Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
836 FXUS65 KBYZ 181617 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 1017 AM MDT Thu Jul 18 2024 .UPDATE... Satellite imagery shows a weak low along the NW MT/Canada border, riding the crest of a strong 590dam ridge. Weather is quiet this morning but we will see convection develop early this afternoon, 19-20z per latest high res models. Pwats increase to 0.90-1.00" today, with moisture at mid-upper levels, and forecast soundings are suggestive of wet microbursts (steep low level lapse rates and surface temps in the mid-upper 90s). Confidence in a few severe wind gusts has increased such that the latest day1 outlook from SPC has highlighted the NW quadrant of our forecast area in a marginal risk of severe wx today. This includes an area from Livingston to Hardin northward to Harlowton and Ingomar. Locally heavy rain is also a good bet w/ storms today, along with small hail. Heads up if you have outdoor plans today. As the PV max moves thru north central then southeast MT, the chance of showers and embedded t-storms continues thru the night over our eastern zones. Forecast has this covered well. JKL && .DISCUSSION... Through Thursday Night... A shortwave will track along the top of the ridge today flattening it out. This will bring a 30-60% chance for precipitation across the area starting in the afternoon. Shear and instability will be limited with 20-30kts of shear and <1,000J/kg of CAPE. This will act to limit severe potential but inverted V soundings with moist upper levels indicate the potential for effective evaporational cooling leading to strong wind gust potential in excess of 50mph in thunderstorms. Our warm temperatures will act to limit large hail potential which is reflected in the HRRR Neural Network showing wind as the main threat today. Storms will initially develope over the high terrain in the west before moving across the region. Tomorrow morning, HREF is showing favorable convective conditions reemerge near the Dakotas border and lasting through the afternoon. Downsloped 500mb flow will overcome falling heights from the trough to bring hot temperatures in the mid to high 90s, with some locations along the Yellowstone east of Billings having a 30-50% chance of reaching 100. Friday will see heights continue to rise bringing temperatures in the high 80s to mid 90s. Persistent easterly winds will keep good moisture in the region keeping RH values in the high teens and 20s today and 20 to mid 30s tomorrow. Torgerson Saturday through Wednesday... Model ensembles continue to indicate high confidence in an upper level ridge dominating the weather pattern through the extended forecast period. So no significant changes to previous forecasts. Expect above normal temperatures with highs in the 90s to near 100 degrees. Lows will be in the 60s across the plains. The hottest day may be next Wednesday when models show a 30-50% chance of reaching 100 degrees in the river valleys including Billings and Miles City. As for precipitation...Deterministic Models are now showing a weak back door front slipping into the eastern plains late Saturday. There is enough related forcing to produce isolated to scattered convection through Saturday evening in our central to eastern zones so we added some isolated POPs. PWAT values will often be as much as 120-125% of normal over the weekend. So a few storms could produce locally heavy rainfall. Otherwise...we may only see a slight chance of late day convection over the mountains to the west each day...with a strong mid level cap possibly in place over much of the area toward Tue/Wed next week limiting any notable convective activity. BT && .AVIATION... Expect scattered thunderstorms with movement from west to east this afternoon and evening. Today`s storms will have the potential to produce strong surface wind gusts (to 50+ knots) as well as local MVFR-IFR in heavy rain, and small hail. All TAF sites are at risk of seeing a TS today. A weak disturbance passing thru eastern MT will keep the risk of showers and weak t-storms going thru the night in southeast MT (east of KBIL). Otherwise, VFR conditions will prevail over the next 24 hours, while slant range visibility is reduced at times due to wildfire smoke. TS POTENTIAL TIMING TODAY: KBIL 22-06Z KLVM 19-04Z KMLS 02-10Z KSHR 21-06Z JKL && .PRELIMINARY POINT TEMP/POPS... Tdy Fri Sat Sun Mon Tue Wed ------------------------------------------------------- BIL 097 063/093 065/093 063/092 062/092 062/097 065/099 2/T 40/U 02/T 11/U 00/U 00/U 01/U LVM 094 056/093 056/092 055/090 053/091 054/096 058/097 4/T 41/U 11/U 11/U 00/U 01/U 12/T HDN 099 061/093 060/093 061/092 059/093 059/097 061/099 1/U 51/U 02/T 21/U 00/U 00/U 00/B MLS 096 067/089 064/090 063/089 063/090 064/094 065/096 0/U 52/T 12/T 10/U 00/U 00/U 00/U 4BQ 096 066/089 063/090 061/088 061/090 062/093 064/097 0/U 43/T 12/T 11/U 00/U 00/U 00/U BHK 093 063/088 060/088 058/087 059/087 059/091 060/093 0/U 54/T 12/T 11/U 00/U 00/U 00/U SHR 097 060/090 057/089 056/088 054/089 055/093 058/096 2/T 42/T 02/T 12/T 01/U 00/U 01/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings