Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/13/21

Area Forecast Discussion
National Weather Service Denver/Boulder CO
600 PM MDT Tue Oct 12 2021 .UPDATE... Issued at 553 PM MDT Tue Oct 12 2021 Strong winds expected along the the Wyoming/Nebraska border Wednesday morning. HRRR indicating wind gusts to 60 mph at least through the morning and into early afternoon. Therefore a High Wind Warning had been issued for northeast Weld, Logan, Phillips and Sedgwick counties from 6 AM to 6 PM Wednesday. && .SHORT TERM...(This evening through Wednesday) Issued at 245 PM MDT Tue Oct 12 2021 The center of upper low is currently over southwestern Utah. There is some convection breaking out over the forecast area this afternoon. The snowfall was slow to get going over the high mountains through today. In the lower levels there is an elongated circulation just east of Fort Morgan to south central Elbert County. The best convection is firing just to the east of this. Winds over the eastern plains are south and southeasterly from 20 to 40 knots. Models show the upper low center to track into the far southwest corner of Nebraska by 06Z tonight. After that, west-southwesterly flow aloft will increase over the CWA overnight into Wednesday morning. There looks to be enough moisture to keep widespread pops going in the mountains and foothills with scattered coverage over the plains through around midnight tonight. Will leave the snow advisory going in Zones 31 and 33 through 12Z Wednesday morning with enough moisture lingering along with orographic help. For winds, will leave the High Wind Warning going over the Palmer Ridge through 6 PM this evening. Will up the High Wind Watch to a Warning over the northern foothills from 06Z to 18Z based on the a decent mountain top stable layer, strong subsidence and a pretty strong low level pressure gradient expected. For temperatures, Wednesday`s highs will be close to today`s readings. .LONG TERM...(Wednesday night through Tuesday) Issued at 223 PM MDT Tue Oct 12 2021 A quick moving system Thursday-Friday will bring another round of snowfall for the mountains/foothills, Palmer Divide and perhaps a few flakes further east for the Urban Corridor. Amounts for the mountains will likely be lighter (couple inches) than the previous system. Thursday through Thursday night... There is good agreement among model guidance that trough will push into the region Thursday into Thursday evening. Moisture will be fairly limited; however, QG fields indicate an area of weaker ascent which should support another round of light to moderate snowfall for the mountains. The Foothills also display potential for light snowfall with even a chance for the Urban Corridor still being advertised by some model solutions. As the trough pushes east into the area Thursday, precip. chances increase towards the afternoon and spread eastward into the evening hours. There is a signal for a few inches of snowfall over the Palmer Divide supported by upslope component flow. There is more uncertainty in regards to snowfall potential for the plains/I-25 corridor. Models are consistent with cool air advecting in given northerly component flow and snow levels will resultantly drop through Thursday evening. However, there is disagreement among model guidance with respect to the amount of cooling. Wet bulb freezing level heights vary from model to model with some solutions being too warm to support snowfall. Ensembles continue to display a split in members for snowfall in the Urban Corridor. Overall, there is sufficient confidence for snowfall over the higher elevations into the Foothills overnight Thursday while potential remains for light snow along the Urban Corridor. Friday through early next week... Cool, below normal temperatures continue Friday with NW flow aloft. Although winds won`t favor the optimal cross-barrier flow for strong downslope winds, could see increased winds with gusts to 30 mph over portions of the mountains/foothills. Ridging builds in Saturday which initiate a warming trend and dry conditions. By Sunday, temperatures rebound to 60s and low 70s across the plains. Less confidence in the pattern next week as there is a spread in solutions among deterministic and ensemble guidance. No major signal for active weather and temperatures continue to trend slightly above normal. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 523 PM MDT Tue Oct 12 2021 VFR conditions will continue through 05Z. Rain showers will keep the environment humid enough to bring down visibility levels to MVFR conditions starting 05Z to 08Z at KDEN and KBJC. BKN skies will prevail through 09Z clearing to SCT or FEW Wednesday morning. A wind boundary may develop shown on a few short term models near 22Z at KDEN which could potentially make the wind direction and wind speeds tricky. Forecast confidence is higher in gusty westerly winds due to upper levels occurring a KAPA and KDEN through 0Z. && .BOU WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 6 AM to 6 PM MDT Wednesday for COZ042-048- 050-051. High Wind Warning until 6 PM MDT this evening for COZ041-046-047. High Wind Warning from midnight tonight to noon MDT Wednesday for COZ035. Winter Weather Advisory until 6 AM MDT Wednesday for COZ031-033. && $$ UPDATE...Cooper SHORT TERM...RJK LONG TERM....Mensch AVIATION...AD
Area Forecast Discussion
National Weather Service Dodge City KS
835 PM CDT Tue Oct 12 2021 .MESOSCALE DISCUSSION... Issued at 824 PM CDT Tue Oct 12 2021 Key Messages... Damaging winds, hail to quarter size and brief, weak tornado spinups will continue to be the primary concerns this evening unless we see the development of discrete supercells. The storm line will sweep across western Kansas and into central Kansas after midnight. Technical discussion... Convective mode has been mainly linear this evening despite the strong shear profile. It`s still possible for discrete storms to develop; but the later we get into the evening the smaller the chances. However, given the strong shear, any bows in the line could result in enhanced storm relative shear and a brief tornado spinup. But as long as convection stays linear, the primary concern will be damaging straight line winds and hail to quarter size. && .SHORT TERM...(This evening through Wednesday) Issued at 212 PM CDT Tue Oct 12 2021 ...Significant Severe Weather Tonight, Including Tornadoes... Early this afternoon, a major mid-latitude cyclone was maturing out across western Colorado. A surface low continued to rapidly deepen just lee of the Colorado Rockies, and the surface winds were responding nicely with widespread south-southeast winds in the 20 to 25 knot range with higher gusts. Rapid northward transport of 60-65F surface dewpoints were underway across the eastern Texas Panhandle into west central Oklahoma. Everything that was discussed in yesterday afternoon`s Short Term discussion remains valid as of this forecast update. A significant severe weather event is about to unfold later on this evening. The only thing that has really changed, and has become increasingly concerning, is that the low level moisture (62-65F dewpoints) will be making a run on southwest Kansas a little bit quicker than previously forecast...and a bit farther west...such that areas along and event a bit west of Highway 83 now have an increased risk of significant severe weather, including tornadoes. The 02-05Z (9 PM to Midnight CDT) time frame is of particular concern, as the latest HRRR and RAP low level thermodynamic and shear parameters are well into the tornado category...even significant tornado a large region will have 0-1km AGL storm-relative helicity in the 300- 400 m2/s2 during the 02-05Z time frame. This is also the best time frame for discrete supercell mode. If the storm mode remains primarily supercellular in the critical 02- 05Z time frame, we have to face the possibility of long-track significant tornadoes covering potentially 10s of miles. This is extremely unusual for far western Kansas to see tornadic storms racing northeast at 50+ mph, but this is exactly what we may be dealing with tonight. This puts much more land at risk, obviously, with such fast storm motions. This will also present a challenge for warning forecasters tonight given such fast, forward storm (tornado) motion. Eventually, the primary severe weather mode will become more linear in nature as the risk shifts east by/shortly after midnight. All in all, a dangerous night of severe storms is still on track for much of the southwest Kansas region. .LONG TERM...(Wednesday night through Tuesday) Issued at 346 PM CDT Tue Oct 12 2021 The next storm system slated to impact the region will move across late Thursday into early Friday, however the surface front is expected to remain just south of the DDC forecast area, so the severe weather potential will remain south and east of southwest Kansas. That said, we will need to watch our far southeast CWA (mainly Barber County) as a surface wave along the front will be pretty close to south central Kansas. We will keep some POPs in Barber county area as a result. Light cold sector precipitation is still expected across the remainder of our forecast area along the mid level frontal zone late Thursday Night, but widespread moderate or heavy rainfall is not expected. Fairly cool air behind the front will filter in on Friday, and afternoon temperatures will struggle to get out of the 50s. It still looks like there is the potential for a frost/freeze across mainly far west central Kansas. Frost/freeze headlines may be required if these model trends continue out west. A high pressure ridge in the mid/upper troposphere will move across western Kansas over the weekend with much quieter weather forecast. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 630 PM CDT Tue Oct 12 2021 Low level stratus in central and south central Kansas will continue to develop slowly northwestward into portions of southwest and west central Kansas within a prevailing southeasterly upslope flow, resulting in MVFR cigs in vicinity of KDDC, KHYS, and potentially KGCK through mid/late evening. IFR cigs cannot be ruled out at KDDC. Strong to severe thunderstorms are expected to develop along and ahead of a strong frontal boundary edging into extreme southwest Kansas generally after 01Z, then spread eastward across the remainder of southwest Kansas into central/south central Kansas through 07Z, affecting all TAF sites. The main impacts will be damaging winds, large hail, and isolated tornadoes. Prevailing southeasterly winds 15 to 30kt will continue ahead of the aformentioned approaching frontal boundary, then turn west-southwesterly around 10-20kt behind the boundary as it pushes eastward overnight. && .PRELIMINARY POINT TEMPS/POPS... DDC 44 67 42 67 / 90 0 0 10 GCK 40 65 38 63 / 80 0 0 0 EHA 42 70 39 66 / 30 0 0 0 LBL 41 69 38 68 / 60 0 0 0 HYS 46 65 40 62 / 90 0 0 10 P28 53 70 48 73 / 90 10 0 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MESOSCALE...Finch SHORT TERM...Umscheid LONG TERM...Umscheid AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
631 PM CDT Tue Oct 12 2021 .AVIATION (00Z TAFs)... VFR conditions prevail across South Central Texas this evening. A band of scattered SHRAs and isolated TSRAs will persist over the next hour or two near SSF to just east of AUS. Guidance indicates MVFR ceilings developing along the I-35 corridor and into the Hill Country 03Z-06Z, including at AUS/SAT/SSF, and eventually into portions of the Rio Grande near DRT, where possible IFR conditions may occur, 11Z-13Z. Earlier convective allowing model runs were indicating a complex of SHRAs and TSRAs developing along the Rio Grande early this evening. So far there is no indication of this taking place on radar. Latest HRRR runs have delayed this into the late evening, developing around the Rio Grande 03Z-06Z and moving through the Hill Country overnight and into early Wednesday morning. We have followed this trend with the DRT TAF. && .PREV DISCUSSION... /ISSUED 315 PM CDT Tue Oct 12 2021/ SHORT TERM (Tonight through Wednesday Night)... A very moist and moderately unstable atmosphere will remain in place through the next 48-60 hours. The primary issue then is what lifting mechanisms will be in place, when, and where. Diurnal heating has sparked isolated thunderstorms amongst widespread scattered light showers this afternoon. The storms should remain along/east of I-35, primarily over the coastal plains. Otherwise, another shortwave trough will eject from northern Mexico into west central Texas overnight. This trough and the diurnal uptrend in the low level jet should provide the lift for another round of storms to develop in Mexico, then develop/propagate into our area after midnight. Rainfall will be spotty and generally under one inch, although a few spots may receive more than one inch by daybreak Wednesday. Wednesday will feature a pattern similar to today, with light to moderate rain at many locations in the morning, then tapering off and skies partially clearing by early afternoon. Again, rainfall amounts will be generally under 1/4 inch, but a few locations could receive 1/2 to one inch by noon. The main action period will be Wednesday night into Thursday afternoon, as the remnants from Hurricane Pamela, a slow moving cold front dropping south from northwest Texas, and moist Gulf air all converge on central Texas. It is not just the near record levels of moist air, but the remnants of Pamela actually interact with the jet stream and help create upper level divergence, which induces strong lifting motion, and thus the potential for heavy rain. There is also a marginal risk for damaging winds or brief tornadoes, especially late Wednesday night/early Thursday morning, as low level shear and buoyancy may be strong enough for some storms to develop rotation. Total rainfall amounts from Wednesday morning through Thursday afternoon will average 2 to 4 inches across the area. A number of spots may receive 5-6 inches in the Hill Country, and one or two spots may receive just over 7 inches of rain near the Highland Lakes. A Flash Flood Watch is in effect from 7 am Wednesday through 7 pm Thursday for locations generally along and west of I-35/I-37. LONG TERM (Thursday through Tuesday)... The remnant low associated with Pamela is forecast to push across the northern part of South Central Texas on Thursday between 7 am and 1 pm. An upper level long wave trough axis pushing across the Intermountain West is expected to push to the southeast and east and over the Southern Plains through the period. This feature will help the remnant low to push toward eastern Texas on Thursday afternoon with dry weather conditions spreading across the area from west to east. However, locally heavy rain is still possible across part of the Hill Country through early Thursday afternoon. Can`t ruled out some areas getting one half to one inch of rainfall during this particular time frame. With that said, the Flash Flood Watch remains in effect for the Hill Country through 7 pm Thursday. As the day progresses, a drier airmass is forecast to push across the area from the west ahead of a surface trough/dry-line. A break from the rain is expected as mentioned above Thursday afternoon into the evening. Then, a cold front is forecast to push across South Central Texas on Friday morning with little moisture to work with but with some instability in place as the boundary nears the I-35 corridor. Therefore, decided to go with slight chance of showers and thunderstorms mainly along and southeast of I-35. In the wake of the cold front expect dry weather conditions mainly Friday evening through the upcoming weekend. The dry and cooler airmass will keep South Central Texas around the upper 60s across the Hill Country with 70s elsewhere. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 74 87 71 84 69 / 40 60 70 70 10 Austin Bergstrom Intl Airport 73 88 70 84 68 / 30 50 70 60 10 New Braunfels Muni Airport 73 90 71 86 68 / 30 50 70 60 10 Burnet Muni Airport 73 84 69 81 66 / 50 80 80 60 10 Del Rio Intl Airport 74 85 69 91 68 / 70 80 60 10 - Georgetown Muni Airport 72 87 70 83 68 / 40 70 80 60 10 Hondo Muni Airport 73 88 70 87 67 / 50 60 80 40 - San Marcos Muni Airport 73 89 70 86 68 / 30 50 70 60 10 La Grange - Fayette Regional 75 90 73 86 71 / 20 30 40 60 10 San Antonio Intl Airport 74 88 72 86 71 / 40 60 80 60 - Stinson Muni Airport 76 91 74 88 71 / 20 50 70 50 - && .EWX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Wednesday morning through Thursday evening for Atascosa-Bandera-Bexar-Blanco-Burnet-Comal-Dimmit-Edwards-Frio- Gillespie-Hays-Kendall-Kerr-Kinney-Llano-Maverick-Medina-Real- Travis-Uvalde-Val Verde-Williamson-Zavala. && $$ Short-Term/Aviation...76 Long-Term...04
Area Forecast Discussion
National Weather Service Goodland KS
848 PM MDT Tue Oct 12 2021 .UPDATE... Issued at 847 PM MDT Tue Oct 12 2021 Have removed all counties along Highway 25 from the Tornado Watch based on current radar trends. East of there, the Watch remains for another couple hours. && .SHORT TERM...(This evening through Wednesday night) Issued at 245 PM MDT Tue Oct 12 2021 500mb RAP analysis and satellite imagery showed a low centered over eastern Utah and western Colorado, placing the High Plains under southwest flow out ahead. This system is causing quite the variety of weather today. South to southeast winds have been sustained at approximately 25 to 45 mph, with gusts up to 60 mph observed so far. These winds have produced patchy blowing dust this afternoon, producing some slight reductions in visibility across portions of the region. At 2 PM MT, temperatures ranged in the mid 60s to mid 70s. Some cumulus clouds and showers had developed in northeastern Colorado. A severe weather event is expected to occur this afternoon and evening. Isolated thunderstorms will form in the vicinity of the Colorado border in the next couple of hours. Activity will then gradually shift to the east, increasing in coverage and intensity through the evening. Storm mode will play a large role in hazards through the event. Initially, when storms are discrete, (while damaging winds will be possible) large hail and tornadoes will be the main threats. Low level parameters as well as hodograph profiles and 0-1km helicity suggest that the timeframe that is most favorable for tornadoes is generally from sunset to a few hours afterwards. The area of most concern is east of the Colorado border, particularly south of Interstate 70. The threat of tornadoes is made even more dangerous by a potential for long-track tornadoes occurring at nighttime when they are more difficult to see. As a frontal boundary pushes eastward, discrete storms will evolve into a line of thunderstorms in the late evening. As this occurs, hazards will transition to predominantly a wind threat. Storms are anticipated to move rather quickly, minimizing the concern for flash flooding. Severe thunderstorm activity should exit to the east around midnight; however, some showers/non-severe storms may linger in the eastern zones overnight. Quiet weather is expected to return tonight behind the severe threat, with low temperatures falling into the upper 20s to low 40s (from west to east). Patchy frost will be possible in eastern Colorado early Wednesday morning. On Wednesday, our system tracks north of the region, leaving behind dry weather. Breezy northwest winds are forecast north of Interstate 70 on the backside of the low through the morning and into the afternoon hours as temperatures climb into the low to mid 60s. Relative humidities may fall as low as 18 percent in eastern Colorado in the afternoon; fortunately, the lowest values do not seem to be collocated with the higher wind gusts at this time. Southwest flow resumes aloft Wednesday night, with lows in the 30s. Overall, quiet weather is expected. Clear skies and light winds do allow for a potential of patchy frost north of Interstate 70. .LONG TERM...(Thursday through Tuesday) Issued at 324 PM MDT Tue Oct 12 2021 At the beginning of the extended period, long-term models show the CWA having a southwesterly flow aloft as the CWA is underneath the front part of an upper air trough over the western CONUS on Thursday. Going into Friday, the upper air trough moves slowly eastward with the upper air flow turning northwesterly by the evening hours as the back part of the trough moves over the CWA with a ridge moving behind it in the western CONUS. On Saturday, models show the upper air ridge moving eastward over the CWA. Going into Sunday, long term models show the ridge remaining over the CWA and then the models start to deviate from their solutions in how the upper air pattern develops behind it. The GFS has an upper air low developing over southern CA during the evening with another trough moving over the Pacific Northwest. On Monday, the GFS has the southern low moving east into AZ with the trough moving over central Canada along with a ridge moving over the western CONUS. On Tuesday, the GFS shows the CWA between the ridge in the west and the upper air trough to the east which makes its way over the Great Lakes area. As an alternate solution, the ECMWF shows a trough reaching down to northern CA behind the ridge on Sunday evening. For Monday, the ECMWF moves the trough eastward over the Rockies and starts to close off into a low. By Tuesday, the ECMWF looks to move the low over the CWA. As there is a good amount of uncertainty between long term models beginning Sunday and beyond, this situation will be monitored for better agreement in future runs. At the surface, the CWA looks to see chances for precipitation Thursday evening into Friday morning with the remainder of the long term period staying relatively dry. Chances for precipitation are expected to begin on Thursday evening west of a line from Benkelman, NE to Hoxie, KS with these chances increasing going westward. Precipitation starts as rain for a P-type across the aforementioned area with chances for snow mixing in starting during the nighttime hours along and west of the CO border. Areas in CO may see light snow showers instead of a mixed P-type overnight though snowfall amounts look to be negligible at this time. With overnight temperatures getting colder, the Tri-State area may see frost develop during the long term period. Friday, Saturday, and Monday nights look to have the best chances for frost development within the Tri-State area. At or below freezing temperatures can be expected as well along and west of the CO border on Thursday night, across most of the Tri-State area on Friday night, and Yuma county on Monday night. The Tri-State area expects daytime highs on Thursday in the lower 50s to lower 60s followed by highs on Friday being in the middle to upper 50s. The Tri-State area sees daytime highs on Saturday warming to the middle to upper 60s before highs increase to the lower to middle 70s on Sunday. Monday looks to be the warmest day in the long term period with highs in the middle to upper 70s with Tuesday`s highs expect to be in the middle 60s to lower 70s. The Tri-State area expects to see overnight lows on Thursday between the upper 20s and upper 30s while Friday sees lows ranging from the middle 20s to lower 30s. Overnight lows on Saturday look to be in the middle 30s followed by Sunday night seeing lows in the upper 30s to middle 40s. Overnight lows for the remainder of the long term expect to range between the lower 30s to the lower 40s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 529 PM MDT Tue Oct 12 2021 The passage of a strong cold front thru the region will affect both terminals at least for the first half of the forecast. For KGLD, mainly VFR ceilings with some thunderstorms, some large hail with some reduction to visibility thru about 07z Wednesday. Low ceilings around BKN-OVC040-050 will give way to SKC- SCT150-200 during this time. The frontal passage will have southeast winds currently around 25-35kts become west-southwest 15-30kts by 05z. Some reduction to 5-15kts from 05z-15z. LLWS 13z-15z 300@40kts. For KMCK, thru 05z Wednesday, ceilings will range from VFR down to IFR in thunderstorms, with some large hail. After 05z, BKN035 giving way to scattered high cloud by 12z Wednesday. Visibility in precip will range 2-5sm at worse. Winds southeast 15-30kts with gusts to 40kts thru 01z. By 05z, a shift to the west- southwest 10-15kts with gusts back up to 25kts by 12z. LLWS 03z- 05z 160@45kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JN SHORT TERM...JBH LONG TERM...MRC AVIATION...JN
Area Forecast Discussion
National Weather Service Grand Rapids MI
914 PM EDT Tue Oct 12 2021 LATEST UPDATE... Update .SYNOPSIS... Issued at 330 PM EDT Tue Oct 12 2021 -Dry, warmer Wednesday but considerable clouds -Showers/storms Wednesday night into Thursday morning -More rain Friday into Saturday, turning cool/breezy && .UPDATE... Issued at 914 PM EDT Tue Oct 12 2021 Minimal changes this evening. Will keep low chances for drizzle going through the night mainly north of I-94. Models are pointing to an occasional saturated and weakly unstable layer between 1000 ft and the cap at 3500 ft, with very dry air above the cap. While omega in the moist layer is departing, a slight thermal and moisture contribution from Lake Michigan and downwind zone of confluence (early hints of lake-effect banding) may be enough to keep very light precipitation going overnight. && .DISCUSSION...(This evening through next Tuesday) Issued at 330 PM EDT Tue Oct 12 2021 -Dry, warmer Wednesday but considerable clouds Sfc low over ern upr MI responsible for all the low clouds and showers today continues to fill tonight and Wednesday while moving slowly away. Low clouds and areas of light rain/drizzle will be rather slow to depart and will likely linger through at least midday Wednesday. Once the low clouds finally do break up/lift out Wednesday, considerable mid and high clouds associated with the next system will be streaming in. However renewed warm advection pattern and southerly flow ahead of that system sends high temps back up into the lower or mid 70s. -Showers/storms Wednesday night into Thursday morning Unlike the last few systems from the wrn longwave trough, which passed near or through MI, the next upper low passes well west of Michigan through the nrn Plains Region on Wednesday. That occluding system still pushes a frontal boundary in our direction, with some semblance of a triple point coming across srn lwr MI on Wednesday night. Most guidance, with the exception of the 12Z HRRR, keeps the area dry until after midnight which would keep any severe weather threat quite low. Actually the highest MUCapes may stay south of MI overnight per NAM and newer RAP guidance. Highest pops will be featured overnight into Thursday morning, with some drying arriving in the afternoon into Thursday night as the sfc frontal boundary nudges just south and east of the area. -More rain Friday into Saturday, turning cool/breezy Wrn longwave trough moves in our direction for the end of the week and a shortwave in the base that trough moves along the stalled frontal boundary just south of MI. Ensemble guidance favors the axis of heaviest QPF closer to the frontal zone from Indiana into se lwr MI, but still shows lighter rains falling across our area much of the time Friday into Friday night. Then, as cold advection sweeps in behind that shortwave on Saturday, we should see a continuation of clouds and sct`d showers with an H8 thermal trough near 0C overhead. (Lake effect should become a factor with air that cool.) High temps will be held in the 50s Saturday, before a return to sunshine on Sunday allows a recovery back into the 60s. Tight pressure gradient over the weekend keeps a breezy westerly flow over the GrtLks, so definitely a more normal fall-like pattern coming in by then. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 752 PM EDT Tue Oct 12 2021 Belts of IFR ceilings and localized MVFR to IFR visibility containing drizzle continue to stream from west to east this evening, primarily affecting MKG, GRR, and LAN. Low level moisture and pockets of rising air are shown in the models through Wednesday morning, so MVFR ceilings should prevail through then. However there may be a tendency toward scattering out to VFR at times. Drier air makes a pronounced arrival Wed afternoon, so VFR seems likely then. Showers and and lowering ceilings should move back into West Michigan Wed evening. && .MARINE... Issued at 330 PM EDT Tue Oct 12 2021 Westerly flow gradually diminishes later tonight as the sfc low to our north over upr MI continues to weaken and is replaced by high pressure. No change to the expiration time of the Small Craft Advisory at 11 PM. The next chance of higher winds and waves develops on Wednesday night due to increased southerly flow ahead of the next system, with the main concern for advisory criteria being north of Holland. After a period of weaker flow for Thursday into Friday, hazardous conditions appear likely again for the weekend - especially Saturday - as colder air arrives. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Small Craft Advisory until 11 PM EDT this evening for LMZ844>849. && $$ UPDATE...CAS SYNOPSIS...Meade DISCUSSION...Meade AVIATION...CAS MARINE...Meade
Area Forecast Discussion
National Weather Service Wilmington NC
1011 PM EDT Tue Oct 12 2021 .SYNOPSIS... High pressure continues to build into the area this evening and this week. Skies will start to clear out midweek, and temperatures will begin to warm, potentially to near record values by Friday. A cold front moves through Saturday, bringing a slight chance of showers to the area. After the front, fall returns, bringing much more seasonal temperatures to the area by the end of this weekend. && .UPDATE... No big changes necessary from the ongoing forecast with this update. Continued to raise Sky cover overnight. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... Persistent low clouds have been the big forecast story again today. A strong subsidence inversion with a base measured by 12z weather balloons at 2500 feet AGL over MHX and 3000 feet AGL over CHS has very effectively trapped low level moisture and created dense stratocumulus clouds. This morning`s 12z GFS and NAM erroneously showed the base of the inversion near 4000 feet AGL. This left too little depth of saturation for opaque clouds in the model initialization, and the rest of the model forecast quickly fell apart with sunshine and warm temperatures indicated. The inversion will continue tonight, therefore I am forecasting clouds to continue as well. Sky cover forecasts are based on a blend of the HRRR and the 90th percentile of the NBM, with some upward revisions still needed across coastal North Carolina where boundary layer dewpoints remain highest. This gives "partly cloudy" across the Pee Dee and Grand Strand region, and "mostly cloudy" near Wilmington. Forecast lows (60-65 degrees) have been adjusted up above all MOS guidance under the densest cloud cover across coastal NC. I do expect some sunshine to finally arrive Wednesday, although there may be quite a few stratocumulus clouds still dotting the sky, especially near the coast. Forecast highs (80-83) are a little below guidance consensus. It`s unclear if the inversion erodes enough Wednesday night to finally let the clouds dissipate entirely. As a hedge I`m forecasting lows a little above the clear sky MOS forecast with 60-65 degrees. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Ridging brings very warm and dry weather through this period. Thursday sees highs in the mid-to-upper 80s, with lows that night in the mid 60s. Big story focuses on Friday, when the ridge axis shifts a little to east such that is is directly overhead the Carolinas. This cranks up the heat a few degrees more from the previous day. Still looking at potentially record tying/breaking high temperatures at this point. MOS data is starting to sniff this out, and shows some of these high temperatures potentially kissing 90 on Friday. Official forecast does *not* reflect this yet, as I have capped it at 89. But with some SSE flow building in, I wouldn`t be surprised if this milestone is achieved, particularly somewhere along and north of a line from Darlington County, SC to Pender County, NC. Since there`s a greater curve in the diurnal trends on Friday, lows that night should be 2-3 degrees warmer than the previous night. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Cold front approaches from the west Saturday, quickly moving to the offshore waters by Sunday morning. The bulk of the dynamics appears to remain to the north, and this front seems to be rather moisture- starved. As a result, keeping a mostly slight chance of showers Saturday afternoon for the SC counties, with those chances moving eastward towards the coast by Saturday evening. Showers taper off overnight. Welcome fall! This cold front chops down temperatures and dewpoints alike, just in time for pumpkin carving. Expect more seasonal highs in the low-to-mid 70s Sunday through Tuesday. Lows should dip down into the low-to-mid 50s Saturday night, with the lower end of the range likely found in the SC counties. Sunday and Monday nights, with plentiful radiational cooling, wouldn`t be surprised to see lows dip down into the upper 40s in the usual cold spots in Pender and Bladen Counties. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Ceilings will linger this evening near the coast, remaining at MVFR at ILM and mainly VFR elsewhere. Clouds should gradually scatter tonight, but in general guidance continues to erode the clouds too quickly. Fog not likely tonight, with any patchy fog limited to far western areas. VFR on Wednesday with continued light northerly flow. Extended Outlook...VFR expected to dominate during the mid to late week period due to high pressure. However, patchy early morning fog/stratus could lead to MVFR/IFR ceilings/vsby. && .MARINE... Through Wednesday Night...High pressure centered across the southern Appalachians will move little through Wednesday night. Light northerly winds should continue across the Carolina coastal waters, veering northeasterly Wednesday night. Seas are currently 2 to locally 3 feet primarily in two easterly swells with 10 and 15 seconds period. Wavewatch and local NWPS models show little change anticipated over the next 36 hours. Thursday through Sunday...Variable winds at 5-10kts will be the trend Thursday and early Friday. By Friday afternoon, winds have a more southerly component, as a cold front approaches. Winds continue to veer more southwesterly by Friday night, increasing to 10-15kts by Saturday morning. The front moves offshore by Sunday morning, and winds veer northerly at 15kts, with a few gusts up to 20kts possible. Seas are tame Thursday through Saturday, with 1-2ft waves at the coast, slightly increasing to 2ft waves away from shore. By Sunday, as the cold front arrives to the waters, wind waves increase to 2-3ft seas at the coast and 3-4ft waves spotted 20nm away from shore. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...ILM UPDATE...MAS NEAR TERM...TRA SHORT TERM...IGB LONG TERM...IGB AVIATION...MAS/43 MARINE...TRA/IGB
Area Forecast Discussion
National Weather Service Marquette MI
625 PM EDT Tue Oct 12 2021 .SHORT TERM...(This evening through Wednesday) Issued at 434 PM EDT TUE OCT 12 2021 Water vapor imagery and RAP analysis show a trof over the Rockies with a well-defined, deep shortwave in the base over the 4 Corners (500mb height anomaly of 340m). Downstream, ridging is over the eastern Lower 48. In the ne flow btwn the 2 features, the vigorous shortwave that was over MO 24hrs ago has weakened and is currently over the Upper Great Lakes. This wave brought widespread rainfall to the fcst area last night and today, but the heavier rainfall (generally 1-2 inches) ended up more limited, affecting only the eastern fcst area. Sfc low pres is currently located over eastern Lake Superior btwn Caribou Island, Grand Marais and Whitefish Pt. Under northerly cyclonic flow to the w of the low this aftn, low clouds have dominated the fcst area along with some -shra/dz. Pcpn has become increasingly confined to the upslope areas of western and northern Upper MI. The weakening shortwave over the Upper Great Lakes will continue to weaken as it lifts to the ne tonight. However, with the weakening sfc low moving little, low-level cyclonic upslope