Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/18/22


Area Forecast Discussion
National Weather Service Corpus Christi TX
329 PM CST Mon Jan 17 2022 .SHORT TERM (Tonight through Tuesday Night)... Tonight will be approximately 10-15 degrees warmer than last night in response to a strengthening southerly flow. Shallow moisture is also expected to advect northward tonight. Models prog an embedded short wave to track across S TX overnight in an increasingly zonal flow aloft. In spite of the short wave, the moisture will remain too limited and shallow for any precipitation. A couple of models did prog very isolated weak showers over the waters where the moisture will be a tad deeper, thus kept 5 PoPs along the coast. With the shallow moisture advecting northward, the possibility of light patchy fog increases toward early Tue morning. The SREF and NAM show fog advecting northward across the Rio Grande Plains, while the HRRR shows fog developing across the Victoria Crossroads. Have included a mention of patchy fog for all inland locations briefly Tue morning. Visibilities are expected to be 5SM or higher. The chance for areas of thicker fog and lower visibilities increases Tuesday night as the low level moisture continues to advect across S TX while the mid/upper levels remain fairly dry. The caveat for Tue night, however, will be a strengthening LLJ up to 30 knots and increasing cloud cover which could hinder fog development. During the day Tuesday, more clouds and warmer temps can be expected. Highs around 80 are forecast across the western 2/3rd of the CWA. Southerly winds will also strengthen with breezy conditions expected by Tuesday afternoon across the Coastal Bend. This is in response to a deepening surface low moving eastward across the TX Panhandle and tightening the pressure gradient along the TX coast. && .LONG TERM (Wednesday through Monday)... A very warm day will be in store on Wednesday as a pre-frontal trough moves into the area. Temperatures will be well above normal in the low to mid 80s as surface winds turn to southwest over the coastal plains and northwest over the Brush Country. A strong cold front will be surging down the plains Wednesday as an upper trough dives into the upper Midwest. The cold front is expected to reach the northern counties Wednesday evening and be offshore before daybreak Thursday. Rain chances will be limited to along the coast with the front Wednesday night. A short wave trough over southern Arizona/New Mexico Wednesday night will move southeast into southwest Texas/northern Mexico Thursday. Expect areas of light rain will develop Thursday as isentropic lift increases over south Texas. Cloud cover and precipitation will lead to a colder day with highs in the 40s Thursday. The fun part of the forecast occurs Thursday night into Friday. There are some slight discrepancies between the medium range models on the timing of the short wave trough moving across the region during this period. ECM was the most progressive with the trough east of the area by Friday morning, while the GFS holds some energy back that does not move through until Friday evening. CAN and ICON are in between. This also affects the timing of when the deeper cold air reaches south Texas. NBM continues to show conditional probabilities of snow increasing late Thursday night into Friday morning over the Brush Country into the inland coastal plains. Some of the ensemble members of the GEFS show low probabilities for frozen precipitation also. However, GFS/ECM show a deep warm layer even over the Brush Country. Reluctant to mention a change over to snow at this time. But will show the possibility of light freezing rain across the northern counties as surface temperatures fall to around freezing early Friday morning. Expect rain chances will diminish from west to east on Friday as the short wave trough moves through. Expect cold and dry conditions for Friday night. Could see wind chill readings around 20 degrees over the Victoria Crossroads, northern Coastal Bend and northern Brush Country Friday night with low temperatures in the upper 20s. It will be slightly warmer on Saturday. Another short wave trough diving through the Rockies Friday will become a cutoff low over the northwest Mexico Saturday. The upper low will move east across northern Mexico Sunday leading to another chance for rain over the region Sunday into Sunday night. && .MARINE... A weak southerly flow this evening will strengthen to moderate levels overnight. The southerly flow will gradually strengthen throughout the day Tuesday, becoming moderate to strong by late afternoon and continuing Tuesday night with advisory conditions possible. This is in response to deepening low pressure across the Texas Panhandle. A moderate onshore flow/SCEC conditions will continue over the Gulf waters Wednesday, then weaken Wednesday evening as a cold front moves into south Texas. The cold front will move into the Gulf waters by early Thursday morning. A strong offshore flow will occur behind the front with SCA conditions persisting from Thursday through Friday. Gusts may reach gale force over the offshore waters Thursday night. Scattered showers and a few storms will be possible ahead of the front Wednesday night, then areas of light rain are expected Thursday through Friday. The offshore flow will weaken to moderate by Saturday with rain chances decreasing. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 50 76 60 83 44 / 0 10 10 0 20 Victoria 46 75 59 80 40 / 0 0 0 0 10 Laredo 47 80 56 84 45 / 0 0 0 0 10 Alice 45 80 57 86 42 / 0 10 10 0 10 Rockport 56 72 63 78 44 / 0 10 10 0 20 Cotulla 45 81 54 81 42 / 0 0 0 0 0 Kingsville 47 79 58 85 45 / 0 10 10 0 20 Navy Corpus 59 71 66 78 47 / 0 10 10 0 20 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ TE/81...SHORT TERM TMT/89...LONG TERM
Area Forecast Discussion
National Weather Service Cheyenne WY
448 PM MST Mon Jan 17 2022 .SHORT TERM...(This evening through Tuesday) Issued at 200 PM MST Mon Jan 17 2022 Gusty winds will remain the primary weather threat early in the short-term period. Fast gradient flow over southeast Wyoming is currently resulting in gusts in the low to mid 50mph range across the northern Snowy Range foothills. The expectation is for this faster flow to increase and translate eastward through the afternoon, affecting the southern Laramie range as well. As the gradient relaxes and faster flow aloft shifts eastward, winds at the surface should drop back below high warning criteria around sunset, when the current High Wind Warnings are set to expire. Overnight lows will run slightly above average across Wyoming and western Nebraska as cloud cover and breezy flow remain in place. A secondary maximum in surface wind flow is likely on Tuesday afternoon as a frontal system approaches from the northwest. Local wind guidance does not support wind increasing enough to necessitate any high wind headlines, however gusts in the 35-45 mph range are likely for much of the southern Laramie range and I-25 corridor on Tuesday. Mild temperatures will continue, with favorable downslope flow resulting in highs around 5-10 degrees above average. Clouds will thicken as our next system approaches from the north, however dry subcloud layers will keep any precipitation at bay until after dark on Tuesday evening. .LONG TERM...(Tuesday night through Monday) Issued at 200 PM MST Mon Jan 17 2022 Forecast guidance has trended slightly upward with both chances of precipitation as well as precipitation amounts for our next storm system. This event will arrive in the form of a cold front on Tuesday evening and overnight. Light snow with perhaps some light rain on the front end is expected on Tuesday evening, mainly over the Nebraska panhandle and far eastern Wyoming. Some forecast guidance, most notably the HRRR does depict a brief window for some freezing drizzle early in the event on Tuesday evening, assuming a warm nose above the surface front/cold pool can remain in place. However, most guidance members now eradicate any form of warm nose aloft on Tuesday evening as of the 12z guidance cycle. Any mixed precipitation will quickly change to light snow on Tuesday night into Wednesday morning as cold air at all layers pours southward behind the frontal boundary. QPF forecasts have trended upward across the board, with the HRRR leading the way showing around 0.1 to nearly 0.25" of liquid, mainly focused on the Sioux/Dawes County and Pine Ridge areas, as well as the higher elevations south of the Platte River. Other high-res guidance is in the same ballpark, and confidence is growing in a 1-2" event over much of the Nebraska Panhandle on Tuesday night ending Wednesday morning. Southeast Wyoming is a less certain forecast, as most guidance keeps the corridor of better moisture east of I-25. Still, a coating to a half inch or so remains possible for Torrington, Cheyenne, Scottsbluff and the I-80 summit before things come to an end late-morning on Wednesday. A dry stretch featuring below-average temperatures will follow from Wednesday afternoon through Friday morning as northwest flow remains in place. The next major weather system will arrive in southeast Wyoming on Friday morning. Differences in timing between the faster GFS and slower ECMWF/CMC/NAM become evident by this time and forecast confidence decreases. What is certain is that another shot of cold air is in the works as a strong front pushes southward on Friday afternoon. Snow is likely in the mountains, and perhaps in the high plains east of I-25. However, surface flow does not favor a very long period of upslope over the plains and moisture quickly translates eastward by Friday night/Saturday morning. Ensemble guidance also supports this idea, with the mountains heavily favored in this event and the plains east of I-25 seeing a model average of 0.1" of liquid or less by Saturday morning. Below-average temperatures will continue on Saturday afternoon behind the front, with warming trend with dry weather likely by the end of the weekend. && .AVIATION...(For the 00Z TAFS through Tuesday afternoon) Issued at 448 PM MST Mon Jan 17 2022 Quiet weather expected with low impacts to Aviation. Any mountain wave activity looks to be brief and confined close to the mountains tonight with low chances of any LLWS above 30 knots. SCT-BKN clouds expected above 15,000 to 20,000 feet AGL through 18z Tuesday. HAZARDS/WEATHER TRENDS: VFR conditions with winds gusts of 30 knots early this evening rapidly diminishing after sunset. && .FIRE WEATHER... Issued at 200 AM MST Mon Jan 17 2022 A ridge of high pressure to the west will maintain a dry northwest flow aloft into Tuesday. Strong and gusty west to southwest winds will prevail along and west of the Laramie Range today. Minimum relative humidities will remain at or above 25 percent. A strong cold front arrives Tuesday night, bringing much colder temperatures and chances for light snow through Wednesday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MAC LONG TERM...MAC AVIATION...TJT FIRE WEATHER...MAJ
Area Forecast Discussion
National Weather Service Des Moines IA
528 PM CST Mon Jan 17 2022 ...Updated for the 00z Aviation Discussion... .DISCUSSION.../Tonight through Monday/ Issued at 310 PM CST Mon Jan 17 2022 Primary messaging highlights: * Fog expected central and especially north overnight * Warmer tomorrow, then turning bitter cold Tue Night into early Fri * A few potential precip windows starting late this week, but mainly dry There has been little change in forecast expectations since this time yesterday with Iowa staying in northwest flow to varied degrees, including several short waves reinforcing the eastern CONUS long wave trough. This will keep our weather regime mainly dry with an extended period of below normal temperatures. Heading into this evening conditions are near seasonal normals however with patchy mid level cloudiness and areas of lingering stratus east. The 20z surface analysis notes a ridge across eastern sections, aligned with the back edge of the departing stratus, with a downslope warm front/trough along the MO River. The trough component won`t advance much, but a subtle warm front will advance into Iowa late this evening. Areas of fog are expected to develop along and ahead of this feature as it advances north into tomorrow, possibly dense at times, leading into one last warm day Tuesday before the bottom drops out later in the day. Short waves are expected to cross the Canadian provinces with low pressure tracking across the northern Plains into the Great Lakes, and an accompanying strong cold front through Iowa during the early evening hours. This will usher in gusty northwest winds and possibly some shallow blowing snow north (streamers across roads) in the stronger gusts into early Wednesday. After this bitter cold will be the main weather story Wed into Fri morning with several periods of Wind Chill Advisories possible across the north half of the state. Lows should be well below zero Wed and Thu Nights with highs no better than +/- zero north and the single digits south Thu. Some minor temperature moderation is anticipated by Friday and Friday Night as return flow strengthens, but still staying normal or just below. This will start several weak cold front or low pressure system cycles into early next week keeping our forecast just below normal and potentially introducing some minor precip chances, with ensemble guidance and the NBM mainly suggesting Friday north and possibly Monday. Confidence is low however with models not showing great consensus with timing, track, and strength of any forcing windows. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 528 PM CST Mon Jan 17 2022 Main concern will be fog potential over northern areas KFOD, KMCW, and KALO as warm air advances northeast into overnight. HRRR has been consistent in developing lower cigs/br/fog across the north mainly right along the warm front edging into western Iowa at 22z. Some uncertainty with increasing thickness overnight which may offset some of the fog potential. Timing would place the bulk of restrictions between 08-14z with lower MVFR/IFR cigs holding on above sites 16-18z while KOTM/KDSM should be back to VFR earlier. Will continue to monitor trends for 06z package./rev && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Small AVIATION...REV
Area Forecast Discussion
National Weather Service Pocatello ID
209 PM MST Mon Jan 17 2022 .SHORT TERM...Tonight through Wednesday night. Upper ridge stays in place through most of the short term. Weak shortwave passing through the panhandle and Montana Tuesday, flattening the ridge slightly and allowing some moisture to creep into the northeast corner Tuesday night into Wednesday. Moisture is limited and the system is weak, therefore accumulations are expected to remain light. Interestingly, there is some indication from the higher- percentile ranges of the NBM that some of that moisture could creep further south into the southern highlands as well. In the meantime, surface based inversions and fog appear to be the main threats. Have spread patchy fog across most lower elevation areas each night throughout the short term. DMH .LONG TERM...THURSDAY THROUGH NEXT MONDAY... A ridge of high pressure centered just off the Pacific coast will actually be building and increasing it`s influence across the west throughout the period, but it just won`t be quite strong enough to prevent an organized shortwave trough from cutting through it and crossing the forecast area in the Thu afternoon through Fri afternoon timeframe (splitting as it does so). The split itself should be of little consequence as it mostly occurs once the trough axis swings through...focus is more on how much moisture will we be able to wring out of this system? Deterministic models continue to advertise this as the best push of moisture we`ve seen in a couple weeks under our dry pattern of late, but still relatively modest as current storm total snow expectations are coming in at a dusting to 1 inch in the Snake Plain corridor and 1-4 inches across the srn/ern highlands, with the highest totals as you increase in elevation. One 500mb height ensemble cluster is actually dry (representing about 28% of the model space, ECMWF-heavy), and cluster analysis is quite weak overall with this feature as the ridge dominates the overall synoptic signal. The EC EFI (Extreme Forecast Index) does not advertise any unusual or high-impact snowfall compared to the model climatology. All pretty bland, right? That said, a handful of GFS/EC ensemble members do produce 2-4 inches of snow for places like Pocatello and Idaho Falls (which roughly matches the NBM 90th percentile) with wide spreads in box-and-whisker distributions, so there is a non-zero chance of the system either 1) overperforming in general or 2) perhaps resulting in some convergence-zone enhancement over the Snake Plain Thu night/Fri AM (based on the forecast sfc wind evolution with west winds coming in from the ern Magic Valley interfacing with sharp north winds coming down across the Snake). It`s difficult to diagnose this further just yet as we have no high- res guidance that goes out that far. Winds aren`t looking terribly impressive at all with this system. Largely ran with NBM guidance for the forecast for now. Dry wx is likely to ensue for the weekend as the ridge amplifies and drives the active storm track northward into Canada. - KSmith && .AVIATION... As has been the case for several days, fog and low stratus remain our forecast focus and greatest concern on the aviation front, otherwise coupled with continued very light winds and SCT to BKN high-level clouds streaming over the region. We`ve trended just slightly drier with slightly less fog/stratus coverage each of the last two nights, yet LIFR TEMPOs continued to verify Sun AM at KBYI/KPIH/KIDA, with briefer incursions still this AM at KBYI/KPIH. Overall we think tonight should mimic last night with a NE flow down the Snake Plain confining residual low stratus to srn reaches of the Magic Valley including near KTWF and KBYI...we`ll then have to watch for this activity to expand as the sfc cools/saturates, and for any new development elsewhere. NBM guidance (which is often too overdone with low cigs/vsbys) is actually running quite dry/optimistic tonight, but on the other hand, the HRRR (which has done fairly well over the last few nights) insists on greater coverage (fog in particular) tonight compared to last night. This may be overdone, but confidence in declaring that is low. Forecast temp/dew point depressions and very light winds should continue to support at least some potential...enough that we have again carried LIFR TEMPOs at KBYI (after 06z/11pm) and KPIH (after 09z/2am). We`ll hold at VFR for now at KIDA and KDIJ. KSUN will remain on it`s normal diurnal cycle...SE afternoon winds shouldn`t have enough fog/stratus to tap into to advect anything up the Wood River Valley, and NW overnight winds will maintain a hint of downslope drying, so only high-level clouds to deal with there. Precip impacts generally seem unlikely until Thu for all TAF terminals, and strong winds are not in the forecast. - KSmith && .AIR STAGNATION...Patchy fog remains a concern through midweek as weak upper ridging holds surface inversions in place. A weak feature will help to flatten the ridge slightly Tuesday into Wednesday, but impacts on the inversions will likely be limited. A stronger system is still forecast to arrive Thursday into Friday. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$