FXUS65 KBYZ 250311 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 911 PM MDT Wed Apr 24 2024 .UPDATE... Just enough moisture and upslope winds to generate very light shower activity over the western foothills. Added in slight chance (20%) chance for measurable precipitation for this area, including Livingston, through late tonight. Rest of the forecast on track. Chambers && .DISCUSSION... Through Thursday night... Temperatures have warmed into the 60s and 70s this afternoon as a ridge axis overhead was slowly shifting east. RH was down into the teens and 20s, although with generally light winds. Backing flow over the west will allow weak energy and moisture to begin advecting into the area this evening and overnight, bringing increasing cloud cover, along with small chances for showers (less than 25%). Lowering heights to the west and an upper low ejecting north and east from the SW US into the central Rockies and plains will allow for additional moisture and energy to advect into the region on Thursday. Precipitable water values will increase towards 0.80 inches, highest over the east. Periods of showers are expected to develop and move over the area Thursday into Thursday night. First western areas starting Thursday morning, and then eastern areas Thursday afternoon and evening as a surface trough develops. Precipitation chances look to range from 40-90% over the west, to 15-30% over central areas, and 40-70% over the east. With modest instability of up to 1000 J/kg of MUCAPE over the east, but weak deep shear (25 kts or less), storms could be strong briefly, but tend to pulse up and down. A few thunderstorms are also possible over western areas during the afternoon and evening, but are expected to be weaker. Precipitation totals Thursday into Thursday night look to range from 0.10 to 0.25 inches over eastern areas, to 0.25 to 0.60 inches over western areas, and totals of 0.10 inch or less over central areas. Snow levels will be around 8500 feet to start Thursday, falling to as low as 7000 feet Thursday night. Western mountains above 7000 feet could see a quick few inches of snow. STP Friday through Wednesday... For Friday, a closed low just to the SE of MT will bring precip to SE MT. Meanwhile, as a Pacific shortwave trends southeast off the coast of WA, our western mtns will see an increased chance for precip. Best chances for precipitation will be Friday morning through Sunday morning. With the current setup for the best forcing, the west and far east have the higher QPF forecast. For this same time period, west of Billings, as well as Carter Co., have at least a 25% chance of getting a half and inch of water (higher chances in higher elevations). The Crazy Mountains as well as the Beartooth/Absarokas have about a 30-50% chance of at least a foot of snow above ~7000-8000 ft. There is some uncertainty in the ensembles regarding snow amounts in the Crazy Mtns, so this will need to be monitored. With this, a Winter Storm Watch has been issued for these aforementioned mountains with 12-20 inches of snow possible. Take the necessary precautions if recreating in the mountains during this time period. Into Monday evening, a shortwave to our north will drop a front through bringing some light precip with it. For the remainder of the period, slight ridging will build in to provide drier conditions. High temperatures will be in the 50s/60s Friday through Tuesday, warming into the 60s/70s by Wednesday. TS && .AVIATION... In general, VFR will prevail through the period. Mid and high clouds will increase from the southwest this evening, with isolated to scattered showers spreading into the southwest mountains later this evening and overnight, VC KLVM. Expect chances of precipitation, and weak thunderstorms to increase on Thursday, with local MVFR reductions possible. STP && .PRELIMINARY POINT TEMP/POPS... Thu Fri Sat Sun Mon Tue Wed ----------------------------------------------------------- BIL 046/069 048/061 045/057 041/063 042/068 043/067 041/072 12/W 46/W 67/W 23/W 13/W 42/W 22/W LVM 042/065 042/052 040/051 038/059 038/062 038/063 038/067 26/T 89/W 88/W 45/W 25/T 43/W 23/W HDN 041/071 046/065 045/059 041/064 039/071 042/070 040/075 02/W 34/W 56/W 33/W 13/W 42/W 22/W MLS 044/073 046/070 045/058 039/058 037/069 044/068 043/072 02/W 23/T 43/W 21/E 01/B 31/B 11/B 4BQ 041/074 046/065 045/054 039/055 037/067 043/069 042/073 03/T 35/T 55/W 32/W 01/B 21/U 11/U BHK 039/075 044/064 041/054 034/054 034/065 040/066 040/069 05/T 56/T 53/W 22/W 11/U 21/U 11/U SHR 042/068 044/060 042/052 036/058 036/066 038/069 039/072 03/T 46/W 78/T 44/W 12/W 32/W 12/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Watch in effect from late Thursday night through late Saturday night FOR ZONES 67-68. WY...None. && $$ weather.gov/billings