Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/30/24


Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
557 PM MDT Thu Aug 29 2024 ...New AVIATION... .SYNOPSIS... Issued at 347 PM MDT Thu Aug 29 2024 Scattered storms will cover much of eastern and central NM through the evening. A backdoor cold front will move into eastern NM through the night and may develop some east winds in the ABQ metro. Friday will see additional storm coverage across the northern and western parts of the state with burn scar flash flooding possible in the Sangre de Cristo Mountains. Storms will focus on the southern parts of the state through the weekend, and chances overall decrease into next week. Temperatures may begin to increase into the latter half of next week. && .SHORT TERM... (This evening through Friday night) Issued at 347 PM MDT Thu Aug 29 2024 The latest water vapor imagery shows an upper level trough passing north of NM with much drier air advecting into western NM. A remnant convective vortex from last night across Sandoval County is drifting southeast toward ABQ within a broad trough axis draped from SW to NE across NM. Storms have already fired up over the Sangre de Cristo Mts and parts of eastern NM with better sunshine and destabilization early this afternoon. The latest suite of short-term models and hi- res ensembles are in very good agreement with increasing coverage of storms along and ahead of the broad trough axis as it shifts across eastern NM this evening. The area beneath the remnant vortex may be a favored location for a few stronger cells later today between the Sandia Mts, Las Vegas, and Vaughn. Given the gradient of drier air approaching from the west a few of these cells may contain hail with gusty outflow winds and frequent lightning strikes along with heavy rainfall. Meanwhile, a backdoor cold front along the Front Range today will move southwest into eastern NM in the wake of convection over eastern NM tonight. This may generate a period of moderate canyon winds in ABQ overnight, especially if aided by storms to the east. Some low stratus is also possible along the central mt chain with increasing easterly upslope flow around sunrise Friday. Another active day is expected Friday but with a delayed onset to storm initiation. There may actually be areas of rain and embedded thunder still lingering over southeast NM and the Ruidoso area thru late morning. Guidance is in decent agreement with storms firing up over the northern and western high terrain near the remnant backdoor frontal boundary. This will also be an area with greater sunshine and heating Friday morning compared to eastern NM. Storms will then move southward toward the I-40 corridor and ABQ metro area Friday afternoon. The Ruidoso area may catch a break with a potentially more stable airmass still in place thru the afternoon. Flash Flood Watches may be needed for the HPCC and perhaps Cerro Pelado burn scar areas. Confidence is too low for the Sacramento Complex at this time. Forecast models show storms tapering off more quickly Friday evening than recent days. && .LONG TERM... (Saturday through Wednesday) Issued at 347 PM MDT Thu Aug 29 2024 A broad upper level high pressure system will set itself over CO/UT/WY for much of Saturday into Sunday. East surface winds will encompass the majority of NM, save for northwest NM on Saturday where northwest winds will be in place. Easterly upslope flow will aid in development of storms along the central mountain chain. However, an area of mid to upper level dry air will be advected into the region via the high pressure which may cap storm development, mainly in the northern half of the CWA. The forecast further complicates as a shortwave trough deepens over AZ Saturday afternoon. Ascent will increase over NM downstream of the 50-60kt jet streak associated with the AZ shortwave. Storm development will depend on the amount of lift and strength of surface upslope flow overcoming the drier mid-level air. Models disagree on location and coverage of storms on Saturday, due to difference in placement of the mid-level dry air. The GFS has storms firing over the central mountain chain and western high terrain, while the ECMWF has storms along the south central and southwest mountains. Any storms that do develop in this setup will flare up with slow west-southwest storm motions. Sunday will see a decrease in storm coverage for the central mountains as the high moves almost directly over CO, pushing drier air further south and west. The AZ shortwave trough will continue to push south and east which takes the large scale ascent and focuses it to the south of our CWA. Any storms that do form would favor the southern high terrain. Into next week, precipitation chances look to decrease across the forecast area as the CO high begins to stretch itself southwest into AZ and CA. The shortwave trough near southern NM will also flatten out, creating near zonal 250mb flow. Models begin to disagree on the strength and true location of the high moving into Tuesday and Wednesday. The GFS develops a minor secondary shortwave that pushes Gulf moisture northwards, where the ECMWF has substantial zonal flow resulting in an east-west low-level moisture gradient across the southern border of the CWA. Regardless of positioning and moisture, temperatures will likely begin to climb to near early-September average as dry air from the high continue to seeps into the region. && .AVIATION... (00Z TAFS) Issued at 545 PM MDT Thu Aug 29 2024 Complex forecast with main challenges of convective timing and progression of outflow boundaries, along with effects of a cold front currently moving into far northeastern NM, per WPC analysis. Thunderstorms ongoing in the vicinity of KTCC should move away from the terminal by around 02Z, per radar trends and latest HRRR model run. Moderate confidence that gusty easterly winds will materialize at KABQ early this evening as showers collapse over the Sandia Mountains and/or outflow from storms to the north pushes through Tijeras Canyon. As upslope flow develops behind the frontal boundary later tonight and into tomorrow, MVFR cloud decks are likely to form at KLVS, KTCC, and KROW, but confidence in MVFR ceilings is relatively low (30%). Light rain/showers may also persist through much of the night over the eastern plains of NM. && .FIRE WEATHER... Issued at 347 PM MDT Thu Aug 29 2024 There are no critical fire weather conditions forecast for at least the next 7 days. Storms with locally heavy rainfall will focus over eastern NM today then across more of northern, central and western NM Friday. A ridge of high pressure developing to the north of NM over the weekend will spread drier air into northern and eastern NM thru early next week. The main focus for storms with heavy rainfall is likely to shift into southern NM during this time. High temps will gradually warm closer to normal as well. && .PRELIMINARY POINT TEMPS/POPS... Farmington...................... 57 87 58 87 / 0 20 5 0 Dulce........................... 44 82 44 81 / 20 40 30 20 Cuba............................ 51 80 50 81 / 20 40 40 20 Gallup.......................... 48 83 49 84 / 5 30 10 30 El Morro........................ 51 78 50 77 / 5 40 30 50 Grants.......................... 51 81 51 82 / 5 40 30 30 Quemado......................... 52 79 51 79 / 10 50 30 60 Magdalena....................... 57 77 55 78 / 10 50 30 40 Datil........................... 51 77 50 77 / 10 40 30 50 Reserve......................... 50 86 49 84 / 10 50 30 70 Glenwood........................ 61 89 60 88 / 10 50 30 60 Chama........................... 45 74 43 74 / 20 60 50 20 Los Alamos...................... 56 78 53 78 / 20 60 40 30 Pecos........................... 53 74 50 76 / 30 60 40 30 Cerro/Questa.................... 44 73 41 75 / 20 60 40 20 Red River....................... 44 64 41 65 / 20 60 50 20 Angel Fire...................... 37 67 38 70 / 20 60 40 20 Taos............................ 46 79 47 79 / 20 60 40 10 Mora............................ 49 71 46 73 / 20 70 40 30 Espanola........................ 55 86 53 85 / 20 50 40 20 Santa Fe........................ 55 78 53 76 / 30 60 40 20 Santa Fe Airport................ 54 82 52 82 / 30 50 40 20 Albuquerque Foothills........... 61 83 59 84 / 30 40 40 20 Albuquerque Heights............. 61 85 60 84 / 30 40 40 20 Albuquerque Valley.............. 60 87 58 86 / 30 40 30 10 Albuquerque West Mesa........... 62 87 60 86 / 30 40 40 10 Belen........................... 59 86 57 86 / 20 30 30 10 Bernalillo...................... 60 88 58 87 / 30 40 40 10 Bosque Farms.................... 58 86 56 85 / 30 40 30 10 Corrales........................ 60 87 59 87 / 30 40 40 10 Los Lunas....................... 59 86 57 85 / 30 30 30 10 Placitas........................ 59 83 56 83 / 30 40 40 20 Rio Rancho...................... 61 86 59 86 / 30 40 40 10 Socorro......................... 62 87 60 88 / 20 40 30 30 Sandia Park/Cedar Crest......... 54 76 50 77 / 30 50 40 20 Tijeras......................... 57 79 54 79 / 30 50 40 20 Edgewood........................ 53 77 49 78 / 30 50 30 20 Moriarty/Estancia............... 51 78 47 80 / 30 50 30 20 Clines Corners.................. 52 72 49 75 / 40 40 30 30 Mountainair..................... 53 76 49 78 / 30 50 30 30 Gran Quivira.................... 54 76 51 79 / 30 50 40 30 Carrizozo....................... 59 79 56 80 / 30 40 50 50 Ruidoso......................... 54 69 51 72 / 40 50 60 60 Capulin......................... 52 72 49 77 / 30 50 20 5 Raton........................... 53 77 49 83 / 20 50 20 5 Springer........................ 53 79 50 82 / 20 50 20 5 Las Vegas....................... 51 74 48 78 / 30 60 30 20 Clayton......................... 59 77 55 80 / 60 30 10 0 Roy............................. 56 75 53 78 / 60 40 30 10 Conchas......................... 61 81 59 83 / 70 50 30 10 Santa Rosa...................... 59 78 57 79 / 70 50 40 20 Tucumcari....................... 59 78 56 82 / 80 50 40 10 Clovis.......................... 63 78 60 84 / 80 70 50 40 Portales........................ 63 78 60 84 / 80 70 60 40 Fort Sumner..................... 63 81 59 84 / 80 50 50 30 Roswell......................... 68 83 65 86 / 60 70 70 50 Picacho......................... 60 77 58 78 / 40 70 60 50 Elk............................. 56 75 55 74 / 30 70 60 60 && .ABQ WATCHES/WARNINGS/ADVISORIES... Flood Watch until 8 PM MDT this evening for NMZ214-215-229. && $$ SHORT TERM...42 LONG TERM....77 AVIATION...53
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
850 PM EDT Thu Aug 29 2024 .SYNOPSIS... A backdoor cold front crosses the area this afternoon into tonight before stalling across southern portions of the area Friday. This will allow for scattered showers and storms from this afternoon through Friday. Another cold front brings unsettled conditions this weekend. Cooler and drier conditions eventually return early next week behind the second cold front. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 845 PM EDT Thursday... Key Messages: - A Flood Watch remains in effect from this afternoon through part of tonight for portions of the area from the Piedmont to Richmond and the Tri-Cities. Latest analysis reveals backdoor cold front bisecting the area from NW to SE at 00z. The front has cleared the eastern shore, RIC metro and tidewater areas, and will slowly drop SSW through the evening. While isolated convection has developed across the northern half of the area this evening, mainly on convective outflows and the front itself, the majority of convection has remained just north of the area in S MD and NoVA to DC Metro area. Past few runs of the HRRR have finally seemed to catch on to this trend, keeping a fairly strong signal for heavy rain across northern VA over to the eastern shore. Will keep the Flood Watch in place north of Richmond Metro (Louisa/Goochland/Caroline), where outflow from convective activity to the north will likely still allow for heavier showers and storms tonight. However, given convective trends, will let the Flood Watch go farther south. Along the coast, marine stratus and fog will persist along the Atlantic coast of MD/VA on the eastern shore, as well as the E VA coast. Lows tonight in the low- mid 70s expected under mostly cloudy skies. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... As of 355 PM EDT Thursday... Key Messages: - Continued unsettled but cooler on Friday with scattered showers and storms. - Hot and humid Friday through the weekend with heat indices of 100-105F possible across far S VA and NE NC Friday and 95-100F Saturday and Sunday. - Isolated to scattered storms are possible on Saturday, with the best chances along and west of I-95. The backdoor front stalls near or just south of the VA-NC border on Friday as upper heights continue to fall while the upper ridge continues to slowly break down and retreat to our south. Even though the front will be near our southern CWA border, there will be a decent amount of deep-layered moisture just behind it. As such, chances for scattered showers and storms will continue on Friday (highest during the afternoon/evening across S VA/NE NC). Isolated storms will be possible farther north (potentially to the Eastern Shore). Will also note that there is a decent HREF prob for showers/storms across the E side of the Eastern Shore Fri morning with locally heavy rainfall possible. Storms gradually taper off from NE to SW trough Fri evening. Given slow storm motions and a very moist environment (similar to today) as well as the stationary front nearby, we could be looking at another heavy rain/flash flooding threat Fri across S VA and interior NE NC. HREF probs show a 30% chance for 3"/3hrs across this area with even a small 50% chance across SW Mecklenburg. While no Flood Watch will be issued with this update (due to uncertainties in the front location with respect to how today plays out), a Flood Watch may need to be considered in future updates if the heavy rain signal increases. Otherwise, the chance for severe wx on Friday is low, but SPC does have extreme S VA and NE NC under a marginal risk (level 1/5) for a few damaging wind gusts. Highs Fri around 80F NE and around 90F S with most in the mid-upper 80s under mostly cloudy skies (some brakes possible in the afternoon). Dew points remain high (mid 70s for most). As such, heat indices of 100-105F are possible across S VA and NE NC with mid 90s across most of VA. The stationary front lifts back N as a warm front Fri evening into Fri night with highs in the upper 80s to the lower 90s Sat and Sun. Dew points remain in the 70s with heat indices of 95-100F each day (100-103F possible Sun across SE VA/NE NC). Lows in the upper 60s to lower 70s each night (most in the lower 70s). Isolated to scattered showers and storms are possible Sat, but confidence in coverage is relatively low (20-35% PoPs). The better chance for scattered showers and storms is Sunday afternoon into Sun evening as another cold front crosses from NW to SE. The entire FA is under a marginal risk for excessive rainfall Sun due to the potential for localized instances of heavy rain and flash flooding. Additionally, a few strong storms will be possible. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 400 PM EDT Thursday... Key Messages: - Cooler and drier weather is expected early next week (especially by Tuesday). The cold front crosses the area Sun night into Mon with a strong area of cold high pressure building in to the Great Lakes Mon and to the Mid Atlantic by Tue-Wed. As such, below normal temps return as well as drier conditions. Mon looks to be the warmest with highs in the low-mid 80s and a lingering chance for scattered showers and storms across far SE VA and NE NC through the afternoon. Highs in the upper 70s will be common Tue-Thu. Lows will also return to more pleasant values with temps in the mid- upper 50s inland most nights. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... As of 850 PM EDT Thursday... Cloud cover increases tonight with initially VFR CIGs inland and IFR/LIFR CIGs along the coast (due to a marine layer pushing inland). CIGs low-end MVFR at SBY become IFR this evening behind a backdoor cold front. Elsewhere, CIGs lower to MVFR and then IFR/LIFR overnight behind the cold front from NE to SW with all terminals IFR/LIFR by around 3-5z (apart from ECG, where IFR will take until after 07-09z and will be short-lived). The highest uncertainty is at ECG where IFR quickly improves back to MVFR then VFR Fri morning. CIGs eventually improve to MVFR by late Fri morning/early afternoon N terminals. Additionally, at least patchy fog near the coast this evening, spreads inland overnight into early Fri morning with MVFR/IFR VIS possible. This is a result of marine stratus and fog pushing inland late this evening. Outlook: Additional showers will continue to be possible along and E of I-95 Fri morning, potentially impacting SBY (perhaps to RIC/PHF). Scattered afternoon and evening storms will again be possible across S portions of the FA Fri afternoon into Fri evening (best chance at ECG). Winds were generally SE/E 5-10 kt this afternoon. Winds become NE behind the cold front this evening/overnight, becoming light late. Winds remain NE/E 5-7 kt Fri. MVFR-IFR CIGs likely recur Friday night into Saturday, with VFR conditions to gradually return by later Saturday morning into Saturday afternoon. && .MARINE... As of 330 PM EDT Thursday... Key Messages: - Small craft advisories in effect for the coastal waters N of Parramore Island and the Chesapeake Bay from this afternoon into tonight due to increasing NE winds and building seas. - Quieter conditions expected this weekend as the flow turns southerly. -Potential Cold front next Monday into Tuesday that could bring SCA conditions back to our coastal waters. This afternoon, a 1022mb high pressure is now well offshore to our SE, with an east-to-west oriented cold front located near the VA-MD boarder stretching along the potomac river. Southeasterly to easterly winds along the bay and NC coastal waters. Behind the coldfront winds have shifted to the northeast around 10-15 kt. Wave heights have begun to rise to 2-3 ft behind the cold front but remain 1-2 ft south of the front in the coastal waters and around 1 ft in the bay. The current forecast continues to have the front stalling just S of the NC/VA border in the later this evening. Behind the front, winds will turn to the NE and increase to 15-20 kt for the Chesapeake Bay and coastal waters N of the NC/VA border. Have continued the small craft advisory on the coastal waters N of Parramore Island through early Friday morning. These zones are most likely to see seas approaching 5 ft and this is primary reason for the SCA there. Have also added all of the Chesapeake Bay to the SCA for the 15-20 kt winds (gusts to 25 kt), starting at 20z/4 PM this afternoon. The higher winds will likely be rather short- lived in the bay; thus, the SCA only goes through 05z/1 AM Friday. Have left out the lower James given higher uncertainty, but this may need to be added in future updates. The front is also expected to spark tstms inland, though cannot rule out a few showers or storms spilling into the Chesapeake Bay tonight. Winds Friday will be lower, but onshore flow continues in the 10-15 kt range. Winds become southerly again for Saturday and Sunday as the front lifts back N through the waters, but wind speeds should be sub- SCA. Then by Monday model guidance suggest that a stronger cold front could pass through and the coastal waters will see northerly winds approach SCA levels behind it. Then by Tuesday a high pressure slides to the north bringing NE winds approach SCA levels once again. Seas of 4-5 ft are then expected by this evening N of the Parramore Island, with 2-3 ft elsewhere. 2-3 ft waves are also forecast in the bay from the late afternoon through early tonight. Seas slowly subside to 3-4 ft Friday and then 2-3 ft Saturday/Sunday. Waves/seas potentially increase again behind the front Monday/Tuesday. A moderate rip current risk is forecast across all beaches Friday and Saturday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...Flood Watch until 1 AM EDT Friday for VAZ048-060>062-064- 067>069-080-081-509>516. MARINE...Small Craft Advisory until 1 AM EDT Friday for ANZ630>632-634. Small Craft Advisory until 10 AM EDT Friday for ANZ650-652. && $$ SYNOPSIS...RMM NEAR TERM...ERI/MAM/RMM SHORT TERM...RMM LONG TERM...RMM AVIATION...RMM MARINE...HET/SW