n to nw flow will linger, likely resulting in continued patchy -ra/-dz and some fog across portions of the w and n thru much of the night. Weak sfc ridge axis does reach western Upper MI late in the night, and that should work to end whatever light pcpn remains there. With expectation of abundant cloud cover, opted for min temps near raw model guidance consensus, 50s F across the board, coolest w. Should clouds break anywhere, temps will fall back into the 40s. Any lingering -dz should end by 12z Wed as winds go light/vrb before becoming se in response to a strong sfc low pres lifting across the Dakotas. Waa/isentropic ascent will spread ne toward Upper MI in the aftn, but the thermal gradient and thus pres gradient on the isentropic surfaces is rather weak, leading to overall weak ascent. Bulk of model guidance appears on track delaying development of pcpn into Upper MI. Best chc would be over the w, closer to better deep layer forcing. Fcst will reflect chc pops far w late in the aftn with a dry aftn prevailing to the central and eastern fcst area. Should be quite a bit of cloud cover thru the day. Even if low clouds clear out anywhere, high and mid clouds will overspread the area during the day. Expect high temps in the low/mid 60s F across the board. .LONG TERM...(Wednesday night through Tuesday) Issued at 337 PM EDT TUE OCT 12 2021 A progressive weather pattern across the CONUS will allow for the active weather pattern to continue for the Great Lakes. Temperatures will be on somewhat of a roller coaster, which is typical for Upper Michigan in the fall as multiple waves of warm and cool air will swing across the cwa in the extended forecast. Above average temperatures will quickly change to seasonal temperatures for autumn by the end of the week, and then beginning to rise to slightly above average readings once again to start next week. Due to the progressive nature of the weather systems moving through the Great Lakes, precipitation is not expected to heavy with any of the weather disturbances. On Wednesday night, the strong surface low will continue its trek to the north from the Dakotas toward Manitoba. The warm conveyor belt of moisture will propagate northward from the Gulf of Mexico, ahead of the surface cold front. Instability looks to be marginal for organized convection as the rain showers move to the northeast quickly across Upper Michigan. The GFS and Euro model show the nose of a strong 110+ knot jet streak making its way over Upper Michigan overnight, so we can expect gusty winds to be present as the system moves through the area at the surface. It will be a mild and muggy night for several areas as dew point values will remain in the 50s to lower 60s ahead of the approaching surface cold front from the west. Rain showers should push through the area by Thursday morning. The cold front will move from west to east quickly on Thursday. 850mb temperatures in the single digits will mix down to the surface with the help of the breezy winds at times, making temperatures fall behind the front quickly. Ultimately, seasonal temperatures will have arrived for this time of October across Upper Michigan by Thursday evening. The CAA behind the front, and dry air will cause sky cover to decrease Thursday on a temporary basis. Surface temperatures will quickly decrease after sunset to the 40s across the interior. The next shortwave trough riding along the upper level flow/ULL over the Canadian Provinces will propagate toward Upper Michigan late Thursday night into Friday. This will usher in another round of cloud cover from the west, and help limit overnight lows to around 40 degrees across the interior west. Throughout the remainder of Friday, the upper level shortwave will propagate to the east, and another surface frontal passage will occur, reinforcing the cooler air across the UP. This will cause the west half to struggle to reach the lower 50s for a high temperatures by late afternoon on Friday when combined with the cloud cover. Friday night through Sunday, the ULL will slowly propagate toward James Bay. Multiple embedded shortwave disturbances will propagate along the upper level northwest flow. Lake effect rain showers look plausible via nw flow at the surface through the weekend. Seasonal temperatures will remain across the area as well. 850mb between +2C to -2C will assist with lake enhanced initiation of precipitation during the weekend, thus cloud cover will assist with keeping temperatures cool. Early next week, upper level ridging will amplify across the Northern Plains, and bring warmer temperatures back to Upper Michigan. Afternoon highs will creep back up toward the upper 50s to middle 60s, which is about 10-15 degrees above normal. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 625 PM EDT TUE OCT 12 2021 Abundant low-level moisture will result in LIFR conditions prevailing at SAW until late Wed morning when improvement to low MVFR is expected. LIFR conditions at IWD/CMX will continue. Both terminals will improve to MVFR near the end of the fcst period. All terminals will see some periods -dz/-shra at least into the evening hrs. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 434 PM EDT TUE OCT 12 2021 Thru Wed morning, sfc low pres over eastern Lake Superior will meander, weaken and eventually dissipate. W of the weakening low, expect a corridor of northerly winds gusting to 20-25kt across a swath of central Lake Superior thru this evening. Winds will fall off blo 20kt by daybreak Wed. Winds will then begin to ramp up on Wed aftn, particularly over western Lake Superior, as strong low pres lifts n thru the Dakotas. Expect easterly winds gusting to 30kt by late aftn over western Lake Superior. Could be some gale force gusts to 35kt for a few hrs over the far w late aftn/early evening. SE winds will increase to 20-30kt across eastern Lake Superior Wed night. At high obs platforms, there could be some gale gusts to 35kt for a time. Front associated with the low pres will sweep across Lake Superior late Wed night/Thu morning, bringing a wind shift to the sw. These sw winds will gust to 20-30kt, strongest over western Lake Superior where there could be a few gale force gusts to 35kt. As a more seasonal air mass arrives over the Upper Lakes into the weekend, winds will likely frequently gust to 25-30kt. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...BW AVIATION...07 MARINE...Rolfson
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 313 PM CDT Tue Oct 12 2021 .Forecast Summary: Showers and thunderstorms developing tonight with some risk for damaging winds and large hail. Breezy to windy on Wednesday. Trending cooler through Friday. Warmer daytime temperatures this weekend into early next week. Potential for freezing temperatures on Friday night into Saturday morning. .Tonight and Wednesday: An intense mid/upper-level low situated along the UT-CO border as of early afternoon is forecast to undergo further intensification while developing into western parts of NE and SD by 12z Wednesday. Meanwhile, an attendant shortwave trough and accompanying 90-100 kt jet streak at 500 mb are expected to pivot through the southeast periphery of the parent low, and across the mid MO Valley on Wednesday morning. At the surface, a deepening lee cyclone over eastern CO will develop through western NE tonight and into central SD by 18z Wednesday with a trailing cold front sweeping east through our area on Wednesday morning. The vigorous, synoptic cyclone that moved through the Great Plains on Sunday and Monday shunted substantive, low-level moisture to the TX coastal plain. That moisture is now in the process of being advected poleward along a 40+ kt LLJ, which extends from central TX through western parts of KS and NE, per plan-view WSR-88D VWP observations. How rapidly that moisture returns north through the central Plains tonight will largely dictate the magnitude of severe-weather threat across our area. Latest CAM solutions remain relatively consistent in suggesting that initial, surface-based storm development will occur later this afternoon into evening over the central High Plains with that activity subsequently growing upscale into a QLCS while tracking into central NE/KS by around midnight. Thereafter, the models indicate a warm-advection-related cluster of thunderstorms developing over portions of eastern NE ahead of the QLCS, which is projected to weaken while moving through our area in the 2-6 AM time frame. Finally, the models also hint at the potential for a secondary, broken band of showers and storms forming along the cold front moving through eastern NE in the 7-9 AM time frame with all convection moving out of the area by 10 or 11 AM. In regard to the pre-storm environment, the models suggest that warming and moistening along a 50+ kt LLJ and atop a stable, near- surface inversion will contribute to a corridor of moderate instability (i.e., MUCAPE of 1000-1500 J/kg). The initial, warm- advection storms are expected to develop in that thermodynamic environment, which should support a few strong updrafts capable of hail approaching one-inch in diameter. HRRR forecast soundings suggest that the near-surface inversion will likely be maintained ahead of the QLCS, which is expected to limit the potential for an organized, damaging-wind threat. Nonetheless, any stronger, longer-lived downdrafts may be sufficient to promote sporadic pockets of 50-60 mph wind gusts at ground level. Finally, there is some suggestion that parcels may become close to surface-based along and just ahead of any showers and thunderstorms that may form along the cold front on Wednesday morning. Here too, locally strong wind gusts appear to be the primary hazard owing to the high-momentum flow field just above the ground. Steepening, low-level lapse rates coupled with a tight pressure gradient on the south side of the surface low over central SD are expected to foster breezy to windy conditions from late Wednesday morning into afternoon. Wind gusts of 35 to 40 mph appear possible, especially across northeast NE. High temperatures will range from around 60 northwest to lower 70s in far southeast NE and southwest IA. .Thursday and Friday: Another mid-level trough is forecast to amplify over the High Plains on Thursday with that feature tracking east through the remainder of the Great Plains on Thursday night and Friday. The primary surface baroclinic zone is forecast to reside well to the south of our area from the Ozarks into southern Plains. And that is where the majority of precipitation is expected to fall. The northern extent of that precipitation shield could extend north into portions of southeast NE and southwest IA on Thursday night, where we will indicate chance PoPs. Highs in the upper 50s to upper 60s on Thursday will fall back into the 50s areawide on Friday. .Saturday through Monday: Latest model data indicate an increased potential for freezing temperatures at preferred locations in northeast NE and west- central IA late Friday night into Saturday morning. Widespread frost appears probable elsewhere in our area. Lows on Sunday morning are expected to be a bit warmer, but areas of frost still appear possible. Otherwise, mid-level heights are expected to build ahead of the next trough evolving over the western U.S., which will translate to warming high temperatures through the weekend into early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 617 PM CDT Tue Oct 12 2021 Deteriorating conditions are expected later tonight ahead of a storm system moving into the region. Should see conditions drop to MVFR towards 06Z with increase of areal coverage of TSRA. Models do show some signal for small hail accompanying a few storms passing through KOMA/KLNK sometime between 07z-09z mainly affecting. However, did not include in latest TAFs given low confidence. Expect TSRA activity to eventually push east of the terminals toward 14z with VFR conditions prevailing the remainder of the period. Also, LLWS threat will be in play late this evening through early Wednesday morning at all terminals. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Mead AVIATION...DEE