Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
176 FXUS65 KBYZ 300930 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 330 AM MDT Sun Jun 30 2024 .DISCUSSION... Today through Monday Night... A hot Sunday is in store as ridging continues to build over the Northern Rockies. Temperatures will climb into the mid 80s to 90s. Some locations in the south and east could approach 100F. The record high temperature for today in Sheridan, WY, is 98F. the current forecast has them reaching 97F so tying and even breaking the record is certainly possible. The main story today will be the severe weather risk. A Marginal Risk (level 1 out of 5) covers the entire forecast area, while a Slight Risk (level 2 out of 5) covers a sizable portion of east- central Montana. The primary risks associated within the outlooks will be wind and hail. Heavy rainfall is a secondary risk. The wind threat is currently a greater concern within our forecast area with environmental parameters favoring severe to potentially significantly severe wind gusts. The main round of severe weather will come with an approaching upper trough and an associated cold front. At the surface, an area of low pressure will move into southeastern MT/ northeastern WY. The presence of this surface low may allow for isolated convection to develop in eastern Montana ahead of the cold front. With cold frontal passage not expected until the late afternoon hours beginning out west, the potential for discrete thunderstorm development cannot be entirely ruled out as strong diurnal heating will result in higher instability. The problem with pre-frontal convection developing and sustaining itself is a strong cap in place. With soundings depicting warm profiles, it will be difficult for parcels to break through strong capping, especially when dew point depressions are 30-50F. As for the convection expected to form with the passing cold front, models continue to show storms firing in lee of the Absaroka/Beartooths, Belts, Crazies, and Gallatin mountains by mid- afternoon. HiRes soundings show MUCAPE values between 500-1000 J/kg, along with deep layer shear will be around an inch east of Billings along with steep lapse rates in the 8-9 C/km range, values between 40-60 knots, in the western areas. As convection progresses east- northeast, a better environment will allow for storms to strengthen. MUCAPE values around 2000 J/kg in eastern MT and DCAPE values in excess of 1500 J/kg will be more than sufficient for storms to produce wind gusts of 60-75 mph. As for the hail potential, PWATs values around 1-1.2" will be present east of Billings along with 8-9 C/km lapse rates. Significant hail parameter values up to 1-1.5 indicate the potential for severe hail, however, models are generally bullish on storms becoming strong enough to tap into hail potential. Despite potential limitations, large hail of 1-1.75" (quarter to golf ball sized) is possible with the strongest storms. Timing for convection today will be from 3pm to Midnight, with the cold front departing the far east by the latter. The chance for showers and thunderstorms is 60-80% west of Billings in the afternoon. As storms move east, the highest chances will remain just north of Billings, at 30-60%. As for Billings and locations south-east, there is a 15-30% chance for showers and thunderstorms. Lingering moisture behind the cold front will bring the chance for more showers and sub-severe thunderstorms to much of the west- central areas Monday morning. Precipitation probabilities are 25-60%, higher in the western mountains. High temperatures on Monday will be in the 70s to low 80s. Another round of strong to severe storms is possible Monday afternoon, with a Marginal Risk (level 1 out of 5) covering southeast MT and northeast WY. The forcing mechanism for this round of storms looks to be a weak cold front. The primary risks will be wind and hail. Matos Tuesday through Sunday... Although this period begins at the tail end of storms and a strong surge of moisture producing precip for the start of the week, that doesn`t mean we`re out of unsettled weather just yet. Broad cyclonic flow will persist over Montana and embedded, weak shortwaves will continue to bring off and on periods of showers and storms to southern MT and northern WY. Tuesday will see the weaker side of things, so while containing small chances for showers and storms, any that form will be relatively light, producing minor rain amounts and small hail. The `best` shot for a stronger system still looks to be Wednesday as a more dynamic shortwave crosses the area and brings a cold front with it. While some moisture is brought it, it will be limited due due not getting a good shot of moisture from the Gulf, as west to northwest winds persist through the day, and on top of that, shear is a bit on the low side at only 30-35 kts. Still a day to keep an eye on, especially with it being the night before the 4th of July. Speaking of, the aforementioned shortwave persists into Thursday and drags it`s storm potential with it, albeit with weaker forcing than before. Coverage is still moderate, with the chance for rain/storms 40-60% across southeast Montana. Current ensemble consensus does have storms moving out of the area in the evening, but that could easily change over the coming days. Be prepared for rain and storm potential if you have 4th of July plans. While ensembles are still in agreement for having a prominent upper ridge come across the western United States for Friday and into the weekend, there are hints within some of its members and from deterministic models of a wave pushing down through Montana and continuing to bring moisture and storm potential tot he area going into the weekend (vs being hot and dry if the ridging prevails). Something to keep an eye on over the next few days. Vertz && .AVIATION... Building high pressure aloft will bring widespread VFR today. By mid-late afternoon, expect scattered strong to severe thunderstorms to develop west of KBIL, possibly affecting KLVM-K6S0-K3HT with brief MVFR and strong wind gusts before 00z. Thunderstorms associated with a cold front will arrive around 00z for KBIL and progress east to KMLS between 00z and 03z. Primary hazards with these storms will be strong winds and hail, potentially impacting K3HT-K6S0-KBIL-KMLS. Wind gusts of 50-65 knots will be possible with strong tstorm outflow. Hail of 1-1.75" (quarters to golf balls) will also be possible with the strongest storms. TS POTENTIAL TIMES: KBIL: 21z-03z KLVM: 21z-03z KMLS: 00z-06z KSHR: 21z-03z Matos && .PRELIMINARY POINT TEMP/POPS... Tdy Mon Tue Wed Thu Fri Sat ------------------------------------------------------- BIL 089 060/080 058/079 055/082 054/075 052/082 055/087 2/T 23/T 43/T 13/T 45/T 21/U 11/U LVM 085 053/077 048/075 047/078 046/074 046/080 050/084 4/T 45/T 63/T 13/T 34/T 11/U 11/U HDN 095 058/080 055/079 051/083 051/076 050/082 051/088 2/T 23/T 54/T 13/T 55/T 21/U 11/U MLS 092 061/079 058/078 054/083 055/074 052/081 056/086 1/U 53/T 24/T 13/T 45/T 21/U 11/U 4BQ 096 061/080 057/077 053/086 054/075 052/079 054/084 1/U 25/T 44/T 03/T 55/T 21/U 11/U BHK 084 059/080 054/076 052/080 052/072 050/078 052/082 0/N 44/T 13/T 13/T 46/T 22/W 11/U SHR 097 055/076 050/076 048/083 048/074 046/078 048/085 2/T 26/T 74/T 12/T 44/T 21/U 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings