Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/10/24


Area Forecast Discussion...CORRECTED
National Weather Service Boise ID
857 PM MDT Fri Aug 9 2024 .DISCUSSION...A weak shortwave is moving over the Pacific NW this evening and will track across WA, northern ID and into western MT by Saturday afternoon. As this moves through, there will be enough instability to trigger isolated thunderstorms generally north of a line from Burns OR to Jerome ID on Saturday. Updated the forecast to add mention of isolated thunderstorms in these areas early Saturday morning into Saturday afternoon. Gusty winds and lightning main threats with these storms. Drier air will move into the area on Sunday, before a trough over SW Canada begins to move south along the WA coast. This trough shifts the flow to the southwest, allowing monsoon moisture to move north into northern NV along the ID border, with isolated thunderstorms south of the Snake Basin on Sunday evening. && .AVIATION...Mostly VFR with areas of MVFR and local IFR near wildfires. Patchy mountain obscuration. Chance of showers and afternoon/evening thunderstorms north of KBNO-KBOI-Fairfield Saturday. Surface winds: variable 5- 10kt overnight. Gusty erratic outflow winds possible from showers and storms. Winds aloft at 10kft MSL: SW 5-15 kt. High density altitude 18Z-03Z. KBOI...VFR with potential for occasional MVFR from smoke. Surface winds: variable around 5 kt through Sat/18Z. High density altitude 18Z-03Z each day. Weekend Outlook...Mostly VFR with areas of MVFR and local IFR near wildfires. Dry Sunday. High density altitude 18Z-03Z. && .PREV DISCUSSION... SHORT TERM...Tonight through Sunday night...Near-surface smoke retreated from the Treasure Valley this morning but returned on north-northwest winds early this afternoon. HRRR smoke model keeps smoke in through midnight but then retreats again overnight and Saturday morning on southeast winds. The process repeats Saturday but less smoky than today, and again Saturday night but less smoky than tonight. Model consensus continues a 30-40 percent coverage of showers and isolated thunderstorms tonight along the eastern edge of our CWA, then a 40-60 percent chance of showers and afternoon thunderstorms in the same areas Saturday as an upper trough passes by to the north. Clearing and drying Saturday night and Sunday. Tonight looks cooler than last night in central and southern areas due to less cloud cover. Max temps Saturday and Sunday will average 2-4 degrees above normal, with min temps close to normal. Winds will be light tonight and Saturday morning, then northwest 10-20 mph Saturday afternoon, with gusts to 30 mph in south-central Idaho and south of the Snake Basin. Gusty winds also near thunderstorms. LONG TERM...Monday through Friday...Persistent low-amplitude upper trough along the coast and ridge over the interior west will keep temps warm (i.e., slightly above normal) in Idaho, but near normal in Oregon. No rain is forecast with monsoon moisture staying south of our CWA. Areas of smoke for at least another week. && .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...KA AVIATION.....SP SHORT TERM...LC LONG TERM....LC
Area Forecast Discussion
National Weather Service Denver/Boulder CO
947 PM MDT Fri Aug 9 2024 .KEY MESSAGES... - Scattered to numerous showers and thunderstorms are expected each day through the weekend. The primary threat will be flash flooding on the recent burn areas as stronger storms will produce locally heavy rainfall. - Much warmer on Sunday with lower precipitation chances. - Slightly cooler Monday with better precipitation chances. The main threat will be heavy rainfall with a couple strong to severe storms possible. - Gradual drying trend expected from Tuesday through the end of the work week with near to slightly above normal temperatures. && .UPDATE... Issued at 944 PM MDT Fri Aug 9 2024 Area radars are showing scattered light rain showers decreasing over some of the plains at this hour. There is another batch of rain showers to get into Larimer and Weld Counties from Wyoming in the next few minutes. Latest models are not showing much convection over the CWA after 06z. Will alter the pop grids with reality and the latest high resolution models and lower pops over some of the plains. Will make some grid adjustments to sky and wind grids based on current trends. && .SHORT TERM /Through Saturday/... Issued at 254 PM MDT Fri Aug 9 2024 Radar shows plenty of convection, but overall intensity has decreased as the leading edge of showers and storms is moving across more stable air on the plains. Satellite imagery has shown some recovery behind today`s early convective disturbance, with more development upstream into western Colorado and northern Utah. However, instability is marginal since some of the energy has been used up. We`ll likely see more of the same (relatively high coverage but weaker convection) through this evening, as the forecast area resides in the right entrance region of an upper level jet. CAMs have been quite poor with the earlier development of convection, but appears the 18Z HRRR and NAMNest are at least initializing a little better than earlier runs today. With lift and upward QG forcing into the late evening hours, we`d expect a few of these showers and storms to linger into the midnight hour if not into the wee morning hours Saturday. Skies should then gradually clear, although some stratus and low clouds/fog still expected over the eastern and northern plains. On Saturday, we should see less stratus and an easier breakup with more southerly low level flow. This will allow temperatures to start a warming trend, with highs warming into the 80s at least in/near the Denver metro area and points east and southeast. There are still indications some cooler boundary layer air could hold highs in the 70s closer to the Wyoming and Nebraska borders. With additional heating though, and still rich low level moisture, MLCAPE will build to 600-1400 J/kg - at least in the interface of the warmer temperatures and higher boundary layer moisture. At this time, we think that ends up closer to the I-25 Corridor than the eastern plains. Given sufficient shear, a couple strong to severe storms will be possible in that instability axis. Shower and storm coverage should be fairly high once again in/near the mountains, I-25 Corridor, Palmer Divide, and Cheyenne Ridge. && .LONG TERM /Saturday night through Friday/... Issued at 254 PM MDT Fri Aug 9 2024 Saturday night, upper level high pressure will be centered over Texas with a moderate west to northwesterly flow aloft over Colorado. This pattern should result in scattered showers and thunderstorms continuing into the evening across the forecast area. Latest models are showing most of the activity focused from South Park eastward across the Southern Foothills and Palmer Divide. With ample moisture and instability, some of the storms could be strong with hail, gusty winds and locally heavy rainfall. On Sunday, the upper ridge begins building north across the Rocky Mountain Region with continued northwesterly flow aloft over the CWA. Model soundings are suggesting some downsloping flow east of the mountains which should result in a decrease in low level moisture, lower precipitation chances and much warmer temperatures (upper 80s to lower 90s) across the Front Range Urban Corridor and adjacent plains. Further east across the plains, the cooler moist air may linger with much cooler temperatures, especially across the far northeastern corner of the state. This area may be too stable to see much convection. However, there may an zone of higher instability between the cooler stable and warmer drier air masses with the potential for a couple of strong to severe storms with hail and locally heavy rainfall across portions of the plains. Further west, the convection should be higher based with gusty winds and mostly light to moderate rainfall expected. On Monday, the upper level flow weakens and becomes more westerly as the upper ridge shifts eastward into the Central Plains States. This pattern may allow an increase in monsoonal moisture across Colorado. In addition, models are showing increasing low level moisture across the Northeastern Plains behind the passage of a weak cool front. With PW`s ranging between 0.75" in the mountains to 1.25" on the plains, some of the storms could produce heavy rainfall, especially across the far eastern counties where the moisture will be highest. In Addition, there could be enough shear and instability to produce a few severe storms across the plains as well. For the Tuesday through Friday period, moisture and precipitation chances are expected to gradually decrease with near to slightly above normal temperatures each day. && .AVIATION /06Z TAFS through 06Z Sunday/... Issued at 944 PM MDT Fri Aug 9 2024 Models keep the northerly wind in at DIA through about 09Z later tonight. After that, weak normal drainage patterns are a good bet. The low Stratus has pushed out of DIA and cross sections do not show it to get back into DIA overnight. So no ceiling issues after 06Z. && .HYDROLOGY... Issued at 254 PM MDT Fri Aug 9 2024 Overall storm intensity through the afternoon and evening should be less than the initial convection given some of the instability is already worked over. However, the airmass remains quite moist and a couple stronger storms could still produce brief heavy rain and thus a limited threat of flash flooding in the recent burn areas til about the midnight hour. Saturday will feature scattered to numerous showers and storms again in the afternoon. More instability will be present, and thus isolated to scattered stronger storms will be capable of producing heavy rain, and at least a limited threat of flash flooding for the burn areas. The most recent burn areas will be most susceptible. They will be moving along fairly quickly at 20-25 mph given the flow aloft, but stronger storms in the mountains and foothills will still be capable of producing a quick one half inch of rain in 15 minutes. Stronger storms on the plains could produce a quick 1 to 1.5 inches in 30 minutes as they intensify in a more unstable airmass. The burn area flood threat each day next week will depend on the timing of disturbances in the flow and the amount of sunshine. While the atmosphere will remain moist, storms should be moving, which should limit the threat to burn areas and reduce it there. There will eventually be a drier environment by later in the week, but this trend looks to be very slow. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......RJK SHORT TERM...Barjenbruch LONG TERM....JK AVIATION.....RJK HYDROLOGY....Barjenbruch
Area Forecast Discussion
National Weather Service Cheyenne WY
537 PM MDT Fri Aug 9 2024 .KEY MESSAGES... - Areas of dense fog possible into Saturday morning, especially over the Interstate 80 summit. - Another nocturnal shower and thunderstorm event this evening, starting west of the Laramie Range and possibly making it to Cheyenne towards midnight. - Expecting a gradual warmup through the weekend returning to near normal temps and daily chances for afternoon and evening showers and thunderstorms continuing. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 230 PM MDT Fri Aug 9 2024 Surface boundary lays along a line from a low over south central Colorado to near Craig Colorado into northern Utah. East to southeast upslope low level winds with low clouds and fog along with light drizzle in the upsloping flow east of the Laramie Range. Getting breaks in clouds west of the Laramie Range. Temperatures at Rawlins up near 80 degrees with Laramie near 70. Current SBCAPE west of the Laramie Range up near 1200 J/KG and radar showing convection starting to develop across northern Carbon and Albany Counties. HRRR and RAP simulated radar develops a line of thunderstorms in Sweetwater County towards 00Z that moves through Carbon County early this evening. Not too concerned with severe thunderstorms...but if the HRRR solution comes true...could have strong winds at Arlington and possibly Laramie. RAP SBCAPE up near 1500 J/KG over Albany County 00Z to 03Z. 0-6km shear pretty high with 40-50kts and DCAPE around 1000 J/KG. Could see a few severe thunderstorm warnings after 00Z. Main hazard will be strong downburst winds. That line makes to to the Laramie Range around 10PM this evening and moves through Cheyenne towards midnight. Definitely not looking at severe storms east of the Laramie Range and storms weaken considerably as they move into the southern Panhandle. Convection gets going again Saturday afternoon as highs climb into the low 80s. ECMWF/NAM/SREF and GFS all showing pretty good QPF Saturday afternoon across much of southeast Wyoming that eventually makes it into the Panhandle towards 00Z. Long/skinny CAPE profiles and PWATS up near and exceeding 1 inch east of the Laramie Range may produce a flash flood threat mid Saturday afternoon into the evening hours. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 230 PM MDT Fri Aug 9 2024 An active weather pattern continues to be well advertised for the extended forecast. We will see near to slightly above average temperatures for mid August as well. Monday will bring daytime highs in the 70s to mid 80s for the lower terrain, and we will be on the periphery of a departing upper level ridge. Further upstream, we will begin to see the influence of an approaching upper level longwave trough from the Pacific NW. Since we will be wedged in between these two weather features, rich monsoon moisture will trek northward. PWATs of 1.0" to 1.5+" are forecast to surge north by Monday evening. Atmospheric instability from daytime heating and steep lapse rates will be combined to produce some much-needed rainfall across our cwa. The GFS is the most aggressive with widespread showers and thunderstorms. Should this consistent trend persist over the weekend, moderate to high confidence of localized heavy rainfall would be favored east of the I-25 corridor. Additional shortwave disturbances are progged to advect east across the CONUS through mid-week, keeping daytime highs minimized, and chances for showers and thunderstorms maximized. Thursday and Friday will bring the chances of the upper level ridge amplifying from the Four Corners region of the desert SW towards our cwa. This will begin to reduce the chances for showers and thunderstorms, and allow daytime highs to begin their trend upwards to above normal thresholds. Stay tuned for the extended forecast as the active weather pattern continues to favor above normal chances of precipitation for our cwa. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 521 PM MDT Fri Aug 9 2024 Northwest flow aloft will continue, while moist low level upslope winds help produce light rain, fog and low clouds tonight for areas along and east of Interstate 25. Wyoming TAFS...For Rawlins, scattered to broken clouds from 9000 to 10000 will prevail, with thunderstorms in the vicinity until 06Z. Winds will gust to 23 knots after 15Z Saturday. For Laramie, ceilings will lower to 3500 to 5000 feet this evening, then will improve to 10000 feet after 09Z. Thunderstorms will be in the vicinity until 03Z, and from 05Z to 09Z. Winds will gust to 25 knots until 03Z. For Cheyenne, light rain and fog will occur until 15Z, reducing visibilities to 2 miles or less, along with ceilings under 1000 feet. Ceilings will improve to 3500 feet after 15Z Saturday. Nebraska TAFS...For Chadron and Alliance, ceilings will range from 1500 to 3500 feet until 06Z, with occasional light rain and fog reducing visibilities to 3 to 5 miles and ceilings from 500 to 2500 feet. After 06Z, clouds will be scattered to broken at 10000 feet. For Scottsbluff, ceilings will range from 600 to 2000 feet until 16Z Saturday, with areas of fog reducing visibilities to 3 miles until 03Z. After 16Z Saturday, clouds will be scattered at 10000 feet. For Sidney, ceilings will range from 600 to 2000 feet until 12Z, then ceilings will improve to 4000 feet. Areas of light rain and fog, reducing visibilities to 2 to 6 miles, will occur until 12Z. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...GCC LONG TERM...BW AVIATION...RUBIN
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1028 PM EDT Fri Aug 9 2024 .SYNOPSIS... A cold front will track across the region through this evening, bringing the potential for a round of scattered showers and thunderstorms. High pressure will build into the area this weekend, lingering through the middle of next week, while the front stalls over the Southeast and keeps daily shower and thunderstorm chances in place, especially over the southern zones. && .NEAR TERM /THROUGH SATURDAY/... As of 1025 PM: Scattered convection continues to slowly move south across the NW Piedmont into the Southern Piedmont this evening. Isolated convection seen over the western Upstate. The HRRR slowly moves this activity southeast with it dissipating before daybreak. Have followed these trends in the PoP with this update. The severe chances have fallen but isolated heavy rainfall remains possible in the high PW and slow moving cells. Isolated flooding could also develop. With the convection in place, there`s much more debris clouds than expected earlier which could put a damper on the radiational cooling. Still have some patchy fog in place, but the chances of dense fog have diminished. The mountain valleys would have the best chance. Lows overnight will remain a few degrees abv normal with the warm airmass remaining unchanged. Sat will see afternoon general tstms again, but the activity will be mostly limited to ern zones near the stalled frontal zone as downslope warming ensues west. Highs Sat will be similar to today with readings in the low to mid 90s across the non/mtns and u80s over the mtn valleys. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 141 PM EDT Friday: A closed upper low will slide across the Great Lakes Sunday and into Quebec by Monday. It`ll be distant enough that little if any DPVA forcing will develop over the Carolinas during the short term. However, persistent pockets of upper-level moisture will stream around the periphery of this feature and across the Carolinas; following some brief drying on Saturday night and the first part of Sunday, better moisture will build back in aloft and keep skies partly cloudy or worse. In association with one of the passing vort lobes, a weak reinforcing cold front will make its way across the CWA on Sunday, reinvigorating the stagnant boundary across the southern tier of the forecast area. So, by Sunday afternoon, the environment will be primed for destabilization along and south of I-85, with sbCAPE values surging to 1000-1500 J/kg. Subsident profiles elsewhere should keep convection at bay, limiting initiation or preventing it entirely. Even over the southernmost unstable reaches of the forecast area, what CAMs extend out that far depict little if any convective activity. Otherwise, temperatures botgh Sunday and Monday will stay a category or so below climo, only hitting the mid- to upper-80s. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 207 PM EDT Friday: The upper jet will remain displaced just to our north through the extended, allowing for alternating periods of more and less active weather as shortwaves drop out of the Midwest and into the Carolinas. The first of these will arrive Monday night, ushering drier air aloft and and at the surface as a high pressure system slides across the Upper Ohio Valley. The second will arrive sometime Wednesday or Thursday, though models begin to diverge on timing by this point in the forecast. Instability generally looks anemic on Tuesday and Wednesday, but should start to improve on Thursday. A 500mb speed max will arrive on Thursday, affecting mainly the NC zones...so if the elevated shear associated with this feature intersects the improving instability currently depicted in operational guidance, Thursday could be our next potential severe weather day. Otherwise, temperatures will remain near or up to a category below normal through the end of the week, as the ever-present upper trough continues to exert its influence over the region. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: VFR conditions continue through the evening. Isolated convection has developed and will move very close or over KHKY soon so a short TEMPO starting now. It will also be near KAVL and the SC sites so VCSH there. CAMs suggest the storms will eventually move over KCLT, so have a later TEMPO there. Winds have gone S to SW for all but KAVL where they remain NNW. Winds become light and variable overnight with convection and clouds dissipating. There may be mountain valley fog, so put some MVFR in at KAVL. Otherwise, don`t expect any restrictions. There will be some afternoon VFR cu Saturday, but looks like best chance for convection will be to our southeast. Light NE wind in the morning becomes NW to SW for the afternoon. Outlook: Expect generally isolated to scattered diurnal convection across the region each day through the middle of next week. Patchy fog and low stratus will be possible each night in the mountain valleys and in locations that receive rainfall. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...MPR NEAR TERM...RWH/SBK SHORT TERM...MPR LONG TERM...MPR AVIATION...RWH
Area Forecast Discussion
National Weather Service Gray ME
1129 PM EDT Fri Aug 9 2024 .SYNOPSIS... Debby passes west of the region tonight with a period of heavy rain possible overnight...especially in the mountains. Clearing skies arrive with warm temperatures Saturday...before seasonably dry weather arrives to end the weekend Sunday. Fair weather looks to persist through most of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1130 PM Update... Quick update to lower the Flood Watches in the north as the precip has exited the region. Also extended the rip risk along the coast through to WFO CARs area. Otherwise, have dropped the flood advisory in the North Conway area. The rest of the forecast will remain unchanged. 1025 PM Update... The precipitation continues to settle south of the mountains which is in relatively good agreement with the latest HRRR solution. This will bring the highest rainfall rates to southern areas over the next few hours. Have adjusted pops accordingly. Have introduced patchy fog for the late night hours. After a brief surge of winds, the gradient will relax leading to pooling of low level moisture. May be able to lower the Flood Watches over northern areas over the next few hours as precipitation clears the region. Prev Update... Line of showers and storms continues to progress east per latest radar imagery. The latest HRRR has this precipitation moving out of the region relatively quickly during the late night/early morning hours. However, a weak wave may ride up this boundary, temporarily stalling the precipitation over portions of southern New Hampshire and Maine. We continue to monitor for the potential for flash flooding and/or severe weather. Greatest mixing has occurred in southern New Hampshire and southwest Maine as surface dew points continue to climb through the lower to mid 70s. Fog will be persistent, especially over Maine until the occlusion crossing the region. Prev Disc... Impacts: * Heavy rainfall will pose a Flash Flood threat across the area, but especially in the mountains due to rapid runoff. * Strong to severe thunderstorms are possible this evening. The primary threat is damaging wind gusts, but an isolated tornado is not out of the question. Visible satellite and radar shows the center of post-tropical Storm Debby over central New York at this hour. It will continue its northeastward movement through tonight while pushing in a tropical airmass over our area. This combined with a trailing cold front will bring the threat of flash flooding due to excessive rainfall, and strong to severe thunderstorms. Flash Flooding: Maintained the area of the Flood Watch as northern New Hampshire is certainly the most vulnerable area tonight as showers will be further enhanced by an upslope wind component. However, anywhere in the CWA could see a flash flood purely from the expected rainfall rates. The GYX 12z sounding was already observing PWAT values just over 2 inches, with models continuing to show peak values around 2.25 overnight. This will allow storms to achieve rainfall rates in the ballpark of 2"+. With this being said hi-res guidance continues to be very progressive with this area of heavier showers, which means flash flooding in the less vulnerable southern areas may only occur with persistent or training storms. Either way expect at least tropical downpours that could be hazardous to travel, especially at night, as they would reduce visibility. The period of heaviest rains is expected overnight. For additional details on this threat, please see the hydrology section below. Severe: Breaks in the moist conditions and warm air advection are building up instability in southern and western New Hampshire today. SPC mesoanalysis is already showing surface based and mixed layer CAPE values around 500 j/kg. This is expected to increase into the evening, as well as increasing shear and helicity as Debby continues to move to the northeast. The primary threat with these storms will be wind as convection and heavy rain could mix down damaging wind gusts from a 70KT low level jet moving overhead. The increased shear and helicity means an isolated tornado is not of the question. The severe weather threat runs from now till around midnight, then it should quickly taper off. Maine has stayed mostly stable today with drizzle and patchy fog persisting, so would expect the severe threat to be limited here. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/... Impacts: * Long period wind swell will pose a rip current threat Saturday. Hi-res guidance continues to be very progressive with the band of rain Saturday morning, suggesting the bulk of it could be done by 10 AM. This means Saturday is shaping up to be warm, a bit humid, and clear. High temperatures will climb into the mid 80s south of the mountains, with slightly cooler upper 70s to the north. If folks find themselves heading to the beach, they should be aware that wind swell whipped up by the departing system will pose a high rip current risk. Clear skies will allow low temperatures to drop into the 50s Saturday night. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... The 500 MB pattern across NOAM and its environs show ridging over the E half of the continent shifting poleward and spreading east into central Canada, while weak toughing settles over NB and the maritimes and across the NE CONUS. With sfc ridging pushing in from the W. This is very weak ridging and the flow will become quite stagnant by midweek. There is not a lot of forcing so for the most part it should be dry, but any weak waves that rotate around the weaken trough to our NE will set off some the stagnant flow will cause a chance for SHRA/TSRA. Right now the best chance looks like Wed/Thu. Temps through the extended should run fairly close to normal, depending on flow direction as usual. On Sunday, weak ridging behind the exiting tropical system and the next trough diving SE through S ON will make for a mainly a dry and seasonably warm day, with highs from the mid 70s in the mtns to the low 80s in the S, and there should be enough gradient WSW flow to keep the sea breeze at bay through most of the day. Could see a few showers move into the mtns late, but the chance there will be Sunday night. The forcing associated with that 500 MB trough will weaken as it moves through, so while showers in the mtns are possible, they will generally be light where they do occur. Lows range from the mid 50s N to the low 60s S. On Monday afternoon another weak wave moves into the base of the 500 MB trough nearby, and the 12Z Euro has backed off showers some, while the GFS has not, although the Euro still has some very light QPF. The best chance will be in the N, and that is where the chc POPs are. Partly sunny covers the sky forecast and highs are mostly in the 70s to around 80 in the S. For the most part the Euro stays dry on Tue, and have leaned in that direction. Highs on Tuesday rebound a few degrees from Monday, generally in the mid 70s to low 80s. Wed looks similar to Tuesday, although there is a possibility of a few showers. Thursday, POPS increase to Chc, as a wave move around the upper level trough to our NE, which means a better chance of showers across much of the CWA, with more clouds, and highs a few degrees lower than Wednesday. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Short Term...IFR/LIFR will continue into early tomorrow morning, with a band of heavy rain and thunderstorms moving through overnight. Wind gusts 25-30 kts are possible within this band as well. Conditions will quickly improve to VFR Saturday morning as a front swings through with wind gusts tapering off as well. Long Term...Mainly VFR expected Sun-Wed. There is a good chance of valley fog Sunday night, and could see a few showers Monday aft/eve. I think there will be enough clouds around Mon night to preclude valley but may see it again Tuesday night with stagnant flow in place. && .MARINE... Short Term...SCA conditions will continue through at least Saturday night as winds southwesterly winds will be gusting upwards of 30 kts, with a few gusts to 34 kts possible, into Saturday morning. Afterwards, seas will remain elevated, 5-7 ft, through Saturday night. Long Term...Winds/seas continue to subside on Sunday and then stay stay below SCA conditions through Wed. && .HYDROLOGY... The precipitation will continue to shift to southern areas overnight. However, with heavier rain from earlier, will continue to monitor the Pemi and Saco Rivers across the mountains of central NH. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...High Risk for Rip Currents from 8 AM EDT Saturday through Saturday evening for MEZ023>028. NH...High Risk for Rip Currents from 8 AM EDT Saturday through Saturday evening for NHZ014. MARINE...Small Craft Advisory until 11 PM EDT Saturday for ANZ150-152- 154. Small Craft Advisory until 11 AM EDT Saturday for ANZ151-153. && $$ Cannon
Area Forecast Discussion
National Weather Service Marquette MI
742 PM EDT Fri Aug 9 2024 .KEY MESSAGES... - Scattered to numerous rain showers and breezy winds near 30 mph today and tonight. Strongest winds expected near western lakeshores and in the Keweenaw. - Scattered showers and breezy conditions continue Saturday before quiet and dry weather returns Sunday. - A beach hazard statement remains in effect for today`s anticipated dangerous swimming conditions for Alger County beaches. - Warm, dry weather expected early next week thru at least the midweek period. && .SHORT TERM /THROUGH TONIGHT/... Issued at 232 PM EDT Fri Aug 9 2024 GOES-16 Day Cloud Phase imagery shows a scattered to broken field of banded low cu with some mixed phase clouds over the central UP. RAP analysis shows a stacked closed low slowly approaching James Bay with a 1007mb surface pressure. At 500mb, the closed low has a lobe that is rotating around the parent low with the axis currently over the Minnesota arrowhead. This will rotate over the UP today, and the PVA from that lobe will support the already ongoing lake effect rain showers that are apparent on satellite and radar imagery. HREF mean 850mb temperatures throughout today and tonight will be around 4 C over Lake Superior. With lake temperatures still between 13 and 21 C, there`s plenty of lake-induced instability to generate rain showers into Saturday morning and with the slow movement of the stacked low to the northeast, the low levels will remain cyclonic enough to support shower development. Mean accumulated precip from 8AM this morning to 8AM Saturday morning only peaks at around 0.6 inches in the west, so impacts should be minimal from the rainfall. Of more impact will be the winds, with the HREF showing widespread wind gust potential up to 30 mph especially along the Lake Superior shorelines. Temperatures today under cloudy skies and showers will only peak in the 60s, with lows falling to the 40s. && .LONG TERM /SATURDAY THROUGH FRIDAY/... Issued at 341 PM EDT Fri Aug 9 2024 With the midlevel low and associated cool airmass situated over the area through the weekend, and additional shortwave energy rotating around it, expect showery weather to continue Saturday through Saturday night. In addition, with 850mb temps falling to around 5C per multi ensemble mean and with Lake Superior sfc water temps ranging generally from 17 to 21C, there will be some lake enhancement to the showers. As a moderating airmass moves in Saturday night while the main low moves out, showers slowly taper off across the western UP but linger to the east overnight. Highs Saturday will be in the upper 50s to upper 60s F, then expect lows ranging in the mid 40s to mid 50s (coolest interior-west). NW winds remain breezy through Saturday, gusting to 20-30mph. Dangerous swimming conditions are expected for the Lake Superior beaches of Marquette and Alger counties on Saturday due to the wave action from 20-30kt winds over Lake Superior. With departure of the last shortwave and with the mid-level low exiting farther to the east, showers across the eastern UP into early Sunday wrap up by the afternoon. Under a mix of clouds and sun, temps will rise into the upper 60s to mid 70s F. Tranquil weather is expected into next week as strong positive height anomalies across central Canada induce ridging over the Great Lakes. Diurnal instability will be on the limited side, so potential of any afternoon convection is very low. If any diurnal convection does happen to develop, it would be isolated in coverage at most. The better chance for any shower activity (only 20-30% chance) would be in the late Wed/Thu time frame with loose model agreement for a weak shortwave ejecting out of the Plains to reach Upper MI at that time. However, with ridging nearby, this feature may be suppressed too far to our south for any impacts over the UP. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 742 PM EDT Fri Aug 9 2024 Borderline VFR/MVFR conditions will deteriorate to MFVR overnight as the parent lower pressure over northern Ontario dips southeast over Lake Superior tonight, lowering cigs and spreading more scattered to numerous light rain showers across Upper Michigan, particularly at IWD and CMX. Conditions improve back to VFR tomorrow morning, but scattered lake-effect showers and clouds could keep cigs borderline MVFR once again. Gusty northwest winds upwards of 25 mph continue overnight through tomorrow, especially at IWD and CMX where gusts could push upwards of 30-35 in the afternoon. && .MARINE... Issued at 341 PM EDT Fri Aug 9 2024 An early fall-like low pressure system will affect Lake Superior into the weekend. Cooler air moving across the still warming waters of Lake Superior (sfc water temps now generally 63-70F) will lead to increasing instability and deeper mixing, allowing for stronger winds to reach the lake sfc. W to NW winds of 20-30kts have become common, and should continue through Saturday. Some gale force gusts are possible today over western Lake Superior with probability at 10- 30pct, greatest toward the nearshore waters of Upper MI. Tonight thru early Sat aftn, potential of gale gusts will shift to areas from n of the Keweenaw down to btwn Marquette and Grand Marais. Probability of gale gusts in that area is 10-40pct, greatest from around Stannard Rock to Marquette and Grand Marais where water is warmest. Winds then diminish Sat night to 10-20kt w half and to 15- 25kt e half. On Sun, expect W to NW winds gusting to around 20kt. High pres building over the Great Lakes region will then lead to winds mostly under 15kt Mon-Wed. In addition to period of stronger winds into the weekend, waterspouts are possible across Lake Superior. The potential of waterspouts will diminish from w to e on Sat. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ006. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...GS LONG TERM...LC AVIATION...BW MARINE...LC
Similar to previous forecast discussions, the ridge continues to
weaken, making way for deeper marine layer, breezy onshore
conditions during the afternoon and evenings, and slightly cooler temperatures as the trough continues to build. With the deepening of the marine layer, expect a rinse and repeat for low clouds tonight into Saturday morning along the coast and extending further inland and into the valleys. Temperatures tonight will be relatively the same as last night with temperatures in the 50s to low 60s over most of the region, with higher terrains and isolated spots seeing 70s. The gradual, slight cooling will be reflected for Saturday maximum temperatures, with a 1-3 degree difference than today. Highs will be in the 80s to 90s inland, with some 100s in the mountain ranges. The coastal areas will repeat its` usual and seasonal temperatures of high 50s to 60s. && .LONG TERM... (Saturday night through next Thursday) Issued at 1108 AM PDT Fri Aug 9 2024 Ensembles and clusters analysis continues to show agreement that the upper level trough will continue the cool down in temperatures starting Sunday with temperatures dropping to mostly 70s and 80s inland and some isolated spots in the 90s. Coastal areas will remain consistent of 50s to 60s. Going into early next week, the temperatures continue to drop a few degrees each day. Chances for above normal seasonal temperatures are looking less likely as Climate Prediction Center 6-10 day outlook continues to suggest near normal to below seasonal temperatures. && .AVIATION... (00Z TAFS) Issued at 545 PM PDT Fri Aug 9 2024 Satellite and observations show coastal stratus and fog /LIFR-IFR/ otherwise it`s VFR. Lower level dry air on gusty northwest winds has recently mixed into the boundary layer dissipating stratus coverage over the coastal waters, but now more recently seeing a return of saturated air (clouds) vs unsaturated air (cloud free). During the early evening timeframe dry air above the marine layer may still mix into the boundary layer along the immediate coastline, otherwise nocturnal cooling will take over resulting in increasing areal coverage of stratus and fog. The marine layer depth is 1200 feet per recent Bodega Bay and Fort Ord profiler data. The onshore SFO-SAC 4.4 mb pressure gradient currently predominates while the ACV-SFO gradient is 3.2 mb. Onshore winds will usher stratus and fog at least locally inland tonight and Saturday morning. Conditions improving to MVFR-VFR near the coast by late morning Saturday. Vicinity of SFO...Low to moderate confidence VFR holds through the evening, if the marine layer depth holds unchanged this may help keep VFR going a while longer. Stratus was mixing out, but now is rapidly filling back in again just upstream from SFO Airport per recent satellite imagery. RAP model is showing IFR by mid evening. For now, the 00z TAF shows IFR 11z-15z Saturday, will closely monitor observations and amend as needed. Onshore wind continuing with periodic gusts to around 25 knots in the afternoon and evening. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Stratus, fog, patchy light drizzle /LIFR-IFR/ moving inland this evening and overnight while an eddy circulation is forecast to develop over the northern Monterey Bay during the evening. Stratus, fog and patchy light drizzle improving to MVFR- VFR by late Saturday morning. Mainly onshore winds 5 to 15 knots. && .MARINE... (Tonight through next Thursday) Issued at 511 PM PDT Fri Aug 9 2024 Gusty northwest winds will continue over the coastal waters through the middle of next week. This will cause rough seas over the outer waters, including rough seas to expand across the inner waters at the end of the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 3 PM PDT Sunday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory from 9 AM Saturday to 3 AM PDT Sunday for Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm. && $$ SHORT TERM...SO LONG TERM....SO AVIATION...Canepa MARINE...Murdock Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Reno NV
127 PM PDT Fri Aug 9 2024 .SYNOPSIS... * Smoke and haze will continue to impact portions of northeast California and northwest Nevada through the weekend. * Outside of a 10-15% chance for storms in Southern Mono/Mineral Co this afternoon, the forecast largely remains dry. * Breezy winds Friday-Monday will bring enhanced fire weather concerns along with choppy lakes. This will usher in cooler temps for next week. && .DISCUSSION... * Smoke and haze from the Park and Crozier wildfires will continue to impact portions of northeast CA and northwest Nevada, but exact impacts will depend on fire activity. The current wind pattern remains largely the same through the weekend, so anticipate similar impacts unless the fires are to burn more actively. HRRR model simulations show a similar footprint, although slight fluctuations north/south could bring impacts to parts of Reno, especially the south end of the Truckee Meadows, in addition to the Tahoe Basin. You can find information on current air quality at fire.airnow.gov. * A series of troughs brushing just north of the region will bring increased afternoon breezes through Monday, with the greatest risk (50-80% chance, location dependent) of gusts exceeding 30 mph on Sunday and Monday. The strongest winds aloft come in Sunday night with an upper trough passage, so anticipate the midslopes and ridges will remain rather breezy through the night. The fact that the peak upper level winds do not align with peak mixing on Monday will be the saving grace from seeing a longer duration critical fire weather event. Still, there are enhanced concerns and a 1-4 hour window of critical conditions is possible in localized areas. Areas of greatest concern will be along the Sierra Front and portions of northern Nevada. Area lakes will also be choppy. If the trough slows further and the two align, winds have the potential to be stronger on Monday. * These troughs will also usher in a cooler airmass, which will be a welcome change after the hot summer the region has experienced so far. By Monday and through next week, temps will be near to below normal for this time of the year. The cooler airmass also means we`ll start to see some improvements to RH recovery overnight as lows dip into the 50s to near 60 for warmer valleys and into the 30s and 40s for colder Sierra valleys. Longer range pattern in the ensemble cluster analysis is in good agreement we`ll maintain a troughy pattern, meaning near to below normal temps and breezy afternoons. -Dawn && .AVIATION... * For KRNO: Latest smoke models keep the smoke impacts just south of the region, more Washoe Valley into north Carson. Light haze isn`t out of the question, but visibility shouldn`t be impacted. Only other concern will be breezy WSW afternoon winds each day from approximately 21z-03z with gusts of 20-25 kts. Similar winds can be expected across the region, with winds remaining elevated Sunday night as a trough swings through the region. * Smoke from the Park and Crozier Fires may bring narrow bands of MVFR conditions late day into the morning hours to KCXP/KMEV/KSVE, but primarily that would impact slantwise visibility. Exact impacts and extent of smoke will be dependent on fire activity. * A 10% chance for showers and isolated thunderstorms this afternoon for the Eastern Sierra of Mono Co (including KMMH) eastward towards KHTH. Storms may produce reduced cigs/vis, but it will be localized, along with gusty and erratic outflow winds. -Dawn && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
859 PM PDT Fri Aug 9 2024 .SYNOPSIS...Chances for afternoon and evening showers and thunderstorms will continue each day through the weekend for areas near and east of a line from Yucca Valley to Mount Charleston to Rachel as monsoonal moisture remains in place. Above normal temperatures will continue as high pressure persists over the southwestern states. Drier air is forecast to push into the region next week, reducing thunderstorm chances and bringing slightly cooler temperatures to the region. && .UPDATE...Convection was dissipating early this evening altough an isolated thunderstorm recently developed in far northeast Moahve County near Colorado City. The latest high res models support mostly tranquil weather across the region tonight. Saturday afternoon should be more active over Clark County. The 00Z HRRR indicates that thunderstorms that develop over the Spring Mountains will move slowly toward the southeast which would take them over the Las Vegas Valley. A moist and moderately unstable air mass will remain in place as shown in this afternoon`s sounding...Pwat values near 1.4 inches and surface CAPE values around 1400 J/kg. The forecast was updated with the 01Z NBM and a slight blend from CAM PoPs which increased PoP values to 20-30 percent across the Las Vegas Valley Saturday afternoon. && .PREV DISCUSSION... 138 PM PDT Fri Aug 9 2024 .SHORT TERM...through Sunday night. Early afternoon satellite loop showed thunderstorms initiating over the Spring Mountains and towering cumulus over the Sierra Nevada, the Nevada National Security Site, and the higher terrain of northern Mohave County. Debris clouds from the overnight and early morning MCV-driven rain had evaporated, and lifted indices had dropped to -4 in Clark and San Bernardino counties. Convective inhibition was also decreasing. Thus, expect isolated to scattered storms again this afternoon and evening along and southeast of I-15. A second area of concern is Lincoln County. Thunderstorms had already initiated just north of our CWA, and high res models show them propagating farther south as the afternoon wears on, which is supported by ongoing satellite trends. The NBM captured this idea, and suggests activity will persist well after sunset. Saturday and Sunday, Mohave County should see the highest thunderstorm chances under east to southeast flow around an easterly wave meandering around the Baja, with more widely separated storms developing over the higher terrain in Clark and San Bernardino counties. Overall, expect temperatures not to change much, perhaps going up a degree or two from today to Saturday and falling a degree or two from Saturday to Sunday, but point temperatures could vary a lot depending on exact location and timing of thunderstorms. .LONG TERM...Monday through Thursday. The upper level trough will continue to push into the West Coast next week. This will scour out the moisture and bring an end to the scattered showers and thunderstorm activity. Anomalously high PWATs will be will be confined to eastern Lincoln and Mohave counties Monday afternoon, then by Tuesday afternoon normal to below normal PWATs will be in place for most areas. This dry air will remain over the region through the rest of the forecast as the probability for PWATs over 1 inch drops to 30% or less in the GEFS by Wednesday morning. The chance for afternoon showers and thunderstorms will decrease and shift east each afternoon next week, with a potentially dry forecast for all areas by Wednesday or Thursday. With the trough sitting nearby and decent southwesterly flow aloft, breezy afternoon winds can be expected. The risk for impactful winds over 40 MPH is low to none (20% or less probability), so most likely it would be typical afternoon breezes of 25 to 35 MPH, especially Monday. However. Will need to watch where the better winds will set up and how fuels have changed with the recent rains and drier air could increase fire danger. Temperatures will remain right around normal through next week. && .AVIATION...For Harry Reid...East to southeast winds are expected for the remainder of the afternoon with speeds generally less than 10 knots. There is some potential of seeing a gust to around 12 knots this afternoon, but gusts overall should remain short-lived. Thunderstorm chances are around 30-35% over the higher terrain and only around 15-20% in the valley. There is also a slight possibility of outflow winds originating off the Spring Mountains could impact the airport after 23z with gusts up to 30 mph, but confidence does remain low. FEW-SCT clouds at or above 12kft. For the rest of southern Nevada, northwest Arizona and southeast California...East-southeast breezes are expected over most areas through this afternoon, while southerly winds take hold in the Colorado River Valley. Speeds in both locations will largely remain less than 10 knots. At KBIH and KDAG, expecting typical diurnal wind patterns. Significant thunderstorm impacts appear unlikely (15% chance or less) at the area TAF sites today though there is potential for outflow winds gusting to 20 knots. Instead, VFR conditions prevail as FEW-SCT clouds at or above 12kft persist. Thunderstorm chances will increase Saturday for the Las Vegas valley TAF sites along with EED and IFP. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Adair SHORT TERM...Morgan LONG TERM...Nickerson AVIATION...Gorelow For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter