Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
029 FXUS65 KBYZ 202130 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 330 PM MDT Mon May 20 2024 .DISCUSSION... Tonight through Tuesday night... Upper trough from W MT into ID was sending energy NE through the forecast area this afternoon. Jet energy was also moving through the trough, contributing to the lift. Best PWATs were in the SE at .5-.6 inches. Not much CAPE or shear is expected into the evening, but there were steep lapse rates especially in the W. There have been some isolated thunderstorms in the W, with scattered showers W and central moving E. The upper trough will swing through the area through Tuesday. PWATs will climb in the SE due to a Gulf fetch, reaching .5-.75 inches. Snow levels remain above 6000` through Tuesday evening. Mountains still look to receive heavy snowfall, especially the NE Bighorns where the EFI had .8-.9 in the southern portion of the NE Bighorns 00z Tue-00Z Wed, showing higher than the model climate for snowfall. Up to 16 inches are forecast, with highest amounts in the southern part of the mountains from 00Z tonight through 00Z Wednesday. Thus have upgraded the Advisory to a Winter Storm Warning. For the Beartooths/Absarokas, continued the Warning through 18Z Tuesday with highest amounts expected in the highest elevations where Beartooth Highway clearing operations were taking place. Thus this Warning was for impacts as well as snow amounts for up to 14 inches through Tuesday morning. Elsewhere, PoPs for showers and isolated evening thunderstorms will be from Rosebud County W this evening, then highest PoPs (70-90%) will be over S. Big Horn and Sheridan Counties for the rest of the night into early Tuesday. Lows will be in the low 30s to low 40s. Scattered showers and thunderstorms will be over areas from KBIL W Tue. afternoon, as well as over S and SE parts of the area. PoPs will be from 30% in KBIL to the 40s and 50s W of KBIL. Temps will be several degrees below normal. Zonal flow/weak ridging moves over the area Tue. night with quickly decreasing PoPs. Lows will be a little higher than they will be tonight. Arthur Wednesday through Monday... Ensembles and cluster analysis remain consistent in progging an upper low to lift into and cross the region Wednesday night into Thursday, exiting the east by early Friday. While confidence continues to increase in the overall pattern, uncertainty remains in the exact track of the low, as any shift north or south would affect precipitation amounts, along with temperatures. That would then affect snow levels and amounts as well. Currently the low is progged to slide across the MT/WY border and lift north and east into southeast MT on Thursday, moving into the Dakotas by early Friday. At this time, Thursday has the best precipitation potential, with precipitation chances ranging from 60-90%. Latest NBM probabilities show a 50-90% chance (highest over the west) of at least 0.25" through Friday and a 40-80% chance (highest over the Crazy Mountains into central zones) of at least 0.5". For the mountains, this translates to a 60% chance or greater of at least 6" of snow. Shortwave ridging builds in for the second half of Friday and Saturday, before another potential low pressure system is progged to move through the region on Sunday. High pressure then looks to build over the area starting Monday. Temperatures are currently forecast to range from the 50s to upper 60s on Wednesday, cooling into the 40s to 60s on Thursday. Highs in the 50s and 60s on Friday, warm into the 60s and 70s for Saturday through Monday. STP && .AVIATION... Scattered to numerous showers with isolated thunderstorms will affect the area this evening with MVFR/IFR conditions. Chances for showers will move S of KLVM to KBIL to KMLS overnight with MVFR/IFR conditions. Expect areas to widespread mountain obscurations. Scattered showers and afternoon showers and thunderstorms continue for Tuesday with MVFR/IFR conditions and areas to widespread mountain obscurations. Arthur && .PRELIMINARY POINT TEMP/POPS... Tue Wed Thu Fri Sat Sun Mon ----------------------------------------------------------- BIL 042/062 042/067 044/052 038/066 045/072 044/066 046/070 65/T 12/W 69/T 52/W 14/T 54/W 22/W LVM 034/061 038/061 039/050 035/063 041/063 038/062 040/068 55/T 16/T 99/T 42/T 16/T 54/W 22/W HDN 042/062 037/070 043/056 036/068 042/076 043/067 044/070 63/T 11/B 49/T 62/W 13/T 54/W 32/W MLS 042/063 040/070 045/060 037/063 043/074 045/066 045/070 11/B 11/B 27/T 62/W 11/B 43/W 22/W 4BQ 043/060 038/070 044/065 038/064 042/076 045/066 044/068 44/W 11/U 16/T 62/W 01/U 33/W 32/W BHK 040/063 037/070 042/062 035/061 039/073 043/064 042/067 12/W 01/U 17/T 63/W 11/U 33/W 22/W SHR 038/055 033/067 039/057 033/064 038/074 040/065 040/067 99/T 21/B 37/T 62/W 12/W 44/W 32/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Warning in effect until noon MDT Tuesday FOR ZONE 67. Winter Storm Warning in effect until 6 PM MDT Tuesday FOR ZONE 171. WY...Winter Storm Warning in effect until 6 PM MDT Tuesday FOR ZONE 198. && $$ weather.gov/billings