper 80s north and lower 90s south. .LONG TERM...(Thursday Night through Wednesday) ISSUED AT 235 PM CDT Wed Jul 28 2021 Key Messages: 1) Warm and quiet weather continues through the beginning of the period, with potential for showers and storms returning Saturday. 2) Ridge builds in the west, putting us in a strong northerly flow, resulting in much cooler temperatures than we have seen as of late. Friday Through Sunday... Ridge in the west stays in place and continues to build through Sunday, leaving us in an upper level northwest flow regime. Winds as we get closer to the surface are generally from the west, shifting to a low level northerly wind on Saturday. This will help to keep the humidity a little lower than we have seen as of late, with dewpoint temperatures in the mid to upper 60s. Latest guidance continues to introduce a weak wave moving through Saturday evening and into Sunday, bringing a surface cold front through. Where confidence is lacking is the timing (slightly) and the overall coverage of precipitation, with latest trends pushing chances a little farther north. While precipitation is possible, widespread heavy rainfall isn`t expected at this time. The southern parts of our forecast area have been the targeted area for best chances to see precipitation over the last few forecast runs, which continues to be seen. Temperatures will be near normal at the start of the period, trending slightly below normal through the remainder of the weekend, especially after frontal passage. This will bring much needed relief to the area, with daytime temperatures in the upper 70s and low 80s and nighttime temperatures in the 50s and 60s. Next Week... The building ridge will hold strong through the first part of next week, leaving us in a northerly flow. This, coupled with the post- frontal airmass, will lead to a pleasant start to the week. Temperatures will feel much cooler than they have been, with widespread 70s and low 80s and dewpoint temperatures may also be in the 50s for some. This will continue through Tuesday. Wednesday, long term guidance indicates that the ridge will begin to slowly break down, but a newly developed cut off upper low will aid in keeping us in a relatively light northerly flow aloft. While that is the case, low level return flow will also commence. This will lead to increasing moisture and temperatures through the area. With the gyrating low to our east and increasing moisture and temperatures, we may see some chances for isolated to scattered showers to storms for the second half of next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) ISSUED AT 558 PM CDT Wed Jul 28 2021 VFR conditions will prevail for all terminals for this TAF period. A cold front is progged to move from north to south across the area late tonight and Thursday, which will result in a gradual wind shift from southwest to northwest. A low-level jet is forecast to develop ahead of the front just ahead of the front, which will result in a brief period of LLWS for KCID, KDBQ and KMLI Thursday morning. A scattered shower or storm will also be possible ahead of the front late tonight, but confidence is low as guidance is not in good agreement of impacts to the terminals. Have left mention out at this time, but this will be monitored for future TAFs. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Heat Advisory until 10 PM CDT this evening for Benton-Buchanan- Clinton-Delaware-Dubuque-Jackson-Jones-Linn. Heat Advisory until 8 PM CDT Thursday for Cedar-Des Moines-Henry IA-Iowa-Jefferson-Johnson-Keokuk-Lee-Louisa-Muscatine-Scott- Van Buren-Washington. IL...Heat Advisory until 10 PM CDT this evening for Bureau-Carroll-Jo Daviess-Putnam-Stephenson-Whiteside. Heat Advisory until 8 PM CDT Thursday for Hancock-Henderson- Henry IL-McDonough-Mercer-Rock Island-Warren. MO...Heat Advisory until 8 PM CDT Thursday for Clark-Scotland. && $$ SYNOPSIS...Gross SHORT TERM...Gross LONG TERM...Gunkel AVIATION...Speck
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
605 PM MDT Wed Jul 28 2021 .AVIATION...00Z TAF CYCLE VFR conditions are expected across all TAFs sites with ceilings SCT-OVC100 SCT-OVC250. VIS may temporally reduce to less than 10SM at KELP and KTCS between 01 and 03Z due to showers and thunderstorms in area. The winds will be generally from the northeast to the southeast at both KELP and KLRU between 10 and 20KT with gust up 30KTS. However, the winds at KTCS and KDMN will be generally from the northwest to the southwest between 10 and 20KTS with gust up to 30KTS. Not expecting any TS across the KDMN and KLRU; however, there is a chance for TS across the rest of the sites before 04z. The rest of the period will be relatively quiet with no reduction in VIS on the runways. && .PREV DISCUSSION...236 PM MDT Wed Jul 28 2021... .SYNOPSIS... Active weather continues over the next seven days. Scattered showers and thunderstorms are expected over the mountains, and isolated storms over the lowlands. There will be less activity in the next few days, but coverage increases late this weekend and early next week. The reason will be the approach of a backdoor cold front that will push moisture towards the Borderland on Sunday night. The moisture remains through at least the middle of next week. Temperatures remain at or slightly below normal. && .DISCUSSION... .SHORT TERM...Tonight and Thursday... East flow aloft tonight with some embedded energy in addition to an influx of moisture will result in the potential for some light showers or tstorms across portions of the area. HRRR appears to show a boundary popping said convection right over the Rio Grande. As such, have low end pops, but not expecting anything of significant consequence. Similar conditions expected on Thursday, with above normal PW, especially out west. However, dewpoints will top out in the lower 50s during the afternoon it seems, fostering only modest CAPEs of ~500j/kg, to up to 1000j/kg across far western areas. As a result, terrain and west of the continental divide will be the focus, with isolated popcorn storms elsewhere across much of the lowlands. Area of enhancement will be across the Gila, with locally heavy rainfall the primary threat. There`s some ""mildly"" enhanced flow aloft across the northern portions of the CWA, so I suppose a stronger storm or two cannot be ruled out, especially in the Gila. Temperatures through the period will be be seasonable and winds light to mildly breezy, 10 to 20 mph with a few higher gusts in select areas as the east moving boundary moves through tonight. .LONG TERM...Friday through Tuesday Night... Elongated upper high tilted from NW to SE from the Front Range to the Gulf States persists on Friday. This orientation allows an inverted trough to ascend from Mexico towards Arizona. The deep core of the moisture plume appears to remain over AZ. Thus, we have another day with convection starting over area mountains with a few storms moving over the lowlands later in the afternoon and evening. This weekend, the upper high backtracks towards the Central Rockies. Usually this would mean warmer temperatures and drier weather. However, the decent moisture content across the area, precipitable water ~1.2 inches and sfc dewpoints between 45 to 55F will keep slightly below normal temperatures and wetter conditions. The environment will also be marginally unstable, so storm chances don`t go away. The main hazard with any storm will be periods of heavy rain. Areas where the ground is saturated from the rain over the past couple of weeks, may experience minor flooding. Early next week, the upper high remains over the Rockies. However, a new feature comes into the forecast. A backdoor cold front moves over on Sunday night into Monday morning. Temperatures further drop with the advection of colder air, but stay around 5 degrees below normal for early August. We get an additional push of moisture increasing PW up to 1.5 inches along with a more unstable environment, which will lead to greater coverage of storms. Furthermore, the upper high will keep moving to the southwest US, while an upper trough while an upper trough over by a Great Lakes slowly moves east. Thus, the subtropical plume of moisture tilts to the east advecting more moist air right over New Mexico and bringing more chances for storms through the