Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/06/20

Area Forecast Discussion...Updated
National Weather Service Billings MT
808 PM MDT Wed Aug 5 2020 .UPDATE... Much of the shower and thunderstorm activity over the Beartooth/Absaroka/Bighorn Mountains and adjacent foothills has dissipated. An isolated shower or thunderstorm is still possible over these areas this evening with a weak shortwave moving overhead. Current forecast has this handled well. Otherwise just made some adjustments to hourly temperature, relative humidity and cloud cover toward latest short-term model data. Rest of forecast is on track. Some smoke may be noticeable from central Rosebud County west/northwestward to Musselshell and northeastern Yellowstone Counties this evening as a fire burning in southwestern Custer County produces smoke that is then moved by ESE winds. HRRR model has this smoke plume very narrow and dissipating by midnight MDT so left it out of the forecast for now. RMS && .DISCUSSION... Tonight through Friday night... High pressure was building over the region today with some weak energy and moisture moving through the west side of the ridge. This was producing a few showers and thunderstorms over the higher terrain and adjacent foothills. With weak shear, most storms will be confined to the higher terrain, although a few could slide off onto the lower elevations over the west this evening. High pressure begins to shift east on Thursday as an upper trough moves into the Pacific Northwest. Temperatures will warm into the mid 90s for many places with afternoon humidities in the 20s with easterly low level flow in place. Shortwave energy and monsoonal moisture advecting into the area from the southwest will produce showers and thunderstorms. Convection will develop over the higher terrain Thursday afternoon and lift northeast through the area during the evening. Soundings showing inverted V signature, so strong winds will be the primary threat. Enough cape around for the possibility of hail, but limited shear and warm mid levels, should keep hail size from getting too large. Increasing lightning activity will pose a concern for fire starts but precipitable water values near an inch over the eastern half of the area will translate to locally heavy rain. A cold front will push into the area early Friday morning. This will provide cooler temperatures for Friday and a slight chance of a shower or thunderstorm in the afternoon and evening. The chance of convection again looks to be confined to the higher terrain and over southern locations, to the north of the frontal boundary that will be slowing pushing through northeast Wyoming during the day. High temperatures will fall from the mid 90s of Thursday, to the upper 80s on Friday, which is right around the seasonal norm. TWH Saturday through Wednesday... Drier air will surge into much of southeast Montana Saturday, but there will be a brief period of theta-e return in our far east, associated with another approaching shortwave, and this may yield a few late day t-storms east of Miles City and Broadus. Confidence is high among ensembles that we will see a drier air mass underneath zonal flow Sunday through Monday, with the northern Rockies ridge being suppressed by a trough over Alberta/ Saskatchewan. There remains differences among models in the amount of cooling we may see this far south, but the ensemble consensus is in line with the operational EC in keeping us warmer than the GFS on these days. Overall, expect near to slightly above normal temps with dry conditions. Ridge should start to rebuild by next Tuesday, and this looks like a warmer and still mainly dry day, with possible late day storms over the mountains. Deepening low over the Pacific Northwest will allow for southwest flow and increasing thunderstorm chances next Wednesday and Thursday, along with continued warm temperatures. Regarding fire weather, overall theme from Saturday and beyond is for afternoon humidity in the teens becoming more common, with poorer nighttime recovery. More typical late summer fire weather conditions as we move into mid August. JKL/TWH && .AVIATION... VFR will prevail through the TAF period. Isolated showers and thunderstorms are possible this evening west of KHWQ-KBIL-KSHR. Scattered showers and thunderstorms are expected over southern MT and northern WY Thursday afternoon into the evening. Storms Thursday could produce strong, gusty winds and small hail. RMS && .PRELIMINARY POINT TEMP/POPS... Thu Fri Sat Sun Mon Tue Wed ----------------------------------------------------------- BIL 062/095 064/088 058/089 059/087 058/087 057/089 060/092 12/T 21/U 10/U 00/U 10/U 01/U 12/T LVM 054/093 054/086 049/088 051/087 051/087 051/089 053/090 24/T 22/T 10/U 01/U 11/U 01/U 12/T HDN 061/097 062/089 056/091 058/087 056/087 056/091 058/094 02/T 21/U 10/U 00/U 10/U 01/U 11/U MLS 061/096 065/088 057/090 060/085 057/085 056/089 060/092 02/T 30/U 11/U 10/U 10/U 01/U 11/U 4BQ 060/095 063/089 058/090 060/086 057/087 056/089 059/092 02/T 31/U 21/U 10/U 10/U 11/U 11/U BHK 054/092 062/090 055/088 058/085 054/085 052/086 057/090 01/U 31/U 12/T 21/U 11/U 11/U 11/U SHR 057/095 059/089 055/092 056/088 054/087 054/090 056/092 13/T 22/T 21/U 10/U 11/U 11/U 12/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Fire Weather Watch in effect from Friday afternoon through Friday evening FOR ZONE 117. WY...None. && $$
Area Forecast Discussion...CORRECTED
National Weather Service Charleston SC
912 PM EDT Wed Aug 5 2020 .SYNOPSIS... A stationary front will remain over the area through the weekend. Atlantic high pressure will then linger off the coast through early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A relatively concentrated cluster of showers/tstms extending from Portal and Pulaski east to Egypt and Stilson at 07/01z is slowly working east and southeast along an increasingly ill- defined outflow boundary. This convection is being fed by lingering unstable conditions in the Ludowici-Savannah region where MLCAPEs are still averaging 2500-3000 J/kg per latest SPC instability progs. Expect this activity to keep propagating to the east/southeast over the next few hours along a small northwest- southeast oriented H8 theta-e ridge axis that is directed into the Savannah Metro Area per latest RAP analysis. Increased pops to 60-70% in this region through midnight. Later tonight, channeled shortwave energy passing through aloft could act to spark additional mostly isolated showers/tstms during the early morning with the better chances occurring along the southern South Carolina coast. Adjusted pops slightly to reflect this trend. Lows will range from the lower 70s well inland to the lower 80s and Downtown Charleston. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... A mid-level trough will encompass the Great Lakes Region and then shift to the east southeast, encompassing much of the Atlantic Northeast and Southeast through Saturday. As a stationary front remains over the area, moisture will be plentiful and is expected to linger with PWATS around 1.75 to 2.25 inches. Isolated to scattered showers/thunderstorms are expected each afternoon with plentiful instability and along the sea breeze. Overall, any thunderstorms that form are expected to diminish after sunset with the loss of daytime heating. Temperatures will remain near normal and as of now, maximum heat indices are expected to be between 98 and 106 degrees. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... There isn`t much change to the weather pattern expected early next week with the continuation of near to above normal POPs and temperatures near normal. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... VFR. An outflow boundary north of KSAV could spark an isolated tstm near the terminal through 03z, so this will need to be watched. Guidance suggests scattered showers/tstms will develop near or just west of the terminals Thursday, initially near KSAV then near KCHS. Will carry VCTS 14-19z at KSAV, but hold off on any mention KCHS since it appears better rain chances will remain just to the west. Extended Aviation Outlook: Brief flight restrictions are possible due to showers/thunderstorms, mainly each afternoon and evening. && .MARINE... Tonight: South winds less than 15 kt will prevail with seas 2-4 ft. Thursday through Monday: Overall, winds will remain generally south. Winds are expected to remain below Small Craft Advisory but could become gusty up to 15 kts along the sea breeze each afternoon and during the nocturnal surge. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
555 PM MDT Wed Aug 5 2020 .SHORT TERM...(This evening through Thursday) Issued at 330 PM MDT Wed Aug 5 2020 Forecast challenges transitioning from severe thunderstorms this critical fire weather conditions through the remainder of the week. Currently...Trough of low pressure extends along the front range of eastern Colorado northwestward into Laramie and eventually to near Riverton this afternoon. Radar has begun to blossom on radar this afternoon...similar to what the short range guidance has been showing. Probably better today than over the past several days. Less shear today and a little more stable over yesterday. RAP analysis showing SB CAPE of around 1800 J/KG down here near Cheyenne to around 1000 J/KG up near Douglas. Off to the west over Carbon County...very dry conditions being observed with Tds in the low 20s. Red Flag Warnings look to be panning out out that way and will continue the current afternoon RFWs for today. Short range guidance showing storms moving out into the Panhandle towards 00Z. Should we get this rainfall this believe we stand a good chance at patchy fog with southeasterly upslope flow. Did add patchy fog into the forecast for the Panhandle below 4500 feet elevations. SREF hinting at lower conditions out there towards 12Z as well. Drier and breezier Thursday with low humidity spreads east. Looks like surface boundary shifts east to near the Wyoming/Nebraska state line. GFS 700mb winds west of the Laramie Range critical fire weather conditions look to be certain out west. Continued the Red Flag Warnings for FWZ 303 through 308. Best chances for any afternoon showers/storms look to be east of the Laramie Range. Very dry conditions Friday as westerly winds continue. 850mb humidity in the Panhandle falls to 12 percent. Did issue a Fire Weather Watch for zones we currently have in warnings for Friday. Later shifts may need to add the Summit and points east as we get closer to Friday. .LONG TERM...(Saturday through Tuesday) Issued at 318 AM MDT Wed Aug 5 2020 A broad upper high will hold over much of the southern half of the country through the period with the westerlies and embedded shortwaves being lifted to the north along the international border. Overall this will provide mainly dry and warm weather to the CWA with just isolated convection possible where weak shortwaves clip the CWA, right now looking like later Saturday and again Tuesday. Temperatures will be above seasonal averages with little day-to-day changes. && .AVIATION...(For the 00Z TAFS through Thursday afternoon) Issued at 555 PM MDT Wed Aug 5 2020 Widely scattered thunderstorms across the eastern plains of Wyoming and western Nebraska will gradually diminish in intensity this evening through 02z, especially for KSNY and KBFF this evening. Will have to watch for fog or low CIGS tonight in areas that received decent rainfall across the panhandle of Nebraska. Will keep out of TAF for now. HAZARDS/WEATHER TRENDS: Brief MVFR VIS in any thunderstorm activity this evening until 02z or 03z, then VFR for the rest of tonight and into early Thursday morning. Low confidence for fog and low stratus late tonight for the western Nebraska terminals. && .FIRE WEATHER... Issued at 330 PM MDT Wed Aug 5 2020 Critical fire weather conditions ongoing this afternoon across Carbon County where Red Flag Warnings are in effect through 8 PM this evening. Dry/Breezy conditions return Thursday for areas west of the Laramie Range. Red Flag Warnings in effect for FWZ 303 through 308 Thursday. Conditions expected to continue into Friday with a Fire Weather Watch in effect Friday afternoon. See a slight reprieve Friday night into Saturday as a cold front moves into central Wyoming. This will be short lived though as breezy/dry conditions return Sunday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Red Flag Warning until 8 PM MDT this evening for WYZ303>307. Red Flag Warning from 11 AM to 8 PM MDT Thursday for WYZ303>308. Fire Weather Watch from Friday morning through Friday evening for WYZ303>308. NE...None. && $$ SHORT TERM...GCC LONG TERM...RE AVIATION...TJT FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
640 PM CDT Wed Aug 5 2020 ...Updated aviation discussion... .SHORT TERM...(This afternoon through Thursday night) Issued at 1200 PM CDT Wed Aug 5 2020 After yet another MCS last night, the sky had cleared completely as of midday, with only a few lingering patches of dissolving stratus. A beautiful afternoon will be enjoyed, particularly considering how hot it can be this time of year, with sunshine, lighter SE winds, and temperatures continuing well below normal. All zones will be dry through at least 7 pm. Yet another MCS is expected tonight, though this time models are in agreement the most organized complex will be focused on NW Kansas (WFO Goodland`s CWA) this evening. CAMs show this complex, or a weakening version of it, arriving across the northern zones (particularly I-70 corridor) by around midnight. 12z NAM/GFS and HRRR all grab onto another shortwave embedded in the NWly flow aloft, and generate scattered convection further south into SW Kansas tonight. Enough evidence to nudge up pop grids to 50% for most zones, and may need to be increased further. Severe weather is not expected, but can`t rule out some wind gusts to near 50 mph and/or small hail. With continued moist light SEly boundary layer flow, short term model consensus is to develop widespread stratus late tonight and Thursday morning (most likely in areas with wet soils/recent rainfall). Temperatures sunrise Thursday a few degrees warmer than recently, in the lower to mid 60s. After morning convection wraps up early Thursday in the SE zones, the daylight hours will be dry and warmer. Afternoon temperatures will warm well into the 80s, with lower 90s adjacent to Oklahoma. Light SE winds will continue. Convection chances will wane significantly Thursday evening, with most locations remaining dry. Rising heights and lack of focusing mechanisms are expected to end the MCS parade Thursday night. .LONG TERM...(Friday through Wednesday) Issued at 151 PM CDT Wed Aug 5 2020 Traditional hot and dry August weather will return during this period, courtesy of a dome of high pressure aloft expanding its influence across the plains. The heat will return quite noticeably Friday afternoon, with all locations reaching the upper 90s, with a few locales (Oklahoma border/Red Hills) eclipsing 100. Moist soils and green vegetation from recent rainfall will work against the heatwave, at least for a few days, keeping triple digit readings relatively limited. Expect no changes over the weekend, with upper 90s common each afternoon. Morning sunrise temperatures will also be much warmer, commonly in the lower 70s. Winds will be S/SW and relatively light through the weekend. All grids are dry for all zones Friday through Sunday. Starting around Monday, 12z ECMWF suggests a more interesting NWly flow pattern will evolve. As the upper high retrogrades to near El Paso Monday evening, the synoptic pattern will likely favor MCS generation across/near Kansas again early next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 640 PM CDT Wed Aug 5 2020 Thunderstorms in eastern Colorado this evening are expected to move out into western Kansas again overnight, weakening in the process. Latest short term model trends continue to show the Hays and Garden City terminals to be the most favorable locations for any impacts. Stratus development still looks like a possibility later tonight into Thursday morning and have maintained at least MVFR cigs at most locations to reflect this. && .PRELIMINARY POINT TEMPS/POPS... DDC 65 88 68 98 / 50 10 10 0 GCK 63 90 66 95 / 50 0 10 0 EHA 64 92 67 98 / 30 10 20 0 LBL 65 94 67 100 / 50 10 10 0 HYS 64 85 68 94 / 50 10 10 0 P28 67 90 70 97 / 40 30 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Turner LONG TERM...Turner AVIATION...Gerard
Area Forecast Discussion
National Weather Service Huntsville AL
749 PM CDT Wed Aug 5 2020 .NEAR TERM...(Tonight) Issued at 749 PM CDT Wed Aug 5 2020 A small cluster of showers and thunderstorms was entering Marshall and far northeast Cullman County. This was along a weak area of convergence along the frontal boundary that was sitting near or just northwest of the I-59 corridor. Dew points were around 70F along this boundary, and the 00Z BMX sounding indicated an SBCAPE of around 2k J/kg. Successive HRRR runs have maintained some convective activity along and east of I-65 this evening, if not later. For now, will extend PoPs thru 06Z in this corridor along the boundary. .SHORT TERM...(Thursday through Friday) Issued at 251 PM CDT Wed Aug 5 2020 That low-level boundary will remain stationary Thursday, and should continue to focus scattered showers/storms over NE AL again tomorrow afternoon. The mid-level drying seen today may moderate somewhat tomorrow, but PWats should still remain below normal, and that may still reduce precip coverage slightly. The impact of all this means that tomorrow should be very similar to today, with highs topping out near 90. Some very minor moisture recovery is possible Friday, but the baggy mid- level trough axis in place over the area will finally slide east, placing the area in a relatively drier NW flow. Much of the model/ ensemble guidance keeps the region completely dry for Friday, although a few rogue showers could crop up near the Georgia border. With fewer clouds/showers, temperatures should reach the lower 90s more readily, and it is possible that blended guidance is too low. .LONG TERM...(Friday night through Tuesday) Issued at 251 PM CDT Wed Aug 5 2020 The weak upper level trough positioned to our northeast will lift up and out of the east coast as we approach the weekend. A trough building into the Pacific NW will help push a ridge into the TN Valley, and its influence will lead to decreasing rain chances and increasing temperatures as we round out the week. Diurnal convection is expected to return this weekend, and thanks to a surge of moisture associated with a lingering warm front, heat indices will once again trend towards 100 degrees. As the Pacific NW trough pushes eastward early next week, weaknesses begin to develop in the governing ridge. This coupled with the push of the stalled front northward into the TN valley and shortwave disturbances traversing the ridge will lead to increased chances for the development of scattered showers and thunderstorms. Despite the likelihood of convective development, temperatures will remain seasonable in the lower 90s during the day and low 70s at night. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 514 PM CDT Wed Aug 5 2020 VFR flight weather conditions are forecast during the period. The exception could be patchy BR/FG early Thursday morning, but have left out of the TAFs. Also, isolated SHRA or TSRA are possible Thursday afternoon, mainly east of the KHSV area. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...17 SHORT TERM...BCC LONG TERM...LH AVIATION...17 For more information please visit our website at
National Weather Service Wilmington OH
900 PM EDT Wed Aug 5 2020 .SYNOPSIS... Surface high pressure over the western Ohio Valley will provide mostly dry conditions and unseasonably mild temperatures through the end of the workweek. Warmer and more humid air will this weekend, with increased chances for precipitation by early next week. && .NEAR TERM /THROUGH THURSDAY/... Surface high pressure is currently centered over the southern Great Lakes, extending into the northern Ohio Valley. A relatively dry air mass is in place -- with dewpoints generally in the 50s. Dewpoints are in the 60s in parts of the far southern / southeastern CWA. Overall, the forecast appears to be largely on track, with one minor change for the southeastern ILN CWA. The HRRR has been very consistent in producing a band of developmental showers in the 06Z-12Z time frame, with some support from the RAP as well. This largely appears to be a result of mid-level forcing, with some weak ascent and moisture advection ahead of a 500mb wave. It is entirely possible that some precipitation may develop, but fail to reach the ground due to the dry air in the low levels of the atmosphere. Nonetheless, there is enough evidence in the models for a 20-PoP (which still suggests a lack of measurable precipitation as the most likely scenario). The dry air near the surface will also limit the potential for river valley fog, so this has been kept out of the grids. Min temps were reduced by about a degree CWA-wide based on current trends. Previous discussion > High pressure centered over the lower great lakes/western Ohio Valley and overall northwest flow will keep cool and dry conditions through tonight. Diurnal clouds will slowly dissipate this evening, and the thick cirrus currently lifting through the region will also lift north of the area. While an upper level disturbance will pivot into the region late tonight, very dry low levels will keep dry conditions overnight. Overnight lows will moderate slightly from last night, ranging from the lower/mid 50s north to lower 60s in the southeast where increasing clouds expected. Light and shallow valley fog is possible in areas outside of the increasing clouds in the southeast. && .SHORT TERM /THURSDAY NIGHT/... Weak instability coincident with a mid level trough will advect in a little more substantial low level moisture in the southeast forecast area late tonight and during the day Thursday. This will be on the southeast edge of the surface high and will bring a very slight potential for afternoon convection near Portsmouth/Vanceburg Thursday afternoon. Confidence fairly low, but with some potential in the CAMs, it can`t be ruled out so continued the mention of a stray shower. Across the north, a shallow mid level trough and associated will continue to pivot through the area, but dry low levels will keep any precip chances at bay. Highs slightly warmer on Thursday into the upper 70s and lower 80s area- wide. For Thursday night, the moisture associated with the weak shortwave in the SE will pivot northeast of the area, and while surface flow remains northerly, upper level flow becoming a bit more westerly/southwesterly. Moisture and temperatures will begin slowly trending to more seasonable conditions. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Period begins with a H5 shortwave trof over the Great Lakes. Under this upper trof is located high pressure at the surface. The trof will slide into the Appalachians by Friday evening. The low levels look pretty dry, so despite some upper support it is looking like Friday will be dry. Highs will be close to normal ranging from the lower 80s in West Central Ohio and the Whitewater Valley to the upper 80s in the lower Scioto Valley. With the H5 trof moving off the east coast Friday night, an upper ridge in the middle of the country builds a little into the Ohio Valley. Some northwest flow is still apparent over the Great Lakes. The surface high will still bring dry conditions on Saturday and highs 85 to 90 degrees. By Sunday, a stronger H5 s/w will be working east across the northern U.S./Canadian plains. In addition, southerly surface flow will start the moisture return into the region. Can`t rule out some convection popping up, so carried slight chance PoPs for all but the far east. Highs will increase a little more, ranging from the mid 80s in the West Central Ohio to the lower 90s in the lower Scioto Valley/northeast Kentucky. A cold front associated with the H5 s/w is forecast to push into the western Great Lakes on Monday. This will add surface forcing and should help with scattered thunderstorm development. Highs will remain above normal. For Tuesday and Wednesday the region will be on the southern edge of zonal flow over the Great Lakes. This will allow some upper level forcing to affect the region both Tuesday and Wednesday, which will prompt diurnal convective development. Above normal highs in the mid 80s to lower 90s are forecast. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... VFR conditions are expected through the TAF period. Cumulus clouds will dissipate in the next few hours, leaving just some cirrus overnight, along with light NNE winds. Although some MVFR visibilities are possible at KLUK, the air mass is very dry, and significant issues with fog are not expected. Tomorrow, diurnal cumulus (SCT/BKN) should develop again, along with NE winds that will likely remain below 10 knots. OUTLOOK...Thunderstorms are possible on Monday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JDR NEAR TERM...JDR/Hatzos SHORT TERM...JDR LONG TERM...Sites AVIATION...Hatzos
National Weather Service Jackson KY
1109 PM EDT Wed Aug 5 2020 .UPDATE... Issued at 1108 PM EDT WED AUG 5 2020 Showers lingered over southeast KY late this evening, and a slight POP has been extended there later into the night. After this is finished, the HRRR and new 00Z NAM contain additional development overnight or toward dawn over middle of the forecast area. Do not have confidence to jump on this just yet, but if hints of it are seen, a quick update may be required during the night. UPDATE Issued at 815 PM EDT WED AUG 5 2020 Isolated showers over the southern portion of the area were on the decline early this evening. The forecast was largely on track, and only minor changes were made in blending early evening obs into the forecast. && .SHORT TERM...(This evening through Thursday night) Issued at 410 PM EDT WED AUG 5 2020 19z sfc analysis shows high pressure moving deeper into the Ohio Valley. This has provided a partly sunny day for the area - once the fog burned off this morning. It also kept the convection at bay until just recently as a few cells have popped in our far southeast. Additionally, temperatures were a relatively pleasant upper 70s to low 80s out there at peak heating while dewpoints held generally in the low to mid 60s amid light north winds. The models are in excellent agreement aloft through the short term portion of the forecast. They all depict the main upper trough to our north gradually lifting out of the Great Lakes tonight. In its wake, another height minima rolls into the Ohio Valley on Thursday along with some accompanying energy grazing northern parts of eastern Kentucky late in the day. Given the limited model spread with these features have favored the blended NBM solution with a healthy lean on the CAMs for PoP and QPF details. Sensible weather will feature a near repeat of the weather from today into Friday morning. Look for another comfortable night with a bit more of ridge to valley temp split expected along with additional areas of fog - possibly dense in the river valleys - but not quite as extensive as it was this morning. Another pleasant day unfolds on Thursday with highs a notch higher. Look for just the small chance for some late day showers and storms - again mainly in our southeast counties where higher terrain and differential heating should yield better boundaries for initialization. Do expect the coverage to be a tad more expansive than this afternoon/early evening owing to improving upper level support by 00z Friday. Most of the activity will fade out with dark allowing another quiet and comfortable night along with more mainly valley fog into Friday morning. Only made some minor point based adjustments to temperatures on Thursday, though did put in some larger adjustments each night per the ridge to valley differences anticipated. As for PoPs, generally toned them down and smoothed them early this evening and on Thursday pm in conjunction with the consensus CAMs guidance. .LONG TERM...