Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
153 FXUS65 KBYZ 020326 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 926 PM MDT Sat Jun 1 2024 .UPDATE... Updated forecast for latest precipitation and thunderstorm trends for tonight into tomorrow morning. Latest models pushing a bit more activity through the area as a weak Pacific disturbance crosses the area. Overall this activity should be fairly weak with precipitation amounts under a tenth of an inch at most. However the latest HRRR runs have steadily increased wind gusts associated with the strongest showers/thunderstorm, with the 01/02z run advertising near 60mph gusts into the Billings area around midnight tonight, pushing into the Miles city area by 3 am. Timing of winds this strong is not optimal happening after surface inversion has taken hold, particularly given the lack of strong convection to push the strong winds through the inversion to the surface. While not completely discounting the isolated strong wind gust potential, did add HRRR wind gusts into the forecast over the top of the NBM winds. However, knocked wind gusts down to around 35 mph at most. Observations have been showing gusts in the mid 40 mph range over western valleys (Helena/Butte) with convection over the past hour, so will continue to monitor this isolated wind threat through the night tonight. Rest of the forecast in pretty good shape. We will just have to monitor how the shower/isolated thunderstorm activity continues to evolve tonight. Chambers && .DISCUSSION... Rest of Today through Sunday Night... Satellite imagery show a low amplitude ridge shifting across our region with short wave energy upstream tracking through the Pacific NW into Idaho. These upstream waves along with a gradual increase in PWATs (to near 0.75") will bring us a chance of showers and weak thunderstorms tonight into Sunday (20-40%). Mesoanalysis indicated increasing shear and CAPE (250-500 J/Kg) at mid afternoon...especially over the southern portions of our CWA near the foothills. By late afternoon we still expect to see weak convection develop in our far west as short wave energy moves into the area. Any storms will remain weak this evening, but could produce some erratic wind gusts (maybe up to 35 mph), mainly W-NW of Billings where CAM`s paint the best probabilities, while a stronger cell near the foothills could also produce some small hail due to better shear. Models suggest isold/sct convection will hold together and continue east overnight with an associated Pacific front. Models target areas along and north of I-94 activity with the best chance of measurable precipitation in the overnight hours to early Sunday morning. Some showers may linger here and there over the eastern border counties and also the mountains early...but by Sunday afternoon most of the forcing has moved east and subsidence takes over for dry conditions. It looks to be a bit cooler (highs low- mid 70s) w/ mixed west winds gusting perhaps into the 20s. One other item to note is the southeasterly low level jet expected to develop this evening in southeast MT. HREF shows dewpts rising to near 50F with increasing elevated instability. However, forecast soundings suggest a decent cap in this region, and thus models do not initiate any convection. This is nonetheless something to be aware of in case short wave influences manage to erode that cap. BT Monday through Saturday... Monday will see a cold front move through the region bringing precipitation chances back to the region Monday afternoon into evening. Looking at convective potential, the ECMWF ensemble gives the region a near 0% chance for >500J/kg of CAPE. Looking at GFS soundings, this in mainly due to mid level lapse rates during the day and low level lapse rates during the evening not being steep enough. PWAT values will get over 1 in indicating a moist environment. Models are not showing a low level jet setting up near the Dakotas. Jet forcing also does not appear to be very strong. Given these factors, precipitation will likely be dependent on forcing from the cold front leading to scattered showers and general thunderstorms. WPC clusters show disagreement in precipitation amounts but even the highest cluster only showed about 0.2 inches of precipitation or less. NBM is giving most of the region a 30-60% chance of getting >0.1 inches of precipitation. Locations that get under thunderstorms may get more rain with local 0.25 inch readings possible. Behind the front, 700mb winds will be strong out of the west in the 30-40kt range over the plains and near 50kts over the western mountains. Low level lapse rates will be in the 8-9C/km range leading to efficient mix down for Tuesday and Wednesday afternoon. Tuesday, most of the region has a >50% chance of getting a wind gust over 40mph with locations in Wheatland County having a >90% chance for getting a gust over 50mph. Winds Wednesday will be similar to Tuesday with probabilities slightly lower. After the system moves through Monday into Tuesday, ensembles are in good agreement that some sort of ridging will return to the region increasing temperatures and bringing dry conditions. There is disagreement in exactly how the ridging will look which will determine how high our temperatures get. Max temperatures Monday will be in the low 70s in the foothills to low 80s east of Billings. The cold front will bump down temperatures into the low to mid 70s for Tuesday. Once the ridging takes over, Wednesday through Saturday will see above normal temperatures in the mid 70s to mid 80s across the region. Torgerson && .AVIATION... Scattered showers and isolated thunderstorms will move E through the area tonight. The best chances for thunderstorms will be near KMLS between 06Z and 12Z Sunday. MVFR is possible in thunderstorms. There will be isolated to scattered showers and a few thunderstorms from KBIL W Sunday morning. Scattered showers and isolated thunderstorms will affect areas W and S of KBIL, including KSHR, Sunday afternoon. Gusty NW surface winds are expected at KMLS between 06Z and 13Z Sunday. A wind gust of 30-40 kt is possible at KBIL between 06Z and 08Z, but confidence was not high enough to include it in the TAF at this time. Localized to areas of mountain obscuration will occur through Sunday. Arthur && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 052/075 055/078 050/074 054/079 050/081 055/082 058/083 32/T 12/T 71/N 00/U 00/U 11/U 11/U LVM 046/074 053/071 044/071 053/079 048/083 053/082 053/081 45/T 18/T 70/N 00/N 01/U 11/U 22/T HDN 050/077 053/081 049/076 053/080 048/082 052/084 056/085 31/U 12/W 81/B 00/U 00/U 10/U 21/U MLS 053/077 053/081 051/074 054/075 048/080 052/083 054/081 41/B 11/B 81/N 00/N 00/U 00/U 11/U 4BQ 053/076 053/084 052/072 053/076 048/079 053/083 054/081 10/B 10/B 71/B 00/U 00/U 00/U 11/U BHK 052/076 051/082 049/072 050/074 045/077 048/080 049/076 33/T 12/T 71/N 00/N 00/U 00/U 11/U SHR 048/074 050/081 047/073 050/079 048/081 051/084 053/082 03/T 11/B 61/B 00/U 00/U 11/U 21/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings