Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
625 FXUS65 KBYZ 111431 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 831 AM MDT Sat May 11 2024 .UPDATE... Satellite imagery shows a dry NW flow with an upstream shortwave passing thru southern SK...and only a few high clouds in our region. Temps today will jump into the 70s and a few spots may touch 80F, with emerging mixed W-NW winds. High res models continue to suggest very weak convection this afternoon and evening, with development along an area of low level convergence (as winds shift to the NW-N late today). We should reach convective temps and thus achieve a little skinny sbcape...so diurnal light showers, sprinkles and virga seem like a good bet. Have expanded coverage of low pops just a bit, otherwise forecast is in good shape. JKL && .DISCUSSION... Today through Sunday Night... Warmer and mainly dry conditions can be expected across the area today with downslope flow in place. A weak shortwave crossing the region may generate a few light showers or sprinkles (less than 20% chance) during the afternoon and evening over portions of the area, but for most it should be a dry Saturday. A rumble of thunder isn`t out of the question over the Bighorns. With downslope flow in place, temperatures will warm into the 70s and approach the lower 80s for a few locations today. Another shortwave dropping into the region from the northwest will bring isolated to scattered showers and thunderstorms to the area Sunday afternoon and evening. The wave will also knock temperatures down a few degrees from Saturday, and allow winds to shift around out of the east by Sunday night. Highs in the lower to middle 70s can be expected. STP Monday through Saturday... Monday will start out similar to Sunday with shortwave ridging bringing temperatures 10-25 degrees above average in the mid to high 70s. Throughout the day Monday however, a shortwave trough will begin to make its way into our area flattening the ridge. This will spin up a low pressure system that will track along the international border. This low pressure system will drag a cold front across the region bringing precipitation chances. Currently, the GFS is showing CAPE values of near 1,000 J/kg for some locations. However, none of the ensembles are showing values this high, generally keeping them below 500 J/kg. Dew point depressions will be high with temperatures in the 70s and dewpoints in the 40s, this is leading to GFS soundings having ML CAPE roughly half of surface CAPE. This could limit convective activity if there is good mixing which lapse rates suggest there will be. Ensembles show PWAT values being near 0.7 and GFS soundings show 0-6KM shear over 30kts for Billings. Taking into account the shortwave trough and cold frontal forcing lead to the conclusion that there will be general thunderstorm activity Monday evening into Monday night. The cold front will bring in stronger winds for Tuesday with most of the region having a 40-60% chance of getting a wind gust over 30mph. Tuesday will see the return of 50-70% Pops as we get wrap around from the low. With winds out of the north/northwest, the best chances for precipitation will be locations in the higher terrain that get upslope with northerly winds. The combined rounds of precipitation will bring a 40-70% chance for 0.25 inches of rain for most. The cold front will bring temperatures down into the 60s for Tuesday. Wednesday through the rest of the long term bring significant uncertainty as ensembles have still have not come into agreement on the pattern. Some models show the return of troughing and therefore cooler temperatures and precipitation chances, while others want to show a ridging pattern returning leading to warmer temperatures and drier conditions. This uncertainty leads to 20-40% Pops everyday and temperatures in the mid 60s to low 70s. This is subject to change over the coming days as models hopefully come into better agreement and details become more clear. Torgerson && .AVIATION... VFR will prevail over the next 24 hours with mostly light winds (morning gusts to 25kts are occurring along the western foothills). Expect scattered cumulus clouds this afternoon and evening, some of which could produce isolated light showers, sprinkles or virga. Any light showers could produce erratic surface wind gusts to 20kts. JKL && .PRELIMINARY POINT TEMP/POPS... Tdy Sun Mon Tue Wed Thu Fri ------------------------------------------------------- BIL 078 048/075 048/077 050/066 045/067 046/073 050/072 1/B 12/T 16/T 58/T 33/R 24/T 33/T LVM 077 046/078 047/074 045/063 041/066 044/071 045/072 1/B 12/T 16/T 48/T 33/R 24/T 23/T HDN 079 046/076 045/078 048/068 044/067 043/074 047/073 1/U 12/T 15/T 67/T 33/R 33/T 32/T MLS 079 048/076 047/079 051/066 044/065 044/072 047/071 0/B 12/T 13/R 55/T 23/R 23/R 32/R 4BQ 076 048/076 044/080 049/068 044/064 044/071 045/070 0/U 12/T 12/R 65/T 33/R 22/R 32/T BHK 078 045/074 043/076 048/067 041/063 042/069 042/068 0/B 12/T 22/R 65/T 22/R 22/R 32/R SHR 077 044/075 044/077 045/065 041/063 040/071 044/071 0/U 13/T 15/T 68/T 44/T 23/T 32/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings