Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/14/22

Area Forecast Discussion
National Weather Service Gray ME
1139 PM EDT Tue Sep 13 2022 .SYNOPSIS... An area of low pressure will bring high coverage of showers and storms through the area into the early overnight hours. Some of these storms later this afternoon and evening may be strong to severe with damaging winds and torrential downpours possible. This system will be followed by much cooler, drier, and gusty conditions for the end of the work week with high pressure building into New England. The high remains in control through the weekend, then drifts offshore by early next week with ridging building across the Northeast. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Prev Disc... Showers and scattered thunderstorms with heavy rain continue to move east and weaken with time. This is reflected in the latest HRRR solutions. In the meantime, fog will continue to break out before the westerlies kick in with drier air later tonight. Low cloudiness and fog will be most prevailent in Maine. Have made minor adjustsments to the near term portion of the forecast with temperatures, dew points and winds this updated package. Also adjusted pops to account for latest radar imagery and mesoscale models. Prev Disc... Continuing to monitor line of showers and thunderstorms crossing through New Hampshire as of 2222Z. This system will continue to be slow moving with training taking place in a couple areas. This will elevate the threat of localized flooding across portions of the forecast area with many flood advisories already issued over western portions of New England. The airmass will continue to gradually stabilize across portions of the region as we head through this evening. Have updated the near term portion of the forecast for temperatures, dew points and winds. Also, fog will be problematic this evening, especially across southern Maine. Drier air will enter the region later tonight however on increasing westerly winds. Prev Disc... After some shower activity this morning and early afternoon, we are in a temporary lull for a couple of hours before things get active within the next few hours. So have lowered PoPs through 5 PM or so to account for this. Otherwise, not much has changed with expectations for the rest of this afternoon and into this evening. Latest CAM guidance continues to show showers along with scattered storms developing and crossing into western NH in the 5-7PM timeframe as an upper trough currently centered over Lake Erie gradually approaches New England. While this occurs, wind shear profiles will also increase as a 110 kt 250mb jet streak overspreads southern New England, putting most of the forecast area in the left exit region. So while we will have the lift and shear (0-6km shear approaching 40-50 kt this evening), the question mark is the instability. So while wind shear will be impressive over most of the area, the latest runs of the HREF along and NAM are highlighting the southern half of NH and more specifically southwestern NH with SBCAPE approaching 1000 J/kg by early this evening. So the more favorable shear/overlap will be across this area, suggesting the higher threat for strong to severe storms with damaging wind gusts and torrential downpours as the primary hazards. We also cannot rule out a brief tornado with HREF ensemble means painting 0-1 km SRH across southern NH. Showers and storms will continue to push to the north and east through the evening, but instability will be gradually waning with time, especially with eastward extent. So while the threat for strong to severe storms still exists across Maine, it does appear to be lower. Convection will come to an end from west to east through the evening and early overnight hours as drier air pushes into the area while the upper trough and its surface low start to lift up the St. Lawrence Valley. However, some upslope shower activity will likely linger across the mountains. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... The mid and upper levels dry out in response to a deepening W-NW flow as the upper trough and associate surface low move up the St. Lawrence River Valley. However, there will be quite a bit of low- level moisture leftover toward the mountains, and with this moisture and flow pattern, more cloud cover and scattered upslope showers will continue through the day. Some of the clouds may work their way down into the foothills and points farther south, but no precip is expected across these areas with skies ranging from mostly to partly sunny. It will also be a breezy out with a tight pressure gradient and once we start mixing down the higher winds from aloft by late morning and into the early evening hours. Forecast soundings support gusts generally around 25 mph, but we could see a few closer to 30 mph. Max temps will be warmest across coastal and southern areas with the winds