Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
970 FXUS65 KBYZ 270953 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 353 AM MDT Thu Jun 27 2024 .DISCUSSION... Through Friday night... A few weak showers and thunderstorms are moving along the western areas this morning. Aside from a few wind gusts in the 40s mph in the Livingston and Big Timber areas, little to no impacts have been observed with these storms. Sporadic chances for precipitation will continue this morning before increasing as storms move into the W/NW counties. This round of storms will be the first of the day, beginning between 12z-15z. There is potential for some of these storms to be strong, capable of producing heavy rain, gusty winds, and small hail. The next round of precipitation will be late morning/ early afternoon, beginning in the west once again. The latest SPC Severe Weather Outlook for today has most of the CWA in a Slight Risk (level 2 out of 5), and much of the eastern areas are in an Enhanced Risk (level 3 out of 5). The Enhanced Risk currently covers all of Fallon, Carter, and Custer Counties, as well as most of Power River, Rosebud, and Treasure Counties. A small part of eastern Musselshell County and extreme NE Yellowstone County (does NOT include Billings) are also included in the Enhanced Risk. The primary threats within the Slight and Enhanced Risk areas today will be large to very large hail, strong wind gusts, and a few tornadoes. Environmental parameters from the latest HiRes soundings show a murky picture. The latest HRRR is showing MUCAPE values rebounding to 1000-1500 J/kg in Wheatland, Golden Valley, Sweet Grass, and Musselshell Counties. PWATs are around or slightly above an inch, so moisture availability is not a huge concern, especially for the northern and eastern zones. There is a concern that the central and southern areas will struggle to develop and sustain strong to severe convection, due to S/SW flow at the surface feeding drier air into the environment. As for other parameters being sufficient, there is adequate deep layer shear, with values approaching 60 knots in HiRes soundings. Lapse rates are also fairly steep, in the 7-8 C/km range. In areas of sufficient moisture, strong deep layer shear, and strong low-level forcing/convergence, convection that develops and becomes sustained will be capable of severe to potentially significantly severe hail (up to 2.5" hail) and strong to potentially significant damaging wind gusts (up to 80 mph). Models show a messy environment across the CWA due to early morning convection and pockets of better moisture and forcing from local influences. Zooming out for a moment, the overall picture for today`s storm setup is a multimodal, multi-round event. A deep upper low and trof is setup over NE MT and Southern Canada, and a surface low moving across west-central Montana by early afternoon. A strong cold front associated with the surface low will produce a linear convective setup, with MCS/QLCS potential beginning in the western zones by late morning to mid afternoon (15-21z). The impacts associated with this potential MCS/QLCS will be strong winds and some hail. The SPC Outlook has tornadic potential highlighted, although based on current parameters and model soundings, the threat for QLCS type tornadoes seems quite low given that LCLs are very high and that line normal bulk shear vectors will be nearly parallel to storm and boundary motion. With this said, the concerns with the linear setup would be strong gusty winds, potentially severe hail, courtesy of steep low-level lapse rates, inverted-V sounding profiles, and very straight hodographs. The second mode of concern will be with discrete storms that are able to form in eastern Montana ahead of the approaching low and cold front. Models are struggling to show many storms forming and becoming strong to severe right now. There is a lot less certainty at this time with the potential for the discrete storms for this setup. The combination of notable cloud cover from morning convection along with the potential for dry air infiltrating low- mid levels is problematic. In the event that discrete storms are able to form in the east, there is a risk for a few tornadoes out east. Models are not indicating an environment that is favorable for tornadic development with very straight hodographs and little to no backing in vertical wind profiles. The lack of hodograph curvature, very high LCLs (>2000m, necessary is <2000m), questionable instability returns (maybe 1500-2000 J/kg of MUCAPE, highest in the far east), and weak surface shear gives us higher confidence that the risk for tornadoes is extremely LOW today. As for the timing of todays convection and precipitation potential, several rounds of precipitation are expected in the western zones with a 50-70% chance of showers and thunderstorms from 9am to 6pm MDT. As for the rest of the CWA, there is a 30-60% chance for showers and thunderstorms from Noon to Midnight. The large variation in timing is due to the multi-round nature of this event. High temperatures today will be in the 80s to mid 90s, warmest east of Billings. Friday will be cooler and breezier with highs in the upper 60s to mid 70s. Gusty winds will fill in behind the departing surface low, with gusts in the 25-40 mph for much fo the CWA. Higher winds are possible the western mountains and foothills, especially in Wheatland County where wind gusts in the 40s to 50 mph are possible. Matos Saturday through Wednesday... Ridging builds back over the region for the weekend bringing mainly dry conditions for Saturday and most of Sunday. Highs look to range from the 70s on Saturday to the 80s to 90s on Sunday, highest over southeastern areas. Ensembles remain in good agreement with another upper trough moving into the region by late in the day Sunday, bringing shower and thunderstorm chances through Monday (30-80% chance, highest over west and central areas). Modest CAPE and deep layer shear as well as a good moisture fetch over the area Sunday afternoon and evening could produce strong to severe thunderstorms. Cyclonic flow lingering over the area on Tuesday will bring a low chance (20%) for showers and thunderstorms across the north. Uncertainty remains in the upper level pattern as we head towards the middle of next week. Temperatures are forecast to range from the 70s to 80s for Monday through Wednesday. STP && .AVIATION... Isolated showers and thunderstorms were sliding east over the southwest mountains early this morning. Expect showers and stronger thunderstorms to develop in the west by 18Z today, moving east through the afternoon and early evening as a disturbance and associated cold front move through the region. The stronger storms could produce damaging winds and large hail, with the best chance to see this activity residing around and east of K3HT to KBIL. Northwest winds of 20-35 kts will accompany the front, gradually decreasing this morning. STP && .PRELIMINARY POINT TEMP/POPS... Tdy Fri Sat Sun Mon Tue Wed ------------------------------------------------------- BIL 090 052/074 047/077 053/087 060/080 055/080 054/082 5/T 31/N 00/U 01/B 56/T 22/T 11/U LVM 082 044/070 041/078 049/086 052/076 047/077 047/081 6/T 21/N 00/U 14/T 77/T 32/T 12/T HDN 093 052/076 045/078 052/092 058/081 053/081 051/084 4/T 31/N 10/U 01/U 56/T 32/T 11/U MLS 092 055/074 049/072 056/092 060/083 057/081 055/083 5/T 31/N 10/B 01/U 64/T 22/T 12/T 4BQ 095 056/078 049/075 055/096 060/082 057/082 054/085 4/T 30/U 00/U 01/U 34/T 31/U 11/U BHK 091 053/075 046/070 052/086 058/081 055/079 053/082 4/T 51/N 10/B 01/N 53/T 22/T 12/T SHR 092 051/076 043/079 053/094 056/080 050/080 049/083 3/T 31/N 00/U 01/U 36/T 31/U 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings