textproduct: Billings

KEY MESSAGES

- Transition to cooler widespread rain tonight through Thursday.

- Moderate to heavy snowfall on north facing slopes of high country (mainly above 7000 ft) tonight through Thursday. The opening of the Beartooth Highway on Friday may be impacted. - Over a half inch of precip is expected along southern mountains and foothills (>75% chance).

- Warming trend Friday through early next week.

UPDATE

Satellite imagery shows an upper low over southern AB while mesoanalysis has a 110kt H3 jet diving into northern ID. Over the last several hours we have seen shower activity increase as the large scale ascent increases behind a late afternoon frontal passage that has shifted winds to northerly. KBLX VAD winds show NNE winds to near 11kft MSL, and appropriately we are seeing areas of showers (w/ very little lightning) intensify near and west of Billings. Energy dropping out of Canada will push thru western MT into WY over the next 24hrs, a favorable track for upslope precip initially over our west then spreading eastward, with heaviest amounts in southern upslope areas (i.e. north aspects). Still looking for an eastward propagating axis of mid level frontogenesis that should be a focus for heaviest precip as it passes.

Forecast is on track for a period of rain over much of the region tonight and Thursday. Have adjusted pops/wx per current conditions and higher confidence. Couple items to watch. First is how low snow levels will fall. All indications are for snow down to ~6kft MSL by early tomorrow, and this is consistent with what mesoanalysis is showing upstream, but perhaps dynamic cooling can allow a brief change over to wet snow a bit lower than that. The higher elevations just south of Red Lodge and near Story may see wet snow w/o accumulation. Second is t-storm potential in the east as surface trof will still be near the MT/Dakotas border at midday Thursday. There is ample spread here, but some high res models show healthy convection developing and lifting thru our far east in the afternoon...though greater instability overall is expected to remain in the western Dakotas. Nonetheless this is something to monitor and have raised pops/QPF a bit in our far east tomorrow. Ingredients shouldn't support severe storms, but small hail and local downpours are possible (pwats up to 0.75").

JKL

AVIATION

Scattered showers with isolated thunderstorms will move through the region this afternoon. Behind a cold front this afternoon and evening, winds will become northwesterly with gusts 25-35 kts possible. Additionally, MVFR/IFR conditions will become more likely as lower ceilings prevail this evening. Mountain obscurations are expected this evening through the period. TS

PRELIMINARY POINT TEMP/POPS

Thu Fri Sat Sun Mon Tue Wed ----------------------------------------------------------- BIL 043/056 039/068 044/079 051/086 053/089 054/085 053/079 +9/T 10/U 00/U 01/U 01/U 12/T 33/T LVM 035/053 031/066 039/076 045/081 048/083 048/077 045/071 +9/T 20/B 00/U 01/B 01/U 14/T 45/T HDN 041/056 036/069 039/079 046/086 049/089 051/085 051/079 +9/R 20/U 00/U 00/U 00/U 11/B 32/T MLS 043/058 039/069 041/078 048/086 051/089 056/088 055/082 67/R 30/B 00/U 00/U 00/U 11/N 23/T 4BQ 042/055 040/066 040/076 047/084 051/089 057/086 055/079 28/T 71/B 00/U 00/U 00/U 01/N 23/T BHK 038/061 038/064 037/075 046/084 050/088 056/087 054/082 26/T 74/W 10/U 00/U 00/U 11/N 23/T SHR 039/046 032/063 034/073 040/081 043/086 045/082 044/076 3+/R 50/B 01/U 00/U 00/U 12/T 34/T

BYZ WATCHES/WARNINGS/ADVISORIES

MT...Winter Storm Warning in effect until 6 PM MDT Thursday FOR ZONE 67. Winter Weather Advisory in effect from 3 AM to 9 PM MDT Thursday FOR ZONE 171. WY...Winter Weather Advisory in effect from 3 AM to 9 PM MDT Thursday FOR ZONE 198.