Area Forecast Discussion
National Weather Service Boise ID
830 PM MDT Thu Aug 29 2024 .DISCUSSION...Lots of smoke in the air over much of the area today, and this smoke will extend west into eastern Oregon Friday. Otherwise, there are no clouds to deal with and winds will remain light. No update is needed at this time. && .AVIATION...VFR in most of Oregon at this time, with mostly MVFR/areas of IFR in ID due to smoke. Smoke will spread into eastern Oregon tonight. Smoke and MVFR continuing tonight through Friday. Surface winds: variable less than 10 kt. Winds aloft at 10kft MSL: variable less than 10kt. KBOI...MVFR visibility in smoke. Surface winds: variable around 5 kt, becoming SE around 5 kt after 29/06Z. Weekend Outlook...MVFR visibility with local IFR in smoke, with clear skies above through early Sunday. Increasing clouds Sunday. A slight chance (15%) of thunderstorms Sunday evening in southeast Oregon. Surface winds: variable less than 10 kt. Winds aloft at 10kft MSL: variable 5-10kt, becoming S 5-15 kt Sunday. && .PREV DISCUSSION... SHORT TERM...Tonight through Saturday night...A ridge of high pressure building over the area will bring dry weather and light winds to the area. Thick smoke from wildfires burning in the central Idaho mountains will continue to affect large areas of southwestern Idaho. The HRRR smoke model is correct in showing a huge production of smoke each afternoon which will later be trapped under a night time temperature inversion and then drain into the lower valleys overnight. Smoke may thin out a bit in the afternoons when atmospheric mixing improves, but new smoke will replace it overnight. The smoke will likely spread westward into Oregon as well, but is not expected to be quite as dense on the Oregon side. Temperatures will be a little hotter each afternoon reaching 10 to 15 degrees above normal by Saturday. Clear skies above the smoke layer will allow for excellent radiation cooling overnight with chilly morning lows expected...especially in the mountains. LONG TERM...Sunday through Thursday...Chance of showers and high- based thunderstorms in eastern Oregon Sunday as a Pacific upper low approaches southwest Oregon. Better chance of thunderstorms (20- 40%) Sunday night, Labor Day, and Monday night as the upper low moves northeastward across Oregon. Low should move across central Idaho Tuesday and into Montana Tuesday night. Better ventilation and showers may lessen the smoke. Cooler Tuesday, then warming and drying again the rest of next week as high pressure aloft rebuilds. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...SP AVIATION.....SP SHORT TERM...JB LONG TERM....LC
Area Forecast Discussion
National Weather Service Charleston SC
928 PM EDT Thu Aug 29 2024 .SYNOPSIS... High pressure will remain across the region through the weekend. A cold front could approach the region and stall in the vicinity early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... The main forecast challenge for the overnight period centers around the potential for fog and stratus. Conditions are largely unchanged from the past several nights. Abundant low- level moisture is in place with a deep, dry layer noted aloft on the 30/00z KCHS raob. The boundary layer has decoupled inland which will spread to the coast soon resulting in calm/light winds everywhere. Mostly clear skies and calm winds will promote fog development early Friday. 1000 hPa condensation pressure deficits are progged to remain fairly high per latest RAP output so any fog/stratus should remain fairly shallow. Confidence on anything outside of patchy dense fog remains pretty low at this juncture given these high condensation pressure deficit values. Fog with "patchy" and "areas of" qualifiers were maintained for this update with no explicit mention of dense fog. Lows will range from the lower 70s well inland to the upper 70s at the beaches and Downtown Charleston. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... High pressure aloft will be almost directly overhead on Friday, slowly retreating southwards towards the Gulf of Mexico Saturday and into Sunday. To the north a broad upper level trough will be positioned just to the west of the Great Lakes on Friday, slowly pushing eastward through the weekend. By Sunday afternoon an almost zonal flow will develop over the southeastern states as the high pressure retreats south and the mid-level trough swings eastward. At the surface high pressure Friday will be centered offshore, placing the local forecast area along the western periphery. This high pressure will slowly retreat into the Atlantic waters through the weekend as a weak cold front approaches the region late on Sunday. The strong upper ridging will keep warm and mainly settled conditions in place, with only limited shower/storm activity each afternoon. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A broader scale upper level low pressure will be located across the Great Lakes and New England region during the latter half of the weekend into early next week with suppressed heights down into the Mid Atlantic region. Meanwhile, at the surface, a boundary/cold front could eventually advance into the Carolina Midlands/eastern Georgia region by early next week then potentially advance offshore and stall by Tuesday, bringing the return of northeasterly flow and cooler temperatures to the region heading into the middle part of next week. Expect scattered to widespread showers and thunderstorms to mainly follow a diurnal trend as the front slowly approaches/crosses the region Monday and Tuesday. Strong ridging over the NE looks to ridge down the eastern seaboard later Tuesday through mid-week, with at least weak CAD taking shape. As such, general expectation would be below normal temps and more extensive cloud coverage, and perhaps enhanced shower activity, through the middle of next week. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... 30/00z TAF Discussion: KCHS/KJZI/KSAV: Fog/stratus will be the primary concern again tonight. Conditions favor another round of shallow ground fog and patchy stratus. High 1000 hPa condensation pressure deficits suggest the fog will remain quite shallow with any stratus that forms remaining fairly patchy. A mention of MIFG was maintained at all three terminals with TEMPO groups to address a brief period of MVFR vsbys. Any fog could mix out by 13z. Extended Aviation Outlook: Prevailing VFR, though some patchy/mainly shallow fog is possible early each morning through this weekend. && .MARINE... Tonight: Atlantic high pressure will extend across the region, yielding a weak pressure gradient across local waters. Given the pattern, expect south-southeast winds around 10 kt early this evening that gradually decrease to around 5 kt by midnight. Seas will range between 1-2 ft. Friday through Tuesday: Broad surface high pressure ridging from the Sargasso Sea across the Southeast will dominate over the marine zones through the weekend. Light to moderate south/southeasterly flow will remain across the coastal waters through Monday. Seas remain 1-3 ft in minimal SE medium period swell through this weekend as well. High pressure ridging down the eastern seaboard will tighten the gradient beginning Tuesday, and breezy NE flow through mid-week could eventually necessitate SCAs. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1006 PM EDT Thu Aug 29 2024 .SYNOPSIS... Hot and humid high pressure will remain across the region through the rest of the work week. The chance of showers and thunderstorms will slowly increase through the Labor Day holiday weekend. Temperatures will remain above normal through the weekend falling to below normal for the middle of next week as a cold front moves south of the area and cooler high pressure builds in from the north. && .NEAR TERM /THROUGH FRIDAY/... As of 1000 PM Thursday...Convection has waned across the forecast area, but a stray shower or two cannot be ruled out over the next few hours. Still some lingering debris clouds from earlier convection mainly in the western NC mountains that should dissipate overnight, allowing for the potential for mtn valley fog in the pre-dawn hours. Low temps will be seasonably warm once again, generally 3-5 degrees above normal. For Friday, a convectively active day is expected, which we haven`t had a lot of lately. The upper anticyclone over the Southeast will continue to break down further through the day and the guidance concurs that we should become normally unstable in the afternoon with CAPE at least 2000 J/kg. RAP fcst soundings also suggest sufficient dCAPE and weak shear for another pulse severe wet microburst threat. Almost the entire fcst area is in a Marginal Risk on the Day 2 outlook, so expect we will finally get some real action on the radar for a change. High temps should end up maybe a category less because of more cloud cover and shower activity earlier in the afternoon. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 200 pm Thu: An upper anticyclone will remain centered over the Southeast through Saturday, followed by falling heights/weakening of the anticyclone as a series of short wave troughs sweep across the northeast quadrant of the country. The large scale pattern is therefore expected to become steadily more favorable for convective development. Meanwhile, PWATs are expected to be AOA 1.75" through the period, while at least moderate destabilization is expected each afternoon. This is expected to result in good coverage (generally 60-70 PoPs) of diurnal convection across the mtns...and scattered coverage (mainly 30-50%) across the Piedmont and foothills both days. Wind fields/shear parameters will remain very weak in the vicinity of the upper high center...so any severe storm potential will be limited to perhaps a couple of pulse storms. Slow cell movement along with enhanced moisture should result in some potential for localized excessive rainfall. A slow cooling trend will otherwise continue, with temps generally expected to be 3 or 4 degrees above normal through the period. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 215 pm Thursday: The southern extent of a long wave trough is forecast to extend into the western Carolinas at the start of the period, with the leading edge of an attendant frontal zone expected to approach the CWA be early Monday. This should again enhance the deep convective potential above climatology for Monday, with a continued potential for locally excessive rainfall and perhaps a couple of pulse severe storms. After Monday, the forecast becomes more uncertain due to questions on how far the frontal boundary will push before stalling. The deterministic runs of the ECMWF and the GFS push deep dry air through the forecast area by mid-week. However, there are enough members of their respective ensemble suites...not to mention the Canadian deterministic run...that for one reason or another (primarily due to upglide precip developing atop the boundary) maintain precip potential through the end of the period to hold on to token chance PoPs through the end of the period. Regardless of the precip potential, conditions are expected to cool substantially during the extended, with temps forecast at 5-10 degrees below climo Tue through Thu. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: Convection should continue to wane across all the TAF sites this evening with some debris cloudiness lingering into the night. With more rainfall across the mountains today, expect a better chance of mountain valley fog, but confidence at KAVL remains marginal. Friday looks like an active day with PROB30 for TS warranted at all TAF sites. Winds will favor a S to SSW wind, but will be light and variable or calm overnight. Outlook: Diurnally active convective weather is expected each day thru Monday. That means some brief restrictions around storms in the afternoon/evening, then potential for fog development in the early morning hours where it rained each day. Drier air may push in from the north Tuesday, but some convective rain chances may linger. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JDL NEAR TERM...ARK/PM SHORT TERM...JDL LONG TERM...JDL AVIATION...ARK
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1130 PM EDT Thu Aug 29 2024 .KEY MESSAGES... - Record or near record high temperatures are forecast to continue into Friday. - A modest cool-down is expected for the weekend and beyond. - While showers and thunderstorms are possible Friday through Sunday, the greatest potential for rain is on Saturday. && .UPDATE... Issued at 1130 PM EDT THU AUG 29 2024 Made some minor edits to Sky grids to reflect latest trends, mainly in reducing cloud cover. Otherwise, the forecast is on track with no other substantive changes. UPDATE Issued at 819 PM EDT THU AUG 29 2024 This afternoon`s convection and resulting outflows, along with the loss of daytime heating, have resulted in the stabilization of the atmosphere over eastern Kentucky. Only a few sprinkles or light rain remain over far eastern parts of the forecast area, and these will quickly diminish over the next 1 to 2 hours. PoPs and Sky grids were updated to reflect these trends, with latest observations used as the initialization for for the evening and overnight temperature and humidity forecasts. && .SHORT TERM...(This evening through Friday night) Issued at 514 PM EDT THU AUG 29 2024 Late this afternoon, to the north of an upper level ridge centered in the southeast Conus, a weak frontal zone extended from coastal VA northwest to southeastern OH and then west near the OH River and eventually as a warm front associated with a low pressure system over the Manitoba to the upper MS Valley region. An upper level low associated with this low pressure system was centered near the Saskatchewan/Manitoba to ND border region with an upper level trough south across the northern to portions of the Central Plains and an additional shortwave moving across portions of the Rockies. Closer to home, a weak impulse/shortwave at 500 mb is also moving across portions of the mid to Lower OH Valley region around the southeastern U.S. ridge and likely contributing to convective development across the region. With a frontal zone in the vicinity of the OH Valley, isolated to scattered pulse showers and thunderstorms have developed. These stronger pulse thunderstorms especially those that have involved mergers have likely led to gusty winds and perhaps some small hail and this potential will continue this evening. MLCAPE is currently analyzed for areas outside of convection in the 1000 to 2000 J/kg range, with mid level lapse rates near 6C/km or less while low level lapse rate in those areas in the 8 to 9C/km range. This evening and tonight, the passing mid level disturbance will move toward the mid Atlantic coast while the axis of the upper level ridge centered in the southeast U.S. and extending into the Great Lakes will approach eastern KY. Further west, the upper level low is expected to track northeast toward far northwest Ontario and Hudson Bay with the trailing trough nearing the western Great Lakes to mid MS Valley region. At the same time, the parent sfc low is expected to track toward northwest Ontario and the Hudson Bay region as well. The frontal zone located in the OH Valley region near the area should lift northeast as this occurs into the Central Great Lakes region while the cold front nears the western Great Lakes and drops into the Southern Plains. For Friday and Friday night, the upper level low should continue northeast into Hudson Bay while the trailing upper level trough approaches and then moves into the Great Lakes to mid MS and Lower OH Valley region. Head of this, the cold front will move to the eastern Great Lakes and sag toward the OH River. Convection should diminish by late evening, though a stray shower or thunderstorm cannot be completely ruled out overnight per some convective allowing model runs. Valley fog along the larger creeks and area rivers should again develop by around midnight or not long after in some cases and increase in coverage overnight. This should affect some of the larger creeks, rivers, and area lakes and should again lift and dissipate by the 9 to 10 AM EDT timeframe. Cumulus develop on Friday as heating and mixing occur likely around or not long after noon per forecast soundings. Despite the surface frontal zone anticipated to have lifted north and northeast of eastern KY on Friday, isolated to scattered shower and thunderstorm activity may be focused in any leftover outflow boundaries from convection that occurs through this evening and in areas of differential heating. MLCAPE is forecast per the 15Z RAP to reach the 1000 to 2000 J/kg range on average Friday afternoon with shear again minimal. Pulse thunderstorms should again occur and with DCAPE again forecast by some guidance such as the RAP to be around 1100 J/kg on average if not higher in some areas, strong wind gusts cannot be ruled out. Mid level lapse rates 6C/km or lower may be a limiting factor again as far as coverage while low level lapse rates should peak at 8 to 9C/km and be favorable for gusty winds. A relative lull in convection may occur from late evening into Friday night. However, as the cold front nears and the upper level trough approaches and height falls are noted at 500 mb convection cannot be ruled out Friday night, especially further north and west. .LONG TERM...(Saturday through Thursday) Issued at 531 PM EDT THU AUG 29 2024 A pattern change will unfold over the weekend as near to record- setting August heat fades to a more seasonable early September brand of warmth. The 29/12z model suite analysis beginning Saturday morning shows a weakening ~591 dam high, centered over Georgia/Alabama, being shunted to the south as a trough, extending from the Central Plains/mid-Mississippi Valley northward to its ~533 dam parent low near/over far northern Quebec. At the surface, a cold front extends from an ~980mb low over/near northern Quebec southward to the Ottawa Valley and then southwestward across the Central Great Lakes, Ozarks and beyond into the Southern Plains. The aforementioned cold front will continue to sag southeastward on Saturday while a return flow advects and increasingly humid air mass across the Commonwealth (mean PWATs flirt with 1.90 inches in the LREF). Though spotty convection is possible early in the day, more widespread convection (70 to 80 PoP) is forecast to develop during the afternoon as the atmosphere destabilizes. With weak shear, anticipate mainly ordinary pulse-type thunderstorms. However, the NAM12/RAP13 suggest moderate SBCAPE values nearing or exceeding 2,500 J/kg along with sufficient DCAPE to support a few microburst/downburst events, thus isolated instances of damaging winds are certainly possible. It will still be quite warm with high temperatures forecast to range from the mid 80s to around 90. Convection is expected to wane on Saturday night as the cold front settles to along or just south of the Ohio River. The cold front will continue to make slow southeastward progress on Sunday, once again bringing the threat for widespread convection (80-90 percent chance) for locations along and southeast of the Hal Rogers/KY-80 corridor. Near and north of the boundary, maximum rain chances wane to 30 percent over northern Fleming County. High temperatures are forecast to range in the upper 70s to lower 80s, where rainfall will be most persistent, to the mid 80s north of I-64, where better sunshine is anticipated. The increasingly diffuse front will continue to sink south of the area on Sunday night with waning rain chances. Theta-e analysis suggests that a trailing secondary cold front will develop over the weekend and sag into eastern Kentucky on Labor Day before hanging up over or just south of the area. Drier air to oozes into northern Kentucky during the afternoon on northeasterly flow as surface high pressure passes through the Great Lakes. This will set the stage for a mostly sunny and comfortable holiday with highs in the lower 80s north and lower to middle 80s south. Dew points fall through the 50s and perhaps flirt near 50 north during the afternoon but remain in the lower 60s south. This will set the stage for a notable north-south temperature gradient on Monday night with lows falling deep into the 50s north (possibly upper 40s in the coolest valleys) but only in the upper 50s/lower 60s south. As the high pressure slowly shifts east from the Great Lakes to Northeast, weak surface lee troughing develops over the western foothills of the Central Appalachians as moisture seeps back north into the JKL forecast area. Consequently, weak disturbances passing in the cyclonic flow aloft may spark a stray shower (10 to 20 PoP) on Tuesday over far southern Kentucky. Slight chance to low chance PoPs are forecast across the CWA on Wednesday and Thursday, as the trough lingers. Expect high temperatures in the low to middle 80s on Monday/Tuesday and then upper 70s to lower 80s for most locations on Wednesday and Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 720 PM EDT THU AUG 29 2024 Shower and thunderstorm activity has diminished for the evening, so will remove any mention of such from the 00z TAF package. Light rain or sprinkles will continue until 00z or 01z toward KSJS, but with VFR conditions will leave out of the TAF. Expect IFR valley fog formation tonight, especially in areas that received appreciable rain this afternoon as well as the typically larger river valleys, but TAF sites are expected to remain fog-free as of the 00z TAF package issuance. Isolated thunderstorms are expected to develop Friday afternoon, but coverage is likely too low to warrant anything besides VCTS mention. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CMC SHORT TERM...JP LONG TERM...GEERTSON AVIATION...CMC
Area Forecast Discussion
National Weather Service Louisville KY
919 PM EDT Thu Aug 29 2024 .KEY MESSAGES... * Likely the hottest days of the summer so far now through Friday with near record heat each day. * Isolated storms possible through evening. Locally gusty winds possible from microbursts. * Cold front will move through the region late this weekend, bringing relief from hot temperatures and humidity. && .UPDATE... Issued at 919 PM EDT Thu Aug 29 2024 Convection has largely diminished across the region and skies are beginning to clear out. Temperatures across the region varied from the mid-upper 70s in areas that received rainfall this afternoon, to the the lower 80s in the I-65 corridor and points west. The urban heat island in Louisville metro is still around 90 this hour. For the overnight period, quiet weather is expected. Temperatures will drop into the 70s for lows. Could see some patchy fog over in southern Indiana where dewpoints are a little higher. Also could see some locally patchy fog over in the Bluegrass region where ample rainfall fell this afternoon. && .SHORT TERM /THROUGH FRIDAY/... Issued at 320 PM EDT Thu Aug 29 2024 Diurnally driven storms have popped across the Bluegrass, with gusty wind potential being noted in those areas. Will continue to see microburst potential with any stronger core aloft given the steep low level lapse rates, inverted V (dry low levels) signature on soundings, and overall high DCAPE values (1100-1400 J/KG) as a result of those features. Elsewhere, the cu field is more sporadic, although agitated. Hi res HRRR continues to show isolated coverage this afternoon over the whole CWA, so can`t rule out additional coverage in those areas, although it may take remnant outflow from upstream activity as a trigger. Given the lack of deep layer shear, any storm this afternoon and early evening will be slow moving. Locally heavy rainfall is possible for anywhere that a storm sits for too long. Outside of the PM storms, temperatures are hot with values peaking in the 95 to 100 degree range. A few records have already been broken today, including SDF at 100 degrees so far. See the Climate Section of this AFD for more info. Clear calm conditions expected overnight after diurnally driven convection dies off. Could see some patchy fog in spots, especially over southern IN where dew points will be a bit higher. Friday brings one more hot day ahead of the approaching cool front. As a result, looking for another day of mid to upper 90s, with slightly higher dew points, especially along and west of I-65. Still HI values should hold around 100 at max, shy of any needed headline criteria. Expect to see isolated to widely scattered showers and storms develop by afternoon into the evening, most notably along and west of I-65 as the upper ridge begins to break down a bit. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Issued at 320 PM EDT Thu Aug 29 2024 Definite pattern change coming this weekend as a cool front stalls out over the region with slow-moving upper trough crossing the Great Lakes area Saturday. As that front washes out over the region, the pool of moisture associated with it will be slow to scour out. Thus, despite the current dry spell we`ve been in, we actually have some good rain chances both Saturday and into Sunday...though the more widespread higher amounts would look to be Saturday. Sunday`s chances look better the farther south and east you go, as by afternoon there should be a tight precipitable water gradient. NAM/GFS both show around 2" in the Lake Cumberland region and around 1" along the Ohio River. By Sunday night, the trough axis aloft will be shifting east of the region and surface winds should have enough of a northerly push to dry us out for the start of the next work week. Above normal low temperatures for the weekend should down to near or just below normal for the work week. High temperatures each day should be around normal..first under weekend cloud cover then with the drier air coming in. By mid week, we start to see moisture increase with some weak perturbations possibly allowing for pulse diurnal convection Wed/Thu. && .AVIATION /00Z TAFS THROUGH 06Z SATURDAY/... Issued at 714 PM EDT Thu Aug 29 2024 VFR conditions will continue through the upcoming TAF period. Afternoon convection has diminished in the last 30 minutes, but there are quite a few mesoscale outflow boundaries moving across north-central Kentucky (in particular the KSDF area). Mid-level capping has kept convection across north-central KY in check this afternoon and CINH will continue to increase as we go further into the evening. Nonetheless, can`t rule out some additional convection along the convergence of outflows near KSDF for the next hour or so. Elsewhere, VFR conditions with light winds are expected this evening and into the overnight. Some patchy fog may develop out toward KHNB after 30/10Z. The outlook for Friday calls for VFR conditions with southwesterly surface winds. && .CLIMATE... Issued at 320 PM EDT Thu Aug 29 2024 ================== Near-Record Heat This Week ================== Friday 8/30/2024 Max T Fcst/Record (Year) Louisville: 99/98 (1953) Bowling Green: 97/99 (1993) Lexington: 98/97 (1953) && .LMK WATCHES/WARNINGS/ADVISORIES... KY...Air Quality Alert until midnight EDT tonight for KYZ029>031. IN...Air Quality Alert until midnight EDT /11 PM CDT/ tonight for INZ076>079-083-084-089>092. && $$ UPDATE.......MJ SHORT TERM...BJS LONG TERM....RJS AVIATION.....MJ CLIMATE......BJS/SRM
Area Forecast Discussion
National Weather Service Marquette MI
648 PM EDT Thu Aug 29 2024 .KEY MESSAGES... - Quick round of showers and storms tonight into Friday. Low chance (~5%) for damaging wind gusts over the far west. - Breezy west winds, gusting up to 30 mph in the Keweenaw on Friday. - Cold front brings a brief round of showers and storms with gusty wind potential Saturday night, followed by breezy, cool conditions on Sunday. - Low end northwest gales expected late Saturday night and Sunday morning across the east half of Lake Superior. && .SHORT TERM /THROUGH FRIDAY/... Issued at 411 PM EDT Thu Aug 29 2024 Current RAP analysis has mid level ridging centered over the western Great Lakes with sfc high pressure situated over Quebec, extending southwest into the Great Lakes Basin. This has, and will continue to keep the UP dry through early this evening. Upslope southeast flow off Lake Michigan has continued the broken low level cloud deck, but this is expected to diminish into this evening. Temperatures the rest of this afternoon should hold fairly steady in the upper 60s to mid 70s, warmer over the west where there is clearer skies and downsloping flow. The main feature to focus on for the short term forecast is the trough currently centered over the Saskatchewan/Manitoba province line with it`s associated sfc trough and occluded/cold front draped south over the Dakota/MN state line. Tonight through Friday, the mid level trough lifts northeast through northern Ontario toward Hudson Bay. This sends the sfc trough and cold front eastward across the UP, forcing a round of showers and storms ahead of it. There is fairly good agreement in the CAMs of this QLCS over northwest WI and western Lake Superior this evening entering the west around 10-11pm EDT as it begins to fall apart. From there the round of showers and storms move into central Upper MI around 4am EDT and into the east around 5-8am EDT. The timing of this front is not ideal for strong to severe storms given the loss of diurnal heating. If the line is able to make it into the UP before breaking apart, HREF mean MUCAPE to ~1000 J/kg and bulk 0-6km bulk shear around 25-30 kts mean the storms could be strong to severe storms. The main threat would be some isolated damaging wind gusts. PWATs increasing up to around 1.8", the 99th percentile of the climatological NAEFS, and steep warm cloud depths could support some heavier downpours up to 0.5-1". Otherwise lows are expected in the low to mid 60s. By Friday the cold front will be situated over the central UP with showers and storms over the east half continuing eastward toward Ontario. Instability will be minimal by this point so strong to severe storms are not expected. Clearing skies follow behind the cold front as drier air intrudes from the west. Friday then warms up into the 70s with low 80s possible in the south central. Breezy winds are expected in the Keweenaw, gusting up to 30 mph. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Issued at 446 PM EDT Thu Aug 29 2024 Medium range ensembles today are in excellent agreement on the large scale flow changes that occur thru next week. Very well-defined mid- level low that is currently centered over far sw Manitoba will lift ne, reaching Hudson Bay Fri aftn. Ridging will then begin to build modestly over western Canada, and this in turn will force the next shortwave over s central Canada to drop se, modestly amplifying the weak troffing that initially reaches the Great Lakes by the preceding mid-level low. The trof amplification will occur over the Great Lakes Sat night/Sun. This trof then quickly lifts out to the ne early next week as positive height anomalies rapidly spread e across the southern half of Canada, setting up temporary low amplitude/nearly zonal flow across the southern half of Canada. Late next week, at least some degree of flow amplification will likely occur as western ridging builds, forcing troffing into the eastern U.S. For Upper MI, this evolution of the flow will bring a warm day on Sat ahead of the cold front associated with the shortwave dropping toward the northern Great Lakes. A much cooler day will follow on Sun. Slight moderation will occur on Labor day, then warming more firmly gets underway as low amplitude/nearly zonal flow quickly spreads across southern Canada. Temps should rise to 5 to 10F above normal by midweek. Some cooling should be favored late week or over the Sep 7/8 weekend, depending on degree of potential pattern amplification. As for pcpn, passage of the cold front Sat night will bring a quick round of shra/some tsra to Upper MI Sat night. Following shot of cool air may support a few lake effect -shra during Sun morning under breezy nw low-level flow. Dry weather will then overall prevail next week. There remains a weak signal that the onset of waa early next week as eastern trof lifts out may offer a less than 20pct chc of some shra around Tue. Next better chc of shra should hold off until late week when pattern potentially begins to amplify. Beginning Fri night/Sat, nothing more than sct to perhaps bkn at times high clouds are anticipated during this time. A seasonable night with lows from around 50 to the lower 60s Fri night will be followed by a warm day on Sat under w to sw winds ahead of next cold front approaching from the nw. Expect highs mostly in the upper 70s to lwr 80s F with dwpts comfortable in roughly the 50-55F range for much of the area. Will be on the breezy side Sat under deep mixing that could tap 30kt winds, particularly across western Upper MI. Vigorous shortwave dropping se into the northern Great Lakes will send associated cold front across Lake Superior and Upper MI Sat night. Decent forcing with sharp cold front will likely support a narrow band of shra/some tsra along the front despite rather limited moisture. Dry subcloud layer and 850mb winds ramping up to 40-50kt just ahead of front suggest gusty winds in excess of 45mph may accompany some of the shra. Given the holiday weekend and nice weather preceding thru Sat aftn, will be something to monitor as the shra arrive over nw Upper MI around 00z and then quickly spread se. 850mb temps tumble from 15 to 16C ahead of the front early Sat evening to 4-6C Sun morning. With buoys indicating water temps ranging generally from 16 to 20C, isold post-frontal nw flow lake effect shra will be possible Sunday morning. Incoming dry air mass and anticyclonic flow associated with high pres building se into the northern Plains/Upper Mississippi Valley will limit coverage and potential, but still worthy of schc (~20pct) mention. The cooler air mass will setup a breezy day across the fcst area. Fcst soundings suggest gusts 25-35 mph near Lake Superior/Keweenaw and 20-25 mph elsewhere. Even if -shra don`t occur, should see quite a bit of cloud cover blossom for a time under incoming 850mb thermal trof. Expect highs in the 60s, but the s central should reach 70F. If sfc high pres ends up over Upper MI Sun night or Mon night, would expect a chilly night with frost potential in the interior. For now, it doesn`t look like we`ll get a perfect radiational cooling night, but some patchy frost is a possibility. Sun night may end up as the coolest night. High temps will moderate on Labor Day and temps will return to well into the 70s for Wed/Thu under dry weather. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 648 PM EDT Thu Aug 29 2024 Generally VFR conditions prevail through this evening. A quick round of showers and some storms makes their way through tonight into Friday morning, bringing MVFR restrictions to IWD and CMX first and to SAW a hour or two later. Cigs at SAW look to drop down to IFR late tonight/early Friday morning. Best window for showers is between 2-6Z at IWD, 4-9Z at CMX, and 6-12Z at SAW. Expect conditions to improve into Friday morning as skies clear behind the cold front. Otherwise, gusts approaching 30 kts are possible on Friday at CMX. && .MARINE... Issued at 446 PM EDT Thu Aug 29 2024 Approaching cold front will cross Lake Superior overnight thru Fri morning. Ahead of the front, E to SE winds will gust 20-30kt tonight with the strongest winds probably in a zone from around Stannard Rock to Passage Island. Internal probabilistic guidance suggests a 10-30% chance of peak gusts reaching low end gales with the highest of these values along the International Border. Showers and thunderstorms will also move across the lake and may add to the gustiness of the ongoing winds, particularly over the western lake. Winds shift WSW to W with frontal passage, and the stronger winds shift to western Lake Superior for Fri. Internal probabilistic guidance indicates a 10-30pct chc of peak gusts reaching gale force btwn Isle Royale and nw Upper MI. Winds across eastern Lake Superior will settle back to around 20kt on Fri. Winds diminish Fri night and Sat morning to around 20-25kt between Isle Royale and the Keweenaw and remain 20kt or less elsewhere. Next cold front approaches from the nw on Sat. Ahead of the front, expect sw winds to again gust to 25-30kt over western Lake Superior in the aftn. Winds across eastern Lake Superior will be under 20kt. The cold front will sweep se across Lake Superior Sat night. A cool air mass following the front will lead to better mixing of higher winds down to the lake sfc for Sun. Incoming pres rises will also aid stronger winds. Probabilistic guidance continues to indicate a 60- 80% chc of low end NW gale force gusts across the e half of Lake Superior late Sat night/Sun morning. Winds begin to diminish from w to e Sun aftn and will fall to under 20kt for Mon/Tue as sfc high pres arrives over the western Great Lakes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Jablonski LONG TERM...Rolfson AVIATION...07 MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
627 PM CDT Thu Aug 29 2024 .KEY MESSAGES... - Near record heat this afternoon with high temperatures around 100 degrees. While temperatures will be a few degrees cooler on Friday, an increase in moisture will cause heat index values to be hotter near 105 degrees. - A slow moving cold front will bring the chance of showers and storms on Friday. More numerous scattered activity arrives Friday night with rain chances continuing through Saturday, and possibly Sunday. - Much cooler air arrives over the weekend, with less humid conditions in time for Labor Day. The next chance of rain arrives by the middle of the week. && .UPDATE... Issued at 626 PM CDT Thu Aug 29 2024 Updated Aviation discussion for 00Z TAF Issuance. && .DISCUSSION... Issued at 228 PM CDT Thu Aug 29 2024 Today is certainly turning out to be quite the hot day as the PAH ASOS is 101/61 at this hour! WPC sfc analysis currently shows a frontal boundary lifting north of the FA as a warm sector regime is now setting up with upper level ridging. A stray shower or storm still remains possible this afternoon, but any pcpn will quickly diminish with the loss of differential heating. An influx of moisture will advect north across the lower Ohio Valley on Friday causing dewpoints to rise into the low to mid 70s. Did lean closer to the NBM 90th percentile as model soundings are more saturated compared to today inhibiting the mixing potential. MaxTs will also be a bit cooler in the lower 90s due to the increase in moisture. This will still translate to higher heat index values between 100-105 degrees across much of the FA. It is probable that a few locations will briefly reach Heat Advisory criteria, but due to the short duration and limited spatial coverage, will hold off on issuing any headlines. As a cold front slowly moves southeast across Missouri in the afternoon, a 500 mb shortwave will transverse towards the FA by Friday evening providing forcing for ascent. Many of the 12z CAMs including the HRRR do not support much in the way of CI until Friday evening while a few outliers such as the ARW has CI occurring in the afternoon. Given the lack of upper level forcing, meager effective bulk shear below 20 kts, and potential inability to reach the convT in the upper 90s, have trended PoPs downward through the day compared to the NBM. Should a few isolated pulse storms develop, a brief gusty stronger storm would not be out of the question given MLCAPE between 1500-2500 J/kg and steep low-level lapse rates around 7.5-8.0 C/km. In the wake of fropa associated with the aformentioned cold front, more scattered convection is likely Friday night into Saturday as sfc convergence increases. While stronger storms will not be a concern with these due to waning instability, localized excessive rainfall cannot be ruled out due to a slow storm motion around 15-20 kts. FFG in the 3-4 inch range should limit the flash flooding potential on a synoptic scale, but the drier soil conditions will favor typical run off and poor drainage issues on roadways. Overall, QPF is only progged in the 0.50 to 1.50 inch range for most locations. With that said, a few lingering showers remain possible on Sunday, especially across southern portions of the FA. Drier air will then begin to advect in from the north as a trough digs across the Great Lakes region with a ~1026 mb sfc high pressure building south from Canada. This means more comfortable conditions are store by Sunday night into Labor Day as dewpoints will return to the lower 60s and even upper 50s. Temps will be slightly below normal with maxTs progged in the low to mid 80s and lows ranging from the upper 50s to lower 60s. As sfc high pressure slides east, there is some uncertainty in how quickly moisture returns from the south towards the middle of the week. Most of the deterministic models keep the FA dry, but some of the ensembles including the GEFS are a bit more aggressive in bringing in low pcpn chances by Tuesday. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 626 PM CDT Thu Aug 29 2024 Other than some patchy fog offering the possibility for vsby restrictions pre dawn, it`ll be another Visual Flight Rules forecast with mainly high based diurnal cu again tmrw. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...Air Quality Alert until 11 PM CDT /midnight EDT/ this evening for INZ081-082-085>088. KY...None. && $$
Area Forecast Discussion
National Weather Service Pocatello ID
203 PM MDT Thu Aug 29 2024 .SHORT TERM...Tonight and Friday. Dry and calm conditions will remain in place across central and eastern Idaho. With decent inversions in place, we do expect colder valleys to be in the 20s to lower 30s...just a bit warmer than last night. We will continue to see 40s and even some 50s tonight within the inversion layer. Highs Friday should finally push back to around or just above average for the end of August. Expect another wash, rinse, repeat night for Friday night...warming up a few more degrees vs tonight. Keyes .LONG TERM....SATURDAY THROUGH NEXT THURSDAY... A ridge of high pressure will remain in control through at least Sunday morning...if not Monday morning...slowly drifting east with time. This will support quiet, clear to mostly clear conditions across SE Idaho with very light winds and no precipitation, although varying degrees of wildfire smoke/haze will likely continue to be noticeable. Outside of the smoke and any attendant air quality impacts, nice late-summer days are expected! While some model guidance hints at a very low chance of a shower or t-storm Sunday afternoon, Monday is the more likely day where we`ll begin to feel the effects of our next approaching low pressure system in the form of a modest wind increase and daily chances of showers/t-storms, lasting at least through Tuesday evening everywhere if not lingering Wednesday in eastern portions of the CWA. Overall impacts (wind, QPF amounts, etc.) seem relatively modest with this next system so far...a look at 500mb height cluster analysis shows good agreement in the evolution of this feature with very weak EOF patterns, only 1 ensemble QPF cluster (15% of the ensemble space) advertises noticeably heavier QPF, and no organized response is evident in the ECMWF Extreme Forecast Index (EFI) for any weather element. All of this points to overall good forecast agreement at this juncture with no strong alternate forecast scenarios/concerns really emerging at this time. High temps will continue to top out in the 80s to low 90s leading into this system, before we see a modestly noticeable drop into the upper 70s and low 80s on Tuesday and Wednesday (although with continued precip chances as the through works through). Long- term model solutions diverge by late next week with anything from a ridge of high pressure (63% cluster support) to another low pressure storm system (36% cluster support) possible. - KSmith && .AVIATION...A ridge of high pressure will build into the Great Basin and northern Rockies over the next several days, supporting clear skies, very light winds, and no precipitation through at least Sunday morning, if not Monday morning. The only aviation impact we`ll be monitoring is smoke and haze, especially from the Wapiti Fire west of Stanley. Varying degrees of mid-level smoke/haze are evident on satellite and being observed visually today, but so far this has not resulted in any deviations from SKC and P6SM at TAF sites outside of KSUN, and we have no confidence that any significant degradations will occur over the next 24 hours, thus places like KBYI and KPIH remain VFR for now. Vsbys dropped as low as 1 1/2SM this morning at KSUN with smoke manifesting as a "cloud deck" up near 4,000 feet AGL as well, but vsbys have improved rapidly coincident with the diurnal wind shift at 17z/11am...quicker than originally advertised in the 18z TAF. Confidence is very low in how impacts from smoke will evolve over the next 24-36 hours, but for the TAF, we have mimicked what happened today with slight improvements but continued HZ through the afternoon/evening, another vsby drop overnight with NW down-valley flow drawing more smoke southward from the fire region, and then fairly quick improvement again between 17-19z/11am-1pm Friday when winds shift into the SE. This general concept has perhaps a hint of broad support from the HRRR smoke model, but again confidence is low and we`ll have to monitor trends closely. KBYI is perhaps the next best candidate for some slightly reductions in vsby at the sfc, but confidence is too low to add any impacts to their TAF at this time. By either Sunday afternoon or Monday afternoon, winds and shower/thunderstorm chances will start to increase again ahead of our next low pressure system. - KSmith && .FIRE WEATHER...Dry conditions will persist until we get to the back end of the Labor Day weekend. Dry air will keep poor overnight recovery in place. We are even expecting some valley locations, where we might see downslope/downvalley flow help keep the air from settling too much, only recovering to the 20-40% range. Single digit and teen relative humidity values will remain the norm as well. We should see enough monsoon moisture for isolated dry storms by Sunday afternoon. The better chance of rain and thunderstorms arrive for Labor Day and Tuesday. Keyes && .AIR QUALITY...A large area of smoke mainly due to the Wapiti Fire continues to encompass portions of central and eastern Idaho. The smoke has been thinning and shifting south and west due to flow in between the low over south-central Canada and high pressure to southwest. It does appear the thicker smoke will eventually pivot west and eventually to north based on the flow in the next 24-48 hours. This would keep the worst over the central mountains and shift it toward Lemhi County and southwest Montana. Other areas will likely some amount of smoke, but the to a lesser extent. We currently have AIR QUALITY ADVISORIES for Custer and Blaine Counties, and both are in effect through tomorrow. Keyes && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Salt Lake City UT
259 PM MDT Thu Aug 29 2024 .SYNOPSIS...Dry air will lead to clear skies through Friday with light and variable winds, along with wildfire smoke across northern Utah and SW Wyoming into Saturday. Moisture increases slightly across southern Utah by the weekend with isolated high- based convection possible during the afternoon Saturday and Sunday. Temperatures will gradually warm through the weekend and rise to 5-15 degrees above normal for Labor Day Weekend. && .SHORT TERM (Through 12Z/6AM Saturday)...Early afternoon Thursday, a strong area of low pressure was located over southern Manitoba, while a ridge of high pressure was building into the Western Great Basin. Cool early morning temperatures across northern Utah and SW Wyoming were giving way to high temperatures near to slightly below normal across the north, to near to slightly above normal across the south for late August. Behind the front, west to northwest winds will allow for central Idaho wildfire smoke to gradually drift southward into northern Utah and southwest Wyoming through this evening, with increasing haze and decreasing visibility and air quality. HRRR smoke model suggests this smoke will continue advecting southward into portions of central Utah on Friday, while gradually becoming more diffuse as we head through the weekend. See Utah DEQ for the latest air quality forecasts. Heading through the remainder of the period, the above-mentioned Western Great Basin ridge will build across Utah by Saturday morning. This will favor gradually increasing temperatures through the weekend with a return to above normal temperatures. Moisture will begin to gradually increase across southern Utah as well through the period, with afternoon terrain-based cumulus today giving way to a high-based shower or thunderstorm or two by Friday afternoon. This coverage will gradually increase through the weekend. .LONG TERM (After 12Z/6AM Saturday), Issued 305AM MDT... By the weekend, the center of the ridge of high pressure over the Intermountain West will begin to shift east of our area, allowing for mean southerly flow aloft (particularly over southern Utah). This will bring increased moisture into the area, although much less significant than recent monsoon surges. Global ensemble PWATs range from 0.4 to 0.6" across the area for the 25th-75th percentile by Sunday. For comparison, recent monsoon events featured PWATs of 1-1.3". Model soundings also show meager instability and with thin CAPE profiles high above the surface and dry low levels, suggestive of high-based showers and perhaps thunderstorms. Thus, the main threat with any convective development will be gusty winds. Such convection will initially be limited to southern Utah mountains Saturday, spreading northward and eventually including all higher terrain areas by Monday, with isolated to scattered coverage of weak storms. Meanwhile, a warming air mass will result in temperatures climbing through the weekend, peaking Sunday/Monday at 5-10 degrees above normal for most locations. HeatRisk for the Labor Day holiday shows a few pockets of orange, or moderate risk, but mostly limited to unpopulated West Desert locations. Looking ahead to next week, ensembles are in fair agreement with a closed low moving onshore somewhere between NorCal and the Pacific NW and (temporarily at least) flattening the ridge overhead of our area. Depending on how close the low is to our area, we could see elevated winds and perhaps a convective threat, though the most favored solution in ensembles (around 70% of the solution space) holds the low too far to our northwest to have much impact. At the very least, temperatures will subside by a few degrees as the ridge flattens. Thereafter for the remainder of the week, ensembles are in high agreement with mean ridging over the entire Western US and thus continued above normal temperatures. && .AVIATION...KSLC...North to northwest winds to remain in place until 04-05Z when typical southerly drainage flow is most likely to develop. This is slightly delayed compared to a normal evening thanks to a northerly pressure gradient. Increasing haze beginning this evening due to wildfire smoke from Idaho, resulting in potentially minor VIS reductions through Friday morning. .REST OF UTAH AND SOUTHWEST WYOMING...Wildfire smoke will gradually overspread northern Utah and SW Wyoming through this evening while spreading further southward into portions of central Utah during the daylight hours Friday. Greatest potential for VIS reductions is forecast to be generally along/north of a ENV-OGD- EVW line, with a few pockets of horizontal visibility reductions down to as low as 4-5SM along with a thin, opaque layer of smoke. Otherwise, expect mainly light, terrain-driven winds. && .FIRE WEATHER...A cold front has grazed across northern Utah on Thursday, bringing a cooldown while maintaining low humidity. Some smoke will drift into northern Utah from central Idaho fires as well, and persist across the north into Saturday. Overall though, conditions remain tranquil Thursday. Meanwhile, a ridge of high pressure will gradually build into the area through the weekend, bringing a gradual warming trend and a return to hot temperatures by the end of the weekend, when temperatures will reach 5F to 15F above normal for early September. Just enough moisture will return to southern Utah this weekend to support isolated, mainly high-based showers and thunderstorms. Winds will be primarily terrain-driven except near shower and thunderstorm outflow. Early next week, mainly in the Monday and Tuesday timeframe, an area of low pressure will move from northern California through Idaho. This will draw increased moisture northward across the state by Monday thanks to increasing southwest winds, bringing both some RH recovery along with a statewide chance of high-based showers and thunderstorms. As the low moves eastward by the middle of next week, it will force the flow to turn more westerly while dragging a weak cold front across northern Utah, resulting in a modest cooling trend while simultaneously scouring moisture out of the area. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ ADeSmet/Van Cleave For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
745 PM EDT Thu Aug 29 2024 ...New UPDATE, AVIATION... .UPDATE... Issued at 745 PM EDT Thu Aug 29 2024 No changes made to existing forecast package. Somewhat less active overall this afternoon and evening, however a few areas saw heavy rainfall and gusty winds that prompted a few statements. Remaining convection largely limited to offshore waters, with a low chance of a stray shower lingering through the evening before mostly clear to partly cloudy skies tonight. Repeat evolution likely on Friday, with afternoon and early evening showers and storms and highs in the lower to mid 90s. && .DISCUSSION... Issued at 204 PM EDT Thu Aug 29 2024 Broad surface high pressure centered between Bermuda and the Bahamas continues to ridge west-southwest across Florida and into the Gulf of Mexico. This synoptic pattern will keep Florida in a predominant easterly wind flow through the week and into the weekend. This will favor late afternoon/evening showers and storms forming along both the east and west coast sea breeze boundaries. Abundant moisture with PWAT values ranging between 1.6-2.1 inches will support scattered to numerous showers and storms each day with the highest chances over southwest Florida. Latest radar is showing these storms currently over the central and southwest part of the state and will continue moving westward through the day. The latest HRRR guidance has the bulk of these showers and storms over the west coast of Florida between 2-5 pm later today moving from east to west. Some of the stronger storms could produce gusty winds and localized flooding in low lying areas. Seasonal temps are also expected with highs in the low to mid 90`s and overnight lows in the 70`s. Heat indices will reach 102-107 each afternoon. The National Hurricane Center is keeping a close eye on an area in the central Atlantic that has a 40 percent chance of development through 7 days. We will be closely monitoring this system over the next week for further development. && .AVIATION... (00Z TAFS) Issued at 725 PM EDT Thu Aug 29 2024 Similar evening underway with diminishing convection, therefore held VCSH to open the cycle although that may be generous, however VFR expected into Friday afternoon when convection with the E FL sea breeze initiates and pushes west within the easterly flow over the peninsula, bringing a window of MVFR/IFR chances mid-late afternoon into the evening before returning to VFR evening into overnight. && .MARINE... Issued at 204 PM EDT Thu Aug 29 2024 Easterly winds around 10-15 knots will be in place across the waters through the period, with a weak sea breeze possible near the coast each afternoon. Showers and storms will be most likely in the late afternoon and evening pushing offshore from land. No headlines are expected. && .FIRE WEATHER... Issued at 204 PM EDT Thu Aug 29 2024 High pressure to the north ridges across Florida keeping a predominant easterly wind flow across the region. Scattered to numerous showers and storms can be expected each day through the week and into the weekend. No fire weather concerns are expected. && .PRELIMINARY POINT TEMPS/POPS... TPA 76 92 76 92 / 40 50 10 70 FMY 76 94 76 91 / 30 70 30 90 GIF 75 93 75 93 / 30 60 10 80 SRQ 75 94 75 92 / 40 50 20 70 BKV 73 94 73 93 / 40 50 10 60 SPG 80 93 79 93 / 40 50 20 70 && Sea Breeze Thunderstorm Regime For Friday: 2 Sea Breeze Thunderstorm Regime For Saturday: 2 For additional information on sea breeze regimes, go to: https://www.weather.gov/tbw/ThunderstormClimatology && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ UPDATE/AVIATION...Hurt DISCUSSION/MARINE/FIRE WEATHER...Wynn DECISION SUPPORT/UPPER AIR/CLIMATE...Delerme