Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
371 FXUS65 KBYZ 121913 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 113 PM MDT Sun May 12 2024 .DISCUSSION... Through Monday Night... Midday satellite imagery shows a weak shortwave dropping thru far eastern MT, an upstream wave moving thru central AB, and stronger energy still off the BC coast (our main weather-maker for Monday). There are a few showers approaching Miles City and Baker, and over the Bighorns mainly south of Burgess Junction...otherwise it is currently dry as temps warm thru the 60s and into the lower 70s. The remainder of today will be dry for most places, but cannot rule out isolated showers & weak t-storms from mid afternoon thru sunset along an axis of low level baroclinicity and modest instability from Judith Gap and Roundup southeastward thru Billings, Sheridan and Broadus. Surface analysis shows backdooring NE-E winds as far west as Roundup and Busby, and hints of low level frontogenesis in this region. Will keep isold pops going thru 03z but this may be a bit ambitious. Late tonight into early Monday, per aforementioned energy in central AB, we could see a few light showers track across our north/northeast parts, but the better chances of precip will be to our north. By tomorrow afternoon our convective potential will begin to increase ahead of the stronger Pacific wave as it moves into the northern Rockies. Surface temps warming to the mid 70s to lower 80s on Monday will push surface-based capes to the 500-900 j/kg range, but a lack of greater low level moisture will keep the air mass from becoming more unstable, and bulk shear will remain relatively weak, so t-storms will remain non-severe (though could produce small hail). Greatest t-storm potential (20-30% chance) will be across our south and east where instability will be greatest. Synoptic forcing looks to lag the peak heating hours just slightly, arriving in our west by 00z. The cold front itself is also not well-defined. For these reasons we expect multiple rounds of showers and embedded weak t-storms from mid afternoon through Monday night. Best chance of precip over our far east will actually be late Monday night per timing of the shortwave itself. Also, by late Monday night, snow levels fall to near 9kft so the highest peaks of the Crazy and Beartooth-Absaroka Mountains will pick up some wet snowfall. One final note. To this point we have not seen any significant rises on stream levels along the foothills, courtesy of the current brief stretch of warm days. This will continue to be watched, but it appears we won`t see any water issues in the foreseeable future, especially considering the lower freezing levels arriving tomorrow night. Temperatures will remain above normal thru tomorrow before transitioning to a few cooler days. A few notable probabilities: 0.25" of rain Mon-Mon Nite: 60% mtns, 40% fthls, 10-20% elsewhere 0.50" of rain Mon-Mon Nite: 25% mtns, 15% fthls, 5-10% elsewhere 1" of snow above 10kft by Mon Nite: 20% JKL Tuesday through Sunday... Ensembles indicate additional energy following the front from Monday bringing increased chances for precipitation through Wednesday morning. For this time frame, the highest mountain peaks (generally above 9000 feet) could get around an inch of snow. Areas along the foothills have about a 40-50% chance of getting at least half an inch of rainfall with chances decreasing to 20% near the Dakotas border. Ensembles begin to differ Wednesday into Thursday on whether ridging will build in or unsettled weather will remain. With this uncertainty, the NBM keeps PoPs at 30-50% (mountains at the high end) for Thursday through Sunday. Overall, no major impacts are expected as rainfall amounts will be small with temperatures remaining seasonable through the period. High temperatures will be in the 60s and 70s. TS && .AVIATION... VFR will prevail over the next 24 hours. Isolated showers and t-storms are expected thru sunset. This activity will be weak but could produce erratic surface wind gusts to ~25kts. Confidence in a TS impacting a TAF site is low, and is greatest west of KMLS. There is greater potential for showers and t-storms across the region beginning Monday afternoon. Storms could produce moderate rainfall, small hail and brief MVFR conditions. JKL && .PRELIMINARY POINT TEMP/POPS... Mon Tue Wed Thu Fri Sat Sun ----------------------------------------------------------- BIL 050/079 052/066 048/065 048/075 052/070 043/064 043/064 23/T 79/T 55/T 22/T 33/W 34/W 34/W LVM 048/077 047/064 044/066 044/075 049/070 040/062 039/063 14/T 68/T 45/T 22/W 23/W 34/W 34/T HDN 046/080 050/067 046/068 044/076 049/070 043/066 042/066 23/T 78/T 55/T 22/T 43/W 33/W 33/W MLS 047/080 052/069 045/068 046/075 049/068 043/064 042/064 12/T 66/T 22/W 22/T 33/W 32/W 22/W 4BQ 046/080 051/067 046/065 044/073 050/070 043/066 042/064 22/T 76/T 33/W 12/T 22/W 32/W 22/W BHK 042/080 048/069 041/066 042/072 047/067 040/063 039/062 12/T 67/T 32/W 12/T 33/W 32/W 22/W SHR 044/079 047/064 044/063 040/074 047/072 040/067 039/063 25/T 78/T 66/T 22/T 33/W 33/W 33/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings