Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/11/21

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
805 PM CDT Tue Aug 10 2021 .UPDATE... Issued at 804 PM CDT Tue Aug 10 2021 Overall the forecast is in good shape. However, did add a low pop to the northern CWA as frontal boundary slides through overnight. Last few runs of the HRRR have been consistent it cranking out a few showers. && .SHORT TERM...(This Evening through Wednesday Night) Issued at 150 PM CDT Tue Aug 10 2021 Forecast challenges include the ongoing Red Flag Warning as well as temperatures Wednesday. Currently, sunny or mostly sunny skies prevail this afternoon. There is a blanket of thin sct/bkn cirrus streaming into the region from the northwest. Temperatures are warming through the 80s this afternoon. Some locations across central and north central South Dakota will likely top out in the low to mid 90s this afternoon. Breezy west-southwesterly mixing layer winds are helping to drag a rather dry airmass into central and north central South Dakota as well, causing relative humidity values to fall below 20 percent. In fact, relative humidity values will likely be ranging between 20 and 30 percent as far east as the James River valley and the Prairie Coteau in northeast South Dakota by the end of peak heating today. The Red Flag Warning remains in effect until 8 PM CDT this evening. There are a couple of cold fronts sweeping southeast through the region in the short term period. The first front moves through tonight. This should be a dry cold fropa. Some of the latest hi-res CAMs are hinting at the potential for a couple of brief sprinkles or perhaps a very light rain shower to pass through the region (mainly the northeast corner of SoDak/wc MN) overnight in association with that cold frontal passage. It`s just that the boundary layer is so dry right now, it will be tough to get much, if any, precipitation from a passing weak shower to reach all the way to the ground overnight. A dry, high pressure day ensues for Wednesday. Then, timing it out, the second (and likely dry) frontal passage appears to work through the CWA later Wednesday night. Temperatures through the short term period are forecast to run near to slightly above normal for mid-August. .LONG TERM...(Thursday through Tuesday) Issued at 150 PM CDT Tue Aug 10 2021 The overall consensus from the longer range guidance hasn`t wavered much in the anticipated pattern shaping up across our region through this forecast period. Dry and cooler northwesterly flow aloft will persist Thursday into the start of the weekend. Temps ranging near to slightly below normal are expected then. Friday morning could start off fairly cool with readings in the low to mid 50s. Sfc high pressure will begin to pull away eastward by Saturday as an upper ridge slowly builds overhead. Warming temps and increasing humidity will return by the end of the weekend into early next week. Daytime readings in the 80s and 90s and overnight lows in the 60s will be back at that time. The next best chance for rain doesn`t appear until perhaps late Monday into Tuesday at the earliest. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 620 PM CDT Tue Aug 10 2021 Terminals KABR,KATY,KPIR,KMBG VFR skies/vsbys are expected through tonight regionwide. A cold front will move through overnight with a wind shift anticipated. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TDK SHORT TERM...Dorn LONG TERM...Vipond AVIATION...TDK
Area Forecast Discussion
National Weather Service La Crosse WI
628 PM CDT Tue Aug 10 2021 .SHORT TERM...(This evening through Wednesday) Issued at 147 PM CDT Tue Aug 10 2021 Multiple rounds of storms are possible from this afternoon through Wednesday afternoon, with the threat for severe weather and heavy rain continuing for portions of northeast Iowa and southwest Wisconsin this afternoon. The 18Z surface analysis shows the leading edge of a cold front stretching from near Omaha, NE to Rochester, MN to Bayfield, WI. The theta-e gradient and wind shift are slightly out of sync, with the lower dewpoints lagging 50-75 miles behind the wind shift. Further complicating the forecast is the presence of a stout EML and attendant BL cap that will serve to inhibit surface-based convective initiation along the advancing boundary. A remnant MCV from last night`s convection is working northeastward along the boundary and has been the focus for elevated shower/storm development along its forward flank. Across the warm sector, RAP instability profiles are pushing 3000-4000 J/kg of MLCAPE, though inhibition remains steadfast across all but the far southeastern forecast area. Effective shear profiles are also a respectable 20-30 kts, but complex hodographs would result in a quick upscale growth to line clusters. The million dollar question revolves around both IF and WHERE storms will form this afternoon. The ample convective cloud debris that has lingered over much of the central and western forecast areas has put a damper on solar insolation and destabilization immediately ahead of the true front, with rather oppressive T/Td values around 90/80 further southeast in the clearer warm sector. As the front approaches this airmass in the next few hours, the threat will increase for surface-based convection. While upper level support is modest at best with the main northern stream trough lifting into Canada, a second subtle southern stream wave centered over Sioux Falls, coupled with any accent provided by the MCV, may be enough to break the cap in true warm sector across the far southeast forecast area. Given such high NCAPE values through the hail production zone, the threat for large hail will certainly exist with any discrete cells that develop. However, with upscale growth expected to take place in short order, the threat looks to transition to damaging winds within a few hours of initiation. Where storms develop is also of some uncertainty. While the 12Z HREF inputs were quite locked on initiation taking place in far southwest Wisconsin and northeast Iowa, run-to-run consistency from the HRRR has been far less impressive. Best guess is that slightly elevated convection develops along the eastern flank of the MCV and eventually roots itself to the surface between now and 22Z. The severe weather threat should shift east/south and quickly exit the forecast area by 00-03Z, but with the front laying out in a zonal fashion this evening and lifting back north overnight, increasing H800 theta-e advection over the front--coupled with a still impressive EML, could result in a renewed threat for storms that could produce heavy rain, and hail. This threat may continue for much of the night, though the mostly parallel orientation of the low level jet to the boundary may keep the threat for heavy rain on the lower side. Onto Wednesday, the second in a pair of upper waves wraps around the main longwave trough in central Canada, which should drive the frontal boundary southeastward around midday. Additional storms may form along and ahead of the front, but the timing and coverage will depend on how the next 24 hours unfolds. .LONG TERM...(Wednesday night through Tuesday) Issued at 147 PM CDT Tue Aug 10 2021 From Wednesday night through Saturday, a longwave trough will be located just north of the area in southern Canada. Rain chances will hinge on whether any troughs are deep enough to allow showers and storms to get into our area. At this time, it looks like this only occur on Thursday and Thursday night and these rain chances will be mainly confined to areas along and south of Interstate 90. High temperatures on Thursday will be in the 80s and then it will cool to 70s for Friday...and be around 80 for Saturday. Dew points will gradually lower from the 60s on Thursday into the 50s for Friday and Saturday. The models than deviate from Saturday night through Tuesday as the ECMWF tries to maintain some troughiness over the area. Meanwhile, the GFS has a strong ridge developing over the area. Highs will be mainly around 80. Dew points will climb from the 50s on Sunday into the lower to mid-60s for the remainder of the time period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 628 PM CDT Tue Aug 10 2021 An outflow boundary from storms in Iowa and southern Wisconsin has produced MVFR conditions at the LSE taf site. The MVFR conditions will be brief...have introduced MVFR conditions for the first couple of hours at LSE in the taf period. Then...VFR conditions are expected to prevail through the taf period at both RST/LSE taf sites. A cold front will move across the area Wednesday. This will switch the wind direction from a light southerly to west to northwest late in the morning at the taf sites. Plus...there is a small possibility of showers or isolated thunderstorms to develop along the front. At this time...the higher chances will be north and east of the taf sites. Will not mention any possibility of a shower or storm in the tafs but cannot rule out the possibility of a shower or storm to impact the taf sites. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Heat Advisory from noon to 5 PM CDT Wednesday for WIZ061. MN...None. IA...Heat Advisory from noon to 5 PM CDT Wednesday for IAZ030. && $$ SHORT TERM...Skow LONG TERM...Boyne AVIATION...DTJ
Area Forecast Discussion
National Weather Service Binghamton NY
945 PM EDT Tue Aug 10 2021 .SYNOPSIS... A chance for scattered showers and thunderstorms this evening and through tonight. Hot and humid weather continues through the work week along with daily chances for afternoon scattered showers and thunderstorms. Drier and cooler weather returns for the weekend. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... The majority of showers and thunderstorms have been focused south of the region where the instability is higher. However, northern portions of the Finger Lakes northeastward to Oneida county are getting clipped by a second cluster this evening. Some adjustments with the shower and thunderstorm coverage with the late evening update for the first part of the overnight hours as another shortwave enters the twin tears. This shortwave may have just enough to kick off an additional cluster of showers and thunderstorms like the HRRR has but confidence is not high. All rain showers should be out of the area by sunrise tomorrow. For most of the region though continued the trend from the early evening update with lowering rain chances for most locations overnight. Wednesday will start out dry but will also be much more of the same during the afternoon. Ridging and southwest flow will continue to bring warm, moist air into the region, leading to another hot and humid day. A Heat Advisory is in effect for all of CNY and NEPA for tomorrow. Heat indices will approach 100, especially in valley locations. Higher elevations should be limited to the heat indices in the mid 90s. High temperatures will be in the upper 80s and lower 90s once again, and with less cloud cover expected, temperatures should have an easier time getting that high. Another shortwave is expected to pass through the region bringing afternoon showers and thunderstorms once again. Modeled CAPE values are expected to be quite high once again, with values near 2000 J/kg in the afternoon, though the NAM has values well exceeding that. Bulk shear is limited to about 20 to 25 kts. PWATs will be 1.5 to 1.8" so locally heavy rainfall is expected. Damaging wind gusts will be the main threat, but small hail might also be possible. Scattered showers and thunderstorms would be possible during the overnight hours Wednesday night and into early Thursday morning. Overnight lows are expected to be quite warm with most not dropping below 70. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... 220 pm update... Main concerns in the short term are focused on the continued heat and humidity, and threat of thunderstorms in the afternoon and evening hours both Thu and Fri. The synoptic pattern will remain defined by broad cyclonic flow across the Great Lakes and the Northeast. However, there still remains a large amount of uncertainty regarding the progression of convective complexes the day/night before and any lingering storms and/or cloud cover which would linger over the region and inhibit destabilization through the morning and into the afternoon. The persistent nature of the clouds and convection will also wreak havoc on temperature/heat index forecasts. At this time it appears most of the region will see heat indices into the mid to upper around 100 in the valleys. However, if enough cloud cover hangs around, it could ratchet those numbers down 3 to 5 deg. Model guidance is indicating a wedge of relatively drier air pushing in Thursday morning, which would allow for rapid solar insolation and a significant amount of boundary layer instability to form as temperatures climb quickly into the upper 80s and lower 90s with low 70 dew points. A couple thousand J/kg of ML CAPE and steep low level lapse rates will set the stage for deep convection later in the afternoon as yet another short wave trough pushes through central NY and ne PA. The main threats will be damaging winds and heavy rainfall. Friday will be another interesting/challenging day in determining how much early morning cloud cover lingers and also how the next incoming s/w progresses through the region. Once again, model guidance shows a narrow corridor of drier air in the morning followed by a front from the west later in the day. The difference on Friday is the slow-moving nature of the front. There does appear to be a building ridge over the Atlantic that slows down the overall synoptic movement, and will possibly result in the front checking up across the Northeast into Saturday. The combination of a deep plume of moisture...PWs around 2"...and this slow moving system could result in a threat of heavy rain/flash flooding late Friday into Saturday. Will need to keep an eye on how this system evolves through the next couple days. The heat and humidity will almost certainly continue on Friday, but with slightly lower temperatures and humidity as the drier air starts to move in from the w/nw. The hottest air will likely be over ne PA...into the lower 90s. While the Finger Lakes and Mohawk valley will be in the mid to upper 80s. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... 220 pm update... As mentioned above, the front that becomes draped across the region on Friday will linger Fri night into Saturday as the overall flow pattern slows down due to a building ridge in the Atlantic. This will likely allow for additional cloud cover and scattered showers and storms to linger/persist into Saturday afternoon...most likely east of I-81 and south of the NY/PA border. High temperatures on Saturday will warm only into the mid 70s to mid 80s with noticeably lower humidity. High pressure really pushes in late Saturday and through the rest of the weekend with dry and cooler weather expected. Sat night lows will dip into the mid to upper 50s, and highs on Sunday will only rise into the mid 70s to lower 80s under mostly sunny skies. The dry/quiet weather should persist into Monday as well, but cloud cover could be on the rise along with temperatures/humidity...back into the lower 80s for highs and lower 60s for dew points. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Mostly VFR expected through the period, however there will be a chance for isolated showers and associated restrictions at RME and SYR through midnight. ELM could also see restrictions in the morning hours with patchy fog. Tomorrow will be similar to today, with a chance for afternoon showers and thunderstorms, but confidence is too low at this time to include thunderstorms at any one location. Outlook... Wednesday Night through Friday...An active period of daily afternoon and evening scattered showers and thunderstorms, leading to occasional restrictions. Saturday through Sunday...Mainly VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Heat Advisory from noon to 7 PM EDT Wednesday for PAZ038>040- 043-044-047-048-072. NY...Heat Advisory from noon to 7 PM EDT Wednesday for NYZ009- 015>018-022>025-036-037-044>046-055>057-062. && $$ SYNOPSIS...BTL/HLC NEAR TERM...BTL/HLC/MWG SHORT TERM...BJT LONG TERM...BJT AVIATION...BTL/MPK
Area Forecast Discussion
National Weather Service Dodge City KS
1050 PM CDT Tue Aug 10 2021 ...Updated Aviation... .SHORT TERM...(This evening through Wednesday) Issued at 244 PM CDT Tue Aug 10 2021 An area of mid level showers south of I-70 was developing and shifting east in the 700 mb confluence zone over central Kansas , a notable radar fine line was also spreading south ahead of this feature and may end up having an impact of where if at all convection is able to develop this afternoon. The Convective allowing models, notably the latest HRRR run shows convection as early as 5 PM around DDc and spreading northeast along the prefrontal trough (ahead of synoptic surface front near KS/NE line. Convection wise- deep bulk shear is lack, and even effective shear is mostly below critical limits for well organized storms. The trend for effective shear appears increasing however and the surface based inhibition will still need to be overcome late this afternoon. All this points to more likely of a later than the models are showing or even less overall coverage. The good news is that the peak of hottest temperatures for the next week or more is right now, as a cooler airmass over the northern Plains influences western Kansas in the coming days. The cold front now near the NE/KS line will sag south Tonight and Wednesday. providing another focus for thunderstorms late in the day on Wednesday, with a much similar convective environment as Today. .LONG TERM...(Wednesday night through Tuesday) Issued at 244 PM CDT Tue Aug 10 2021 Overall a cooling period can be expected with high temperatures settling back into the mid 80s and low 90s for a general range over the next 7-10 days.In the short term, still very warm air will descend off the higher terrain as the surface boundary meanders over the central plains and strong mid level cyclonic jet stream flow remains entrenched over southern Canada and the Northern Great Plains/Great Lakes region. With time this will gradually retrograde the upper ridge back westward and much less hot but still summer like temperatures will be seen over western Kansas. With a weak northwest flow the setup my be one of possibility of diurnal MCS opportunity, best diagnosed on a day by day basis. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1050 PM CDT Tue Aug 10 2021 Remaining isolated thunderstorms are expected to dissipate through 06z. VFR/SKC is expected to prevail tonight and early Wednesday after convective debris clears, with a light SW wind prevailing. Kept the LBL TAF dry through Wednesday, with SW winds gusting to near 25 kts after 15z Wed. Further north, models suggest more isolated convective development near GCK/DDC/HYS during the 21z Wed - 00z Thu time range. Direct impacts on terminals are unlikely, but certainly enough confidence to include VCTS/CB in the GCK/DDC/HYS TAFs Wednesday afternoon/evening. Winds will be generally light with southerly components on Wednesday outside of convective influences. && .PRELIMINARY POINT TEMPS/POPS... DDC 72 101 70 96 / 70 20 20 10 GCK 68 100 66 96 / 20 20 20 20 EHA 68 98 66 95 / 0 20 20 20 LBL 70 99 67 95 / 10 20 20 20 HYS 71 101 70 97 / 50 10 10 10 P28 76 101 73 98 / 10 10 20 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Turner
National Weather Service Eureka CA
441 PM PDT Tue Aug 10 2021 .SYNOPSIS...Hot interior temperatures will return today and continue through the rest of the work week as high pressure builds in. Later in the week, there is a slight chance of thunderstorms over mainly Trinity County. && .DISCUSSION...Wildfires across Trinity and Siskiyou counties continues creating obscure and hazy skies over Trinity, Humboldt and Del Norte counties. HRRR smoke guidance indicates this conditions remain generally unchanged over the next 24 to 36 hours. Meanwhile, coastal stratus linger along the Mendocino Coast and is expected to advect into the Redwood Coast tonight. Otherwise, the marine layer is expected to remain shallow through the work week with a strong low level inversion as the high pressure build over the area. The upper ridge will support hotter temperatures across the interior. There is a bit of uncertainty regarding the coverage and opacity of smoke over those areas. High temperatures could potentially be several degrees cooler in areas of thicker smoke, and persistent smoke could allow long wave radiation to escape at night, further reducing the heat risk. As a result, Heat Advisory is in place to cover the areas most likely to see the heat risk on Wednesday and Thursday. Worst case scenario, there will be isolated pockets that experience excessive heat, but feel this event will be better handled by an advisory. The mid and upper level monsoonal moisture is expected to move from the south across the area late Wednesday night and linger into the weekend. Some model guidance are suggesting some instability will be present in portions of the Lake and Mendocino counties late Wednesday night. The CAMs guidance show weak convection returns aloft approaching the area during this period. Other than that, confidence remain low with a non-zero probability of convection expected. Meanwhile, enough elevated CAPE is expected to be present beginning on Thursday afternoons. The moisture combined with strong surface heating and steep mid level lapse rate will support to isolated thunderstorms across portions of mainly Trinity County. Otherwise, model guidance shows monsoonal moisture lingering across the area on Friday and a slight chance for an isolated thunderstorm will exist mainly over northern Trinity and into northeast Humboldt counties. && .AVIATION...Smoke from inland wildfires has been spreading over coastal terminals, resulting periods of MVFR ceilings and vsbys at KACV and KCEC. Shallow stratus has also been rounding Cape Mendocino this afternoon and should advect into the coastal terminals this evening and overnight. Conditions appear favorable for fog, perhaps dense at times, with vsbys of 1/4SM or less by early Wednesday morning. Shallow stratus and fog should quickly erode on Wednesday, but may linger near the shoreline all day with periods of IFR or LIFR. Other than the smoke from the wildfires in Trinity County, VFR conditions are expected to prevail across the interior and at KUKI through the period. && .MARINE...An advisory for small craft has been extended through tonight across the outer waters due to steep seas, 6 ft or more. Conditions will begin to subside below advisory thresholds Wednesday morning as northerlies offshore continue to diminish. Otherwise, lighter winds and lower seas are expected for remainder of the week as surface gradient relax. Northerly winds may start to increase to advisory level of 21kt or more this weekend south of Cape Mendo. && .FIRE WEATHER...Warmer temperatures are expected from today through the end of the week as high pressure builds over the area. Winds will be generally diurnal and terrain-driven for the next several days. Dry daytime RH values will continue across Trinity, E Mendocino, and Lake counties. Inland nighttime RH recoveries will be fair through the week, with maximum humidities not rising out of the 30-40% range in many interior areas save for valley locations. Isolated dry thunderstorms are possible across portions of Trinity County Thursday and Friday afternoon and evening. /SEC && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory from 1 PM Wednesday to 5 PM PDT Thursday for CAZ107-108-110-111-113>115. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 3 AM PDT Wednesday for PZZ470. Small Craft Advisory until 8 PM PDT this evening for PZZ475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Grand Junction CO
529 PM MDT Tue Aug 10 2021 .SHORT TERM...(Tonight through Wednesday night) Issued at 250 PM MDT Tue Aug 10 2021 Shortwave dragging across the Northern Rockies and sliver of moisture overhead, evidenced by subtle uptick in the 12Z GJT sounding (0.57 PWAT), has sparked a few showers/storms over the higher terrain across northeast Utah and northwest Colorado, general along and north of the I-70 corridor. Storms tracking ESE and picked up well in earlier HRRR runs. Convection diminishes near sunset with gusty winds being the primary threat from these high-based cells. Ridging builds back on Wednesday with the airmass drying back out over the northern two-thirds of the forecast area as PWATS are forecast to tumble below 0.25". Fairly steep moisture gradient anticipated in the vicinity of our southern mountains with where PWATS are expected nudge up to near three-quarters of an inch by late Wednesday. Convection tends to favor these gradient locations out here and with plenty of heat and instability, would expect to see a few storms over the San Juans down into the Pagosa Springs region. Will juice POPS up in this area with low end scattered coverage, otherwise it`s a dry and smokey day for the majority of eastern Utah and western Colorado. No major swings in temps for the next 36 hours with hot daytime temps and mild overnight conditions continuing. .LONG TERM...