preventing a seabreeze, and these areas will be in the upper 70s to around 80 degrees. A little farther inland, temperatures will taper off into the low-mid 70s, and toward the mountains, the clouds/showers will keep temperatures cooler and in the 60s. The upslope showers should continue into portions of the overnight hours until a mid-level shortwave trough sends a strong but dry reinforcing cold front through the area. A much cooler and drier airmass will quickly advect in behind this front, and low temperatures are expected to range from the upper 40s to lower 50s across the south the lower 40s across the north. A few spots across northern areas may even reach the upper 30s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Overview... Low pressure continues to move away from New England on Thursday as high pressure builds in from the west, setting up conditions for a breezy day. Winds ease Friday as the high continues to build in on Friday. The high passes across New England on Saturday, and then moves offshore on Sunday. Ridging builds across the Great Lakes and the Northeast by late in the weekend and early next, bringing a moderating trend and seasonably warm temperatures back to the area. A weak system brings an increased chance of POPs early next week, most likely across northern areas. Details... The pressure gradient between the departing low pressure center and the incoming high pressure brings northwesterly winds gusting to near 30mph on Thursday. Combined with daytime highs in the low 50s across the north and 60s across the coastal plain, it will feel like the most fall-like day so far for many. Temperatures then fall into the 30s and 40s across the area Thursday night, with low to mid 40s expected all the way to the coastline. As the high continues to build in on Friday the wind will ease and temperatures moderate slightly, especially across northern areas. As the high crosses overhead and winds settle Friday night, temperatures fall into the 30s across most interior areas. Frost is possible across northern zones and inland sheltered valleys. Temperatures moderate further on Saturday as the high gradually moves offshore. Temps climb back into the low to mid 70s across the coastal plain, and mid to upper 70s by Sunday. As the ridge builds, low 80s likely make a return to southern areas early next week. A weak warm front gradually passes through New England early next week, which brings the increased chance of POPs with the warmer temperatures. The progression of this system remains somewhat uncertain at this time, but either way it doesn`t look to be a very potent system. Once this passes through, the pattern signals building warmth into midweek as the ridge continues to build. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... Short Term...Areas of fog will continue to develop tonight. However, VFR conditions should gradually return from west to east from late this evening through tonight as drier air moves into the area. The exception may be HIE, where scattered showers and lower ceilings may linger into Wednesday afternoon. Otherwise, west winds will gust to around 25 kt from Wednesday morning into the early evening hours. Long Term...Gusty northwest winds up to 30kts are likely on Thursday. VFR conditions are expected at most terminals, but MVFR ceilings are possible at HIE in the northwest flow. Winds ease Thursday night with mainly VFR conditions expected through the weekend. Some valley fog is possible at night Friday through Monday. Scattered showers are possible early next week. && .MARINE... Short Term...Fog will remain possible across the waters into most of tonight across the waters. Otherwise, conditions will deteriorate late tonight as west to southwest winds increase into Wednesday early afternoon. Gusts to around 25 mph are expected along with seas building to around 5 ft. Conditions may briefly fall below SCA levels later Wednesday afternoon, but will likely need another SCA by Wednesday evening/night as northwest winds ramp right back up behind a strong but dry cold front crosses through waters. Long Term...SCA conditions are likely on Thursday with gusty northwest winds up to 30kts. Conditions then ease Thursday night as high pressure builds across the waters and brings more tranquil conditions for Friday and the weekend. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 4 AM to 8 PM EDT Wednesday for ANZ150>154-170-172-174. && $$ NEAR/SHORT TERM...Cannon LONG TERM...Clair
Area Forecast Discussion
National Weather Service Lincoln IL
1100 PM CDT Tue Sep 13 2022 .SYNOPSIS... Issued at 244 PM CDT Tue Sep 13 2022 The stretch of dry weather will continue through late week as subsidence builds in behind a departing weather system. Meanwhile, temperatures will exhibit a hearty warming trend through this weekend as daily temperatures surge into the mid-to-upper 80s beneath a strong, late-summer heat ridge. && .UPDATE... Issued at 800 PM CDT Tue Sep 13 2022 00z surface map indicated broad high pressure stretched across the Midwest and Ohio Valley. Under the ridge winds were light and dewpoints were in the upper 50s to lower 60s. Latest IR satellite imagery shows the cloud deck that had persisted over eastern IL much of the day has almost completely pushed east of the state line. Main forecast concern is fog potential late tonight. High resolution guidance is pointing to areas east of I-57 for areas of fog, with a low potential for dense fog along our far eastern row of counties along the Indiana border. Conceptually this makes sense since these areas did not mix out low level moisture this afternoon, so have increased fog wording east of I-57. The primary fog timing is from 3-8 am, and the eventual need for a Dense Fog Advisory cannot be ruled out for the far eastern CWA. Farther west, patchy shallow fog is possible but is not expected to have a meaningful impact on visibility. Good radiational cooling will promote another cool night, with lows in the low/mid 50s. && .SHORT TERM...(This evening through Wednesday) ISSUED AT 244 PM CDT Tue Sep 13 2022 While the large upper low was centered near Buffalo NY early this afternoon, the fringes of the circulation continues to bring cloud cover east of I-57, though it has appeared more diurnal as of late. However, RAP layer humidity plots show this should largely be east of the Indiana border by sunset. Forecast soundings in eastern Illinois do suggest the possibility of some ground fog after midnight, with latest NBM probabilities showing 20-30% chances of visibility below 3 miles. Will include a mention of patchy fog in the two columns of counties along the Indiana border, as well as north of Peoria where some of the heavier rain occurred over the weekend. Otherwise, clear skies to prevail overnight, with lows mainly in the lower 50s. Can`t rule out some upper 40s in the western fringes of the forecast area, where dew points this afternoon have dropped into the 40s. High pressure will slowly drift east through Wednesday, keeping our weather quiet. The thicker smoke layer to our west will make an eastward push, though vertically integrated smoke forecasts off the HRRR favor more of an impact across northern Illinois, thus any corrections to sky cover projections have been fairly minimal for this forecast package. With more of a southeast flow setting up, temperatures should reach the lower 80s for highs. .LONG TERM...(Thursday through Tuesday) ISSUED AT 244 PM CDT Tue Sep 13 2022 Low-level winds will veer southerly by Thursday as the upper-level ridge axis builds across the Mid-Mississippi Valley and the center of surface high pressure drifts eastward. This process will help boost temperatures into the low-to-mid 80s as the return flow advects warmer air in from the Southern Plains. The stretch of dry and progressively warmer temperatures will continue through this weekend as mid-level ridging remains locked in place over the SE U.S. This feature will help keep central Illinois entrenched in southwesterly flow, and ultimately on the periphery of any convective activity as the majority of shortwave impulses look to skirt by to the north and west. Trends over the past couple forecast cycles have decreased PoPs and QPF over our CWA, with the better signal coming over SE Iowa and N Illinois; closer to the shortwave impulses. The main message into early next week is the continued unseasonably warm temperatures. NBM guidance is offering daily highs near 90 each day Sunday through Tuesday as heat builds beneath an anomalous late-summer ridge. The forecast also calls for breezy and continued dry conditions as the stubborn ridge helps deflect convective activity north and west of our area. It`s not until the middle-to-late stages of next week that the ridge shows signs of breaking down. About 1/3 of the members of the grand ensemble cluster toward a solution that keeps the heat ridge anchored over the Deep South. This would keep central Illinois hot and dry into late next week. Meanwhile, the other 2/3 of members cluster toward a solution that sends robust shortwave energy digging through the Plains, effectively breaking down the ridge as an approaching front brings on a wetter and cooler period into late next week. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1100 PM CDT Tue Sep 13 2022 Guidance has trended toward more widespread fog late tonight, with higher probabilities of IFR fog at KCMI. This is where the lowest visibilities are forecast and have a TEMPO group for 1SM at KCMI. Higher visibilities are forecast farther west, but at least a few periods of MVFR conditions are possible, centered around 09-13z. Otherwise, clear skies and light/variable winds prevail next 24 hours under a high pressure ridge. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...25 SYNOPSIS...MJA SHORT TERM...Geelhart LONG TERM...MJA AVIATION...25

.SHORT TERM...(This evening through Wednesday night) Issued at 247 PM CDT Tue Sep 13 2022 Continued quiet weather is anticipated tonight before a change in the weather pattern occurs on Wednesday. An upper level ridge, currently centered over the High Plains, will progress east tonight. The HRRR vertically integrated smoke model shows that while the smoke will not be as dense as it was today, it will still linger aloft. Very little should be at the surface and major impacts are not expected. This smoke should help prevent some radiational cooling overnight. A surface trough along the front range will remain in place and cause winds to shift to the south, drawing warm air from Texas north into Nebraska through the night. These factors combined with forecasted daytime highs in the 90s this afternoon will moderate overnight temperatures with lows in the 50s. Warm temperatures are on tap again tomorrow as southerly warm air advection carries on. However, this morning`s sounding showed 850 mb temperatures of 29 degrees Celsius, but model soundings for tomorrow show 850 mb temperatures closer to 22 Celsius in the morning and weaker low level lapse rates. The advancing surface trough will also bring greater cloud cover. Therefore, temperatures will be slightly lower than today but still around 10 degrees above normal. A tightening pressure gradient between the surface trough in eastern Colorado and high pressure over the Indiana/Ohio will create stronger southerly winds tomorrow, gusting to 30 knots in some areas. Hot temperatures, low relative humidity, and stronger winds do create some fire weather concerns for tomorrow. Please see the fire weather discussion for more details. Southerly to southwesterly flow will bring a subtle increase in moisture into Nebraska, some of which originated from the remnants of tropical storm Kay in the Pacific. An upper level shortwave trough ahead of a low over the Pacific Northwest will move east over the Rockies and reach Nebraska by the afternoon. As the surface trough and upper level support converge, the possibility for thunderstorms returns to the forecast area. Severe storms are not expected as CAPE is less than 1000 J/kg and surface to 6 km shear less than 20 knots, but some storms may be strong. One limiting factor may be moisture as advection may not be strong enough for widespread storm development. Surface relative humidity will be between 20 and 35 percent for most areas with dew points in the 40s to 50s. Rain chances do appear to improve later in the night as the trough advances east into areas of better moisture. .LONG TERM...(Thursday through Tuesday) Issued at 247 PM CDT Tue Sep 13 2022 Additional rainfall chances exist Thursday through Saturday as an upper level trough deepens over the West Coast and several shortwave troughs will move east ahead of this feature. A surface trough will slowly move east through Nebraska, providing a lifting mechanism for storm development. The possibility for severe weather appears low at this time, although there is an indication of increased CAPE on Friday and Saturday which may be the best chances for stronger thunderstorms. Exceptionally hot weather is possible again early next week. A trough over the western United States will continue to draw warm air into the Great Plains. Long range guidance is picking up on highs 20 to 30 degrees above normal, through these temperatures are moderated in the forecast through bias correction. Temperatures should begin to cool once again on Tuesday as a cold front approaches from the northwest. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 620 PM CDT Tue Sep 13 2022 VFR conditions are expected to prevail through tomorrow evening. Scattered thunderstorms are anticipated across much of western and north central Nebraska tomorrow afternoon, though confidence remains too low for any TS mention at both LBF and VTN for now. Winds remain southerly and increase tomorrow afternoon, with gusts of 25 to 30kts anticipated. && .FIRE WEATHER... Issued at 256 PM CDT Tue Sep 13 2022 The return of summer-like temperatures and high pressure overhead have resulted in very dry air today, especially across western Nebraska where humidity values fell into the lower teens. The lack of gusty winds precludes any critical fire weather concerns. Elevated fire weather continues tomorrow, but mainly for gusty winds. Moisture begins streaming into the region, which holds humidity above critical thresholds, but southerly winds will gust above 30 mph at times. Isolated to scattered thunderstorms will affect the Sandhills from late afternoon through the late evening hours, then again on Thursday and Friday. Potential for wetting rain seems to be localized, although more widespread precipitation is possible Thursday evening across north central Nebraska (zone 209, eastern 208). A cool front will also result in a rapid wind shift from south to northwest on Thursday. Looking ahead, temperatures rebound and humidity drops again Sunday into Monday. Depending on winds, critical conditions are possible, especially Monday. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Meltzer LONG TERM...Meltzer AVIATION...Brown FIRE WEATHER...Snively