middle of next week. Temperatures will be at or slightly below normal through the middle of next week too. .FIRE WEATHER... Typical monsoon through the Saturday (scattered mtn storms and isolated lowland), with isolated pockets of locally heavy rain across the Gila. An uptick in activity is possible Sunday into early next week as an east push brings in moisture. Temperatures remain either at or slightly below climate normals with light to mildly breezy winds, 5 to 15 mph, each afternoon outside of convection. Ventilation a mix of Good to Very Good through Saturday with min RH 30 to 50% mtns and 20 to 30% lowlands. && .PRELIMINARY POINT TEMPS/POPS... El Paso 74 92 73 93 / 20 20 20 0 Sierra Blanca 67 86 65 87 / 10 20 10 10 Las Cruces 69 91 68 92 / 20 20 20 0 Alamogordo 68 90 67 91 / 20 30 10 20 Cloudcroft 51 68 49 68 / 20 40 20 30 Truth or Consequences 68 90 68 90 / 30 30 30 10 Silver City 61 83 61 83 / 30 50 50 20 Deming 69 93 67 93 / 20 30 30 0 Lordsburg 69 91 67 91 / 20 40 40 20 West El Paso Metro 74 93 73 94 / 20 20 20 10 Dell City 67 91 67 92 / 10 10 10 10 Fort Hancock 72 94 70 95 / 20 20 10 10 Loma Linda 66 85 67 86 / 10 20 20 10 Fabens 72 93 71 93 / 10 20 20 0 Santa Teresa 72 91 69 92 / 20 20 20 0 White Sands HQ 70 90 70 91 / 20 20 20 10 Jornada Range 68 89 68 90 / 20 20 20 10 Hatch 69 91 68 91 / 20 30 30 0 Columbus 70 91 69 92 / 20 30 30 0 Orogrande 69 90 68 91 / 10 20 20 10 Mayhill 56 77 55 78 / 20 30 10 20 Mescalero 56 78 55 78 / 20 30 20 30 Timberon 54 76 53 77 / 20 30 10 20 Winston 58 82 57 82 / 30 40 40 20 Hillsboro 64 87 64 87 / 30 40 40 20 Spaceport 68 89 67 89 / 20 30 30 10 Lake Roberts 56 84 56 83 / 30 60 50 30 Hurley 62 86 62 87 / 20 40 40 20 Cliff 65 89 60 91 / 30 60 40 20 Mule Creek 61 86 62 86 / 20 70 50 30 Faywood 64 86 64 87 / 30 40 40 10 Animas 68 91 65 90 / 20 30 30 20 Hachita 68 89 65 90 / 20 30 30 10 Antelope Wells 67 90 65 90 / 30 30 30 20 Cloverdale 65 86 62 85 / 30 40 40 30 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$ 35-Delizio/29/36
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
637 PM CDT Wed Jul 28 2021 .AVIATION...00Z TAF Package Spotty shower activity continues over portions of the Southern Edwards Plateau and Hill Country region but should diminish over the next few hours as daytime heating wanes. Have kept mention of VCSH at DRT until 02Z for the activity. VFR conditions prevail otherwise at all sites through the TAF period. A few low clouds may develop overnight into early Thursday morning but areal coverage should remain limited to VFR standards. Outside of some mid-level cumulus tomorrow afternoon, development of some isolated showers along with perhaps a stray storm may be possible around AUS during the late afternoon. However, confidence is currently too low at this time of any flight impacts, to insert any mention of convection within the TAF package. Light east-southeasterly winds trend with near calm levels overnight along the I-35 sites. && .PREV DISCUSSION... /ISSUED 236 PM CDT Wed Jul 28 2021/ SHORT TERM (Today through Thursday)... Latest 500mb RAP analysis places an inverted trough over northeastern Mexico, with a notable spin on GOES 16 WV imagery.A 598dm Subtropical Ridge remains centered over north-central Kansas, acting to suppress convection. Despite this ridging, the aforementioned inverted trough will act to generate isolated showers and thunderstorms this afternoon and evening, especially over the Coastal Plains, northern Hill Country, and Southern Edwards Plateau. An shower or storm activity should quickly wane after 03Z from east to west, with another mild, muggy, and seasonable night in store. Thursday looks similar to today, but we`ll be on the backside of the inverted trough, and the Subtropical Ridge will slowly begin migrating further south yet again. This will act to further suppress convection, but we will still hold onto 20% PoPs as sea breeze influences will still be at play. As far as temperatures go, it will be slightly cooler today, as increased cloud cover in isolated showers and storms will keep temps slightly cooler, generally in the lower 90s north and mid to upper 90s south. Thursday will be slightly warmer and closer to normals with highs back in the mid to upper 90s areawide, with a few spots in the Rio Grande Plains getting near the century mark. LONG TERM (Thursday Night through Tuesday)... As ridging moves back in, rain shuts off for most of the area with the exception of some coastal sea breeze showers that may move inland. The weekend should be a mostly dy forecast with temperatures on the rise. Highs over the weekend to be at or just above normal. With the humidity, the heat index values become elevated. Practice heat safety if outdoors. By Sunday night, a cold front approaches from the north and should remain north of the area, however, would be the focus for some showers and thunderstorms in the afternoon beginning on Monday. For this package, have opted to keep POPs low until better agreement on how far south the front moves. Increased cloudiness and some weakness in the ridge should take temperatures down a few degrees early to mid week. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 77 96 76 95 76 / 10 20 - 20 0 Austin Bergstrom Intl Airport 76 95 75 95 75 / 10 20 - 20 0 New Braunfels Muni Airport 75 96 74 95 75 / 10 20 - 20 0 Burnet Muni Airport 75 94 75 95 75 / 10 20 - 20 0 Del Rio Intl Airport 77 99 78 99 78 / 20 - - - - Georgetown Muni Airport 76 95 75 95 76 / 10 20 - 20 0 Hondo Muni Airport 74 95 74 95 75 / - 10 - 20 - San Marcos Muni Airport 75 96 74 96 75 / 10 20 - 20 0 La Grange - Fayette Regional 77 96 77 95 77 / 10 20 - 30 0 San Antonio Intl Airport 75 94 76 94 76 / - 10 - 20 0 Stinson Muni Airport 77 96 77 96 77 / - 10 - 20 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term/Aviation...Brady Long-Term...Hampshire
Area Forecast Discussion
National Weather Service Grand Forks ND
905 PM CDT Wed Jul 28 2021 .UPDATE... Issued at 905 PM CDT Wed Jul 28 2021 The pesky storms finally exited Beltrami County Minnesota. The slowly falling dew points have now worked into areas north of a Baudette to Fargo to Valley City line. Temperatures have fallen across far southeast ND into adjacent areas of west central MN, but dew points there remain in the low 70s. However, dew points there should also begin a slow fall in the next few hours. UPDATE Issued at 627 PM CDT Wed Jul 28 2021 The front appears to have pushed through the FA now, but the high dew points still lag well behind the wind switch. However, relief is coming, as 50 dew points have entered the northern Red River Valley and portions of the Devils Lake region. The last of the early evening showers and storms are up around the Upper and Lower Red Lakes, moving quickly southeast. So expect within the next hour or so, the FA will be quiet again. With the drier air slowly filtering in and decreasing winds overnight, temperatures by morning will be a tad cooler than recently observed. && .SHORT TERM...(This afternoon through Thursday night) Issued at 322 PM CDT Wed Jul 28 2021 Isolated severe thunderstorms are still possible this afternoon, maybe into the early evening, though chances may be decreasing. Cold front continues to move south and east with a prefrontal trough still lingering over northwest and west central MN. Along/ahead of this axis high instability is in place, but stronger CAP due to stratus/convective debris from earlier activity today has limited further initiation. There is some clearing in immediately ahead of the front and may be allowing for better low level lapse rates/weakening of the CAP, however the window is slowly closing in our CWA as the this transitions eastward along wit the main axis of WAA/theta-E advection in MN. High sheer with veering profiles overlap this unstable air mass, so supercells would be possible within this environment if a stronger updraft is able to get going. Confidence is decreasing in initiation, but last few runs of HRRR still show isolated cells developing immediately ahead of the front in our east with short UH tracks for cells that do develop (we aren`t out of the woods yet but we are getting close). Impact messaging is in line with potential supercell development (2 inch or greater hail, winds to 75 mph, and isolated tornado). Rest of tonight-Thursday: Seasonable air mass returns to our CWA with northerly flow behind the cold front and dry/stable air. Once the flow shifts more to the north instead of northwest late tonight/Thursday morning smoke from Canadian fires may increase into northern MN and latest HRRR smoke model shows max surface smoke concentrations moving into north central and northwest Mn towards the RRV. So, while temps may be nice we may also see a return of air quality issues. .LONG TERM...(Friday through Wednesday) Issued at 322 PM CDT Wed Jul 28 2021 Friday into Saturday... Ridging aloft will continue to retreat south and westward throughout the long term period. As this occurs, we will look to transition into a northwesterly and then possibly meridional flow pattern aloft. One outcome of this pattern shift will be a return to more seasonable temperatures across the region for the end of the week and continuing into next week. A ridge riding shortwave trough is also expected to traverse the area late Friday into Saturday, and may introduce the potential for a few showers and thunderstorms to northwestern Minnesota. Otherwise, Saturday looks to remain quiet and dry with widespread high temperatures in the low to mid 80s. Sunday into next week... As the dominant area of ridging aloft continues to weaken, it looks like seasonable and quiet weather ahead to round out the weekend and move into next week. While a gradual warming trend will take hold as next week progresses, we should be able to stave off the 90s, at least through the early week period. The next shortwave is then progged to potentially arrive late Tuesday and bring with it the next chance for showers and thunderstorms. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 627 PM CDT Wed Jul 28 2021 North winds will stay gusty at KDVL/KGFK/KFAR for another hour or so, then they should decrease again. The lower level cloud cover should also decrease through the evening, leaving just some higher clouds or high level smoke. North winds within the valley (KFAR and KGFK) may get a little breezy again Thursday afternoon, but not like today. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...Godon SHORT TERM...DJR LONG TERM...Rick AVIATION...Godon
Area Forecast Discussion
National Weather Service Grand Rapids MI
1014 PM EDT Wed Jul 28 2021 LATEST UPDATE... Update .SYNOPSIS... Issued at 306 PM EDT Wed Jul 28 2021 -Damaging winds and heavy rainfall possible late tonight -Clearing out Thursday afternoon, dry Friday -Chance of storms Sat/sat ngt, then cool comfortable weather && .UPDATE... Issued at 1014 PM EDT Wed Jul 28 2021 I thought it good to say something about the timing of the storms tonight. There is an area of storms organizing over northern Wisconsin. The storms are expected to become better organized and move into our northwest CWA near Big Sable point near or after midnight. The storms will continue to move south and strengthen in response to a strengthening low level jet and mix layer capes near 2000 to 2500 j/kg. It seems the greatest threat for damaging winds would be south of Little Sable point and west of a line from Big Rapids to Jackson. There does seem to be the potential for wind gusts over 70 mph with some the bow echos expected to move into this area early Thursday morning. Also locally very heavy rain and localized flooding still seems to be an issue with this storms. So of our hi-res models are showing more than 2 inches of rain falling in less than 6 hours (really less than 3 hours). The heaviest rain would be in the same area as the strongest winds are possible. && .DISCUSSION...(This evening through next Wednesday) Issued at 800 PM EDT Wed Jul 28 2021 We remain on track for potentially destructive thunderstorm wind gusts late tonight with a heightened risk for tree and structural damage along with a large number of power outages. The latest SPC mesoanalysis suggests MLCAPE values of 2000-3000 J/kg even into the 03z-05z timeframe from MKG to GRR to BTL and points westward with little to no MLCIN. That will help allow the strongest thunderstorm winds to mix down to the surface with little to no resistance. Many of the last six hours or so of the HRRR runs have indicated pockets of 90+ mph wind gusts moving into our lakeshore counties with these storms tonight. Significant effective shear values of 50-60 kts are projected, helping aid or increase storm intensity. Isolated tornadoes or embedded QLCS tornadoes are still on the table as well, but the threat is likely dwarfed by the straight line wind damage risk given the areal scope and intensity that may be featured with these storms tonight. As for timing, we believe that after 11pm still looks on track for our NW region, then into the early morning hours for the majority of western, central, and southern Lower MI. There may also be an areal flood risk depending on possible redevelopment of shower and thunderstorm activity behind the main complex of storms. Some areas could get 2"-4" of rain if this occurs, leading to some ponding of water on roads prior to sunrise. Previous Discussion below... --Damaging winds and heavy rainfall possible late tonight-- Latest CAMs seem to have locked in on the farther north/northeast track of the most severe convection later tonight, still hinting at the possibility of a significant bow echo/potential derecho impacting much or parts of wrn Lwr MI. This may be a high impact severe weather event occurring while many folks will be sleeping, so messaging the possibility of damaging/destructive winds well beforehand is critical. Timing still looks to be after 11 pm, with potential for a large bow echo sweeping across Lk MI overnight. Also some potential for the warm advection wing ahead of the main line becoming active a couple hours beforehand. If that does occur, we could have some tornado potential with discrete cells since the warm front will be draped over the area. HRRR has 0-1km SRH of 150-200 m2/s2 with LCLs below 1km. A QLCS-type tornado threat may also develop/exist within the main line. Also of note, in terms of the straight line wind potential, HRRR still shows 70 kts at 3 km -- of potential descending rear inflow jet into the back of that line. So some isolated pockets of destructive 80+ mph winds seem plausible later tonight. As far as heavy rainfall/flooding concerns, some intense rainfall rates are likely as the strong/svr convection is coming through tonight, although the progressive nature of the MCS may limit the overall flooding risk. That said, some urban flooding - possibly worthy of areal flood advisories/warnings - may also be needed. --Clearing out Thursday afternoon, dry Friday-- While a trailing area of rain and embedded thunder may linger on the back side of the departing MCS Thursday morning, subsidence and drier air arriving from the north will bring decreasing clouds in the afternoon. Surface ridging building in on Friday brings a pleasantly cool day with sunshine. --Chance of storms Sat/sat ngt, then cool comfortable weather-- 12Z guidance little changed in showing the next frontal boundary dropping down from the north on Saturday with a good chance of showers and storms in the afternoon and night. Could see briefly warmer temps ahead of this feature on Saturday before another push of cooler/pleasant air comes down behind it for Sunday and beyond. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 737 PM EDT Wed Jul 28 2021 The greatest likelihood for IFR impacts at the terminals, coincident with significant thunderstorms and associated wind gusts potentially reaching 50 kts, is between the 05z-08z window. This window could still shift slightly either direction as storms are still developing as of this writing across northern WI. Kept ceilings above 1000 ft for now but trends may necessitate bringing a period of sub-1000 ft ceilings during this window. Additional shower or thunderstorm development is possible beyond the greatest severe weather threat, and that could linger toward 12z or a bit beyond. It is tough to pin down those specifics at this time and future amendments may be needed. A return to VFR is expected for most locations by late Thursday morning or early afternoon. && .MARINE... Issued at 306 PM EDT Wed Jul 28 2021 Small Craft Advisory/Beach Hazard Statement has been issued for late tonight through early Friday morning. While this is primarily for the stronger north flow behind the front, it is also intended to cover the severe wind gust threat tonight from thunderstorms. Also of some concern is the potential for a seiche/meteotsunami response to a fast moving Lk MI bow echo leading to notable/impactful water level fluctuations. However those specifics are awfully tough to nail down until confidence in a fast moving bow increase or become apparent. It is something that will need watched and could require a lakeshore flood advisory or warning at some point. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement from 2 AM EDT Thursday through Friday morning for MIZ037-043-050-056-064-071. LM...Small Craft Advisory from 2 AM Thursday to 8 AM EDT Friday for LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...Meade DISCUSSION...Hoving AVIATION...Hoving MARINE...Meade
