Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/11/20

Area Forecast Discussion
National Weather Service La Crosse WI
1049 PM CDT Mon Aug 10 2020 .SHORT TERM...(This evening through Tuesday) Issued at 213 PM CDT Mon Aug 10 2020 Latest 19z surface analysis shows cold front extending from southern Ontario Canada into southern Iowa. Latest mosaic radar imagery indicates mesoscale complex along surface front with showers north of main complex of convection over southern forecast area. Surface ridge over the Northern Plains states will build into the Great Lakes Region tonight and Tuesday. This will provide dry weather across the forecast area. Stronger winds aloft are expected to inhibit any widespread fog development in the Mississippi River and some of the tributaries. Temperatures tonight will drop into the upper 40s to 50s and highs are expected to climb into the upper 70s to middle 80s Tuesday. .LONG TERM...(Tuesday night through Monday) Issued at 213 PM CDT Mon Aug 10 2020 The 10.12z GFS/NAM/ECMWF are in good agreement in developing west to east zonal flow aloft Wednesday into Thursday. The combination of pieces of energy in the flow and southerly moisture return will produce on and off small shower and storm chances across much of the forecast area. Main focus of convection will be west of the forecast area...where better vertical motion and moisture convergence is located. High temperatures Wednesday into Thursday will be near seasonal with highs mainly in the lower to middle 80s. Main forecast concerns Friday through Monday are precipitation chances through much of the period. The 10.12z GFS/ECMWF/GEM show differences with overall flow pattern through the period. Main differences is how amplified upper level ridge will be over the eastern United States and the strength of the upper level trough over the Northern Plains states. This will have impacts on timing of the small convection chances Friday into Sunday across the forecast area. Depending on timing...subsidence underneath shortwave ridge will allow for dry weather Monday. Temperatures Friday and Saturday will be the warmest out ahead of the upper level the 10.12z GFS/ECMWF indicate 925mb warming to plus 20 to plus 23 degrees celsius. High temperatures will be well in the 80s. Cooler air advects into the forecast area behind upper level trough Sunday and Monday with highs cooling into the 70s. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1049 PM CDT Mon Aug 10 2020 Look for this to be a quiet period with VFR conditions. An area of high pressure over southeast South Dakota late this evening will drift slowly east and be over northern Illinois by Tuesday evening. This will keep skies relatively cloud free with light west to southwest winds. Not expecting any valley fog to form and impact KLSE tonight as both the 11.00Z NAM and 11.02Z RAP shows winds of 10+ knots from about 1000 feet and up for much of the night that should create too much mixing just above the surface to allow fog to form. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...DTJ LONG TERM...DTJ AVIATION...04
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
848 PM EDT Mon Aug 10 2020 .UPDATE... Quick update this evening for the timing of showers and storms. Enough instability with ML CAPEs of 1500 to 2000 J/Kg with the MCV moving through central Lower to have categorical POPs for the western part of the CWA but with the weakening trend only have likely POPs for the eastern part. Severe threat is waining also with little shear and decreasing instability with the loss of diurnal heating. && .PREV DISCUSSION... Issued at 704 PM EDT Mon Aug 10 2020 AVIATION... Potent squall line crossing Lake MI will impact the TAFs sites just after 02z based on current forward speed and propagation. Hi-res runs continue to suggest that the storms will be weakening quite a bit as they get into southeast MI. While wind fields are much weaker over the region, there is still enough instability with the convective vort over Lake Michigan that the storms should hold together but will likely be sub-severe. Hi-res runs also continue to hold onto additional development with ahead of the cold front after the evening convection...around 05z for MBS to as late at 11z for the Detroit area. In the wake of the convection, expect a period of MVFR cigs and vsbys into Tuesday morning. Eventually, the cold front will pass through the forecast area with much drier air for Tuesday late morning and beyond. For DTW...Specific timing for DTW would place the storms arrival between 0210z to 0235z. While severe wind gust not likely, potential for a 30 to 35 kt gust. Much greater uncertainty with the second batch of thunderstorms after 06z. DTW THRESHOLD PROBABILITIES... * Medium for ceiling at or below 5000 ft from 02z through 15z. * High for thunderstorms from 02z to 04z and medium from 06z to 12z. PREV DISCUSSION... Issued at 356 PM EDT Mon Aug 10 2020 DISCUSSION... A warm and muggy day remains underway as temperatures sit firmly in the upper 80s with dew points holding in the lower 70s with with only a minimal cumulus response as seasonably warm h700 temperatures hold between 9-10C. For the remainder of the afternoon... Increasing build up of moisture ahead of an approaching cold front, still just west of Lake Michigan, will gradually increase precipitation chances across central Michigan this afternoon as near full solar insolation has allowed for rapid destabilization of the atmosphere. Aforementioned lower-level cap and lack of synoptic support will hold precipitation chances at just a chance through the afternoon and early evening, with any development mode being pulse in nature and short-lived as deep layer bulk shear values remain weak, to or just below 20 knots. Regardless, with MLCAPEs rising around 2,000 J/kg across Flint into the Tri-Cities (1,500 J/kg for locations south) this afternoon, any pre-frontal pulse thunderstorms will be capable of producing heavy downpours and wet microbursts. Attention then turns to an upstream MCS complex now just entering northern Indiana which has had a history of producing damaging wind gusts across Iowa. Latest 16Z HRRR (and support from 1000-500 MB thickness) continues to advertise an ESE prorogation of the storm system which has it clipping southwest Michigan by 00Z before taking a more southeasterly trajectory following the better CAPE gradient down into the Ohio Valley. However, have noted that the forward propagation of the current system is faster than that displayed in the HRRR model runs (no surprise given strong RIJ), which could clip Michigan sooner than expected, capitalizing on better instability. Integrity of the system could still hold and clip southern Michigan given the sufficient mid-level lapse rates between 6-7C and instability in place, but maximum bulk shear values will continue to be a limiting factor. This ongoing system bears watching as we head into the evening, mainly 23Z onwards, and would be primarily a wind threat, where damaging winds will be possible. Additionally, strong fgen along an advancing cold front/upper level shortwave will bring additional chances for thunderstorm development for the remaining areas of the cwa, with similar thermodynamic and kinematic variables in place this evening. Slight uptick in bulk shear values to 25 knots ahead of the front (slight uptick in mid-level wind speeds) and cooler mid-levels will help support more organized convection, but timing of thunderstorm development (~00Z-05Z) will be met with waning instability, and would promote a weakening trend from west to east. Overall, all of SE MI remains in marginal/slight risk for severe weather tonight per SPC mainly for wind gusts concerns, where gusts around 60 mph will be possible with stronger storms. Otherwise, heavy downpours leading to localized flooding concerns and lightning will be the primary threats with thunderstorm development. Severe weather threat will quickly wane after Midnight. Post-frontal dry air will quickly fill in behind the cold front with lingering rain showers early overnight. Residual moisture axis in conjunction with diurnal heating could produce some weak showers early Tuesday afternoon, but a building high pressure system will fill in behind the front and will produce dry weather through at least the midweek period. Zonal flow/little change to thermal profile will support temperatures in the mid-80s through the week with dew points in the upper-50s to lower 60s. Better chances for rain and thunderstorm returns through the weekend as a warm front edges north into the region. MARINE... Light southwesterly winds will continue to bring warm and humid conditions into the central Great Lakes for the remainder of the afternoon, while a cold front moves in later this evening bringing the chance for showers and thunderstorms. Strong to severe thunderstorms are possible with strong wind gusts, frequent lightning, and erratic waves being the primary marine threats. Wind gusts are expected to remain at or below around 20 knots with the passage of the cold front, although higher gusts are possible with thunderstorm activity. The passage of the front causes a shift to northwesterly flow, also allowing showers and thunderstorms to diminish during the early morning hours. High pressure then begins to build overhead, with light winds and dry conditions persisting through the middle of the week. HYDROLOGY... Warm and humid air is firmly in place over SE Mi today as a cold front approaches from the Plains and Midwest. Clusters of thunderstorms are expected to develop west during the afternoon and move into the region with the front tonight. Rainfall totals average a quarter to a half inch in this pattern with locally higher amounts to or in excess of one inch will be possible with any thunderstorm development. Heavy rain threat will end around or slightly after Midnight. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ UPDATE.......RBP AVIATION.....RBP DISCUSSION...SF MARINE.......MV HYDROLOGY....SF You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Hanford CA
102 PM PDT Mon Aug 10 2020 .SYNOPSIS...Scattered afternoon thunderstorms over the Sierra Nevada mainly north of Tulare County are possible through Tuesday. Normal to above normal afternoon highs will continue across the valley for the next week. && .DISCUSSION... Seasonably hot weather to continue across the San Joaquin Valley today as many areas are forecast to surpass the century mark by afternoon. High temperatures are forecast to be in the 98-103 degree range for most of the valley today. Latest GOES17 imagery is depicting some building CU over the Sierra Nevada, mainly north of Tulare County. HRRR model guidance is showing thunderstorms developing around 2 PM; these thunderstorms will be capable of gusty winds 40-50 mph, small hail, and localized downpours. High temperatures will moderate a couple degrees tomorrow as upper troughing begins to influence the area. Afternoon convection over the Sierra Nevada again look possible, mainly north of Tulare County as instability prevails. The trough will usher in drier air aloft by Wednesday and this will likely halt the chance for convection as dew points are forecast to be 10-12 degrees lower than on Tuesday. High temperatures to remain near normal through Wednesday and Thursday as the upper trough slowly advances over the area. Some moisture from Tropical Storm Elida may pivot around a desert southwest ridge by Thursday and Friday, which could bring some cloud cover over Central California these days. By this weekend, a strong upper ridge will shift west over Central California, heralding the return of widespread triple digit heat. Afternoon highs by Saturday will range from 100-105 degrees across the SJ Valley, and up to 104-109 degrees in Indian Wells Canyon. && .AVIATION... Isolated thunderstorms can be expected near the Sierra crest through 03z Tuesday. Otherwise, VFR conditions will prevail over the central California interior during the next 24 hours. && .AIR QUALITY ISSUES... On Monday August 10 2020... Unhealthy for sensitive groups in Kern County and Sequoia National Park and Forest. Further information is available at && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is high. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && $$ public...Bollenbacher aviation....Bollenbacher
Area Forecast Discussion
National Weather Service Lincoln IL
815 PM CDT Mon Aug 10 2020 .SYNOPSIS... Issued at 253 PM CDT Mon Aug 10 2020 Scattered thunderstorms will affect the area into tonight. Some of the storms could be severe into this evening, with damaging wind gusts being the main threat. Locally heavy rain will also be possible. The front will push into southern Illinois for Tuesday and Wednesday, with scattered storms more dominant over the southern half of the state. Temperatures will cool a bit for the next few days, with more seasonable readings through midweek. && .UPDATE... Issued at 815 PM CDT Mon Aug 10 2020 Main gust front has pushed south of our forecast area limiting potential for severe winds. Plan on hanging on to SVR 428 a bit longer south of I-70 given proximity of the extrmely unstable air to our south and the nearby warnings being issued by WFO PAH. Otherwise, 3km NAM and lates HRRR CAMs are trying to keep chances for thunderstorms in place over central and southeast Ilinois into the early morning hours. This seems reasonable given the depiction of the triggering shortwave still lingering over central Iowa nd Southwest MO. Will make some adjustments to lower PoPs in the northwest but will retain at least chance in the central and southeast through the night. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 253 PM CDT Mon Aug 10 2020 Greatest severe weather threat at least over the next couple of hours will be across the northern CWA, mainly I-74 north as the squall line tracks east. Widespread 60+ mph gusts with tree and power line damage have been reported across Knox and Stark counties as of 230 pm. This area will shift east over McLean Co. through 4 pm. Progressing south of I-74 this line of storms becomes more outflow dominant, posing a lower severe threat over the short term. Upstream we are seeing another batch of severe storms developing over northeast MO. CAMs have had varying solutions with this activity, but the general feeling is this will develop east along the front/outflow from initial squall line, and pose an additional severe threat over the central/southern CWA later this afternoon and into the evening. Though deep layer shear remains rather weak under 25 kt, very high instability (surface based sampled at 5400 J/kg on 18z ILX sounding) will lead to a continued damaging wind gust potential into this evening. Steep mid level lapse rates will also pose a secondary hail threat, mitigated by high wet bulb zero heights. We expect the main severe threat to diminish over out southeast counties around 9-10 pm. A lesser but still notable concern over the next few hours is high heat and humidity as 80F dewpoints have pooled ahead of the storm complex. This has pushed heat indices around 105F in many locations. This will continue through around 6 pm in areas that remain storm-free. Later tonight and Tuesday, the front will shift into southern IL. This is where chance pops will be confined, with drier weather expected over the northern half of the CWA into Tuesday night. .LONG TERM...(Tuesday night through Monday) ISSUED AT 253 PM CDT Mon Aug 10 2020 Few changes made to the extended due to ongoing severe weather. The front will remain in the general area Wed-Sat, though notable dry periods are likely, especially over the northern half of the area. This will keep seasonably warm weather in place through Saturday. While there is some uncertainty in timing an more significant cold front is progged late Saturday or early Sunday. This would result in cooler/drier weather for the end of the weekend and into early next week. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 605 PM CDT Mon Aug 10 2020 Rain with isolated embedded thunderstorms will persist for the next couple hours, diminishing from the west. A brief reduction to MVFR ceiling/vis possible in a heavier shower/storm, but chances are too low to include in the TAFs. After the rain exits this evening VFR skies with mid to high level clouds into Tuesday afternoon. Any lingering gusty winds in showers will diminish over the next couple hours, then winds will remain under 10 kt through tomorrow afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barker SYNOPSIS...25 SHORT TERM...25 LONG TERM...25 AVIATION...25
Area Forecast Discussion
National Weather Service Marquette MI
741 PM EDT Mon Aug 10 2020 .SHORT TERM...(This evening through Tuesday) Issued at 432 PM EDT MON AUG 10 2020 Water vapor imagery and RAP analysis show a mid-level low over northern Manitoba with broad trof extending s into the Northern Plains/Upper Mississippi Valley. Fairly well-defined shortwave that has lifted from the eastern Dakotas to just n of Lake Superior has provided some assistance to convection that has been developing along and ahead of sfc cold front which currently runs from eastern Lake Superior across central Upper MI. Per SPC mesoanalysis, air mass ahead of the front is characterized by MLCAPE upwards of 2000- 2500j/kg with deep layer shear of 30-35kt. Thus, storms have been well-organized at times, posing a svr risk. Behind the cold front, dwpts are falling off quickly from the excessive values ahead of the front in the upper 60s/lwr 70s F. KIWD and KLNL are already down to around 50F. Farther w, dwpts this aftn across the Dakotas are well down into the 30s and lower 40s F, a sign of the drying that will continue into Tue. Ongoing convection (and its associated svr risk) ahead of cold front will continue to push s and e over the next few hrs, clearing the fcst area by 00z. Much drier air as already alluded to above will stream into the area during the night, resulting in skies becoming clear. Given the dry column, leaned fcst toward some of the cooler guidance for min temps. 50s will generally be the rule, but around 60F near Lake Superior and probably dipping into the upper 40s in the typically cooler areas in the interior. Expect abundant sunshine on Tue under a dry air mass. Given the low dwpts present upstream across the Dakotas and into western MN, incorporated some of the mix down potential to lower dwpts beyond all guidance. Although dwpts will be comfortably low, down into the 40s F for most of the fcst area, it will be a warm day as midday 850mb temps will be around 14/15C. Highs should generally be in the mid 80s with some upper 80s where w to wsw winds are a downsloping wind direction. Will be a little cooler where those winds are onshore from the Great Lakes. Deep mixing in the dry air mass will support breezy conditions. Fcst soundings suggest gusts of 20-30mph during the day, strongest over the nw half of the fcst area. Although it will be warm and breezy with RH down as low around 25pct in the aftn, recent rainfall will ease fire wx concerns. .LONG TERM...(Tuesday night through Monday) Issued at 335 PM EDT MON AUG 10 2020 Not much has changed for the forecast through the extended. It will remain on the warm side throughout the week with temperature remaining around 10 degrees above normal for this time of year. While the warmth will persist, the humidity levels will drop significantly through at least Wednesday as an anomalously dry airmass moves into the region. The weather looks to remain dry and warm through mid-week as high pressure lifts northeast across the area and up into Canada by late week. Medium range guidance diverges quite a bit through the end of the week when it comes to thunderstorm chances. This is not a surprise given the strong surface ridging moving through the region and a blocking high/ridge over the Southwest slowing the progressive nature of the upper-air pattern across the CONUS. Thus, not going be confident on precipitation chances until late week/weekend. However, once we get to the end of the week and through the upcoming weekend, the weather should become more active as longwave troughing tracks east across the Upper Great Lakes and a few embedded shortwaves rotate through the area. By early next week it does look like we will see a cool down, back towards near-normal temperatures as the above mentioned longwave trough digs southeast of the area and northwest flow prevails. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 739 PM EDT MON AUG 10 2020 Clear skies and drier air over the region will keep VFR conditions at all three TAF sites this forecast. Main concern is gusty winds developing tomorrow with daytime mixing, with gusts to around 20 knots until late afternoon expected at all three sites. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 432 PM EDT MON AUG 10 2020 In the wake of a cold front clearing Lake Superior late this aftn, wsw winds will gust up to 20-25kt across the west half of Lake Superior tonight. Winds will be slightly lighter over the east half. Winds will increase some on Tue under tightening pres gradient btwn low pres over Hudson Bay and high pres shifting e toward the southern Great Lakes. Expect gusts into the 20-30kt range across the w half of Lake Superior on Tue, strongest off the w side of the Keweenaw Peninsula. Wind gusts should be mainly under 20kt over much of the e half. High pres ridging will then dominate thru the midweek period, keeping winds under 20kt. Winds should increase a bit during the late week period as the high pres ridge shifts east. Gusts may reach 25kt at times over mainly the e half of Lake Superior. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...TAP AVIATION...RJT MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
338 PM CDT Mon Aug 10 2020 .UPDATE... Issued at 338 PM CDT Mon Aug 10 2020 Update to the aviation section. Going to discuss the overall faster trends in the models. The latest HRRR seems more in line with reality. If it pans out, we could see activity into our SEMO, southwest IL counties by 6 or 7 p.m., and then along a line from Evansville to near Paducah by 10 or 11 p.m. && .SHORT TERM...(Tonight through Tuesday night) Issued at 234 PM CDT Mon Aug 10 2020 Easily verified the Heat Advisory across most of the area with around 105F values, actually 105-110F over southern IL. We will continue with the headline for heat through 7 p.m. Isolated convection formed over the KY Pennyrile along a boundary. The rest of the area is quiet for now. Attention is on severe convection over NW IL back into northern and west MO. This activity is running faster than most all of the CAMs guidance. It`s also more prominent over Missouri (CAMs lacking). The convection is focused along a boundary and driven by a mid level wave. We project the activity will get into our area late today, or this evening. Timing is still a bit of a tough call. But as of right now if trends continue, the CAM`s and deterministic solutions are likely too slow. Expect additional adjustments to timing between now and midnight. Severe is certainly a concern given the high degree of instability, favorable mid level drier air, decent lapse rates and overall momentum. Highest chance area is from parts of southeast MO into southern IL and southwest IN. Chances lower overnight with any southward progress. What will determine Tuesday`s PoPs are how prominent and expansive the convection is tonight. The airmass could get worked over. Or if the activity weakens enough, and sets up a zone of instability and convergence over southern sections, we could see renewed convection. We lowered Pops overall given the possibility of the former happening. There will be another chance of showers and thunderstorms Tuesday night. We will take another look as highs on Tuesday. We may be a bit too warm with the current forecast. .LONG TERM...(Wednesday through Monday) Issued at 234 PM CDT Mon Aug 10 2020 Plenty of moisture will remain across the middle Mississippi and lower Ohio valleys the rest of the week. Models show an upper level trof over our region through the week. At the surface, a cold front will meander across our region through Friday. This will continue to give us chances of showers and thunderstorms Wednesday through Friday, with the best chances during the late morning and afternoon hours. Models lift the front north of our area by Saturday, and push the upper trof just east of our region. However, with moisture still in place, weak impulses in the mid/upper level northwest flow will keep chances for isolated to scattered convection in the forecast through the weekend. Best chances will continue to be diurnally driven, with lower chances during the overnight. This pattern will continue into Monday, though we could see temperatures and dew points finally trending down a little. High temperatures will generally be in the 86 to 91 degree range Wednesday through Friday, then a couple of degrees warmer over the weekend. Monday might only be in the lower to middle 80s. Lows through the extended will be in the upper 60s to lower 70s. Daytime dew points will be in the lower to middle 70s, dropping a few degrees for the overnight hours. && .AVIATION... Issued at 338 PM CDT Mon Aug 10 2020 Strong to severe convection from central IL into central MO is moving to the east, southeast faster than previously forecast, and has expanded in coverage. We now project that by 03-05z, the leading edge of the storms should be from about KEVV to KPAH. Strong and gusty winds may accompany this complex of storms, along with MVFR/IFR conditions in very heavy rain. It appears the activity will let up after midnight, with variable light winds developing and a return to VFR conditions, that should last through Tuesday morning. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Heat Advisory until 7 PM CDT this evening for ILZ075>078-080>094. MO...Heat Advisory until 7 PM CDT this evening for MOZ076-086-087-100- 107>112-114. IN...Heat Advisory until 7 PM CDT this evening for INZ081-082-085>088. KY...Heat Advisory until 7 PM CDT this evening for KYZ001>022. && $$ UPDATE...08 SHORT TERM...08 LONG TERM...RST AVIATION...08
Area Forecast Discussion
National Weather Service Pocatello ID
202 PM MDT Mon Aug 10 2020 .SHORT TERM...Tonight through Wednesday night. General trend is for dry weather and breezy afternoon conditions through the short term period. Fire weather products have been issued to address this. Isolated thunderstorms are possible Tuesday and Wednesday mainly in the southern highlands and eastern highlands. Above normal daytime temperatures will continue through Wednesday but will be a bit cooler on Wednesday. Expecting low elevations highs in the low 90s Tuesday and upper 80s Wednesday. Wind gusts in the Snake Plain generally in the 20 to 30 mph range Tuesday and Wednesday extending north into the highlands as well. GK .LONG TERM...Thursday through Monday. Expecting dry and hot conditions in the long term period as an upper ridge builds overhead by next weekend. Temperatures will be slightly above normal Thursday through Saturday with highs expected to reach the mid to upper 90s by Sunday in low elevations. May still be breezy Thursday and Friday but winds should decrease through the weekend as the upper ridge builds overhead. GK && .AVIATION... Gorgeous wx for aviation will continue for yet another day across SE Idaho, with mostly clear/VFR skies and no LLWS concerns. Breezy afternoon winds have been the main (and really only) element of any consequence, and speeds look slightly weaker today across MOS/HRRR guidance compared to what we saw over the weekend, with trajectories lining up well with most of the major runways. Overall forecast confidence is high. KSUN may yet again see a shift from SE to SW this afternoon, and while the signal is weaker compared to the weekend, we have included it in the TAF. Timing should run a bit behind yesterday...perhaps 21z (3 PM), producing a slight crosswind at the terminal. Winds veer further into the west just off the sfc. Several of the HREF ensemble members, with support from the latest HRRR/RAP, do hint at an isolated t-storm developing near the ID/UT border south of KBYI, and in the Central Mntns near Challis/Mackay NE into srn MT after 21-22z (3-4 PM), and while this should not impact our TAF terminals, did throw a few clouds into KSUN to account for some nearby cumulus development in the terrain. We also continue to monitor smoke production from the Phillips Creek Fire for possible advection east toward KSUN, but sfc obs, webcams, and DEQ air quality stations continue to suggest this has not been a major problem, and the HRRR smoke model doesn`t throw any red flags for today, so suspect KSUN will remain unaffected. Looking to Tue, a trough is forecast to push inland across the PacNW, increasing our SW flow (esp for the Snake Plain terminals) and potentially working a few t-storms into the srn highlands. Early projections suggest this activity should stay south of KBYI and KPIH, but it may be close. Breeziest conditions should affect KPIH and KIDA. - KSmith && .FIRE WEATHER... Dry wx continues with no significant relief in sight. After extensive coordination with SPC, GBCC, fire dispatch centers, and surrounding offices, we have upgraded the FIRE WEATHER WATCH to a RED FLAG WARNING from 1-9 PM Tues for Zones 476 (ern Central Mntns), 425 (ern Magic Valley), and 410 (Snake Plain). RHs are a slam dunk, with winds the weak link, barely brushing low-end criteria for most areas with low confidence even after blending in an 80-90% composite of the normally breezier/more accurate MAV/MET guidance for the Snake Plain. A key decision here was: Is the case stronger for upgrading to a warning, or canceling the watch and having no alerts out due to the marginal winds? Given a forecast Haines Index of 6, RH values as low as 8-11%, and winds just a few kts short, we felt an upgrade was more appropriate. We also wanted to make a decision today to give fire partners some lead-time on the warning, instead of waiting until full coordination would be possible again late Tue AM. There is still the potential for an isolated t-storm to sneak NE from NV into Zone 427 (Cassia County) or even wrn 413 Tue eve, but a review of our first full round of high-res reflectivity guidance suggests any activity will likely remain isolated, with better potential south of the border. CWR is near zero given the dry low- level airmass. Winds/RH are also too marginal for 427 to include them in the Red Flag. Wed we flip-flop...widespread critical winds appear likely across every zone (except perhaps 427), but RHs are in question (should increase with some moisture working up from the south). Best overlap of critical winds/RH exists over wrn 410, so we issued a FIRE WEATHER WATCH here from 1-9 PM Wed. If RHs were to trend lower, additional zones may need to be considered. Overnight RH recovery is mediocre at upper slopes Tue night (struggling to reach 40%) as also noted by crews on fires in BOI`s area, but all-in- all didn`t see a strong meteorological reason to run a Red Flag right through the entire 2 days as our neighboring MSO/TFX offices are doing in MT. Finally, t-storms remain possible Wed afternoon/eve across the ern/srn highlands, but a first look at the NAMNest suggests isolated coverage, so confidence is very much not there for triggering a Red Flag based on lightning at this time. The PacNW trough will stay with us Thurs with a chance of critical winds/RH overlapping at least for Zones 410/476, but with headlines already out for 2 days, did not want to issue for Thurs and potentially cause confusion. A weak cold front may cross the region Thurs eve. This weekend appears to feature a building ridge of high pressure with hotter temps. - KSmith && .PIH WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 1 PM to 9 PM MDT Tuesday for IDZ410-425- 476. Fire Weather Watch from Wednesday afternoon through Wednesday evening for IDZ410. && $$
Area Forecast Discussion
National Weather Service Riverton WY
435 PM MDT Mon Aug 10 2020 .SHORT TERM...(This evening through Tuesday night) Issued at 130 PM MDT Mon Aug 10 2020 Totally clear skies early this morning have given way to building cumulus early this afternoon, particularly on the north side of the Uintas and northward toward Big Piney and Pinedale. Expecting more cumulus to build over the Wind Rivers and Absarokas and move eastward during the late afternoon and early evening. Continues to be very isolated chances of thunderstorms over these areas for the rest of the day, and the HRRR is also indicating the Wind River Basin into Natrona County early this evening due to slightly higher surface moisture and weak low-level shear. Thus, the storms should not be very strong and the bigger hazard would be from dry lightning. Breezy and dry conditions continue across southern WY for elevated fire weather conditions this afternoon and early evening as well. Skies will be mostly clear overnight with some clouds across the northern mountains and possibly southern WY. Tuesday will see more clear skies across much of northern WY as dry windy conditions move in from eastern Idaho. Some mid-level moisture will slowly stream from northern Utah across southern WY as the mid-level flow becomes more west-southwest. As a weak leeside surface trough develops over eastern WY, winds will increase Tuesday afternoon with 700mb flow increasing to 20-30 knots and the height gradient tightening. Have continued the forecast with a slight chance of showers and thunderstorms from southwest WY ENE toward Natrona County and across Sweetwater County. Dry lightning will certainly be a concern Tuesday afternoon. Thus, a red flag warning is in effect from much of the forecast area for lower afternoon humidities and stronger winds. A weak shortwave trough from Nevada will move northeastward Tuesday night into Wednesday morning toward western WY. The western areas will see clouds increase early Wednesday morning with a slight chance of showers around sunrise over the far western mountains. Afternoon temperatures continue to be near of just above normal for early August, with the drier overnight air .LONG TERM...(Wednesday through Monday) Issued at 150 PM MDT Mon Aug 10 2020 Not much change over the past 24 hours in the expected evolution of the overall synoptic pattern. Shortwave and mid-level moisture will progress across western Wyoming Wednesday in southwest flow aloft ahead of broad trough over western Canada. Wednesday afternoon and evening will likely provide the best chance for showers and thunderstorms during the medium-range period. The broad Canadian trough tracks across the northern Rockies Thursday and Friday. Northern stream jet axis will remain to our north both days. This will largely keep any chance of convection limited to locations near the Montana border. However, there is a southern stream jet of 70+ knots that will cross the south Thursday. This will only add to the fire weather concern for Thursday. While the jet energy will subside across the south Friday, wind speeds will still pose a problem as the trough swings to our north. Fire weather highlights are quite possible both days, the question will be the areal extent. Blended models have increased wind speeds for Thursday and Friday to come more in line with what is most probable, so only made minor adjustments. Speeds of 20 to 30 mph still appear to be on-track for many areas. A cold front is still expected to slip into the north Friday afternoon, which will limit fire weather concerns over the Bighorn Basin and Johnson County. The weekend and Monday will be trending warmer with less wind in the forecast. The northern Rockies trough and associated jet will lift into central Canada Saturday. This leaves Wyoming in general westerly flow aloft with a relaxed pressure gradient. Therefore, fire concerns will diminish for the weekend. A ridge over the Desert Southwest and Great Basin then takes hold effectively shutting off any potential for moisture to make its way north. 598dm high will also crank up the heat with 700 temperatures of 16-20C by Monday. Ridge axis will remain to our west or along our western border. Models do hint at some very low pops in the northwest Monday afternoon, but moisture looks very limited. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday) Issued at 430 PM MDT Mon Aug 10 2020 Isolated convection will dissipate with the setting sun around 02Z- 03Z/Tuesday. Gusty westerly wind across southwest Wyoming will decrease to less than 10kts just prior to sunset. Terminals will be VFR through 00Z/Wednesday. Gusty westerly wind anticipated to develop at most terminals between 18Z-20Z/Tuesday Speeds of 15-25kts will be common. && .FIRE WEATHER... Issued AT 150 PM MDT Mon Aug 10 2020 Elevated fire weather conditions continue this afternoon and early evening across southwest into south-central WY due to very warm, dry, and breezy conditions. Isolated thunderstorms are possible over Sweetwater County this afternoon, and then from eastern Fremont into Natrona early this evening. With the very dry boundary layer, there is a chance again of dry lightning out of any storms. Skies will clear overnight and winds should decrease. Skies will be mostly clear to partly cloudy Tuesday, with wind increasing after noon and becoming stronger than Monday. More isolated thunderstorms are possible from Uinta/southern Lincoln counties eastward toward the central mountain areas. Very dry air and stronger wind will move over the western mountains as well. A red flag warning is in effect from noon to 8 pm Tuesday for the critical fire weather conditions. Wednesday will see a disturbance move into western WY early in the morning and bring some weak showers and possible dry lightning to northwest WY. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from noon to 8 PM MDT Tuesday for WYZ277>281- 283-285-287>289-300-414>416. Red Flag Warning from 2 PM to 8 PM MDT Tuesday for WYZ276-282. && $$ SHORT TERM...McDonald LONG TERM...Jones AVIATION...Jones FIRE WEATHER...McDonald
National Weather Service Charleston WV
936 PM EDT Mon Aug 10 2020 .SYNOPSIS... Weather disturbances bring a chance of storms to portions of the area tonight and Tuesday. Cold front arrives Tuesday night, becoming stationary to provide shower/thunderstorm through the end of the week. && .NEAR TERM /THROUGH TUESDAY/... As of 925 PM Monday... Meso-alpha-scale convective system currently moving across western Ohio is showing signs of gradual weakening. 00z analysis indicates a significantly drier atmospheric profile across the RLX CWA than what exists across western Ohio, along with an increasingly stable airmass. Thus, the ongoing convection should continue to weaken through the late evening hours as it begins to encounter unfavorable sustainability factors. However, the far western CWA may have just enough moisture depth and instability to allow for a brief strong storm to occur with the approaching line. As such, SPC has outlined portions of SE OH and far NE KY under a Marginal Risk of severe weather for the overnight hours. But again, this should not be a significant severe weather event for our area. Owing to the placement of the convection as of 01z, I have re- drawn the POPs for tonight to account for a possible scraping of the western and southwestern CWA from the line of storms...especially as the steering flow aloft begins to shift the overall system more towards the southeast. Elsewhere, a rogue isolated shower/storm could develop overnight as various ripples in the H5 flow advect across. Slightly greater convective chances will exist during the day Tuesday as stronger H5 s/w disturbances advect east, but have capped POPs at 30% for Tuesday...mainly due to a rather warm thermal profile and still some questionable moisture depth values. As of 451 PM Monday... Made some significant changes part of the Near Term forecast period. Reduced POPs significantly for the remainder of this afternoon and into the evening hours. A very dry atmospheric profile exists across all but the far western CWA this afternoon. Thus, any convection that tries to develop through sunset should be very isolated, and mainly across NE KY (and possibly far SW VA). Focus for later tonight then turns to ongoing large bow echo currently moving east across Illinois. This complex is prog to move into Indiana over the next hour and begin to shift move southeasterly. During the evening, this complex should gradually weaken as it begins to encounter a drier and increasingly stable airmass. At this time, severe weather is not expected across our CWA tonight, and the majority of the expected remnant convection is likely to be confined to the far western CWA. As such, I have lowered inherited POPs for tonight and Tuesday morning across the board by about 20%. Will likely make further significant changes to POPs for tonight with the evening update...once better convective trends and 00z surface and upper air analysis takes place. As of 215 PM Monday... The surface high pressure, responsible for dry weather during the last couple of days, will weaken even further by Tuesday. This will allow for upper level disturbances to initiate convection from abundant low level moisture in the boundary layer. Models show differences in their solutions especially tonight. The RUC and NAM suggest a possible MCV dropping from the northwest overnight tonight. In other hand NMB and GFS/ECMWF models brings a dry quiet night. Decided to introduce some PoPs across the area to account for this possibility. Any precipitation activity should wane down before sunrise Tuesday morning, but showers and storms are expected during the afternoon and evening hours as additional upper shortwaves cross the area. Temperatures will remain above average through the period. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 209 PM Monday... Surface high pressure will build into the Great Lakes Tuesday night into Wednesday, bringing drier air across much of the northern Ohio Valley, particularly areas north of Interstate-70 where dewpoints mainly in the 50s to near 60 will exist. However, our area will remain too far south of this feature to benefit from this drier air as dewpoints are expected to be in the upper 60s to low 70s across the region. In addition, a stalled frontal boundary across our area will combine with shortwave energy aloft to produce a risk of scattered showers and storms Wednesday afternoon and evening. The frontal boundary will then remained stalled across the middle Ohio Valley into Thursday, with additional chances for scattered showers and storms continuing across the region. With models showing PWAT values as high as 2 inches Wednesday and Thursday, locally heavy rainfall is possible with any of the convection that develops. While dry antecedent conditions will limit a threat for widespread flooding concerns, can`t completely rule out localized high water issues as these storms will be very slow moving. Otherwise, weak shear and poor mid level lapse rates should generally keep severe weather threat on the lower side through mid week. In addition, high temperatures for Wednesday and Thursday will be in the upper 80s to low 90s across the lowlands and 70s for the higher elevations. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 209 PM Monday... The aforementioned frontal boundary will continue to linger in the vicinity of the middle Ohio Valley late week and to start the weekend. This feature will continue to support daily chances for showers and storms Friday and Saturday amid the warm and humid airmass and mid level impulses aloft. By Sunday an upper level trough is expected to drop into the Great Lakes region, which should help the frontal boundary finally lift out of the area. By early next week, models show a strong upper ridge amplifying across the western US and broad troughing across the Great Lakes and Ohio Valley. This should result in slightly cooler air with temperatures slowly trending towards more normal values by the end of the long term period. This feature should also help maintain some chances of showers and storms across the region with conditions remaining unsettled at times through early next week. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... As of 714 PM Monday... VFR expected for much of the TAF period, although some areas of river valley fog overnight may lead to IFR conditions. Dissipating Cu field is ongoing as of writing with some patches of mid/upper level cloudiness drifting across at times. Well to the northwest, a severe line of convection across Indiana is prog to move southeast across Ohio this evening, and eventually shift more southerly. Most of our region should remain just to the east of any of the more substantial convection (which should weaken throughout the evening). KHTS may be just close enough to require a period of VCSH (TS possible) later this evening/overnight. Elsewhere, convective blow off should negate greater fog development. Exception may be KEKN where fog may develop before thicker cloud cover spreads across. VFR expected to prevail Tuesday with a Cu field developing during the day. Iso to widely sct convection may try to develop across the region, but coverage is currently expected to be too sparse to include in TAFs this far out in time. Weak/vrb sfc winds this evening eventually becoming more SWrly around 5 kts. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Slight chance convective complex currently over Indiana tracks a little farther east tonight, which would bring greater precip chances to the area. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE TUE 08/11/20 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H H H H H H H L HTS CONSISTENCY H H H H H H H H M L L H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H L L L M M M PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z WEDNESDAY... No widespread IFR conditions expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...ARJ/RG NEAR TERM...RH/ARJ SHORT TERM...RG LONG TERM...RG AVIATION...RH
Area Forecast Discussion
National Weather Service Tulsa OK
925 PM CDT Mon Aug 10 2020 ...UPDATE... .DISCUSSION... Convection across northeast OK and parts of west central AR continues to slowly weaken, although keeping an eye on the ongoing strong storms over western OK. CAMs output continues to struggle with the evolution overnight, with the recent HRRR suggesting that storms will slowly move into the region later tonight continue to fester across eastern OK Tuesday morning. Main update to overnight forecast is to extend PoPs a bit farther south after midnight. && .PRELIMINARY POINT TEMPS/POPS... TUL 76 94 74 95 / 30 30 20 20 FSM 75 94 73 96 / 20 40 20 20 MLC 77 94 74 95 / 10 30 10 10 BVO 74 92 72 93 / 40 30 20 20 FYV 72 89 70 92 / 20 40 20 30 BYV 71 92 70 93 / 30 50 30 40 MKO 75 92 73 93 / 20 30 20 20 MIO 73 92 71 93 / 40 30 20 30 F10 76 92 73 94 / 20 30 10 10 HHW 77 97 75 97 / 10 20 10 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...18