Area Forecast Discussion
National Weather Service San Francisco Bay Area
535 PM PDT Tue Sep 13 2022 .SYNOPSIS...Cooler than normal temperatures are expected to persist across the region through late week with breezy onshore winds at times. There will also be the potential for light rainfall late in the weekend followed by the development of offshore winds and slightly warmer temperatures early next week. && of 02:01 PM PDT Tuesday...Mostly sunny sky conditions prevail over the region with a few to scattered low- level clouds bumping up again the North Bay and San Mateo County coastlines as well as the East Bay Hills. Satellite imagery is showing even these clouds beginning to dissipate as conditions begin to dry out in the boundary layer. Even with the abundant sunshine, temperatures are running a few to as much as 10 deg F cooler compared to 24 hours ago. This is in response to the cooling air mass aloft as a mid/upper level low pushes inland over Washington. A similar pattern will persist into Wednesday with temperatures below seasonal averages, generally running in the mid/upper 60s at the coast to mid 70s inland. Additionally, the HRRR and other short- range guidance do show low-level clouds developing once again late tonight before spreading locally inland. Breezy onshore winds are also likely to persist through midweek, with gusty winds in the favor passes and coastal gaps. Only slight warming is anticipated on Thursday and Friday with a few interior locations peaking in the lower 80s as broad troughing persists over the region. By Saturday the mid/upper level pattern will begin to change with a low pressure system developing over the Bay of Alaska. The forecast models are becoming better aligned with the track of the mid/upper level low dropping down the Pacific Northwest coast and eventually down the California coast this weekend. As such, a frontal system is likely to push southward into northern California and interact with precipitable water values close to an inch. With enough forcing, may see light precipitation spread from north to south across the region on Sunday. Currently, it looks as though rainfall amounts will range from a few hundredths of an inch to a tenth of an inch in the coastal hills. This is still an evolving pattern with details likely to change in the coming days. The next impact of note would be once the aforementioned mid/upper level system shifts inland early next week. Forecast models continue to indicate a reinforcing trough dropping into the Pacific Northwest and then down the intermountain West as an inside slider. This pattern would be favorable for the development of offshore winds across the greater San Francisco Bay Area (thinking North Bay and East Bay hills/mountains). The timing of this still appears to be in the Tuesday to Wednesday timeframe with the details on strengthen of potential offshore winds still in question. The good news is we have a few days to monitor and fine tune the forecast. && of 5:00 PM PDT Tuesday...For the 00Z TAFs. Mainly clear skies prevail this afternoon with the exception of a few patches of stratus lingering along the coast. A deep marine layer coupled with a moderately strong onshore gradient will result in the return of stratus a bit sooner, between 04z-06z this evening and the expectation of a later burn-off, around 16z-18z tomorrow morning. Coastal terminals may see stratus linger till around 19z. Vicinity of KSFO...VFR conditions persist across area terminals with patchy stratus spreading inland through coastal gap. Anticipate a slightly earlier return of the status this evening with gusty onshore flow. MVFR cigs expected to return to area terminals between 04Z-06Z with winds easing overnight. A deep marine layer and onshore flow may keep cigs around through Wednesday morning before clearing in the afternoon. KSFO Bridge Approach...Similar to KSFO. Monterey Bay...VFR conditions prevail through the evening, with stratus redeveloping tonight. MVFR likely but IFR possible. Breezy NW winds this afternoon, easing by evening. Late clearing Wednesday morning. && of 03:08 PM PDT Tuesday...Some strong gusty winds through the Golden Gate, along coastal jet regions south of Pigeon Point, and along the Big Sur coast through tonight. Hazardous conditions for smaller vessels can be expected where the stronger winds develop. Winds will diminish tonight into Wednesday, but then redevelop Thursday through the end of the week. A southerly swell of 2 to 4 feet at 12 to 14 seconds continues. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...SF Bay until 9 PM SCA...Mry Bay until 9 PM SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM && $$ PUBLIC FORECAST: RGass AVIATION: CW MARINE: Lorber Visit us at Follow us on Facebook, Twitter, and YouTube at:
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 321 PM CDT Tue Sep 13 2022 Upper-level ridging will continue to move over the central CONUS. Smoke originating from fires across the northwestern U.S. will continue to pass overhead but according to the recent runs of HRRR near-surface smoke, is not anticipated to mix down to the surface. This should create some photogenic sunrises and sunsets over the next couple of days. Temperatures will remain about 10 degrees above normal for this time of the year through the next 7 days. Upper/mid-level flow becomes southwesterly by late in the week as a broad trough moves into the the western U.S. This will send a series of weak disturbances into the region with off and on chances for showers and thunderstorms beginning as early as Wednesday night and continuing into the weekend. QPF through the period does not look overly impressive and certainly not a drought-buster by any means. Better precipitation chances look possible into next week as a large western upper trough begins to eject into the central U.S. pushing a strong cold front into the central Plains. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 616 PM CDT Tue Sep 13 2022 VFR conditions will prevail through the forecast period with LLWS expected from around midnight into mid-morning on Wednesday. From late morning through afternoon, southerly surface winds will strengthen to 12-15 kt with gusts of 20-25 kt. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Kern AVIATION...Mead
Area Forecast Discussion
National Weather Service Spokane WA
439 PM PDT Tue Sep 13 2022 .SYNOPSIS... Clusters of slow moving thunderstorms will develop over north central Washington this afternoon and spread into eastern Washington and north Idaho overnight. Locally heavy rain will be possible over the steep terrain of the north Cascades and Okanogan Highlands. Redevelopment of showers and thunderstorms is likely Wednesday along the Canadian border. The combination of rain, cool temperatures, and a subtle increase in west winds should bring gradual improvements to our air quality Wednesday into Thursday. The weekend will be cooler with daytime temperatures in the 60s and morning lows in the 40s and a few 30s. && .DISCUSSION... This evening and through the night: Showers and thunderstorms over north central Washington will increase late in the afternoon into the evening as an upper low over the Olympic Peninsula (as of 2 PM) slowly migrates east through the night. Through the night, look for scattered showers and thunderstorms to spread into eastern Washington and north Idaho. While our precipitable water values and surface dewpoints aren`t particularly high, the combination of upper level difluence and weak mid-level flow will contribute to an environment conducive for slow moving showers and thunderstorms, mainly in north central Washington. A Flash Flood Watch is in place for Chelan, Okanogan, Ferry, and Stevens counties this afternoon into Wednesday. Widespread flooding is not anticipated, but slow moving cells that develop over flood prone areas may cause problems with rock/mud slides and rapid rises on creeks and streams. Steep terrain, urban areas, and burn scars are a particular concern. While the rain may cause some localized problems, precipitation will benefit our region which has been very dry since mid July. Wednesday: During the day Wednesday, our slow moving upper low will pivot across northeast Washington into southern British Columbia. High resolution models predict a lull in shower activity in the morning with a redevelopment for our counties along the Canadian border during the afternoon. Similar to today, atmospheric moisture and instability will be sufficient for thunderstorms development. Once again, slow moving cells capable of locally heavy rain will be monitored closely in Okanogan, Ferry, and Stevens counties. Thursday and Friday: A weak upper level trough will persist over the Pacific Northwest Thursday and Friday. With the departure of our upper low Wednesday night, precipitation chances will be very low on Thursday with a slight increase up to 20 percent along the Canadian border on Friday afternoon. Seasonal temperatures will be on tap with highs in the 70s and lows in the 40s and 50s. Saturday through Wednesday: The upper level weather pattern begins to take on a more Fall-like pattern as we head into the weekend. The trajectory of where this upper level trough is originating in the Gulf of Alaska will bring southward much cooler air. The weather system has little signature of moisture with the percentile of precipitable water showing about normal for this time of year. The cluster analysis of ensemble members by Sunday is a three-way tie between deepening the Low off shore, a weaker longwave trough down the West Coast, or a digging trough into Oregon. The EC ensemble favors more of the longwave trough extending southward and swinging through the Great Basin over the weekend; a more progressive solution. The GFS and Canadian ensembles would be more in favor of a deeper, cut-off Low off the California coast. What would this mean for our sensible weather in the Inland Northwest? This could lead to cooler, more unstable weather over the weekend with a dry boundary layer and high level moisture (partly cloudy skies). While uncertainty is quite large for exactly which model solution to lean harder on, the overall agreement to a more troughy and cooler pattern seems probable. CPC has introduced a slight chance for below normal temperatures as we head out into the far extended (next week). This time of year, mid September, brings normal daytime high temperatures in the low 70s and right now the forecast is showing upper 60s. /Dewey && .AIR QUALITY AND SMOKE... The combination of precipitation, higher humidity, and temperatures trending cooler than they were the last few weeks should bring gradual improvements to air quality for much of the Inland Northwest. Over the next 24 to 36 hours, parts of Idaho, southern British Columbia, northern Washington, and northeast Oregon should experience enough shower activity to wet a significant number of our active fires. And a persistent upper level trough should lead to several days of a prevailing west or southwest flow. While late summer morning inversions will be slow to break leading to thick smoke near fires, in general the combination of wetter and cooler conditions and a cleaner west flow should lead to gradual improvements in our smoky skies this week into the weekend. /GKoch && .AVIATION... 00Z TAFs: Scattered showers and thunderstorms will accompany the passage of a slow moving upper low this evening through the overnight. VCSH have been included at most TAF sites this evening. High resolution models predict the development of a band along the WA/ID border between 10-15z which is enough to include prevailing showers at Pullman and Coeur d`Alene. A gradual improvement in the visibility is predicted through the night as the upper low crosses the Cascades leading to a cleaner west wind through the night and into the day Wednesday. Visibility forecasting with smoke is a low confidence endeavor. The HRRR smoke model is frequently better at forecasting the arrival of smoke than the departure of it. /GKoch && .PRELIMINARY POINT TEMPS/POPS... Spokane 53 74 50 77 50 74 / 40 20 0 0 0 0 Coeur d`Alene 52 74 50 77 48 73 / 40 40 0 0 0 0 Pullman 47 73 45 73 43 71 / 40 40 0 0 0 10 Lewiston 59 80 56 80 54 78 / 30 30 0 10 0 10 Colville 43 73 41 78 41 75 / 50 60 10 0 10 10 Sandpoint 48 71 45 74 45 71 / 30 50 10 0 10 10 Kellogg 55 71 53 73 52 71 / 20 50 10 0 10 10 Moses Lake 50 78 49 80 48 76 / 40 10 0 0 0 0 Wenatchee 56 76 57 78 54 74 / 40 10 0 0 0 0 Omak 54 78 53 80 52 78 / 70 40 10 10 0 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Flood Watch through Wednesday evening for Central Chelan County- Okanogan Highlands-Okanogan Valley-Upper Columbia Basin- Wenatchee Area-Western Chelan County-Western Okanogan County. Flood Watch through Wednesday evening for Northeast Mountains. && $$
Area Forecast Discussion
National Weather Service Reno NV
147 PM PDT Tue Sep 13 2022 .SYNOPSIS... Smoke from the Mosquito fire will continue to produce air quality and visibility impacts across portions of western Nevada and northeast California. Shower and thunderstorm chances will shift eastward this afternoon and tomorrow with localized areas of heavy rainfall possible from Mono County into the eastern extents of Pershing and Churchill counties. Seasonably cool temperatures with freezes possible in mountain valleys each morning. An early season cold front this weekend is expected to bring below average temperatures, gusty winds along with low elevation rain and mountain snow showers. && .SHORT TERM (Through Wednesday Night)... * The main topic of discussion will continue to be the degraded air quality from the Mosquito Fire burning in western Placer and El Dorado counties. While it`s safe to conclude that not everyone in the region will experience smoke impacts, the location of the fire and prevailing winds will keep many of our larger metropolitan areas along the I-80 corridor in a favorable location for haze/smoke as long as the fire keeps burning. In the near term, while we will see some improvement early this afternoon due to afternoon mixing, an uptick in fire behavior due to peak afternoon heating along with an increase in southwest transport winds will likely transport a concentrated smoke plume from Placer Co north into SE Plumas by mid/late afternoon. Around sunset, we should see the smoke establish itself into portions of western Nevada - primarily impacting southern Washoe (including Reno/Sparks) before traversing eastward into portions of the Basin and Range. Check out for the latest air quality in your area including short-term AQI forecast for specific locations. * However, we obviously cannot forget about the topic of showers and thunderstorms as well! Not much change in forecast thinking from the overnight hours... High resolution CAM guidance continues to be in good agreement on scattered to numerous showers and storms firing up this afternoon along the eastern Sierra and portions of western Nevada, primarily south of US-50 and outside of Reno/Carson (although chances aren`t zero). Despite ample moisture (PWATs 0.75-1.00 inches), HREF neighborhood probabilities keep the chances of exceeding 1hr flash flood guidance generally 5-10% across southern Mono and Mineral counties due to the storm motion of around 15 knots. Nevertheless, quick but high rain rates on burn scars or steep terrain always creates a concern for flooding due to their localized lower thresholds. Finally, any convection that does sneak north of US-50 in eastern Churchill/Pershing will have a higher likelihood of strong outflows due to higher DCAPE values off to the north. Another round of convection can be anticipated Wednesday afternoon, but more isolated to scattered in nature and generally along or east of US-95 and US-6. Quicker storm motion (around 20kts) compared to today will lower the chance for flash flooding even further as well. Oh yes, if you happen to be hiking above 11,000-12,000 feet, some snow showers will be possible through the period in places like the White Mountains and high eastern Sierra; expect minimal accumulation - if any ... * Nothing unusual in terms of temperatures in the short term period. Well, compared to what we`ve seen lately, I guess below average is something to write home about! On Wednesday, highs around 80 in western Nevada Valleys with low 70s in Sierra Valleys will feel rather pleasant. A freeze is possible tonight in some of our colder Sierra valleys, but more widespread sub-freezing temps can be expected Wednesday night as several valleys in the Sierra will dip into the upper 20s. Hooray for the taste of Fall! -Dustin .LONG TERM (Thursday Onward)... For Thursday and Friday, we`ll maintain a cool, southwest to zonal flow aloft. This will provide the area with slightly below normal temperatures with mostly low 80s for the valleys and low 70s in the Sierra. There still is a slight 15% chance of lingering showers in Mono and Mineral counties on Thursday due to left over moisture. The big question for the region will be possibility of continued poor air quality due to surrounding wildfires. Unfortunately, there is no simple answer to this question. While near-term models show light west to southwesterly winds (which would transport smoke into western NV/Tahoe), it`s very dependent on the amount of smoke generated by the Mosquito Fire. For those of you tired of summer (my hand is raised), a big pattern change is in store by the weekend through the end of the forecast period Tuesday. The long-term ensembles are in favor a deep trough dropping south from the Gulf of Alaska into the western U.S. But, the latest WPC Cluster analysis shows considerable differences between the ensembles in timing and strength of the aforementioned trough, especially after Saturday. What is for certain, temperatures will fall well below average by Sunday, and remain below average through the at least the middle of next week. Southwest winds will increase ahead of this trough, with the strongest gusts possible (35+ mph) on Saturday and Sunday. Finally, precipitation chances will increase between 25-35% from Saturday through Monday. Given the considerable drop in temperatures, some of this precipitation could fall as snow for the higher elevations (~7,500-8,000ft). Stay tuned to the upcoming changes! -McKellar && .AVIATION... * The latest HRRR smoke model is not as aggressive with the smoke as the past couple of afternoons, with the KRNO-KTRK terminals on the southern edge of the main plume trajectory. We are looking at the potential for primarily VFR conditions for KTRK-KRNO (but degraded conditions at KRTS). While there may be some slantwise visibility concerns, areas to the north and south including KTVL/KCXP/KMEV/KMMH and KSVE also appear to remain VFR with much less dense smoke than recent days. * The shower and t-storm potential has shifted eastward this afternoon-evening, with west central NV around 35-45% chance at KLOL/KNFL, southward to KHTH-KMMH about 60% chance and less than 20% elsewhere. Primary concerns will be MVFR-IFR conditions from heavy rain and localized dust/smoke, outflow wind gusts to 40 knots, and lightning. By Wednesday, the potential for storms trends down with about a 25% chance for KMMH-KHTH and 10% or less elsewhere. -Edan && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$