Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
266 FXUS65 KBYZ 151954 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 154 PM MDT Sun Sep 15 2024 .DISCUSSION... Through Monday night... Satellite imagery showed mid-level cumulus lifting in from the southwest this afternoon. As a weak wave of energy lifts north, isolated showers, and perhaps an isolated thunderstorm are possible over the southwest mountains and adjacent foothills late this afternoon into the evening. There are some hints that a few high-based showers could continue in the early morning hours across the west as well. Otherwise, a southeasterly low level jet will develop over southeast MT this evening (850mb winds of 30-40kts), bringing a mild night with poor to moderate at best RH recoveries over the eastern ridges, and keeping them relatively breezy (15-30 mph winds). Heading into Monday, an upper low pushing inland through California into Nevada will induce diffluent southerly flow over the region. This will allow for additional moisture and energy to advect north through the area bringing afternoon shower and thunderstorm chances, greatest over western areas (20-60%). Have introduced a slight chance (15%) of thunderstorms over southeast MT Monday afternoon and evening, with the hi-res models continuing to hint at instability and at least the possibility of a few storms. Another south to southeasterly low level jet looks to set up over southeast MT Monday night bringing warm conditions on the ridges, with poor to moderate RH recoveries. High temperatures on Monday will range from the upper 70s to lower 80s over the west, to the 80s to around 90 degrees over the east. Afternoon RH minimums will be higher than Sunday (20s and 30s), with winds a bit weaker. STP Tuesday through Sunday... Tuesday, an approaching upper low and trough will bring cooler and wetter conditions through the middle of the week. With this system, the chance for precipitation will be moderate to high across the forecast area. Deterministic models disagree on the extent and placement of precipitation on Tuesday, with some depicting a blanket of moisture across the region, while other models show a split in the moisture over SE MT. This discrepancy is likely due to models` depiction of a preceding cold front ahead of the upper low. The NBM probability for at least 0.5" of accumulated precip through Wednesday is 15-70%, with increasing chances from east to west. Breaking down this range for the following cities; Baker (20%), Sheridan (20%), Miles City (35%), Billings (50%), and Livingston (60%). High elevation snowfall will also accompany this system, with snow levels between 9,000-10,000ft Tuesday night. The probability of an inch of snowfall on the Beartooth Pass through Wednesday night is 25-50%. As for the highest peaks in the Absaroka/Beartooth mountains, the probability for 4 or more inches of snowfall, Tuesday to Thursday morning, is 50%. Those with recreation plans in the mountains should be prepared for wintry conditions. Wednesday, breezy conditions will impact much of the area, with gusts in the 20s-30s mph. The highest gusts are currently depicted north and west of Billings. The upper low will still be over MT, Wednesday, resulting in a 15-70% chance for precipitation (highest in west-central areas). The low will progress out of the region by Thursday, resulting in cooler temperatures and a modest chance for precipitation into the weekend. Ensemble members agree that another upper low or trough will dig into the Southwestern U.S., resulting in a weak troughing or zonal flow pattern over the Northern Rockies. Weak wave energy is depicted into next weekend, which could bring the chance for precipitation. High temperatures will be in the 70s west to around 90F in the east on Tuesday, 60s/low 70s Wednesday through Saturday and 60s next Sunday. Matos && .AVIATION... VFR will prevail over the next 24 hours, w/ periodic mid & high clouds. Isolated light showers and perhaps a thunderstorm are possible over the Beartooth-Absaroka Mountains and adjacent foothills in the late afternoon and evening hours. This evening, a southeasterly low level jet and resulting LLWS will impact locations east of KBIL (i.e. KMLS & KBHK). Additional shower/thunderstorm chances continue for Monday, mainly for areas west of KBIL. STP && .PRELIMINARY POINT TEMP/POPS... Mon Tue Wed Thu Fri Sat Sun ----------------------------------------------------------- BIL 053/082 055/080 053/067 052/069 048/072 049/070 048/064 01/B 26/T 65/W 32/W 12/W 23/W 44/W LVM 047/082 046/071 045/061 044/066 041/070 041/069 040/062 24/T 58/T 86/T 44/T 12/W 33/W 44/W HDN 051/084 052/083 051/069 049/070 046/074 047/071 046/067 00/B 14/W 64/W 32/W 12/W 32/W 33/W MLS 058/088 057/086 053/067 052/069 048/073 048/069 047/066 01/U 11/U 75/W 31/E 11/B 32/W 32/W 4BQ 057/090 057/089 052/071 051/070 048/073 049/069 047/067 02/T 21/B 62/W 11/B 12/W 32/W 22/W BHK 056/089 056/091 051/074 049/071 046/074 047/070 045/067 11/U 11/U 72/W 11/B 11/B 33/W 22/W SHR 050/088 050/084 046/073 044/071 042/074 043/071 041/068 00/U 13/W 42/W 12/W 23/W 33/W 33/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings