Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/22/20

Area Forecast Discussion
National Weather Service Birmingham AL
712 PM CDT Fri Aug 21 2020 .UPDATE... For 00Z Aviation. && .SHORT TERM... /Updated at 0145 PM CDT Fri Aug 21 2020/ Through This Evening. No major changes were made to the short term forecast this morning. On visible satellite imagery, the closed upper low can be seen rotating over Central MS. We had numerous light showers and low clouds over the northern/northwestern portions of Central AL this morning which did slow surface heating in those areas, but forecast temperatures are largely on track as the cloud deck has broken apart. Highs will range from near 80 north to mid 80s south. Additional scattered to numerous showers/storms will develop this afternoon as the PBL continues to destabilize. There is more instability across our south where these areas did not see as much rain and cloud cover earlier today. Therefore, will maintain the afternoon Marginal Risk for a couple severe storms capable of isolated, strong downbursts as SBCAPE values reach 2000-2500 J/kg while a slot of dry mid-level air surges northeastward per RAP mesoanalysis. The threat will be highly conditional as the drier air might suppress development in the first place, and latest CAMs seem to be indicating this. As a result, I lowered PoPs in our southeastern quadrant with highest PoPs focused in the better moisture pool across our north and northwest. However, any storms that develop among this drier, unstable air will have the potential to produce strong, gusty winds. Tonight Through Saturday. With the proximity of the upper low to Central Alabama tonight, scattered showers and thunderstorms will linger well into the evening hours. If storms do develop over southwest Alabama, outflow boundaries will keep higher rain chances west of I-65. By sunrise Saturday whats left of the upper low center will likely be over northeast Mississippi. The low circulation appears to evolve into an trof by afternoon, and overall forcing is weak throughout the day. Better rain chances will reside over the far northern counties of Central Alabama, closer to trof axis. 86/58 .LONG TERM... /Updated at 0218 PM CDT Fri Aug 21 2020/ Features. Sunday and Monday. The upper trough will begin to lift northeast into the Ohio River Valley region on Sunday. Residual weak troughing, however, looks to remain from the Ohio River Valley region southwest over the Mississippi River Vally and into Deep South Texas. Mid-level ridging over the Southwest Atlantic Basin will build a bit further west into the region from the southeast. Tuesday through Thursday. The upper level ridging to the southeast will continue to build a bit more west while the mid to upper level weakness to our west slides further west, becoming positioned over the Central Plains states. Expect the upper level ridging to continue to expand over the Southeast into Thursday while an upper low is progged to develop over the Central Plains by Thursday. Tropical Considerations. Overall, we are nearing the peak of the hurricane season and now is a good time to ensure that residents have their hazardous weather plans ready and their safety kits stocked and ready. There will likely be continued fluctuations in the forecast until the systems become well-established and the environments in and around the storms become better sampled. Please continue to check back for forecast updates through the weekend along with the latest products from the National Hurricane Center. There remains considerable uncertainty with the forecast for Tropical Depression Thirteen in the Western Caribbean Sea and recently formed Tropical Storm Laura near the Leeward Islands. Model solutions are and will continue to vary and deviate from run to run, due to the current weak intensity/loose organization of the systems and limited observational information currently available at this time. The ultimate track and development of these systems will largely depend on the size, strength and location of the deep-layer ridging over the Southwest Atlantic Basin along with the position and depth of the remnant trough/weakness aloft to our west during this time period. The track of the systems will affect their intensification potential and the intensity of the system will have an influence on its track as well. We are nearing the climatological peak of the Atlantic Hurricane Season. The Gulf and Caribbean Sea are considered favorable for development with more than sufficient water temperatures and wind shear values expected to be relatively low as the deep trough over us is forecast to lift well to the northeast of the area. Forecast. Isolated to scattered showers and thunderstorms are forecast with the better coverage across the east and southeast on Sunday and Monday. Shower and storm chances will increase from the southeast, becoming scattered to numerous across the southeast counties on Monday with the rest of the forecast area experiencing isolated to scattered showers and storms. Scattered to numerous showers and storms are expected Tuesday into Wednesday with the better chances across the south and central counties. This trend looks to continue into Thursday. Expect High temperatures to range from the low to mid 80s to the low 90s through the period with the lower temperatures expected Wednesday and Thursday, coinciding with the higher rain and storm chances. Overnight lows will range from the mid 60s north to the low 70s south Sunday and Monday, followed by readings around 70 north to the low and mid 70s south Tuesday through Thursday. 05 && .AVIATION... 00Z TAF Discussion. Some parts of Central Alabama will experienced thunderstorms the next several days. The summer pattern will remain active. For this terminal forecast period, convection continues and at this writing was affecting areas near EET/TOI. There certainly remains a chance that any terminal may experience a brief thunderstorm. Reduced visibility, lightning , and wind gusts of 25kts would be possible. Handled the forecast with VCTS and if trends hold up, may introduce prevailing. Otherwise, the convection will slowly lose some intensity and coverage this evening. Not anticipating any restrictions overnight. We repeat the thunder chances again on Saturday. Winds may temporarily have a south to southwest component but overall light and variable. 75 && .FIRE WEATHER... Scattered to numerous showers and thunderstorms are expected this afternoon and evening with the better chances north and west. Expect a similar trend tomorrow with the better chances across the north tomorrow. Rain and storm chances will become maximized across the south and southeast counties on Sunday and this trend will persist through midweek next week as the airmass becomes more tropical across the area. Minimum afternoon relative humidity values will drop into the low to mid 50 percent range today and tomorrow followed by minimums in the mid to upper 50 percent range Sunday and into early next week. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 65 85 66 88 68 / 40 60 30 40 20 Anniston 66 86 67 88 70 / 40 60 30 40 20 Birmingham 67 85 69 88 71 / 40 50 20 30 20 Tuscaloosa 68 88 69 89 71 / 40 50 20 30 20 Calera 66 85 67 87 69 / 40 40 30 40 20 Auburn 67 86 68 84 70 / 40 50 30 60 20 Montgomery 68 89 70 88 71 / 40 40 30 60 20 Troy 68 88 69 86 71 / 40 40 30 60 20 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
758 PM MDT Fri Aug 21 2020 .UPDATE... Issued at 758 PM MDT Fri Aug 21 2020 Smoke will persist through tonight, Saturday, and likely well beyond. Latest HRRR smoke fields indicate smoke should get thicker later tonight and Saturday morning. Yuck. Other than the smoke, quiet weather conditions will prevail tonight. No changes to the forecast are planned. && .SHORT TERM...(This evening through Saturday) Issued at 350 PM MDT Fri Aug 21 2020 Satellite pictures are showing about 10% convective cloudiness over the CWA at this time. The clouds are over the mountains, foothills, Palmer ridge and Cheyenne ridge. The satellite pictures are also showing a decent hot spot and smoke plume coming from and off the Cameron Peak Fire in west central Larimer County. Upstream, much of the western U.S. is covered by significant smoke mainly from the vast California forest Fires. There is a fairly uniform north-northeasterly wind field in place over the plains of the CWA right now along with dew point readings in the 40s to lower 50s F. Models show the upper ridge center to push northeastward overnight with its location right over the four corners on Saturday. There is weak subsidence noted on the QG Omega fields overnight and Saturday. The low level winds should be weak drainage patterns tonight with north-northeasterlies on Saturday. Moisture-wise, it stays pretty dry overnight and Saturday with the precipitable water values ranging from 0.25 over the western CWA to 0.80 over the far eastern CWA both periods. CAPE is pretty limited this evening with some over the far east and a tad over the southern half of the high country. There is even less CAPE progged on Saturday with just a tad over the eastern border areas. The QPF fields show no measurable rainfall over the CWA tonight or Saturday. Will leave any pops out for now. The ESRL HRRR does have smoke over the CWA overnight and into Saturday. Satellite pictures concur. Will make sure the GFE grids have smoke in them for sure. For temperatures, DIA is one degree F cooler then at this same time yesterday. The ubiquitous smoke through much of the column may be taking some degrees off the temperatures. For Saturday, guidance values show readings to be 1-2 C warmer than today`s. Tomorrow looks pretty smokey so will adjust accordingly. .LONG TERM...(Saturday night through Friday) Issued at 350 PM MDT Fri Aug 21 2020 A hot ridge will remain over Colorado through the coming week. Only slight model trends today toward holding the strength of the ridge a little bit longer, with a shortwave Wed/Thu now up in southern Canada. There`s still a little erosion of the ridge starting with that shortwave passing and a surge of less hot and dry air down the east slopes behind it. There is a little...emphasis on little...moisture coming up around the backside of the ridge over Utah. This seepage should continue along with the daily mixing to gradually moisten up the ridge as the week goes on. This will mean more afternoon clouds over the mountains Saturday and maybe an isolated shower/weak storm over the central mountains. Sunday will see a little more, but still isolated and mainly dry thunderstorm coverage over the mountains and maybe some clouds coming onto the plains mid to late afternoon. For Monday through Wednesday, it just looks like a continued gradual increase in weak thunderstorm activity. By Wednesday we`ll have the climatological scattered afternoon storms over the mountains. With the air aloft not cooling at all, it will still be hard to maintain convection on the plains but low chances are in order mainly for storms slowly drifting off the mountains late in the day. The air dropping down the plains behind the shortwave for Thursday and Friday should provide increased thunderstorm activity from the Front Range eastward and a more favorable environment for storms to survive on the plains. We`ll still be fighting that warm air aloft though. Temperatures should cool, possibly even down into the 80s though the trend of a weaker shortwave might mean less cooling. It should be emphasized that while we`re showing higher rain chances later this week, for the most part we`re expecting weak storms that won`t produce much rain. There may be some dry lightning over the mountains, but coverage will be limited this weekend and by midweek the storms will be a bit wetter. There could be a bad transition day on Monday or Tuesday. Finally, the smoke from the California fires should still be bad across most of the area Saturday night, and perhaps quite a bit longer. The building ridge might shift the brunt of it mainly into Wyoming by Sunday or Monday. We`ll still have our local smoke plumes which should have more of a west to east component, so we won`t clear out, but hopefully there will be some improvement. This west to east flow from both the California and local fires will keep quite a bit of smoke around through the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 758 PM MDT Fri Aug 21 2020 Smoky skies are expected to persist through tonight and Saturday. Visibility should remain restricted and may worsen late tonight and Saturday morning as the HRRR shows. Otherwise, just a few clouds and light winds are expected through Saturday. && .FIRE WEATHER... Issued at 350 PM MDT Fri Aug 21 2020 The fire danger will be somewhat elevated on Saturday with the above normal temperatures and low relative humidities. However winds are expected to be weak on Saturday. There will be a very gradual increase in moisture through the week. For Sunday and Monday, isolated storms are expected over the mountains. By midweek, scattered mountain storms are expected, with a chance of storms on the plains. Initially there will be a dry lightning threat. Coverage should be very limited on Sunday, but there could be more dry lightning on Monday and Tuesday. After that the storms will mostly be rain producing. A cold front about Thursday will bring more moisture from the Front Range eastward with some cooling. Strong winds are not expected during the period, though there could be a little increase in ridgetop winds and afternoon upslope breezes as a weak westerly flow aloft develops. A further increase in the westerly flow aloft is likely next weekend, and while this could result in some increase in surface winds, they do not look particularly strong at this time. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Meier SHORT TERM.......RJK LONG TERM........Gimmestad AVIATION...Meier FIRE WEATHER.....RJK/Gimmestad
Area Forecast Discussion
National Weather Service Cheyenne WY
810 PM MDT Fri Aug 21 2020 .UPDATE... Issued at 809 PM MDT Fri Aug 21 2020 Winds have eased and evening humidity is slowly recovering with sunset. Allowed the Red Flag Warning to expire on time at 8 PM as critical fire weather conditions are no longer expected overnight. Updates have been sent. UPDATE Issued at 400 PM MDT Fri Aug 21 2020 Hitting RFW criteria across Carbon County and western Albany County this afternoon. Looks like winds will continue through sunset today. Decided to issue a short fused RFW for FWZs 303 through 308 today. Updates sent. && .SHORT TERM...(This evening through Sunday) Issued at 225 PM MDT Fri Aug 21 2020 GOES-16 GeoColor RGB highlights the large area across the western CONUS engulfed by wildfire smoke from California advecting along the north side of the upper level ridge. Plenty of smoke still looks to be ejecting from their source regions so far this afternoon and staying south of a stationary boundary analyzed from eastern MT through central ID. So far, numerous ASOS sites across the CWA have reported marginal reductions in visibility due to the smoke. Most notably, Laramie and Rawlins are currently sitting at 5 SM. Height increases continue across the region today and Saturday as warmer temperatures and drier weather settles in. An outside chance for showers are possible across the Nebraska Panhandle and extreme southeastern Wyoming associated with increased convergence from a lee side trough. Best chance for any precipitation or thunder will be between 3-6 PM MDT today and any storms that do develop will be short-lived with limited instability and weak shear. With little to no precipitation expected, the main impact heading into the weekend will be widespread smoke across the region. Recent HRRR Smoke forecasts indicate that higher near-surface smoke concentrations will continue to spread southeastward across the CWA through Saturday morning. With the continued west-southwesterly mid-level flow the next few days, expect smoke/haze to continue to fill the skies through the weekend. Went on the cooler side of models for Saturday and Sunday afternoon due to the potential hazy skies, but forecast temperatures remain well above normal in the mid-90s across the NE Panhandle and Wyoming High Plains. .LONG TERM...(Sunday Night - Thursday) Issued at 322 AM MDT Fri Aug 21 2020 No changes to the previous long term/extended forecast with all models still showing a transition from hot and dry to a more unsettled and rainy pattern by mid to late next week. The stubborn upper level high will remain near the Wyoming/Colorado/Utah border through Monday afternoon. The additional midlevel subsidence associated with the upper level high will result in little or no thunderstorm coverage through Monday afternoon. However, can`t rule out a few thunder showers near/in the mountains due to upslope convergence along the Laramie Range. Kept low POP, but did mention of thunder along and west of I-25. Hot temperatures will continue Sunday and Monday with highs around 90 (west), and mid to upper 90s to around 100 degrees further east. Record highs are likely across portions of the area both days. Subtropical moisture and an increase in thunderstorm activity is still expected beginning Tuesday and continuing through middle of next week. Models show Pacific energy finally coming onshore late Monday and Tuesday, which will flatten the upper level ridge axis and nudge the stubborn strong high further south into the southern Colorado/New Mexico/western Texas area. This will allow low to midlevel moisture advection around the western fringe of the upper level high. Kept the trend of increasing chances of thunderstorms (30 to 50 percent) each day through Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 532 PM MDT Fri Aug 21 2020 VFR. Areas of haze with visibility of 6 miles. Wind gusts to 24 knots at Wyoming terminals until 04Z, then gusts to 20 knots at Rawlins after 15Z Saturday. && .FIRE WEATHER... Issued at 225 PM MDT Fri Aug 21 2020 Elevated fire weather conditions currently ongoing across Carbon and Albany Counties with humidities and wind gusts hovering just below critical levels. Warm and dry conditions continue into the weekend. Relative humidities will drop down near critical levels, especially west of the Laramie Range. However, as the upper level ridge continues to build overhead winds will remain relatively light with gusts only around 15 MPH Saturday and Sunday afternoon. Additionally, smoke from wildfires across Colorado and California will continue to advect across the region the next several days. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...GCC SHORT TERM...MB LONG TERM...TJT AVIATION...RUBIN FIRE WEATHER...MB
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
534 PM MDT Fri Aug 21 2020 .AVIATION...00Z TAF CYCLE TSRA confined mainly to area mtns this afternoon, will drift south through the evening with VCTS continuing across KDMN, KTCS. Gusty outflow winds the main concern, with a TEMPO33020G35KT at KDMN. Will be a chance for VCSH/VCTS at KLRU/KELP this evening/early overnight, but current satellite imagery suggests this threat will be small. Another round of TSRA Saturday in the mountains with isolated TSRA/SHRA/gusty outflow spilling into the lowlands by evening, mainly west of the Rio Grande. && .PREV DISCUSSION...315 PM MDT Fri Aug 21 2020... .SYNOPSIS... After another hot day on Saturday, temperatures will cool down a few degrees, but still remain above average. Scattered mountain and isolated lowland thunderstorms will remain possible through Sunday, but a drying trend will commence on Monday. By Tuesday, rain chances will mainly be confined to the Gila Mountains. && .DISCUSSION... .SHORT TERM...This afternoon through Saturday... The subtropical ridge remained centered over northern Arizona this afternoon, with north to northeasterly flow aloft remaining in place across New Mexico. Moisture remains limited. A special 18Z RAOB (intended for testing equipment after the failed 12Z launch) revealed PW of just 0.88 inches... and very strong CIN due to warm air around 700 mb. Low level moisture is lacking as well, especially across the Mesilla Valley, where dewpoints have mixed out into the upper-30s. 50s dewpoints are hanging on in Hidalgo County, leftover from outflow from a strong MCS over Arizona last night. A strong Gulf Surge continues to feed moisture into Arizona from the Gulf of California, with light westerly winds pulling some of this moisture into SW New Mexico. As such, this remains the most favored area for late afternoon and evening thunderstorms, as convection over the higher elevations of the Gila Region drops to the south and southwest. CAMS runs have been flaky, with many of the 12Z HREF members and recent HRRR runs backing off on lowland thunderstorms. 12Z GFS suggests that while 700 mb temps are slightly cooler over SW New Mexico, CIN nevertheless remains fairly strong. Still decided to keep slightly higher PoPs in the Bootheel than most other lowland areas through tonight. CAMS also suggest that after dark, some isolated showers and perhaps a thunderstorm could develop in the lower Mesilla Valley (including around ELP) as outflow convergence occurs. Given the overall poor moisture and strong CIN, this doesn`t seem to deserve much more than a 10-PoP. && 25 .LONG TERM... The UL high over the Four Corners will not move much for the next several days. Through Sunday, some recycled low-caliber monsoonal moisture will continue to rotate around the high from the north, keeping PWAT values near or just below 1.00". This will keep rain chances in the picture with scattered afternoon thunderstorms in the mountains and isolated storms in the evening. With northerly flow in place, a few weak disturbances could give us some enhancement to our convection, but given the sub-par moisture, it wouldn`t be much. Temperatures will at least trend downwards, but remain well above average. On Monday, flow aloft becomes more oriented east-to-west, which will pull in some dry, continental air into the CWA. Enough moisture may hold on for Monday to keep rain chances alive, especially west of the divide, but rain chances drop off by Tuesday as too much dry air enters the forecast area. We may also see some subsidence related to now TD 14 (expected to become Marco) as it moves up the I-35 corridor in TX (keeping east of our CWA), further reducing our storm chances. From Tuesday onwards, storm chances will be mainly across the Gila where better moisture will remain. Everyone else will likely stay dry though an isolated storm cannot be ruled out over the Sacs during this time either. Forecast guidance begins to diverge beyond Wednesday into the weekend. The ECMWF moves the high directly over NM and keeps conditions very dry and very hot. The GFS depicts a much weaker high and even forces a weak inverted trough into our area. Moisture remains scant even in this scenario, but higher than its European counterpart as some of now TS Laura`s moisture gets pulled southwest into the Borderland. Either way, the GFS depicts 0 QPF, but its temperatures are not as hot as the Euro. The 6z run of the GFS too has a weaker high, but instead of letting some of Laura`s moisture get pulled southwest into our forecast area, it forces the inverted trough into the heart of TX as a weak closed low, reinforcing the dry air and subsidence across NM. Given the uncertainties and no real signal to increase precip chances otherwise, I kept the low to nil POPs from the NBM as we head into the weekend with most lowland locations staying dry. && && 25 .FIRE WEATHER... High temperatures will remain around 10 degrees above normal through the weekend, dropping just a few degrees for much of next week. Thunderstorms will mainly be focused on the higher terrain, with below normal coverage, and secondary focus on the lowlands in southwestern New Mexico. Overall thunderstorm chances will be even lower next week. Afternoon minimum RH values will generally be in the 25 to 35 percent range in the higher terrain, and dropping into the 10s across the lowlands. && 25 && .PRELIMINARY POINT TEMPS/POPS... El Paso 75 103 75 101 / 20 0 20 0 Sierra Blanca 70 95 68 95 / 20 20 0 0 Las Cruces 70 101 70 99 / 20 0 20 0 Alamogordo 69 102 71 101 / 10 10 10 10 Cloudcroft 54 78 52 77 / 20 30 20 40 Truth or Consequences 71 100 71 99 / 10 10 20 20 Silver City 64 94 66 93 / 30 40 30 30 Deming 70 102 70 101 / 20 10 30 0 Lordsburg 70 98 70 99 / 30 30 30 10 West El Paso Metro 75 104 77 103 / 20 0 20 0 Dell City 70 102 70 101 / 20 0 10 0 Fort Hancock 74 102 73 102 / 20 10 10 0 Loma Linda 70 95 71 95 / 20 10 10 0 Fabens 75 102 75 101 / 20 0 10 0 Santa Teresa 73 102 73 101 / 20 0 20 0 White Sands HQ 71 101 73 101 / 20 0 20 0 Jornada Range 69 100 71 99 / 20 0 20 0 Hatch 70 101 71 101 / 10 0 20 0 Columbus 73 103 73 101 / 20 10 30 0 Orogrande 71 101 71 101 / 20 0 10 0 Mayhill 59 87 59 87 / 20 20 10 40 Mescalero 58 89 57 87 / 20 30 20 40 Timberon 58 86 57 85 / 20 20 10 30 Winston 59 93 58 92 / 20 30 20 40 Hillsboro 66 100 66 98 / 20 20 20 20 Spaceport 69 100 69 99 / 10 0 20 10 Lake Roberts 58 94 58 93 / 20 40 30 40 Hurley 65 96 65 96 / 40 30 30 20 Cliff 65 99 64 98 / 40 40 30 30 Mule Creek 65 95 66 95 / 40 40 30 40 Faywood 66 97 67 96 / 30 30 30 20 Animas 69 99 68 101 / 30 30 40 0 Hachita 68 98 67 100 / 20 20 40 0 Antelope Wells 68 97 67 98 / 30 30 50 0 Cloverdale 65 92 66 93 / 30 30 40 10 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...None. TX...Heat Advisory until 9 PM MDT this evening for TXZ418-419-423-424. && $$ 99/99/99
National Weather Service Hastings NE
658 PM CDT Fri Aug 21 2020 .SHORT TERM...(This evening through Saturday) Issued at 252 PM CDT Fri Aug 21 2020 Still a rather quiet forecast, but with a few interesting changes to note (mainly regarding tonight). There has been a bit of back and forth regarding the possibility of precip tonight. A couple days ago models started picking up on a possible short wave with an associated weak sfc boundary. This feature was generating some QPF signals for portions of the area for this evening/tonight. Even last night several of the hi-res models still showed this as a possibility, but this morning`s 12Z runs have changed course and gone completely dry for this evening/tonight. While this could very well end up being the case...there are a few additional considerations that make me hesitate. For starters there is the recent history of nightly convection...5 out of the last 7 nights actually. There is also the fact that we are not expecting much of a pattern change aloft. However, even with that all being said, I ultimately decided to err on the drier side for tonight (though not 100% dry). Tomorrow looks to be more of the same (as tends to be the case with very little pattern change). Highs will be above average in the lower to mid 90s. .LONG TERM...(Saturday night through Friday) Issued at 252 PM CDT Fri Aug 21 2020 No significant changes have been made to the long term as there is relatively very little pattern change aloft. This means we will continue to remain in north and northwesterly flow aloft (till about Mon) and the primary concern is the potential for ridge runners. After Monday models are indicating that the eastern trof becomes significantly less amplified. This will lead to the ridge spreading out broadly over the majority of the CONUS, and rather zonal flow over the northern CONUS. This would also subsequently push the jet stream further north and effectively cut us off from the main flow...effectively leading to rather static conditions for several days. This week highs are expected to be above average for late August, in the 90s, and dry. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday) Issued at 650 PM CDT Fri Aug 21 2020 Significant wx: None. Tonight: VFR. Will see a temp incr in high clds this eve, otherwise should be mostly clr. Smoke from fires across W CONUS has noticeably increased this aftn and will continue into overnight. Don`t have vsby restrictions attm as it is pretty high based. Winds will be SSE-S less than 10kt. Confidence: High. Saturday: VFR. Will probably see even more smoke Sat per HRRR smoke model. Will have to watch vsby trends to the W, but don`t think it`ll be thick/low enough to include in TAFs attm. Just know vsby may not be perfect/10sm. Actual cld cover looks pretty limited until perhaps mid to late aftn when a few tstms may dev. Confidence on coverage/timing to low to include this far out. Winds will be SE- SW at less than 10kt. Confidence: Medium && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Shawkey LONG TERM...Shawkey AVIATION...Thies
Area Forecast Discussion
National Weather Service Elko NV
225 PM PDT Fri Aug 21 2020 .SYNOPSIS...Areas of smoke and haze continue to affect most of northern and central NV today, and likely linger through the weekend as large fires continue to burn in California. Thunderstorms return to some areas on Sunday, and likely spread to most of northern and central NV Monday and Tuesday. Temperatures start to cool down after the weekend, but theyll remain above average. && SHORT TERM...Today through Sunday. Dry and mostly storm-free conditions are expected across all zones through Saturday with the exception of a stray isolated high-based dry thunderstorm over White Pine county late tomorrow afternoon. Model guidance is consistent with the idea that as more moisture streams north into central and northeastern Nevada with a predominate southerly upper flow, the risk for isolated thunderstorms will become an increasing concern by Sunday and continue into next week. Isolated dry thunderstorms should dominate the northern forecast zones as a mix of wet/dry storms prevail over White Pine and northern Nye counties. Dense layers of smoke advecting into northern Nevada from the large fires burning in California will likely lead to reduced visibilities at times through tomorrow along with reduced air quality over the region. HRRR model guidance shows a general pooling of dense smoke layers over northern Nevada through at least Saturday morning. Heat risk factors could still be a concern going into Sunday as daytime highs remain well above normal touching the high 90s over some locations. Near record setting high temperatures are forecasted for the Elko area on Sunday. .LONG TERM...Sunday night through Friday. Model agreement is consistent on the upper level ridge shifting to settled over the Four Corners region producing southerly flow. However, the handling of the remnants of Tropical Storm Genevieve and the short waves associated with it are a little less consistent. GFS has a stronger eastward push of the remnants than the ECMWF. Instability is still expected throughout the beginning of the period, with possible dry thunderstorms moving to include showers as moisture builds over the week. Monday and Tuesday have the best potential for showers and thunderstorms across the region, while Tuesday afternoon also presents concerns for fire weather conditions in south-central Nevada. However, confidence remains low for fire weather and accumulation amounts for locations are still uncertain. Temperatures continue to stay above average, but should cool down a bit into the upper 80s and 90s as the week progresses. && AVIATION...Smoke from California and western Nevada fires will continue to blanket most of the state. KWMC and KBAM will likely be the most impacted with visibilities dropping as low as 1 SM during the period. && FIRE WEATHER...Drier and more stable air will continue across the region through Saturday with a slight risk of isolated dry thunderstorm activity over White Pine county. A moderately moist monsoonal airmass will spread north into central NV through Saturday evening and continue to influence thunderstorm development into early next week. The expected combination of weak instability over portions of central and possibly northern NV by Sunday afternoon will result in a mix of isolated wet and dry thunderstorms. Any storms that do develop on Sunday will likely lean toward the dry side over the northern fire zones. As the northward push of monsoonal moistens central and northern NV through Monday, a transition to mostly wet thunderstorm should occur. && CLIMATE...Well above normal temperatures persist through the weekend, with high temperatures running 10 to 15 degrees above normal. Slightly cooler early next week with high temperatures generally 7 to 10 degrees above normal. && .LKN WATCHES/WARNINGS/ADVISORIES... Dense Smoke Advisory until 9 AM PDT Saturday for Humboldt County- Northeastern Nye County-Northern Elko County-Northern Lander County and Northern Eureka County-Northwestern Nye County-Ruby Mountains and East Humboldt Range-South Central Elko County- Southeastern Elko County-Southern Lander County and Southern Eureka County-Southwest Elko County-White Pine County. && $$ 97/94/86/97
Area Forecast Discussion
National Weather Service Lubbock TX
911 PM CDT Fri Aug 21 2020 .UPDATE... Have updated forecast to reflect a decrease in precipitaion chances area wide. The southeastern Rolling Plains may still see a few isolated weak thunderstorms, but in general drier continental air has begun to enter the area limiting storm coverage. && .PREV DISCUSSION... /issued 609 PM CDT Fri Aug 21 2020/ AVIATION... VFR will likely continue for all TAF sites for the next 24 hours. Isolated to scattered thunderstorms will be possible this evening and overnight but coverage and timing is too low to mention in the TAF. PREV DISCUSSION... /issued 200 PM CDT Fri Aug 21 2020/ SHORT TERM... Small PoP chances will manifest themselves this evening and overnight into early Saturday morning. An upper ridge will remain anchored over Arizona tonight with the center of the ridge shifting to the 4-corners on Saturday. For today, a weak surface trough was oriented from the northwestern Texas Panhandle into southeastern New Mexico which is where isolated to scattered convection is expected to develop. A minor speed max at 250mb will punch down into the area this evening from the north. Although this looks to exclusively boost the large scale lift in the Rolling Plains which will be under the left exit region of this jet. Additionally, a short wave was seen on water vapor imagery moving south across the Texas Panhandle this afternoon. The RAP model was even showing a small amount of positive PVU advection with this short wave confirming its existence. Higher levels of low-level theta-e exist within the surface trough and will result in increased instability. A notable drop off in instability will occur outside of the surface trough axis with the smallest values across the Rolling Plains. Any storms that do make it into the FA this evening and overnight do not have a high chance of producing severe wind gusts. Precipitation chances will be lower on Saturday with a drier layer of air moving overhead at the mid levels of the atmosphere. LONG TERM... Currently, the upper-level ridge remains to the west over the southwestern CONUS, and a trough is currently over the southeastern CONUS. In the long-term, models seem to be split on how they want to handle the trough to the east and tropical cyclone #14 located southeast of the Yucatan peninsula. A majority of the models want to stretch the trough to the southwest, creating a closed low near southeastern Texas. The upper high will build to the northeast into Canada. This amplification in the upper-level ridge will shift the flow aloft more northeasterly by late Saturday, advecting drier air into the mid-levels. The low will most likely open, becoming an inverted trough, and move to the southwest early in the week. By mid to late Tuesday, tropical cyclone #14 will make landfall, most likely on the east coast of Texas. Models are currently weakening the tropical cyclone as it makes landfall and advecting the latent heat and vorticity into the inverted trough over south Texas. The PVA and addition of the latent heat will amplify the inverted trough which may cause it to close off again. The closed low will move north towards the Texas Panhandle Wednesday, shifting the winds aloft more easterly and then back to the north-northeast as it slides east of the area. We should remain on the subsidence side of the low, keeping precipitation chances to the east. By the end of next week, the low near the area will move off to the northeast, and a trough over British Columbia will dig to the south. This will shift the high over the western CONUS east towards the forecast area, shifting the winds more northerly aloft. With the upper high remaining near the area, expect mostly dry conditions and above normal temperatures next week. Kendrick && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 28/28
Area Forecast Discussion
National Weather Service Midland/Odessa TX
637 PM CDT Fri Aug 21 2020 .DISCUSSION... See 00z aviation discussion below. && .AVIATION... VFR conditions are expected for the next 24 hours. Winds will generally be out of the southeast to east but may become northerly tonight with a chance of SHRA. && .PREV DISCUSSION... /issued 245 PM CDT Fri Aug 21 2020/ DISCUSSION... Persistence rules. WV imagery shows the upper ridge has not moved much over the past 24 hours, and is still centered over ern AZ, maintaining meridional flow over West Texas and Southeast New Mexico. Of immediate concern is a shortwave over south central KS that will move down the ern periphery of the ridge this afternoon and tonight. For the past few days, models have brought this feature thru the ern zones, especially the SREF yesterday, and the GFS today. However, the 12Z GFS appears to have the shortwave too far west than what WV imagery shows The HRRR solution looks more representative, in which case convection from this disturbance will stay east of the CWA altogether. That said, models do hint at developing convection in NE NM this afternoon, as they have the past couple of days, and bringing it south into SE NM. In addition, once the cap erodes, the Davis Mtns look to develop convection, as well. The ridge is still forecast to move up to the Four Corners by 00Z Sun, where it will remain the rest of the weekend. Models advertise plenty of perturbations moving south into the area Sat/Sun, for general isolated convective activity, mainly over SE NM and areas east. Next week, the ridge is forecast to link up w/its counterpart over the SE CONUS, but the two tropical systems set to invade the Gulf coast states look to keep this from happening, and keep the ridge roughly over the Four Corners area. Much will depend on the evolution of two tropical systems, but for now, grids look pretty dry after Sunday. Regarding temperatures, temps still look to drop below triple digits for most areas after today, and bottom out in the mid 90s for most of West Texas and Southeast New Mexico Mon afternoon. However, w/the two tropical systems keeping the ridge over the Four Corners, thicknesses begin increasing Tue thru the extended, and temps most locations could very well be back in the triple digits by next weekend. For now, most areas should stay at or below the century mark. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 72 98 71 98 / 10 10 10 10 Carlsbad 71 99 71 100 / 20 0 10 10 Dryden 74 100 71 98 / 10 10 0 10 Fort Stockton 72 99 71 97 / 10 0 0 10 Guadalupe Pass 68 92 69 91 / 30 10 0 20 Hobbs 69 97 69 96 / 20 0 10 20 Marfa 64 94 61 92 / 30 20 10 10 Midland Intl Airport 72 99 71 98 / 10 10 10 10 Odessa 73 99 71 99 / 10 0 10 10 Wink 74 102 72 101 / 20 0 10 10 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...Heat Advisory until 8 PM MDT this evening for Guadalupe Mountains of Eddy County. TX...Heat Advisory until 9 PM CDT /8 PM MDT/ this evening for Central Brewster County-Chinati Mountains-Chisos Basin-Davis Mountains-Davis Mountains Foothills-Guadalupe and Delaware Mountains-Lower Brewster County-Marfa Plateau. && $$ 99/99/99
Area Forecast Discussion
National Weather Service Marquette MI
652 PM EDT Fri Aug 21 2020 .SHORT TERM...(This evening through Saturday) Issued at 652 PM EDT FRI AUG 21 2020 Water vapor imagery and RAP analysis show wnw flow today across the Great Lakes btwn troffing over se Canada and ridging over the Rockies. Within this flow, a shortwave trof is noted from southern Saskatchewan to the Dakotas with another shortwave over northern Ontario btwn Lake Superior and James Bay. Otherwise, there are no apparent shortwaves immediately upstream. Fog/low clouds were slow to lift/break up today from the Keweenaw se into the eastern U.P. To the sw, it`s been a partly to mostly sunny, warm/humid day with temps rising into the lower 80s and dwpts in the 60s. The differential heating boundary btwn the areas that cleared out early today and the areas that have seen more clouds resulted in shra/tsra developing around 18z from Ontonagon County e to the sw half of Marquette County. With MLCAPE around 2000j/kg and around 30kt of deep layer shear, several storms have been well organized and have produce large hail/damaging winds. As has been the case over the last couple of days, forecasting when/where convection will occur tonight/Sat will be a challenge. At least in the near term, shra/tsra will continue to expand along the differential heating boundary over the next few hrs. Outflow boundaries and advancing lake breezes will provide additional low- level forcing. There will continue to be a svr risk with these storms. Any of the storms will be capable of producing torrential rainfall. What happens later this evening/overnight already becomes more uncertain. Although approaching shortwave trof should support an increasing low-level jet during the night, guidance does not show anything more than 20-25kt at the higher end, but that may be sufficient to develop some convection thru the night across the fcst area. With weakening shortwave trof moving across the area on Sat, shra/tsra will be possible at any time during the day. However, will probably end up with fog/stratus developing tonight, so that would lead to the better potential of shra/tsra in the later aftn. In addition, lake breeze will again push inland, providing a low-level focus in the aftn hrs. .LONG TERM...(Saturday night through Friday) Issued at 357 PM EDT FRI AUG 21 2020 Long term pattern over the United States will continue to feature upper-level ridging over southwestern CONUS that extends northward into the Rocky Mountains and at times, into the northern Plains. Initially in the period, Bermuda High over the western Atlantic will allow the flow pattern over the Upper Great Lakes to flatten out following the exit of Saturday into Sunday`s frontal passage. As this high over the Atlantic shifts south early next week, long-wave troughing will briefly establish itself over eastern North America by midweek, ushering in another period of NW flow over the forecast area. Beyond this, there are some discrepancies in the amplitude and duration of the following ridge and subsequent timing of the next shortwave trough over the region. Overall, this pattern looks to usher in a few opportunities of showers due to embedded shortwaves within the NW flow and near normal to above normal temps with the potential for a brief cool period. Beginning Saturday night into Sunday, frontal boundary over the region with continued theta-e advection will keep showers possible overnight into early Sunday. The west and central could see a break in the precip begin overnight into Sunday morning, as the main forcings shift eastward. As instability increases during the afternoon, another round of scattered showers and thunderstorms look possible in the west and central. In the east, expect the outgoing shortwave to keep showers in the area overnight Saturday into early Sunday, with the possibility of a break by mid-morning. I`m less certain about this given the guidance spread. Regardless of this break in the east, guidance is consistent with afternoon showers and thunderstorms. Temps on Sunday should largely mirror Saturday`s given the persistent airmass over the region. Another shortwave may move into the region Monday afternoon into the evening, but models vary on the evolution and location of the better forcing. Ridging will extend into the Northern Plains as surface high builds eastward over Ontario on Tuesday. This looks to be the best shot of a dry day over the region, but a shower or storm can`t be ruled out, mainly west and south. As upper level troughing digs into the northeast, models vary on the southern and western extent of the cooler temps. The 12z GFS is now trending more in line with the Canadian and Euro with this evolution, and temps in the low- mid 70s by the lakeshores and upper 70s is expected inland. Beyond Tuesday, the next better shot for precip looks to be on Wednesday afternoon or evening into Thursday, but guidance varies on the timing and location of this feature. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 628 PM EDT FRI AUG 21 2020 Stalled frontal boundary over the area will support sct shra/tsra at times across Upper MI thru Sat. This will make a challenging forecast based on the fact that the models do not handle convective pcpn very well, so confidence with this forecast is low. Expect low clouds/fog to redevelop tonight, leading to MVFR conditions at KIWD and IFR to LIFR at KCMX/KSAW. Conditions later Sat afternoon will be VFR at all sites. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 652 PM EDT FRI AUG 21 2020 Weak pres gradient will prevail across the area for the next several days. As a result, expect winds mostly under 20kt. With a more humid air mass over the area and with some showers and storms moving across the lake at times, some fog patches are expected. The fog could be locally dense. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Dense Fog Advisory until 8 PM EDT /7 PM CDT/ this evening for LSZ162-240-263. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...JP AVIATION...07 MARINE...Rolfson
Area Forecast Discussion
National Weather Service San Francisco Bay Area
840 PM PDT Fri Aug 21 2020 .SYNOPSIS...Marine layer returns tonight. Winds weaken and back towards the west to southwest through tomorrow. All eyes then on the arrival of potential elevated thunderstorms late in the weekend through early next week. A fire weather watch has been issued as a result of these potential thunderstorms. && of 08:39 PM PDT Friday...Thin high clouds have been rolling into the Central Coast and parts of interior San Benito County this evening. These are associated with post- tropical cyclone Genevieve, whose moisture has been advecting into SoCal this evening while also increasing instability in that area. Please refer to the previous discussion for a more in- depth analysis for this weekend`s setup, as the entrainment of its moisture is progged to come in the form of pulses through the weekend and into the early part of next week. As for tonight, the LNU lightning complex is 15 percent contained as of 8pm, while other fires in the region, including the SCU lightning complex, are also around the same ballpark. Please refer to CALFIRE for the latest on the containment of all the active incidents in the region. Smoke is expected to continue blanketing most of the Central Coast, East and North Bays, and the interior, with slightly better conditions over the SF Peninsula. Recoveries from last night`s marine layer played a large part in helping firefighting efforts along the coast and in lower-elevation locations across the CWA. The Fort Ord Profiler has steadily approached 1000 ft while the 00Z sounding at OAK showed a similar depth for the Bay Area. As such, looking for a marine layer depth similar to what was observed last night in the 1000-1200 ft range, which will help greatly in tomorrow`s humidity recoveries. Higher terrain locations immediately above the ceiling will Unfortunately not receive the same moisture benefits but winds have been trending towards being lighter than what`s been observed this week, which is good news for those locations. && .PREV of 02:00 PM PDT Friday...The Bay Area remains situated between a 550dm H5 trough centered over the Gulf of Alaska to the northwest and a 594dm H5 ridge to the southeast. The ridge influence waned yesterday as the trough nudged slightly moreso over the region, bringing cooler, moister air to the area from the northwest and allowing the marine layer to deepen to approximately 800-1200 feet (depending on location) last night into this morning. This marine layer brought much improved overnight humidity recoveries to fires burning in coastal counties except the higher ridges and even helped ease the extremely dry conditions for the LNU complex and River/Carmel fires farther inland by bringing fair recoveries there as well. The two fires that received the least aid were the SCU complex due to it being deeper inland and well above the marine layer and the Dolan Fire along the Big Sur coast, similarly due to the higher terrain there above the marine layer. As we`ve previously discussed, some of the warmest/driest conditions during the overnight period exist just above the marine layer, in this case appeared to be roughly 1500 feet and above. The marine layer also made some pushes inland, pushing into the Sonoma, Napa, Salinas valleys and forming an "otter eddy" in the Monterey Bay that eventually drove moister air into Santa Cruz and up high way 17/9s in the Santa Cruz mountains under light southeast flow this morning. So far today, the atmosphere is warmer and more humid when compared to the same time yesterday. Temperatures are roughly 2 to 6 degrees warmer (as a lobe of the high pressure nudges westward) while humidity values are 5 to 20% higher (due to lingering impacts of the marine layer push and trough to the northwest). While today should mostly play out similarly to yesterday through the afternoon, there will be some subtle changes as we move into the early evening and overnight period as a lobe of monsoonal ridge air advects westward over the region. Due to the ridge rebuilding in from the east later today, winds will begin to show minor shifts, particularly late in the afternoon to evening, shifts from predominately NW-WNW inland towards W to WSW (aka backing winds), though due to our complex terrain there will be many other minor variations. Winds are forecast to weaken and shift increasingly more towards the WSW to SW across the broader area on Saturday, which should be a net positive for fire fighting efforts but could add some notable fire behavior complications due to shift in wind directions driving fire movement (primarily more E to ENE or even NE), though it is important to note-- at a much slower pace due to the lower wind speed expected. The marine layer is expected to redevelop along the coast again late today and behave similar to last nights 1000 foot marine layer. That said, some notable marine layer difference tonight include that it will a) favor more WNW to W flow, b) show some signs of suppression from the expanding ridge from the east, c) expanding ridge may intensify the warm/dry air mass presence linger just above the marine layer. Finally, a fire weather watch has been issued for the entire San Francisco Bay Area and Central coast from 11am Sunday through 11am Tuesday. This is due to the remnants of former Hurricane (and current Tropical Storm) Genevieve moving northward during this time frame and merging with some ambient monsoonal moisture/instability while being enhanced by a deepening trough off the coast. Medium term models that better resolve convection show strong indications that intermittent periods of elevated convection will occur as this tropical moisture merges with subtropical forcing. At this time, there are three time periods we are watching closely. The first is actually not covered by the fire weather watch as that watch is issued primarily for long duration fire events and may distract from the second/third pulses that will be considered the "main" event. However, we should not gloss over it. So, an initial weak push of elevated instability and moisture will move into the region from north to south, primarily along the immediate coast and potentially into the North Bay Saturday PM into Sunday AM. The tropical fuel with this initial surge looks somewhat limited versus the second and third surges, and will have little to no upper level support from the adjacent trough. Expect to see some altocumulus clouds at a minimum with the potential for a few isolated thunderstorms developing in this timeframe, mainly just off the coast but potentially just inland. Again, not to distract from the main period of concern, this potential event is outside the fire weather watch, but should be watched closely in case future forecast model runs look more inviting during this time frame. Confidence continues to increase that the ingredients will begin to come together during the time frame of the fire weather watch, or midday Sunday through midday Tuesday. There are two time periods we are watching closely during this extent, however, just the first of these two was sufficient in issuing the fire weather watch, during the late Sunday into early Monday time frame. We are also watching, though with much less confidence, a second potential surge of elevated moisture/instability in the late Monday to early Tuesday time frame as the last of the offshore moisture/instability moves over the region. That said, this set up does not look as extreme as the recent historic event that brought thousands of lightning strikes and numerous fires to the region. The "fuel" with this upcoming event looks similar to the last event, however the "engine" that will dictate the performance of the "fuel" is not as impressive. It is important to note however that with our recent historic lightning event that we did not see the true magnitude of the impact until it was only 24 to 36 hours out, which is not unusual given the poor data off the coast and difficulties the resolving the break down of a hurricane, and it is entirely possible that the forecast will trend towards a stronger event. Even if so, there are some key difference between the upcoming event and the previous event. These differences include that the high pressure system to the east will be weaker, meaning lower temperatures, higher humidities, less marine layer suppression (though some will exist), and finally much less monsoonal moisture/instability merging into the remnant tropical moisture that we saw with the last event. Additionally, numerous wildfires with a history of extreme growth are already present on the ground and the bigger factor from these thunderstorms may not even be the potential for dry lightning, but instead the potential for erratic gusty outflow winds ahead and with the thunderstorms and weaker breezy inflow winds in the wake of the thunderstorms. Erratic gusty winds are extremely difficult to manage on fire lines. These erratic gusty winds are typically only associated with the strongest thunderstorms in our region which are extremely rare however last weekends event shows it can indeed occur here. A reminder, that last cluster of strong thunderstorms which prompted an extremely rare severe thunderstorm warning for the region was issued due to these winds, of which brought peak gusts in the 50-75mph range, especially over the higher and favorable terrain where many of these wildfires are burning strongest at this time. Current thinking is that the fire weather watch will remain the active product through the next 24 hours, with high likelihood of moving towards a more concentrated Red Flag Warning after Saturday mornings fire weather conference calls and the arrival of the latest forecast data from the 12Z runs. This situation will continue to rapidly evolve, especially over the next 24-48 hours, so please keep an eye on the weather conditions and latest updates from us, your local CALFIRE unit (North Bay is LNU, East/South Bay is SCU, San Mateo/Santa Cruz is CZU, Central Coast is BEU), local city/county, county emergency managers, and sheriffs departments for the latest information available for your local area regarding the current ongoing wildfires and any necessary evacuations. Looking beyond the lightning, the forecast remains complicated. The aforementioned low pressure trough off the coast is expected to transition from offshore to along the coast and just inland just beyond any burst of elevated convection, potentially promoting a period of breezy to gusty onshore WSW to SW winds. Otherwise, smoke will continue to impact the region to varying degrees as long as the fires are burning, so be sure to follow updates on spare the air days from the regional air quality districts or from the latest HRRR smoke output shared by our office on social media. && .AVIATION....As of 5:58 PM PDT Friday...for 00z TAFs...A widespread influx of higher humidity /water vapor/ has occurred per higher dew point temperatures in the upper 50s to lower 60s per metar surface observations at the airports. This influx is ahead of a very weak cool front approx 100 miles NW of the coastal North Bay; the front is seen as an isolated thin cloud band on visible satellite. Coastal stratus is otherwise mixing with wildfire smoke, the marine layer depth is near 1,000 feet. Wildfire smoke continues to produce poor slant range and surface visibilities /LIFR-IFR/ otherwise it`s VFR- MVFR. Cirrus clouds far in advance of post tropical cyclone Genevieve will move up from the south tonight and Saturday. The 00z TAFs carry previous idea that wildfire smoke will mix with a stratus push overnight; chilly sea surface temps 51 to 56 per buoy data interacting with dew point temps at or above current sea surface temps resulting in additional spontaneous saturation to stratus/fog within the marine layer tonight and Saturday morning. Late night and early morning air mass stability again causing poorest conditions with VLIFR to IFR. Model forecasts hint that a slow, steady intrusion of cooler air arrives Saturday afternoon and night. This influx combining with diurnal mixing should lift stratus/fog and may help a little with lifting wildfire smoke, not from a deepening marine layer rather an influx of fresh sea breezes. Vicinity of KSFO...VFR, west wind to 30 to 35 knots until mid evening. May need to issue an airport weather warning for winds if sustained or gusts continue longer at the terminal. Forecast is IFR ceiling forming by 12z Saturday morning with a return clearing by 17z. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...Poor slant range and surface visibilities due to NW wind advecting wildfire smoke downwind over the Monterey Bay from the CZU August Lightning Complex. Expect VLIFR-IFR ceilings and visibilities tonight and Saturday morning, improving somewhat during the day due to diurnal surface warming and mixing and fresher afternoon sea breezes undercutting wildfire smoke with a cooler air intrusion from the northwest; similar improvement may continue into Saturday evening just beyond the current 00z taf cycle. && of 4:53 PM PDT Friday...Moderate to locally gusty northwest winds will continue across the coastal waters through Saturday night. Winds will then begin to diminish on Sunday as high pressure over the eastern Pacific weakens. Remnants of Tropical Storm Genevieve will bring a chance of thunderstorms on Sunday and potentially into early next week. Increased long period southerly swell is possible over the outer waters through this weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 AM SCA...Pigeon Pt to Pt Pinos 0-10 nm until 3 AM GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Mry Bay until 9 PM && $$ PUBLIC FORECAST: Diaz/AS/DRP AVIATION: Canepa MARINE: W Pi Visit us at Follow us on Facebook, Twitter, and YouTube at:
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 250 PM CDT Fri Aug 21 2020 The main concern in the short term is the chance for thunderstorms tonight into Saturday, then attention will turn toward temperature forecasts through the mid part of next week. Large scale mid tropospheric pattern is similar to yesterday, with a ridge extending from AZ up into Alberta and Saskatchewan. A trough stretches from MI down to the western part of the Gulf of Mexico. There was a weak closed low in the trough near the border of MS and AL. Water vapor imagery early this afternoon showed a shortwave trough moving across southern Canada and the Dakotas. The tail end of this wave extended down into north central NE. A few showers were noted in south central SD with that feature. Surface analysis at 2 pm had a weak trough from eastern ND down into western NE. Temperatures in eastern NE and western IA were in the upper 80s and lower 90s with dewpoints in the mid and upper 60s and southerly winds. Tonight into Saturday night... The majority of the convection allowing models (CAMs) including the HRRR, ESRL HRRR and RAP13 suggest the early evening hours will be dry in our area. There is a fairly decent signal later tonight and Saturday morning with some of the other CAMs that isolated to widely scattered thunderstorms could occur mainly from west central IA back into northeast NE. For now, will hold POPs at 20 percent or less in the forecast area, generally north of Omaha and Lincoln. Lows tonight should be in the 60s. Spotty storms could linger until late morning Saturday, then we expect the rest of the day to be dry. Temperatures should peak in the upper 80s and lower 90s. It appears another weak shortwave may move in from the northwest for Saturday night in some of the model guidance, especially the GFS. There could also be some lift from a weak low level jet. Will keep some low POPs for southwest IA and far southeast NE. Sunday through Wednesday evening.... This period is expected to be mainly dry. The 500 mb ridge to our west will expand into the central US, with heights increasing to 591 decameters or more. With the mid level warming, we should be mostly capped with precipitation chances dropping to less than 15 percent. High temperatures through this period should be mostly in the lower and mid 90s, with some upper 90s possible mainly Monday and Tuesday. Lows should be in the 60s to lower 70s. Heat index values could reach near 100 each day for a few hours. Late Wednesday night into Friday and next weekend... There is fairly good model agreement that the ridge will start to flatten by Thursday, with the flow across the central US becoming more zonal by late week and then turning toward the southwest. This would be a more favorable pattern for precipitation in our area, especially at night. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 648 PM CDT Fri Aug 21 2020 For the most part, VFR conditions should prevail across the region through Saturday. This will include FEW-SCT clouds between 5,000 and 15,000 ft AGL and unrestricted visibility. We will be watching for a few stray thunderstorms between 05Z Saturday and 00Z Sunday, with the best storm potential between 21Z Saturday and 00Z Sunday. Any of the TAF sites (KOMA, KOFK or KLNK) may be affected by a stray storm, but those impacts should be brief. For the time being confidence is to low to include any mention of thunderstorms in the TAFs. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Miller AVIATION...Albright
Area Forecast Discussion
National Weather Service Nashville TN
921 PM CDT Fri Aug 21 2020 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Upper low continues to spin over the region late this evening, and moisture remains deep. While a weak SFC boundary remains well south, there is an H85 boundary over the mid-state, and along with this upper low, will provide sufficient vertical motion to keep showers and isolated storms going most of the night. The heavier showers/clusters are likely to continue slow northwest movement, and have adjusted pops to reflect this trend. Overall the threat for flooding or strong/severe storms very low rest of the night. Temps need no adjustment at this time. && .AVIATION... 00Z TAF DISCUSSION. BNA/MQY/CKV/CSV...An upper low is circulating to our south, with widespread showers and a few storms occurring across Middle Tennessee as a result. The HRRR suggests that some shower activity will continue overnight, but the primary risk to aviation will be radiation fog and possible low stratus, mainly after midnight and lasting into the early morning tomorrow. Expect conditions to improve after 12Z, but look for thunderstorms across the mid state Saturday afternoon. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......07 AVIATION........08
Area Forecast Discussion
National Weather Service San Diego CA
123 PM PDT Fri Aug 21 2020 .SYNOPSIS... Hot weather will continue today, except at the coast and in the higher elevations. Temperatures will cool a bit this weekend before slowly warming up next week. Scattered thunderstorms are forecast to develop over the mountains each afternoon through Monday. Mostly dry weather is anticipated Tuesday through the remainder of the week as the upper ridge axis slides just south of the International Border. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Latest GOES satellite at 1 PM shows thin high clouds streaming in from the south from Tropical Storm Genevieve. Showers and thunderstorms were beginning to develop over the mountains, and will continue throughout the afternoon. The potential exists for a few showers, and perhaps a thunderstorm or two, developing west of the mountains this afternoon. The latest 19Z HRRR has backed off a bit from this morning on development west of the mountains this afternoon. Confidence is rather low, but the potential is there. Another hot day is in store for inland areas, especially the Inland Empire and the High Desert, where an Excessive Heat Warning continues through this evening. The lower deserts, San Diego Valleys and Inland Orange County will be a few degrees cooler today compared to yesterday, but with the humidity, it will continue to feel hot and muggy out there. Increased moisture from Tropical Storm Genevieve and sufficient instability will result in scattered thunderstorm activity over the mountains this afternoon and again Saturday afternoon. Moisture and instability look similar between today and Saturday, with PWs around 1.1" to 1.3" over the mountains, and CAPE values over 1000 J/kg. Given similar moisture and instability, there should be similar activity on Saturday as today, mainly concentrated over the mountains. Moisture largely moves out of the region on Sunday, so thunderstorm chances decrease, although some isolated convection over the mountains is not out of the question on Sunday afternoon and Monday afternoon. Over the weekend, cooler temperatures are in store for inland areas as the strong high pressure further weakens. Temperatures will be near to slightly below seasonal normals for Saturday and Sunday. Temperatures will warm up slightly on Monday as the high pressure begins to strengthen again. The high pressure becomes more northeast to southwest oriented on Tuesday, and will continue to strengthen throughout the week. As the upper ridge axis becomes positioned across the International Border, this will effectively shut off the monsoonal flow for the middle to end of next week. Temperatures will gradually warm-up throughout the week as the high strengthens. At this time, the warm up is not looking as significant as we saw this week, but still about 5 to 7 degrees above normal for most areas. && .AVIATION... 212000Z...Coast/Valleys...Expect stratus with bases of 1000-1500 ft MSL to develop late tonight near the coast. Expect prevailing SCT conditions, but may see periods of BKN ceilings 13-17Z Saturday at KSAN/KCRQ/KSNA. The potential exists for isolated SHRA over the coast/valleys through Saturday, mainly during the afternoon hours. Confidence is too low on timing/coverage to mention in the TAFs. Mountains/Deserts...SCT TSRA persist through 00Z with bases near 10,000 ft MSL and tops to 40,000 ft. Strong, gusty and erratic winds and lightning will occur in vcnty of TSRA. The activity will dissipate 00-02Z. Development can be expected again Saturday afternoon 18-00Z, with scattered coverage over the mountains expected. Otherwise, unrestricted vis prevailing through the period with mainly high clouds. && .MARINE... No hazardous marine conditions are expected through Tuesday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 10 PM PDT this evening for Apple and Lucerne Valleys-San Bernardino and Riverside County Valleys-The Inland Empire. PZ...NONE. && $$ PUBLIC...Connolly AVIATION/MARINE...Moreland