Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/22/21

Area Forecast Discussion
National Weather Service Boston/Norton MA
1012 PM EDT Tue Sep 21 2021 .SYNOPSIS... High pressure centered south of the Canadian Maritimes moves slightly farther offshore Wednesday, resulting in increasing humidity and a risk for showers. A slow-moving front approaching from the west will be accompanied bring showers into western sections Thursday and spread across the region Thursday night and Friday. Improving conditions expected Saturday, one or two more periods of showers are possible Sunday. No big warm ups or cool downs are expected. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... More minor tweaks to rainfall chances based on observed trends. Latest runs for the HRRR and RAP seem to be verifying reasonably well, as both captured the light showers across the Cape and islands this evening. Since these were the only guidance sources to do so, leaned heavily on their solutions to update the timing and location of precipitation overnight. Temperatures were also brought back line with observed trends and updated expectations from near term guidance. 7 PM Update... High pressure centered south of Nova Scotia. Local winds show a southeast surface flow while winds at 2000 feet or higher, per the KBOX VWP, are out of due south. Increasing low level moisture. Radar shows light showers popping near the Vineyard and moving toward Cape Cod. Another batch of showers near Montauk Pt and along the RI Coast. All showers moving north. Of the CAMS, the NAM Nest is the only one to fully capture these showers. But it and the other CAMS generate a new area of showers moving toward Wrn Long Island near midnight that spreads across Srn New England overnight. So expect some light rain/showers during the night. POPs at each core should range from 25-30 pct, within a broader area of 20 pct. The forecast expands the coverage of the rain but otherwise follows the general theme of the previous forecast. Previous Discussion... The surface high pressure and mid level ridge move a bit farther offshore, with a deepening mid level trough to our west. Across southern New England, S/SE flow will bring increasing low level moisture. This allows for an increase in clouds, and the chance for patchy light rain and/or drizzle mainly over the interior. Higher surface dew points will prompt a more mild night, with overnight lows in the upper 50s to mid 60s, with areas of fog developing. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Wednesday...Surface high and mid level ridge remain centered offshore, while deepening mid level trough and associated surface low move slowly eastward through the eastern Great Lakes Region/Ohio River Valley. S/SE flow persists and pressure gradient tightens somewhat. Saturated layer once again remains below 700 mb. Expecting partly to mostly cloudy skies, with a continued chance of light rain or drizzle mainly over the interior. Above normal temperatures, with highs in the low to mid 70s. Wednesday night... Models show mid level trough becoming cut off/blocked and halting eastward progression, with surface low retrograding somewhat. Low level moisture remains in place, with a continued S/SE flow. Thus expecting another night of considerable cloudiness, with patchy light rain and drizzle mainly over the interior. Surface dew points in the mid and upper 60s, very muggy for mid-September, with overnight lows also falling into this range. Areas of fog will likely redevelop. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Big Picture... Closed and vertical low pressure over the Great Lakes lifts north into Canada. A second upper low then drops southeast from the Canadian Prairies across the Great Lakes and Northeast by the weekend, with the axis crossing New England Sunday. High pressure builds across the Northeast Monday and Tuesday. Contour heights, reflecting the deep layer, are above normal Thursday and Friday, then in the normal range Saturday through Tuesday. This may briefly dip below normal Sunday night as the trough axis moves through...but then recover to normal Monday as the trough moves off through Eastern Canada. Mass fields are similar through Friday, then show the same trend but different positioning over the weekend. Greater differences in the fields Monday and Tuesday. Overall confidence is high Thursday/Friday trending to low-moderate early next week. Details... Thursday-Friday High pressure centered over the West Atlantic, while low pressure moves slowly north through Michigan and Srn Ontario. This pressure pattern maintains a southeast flow over Srn New England, bringing low level moisture and marine temperatures. Cross sections show plenty of convergence below 925-mb and just as much divergence between 925-mb and 700-mb. Moisture cross sections show plenty of moisture below 800-mb and pronounced dry air above 700-mb. Low-end CAPE stretches north over the region, with a limited 200-600 Joules/Kg available over the region. Given the shallowness of the moisture, and the dry air aloft, this seems more like a warm frontal pattern with rain/drizzle rather than showers. Mid-level moisture is forecast to move into Wrn New England Thursday afternoon as does the right entrance region of the supporting upper jet. This may be enough to mention chance pops for afternoon showers/thunder in the CT Valley/East Slope regions. The upper support shifts east Thursday night and Friday, allowing the surface cold front to enter Western MA/CT Friday morning. The front crosses to the Central Hills by early afternoon and the East Coast Friday evening. The cold front should provide good low level convergence, with adequate mid level moisture with the front. PW values increase Thursday and peak near 1.75 inches along/ahead of the front Friday, high enough above normal to support local downpours. CAPE builds to 1000-1500 J/Kg Friday, especially in RI and Central/Eastern MA. Convective parameters are favorable for thunder. Will forecast chance pops for showers/thunder. Mixing temperatures Thursday around 10-11C support max temps mid to upper 70s. Similar temps aloft Friday but more rain suggest max temps more broadly in the 70s. Saturday-Sunday... Cold front moves offshore Friday night but lingers over the nearby offshore waters through the weekend. Passage of the second trough on Sunday may generate a wave along the stalled front. Also, the upper trough and its cold pool aloft may generate enough instability for showers on Sunday. Will forecast chance pops for showers over the southeast waters over northern/eastern areas Saturday and northern areas Sunday. Will also forecast chance pops for showers over Nrn MA Saturday night and Sunday. Monday-Tuesday... Upper low moves off to the northeast, with showers diminishing Sunday night. All models generate a wave passing south of New England Monday. ECMWF then conjures up another system coming through the Great Lakes Tuesday, while the GFS shows high pressure. With low confidence in this part of the forecast, will keep the forecast dry at this stage with mostly clear skies but with limited confidence as noted above. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...Scattered to widely scattered light rain/showers moves north from the South Coast. Greatest coverage should be over CT and western MA around and after midnight. Conditions lowering to MVFR/IFR across most terminals overnight into Wednesday morning, from low clouds and areas of fog. Localized VSBYs as low as 1/2 mile. Wednesday...IFR/MVFR CIGs improving to VFR, except for far interior terminals, where CIGs only improve to MVFR. Patchy fog lingers until 12-14Z. Patchy -RA mainly over the interior. SE wind 5-10 kts with gusts to 20 kts possible south coast/Cape/Islands. Wednesday Night...Conditions once again lower to MVFR/IFR across most terminals, with low clouds and areas of fog. Slight chance -RA. KBOS Terminal...High confidence in trends. Moderate confidence in timing. KBDL Terminal...High confidence in trends. Moderate confidence in timing. Outlook /Thursday through Sunday/... Thursday: Mainly MVFR, with areas VFR possible. Breezy. Slight chance SHRA, isolated TSRA. Thursday Night: Mainly MVFR, with local IFR possible. Breezy. Chance SHRA, slight chance TSRA. Friday: Mainly MVFR, with areas VFR possible. SHRA likely, chance TSRA. Friday Night: Mainly VFR, with areas MVFR possible. Chance SHRA. Saturday: Mainly VFR, with local MVFR possible. Saturday Night through Sunday: Mainly VFR, with areas MVFR possible. Slight chance SHRA. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight through Wednesday Night...High Confidence Tonight and Wednesday...High pressure centered offshore maintains a south-southeast surface wind 10 to 15 kts. A few gusts to 20 kts possible. Patches of light rain/drizzle with patchy fog possible. Wednesday Night....Seas building to 4 to 5 feet on the southern outer coastal waters, thus SCA headlines may be needed there. Otherwise SE winds 10 to 15 kts continue. Patchy fog possible with visibility as low as 1-2 miles. Outlook /Thursday through Sunday/... Thursday: Winds less than 25 kt. Local rough seas. Slight chance of rain showers, isolated thunderstorms. Thursday Night through Friday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers, slight chance of thunderstorms. Friday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. && .CLIMATE... The latest first sub-70 degree high temperature heading into astronomical Autumn for BOS was September 20, 1947. Still waiting on the first sub-70 max temperature after Summer. The latest first sub-70 degree high heading into astronomical fall for PVD is September 26, 2015. Both BDL and ORH have already recorded sub-70 degree highs earlier this month. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...WTB/NMB NEAR TERM...WTB/Belk/NMB SHORT TERM...NMB LONG TERM...WTB AVIATION...WTB/Belk/NMB MARINE...WTB/NMB CLIMATE...
Area Forecast Discussion
National Weather Service Grand Forks ND
1002 PM CDT Tue Sep 21 2021 .UPDATE... Issued at 1002 PM CDT Tue Sep 21 2021 A few very light showers are still lingering in far northwest MN, otherwise most activity has ended with loss of diurnal heating. Weakly positive vorticity aloft may still support these sprinkles/very light showers a few more hours before finally falling apart. There may also be additional pockets of mid and high level clouds through the night, though overall trend is towards clearing skies. Winds should begin to shift to the south-southwest on the back side of the surface high 5-10 mph, but until then we should see good rational conditions and many locations are already falling in the the 40s. It doesn`t appear likely for frost impacts outside of isolated (traditionally colder/sheltered) locations in northwest/north central MN. UPDATE Issued at 635 PM CDT Tue Sep 21 2021 Isolated showers continue to track over northeast ND and latest RAP shows this activity moving into northwest MN before dissipating after sunset (may linger a bit longer). There is sporadic lightning activity, but the intensity/frequency has diminished. Where this activity has tracked surface obs have reported anywhere from 0.03" to a little over 0.1" A quick downpour and brief lightning through sunset will be possible where this isolated activity tracks before low level decoupling/stabilization gets underway. I made some adjustments to match lingering trends in short range guidance/radar. && .SHORT TERM...(This evening through Wednesday night) Issued at 158 PM CDT Tue Sep 21 2021 Current visible metsat imagery showing cu development across northeastern zones as well as on the west side of the valley from Grafton down to the state line. Enhanced cu development associated with weak 250 J/Kg MUCAPEs in vicinity of H500 cold pool is over SE Sask/SW Manitoba and will translate eastward along the international border, with a few light showers possible as it moves into northeastern ND and northwestern MN. At most would expect a light dampening of surfaces, in otherwords very low impacts anticipated. Loss of solar will quickly dissipate L1 cu currently across the central and southern valley, while the deeper L2 cu associated with any possible SHRA may persist to mid- evening. Eventually, clearing overnight anticipated and lightening winds will allow temperatures to fall to near 40, or even the upper 30s in low spots where some very light frost is possible. Warmer temperatures west of the valley where weak mixing may continue throughout the night. Warmer and breezier on Wednesday with highs in the 70s likely and overnight lows back into the mid to upper 40s. .LONG TERM...(Thursday through Tuesday) Issued at 158 PM CDT Tue Sep 21 2021 The extended period continues to look fairly quiet, with minimal impacts expected. From Thursday to Saturday, the 500mb ridge axis shifts east of the FA, and is replaced by the next wave. There are still lots of differences in the strength, timing, and location of this next wave, which show up on the Day 3 WPC cluster analysis of 500mb heights. Overall, the timing and location associated with any precipitation still brings the lowest confidence. Some solutions are highlighting the chance for rain both Friday and Saturday, and some just Friday. However, confidence is greater that amounts should remain on the lower side, with the NBM showing rather low probabilities (ie 30 to 50 percent) for amounts greater than a tenth of an inch. The ECMWF and GEFS means favor a tenth or two mainly east of a Devils Lake to Fargo to Fergus Falls line. In the wake of this system, 500mb ridging takes back hold, resulting in warm and dry conditions for Sunday through Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 635 PM CDT Tue Sep 21 2021 Early in the TAF period isolated showers with occasional lightning activity will move from northeast ND into northwest MN through sunset, dissipating by mid evening. Brief downpours and variable gusty winds (localized gusts around 25kt) are possible though confidence in thunderstorm activity is low at terminals. Radar shows this likely to track over KGFK and possibly towards KTVF early in the TAF period. VFR conditions should prevail through the TAF period, with clearing of CU through the night. Surface high should result in a period of light and variable winds, before low pressure builds in the west and winds shift to the south. During the afternoon period Wednesday sustained winds should range from 12-15 kt and gusts around 20kt will be possible. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...DJR SHORT TERM...Speicher LONG TERM...Godon AVIATION...DJR
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1033 PM EDT Tue Sep 21 2021 .SYNOPSIS... A moist wedge of high pressure will result in cloudy and rainy conditions across the region through tonight. A strong cold front will cross the area from the northwest on Wednesday, bringing the potential for strong storms. High pressure will build in behind the front and bring cooler and drier air for the rest of the week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1030 PM EDT Tuesday: Shower coverage has remained basically unchanged this evening with better coverage east of the I-77 corridor. Isolated showers and patchy rain and drizzle continue elsewhere. This pattern should linger into the overnight as forcing will be weak overnight. Very little in the way of instability overnight keeps the thunder threat to a minimum. Can`t rule out a rumble of thunder, but overall chance is very low. Deep moisture and forcing return late tonight into Wednesday as an upper low rotates through the OH River Valley pushing a cold front into the area. All of the guidance shows the wedge over the area dissipating with southerly flow developing. The guidance also shows CAPE values of 1000 J/kg or so developing over the I-85 and I-77 corridors. Despite the strong forcing, shear looks to be the limiting factor with only moderate shear at best and even weaker effective shear. Helicity values also look to be on the low side without a strong low level jet and no significant wedge boundary forecast. Still expect numerous to widespread showers to develop along and ahead of the front with scattered thunderstorms. With the potential for moderate instability and some shear, isolated strong to severe storms are possible. Isolated flooding may also develop if convective rain rates can increase even with the lack of low level jet. Low end gusty winds may develop ahead and behind the front. Drying does take place behind the front with precip chances ending for many locations by late afternoon. Lows tonight will be up to 10 degrees above normal. Highs Wed will be near normal outside of the mountains and a little below normal across the mountains. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of noon Tue: Some question as to whether front and/or convective line will have cleared the area by 00z Thu, the beginning of the short term period. Recent NAM runs have trended more "cut off" with the upper low to our northwest, which lends itself to a slightly slower fropa. The 12z HRRR and NAMNest depict convection still in the I-77 counties in the 00-03z timeframe, so it looks wise to maintain some PoP in that area thru the evening. Amplifying 925-850mb winds associated with LLJ look to bring PWATs close to 2 inches around 00z, and also should lead to strengthening 0-1km/0-3km shear. Although 0-1km shear is a better predictor of damaging QLCS threat, fwiw, hodographs start to exhibit excellent curvature on NAM and NAMNest soundings from Greensboro around 00z, moreso than at Charlotte. HREF shows an uptick in the coverage of updraft helicity streaks as the convection is exiting our area, reflecting the improving environment. So, a narrow window exists for severe and flooding threat to worsen around or just after sunset along our eastern border, but the remaining threats will quickly ramp down after the line exits. High pressure will build into the area and make the remainder of the short term quiet, dry, and cool, appropriate for the first weekend of fall. CAA in ensuing northwest flow across the mountains should result in gusty winds in high elevations overnight into Thursday morning, although the mixed layer will be shallow beneath a strong inversion, and advisory-level gusts look unlikely. Min temps will drop a few degrees below normal in most locations Thursday morning, trending still cooler in the calmer, better radiative conditions Friday morning. Mins likely will fall into the upper 30s in the highest elevations Friday morning, but it looks dry enough that frost seems questionable. Maxes will generally be in the 70s, with 60s expected on ridgetops. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 100 PM Tue: Dry high pressure will persist over the Southeast through the weekend and into early next week. Another closed upper low looks to rotate toward the area late Saturday, bringing a reinforcing cold front across the Appalachians early Sunday. The fropa is dry on the current slate of deterministic model runs and almost all the NAEFS members, so PoPs will remain below the mentionable threshold. While the period will start off with crisp fall conditions, modification of the airmass and rising heights in its wake suggest a warming trend, with max temps a shade above normal to begin the work week. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... At KCLT and Elsewhere: Generally IFR cigs will continue this evening with LIFR possible. MVFR vsby expected in showers. That said, an outflow boundary moving toward KCLT may cause a brief lift in restrictions and SE wind, but more in the way of showers. LIFR to possibly VLIFR cigs expected overnight with MVFR to IFR vsby. NE wind becomes light and variable overnight. SHRA coverage increases during the day Wed ahead of a front along with a chance of TSRA. Expect improving vsby but cigs remain MVFR to IFR. Winds become S to SW with low end gusts possible. Cigs only slowly improve behind the front late in the afternoon. Winds will eventually turn NW with low end gust chance continuing. Outlook: Dry VFR conditions move in behind the front Wednesday night. Gusty winds will taper off. VFR conditions persist into the weekend. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...JPT/RWH SHORT TERM...Wimberley LONG TERM...Wimberley AVIATION...RWH
Area Forecast Discussion
National Weather Service Marquette MI
744 PM EDT Tue Sep 21 2021 .SHORT TERM...(This evening through Wednesday) Issued at 253 PM EDT TUE SEP 21 2021 Latest RAP analysis and water vapor imagery show one shortwave moving slowly w-e across the Upper Great Lakes this afternoon. As this shortwave pushes e of the area late afternoon/early evening expect any remaining isolated afternoon showers to end. Another shortwave farther upstream over southern Manitoba/nw Ontario is expected to move across the Upper Great Lakes late tonight/early Wed and bring another chance for some lake-induced showers into the north central U.P. Tonight and Wednesday, models suggest 850mb temps will fall slightly, closer to 0-2C and considering Lake Superior water temps are near 15-16C, these temperatures will be near the pure lake- effect threshold for lake showers as model soundings indicate saturation through roughly 5kft. As a sfc high pressure ridge builds in from the west tonight, winds will turn northerly across the area and become slightly convergent into the north central U.P. late tonight. The combination of the lake induced instability, convergent northerly winds and perhaps some weak forcing from the nw Ontario shortwave moving across the area could spawn some light isolated showers into eastern Baraga, Marquette and western Alger counties. These showers could continue into Wed morning, but then ridging building in behind the weak shortwave trough should put an end to any showers by afternoon with a trend toward clearing skies. Under clear to partly cloudy skies, expect min temps ranging from the upper 30s interior west to mostly the lower to mid 40s elsewhere. Highs Wednesday under a mix of sun and clouds will range from the mid to upper 50s north to around 60s along the WI border and south central. .LONG TERM...(Wednesday night through Tuesday) Issued at 236 PM EDT TUE SEP 21 2021 Long term period continues to present a few opportunities for rain showers. While there still exists some uncertainty in the Thursday/Thursday night low lifting north out of the Ohio Valley, guidance is starting to paint a much clearer picture than earlier runs. High temps through the period look to be mostly in the 60s, with Thursday being the coolest with highs close to 60. Overnight lows look to range from the 40s near the lakeshores, to 40s and some 30s in the interior spots. Ridging extending out of the northern Plains is progged to extend into western Upper Michigan Wednesday night. This should help support mostly clear skies early on in the west, which will translate into a decent amount of radiational cooling. Models have been consistent with this thinking and bring lows down into the 30s in the interior west half and 40s by the lakeshores. Areas of frost are looking probable in the interior west given the light winds. More cloud cover is expected in the east thanks to a system lifting northward out of the Ohio Valley toward Lake Huron. There, lows should bottom out in the low 40s to near 40F. The aforementioned system lifting out of the Ohio Valley is progged to take on a negative tilt, then close off aloft as it lifts northward. The surface low is expected to move through or near Lake Huron Thursday and then into Ontario Thursday night. The exact position and track of the low varies among the guidance, but the western edge of the low`s deformation zone is expected to bring rain showers to the east through the day and gradually end through the night. How far west this will extend is where the uncertainty lies. As the low lifts out, brief ridging will shift eastward through Friday night before the next upper level low dips southeast into the region late Friday. Previous model runs either had this system remaining an open wave, then quickly lifting out, or a close low parking on top of the Upper Great Lakes for the weekend. Well, now model runs now have honed on a solution with a mix of the two solutions. Current thinking is for an upper level low dropping southeast through the region and exiting by the later half of the weekend. This suggests rain showers will progress west to east along the low`s cold front late Friday into Friday night with periods of showers afterwards as a secondary front/trough and some lake effect rain showers follow on Saturday. As the system lifts out on Sunday, rain showers should gradually end west to east. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 743 PM EDT TUE SEP 21 2021 VFR conditions should prevail at IWD/CMX/SAW thru this fcst period. Later tonight, light northerly winds off Lake Superior may bring bkn lower clouds near the high end of MVFR back to SAW. Could be a few -shra as well. For now, kept cigs just above MVFR threshold. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 253 PM EDT TUE SEP 21 2021 With the exception of a few localized gusts near gale, northwest winds have subsided blo gales over the east half of Lake Superior. East half winds will then subside into the 15 to 25 knots range through much of tonight. Winds will remain less than 20 kts over the west half of the lake through tonight. A low developing over the Ohio Valley on Wednesday is expected to lift north-northwest towards Lake Huron by Thursday. Depending on the track and strength of this low, there could end up being some gale force gusts on the far eastern lake Thursday. However, confidence is still low at this point, so have decided to just mention that here rather than explicitly include it in the forecast. Light winds over the west half of the lake will persist through Thursday. A trough moving across the region will cause westerly winds to increase to around 20 knots Friday into Saturday. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 8 PM EDT this evening for MIZ005- 006-014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...JP AVIATION...Rolfson MARINE...Voss
Area Forecast Discussion
National Weather Service Nashville TN
841 PM CDT Tue Sep 21 2021 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Showers and thunderstorms continue this evening ahead of the cold front that is just starting to move through the region. Still plenty of moisture out there per the 00Z sounding showing 1.8 inches of PWAT. OHX radar estimating a few spots seeing 1-2 inches of rainfall in an hour, so these showers are still packing a punch. With widespread saturated grounds, it will not take much to start seeing some flooding concerns. CAMs bring additional showers and thunderstorms overnight after slowly dissipating/weakening this current line of showers over the I-65/I-40 corridors as it moves east. However, the latest HRRR shows this line maintaining strength as it heads towards the Plateau, then weakens a bit. Either way, any rainfall this evening will just add more saturated ground for the next round of rain overnight into Wednesday morning and keep the flooding threat going. && .AVIATION... 00Z TAF DISCUSSION. Showers and a few thunderstorms will move through the area this evening and again overnight into the morning Wednesday. Cigs will drop to MVFR and IFR at all terminals overnight, with some periods of LIFR cigs possible. MVFR/IFR vis possible with showers/storms as well as some patchy fog overnight. After a cold front moves through this evening into the overnight hours, northwest winds will pick up to be around 10 to 15 knots gusting up to 25 knots at times especially after midnight through the end of the TAF period. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Barnwell AVIATION........Barnwell
Area Forecast Discussion
National Weather Service Reno NV
208 PM PDT Tue Sep 21 2021 .SYNOPSIS... Warm and dry conditions are expected through Wednesday with slight cooling on Thursday. Areas of haze and smoke will once again drift back into parts of the region today through midday tomorrow. An area of low pressure moving through the area tomorrow will bring increased southwest winds that should push most smoke out of the area. A slight chance for an isolated shower or two are still possible by Sunday over the eastern Sierra of Mono County but confidence remains low. && .DISCUSSION...through early next week... * CHANGES: Only showers and possible thunder chances were retained for a small portion of higher terrain in Mono County for Sunday. A low pressure system pressing east into the Pacific Northwest west will drag the weak cold frontal boundary across the northern Sierra into western Nevada. No precipitation will accompany this system but it will tighten thermal gradients enough over the region to bring breezy conditions tomorrow afternoon to the above mentioned areas. Wind gusts will range between 20-30 mph with some gusts to 40 mph higher Sierra ridges. Winds are still expected to diminish going into the evening. Also, look for one to three hours of critical fire weather conditions over parts of the Sierra into far western NV during this forecast period. These conditions will not be widespread enough for any highlights. It is significant enough to emphasize the usual fire weather concerns seen most of this parting summer period. Winds look to be mostly light the remainder of this week with a NE-E flow increasing over the Sierra and western NV as higher pressure exerts its influence Thursday into Friday. Modest westerly breezes will make a return entrance by this weekend with ensemble guidance poking at stronger breezes once again increasing by the middle of next week. Outside the wind factor, smoke and haze from Sequoia/Kings Canyon fires will be added to still active Caldor fire and continue to be a nuisance through this weekend. Downwind areas over the Sierra and far western NV could see air quality impacts through the foreseeable future. However, most areas should not have substantial air quality impacts through this forecast period with the exception for the Mammoth area, which could still see degraded air quality due to its close proximity to the more active fires in the central Sierra. This smoke should be pushed more east as winds increase tomorrow afternoon. The brief return of a northeast- east flow should keep smoke from existing active fires out of our region Thursday and Friday. Sunday could still see a few showers with possible thunder chances developing over higher elevation areas near the Sierra crest/White Mountains in Mono County. Both available moisture and instability will be the limiting factor for any developing storms. Dont expect any significant precipitation from these storms as well. Temperatures will once again warm into the 80s for most lower elevations and mid-upper 70s for Sierra valleys going into the weekend. Thursday could be a few degrees cooler in the NE-E flow expected behind the earlier trough passage. Ensemble guidance is hinting at a pattern chance by the middle of next week so stay tuned for further details. -Amanda && .AVIATION... This afternoon winds from the SW-W will gust 15-20 kts across much of far western NV. Smoke trapped in the Central Valley of California and the western slopes of the Sierra could filter across the crest later this afternoon and create slantwise VIS issues for Sierra terminals as well as KCXP-KMEV. Into west-central NV and Mono- Mineral counties, lower-level flow forecasts remain light for much of the day bringing an influx of more smoke over those areas. Forecast smoke guidance also shows a change for southern Mono County including KMMH as simulations bring thicker, lower smoke layers early tomorrow morning. Hi-Res HRRR model guidance continues to thicken smoke back into the Tahoe Basin/KTVL later tonight as well. For Wednesday, increasing gusty southwest winds to 20-25kts, locally to near 30kts, are likely in the afternoon and evening mainly north of US-50. Turbulence is also expected to increase along and east of the northern Sierra crest through tomorrow as stronger down/up drafts in the area of KRNO could impact arriving and departing commercial airline traffic. Increasing winds tomorrow afternoon should mix out most smoke affecting area terminals. -Amanda && .FIRE WEATHER... * Warm and dry with little to no rainfall chances the next 7 days. * Breezy winds Wednesday may lead to localized areas of critical fire weather conditions. Breezy winds Wednesday remain on track as a system passes to our north. Expect gusts in the 25-35 mph range during the afternoon and evening hours. In the higher elevations of the Sierra and northeast California, peak ridge level winds may touch 45 mph. Combine the wind with dry conditions there could be localized areas of critical fire weather conditions especially the Sierra Front. Beyond Wednesday winds will turn to the north and east for Thursday but should be rather light. There could be a brief period of dry- gusty northeast to east winds along the Sierra Crest Thursday AM. Brong && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...
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