Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/26/20

Area Forecast Discussion
National Weather Service Lincoln IL
852 PM CDT Fri Sep 25 2020 .SYNOPSIS... Issued at 332 PM CDT Fri Sep 25 2020 Summer-like conditions will be on tap across central Illinois on Saturday as afternoon high temperatures soar into the middle 80s. The next chance for rain will arrive Sunday evening through Monday as a strong cold front passes through the region. && .UPDATE... Issued at 852 PM CDT Fri Sep 25 2020 Except for a few clouds in the southeast and the high cirrus moving into the area, skies are clear across the CWA. With dewpoints ranging from 58 to 63, current overnight low forecast of around 60 continues to look reasonable. Remainder of the forecast looks fine as well, so no need for an update at this time. && .SHORT TERM...(This evening through Saturday) ISSUED AT 332 PM CDT Fri Sep 25 2020 Lingering cloud cover from Shelbyville/Mattoon southward will dissipate before sunset, with clear skies expected across the board this evening. Several short-term models such as the HRRR suggest low clouds will re-develop within the WAA regime late tonight into Saturday morning...particularly along/southeast of a Danville to Shelbyville line. Given the fact that nocturnal cloud cover failed to completely clear across the SE KILX CWA today, think re-development tonight seems plausible. As a result, have gone with partly to mostly cloudy skies along/south of I-70 from shortly before dawn through mid-morning Saturday. Elsewhere, mostly clear skies will be the rule. As the pressure gradient tightens ahead of an approaching cold front, southerly winds will increase during the day Saturday. Forecast soundings and numeric guidance both indicate gusts of 25-30mph, with the strongest winds focused along/west of I-55. Given the strong southern flow and ample sunshine, afternoon highs will rise well into the 80s. .LONG TERM...(Saturday night through Friday) ISSUED AT 332 PM CDT Fri Sep 25 2020 The cold front will settle into central Illinois on Sunday: however, the airmass will initially be quite dry, so precip will be slow to materialize. As the profile gradually moistens, a few showers may occur during the afternoon. The best rain chances will hold off until Sunday evening when a band of frontogenetic forcing develops along/behind the surface front. All models show showers becoming more widespread, resulting in high chance to likely PoPs across all but the far E/SE CWA. As the front shifts further east and a surface low tracks northward along the boundary, showers will continue into Monday as well. The latest NAM/GFS show little to no elevated instability, so have decided to drop any mention of thunder. Rainfall totals with this system will generally range from one half to three quarters of an inch. Once the front exits, showers will taper off and come to an end by Monday night, followed by cooler conditions with highs only in the 60s for Monday/Tuesday. After a brief warm-up on Wednesday, a reinforcing surge of cool, Canadian air will drop highs into the upper 50s and lower 60s by Thursday and Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 704 PM CDT Fri Sep 25 2020 VFR conditions will prevail at all TAF sites next 24hrs. Looks like more smoke, from fires in WY and CO, is moving this way, so have included SCT250 for the entire TAF period. Winds will be southerly through the period with wind speeds less than 10kts tonight, then increasing tomorrow morning with gusts around 20kts in the morning, but increasing to around 25-27kts during the afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Auten SYNOPSIS...Barnes SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Auten
Area Forecast Discussion
National Weather Service Northern Indiana
740 PM EDT Fri Sep 25 2020 .SYNOPSIS... Issued at 739 PM EDT Fri Sep 25 2020 Expect warm conditions to continue through the weekend with highs in the lower to middle 80s. It will turn markedly colder early next week, along with periodic rain chances. && .SHORT TERM...(This Evening through Saturday) Issued at 340 PM EDT Fri Sep 25 2020 Low level moisture held south along the Ohio River Valley with ridging from western Pennsylvania through Indiana to Arkansas. High will move east into Appalachia overnight with low level flow quickly veering. Some concern that mixed low level moisture advecting northward to form stratus deck near/shortly after daybreak over CWA. While that is within the realm of possibilities, HRRR and observed expanse of dry, subsident air in place/lower 50s dewpoints in CWA, timing of veering could maintain this moist pool south of CWA through mid morning. Thermal moderation continues with highs into the lower/middle 80s next two days. && .LONG TERM...(Saturday Night through Friday) Issued at 340 PM EDT Fri Sep 25 2020 Attention remains on digging northern stream flow pattern early next week. Discount of EC per outlier solution digging strong cutoff from the Upper Midwest into the Lower Mississippi Valley versus developing less intense Upper Great Lakes circulation, as per NAM/GFS. EC outlier for past few runs and continued lack of support seen in GFS/GEFS members. That said, overall trend of later arrival of moisture/slower evolution of and anafrontal/successive waves with pops now relegated to late Sunday afternoon far northwest. Thereafter, have followed blend, concur with highest pops Monday afternoon into Tuesday as system deepens over Lake Huron into Ontario. A few degrees below blend for highs Tue through Thu with nod to consistency, anticipated thick cloud cover/showers. Expect Monday through Wednesday beach hazards with potential for low end gales/minor beach erosion. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 739 PM EDT Fri Sep 25 2020 Predominantly a VFR condition are expected at the terminals through the period, with the exception of potential for IFR conditions late tonight into tomorrow morning as low level moisture is advected into the region. Gusty south-southwest winds will pick up and mix conditions out by late afternoon. Model guidance is varying quite a bit as to how low ceilings will get, ranging from continuing VFR to around 600-1500 ft. Kept previous forecast of 600 feet for now, can see how things evolve upstream before && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...MCD SHORT TERM...Murphy LONG TERM...Murphy AVIATION...MCD Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Marquette MI
726 PM EDT Fri Sep 25 2020 .SHORT TERM...(This evening through Saturday) Issued at 409 PM EDT FRI SEP 25 2020 Split flow pattern continues across the CONUS with numerous short waves embedded in the northern stream flow. The important one for our forecast is one over Minnesota in the SPC mesoanalysis. dCVA out ahead of it, plus fgen in the 850-700 mb layer and about 1000 J/kg MUCAPE out ahead of the front has allowed a few thunderstorms to pulse up in northern Minnesota per radar and satellite. Closer to home, satellite shows lingering stratus continuing to mix out into a scattered cloud deck. Insolation in between the clouds has allowed temps to rise into the low 70s over much of the U.P. with dew points in the low to mid 60s, except 59 at Houghton. Those dew points are right in line with where the NAM, RAP, and RGEM have them, so for once the models aren`t actually running too high on low-level moisture. Mesoanalysis shows 500 J/kg MLCAPE nudging into Gogebic County which is also right on schedule or perhaps even slightly ahead of schedule relative to model progs of instability. For the severe weather threat this evening, still haven`t seen much change today from the thinking this morning. Still expecting MLCAPE to increase across the west half through this evening to around 1000- 1500 J/kg and a 30+ kt LLJ at 00z strengthening to 40+ kt by 03z leading to 0-3 km SRH of 200-300 m2/s2 or more and 0-6 km bulk shear vectors of 40-50 kts or more. The surface front is oriented NNE to SSW, so WSW shear vectors are nearly perpendicular, although things get a little less clear over the Keweenaw where the effective front becomes more zonally oriented thanks to the marine layer to the north. So there could be some training of cells and upscale growth into a QLCS up there, but elsewhere supercells look possible. The only question now is far south convection develops, given there is still a cap in place. The HRRR has been very consistent throughout the day in developing cells over the Bayfield Peninsula around 22- 23z and then driving them northeastward along the western shoreline and onshore north of Ontonagon. That`s pretty much exactly what the POPs reflect from this morning, so made only minor tweaks to the POPs, thunder, and severe potential grids this afternoon. Still think the main time frame to watch will be 00-04z this evening. The modeled combination of bulk shear, low-level shear/helicity, MLCAPE, and mid-level lapse rates around 7 C/km should support all severe hazards with large hail, damaging winds, and a tornado or two all possible. Flash flooding looks unlikely given fast storm motions and storm motion vectors not parallel to the boundary, although if there was to be any it would be over the Copper Country given the aforementioned orientation of the boundary locally. Once storms lift off to the northeast, the wind veers around to westerly behind the front. High dew points and heavy rain falling over Lake Superior will likely generate areas of fog that will then be advected onshore into the western U.P. Models are all pretty aggressive with low-level saturation, especially over the Copper Country, which makes sense. The SW flow becomes downslope over the central U.P. so not expecting any fog there. This low-level moisture and lingering cloud cover will keep temps up near 60 through the night, making it feel a lot more like July than late September. Tomorrow, with the front sagging south into Wisconsin, it`s looking dry to start the day, although high cloud cover will persist throughout the day. But by late afternoon, another mid-level short wave will be approaching from the west embedded within the cyclonic flow around a strong wave setting up in the Canadian Prairies. Mid- level theta-e advection and moisture convergence will increase in a west-east band on the nose of another 35-45 kt LLJ by about 21z, although model soundings show a dry layer below that so it may take a little time to saturate the column and generate showers. Right now, think thunderstorms will hold off until just after 00z, so will let the thunderstorm chance be discussed in the long-term AFD. .LONG TERM...(Saturday night through Friday) Issued at 439 PM EDT FRI SEP 25 2020 Main story in the long term is the trend toward increasingly colder conditions next week. Broad troffing currently from the N Pacific to western Canada features 2 anomaly centers, one near the Aleutians and the other roughly along the western coast of Canada. The latter will dive into the central U.S. this weekend as ridging builds into western Canada downstream of the former anomaly. Then during next week, the western ridge will become sharply amplified, building northward to the Arctic, forcing the central U.S. trof to become established over eastern N America with axis from eastern Hudson Bay/nw Quebec s thru the Great Lakes region. For Upper MI, this obviously spells a trend to colder weather with time next week. Temps will still be above normal thru the weekend, fall somewhat blo normal early next week, then drop to solidly blo normal by the end of the week. Per CFSv2, this cold pattern should not be persistent as it has been consistently indicating above normal temps overall for the month of Oct. As for pcpn, in advance of the developing trof into the central U.S., a shortwave will move across the northern Great Lakes Sat night, bringing shra/some tsra. Then, expect periodic shra next week as mid-level trof evolves eastward to the Great Lakes. By midweek and certainly by late week, there will be a lake component to the shra as air mass becomes increasingly colder. Will probably see the first graupel showers or snow flakes of the season late week as well. Overall, the weather next week will be unsettled. Won`t be showery all the time, but there also won`t be any extended dry time. Beginning Sat night, shortwave will track from the Dakotas and MN to Lake Superior. There may end up being 2 streaks of heavier pcpn from this wave, one closer to the vort max track, across Lake Superior and nw Upper MI under better dynamics/more favorable upper diffluence with the associated jet streak, and the second (favored by the CAMs) focused vcnty of the remnant of the boundary that settles over or just se of the fcst area tonight. Increasing low- level jet/theta-e advection supports the convective development there. There is still some uncertainty in where the axes of the 2 pcpn areas will be located. For now, fcst will generally reflect a sw-ne zone of lower pops roughly across the central fcst area, btwn streaks of higher pops/heavier qpf across the nw and se fcst area. Storms should be elevated, and with MUCAPE in the 1-3km layer up to 1000j/kg and with effective shear likely to be in excess of 40kt, there will be organized storms and a svr risk, mainly hail. With precipitable water near 200pct of normal, hvy rainfall will also be possible. A dry day should follow on Sun. However, upper diffluence associated with right entrance of sw-ne oriented 130kt upper jet streak across Lake Superior will support some shra to the s and e, but they may still just brush the far se and eastern fcst area. Sun will be the last mild day with highs mostly in the mid/upper 60s. Deepening mid-level trof will then evolve eastward to the Great Lakes region during the week. Whether a wrapped up fall storm emerges from this trof to impact Upper MI remains to be seen, but bulk of recent guidance over the last day or 2 suggests any deep low pres that might develop would likely be far enough e and ne of the fcst area so that no significant affects would occur here. Otherwise, a series of shortwaves dropping into the trof, cyclonic flow and increasingly colder air with time will lead to frequent episodes of shra thru the week. These shra will also become lake aided with time as air mass becomes colder. By the end of the week, GFS/ECMWF/CMC ensemble mean 850mb temps of -3 to -6C (GFS coldest), would support some potential of the first graupel showers or snow flakes. By late week, high temps will only be in the mid 40s to lwr 50s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 725 PM EDT FRI SEP 25 2020 A cold front continues to move toward Upper michigan this evening, triggering showers and thunderstorms over western Lake Superior. This activity will spread east into the KIWD and KCMX areas early on in the forecast period, with resulting reductions in ceilings and visibilities. There is a potential for low-end IFR conditions at both sites, but the higher probability remains at KCMX and have brought in IFR with the convection this evening. Both sites will see IFR ceilings/visibilities overnight as stratus/fog develops behind the front. Expect periods of LIFR at KCMX thanks in good part to developing upslope flow there. KSAW is more problematic as more mid/upper-level energy rides up to the north, but enough in the area to warrant VCTS and then VCSH there. KSAW will also see IFR ceilings and a little fog late overnight. Have kept mention of LLWS at KSAW this forecast, thanks to expected development of LLJ this evening. Things improve as drier air works into the region in the latter part of the forecast with VFR conditions returning to KIWD and KCMX during the early daylight hours, and a little later in the day at KSAW. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 439 PM EDT FRI SEP 25 2020 A cold front approaching from the west and low level jet out ahead of it will lead to breezy south winds tonight on the east half of the lake. There could be a brief window around 9 pm to midnight where the elevated platforms gust to gale force, but it will be short-lived. There will likely be thunderstorms with the cold front moving west to east across the lake this evening, and they could be strong with hail and gusty winds. Behind the front, rain falling over the lake plus high dew points will likely generate areas of dense fog, especially over the west half. That fog will mix out somewhat tomorrow but patches of it will continue to drift around the lake through the day with lighter southerly winds. Sat night, a fast moving developing/strengthening low pres will lift ne across Lake Superior or Upper MI. Since there is uncertainty on the track, wind response is also uncertain. If the low tracks across western Lake Superior, winds will ramp up with gusts probably to 25-30kt later Sat night into Sun as is currently in the fcst. Could even be be a brief period of gales. If the low tracks farther s, winds will end up lighter. Colder air will flow into the Great Lakes region during next week. With unstable conditions developing over the lake, winds will likely be into the 15-25kt range at times thru at least the first half of the week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement through Saturday morning for MIZ014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...RJC LONG TERM...Rolfson AVIATION...RJT MARINE...RJC/Rolfson
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 323 PM CDT Fri Sep 25 2020 Current temperatures are generally in the 80s with 90 popping up in a few select locations. A swath of wildfire smoke is draped over the I-80 area now. The HRRR suggests the bulk of it at 4-7km, though discerning noses may catch a whiff here at the surface. It may lead to falling shy of forecast maxes. Zonal flow over the northern plains will drag weak boundaries over the area over the next few days, producing occasionally flip-flopping wind fields. A dramatic pattern change brings a round of fall weather next week. TONIGHT AND SATURDAY... A weak cold front is sweeping in from the northwest. Surface analysis shows it between Tekamah and Omaha with a lack of wind suggesting its presence near Fremont. As the front continues southeast this evening, it`s washing out with most of the CAA remaining in eastern South Dakota. Southerly winds redevelop by sunrise Saturday morning in response to another approaching shortwave. Model guidance suggests similar max Ts across the CWA but with a reduction in overhead wildfire smoke, we may see more locations manage 92F, with records (mid- 90s) possibly met or tied. SUNDAY AND NEXT WEEK... Broad cyclonic flow develops over the eastern 2/3 of the CONUS behind a significant September cold front. Guidance remains hazy as to when the front will pass on Sunday and temperatures will hinge on that timing. Have opted to stick with NBM`s Sunday afternoon / evening passage time. This allows highs to peak near 70, but there`s plenty of wiggle room in the models. Sunday evening will be breezy with gusts of 30mph plus. Scattered POPs still reasonable along the front... am not expecting thunder. QPF of under half an inch doesn`t excite. Isolated showers are possible but improbable in the disturbed cyclonic flow, but chances better south and east and I`ve kept forecast dry for next week. Expect winds to be breezy each afternoon. Have mentioned chance of frost/freeze by week`s end. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 612 PM CDT Fri Sep 25 2020 VFR conditions will continue through the period. Winds will generally become light and variable this evening before turning to the south tonight. Gusts up to 20-25 kts will be possible by Saturday afternoon, as winds continue to veer to the WNW. Speeds are expected to diminish near the end of the TAF period, around 00Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Nicolaisen AVIATION...KG
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
846 PM MDT Fri Sep 25 2020 .UPDATE... Issued at 846 PM MDT Fri Sep 25 2020 No major changes this evening as fcst, including Red Flag Warning/Wind Advisory tomorrow, remains on track. Did make some minor adjustments to winds tomorrow, nudging highest winds and gusts down for much of w cntrl SD. Dense mid-upper cloud cover may limit mixing somewhat, especially over the srn half of the area, and most guidance suggests that BL winds of 30+ kt will largely be north of a KGCC-KD07 line. Strongest winds/gusts across w cntrl SD will likely occur late AM/early PM with front and associated pressure rises, while strongest winds elsewhere will likely be in the early-mid aftn as mixing allows for maximum momentum transfer. && .DISCUSSION...(This Evening Through Friday) Issued at 120 PM MDT Fri Sep 25 2020 Water vapor shows broad trof over the northwest/north central CONUS. At the surface, high is centered over the Black Hills with deepening lee trof along the northern Rocky Mountain Front. A pleasant early afternoon across the area with temps generally in the 70s and some high clouds streaming overhead. Cold front will move into the region late tonight as upper low takes shape over southern SASK. Could be a couple -shra late tonight and early Saturday with fropa, but little moisture to work with. Trof deepens over the Northern Plains on Saturday, with deep mixing by afternoon tapping into the 35-45kts of 800-700mb layer winds. GFS as well as several higher res models including the ARW and HRRR mixing very dry air to the surface, with minimum RH near or possibly below 20%. Given the very dry fuels and lack of recent precip, will issue a Red Flag Warning for the plains locations of far northeast WY and northwest/west central SD. Will also hoist a wind advisory for the usual windy areas of northwest and west central SD. Secondary upper trof rotates through on Sunday, with another round of strong winds into advisory and possibly warning range. A bit more moisture to work with, so a better chance for -shra along with some higher elevation snow. Given the expected cooler temps and higher relative humidity, Red Flag conditions will be less likely. Deep upper trof sets up over the eastern CONUS for much of next week with upper ridge along the west coast. Periodic dry cold fronts with gusty northwest winds will lead to elevated fire weather conditions. Temps will be near to slightly below average. && .AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening) Issued At 523 PM MDT Fri Sep 25 2020 VFR conds will continue through the period. Breezy NW winds will develop behind a front late tomorrow morning through the aftn across much of the area, with strongest winds and gusts across the wrn/nwrn SD plains. A few SHRA cannot be ruled out tomorrow AM/aftn over nern WY/nwrn SD/the nrn Black Hills behind the front. && .FIRE WEATHER... Issued at 120 PM MDT Fri Sep 25 2020 A cold front will move through late tonight, with strong northwest winds developing on Saturday. Given the very dry air in place, Red Flag conditions are expected to develop across the plains of far northeast WY and northwest through west-central SD. Any fire starts on the plains, especially in the Red Flag Warning area, will have the potential to spread very rapidly due to the dry fuels/drought and strong winds. Another round of very strong northwest winds are expected Sunday, but temps should be cooler and relative humidity slightly higher. Elevated fire weather conditions are expected, but Red Flag conditions are not looking likely at this time. Periodic dry cold fronts with gusty northwest winds will lead to elevated fire weather conditions for most of next week. Temps will be near to slightly below average. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Red Flag Warning from noon to 8 PM MDT Saturday for SDZ323-324- 327>331. Wind Advisory from 10 AM to 8 PM MDT Saturday for SDZ001-002- 012>014-025-026-031-032-072-073. WY...Red Flag Warning from noon to 8 PM MDT Saturday for WYZ314-316. && $$ Update...Sherburn DISCUSSION...Johnson AVIATION...Sherburn FIRE WEATHER...Johnson
Area Forecast Discussion
National Weather Service Las Vegas NV
1252 PM PDT Fri Sep 25 2020 .SYNOPSIS...Warm and dry conditions will continue the next couple of days before a cold front drops into the region Monday bringing a round of northerly winds and a day of near normal temperatures. High pressure will quickly rebuild next week with temperatures rebounding several degrees above normal Tuesday through Friday. && .DISCUSSION...through next Friday. Conditions so far this afternoon have closely mirrored Thursday afternoon, with thick smoke again plaguing the Owens Valley and breezy southwest winds picking up across Northwest Arizona. Southwesterly breezes will increase to encompass much of southern Nevada and Northwest Arizona by late this afternoon, though will remain below wind advisory or red flag thresholds. Meanwhile, the HRRR suggests some slight improvement in surface visibility across the Owens Valley, though given a modest capping inversion near the ridgetop level and general persistence of thick smoke, I`m skeptical of any substancial improvement. Similar conditions are in store for Saturday and most of Sunday before some changes creep in from the north. Winds will shift around to the north as early as Sunday morning with a push of stronger winds arriving Sunday evening as the gradient across the Intermountain West tightens as a trough digs into the High Plains. Gusty winds will overspread much of Southern Nevada and lower Colorado River Valley with gusts of 30-40 mph possible overnight. Winds will gradually decrease Monday afternoon but the combination of wind, dry air, and dry fuels may prompt some enhanced fire danger concerns. In addition, cold advection behind the cold front will suppress high temperatures Monday to near late September normals. The respite from the heat will be brief however as an expansive and high amplitude ridge rebuilds across the Western US. High temperatures will climb back several degrees above normal Tuesday through Friday, with dry conditions persisting. && .FIRE WEATHER...A cold front will move into the region on Sunday evening with northerly winds quickly filling in behind it. Dry fuels, marginal RH recoveries, and wind gusts to near 35 mph will be possible especially across Southern Nevada and the lower Colorado River Valley. RH will decrease further on Monday afternoon as wind speeds gradually relax. A Red Flag issuance may become necessary as early as tomorrow for the late Sunday-Monday time frame. && .AVIATION...For McCarran...Light easterly winds will become south- southwesterly this afternoon, with confidence increasing of the switch around 21Z. Gusts should remain generally between 12 and 18 kts, but an isolated gust to 20 kts is not out of the question. Gusts will become less likely after sunset, but winds will remain elevated around 10 kts through much of the overnight period before becoming light and variable during the early morning hours. A similar set up expected Saturday, with lesser confidence in timing and speed of the southerly wind push. Reduced visibility possible through the TAF period, with lingering wildfire smoke. For the rest of southern Nevada, northwest Arizona and southeast California...South-southwesterly winds will increase this afternoon with occasional gusts to 20 kts expected, before dying off after sunset. Winds will trend more southerly along the Colorado River Valley and westerly at KDAG. Similar conditions expected Saturday. Reduced visibility possible through the TAF period due to lingering wildfire smoke, particularly in the Owens Valley. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Outler AVIATION...Varian For more forecast information...see us on our webpage: or follow us on Facebook and Twitter