(Thursday through Tuesday) Issued at 250 PM MDT Tue Aug 10 2021 High pressure currently situated just off the Pacific NW coast will slowly move eastward in the long term periods, stretching across the western CONUS. With this setup in play, expect the hot day time temperatures to remain. At least in the next few days, the pattern won`t exactly be ideal (with high pressure centered further west), it looks like some sporadic monsoonal moisture will move into southwestern / west-central Colorado and adjoining Utah by late this week. This will probably lead to just as much rain as wind (until additional moisture builds into the area, anyway). Although fairly large differences remain between model tracks, a large trough looks to drop south over the northern CONUS next week. This would lead to cooler temperatures, leaving almost all of CWA below average for this time of year. This system would also bring increasing chances for showers as the monsoonal flow becomes more ideal for a period of time next week. This pattern change to more southerly winds would also aid in smoke dispersion out of our area. Unlike a a couple weeks ago, this appears to be a fairly short-lived monsoon surge and isn`t likely to maintain a sustained push...which would be closer to a `normal monsoon` season if there is such a thing. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 525 PM MDT Tue Aug 10 2021 Gusty outflow winds from storms firing along and north of I-70 will continue to propagate southward and weaken by 03Z. Light, terrain driven winds will take over during the night and tomorrow morning. Smoke remains a concern for most TAF sites across eastern Utah and western Colorado through the next 36 hours with improving conditions possible Wednesday afternoon as breezy conditions redevelop after 18Z. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...JDC LONG TERM...SS AVIATION...ERW
Area Forecast Discussion
National Weather Service Grand Rapids MI
740 PM EDT Tue Aug 10 2021 LATEST UPDATE... Update/Aviation .SYNOPSIS... Issued at 311 PM EDT Tue Aug 10 2021 - Risk for Severe Weather Tonight into Thu - Cooling off and drying out over the weekend && .UPDATE... Issued at 740 PM EDT Tue Aug 10 2021 Over WI, it`s been quite an imbalance between very strong instability (MLCAPE greater than 4000 J per kg) and very weak shear (0-3km bulk less than 20kt). However it looks like things are starting to gel together a bit more so a more contiguous cold pool can develop. Also, there is recent quick development over IL in even greater instability - and surprisingly this appears more balanced and may bring our greatest risk for damaging winds. The HRRR is aggressive in maintaining rather intense convection into Lower MI, but we are leaning more in favor of the 18Z NamNest which showed more of a splash-out evolution from the WI convection. That said, no model is really handling the IL convection well, so that will be a big thing to watch in the coming hours. && .DISCUSSION...(This evening through next Tuesday) Issued at 311 PM EDT Tue Aug 10 2021 - Risk for Severe Weather Tonight into Thu A shortwave in IA is forecast to track through Lower MI later this evening. Ahead of it a very unstable airmass exists. Thunderstorms were already developing in IA ahead of this feature. Also the outflow from the storms in the UP is dropping southeast...reaching now into southeast MN and Northwest WI. A low level jet is shown to point into the CWA ahead of this convection which increases the risk for storm potential. The high res models seem to locking on to the storms in IA building and expanding northeast into southeast WI and eventually southwest Lower MI. Damaging winds and large hail are the primary risks. The broad mid level trough sinks south Wed into Thu. Mid level winds increase across the CWA then. This will help to strengthen the deep layer shear. Initially on Wednesday there may be debris clouds from the overnight convection. However instability builds through the afternoon and storms may get going by 18z. This initial convection may be isolated. However later at night ther are some indications for a forward propagating MCS to develop. Based on the strength of the forecast deep layer shear and strong instability...very close monitoring of this pattern is needed. A west flow develops on Thursday which may act to keep the strongest convection off to the south to southeast parts of the CWA. This is where SPC has the marginal risk. - Cooling off and drying out over the weekend && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 740 PM EDT Tue Aug 10 2021 No changes to previous TAFs except to refine timing for thunderstorms at MKG. We see very recent development of strong storms over IL and these could affect the AZO and BTL terminals later tonight if they hold together. As it stands now, all terminals feature at least some VCTS and this may need to be amended to an hour (or two) of prevailing before 06Z, but this would most likely to happen at MKG, AZO, BTL, and GRR if at all. && .MARINE... Issued at 311 PM EDT Tue Aug 10 2021 We did issue small craft advisories and beach hazards for parts of the region. Southwest wind will increase up to 20 knots or better late tonight as a front approaches from the west. This will act to build the waves...especially north of Holland. The hazardous conditions will likely persist into Wednesday evening. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement from Wednesday morning through late Wednesday night for MIZ037-043-050-056. LM...Small Craft Advisory from 5 AM Wednesday to 3 AM EDT Thursday for LMZ844>849. && $$ UPDATE...TJT SYNOPSIS...MJS DISCUSSION...MJS AVIATION...TJT MARINE...MJS
Area Forecast Discussion
National Weather Service Lincoln IL
923 PM CDT Tue Aug 10 2021 .SYNOPSIS... Issued at 330 PM CDT Tue Aug 10 2021 Heat and humidity will remain very high through Thursday, then a cold front should bring some relief Friday through the weekend. Daily chances for thunderstorms will take place through Friday. The potential of severe thunderstorms will be present through Thursday, but the highest chances during that time will be tonight. && .UPDATE... Issued at 922 PM CDT Tue Aug 10 2021 Scattered storms are still moving across the northern part of the area and will continue to move east out of the area after 10 pm. However, another round of showers and storms is expected to develop along an outflow boundary that will be sitting across the northern part of the area. These storms are expected to develop around midnight along the intersection of the boundary and the low level jet coming in from the southwest. Actual location depends on where boundary sets up but seems somewhere along or north of a Fulton to Mclean county line looks reasonable. Some of the HiRes models support this as well. Some storms could be strong to severe as well, but locally heavy rainfall and potential flash flooding are also possible. Forecast looks pretty good, but going to make some adjustments and send an update shortly. && .SHORT TERM...(This evening through Wednesday) ISSUED AT 330 PM CDT Tue Aug 10 2021 Varying triggers for convection will potentially be affect central IL late this afternoon and tonight. The 12z HRRR indicated a bow echo blasting across central Illinois this evening, as a continuation from the storm complex in northern Missouri. The 18z HRRR now dissipates all of that convection and the line of storms east of St Louis before they even reach our CWA, finally bringing a complex of storms from northern Illinois into our northern counties late this evening and overnight. Those kinds of changes/differences are abound between the high resolution models, making a very challenging short-term forecast. Warming cloud tops from the Missouri complex is giving some confidence that that system may be weakening as the 18z HRRR now shows. The line of storms headed toward SE Illinois is maintaining and even expanding northward in the last 30 mins. The latest satellite and radar trends indicate the wave coming out of Missouri will expand eastward early this evening across central IL, with large instability available for intense updrafts/downdrafts as well as very heavy rainfall. MLCAPEs over 4500 J/kg will be widespread in our CWA, along with Effective shear of 25 kts. That round of storms will shift east as additional storms develop in west-central Illinois. Later this evening and overnight another round of storms could advance into our northern counties ahead of a pre-frontal trough across central Iowa. That complex would have the potential of widespread damaging winds as it evolves into a bowing line. PWATs still over 2" will support more very heavy rainfall to areas that picked up decent amounts of rain in the last couple of days. Flash flood threat will be present under that scenario. Overall updates to the forecast today were to increase PoPs to likely tonight across the northern counties where higher potential of storms tonight exists, closer to the mid-level speed max across N IL. Will closely monitor short-term trends in the models to stay ahead of the system evolution. The lack of an airmass change tonight will set the stage for Wednesday to be another very hot day, with 105-110F heat indices likely across entire CWA. Another heat advisory will be issued for Noon to 7 pm Wed for those conditions. Various outflow boundaries will be present on Wednesday, with even some morning storms still ongoing at sunrise. Any outflow boundaries would be a focus for strong to severe storms again tomorrow afternoon and evening. SPC Day 2 expanded the Slight Risk farther south into central IL, which is supported by another day of 4K J/kg MLCAPE and 8C/km mid-level lapse rates. Marginal shear will once again be the limiting factor for widespread severe storms. .LONG TERM...(Wednesday night through Tuesday) ISSUED AT 330 PM CDT Tue Aug 10 2021 Strong to severe storms will likely be present Wednesday evening, and possibly into the overnight again as a nocturnal speed max impinges upon northern Illinois. A more uncertain storm scenario will be present on Thursday, but a corridor of moderate to high instability will be present across Illinois from SW to NE. An SPC Day 3 Marginal Risk of severe storms is in place across our entire CWA, with potential of a slight risk upgrade in portions of the area, as the overall weather pattern takes shape tomorrow. A cold frontal passage on Friday will bring more storms, with yet another threat of severe weather per the SPC Day 4 outlook, especially in east-central IL. That FROPA will signal the arrival of noticeably cooler and less humid air. Highs will return to the lower 80s through the weekend and continuing through Tuesday. The weekend looks dry, but rain chances creep back into the forecast on Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 646 PM CDT Tue Aug 10 2021 Expecting VFR conditions at all TAF sites next 24hrs, except when convection is on site and vis is reduced to around 4sm. So, believe SPI/DEC/CMI will not see any precip this evening or overnight as convection has already developed well north of this area and is actually headed toward PIA and BMI. Clouds over this area are also quite smooth and not seeing any development in satellite loop over this area. Expecting mid level cigs around 8-10kft this evening and overnight but then become lower tomorrow in the afternoon...when could be some storms, but probably after end of current TAF period. PIA and BMI will see more convection this evening as storms that have developed along the Miss river will move toward these sites early this evening. HiRes model shows this scattered convection continuing through this evening and overnight with best chance on station from 08-12z...which is when there is a TEMPO group. Convection near PIA and BMI should around 15z and then remain dry for the afternoon. Expect more convection late tomorrow afternoon, but timing is unsure. Winds should be south to southwest through the period with gusts around 20kts this evening, then becoming lighter, but still around 10kts through rest of the period. && .ILX WATCHES/WARNINGS/ADVISORIES... Heat Advisory from noon to 7 PM CDT Wednesday for ILZ027>031- 036>038-040>057-061>063-066>068-071>073. && $$ UPDATE...Auten SYNOPSIS...Shimon SHORT TERM...Shimon LONG TERM...Shimon AVIATION...Auten
Area Forecast Discussion
National Weather Service Marquette MI
641 PM EDT Tue Aug 10 2021 .SHORT TERM...(This evening through Wednesday) Issued at 508 PM EDT TUE AUG 10 2021 Water vapor imagery and RAP analysis show a deepening trof into s central Canada. The negative height anomaly with this trof will become fairly deep as it shifts to Hudson Bay over the next 2 days. This deepening trof will phase with a vigorous shortwave currently e of Lake Winnigeg. With this vigorous wave pivoting ne, the tail end of its deep layer forcing is just brushing the Upper Great Lakes. As a result, a cluster of tstms developed near the Twin Cities late this morning. Those storms then increased in coverage as they shifted ne across western Lake Superior and the w half of Upper MI today. Given the rather significant cinh for sfc based convection, the storms have remained at least slightly elevated. This cinh has been gradually diminishing though. MLCAPE is around 1500j/kg vcnty of the ongoing convection but does increase to over 2000j/kg toward KIWD. Highest wind gust observed with the storms so far has been 41kt when the storms moved across KIWD. Otherwise, there have been no svr storm reports. Given the impressive storm cores seen well above the freezing level in some of the storms, have to believe some large hail and/or damaging winds have occurred in a few spots. Ongoing convection will continue for the next few hrs. However, as the forcing from the aforementioned shortwave exits to the ne, the storms should begin to diminish with much of the activity probably done by 00z. The night should then be on the quiet side as we await a shortwave moving thru the upstream deepening trof. Looks like nocturnal inversion will be sufficiently strong for at least some fog to develop, especially late night across the e half of the fcst area under very light southerly sfc wind. Shortwave and associated cold front will then reach Upper MI during Wed. MLCAPE increases to 1000-2000j/kg ahead of the front, greatest from the s central fcst area eastward. Deep layer shear of at least 40-50kt will support organized storms. So there will be a risk of svr storms for the central and eastern fcst area given the expected timing of the front. Depending on cloud cover, max temps should reach the low to mid 80s F in general. .LONG TERM...(Wednesday night through Tuesday) Issued at 302 PM EDT TUE AUG 10 2021 The long-term period looks to be dominated by a drier conditions, with cooler conditions expected Thursday and Friday due to a cold front, and warmer conditions expected early next week as ridging builds across Upper MI. May see some showers and thunderstorms in the far east early Wednesday night as some a cold front looks to finish moving through the area. Severe weather potential looks decreased from the afternoon hours Wednesday, with the potential for any precip falling fast in the early evening hours. As a wave of CAA behind the front moves across the U.P. Thursday, expect high temperatures to be cooler, with the upper 70s expected across the west and low 80s across the south and east. The east and south should get warmer behind the front as the stronger CAA should move over these areas later in the day Thursday. May see a rain shower or two over the far east, given the forcing from the CAA, winds over Lake Superior and MI converging, and abundant moisture in the mid levels. However, the occurrence of these showers is questionable, as there is fairly dry air in the upper levels of the atmosphere and near the sfc; thinking all those ingredients would have to come together to really get anything. Expect the coolest day to be Friday as troughing from the cool, Canadian air stops digging over Upper MI; expect highs to only get into the low to mid 70s and lows to bottom out to the mid 40s in the interior west. This weekend, WAA is expected to build across the U.P. as ridging begins to move over the area. May have some shortwaves roll along the ridge as it progs across us. However, models show the ridge strengthening across the U.P. until near the end of the extended period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 641 PM EDT TUE AUG 10 2021 VFR conditions will continue through the forecast period at IWD and CMX. At SAW, with rain from the previous thunderstorms that moved through, fog will be possible overnight and will fall to MVFR at least. Otherwise, SAW will remain VFR through the period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 508 PM EDT TUE AUG 10 2021 Deep low pres for Aug will be moving across Hudson Bay over the next couple of days. To its s, a low pres trof will move across Lake Superior tonight. Two cold fronts will then follow, one passing on Wed and the second on Thu. Expect s to sw winds gusting upwards of 15-20kt at times across Lake Superior tonight. With the first cold front Wed, sw winds will increase further over the w half of Lake Superior with some gusts to 20-25kt expected to develop, especially btwn Isle Royale and the Keweenaw. With the coolest air following the second front and with incoming pres rises, westerly winds on Thu will likely frequently gust to around 25kt across most of Lake Superior. Winds should then fall back to mostly blo 20kt Fri and then mostly blo 15kt over the weekend as high pres drifts e across the Great Lakes region. Finally, lingering areas of fog on Lake Superior should clear out from w to e during the night tonight. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Dense Fog Advisory until 8 PM EDT this evening for LSZ245>251- 264>267. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...TAP AVIATION...07 MARINE...Rolfson
Area Forecast Discussion
National Weather Service San Diego CA
710 PM PDT Tue Aug 10 2021 .SYNOPSIS... A complex of thunderstorms over Arizona will race southwestward and could move into the Coachella Valley and San Diego County deserts late this evening, moving across the mountains while dissipating overnight. Additional monsoonal thunderstorms are expected to develop over the mountains Wednesday afternoon, potentially impacting the adjacent valley and desert regions as well. Locally heavy rainfall and isolated flash flooding will be possible near thunderstorms. Drying will occur Thursday through Friday with decreasing chances for thunderstorms. Monsoonal moisture may increase some again for Saturday through Monday with chances for afternoon and early evening thunderstorms in the mountains and deserts. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Update: * Thunderstorms could hit the Coachella Valley/SD Deserts by 11 PM * Flash flooding and strong winds/blowing dust is possible * Tstorms could move west and over the SD mountains overnight A very interesting evening here with all eyes on a formidable thunderstorm complex racing southwestward from Arizona into SE California. This band of strong-severe thunderstorms has an arching outflow boundary, producing blowing dust along it. The airmass ahead of this complex of tstorms is unstable and tropical with surface- based CAPE 1000-3000 J/KG and PW at 1.5 inch over the Riverside and San Diego County mountains increasing east and south to 2 inches over SE California per SPC mesoanalysis. This is impressive monsoonal moisture. Given current satellite and radar trends, the past several runs of the HRRR are believable and they show this complex moving into the Coachella Valley (especially southern portions) and SD deserts between 11 PM and midnight then over the mountains with even isolated cells making it all the way to the coast and offshore overnight. The big concern is the flash flood potential over the lower deserts and the San Diego County mountains overnight. Rainfall rates could reach 1" to even 2"/hr in the strongest cells over the deserts and mountains overnight. Thus, have expanded the Flash Flood Watch to include the Coachella Valley and San Diego County deserts. The period of highest potential impact for the lower deserts and the San Diego County mountains is from 11 PM to 3 AM. The low level surge in winds out of the northeast could bank up against the mountains, increasing low level convergence, possibly allowing cells to even gain strength over the lower deserts and SD mountains/desert slopes. Strong gusts along the leading edge of the thunderstorms could trek across the lower deserts as well, leading to severe visibility restrictions in blowing dust before heavy rains hit, so we`ll be watching this potential as well. Again, a few showers or thunderstorms could even make it west of the mountains and to the coast, but they will weaken dramatically once west of the mountains as they run into a more stable atmosphere. The forecast has been updated to account for all of this as described above. A potentially very active night lies ahead for southern parts of our service area. Previous Discussion (Issued at 133 PM PDT Tue Aug 10 2021): Several thunderstorms have erupted in the mountains today and will continue to develop and dissipate into this evening. Most will be in the mountains, but the deserts will have an increasing chance through the evening. The farthest inland valleys may also get some thunderstorms drifting off the mountains. For tonight, a minority of guidance suggests very powerful storms in Arizona or the far southeast CA desert late tonight could migrate westward into our region as they collapse and weaken. Believe we should get some leftover showers later tonight and Wednesday morning in the mountains and deserts. But we`re keeping an eye out for the smaller chance that the stronger stuff could occur. Wednesday afternoon and evening look very similar for the coverage, timing and intensity of rain as today. Rates either afternoon in thunderstorms could reach 1.25+ inches per hour, which would be sufficient to trigger flash flooding, but this rate would be very isolated. Much less (0.50 in/hr) would do the trick in burn scars like the Apple and El Dorado. Obviously, flash flooding and debris flows are our biggest hazard concern through Wednesday, as indicated by the flash flood watch. Near the coast, the marine layer will take a step or two backward while the monsoon push takes center stage. On Thursday and Friday the moisture decreases gradually, although there`s still a slight chance of afternoon thunderstorms in the mountains and high desert Thursday afternoon. Right now it appears too dry for any chance Friday. The coastal clouds will be patchy at most during nights and mornings these days. Inland temperatures will fluctuate near normal, but a few degrees above normal this weekend. This weekend we`ve been watching various forms of another increase in monsoonal moisture, maybe in the form of an easterly wave. Recent model runs have backed off a bit and ensembles show less organization and lower confidence. The chance of afternoon thunderstorms mainly in mountains should return Saturday, possibly peaking Sunday and Monday afternoons. Ensembles are showing greater confidence in a West Coast trough gradually developing next week that would sweep away any monsoon moisture to the east. Right now we`re forecasting a dry Tuesday, but that question will be revisited many times before then. Growing confidence that the trough next week will gradually trend us toward cooler and drier, and the trough would also help rebuild the marine layer and coastal cloud regime. && .AVIATION... 102000Z...Coast/Valleys...Locally FEW clouds with bases 1000-1500 ft MSL at the beaches. Patchy low clouds becoming more widespread at the beaches after 06Z Wed with bases lowering to 500-1000 ft MSL. Cigs expected to form at coastal TAF sites 07-11Z Wed. Local vis restrictions of 3-5SM where low clouds meet higher coastal terrain. Low clouds expected to clear 15-17Z Wed. There is a slight chance of TSRA in the valleys from 21Z-03Z Tue. CB bases would be around 10,000 ft MSL and tops to 25,000 ft MSL along with strong up/downdrafts and local strong gusty surface winds. Otherwise, mostly unrestricted vis will prevail with occasional SCT/BKN clouds AOA 10,000 ft MSL through Tue evening. TSRA possible in the valleys again Wed afternoon. Mountains/Deserts...SCT TSRA over the mountains and locally into the deserts. CB bases are around 9,000 ft MSL with tops to 45,000 ft MSL. Strong up/downdrafts and local strong gusty surface winds expected near TSRA, with local vis below 3 miles possible. Thunderstorm activity expected through 04Z Wed. Slight chance of -RA overnight. SCT TSRA expected again Wed afternoon. && .MARINE... No hazardous marine conditions are expected through Sunday. && .SKYWARN... Skywarn spotter activation may be needed Wednesday afternoon for thunderstorms expected to develop over the mountains and movement into the valleys/deserts. Spotters can self-activate safely and report any heavy rain/wind/dust associated with a complex of thunderstorms poised to move into the lower deserts and potentially across San Diego County overnight while weakening. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Flash Flood Watch through Wednesday evening for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains- San Bernardino County Mountains-San Diego County Deserts- San Diego County Mountains-San Gorgonio Pass Near Banning. PZ...NONE. && $$ PUBLIC...Gregoria (Update)/MM (Previous Discussion) AVIATION/MARINE...MM
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