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1025 PM CDT Wed Jul 28 2021 .UPDATE...917 PM CDT Current gridded forecast is in good shape, though storms are not moving quite as quickly at the moment. Earlier this evening rapid thunderstorm development occurred along and ahead of several boundaries in in northern Wisconsin, one being a warm front along the MN/WI border and a separate boundary just to the northwest of there. Lightning is now extensive across the entire line. Minneapolis was in the "true" warm sector earlier this evening extreme instability approaching 5000 J/Kg, 0-3 km shear of 37 kt and effective shear of 47 kt. There is a deep dry layer below the mid level moisture leading to substantial downdraft CAPE across the region. This instability/shear space is supportive of a hybrid bowing/supercell type environment. Therefore, damaging winds is going to be the main concern, but with the boundaries in place and some strong low level SRH (300-400 m2/s2 from Minneapolis to Lacrosse, WI) along with strong instability, large hail and even a few tornadoes are a concern in Wisconsin this evening. The Quad Cities sounding is equally juicy, high CAPE and lower level dry air to support storm maintenance southward in spite of some model capping and bit less shear. We are starting to see the signs of these storms starting to congeal into a line of storms, and this would be the most likely storm mode as they move southward along the instability gradient and motion vectors southeastward. Still given the degree of shear, some individual storm segments may continue, and thus some leading edge QLCS tornadoes remain a concern. SPC mesoanalysis does depict this DCAPE axis will spread southward toward the Wisconsin border tonight and into northern Illinois. A bit lower shear and some stronger capping into the local area still adds uncertainty as to the southern extent of the impact, but if things get organized the capping is not that strong and shear still sufficient to allow this storm complex to continue into the area tonight. Of note, 55 kt was just reported in Wausau, WI with these storms (62 mph) It appearing more likely that at least a portion of this complex will make it into our area, but weather it is as potent as it is now remains to be seen given the low level jet veering overnight tonight and some degree of mixed layer cap forecasted. The highest low level CAPE axis is still forecasted to increase with continued warm air advection along the core of the MDT/ENH risk areas from the SPC outlook, thus the mesovortex concern will continue into southern WI, getting close to our area. KMD && .MESOSCALE DISCUSSION... 1020 PM CDT The instability gradient now suggests that Wisconsin will be one of the highest areas of concern, and that a slightly further westward track to these storms may place a slightly bigger portion of our area in the concern area later tonight. There are still some low level stability concerns, but with the airmass still recovering ahead of the line of storms and still getting its act together, it is likely this complex will intensify and keep moving for a while. KMD && .SHORT TERM... 328 PM CDT Through Thursday night... The potential for a complex of severe thunderstorms capable of damaging wind gusts and maybe a tornado remains the forecast focus through tonight. Within this, substantial uncertainty remains, enough so to limit confidence on specific impacts within the CWA. The overall threat level remains highest within the level 3 (Enhanced) risk category per SPC Day 1 outlook given variance of solutions and conceptually how things may play out tonight. We are messaging a primary threat time of 12 AM to 5 AM CDT, possibly as early as 11 PM into the far northern CWA. Even if the main corridor of wind damage ends up to the north and east of the CWA, the forecast southeastward trajectory of the organized MCS potentially packing higher end wind gusts necessitates close monitoring of southern Lake Michigan water level monitoring for meteotsunami or seiche potential early Thursday morning. Finally, should the MCS become more west (or WNW) to east (or ESE) oriented, moisture and steering flow parameters support a localized flash flooding risk, though confidence was far too low for any Flash Flood Watch issuance. As of mid afternoon, the primary seasonably strong short-wave and mid-upper speed max resides on the far northeast periphery of the impressive mid-level ridge over the central Plains. This places it along/near the MN/Canada border. Pockets of elevated convection downstream of this wave have extended down to central Wisconsin, with current strongest convection north of DLH. In the immediate near-term, despite SPC (RAP) mesoanalysis indicating 3-4k J/kg of uncapped MLCAPE across the center of the CWA, it appears that the extensive cirrus blow from earlier and existing convection is limiting CI in the vicinity of remnant MCV near the MS River in northwest Illinois. Maintained slight chance PoPs through 00z given the very warm and oppressively humid (low-mid 70s Td) air mass, focused into northeast Illinois and northwest Indiana. To note, a few convective cells were developing as of this writing over interior northern Indiana. Should a stronger thunderstorm be able to form within the CWA, it would have a conditional downburst wind threat. Turning to the main event, later tonight-early Thursday, the lack of widespread strong and maturing convection upstream near the main short-wave path greatly limits predictability even at this late hour. Two of the most utilized CAMs, the HRRR and 3km NAMnest, for their 18z runs, have significantly divergent solutions. Conceptually, with the very sharply northwest flow pattern in place, storm motion to the southeast introduces the risk for propagation into the CWA if maturation of expected MCS occurs far enough south over Wisconsin. The forecast 850-300 mb thickness fields and forward propagating Corfidi vectors both point toward more south of east motion than from mean steering flow aloft alone. This being said, the rather far north vort and mid-level speed max path would seem to continue favor north and east of the CWA for the highest threat for a corridor of significant damaging winds. Given the conflicting signals in this regard and not much help from the available guidance, largely maintained forecast continuity. This includes a nod toward the western flank of the MCS orienting moreso from WNW to ESE and extending farther west than much of the available guidance would entail, along with a faster forward motion than much of the guidance would suggest. Very steep mid- level lapse rates and associated extreme MUCAPE reservoir, plus dynamical support and strong deep layer shear do support MCS maintenance and longevity deep into the night. At this point, think odds favor apex of a possible/likely bow echo to pass to the north (possibly just north of far NE IL). Segment extending back west into our CWA as per official forecast would then have a relatively lower end but still evident damaging wind gust threat (60-70 mph type gusts) and lesser chance for significant (75+ mph) gusts. Of concern for the flash flooding risk, should the west to east orientation materialize as the complex presses southeast across the area, forecast backward propagating Corfidi vectors slow greatly after 06z. Thus backbuilding convection along the forward flank of the MCS would have a flash flood risk. Observational trends will need to be monitored closely tonight for this. Finally, regarding the embedded QLCS tornado threat, forecast 0-3 km bulk shear magnitudes are favorable at 30+ kt. However, shear vector orientation may tend to be more parallel to the line than ideal so that tornado threat would be brief/shorter lived from any transient stronger mesovortices that can develop. There may be some lingering convection beyond 12z Thursday as the MCS exits to the east-southeast, and as mentioned earlier, we`ll need to monitor closely for signs of meteotsunami or seiche development. The true cold front will not have passed yet Thursday morning, and with the MCS expected to be primarily out of the area, any renewed showers or storms toward mid day and into the afternoon will be on lingering confluence ahead of this front and on the primary MCS outflow which may be extending northwestward through the CWA. This will eventually all be shunting southward as one boundary into the early afternoon, and isolated to perhaps widely scattered thunderstorms remain a threat along this, mainly south of I-80, ending prior to sunset (possibly well before if front clears fast enough). The high moisture and residual CAPE would support an isolated severe threat, though confidence is low. Heat and humidity on Thursday will maximize south of I-80 and especially south of a PNT to RZL line, where heat indices could approach or reach 105 degrees prior to cold frontal passage. Opted to let the midnight shift take a look at whether a Heat Advisory may be needed for the southern tier counties of the CWA. Cooler and drier air will be flowing into the area driven by brisk north-northeasterly winds through Thursday night. This will present a rebuilding of high wave action and strong currents after morning choppiness and seiche/meteotsunami potential. The dangerous swimming conditions will then linger into Friday. Given the threat for rapidly fluctuating water levels and hazardous conditions Thursday morning and more prolonged hazardous conditions developing Thursday PM, opted to issue a Beach Hazards Statement from 1 AM tonight through 7 PM Friday. Castro && .LONG TERM... 328 PM CDT Friday through Wednesday... The extended period will start off on the cooler side with highs in 70s. Continued northeast winds, while easing, will allow for high wave action and rip current risk to persist along Lake Michigan beaches and dangerous swimming conditions through the afternoon. The Great Lakes region remains under northwest flow heading into the weekend with the strong upper jet beginning to depart to the east. As it does so the local area will reside near the right entrance of the jet on Saturday with a weak mid-level disturbance also moving across the area. This will provide support for showers and a few thunderstorms on Saturday as a cold front moves across the area. Beyond Saturday, the extended period looks fairly quiet with surface high pressure centered over the area and generally cooler conditions in the 70s as the upper trough axis amplifies over the area through midweek. Petr && .AVIATION... For the 00Z TAFs... Concerns through the forecast period include: - Potential line of severe convection with strong winds during the early morning hours and proceeding wake low winds - NE wind shift with a cold front early Thursday afternoon - MVFR ceilings behind the cold front Thursday afternoon VFR conditions are expected through this evening, but focus is on the potential impacts of imminent convection over central Minnesota. Convection is expected quickly develop and grow upscale into a severe MCS as it tracks southeastward through Wisconsin this evening. Northeast Illinois will likely be located on the southwest extent of this MCS, which is progged to reach the Chicago metro as early as 06Z, but possibly anytime between 06-09Z. While the core of the MCS may miss the terminals to the northeast, convective wind gusts of 35kt+ are possible along with very heavy rain reducing visibility to IFR levels. Confidence remains medium on convective coverage into northeast Illinois, but some form of an outflow wind shift to the N is expected. If the stronger convection materializes farther southwest through the Chicago metro, SW wake flow winds gusting to 30 knots are a possibility for a couple hours behind the convection (pre-dawn hours). Winds should settle W or SW for several hours while gusting around 20 knots Thursday morning before turning NW late in the morning and finally turning NE around noon as a cold front shifts through the area. Behind the front, a period of MVFR ceilings are possible through much of the afternoon before scattering by the evening. Kluber && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ103-ILZ104 until 7 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 until 7 PM Friday. LM...Small Craft Advisory...nearshore waters until 1 PM Friday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
848 PM EDT Wed Jul 28 2021 .SYNOPSIS... A cold front will approach the area tomorrow into tomorrow night. High pressure will build in for Friday into this weekend, bringing drier and cooler conditions. Another system may impact the area early next week. && .NEAR TERM /THROUGH THURSDAY/... 8:45 PM UPDATE: Current radar imagery depicts widely scattered showers and thunderstorms across northern VA and into northern and western MD. Also notable in radar imagery has been the Bay Breeze, which has made it well into northern VA at this time. Storms have struggled to get going in these regions however, owing to weak mid-level lapse rates and abundant dry air aloft. However, the surface level dry air has allowed for some decent wind gusts even out of relatively weak showers (up to 30 mph or so). What this has also done is allowed for plenty of residual outflow boundaries to be lying around. Could see those interact with the Bay Breeze and locally enhance convection. For now, seems like that is becoming less likely as we get further past sunset. The 00z IAD RAOB continued to show 1000 J/kg or so of MLCAPE, so there is still at least some instability around. RAP mesoanalysis even shows an increase in MLCAPE through the next several hours, albeit slight. So, can`t completely rule out a rogue stronger storm, but for now at least, seems as though the dry air and weak lapse rates are winning out. Per the latest RAP mesoanalysis however, the region does lie within the left-exit region of an approaching upper jet. So, activity may last into the overnight hours as ascent attendant to the upper level jet streak spreads over our area. Recent runs of the HRRR have this type of scenario playing out, with storms lasting until after midnight. Storms should eventually dissipate much later tonight, giving way to partly to mostly cloudy skies late tonight. Lows overnight will be in the upper 60s to lower 70s. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... Tomorrow`s forecast is a challenging one locally. A very strong MCS is expected to develop over the Upper Midwest/Lower Great Lakes this evening into tonight. This MCS should eventually weaken overnight as it moves into a lower CAPE environment over the Ohio Valley. A remnant outflow boundary/convective debris will spread over at least northern portions of the area tomorrow morning, with a connectively enhanced speed max in the 700-500 hPa layer following immediately in its wake. There is a wide spread of possible solutions in model guidance with respect to subsequent development of storms across our area tomorrow. Some solutions try to refine storms along the leading edge of the remnant outflow as it sweeps eastward across the area. Other solutions keep this activity suppressed. Other solutions fire additional storms in the wake of the convective debris. Some solutions do not. The environment in the wake of the leftover convective debris as the convectively enhanced speed max moves overhead is concerning. Models such as the NAM and Euro spread a belt of 40-50 knot flow in the 700-500 hPa layer over the northern half of our CWA by around peak heating. If we were to destabilize and storms were to form in that type of environment, the potential is there for a significant severe weather event, with very high winds, large hail, and tornadoes all possible. However, there`s considerable disagreement amongst the various models as to if and where storms will form in the wake of what`s left of today`s Upper Midwest system. Strong MCSs are often not handled well by both the CAMs and global guidance, and any system that forms today will have a strong influence on our weather for tomorrow. As a result, confidence in the evolution of storms tomorrow remains low. Confidence should gradually increase over time as today`s system gets going and becomes better handled by model guidance. We`ll continue to refine our forecast for what is a low confidence, but also potentially high impact severe weather event tomorrow. A cold front will press through the area tomorrow night and high pressure will build into the area on Friday. Much drier air will work into the area on northerly flow behind the cold front. Temperatures will remain warm with highs in the high 80s, but dewpoints will drop into the 50s, making it feel a bit more comfortable. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Cooler temperatures than recent days and dry conditions with high pressure moving overhead Saturday. High temperatures reaching the middle 80s. The high shifts eastward to allow for a return flow to bring in more moisture and warmth from the south Saturday night into Sunday. A couple of showers could develop in parts of the region Saturday night with a chance of additional showers and a thunderstorm or two Sunday with a cold front approaching and moving through the region. Sunday`s highs will reach the middle to upper 80s. A few lingering showers are possible Sunday night into Monday with a bout of dry conditions to follow later Monday afternoon and Monday night. Highs Monday in the middle 80s. Tuesday appears to have some modest uncertainties as we could either be looking at dry conditions and temperatures in the middle to upper 80s or periods of rain with embedded thunderstorms and temperatures in the lower 80s. The first would be if high pressure hovers over us as a weak front stays well to our northwest and a possible coastal low pressure stays well to our southeast. The latter would be if the coastal low wins out and moves northeast up the mid-Atlantic seaboard. For now, we will keep an isolated shower or two for Tuesday mainly across the southeastern half of our region. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... A few widely scattered showers and storms in the area tonight, and will likely continue into the overnight hours. Have added VCTS on many terminals (not CHO though). Don`t think we see much in the way of severe weather, but could see brief restrictions if any of these wander over the terminals. For now though, most of the terminals remain dry. Prevailing VFR conditions are expected through Friday. Thunderstorms will be possible at the terminals Thursday afternoon, potentially leading to brief restrictions. The evolution of storms on Thursday is much more uncertain, but have decided to at least add some VCTS to the northern terminals (so just excluding CHO) during the afternoon. If thunderstorms were to occur tomorrow, they could potentially be very strong, with very high winds and hail possible. However, it`s also possible that storms avoid the terminals. For now, wanted to add in an inclusion of VCTS just to provide extra awareness to the potential threat tomorrow. Despite an isolated shower Saturday night and a few showers and a thunderstorm possible Sunday, expect VFR conditions. Winds northwest becoming south 5 to 10 knots Saturday into Saturday night. Winds southwest becoming northwest around 10 knots with higher gusts Sunday. && .MARINE... Sub-SCA conditions are expected in light northerly flow today. Winds will turn southerly tomorrow and may approach SCA levels briefly in southerly channeling tomorrow afternoon. However, confidence in that occurring was too low to issue an SCA at the moment. SMWs will be possible in association with any thunderstorms that move over the waters both this afternoon and tomorrow afternoon. The winds in any thunderstorms tomorrow afternoon could be very strong, with over 50 knots possible in the strongest cells. Additionally, in the wake of that frontal boundary, winds are expected to exceed SCA criteria, so have added an SCA starting late tomorrow night, which will continue through at least Friday morning. No marine hazards expected Saturday through Sunday night. Winds northwest becoming south around 10 knots Saturday and Saturday night. Winds generally southwest shifting late to northwest at 10 to 15 knots Sunday and Sunday night. && .TIDES/COASTAL FLOODING... Southerly flow ahead of an approaching cold front will likely bring tides up to action stage over the next couple days. Minor flooding may be possible at the most sensitive sites like Annapolis. Northwest flow behind the front by Friday should allow anomalies to drop. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 10 PM Thursday to 6 AM EDT Friday for ANZ534-537-542-543. && $$ SYNOPSIS...KJP NEAR TERM...CJL SHORT TERM...KJP LONG TERM...KLW AVIATION...KLW/CJL/KJP MARINE...KLW/CJL/KJP TIDES/COASTAL FLOODING...RCM/CPB/ADS
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
656 PM CDT Wed Jul 28 2021 .UPDATED for 00Z Aviation Discussion... Issued at 646 PM CDT Wed Jul 28 2021 && .SHORT TERM...(This evening through Thursday night) Issued at 343 PM CDT Wed Jul 28 2021 Surface analysis this afternoon shows a surface low over the ND/MN border with is warm front snaking SE through central MN into northern IA and its cold front sagging SW through the Dakotas. High pressure sits to the NW of this system. Aloft, a trough resides over the eastern CONUS with a large ridge over the western CONUS. While WNW- ESE is placed over the Upper Midwest, several embedded shortwaves are immersed within the flow, and are expected to jet across the region through the rest of this afternoon and evening. Clouds have dispersed efficiently this afternoon across central- southern MN well after this morning`s convection. Combined with southerly winds, this has allowed temperatures in western MN to soar into the 90s with much of the area having a surge in moisture, pushing dewpoints into the 70s. While this certainly has contributed to high heat index values over 100 (and near 110 in some areas), this is also allowing instability to surge across the area. SPC mesoanalysis pages indicate MUCAPE values as high as 4000-5000 j/kg over western and southern MN, but there is still a relative minima of 1000-2000 j/kg over western WI, which is eventually where storm development is expected. The surface low is expected to drive ESE across southern MN (atop the TC metro) and into central WI by midnight, with high pressure then filling into MN/WI overnight through Thursday. CAMs, which differing in exact placement, are still indicating a good degree of confidence in t-storm development over northern MN and growing into an organized complex that will push SE through east-central MN and west-central WI then into southern WI late this afternoon through this evening. The trickiest part is how far west the storms may develop as the HRRR still confines the storm development into WI while other CAMs have nudged the convection a bit further west into MN. Still, there is little to stray from the idea of having a powerful bowing complex for western and southern WI this evening which may well contain damaging winds and large hail. Later mesoscale discussions from SPC will capture more detailed elements so keep up with the latest discussions on their end to see how this potential severe weather event will develop. Once the storms exit the area and the cold front pushes through, a noticeably calmer/cooler/drier environment will settle upon the WFO MPX coverage area for tomorrow. This will drop highs from the 90-100 degree range today to the 80-85 degree range tomorrow. More notably, dewpoints will drop from the low-mid 70s to the 50s, making for much less humid conditions. The only other issue to deal with in the short term will be the return of wildfire smoke to the area. HRRR Smoke modeling plus collab from the MPCA indicates that air quality will suffer with subsidence forcing smoke aloft down near the surface. As such, have added smoke mention to the gridded/text products along with the Air Quality Alert issued by the MPCA. .LONG TERM...(Friday through Wednesday) Issued at 343 PM CDT Wed Jul 28 2021 Much more tranquil conditions are expected across the region from the end of this week into the middle portion of next week. Weak isentropic lift in advance of a frontal system developing over the central Plains Friday into Saturday may result in isolated to scattered showers and thunderstorms over far southwestern portions of the area. Additional isolated showers and thunderstorms may be possible Saturday in western Wisconsin as a secondary cold front drops through the area. While this front will not be much in terms of generating precipitation, it will be a reinforcing shot of cooler and drier air across the region for early next week. From Sunday onward, a dry forecast is in place. In addition, temperatures will again take a bit of a hit, with highs falling back to the upper 70s to lower 80s along with lows falling into the 50s to lower 60s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 646 PM CDT Wed Jul 28 2021 Scattered showers are possible at the Minnesota TAF sites, and strong thunderstorms are possible in the Wisconsin TAF sites this evening. The precipitation should exit the region overnight, with VFR conditions and northwest winds expected for Thursday. KMSP... The higher chances for thunder should be east of KMSP, so have VFR showers in the TAFS. There is still a chance KMSP could see a storm, but did not include mention in the TAFS. Precipitation chances should end by midnight, and then expect VFR conditions with /OUTLOOK FOR KMSP/ Fri...VFR. Winds SE 5-10 kts becoming SW. Sat...VFR. Winds NW 10-20 kts. Sun...VFR. Winds N 10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Excessive Heat Warning until 9 PM CDT this evening for Anoka-Benton- Blue Earth-Brown-Carver-Chippewa-Dakota-Faribault-Hennepin- Kandiyohi-Lac Qui Parle-Le Sueur-Martin-McLeod-Meeker-Nicollet- Pope-Ramsey-Redwood-Renville-Rice-Scott-Sherburne-Sibley- Stearns-Stevens-Swift-Waseca-Washington-Watonwan-Wright-Yellow Medicine. Heat Advisory until 9 PM CDT this evening for Douglas-Freeborn- Goodhue-Isanti-Mille Lacs-Morrison-Steele-Todd. WI...None. && $$ SHORT TERM...JPC LONG TERM...JPC AVIATION...JRB
Area Forecast Discussion
National Weather Service Phoenix AZ
513 PM MST Wed Jul 28 2021 .UPDATE... Updated Aviation discussion. && .SYNOPSIS... One more day of warmer and minimal storm chances today before rain chances increase late in the week. Another weather disturbance expected to affect the region bringing a return to more widespread shower and thunderstorm activity starting Thursday afternoon, likely persisting into the weekend. Drier conditions should then prevail by early next week. && .DISCUSSION... Monsoon activity across the region has returned to a more typical pattern this afternoon with storms mainly developing over SW AZ and SE CA as a weak inverted trof moves across that region. This is the same inverted trof/jet max that brought TS activity to SE AZ and areas of strong winds/blowing dust to parts of South-Central AZ yesterday afternoon/evening. Latest WV satellite imagery is showing somewhat drier air filtering into eastern/central AZ, which is expected to greatly limit TS activity over that region this afternoon/evening. The 12Z HREF agrees with the lower potential compared to yesterday, showing isolated to scattered storms this afternoon along the Mogollon Rim and over extreme southeast Arizona through this evening. The semi quiet monsoon period will quickly come to an end on Thursday as a well defined, but weakening upper level low center currently moving westward through southern Texas/northern Mexico moves into the region. During the day Thursday, broad upper level ascent will spread westward across much of Arizona as the trough enters the region. Moisture levels and instability will be sufficient for scattered to possibly widespread storms developing across the eastern Arizona high terrain Thursday afternoon with strong winds, heavy rainfall, and localized flooding all possible. Latest (12Z) SPC HREF guidance is showing 50-70% chance of wind gusts aoa 35 kts across south-central AZ/SW AZ during the afternoon/evening hours on Thursday as it show an rather organized area of convection marching westward into the lower deserts, with even a 10+% chance of wind gusts aoa 50 kts. ALthough fairly rapid storm motion will limit rainfall totals somewhat, the strong/severe nature of these storms will still likely allow them to produce localized flooding, especially over the burn scar areas. Latest HRRR and HREF guidance is showing this complex of showers/TS progressing westward to about the Colorado River Valley during the late evening hours on Thursday/into early morning, but instability will be much more limited farther west. As is typical during these overnight hours. the main impact of these storms further west will be localized flash flooding, with wind and dust being a lesser threat. Given the heavy rainfall threat across the region, WPC has upgraded their ERO to "slight" for eastern AZ (including southern Gila County) on its day 2 outlook and much of western AZ (including LA Paz and parts of Yuma County on its day 3 outlook. The inverted trough is forecast to exit the region to the northwest Friday morning, but not before spreading modest moisture throughout our area. Storm chances for Friday still look to be a bit more uncertain with the quicker progression of the inverted trough and the possibility of storm suppression due to large areas being worked over by Thursday`s activity. Sufficient moisture will still be in place in most areas Friday, but some drying is now forecast across eastern Arizona. Shower and storm chances for Friday afternoon and evening are now more favored from Phoenix westward with the help of broad ascent associated with a south to north oriented upper level jet over California. Should also have some isolated to scattered storms across the eastern Arizona high terrain, but the drying coming out of New Mexico should limit coverage. Storm chances Saturday look to shift back to the east with another jet streak coming up from the south providing ascent more focused across central and eastern Arizona while better moisture is again seen across eastern Arizona. Near to slightly above normal monsoon moisture levels and forecast soundings for Friday and Saturday point toward a mix of storm threats from strong winds to locally heavy rainfall and possible flooding. Drier air will begin working in from the southwest starting Sunday, likely ending storm chances across most of the western deserts and considerably lowering chances elsewhere. The southwesterly drying flow will result from the subtropical high weakening while shifting south and an upper level trough becoming the dominant feature along the West Coast. This unfavorable monsoon flow pattern should persist through early next week with another high center forming to our southwest on Monday and even drier northwesterly flow spreading through the region. Minimal storm chances over the eastern Arizona high terrain are expected for Monday and Tuesday, but for now it seems the lower deserts will be dry for a few days. Eventually, model ensembles show the new high center shifting northeastward into the Four Corners area later next week which will likely bring a return to more favorable monsoon moisture flow out of the southeast and increasing storm chances. Temperatures today and Thursday should be the warmest of the week with highs across the western deserts between 109-112 degrees to 102-105 degrees in the Phoenix area. Cooling will occur by Friday and last through the weekend with forecast highs from the upper 90s in the Phoenix area to 100-105 degrees over the western deserts. Temperatures should return to near normal readings for the western deserts during the first half of next week, while the south-central Arizona deserts will likely fall just short of normal readings. && .AVIATION...Updated at 0020Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Thunderstorm chances on the Valley floor remain below 10% through mid afternoon Thursday. Surface winds are expected to favor westerly directions this evening. However, that may last only until 04Z or so before more variable directions develop (but with speeds remaining below 10kts). Typical light nocturnal winds are anticipated to develop by 07Z or so (earlier for KSDL and KDVT and later for KPHX). Late tonight and during the morning Thursday, thick high clouds are anticipated. There are some indications of embedded sprinkles. Not enough to go on at this time to insert VCSH or have any noteworthy ceiling altitudes. Thursday afternoon and evening is anticipated to be quite a bit more active with more storms over the higher terrain north and east of the Phoenix area as well as southeast Arizona. This will lead to a significantly higher potential for impactful outflows and storms on the Valley floor (35-45% chance). Uncertainties remain in terms of storm coverage as well as timing and strength of outflows. Southeast California/Southwest Arizona including KIPL and KBLH: Thunderstorm chances at the TAF sites remain below 10% through mid afternoon Thursday before increasing to 15-25% Thursday evening. Apart from thunderstorms, winds are anticipated to remain light and favor south and southeast directions. High clouds will increase considerably late tonight and hang around for much of the day Thursday. && .FIRE WEATHER... Saturday through Wednesday: Unsettled conditions are likely through the weekend with a couple of weather disturbances moving through the region. This should bring daily shower and storm chances across the entire area on Saturday before decreasing chances from west to east Sunday through next Wednesday. Main threats will be strong thunderstorm winds, heavy rainfall and localized flooding. Temperatures will range from near to slightly below normals the bulk of the period. Minimum afternoon humidity values will range from 25-45% through the weekend before falling back to 15-30% early next week. Overnight recovery will be mostly good to excellent in a 40-80% range. Apart from thunderstorms, winds will favor typical daily upslope/drainage patterns. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Percha/Kuhlman AVIATION...AJ FIRE WEATHER...Percha/Kuhlman
Area Forecast Discussion
National Weather Service Riverton WY
455 PM MDT Wed Jul 28 2021 .SHORT TERM...(This evening through Thursday night) Issued at 309 PM MDT Wed Jul 28 2021 Complicated weather pattern today has brought a host of different weather to western and central Wyoming. First, a cool front moved south out of Montana overnight into the morning hours east of the divide. Yes, it is cooler than yesterday, but it`s still quite warm and feels warmer because overnight temperatures did not cool off as normal. Also, the northerly flow has brought increased smoke into the basins, reducing visibilities and decreasing air quality. Thus, an the Air Quality Alert has been extended through at least tomorrow. Second, monsoon moisture along with increased instability and buoyancy have brought scattered showers and thunderstorms to much of western Wyoming. Storm motions are very slow and precipitable water amounts are very high, around 150 percent. Thus, the likelihood of flooding has increased this afternoon and evening due to precipitation rates on the order of 1 inch in 30 to 45 minutes. High resolution models continue to show more organized areas of moderate precipitation develop across western WY late this afternoon into the evening hours. Isolated storms are possible early in the evening along the eastern foothills of the Wind Rivers and southern Absarokas, which then move northeastward. The HRRR continues to show some storms developing around midnight from Buffalo SW toward Shoshoni. So, expected isolated showers and very isolated thunderstorms after midnight tonight. The shortwave trough rotating around the high seems to hang along a boundary across northern WY to bring precipitation to north- central WY Thursday morning. Otherwise, Thursday morning will be mostly to partly cloudy across the area with another possibility of above normal minimum temps. Thursday will be similar to today as slow moving storms develop, mainly over the mountain areas, with a very high chance of heavy rainfall rates which could again lead to flooding. Some of the storms over Natrona county could be strong too, with SPC highlighting the area for a marginal risk of severe storms. The focus Thursday late afternoon and evening will be from the west-central mountains northeastward to the Bighorns, though everywhere across the area will have a chance of storms and precipitation. The shortwave trough riding around the high Thursday evening should bring moderate precipitation to a large area from the eastern Wind Rivers NNE across the Bighorns and Johnson County. Thursday night should be a focus for the east side of the Bighorns for heavy precipitation, according to the NAM, GFS, and HREF. Afternoon high temperatures should decrease another 5-8 degrees Thursday over Wednesday, and humidities will increase as well, especially in areas of precipitation. There is a possibility of fog in the western valleys Thursday morning as recent precipitation will add to low level moisture. Generally wind flow the next couple of days will be northwest across western WY, and north to northeast east of the divide into Sweetwater County. .LONG TERM...(Friday through Wednesday) Issued at 309 PM MDT Wed Jul 28 2021 Monsoonal moisture continues to push into the region Friday and Saturday, as a surface high sits to the southeast and meridional flow aloft over the western CONUS helps usher higher PW air northward. Despite continued cooling of temperatures (lower highs generally in the 80s), there should be enough instability for continued widespread showers and thunderstorms. Given the amplified large- scale ridge over the region, storm-motion will be quite slow. This leads to continued localized flooding concerns, especially over steep terrain where rainfall can be funneled. Saturday night into Sunday, a broad surface high slides down the Plains from Canada. The pressure gradient around this high is forecast to push drier and slightly cooler air westward. Locations east of the Divide should see less shower activity during the afternoon. Far western and southwestern Wyoming will still have a solid moisture connection in the monsoonal flow, so scattered storms continue to be possible there. The EC and GFS disagree on how to bring a well-defined shortwave through the ridge early next week. The GFS is more progressive and brings additional lift into central Wyoming Monday, which would translate into additional chances for daytime showers and thunderstorms. Despite the differences, both models keep early week temperatures about 5 degrees below average due to increased cloud cover and a relatively moist air mass. && .AVIATION...(For the 00Z TAFS through 00Z Friday) Issued at 445 PM MDT Wed Jul 28 2021 Scattered showers and thunderstorms will occur in the west and central through 06Z. Only isolated activity will occur elsewhere. Surface winds will generally be light; however, in the vicinity of thunderstorms, brief erratic wind gusts of 30 to 40 kt are possible. Showers will persist into the early morning hours Thursday. Thursday begins with abundant high cloud cover, and by the afternoon, additional showers and thunderstorms are forecast to develop. Lightning, brief heavy rain, and gusty winds will be the main threats, but small hail cannot be ruled out. && .FIRE WEATHER... Issued AT 200 PM MDT Wed Jul 28 2021 Hot and dry is quickly turning to warm and wet today and the rest of the week. Scattered showers and thunderstorms across western WY will continue into the evening with heavy rainfall a good possibility. Isolated showers and storms will then continue overnight and possibly move eastward into central and northern WY. Gusty north winds east of the divide will continue into the evening hours as well. Thursday will continue with isolated showers in the morning transitioning to scattered showers and thunderstorms in the afternoon and evening. Again, heavy rainfall will be the biggest threat and hopefully lightning will strike in wet areas. Thursday evening could be quite wet across portions of north-central WY. Friday and Saturday will see continued cooling temperatures as well as good chances of precipitation across much of Wyoming. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...McDonald LONG TERM...VandenBoogart AVIATION...VandenBoogart/AR FIRE WEATHER...McDonald