Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/27/22

Area Forecast Discussion
National Weather Service Denver/Boulder CO
830 PM MDT Tue Apr 26 2022 .UPDATE... Issued at 822 PM MDT Tue Apr 26 2022 Colorado is on the back side of the ridge. Skies are scattering out for the night but satellite water vapor imagery shows some moisture ahead of the incoming shortwave. It also shows trapped buoyancy waves all over eastern Colorado, which indicate stability especially over the mountains. There was a nice Denver Cyclone late this afternoon and early this evening which TDEN velocity captured really well. Winds are now turning to drainage. The forecast is on track with only minor updates this evening. && .SHORT TERM...(This evening through Wednesday) Issued at 231 PM MDT Tue Apr 26 2022 An upper level ridge is currently over the state with moisture lifting up and over bringing increasing cloud cover through the evening. With the cloud cover overnight lows will be more mild then the previous few day with temperatures in the mid to upper 40s on the plains. For Wednesday, cloud cover will persist through most of the day with weaker flow through 700mb. Lee cyclogenesis will bring a ENE push of winds at the surface during the morning and afternoon that could help to increase dewpoints over the northeastern counties and combat the warmer southwest flow over the southern foothills and Palmer divide area. The HRRR does tend to over mix in these types of marginal flow situations so don`t expect RH values to get into the single digits like it has represented, however, they could drop into the teens and even lower teens for the Palmer by the late afternoon. By Wednesday late afternoon and evening a shortwave will push through with minimal moisture but enough lift to bring a slight chance of showers to the higher terrain starting late Wednesday. With the warmer temperatures associated with this feature precipitation will mostly likely be rain with some snow mixed in possibly at higher elevations above 10,000ft. With some QG ascent and decent mid-level lapse rates some convective showers are possible. Highs will once again be on the warm side with temperatures reaching into the mid-70s and near 80 over the northeast with 40s and 50s in the high country. .LONG TERM...(Wednesday night through Tuesday) Issued at 231 PM MDT Tue Apr 26 2022 There will be a few ongoing showers and storms Wednesday evening that will dissipate pretty quickly after sunset. The rest of the night will be dry with slightly above normal temperatures. On Thursday, a ridge will be over Colorado in the morning with a trough advancing towards the state later in the day. Much of the day will be warm and dry across our CWA with highs in the mid to upper 70s across the plains. Lee cyclogenesis in advance of this trough will develop over southeast Colorado. This will keep winds easterly to southeasterly across the plains which will allow some moisture to remain in place. There are two affects from this. One is that it will most likely keep fire weather conditions below critical levels and, two, it may allow a dryline to form and create some showers and storms. If showers and storms were to form, it would be late in the day and overnight across the far northeast corner where the best moisture and forcing will be. The axis of the aforementioned trough will move over our forecast area Friday morning with the center of the trough over southeastern Wyoming. This will keep the best forcing to the north of our forecast area and subsidence will be overhead by late Friday into early Saturday. There will be some Pacific moisture that will combine with upslope flow to create snow showers in the mountains. Any accumulating snow should be light with minimal impacts. The primary concerns with this system will be winds and fire weather. The ECMWF EFI is beginning to show a signal for significant winds across the Colorado/Wyoming border as well as the far northeastern plains of Colorado. The GFS ensembles don`t show as high of a potential for strong wind gusts but the ECMWF ensembles have quite a few members that have over 50 mph gusts at Sterling. The ECMWF ensembles even have plenty of members that have DIA gusting to over 50 mph so that will need to be monitored. Sustained winds and wind gusts were increased in the forecast towards the NBM 90th percentile and ECMWF output. It`s possible that high wind highlights may be needed and blowing dust highlights could be needed, too. The fire weather issues are discussed in the fire section below. Ridging begins to build over Colorado late Saturday into early Sunday. Global models show a trough over the Intermountain West but don`t show much agreement in the exact positioning of this trough. Late Sunday into Monday will have the potential for a system to bring precipitation to the area but chances are low as of now. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 730 PM MDT Tue Apr 26 2022 Expect VFR conditions at all terminals through the TAF period. Skies are scattering out though there should be some mid to high level cloudiness overnight. A DCVZ is controlling winds this evening and currently seems to be drifting east of KDEN. It looks like winds at KDEN might come around northwesterly late this evening on their way to south-southwesterly drainage tonight. Brisk westerly to northwesterly winds may take over early tomorrow afternoon with gusts 20 to 25 knots, then winds come back around to drainage in the evening and overnight again. There may be some isolated, very light showers around tomorrow afternoon. No significant impacts are expected for the terminals. && .FIRE WEATHER... Issued at 231 PM MDT Tue Apr 26 2022 Elevated fire weather conditions will be possible Wednesday afternoon with low RH values in the teens, especially along the southern foothills and Palmer Divide. Winds speeds will increase by the afternoon with wind gusts staying under 25 mph. There will be elevated fire weather conditions across the Palmer Ridge on Thursday as relative humidity drops to the low teens. Wind gusts between 20-25 mph will be below Red Flag Warning thresholds so no highlights are expected at this time. There will be strong winds across much of our forecast area Friday and Saturday. The question with regards to fire danger will be whether the relative humidity will be low enough. For both days, areas north of I-70 look to have relative humidity above 15-20 percent so fire weather concerns will be a bit lower there. South of I-70 there is a much higher chance relative humidities drop into the teens. This will likely create critical fire weather conditions and fire weather highlights may be needed. In southern Lincoln County, extreme fire weather conditions could occur. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...EJD SHORT TERM...Bowen LONG TERM...Danielson AVIATION...EJD FIRE WEATHER...Bowen/Danielson
Area Forecast Discussion
National Weather Service Billings MT
211 PM MDT Tue Apr 26 2022 .DISCUSSION... Tonight through Wednesday night... Shortwave, seen on water vapor imagery, approaching from the Pacific NW was spreading mid and high clouds into the region per satellite and surface observations. Models rotate the wave NE through NW MT into Canada tonight. Some shortwave and jet energy will move across the forecast area, as well as a weak cold front. NBM and HRRR bring some QPF into the mountains this evening then lift it N of the area. Forecast reflects this idea with a chance of rain/snow over and near the mountains, then a slight chance of rain across portions of the northern tier of the area. There will be gusty SE winds over SE MT through the night and gusty SW winds over western areas this evening. Jet divergence and another shortwave will move into the area on Wednesday. These features will exit the area Wed. night. Another cold front will cross the area Wed. night. GFS soundings showed CAPE over the area Wed. afternoon and evening. The HREF brought convection through the area as well as weak updraft helicity tracks. A chance of showers and thunderstorms will overspread the area from the W in the afternoon, reaching KBIL after 21Z, and continuing to spread E during the evening. There will be a chance of rain E of KBIL after 06Z Thursday. Highs will be in the 50s and 60s on Wednesday. Arthur Thursday through Wednesday... Primary focus on storm system 1 which is expected to bring spreading scattered showers over the area on Thursday with a widespread area of rain Thursday night through Saturday with Friday night looking like the wettest period. This event will again favor southeast Montana with an inch of rain likely but winds do look to be weaker and temperatures will be a bit milder so snowfall will be limited to highest foothills and the mountains. There should be a break after this first system on Sunday with another system coming Sunday night or Monday with lower confidence on the track of the storm. Overall pattern will remain cool and unsettled as a result of a stream of energy flowing over Montana and Wyoming through the extended period. This will keep temperatures below normal with any moisture that is received will have a chance to soak into the landscape. borsum && .AVIATION... VFR will prevail tonight through Wednesday. However, isolated showers this evening will bring possible MVFR conditions, and showers and thunderstorms Wed. afternoon will be accompanied by MVFR/IFR conditions. Expect localized to areas of mountain obscuration this evening and Wed. afternoon. Southerly surface winds will be gusty W of KBIL through this evening, and winds will be gusty from the ESE from KMLS E tonight. Arthur && .PRELIMINARY POINT TEMP/POPS... Wed Thu Fri Sat Sun Mon Tue ----------------------------------------------------------- BIL 039/062 038/061 043/050 039/055 036/053 037/057 037/057 12/R 52/R 88/R 52/R 12/R 23/R 44/R LVM 033/058 035/058 037/047 034/054 035/052 034/055 034/054 35/T 43/R 99/O 31/B 23/R 24/O 54/O HDN 037/064 038/064 041/051 038/055 033/054 035/059 035/057 22/B 51/B 88/R 63/R 12/R 12/R 43/R MLS 035/061 039/061 044/049 037/049 034/048 034/053 036/053 20/B 50/B 88/T 74/R 21/E 11/E 33/R 4BQ 036/059 039/061 044/054 036/047 034/049 034/054 036/054 10/B 40/B 87/T 74/R 21/B 11/B 33/R BHK 029/053 034/056 039/047 033/041 031/044 031/049 034/051 20/B 40/B 88/T 85/O 21/E 11/E 33/R SHR 036/061 036/061 039/051 035/051 032/053 034/059 034/055 12/R 32/R 89/R 63/R 12/R 22/R 33/R && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$