(Friday through Wednesday) Issued at 332 PM EDT WED AUG 5 2020 The period will begin with a upper level trough starting to pull east and northeast. At the surface an area of high pressure will be working across the Great Lakes and northern Ohio Valley. Even with the nearby trough expect only some higher terrain convection on Friday afternoon. Then Saturday dry weather is expected as high progresses further south into the Ohio Valley and heights rise from expansion of the southern ridge eastward. Then by Sunday the high pushes east and return flow sets in. This will bring ample moisture back into the region and at times in combination with ridge riding disturbances will lead to daily chances of mainly afternoon and evening showers and thunderstorms for the new work week. After having temperatures near normal for Friday, the expansion of the southern ridge and return flow will combine to warm temperatures back into the upper 80s to lower 90s for afternoon highs going into the weekend and early next week. There is fairly good agreement in the upper level pattern for the long term period. Therefore stuck close to the NBM, with minor adjustments to valleys for overnight lows and some adjustments to the afternoon highs when compared to ridges and valleys. Also adjusted PoPs down in some periods, where more uncertainty exists for when these disturbances within the periphery of the ridge arrive. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 822 PM EDT WED AUG 5 2020 VFR conditions prevailed at the start of the period, and will generally last well into the night. Very isolated light showers over the Cumberland drainage basin will die out this evening. Valley fog is expected to develop overnight and grow in breadth and depth. It is forecast to bring sub-VFR conditions to many TAF sites toward dawn, but it will dissipate quickly after sunrise. A few showers or thunderstorms may develop on Thursday afternoon, especially in southeast KY. However, the prospect is too slim to warrant inclusion in TAFs. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...GREIF LONG TERM...DJ AVIATION...HAL
Area Forecast Discussion
National Weather Service Pittsburgh PA
928 PM EDT Wed Aug 5 2020 .SYNOPSIS... Building high pressure will maintain quiet and mainly dry conditions through Thursday afternoon. Shower thunderstorm chances increase across the ridges through the week`s end, with temperature increasing through the weekend. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Made a few edits to sky cover and temperatures based on satellite and observations. Previous...Dry weather and mainly clear skies are expected tonight under building sfc high pressure. Low dew points and radiational cooling should result in low temperatures around 5 degrees below average. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/... Sfc high pressure should generally maintain dry conditions through the period for the majority of the forecast area. The exception would be across the eastern ridges, where daily shower and storm chances exist. Guidance indicates a quasi-stationary boundary draped across the Mid-Atlantic region (as noted in recent RAP 850mb temperature analysis), progged to have little movement through late Friday. Shortwave disturbances trekking through troughing aloft may serve as sufficient forcing for ascent to initiate convection near the aforementioned boundary given adequate llvl moisture. However, poor mid-level lapse rates and unfavorable effective shear should impede updraft velocity and longevity. Thus, organized, severe tstms are not anticipated. Upper troughing is progged to maintain near average temperature values through Friday; though, a pattern change should be underway. Persistent upper troughing should begin to fill in response to the amplification of broad southern CONUS high pressure, with height rises supporting a warm up and the return of above average temperature Saturday. Dry conditions will accompany warming trends under dominant high pressure. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Dry conditions and continued warmth are expected again on Sunday with little pattern change anticipated. Long range solutions suggest high pressure should begin to breakdown in response to an encroaching Midwest trough, with precipitation chances generally increasing early next week. As the trough digs across the Midwest, amplification of overhead ridging should maintain above average temperature trends into Tuesday. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... VFR and light winds expected through the TAF period other than a slight chance of of MVFR vis restrictions in the morning at FKL/DUJ/BVI/HLG. .Outlook... VFR conditions are expected for much of the week under the influence of sfc high pressure, though diurnally-driven convection may be possible each day mainly along the eastern ridges. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$
Area Forecast Discussion
National Weather Service Phoenix AZ
514 PM MST Wed Aug 5 2020 .UPDATE...Updated Aviation Discussion... && .SYNOPSIS... High pressure will shift east of the area through early next week pushing thunderstorm chances into southeast Arizona and New Mexico. This small pattern realignment will also allow temperatures to cool a few degrees, albeit still remaining slightly above normal. This unusually dry pattern during the middle of the monsoon may even persist into the end of next week. && .DISCUSSION... Current WV Satellite imagery is now showing drier air advecting into the region behind a shortwave trof that is now moving northward into extreme southern Utah, ahead of an upper trof that will be impacting our weather for at least the next few days. The drying is already being felt at the sfc this hour, with the dewpoint at Phx Sky Harbor Airport now down to 35 degrees...which helps to take a bit of an edge off the the 110+ temps that are currently being reported. latest HRRR forecast soundings are showing PWAT`s falling below 0.75 inch by early evening across South-Central AZ, with any TS activity being confined to extreme SE AZ (well south and east of Tucson). The resulting flow pattern has created a deep west to southwest flow through the bulk of the boundary layer, and 00Z regional sounding data sampled meager 6-7 g/kg mixing ratios largely unsupportive for lower elevation convection. As has been the case much of the monsoon, better quality 10-12 g/kg mixing ratios and deeper PWATs are hovering not far away in northern Mexico though the overall pattern through at least early next week will not promote effective northward transport into the forecast area. Through the remainder of this week, the aforementioned trough will edge eastward with shortwave energy mostly deflecting north into the Great Basin. H5 heights will relax into a 588-591dm range though thermal ridging ahead of the trough axis will maintain a warm midtropospheric layer. This evolution will be partially offset by a bit of cooling in the lower boundary layer; and multi-model and ensemble output reflects a very narrow range of forecast high temperatures 1F-5F above normal through the weekend. Current forecasts for the warmer Phoenix metro area suggests readings flirting with excessive heat criteria Sat-Mon. Deeper convection will be relegated almost exclusively to the SE corner of Arizona, though outflows could periodically allow some moisture to advect north and it wouldn`t be out of the question for a storm to clip southern Gila County on any given day (though chances and coverage don`t seem to warrant POPs anywhere even near 10%). NAEFS membership strongly supports weak troughing persisting along the west coast into the middle of next week, possibly being reloaded by shortwave energy diving southeast from the Gulf of Alaska. The most notable feature appears to be anomalous subtropical jet energy and a positive u-wind component punching into the SW Conus. This scenario does not bode well for any quality moisture return; and other than the potential for a brief shallow surge of moisture, forecast soundings depict little more than 5-7 g/kg mixing ratios throughout the forecast area. Similar to the short term where a stray shower/storm is possible over higher terrain locations, there is little justification for any higher POPs or expectation of rainfall in this type of pattern. && .AVIATION...Updated at 0010Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Expect southwest to west winds with gusts to around 20 kts through early evening with speeds diminishing later in the evening. An easterly wind switch is expected late tonight, but will only last through mid to late morning before again turning back to the west Thursday afternoon. Skies will remain clear through the period with only a few high based afternoon CU over the eastern Arizona high terrain. Southeast California/Southwest Arizona including KIPL and KBLH: Breezy conditions will continue through early evening with gusts up to around 25 kts. Winds will eventually diminish late tonight, but gustiness is again expected for Thursday afternoon. Skies will remain clear through the TAF period. && .FIRE WEATHER... Saturday through Wednesday: Dry conditions with above normal temperatures will prevail through the middle part of next week in a weather pattern more similar to June than August. Wetting rains should not be anticipated as thunderstorm activity shifts southeast of the districts, and only an outside chance of a shower drifting into Gila County exists. Afternoon minimum humidity values will generally fall into the teens across the eastern districts and single digits over the western deserts. Overnight recovery should range from only around 20-30 percent with locally higher values at both higher elevations and lower Colorado River valley. Some localized afternoon gusts 20-30 mph will be possible, but otherwise winds will be fairly light through the period. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Percha/MO AVIATION...Kuhlman FIRE WEATHER...MO