Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
928 FXUS65 KBYZ 252029 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 229 PM MDT Tue Jun 25 2024 .DISCUSSION... Through Wednesday night... Added low PoPs to the SW mountains after 21Z today, given webcams were showing growing cumulus there. There was also some cumulus over SE MT, but deeper clouds were moving SE out of the area. Upper ridge remains over the area tonight with some weak jet energy and shortwaves moving through the ridge. Model consensus just kept some low PoPs over the SW mountains through 03Z. Low- level flow will turn ESE overnight and bring Gulf of Mexico moisture into the area Wednesday into Wed. night. Shortwave energy will move E into the upper ridge Wed. afternoon and cross the area Wed. night, allowing SW flow aloft to move over the region. Weak cold front will move through the western part of the area Wed. night. PWAT`s will climb to 1-1.25 inches over the area during Wed. with highest values in the E. MLCAPE will be around 500 J/kg with higher values in the far SE. Bulk Effective Shear will range from 40 to 50 kt. Given the above, PoPs will increase over and near the western mountains to 20-40% Wed afternoon. Low PoPs will be over the NE Bighorns and far SE MT as well. 30-40% PoPs will overspread most of the forecast area Wed. evening, and will move E overnight, affecting KMLS, KBHK and Ekalaka late at night. CAPE`s were not that high, but shear will produce a few helicity tracks SW of KBIL per the HREF. Cannot rule out possible heavy rainfall with the storms due to high PWAT`s. High temps will be in the 80s to lower 90s on Wednesday. Arthur Thursday through Tuesday... There is good model agreement that a trough will make its way across the region Thursday. This will bring shower and thunderstorm chances (40-80%) to the region. An upper low to our north will bring southerly winds wrapping in moisture from the plains. Ensembles are currently showing PWAT values of over an inch for much of the region with some locations in the east seeing PWAT values over 1.25 inches. These values are around 150% of normal providing plenty of moisture for precipitation. The forcing mechanism for these storms will be a cold front associated with the low moving through Thursday afternoon. Looking at both ECMWF and GFS deterministic soundings, the ECMWF shows the more favorable solution at this time with steeper lapse rates through the lower half of the atmosphere. This equates to MUCAPE values approaching 2,000 J/kg with 0-6km shear values in the 40s kts creating a favorable environment for thunderstorms. Due to these factors the Storm Prediction Center has put our eastern CWA into a slight risk of severe weather with the main threats being strong wind gusts and large hail. NBM gives most of the area a 30-50% chance of seeing >0.25 inches of precipitation. Though high PWAT values and the scattered nature of thunderstorms will bring about the potential for localized heavy rainfall. Late Sunday into Monday there is good ensemble agreement in another Pacific trough entering the region bringing more precipitation chances. There is much more uncertainty with this system due to it being at the end of the forecast period. Thursday and Friday will be windy as lapse rates will be steep leading to mix down winds. Both days will see a >50% chance of getting a gust over 40mph across the region. Temperatures Thursday will be in the low 80s in the west with much warmer temperatures in the low to mid 90s in the east. Temperatures will drop Friday into the 70s for most due to the troughing and cold front. Temperatures will warm over the weekend with low to mid 90s returning in the east by Sunday. Another trough early next week drops temperatures back into the 70s for most Monday and Tuesday. Torgerson && .AVIATION... VFR will prevail over the next 24 hours. A few isolated showers or thunderstorms are possible over the southwest mountains late this afternoon and evening (after 21z). Tomorrow will see increasing cloud cover throughout the day across the region with showers and thunderstorms starting to make their way in from the west. STP/LT && .PRELIMINARY POINT TEMP/POPS... Wed Thu Fri Sat Sun Mon Tue ----------------------------------------------------------- BIL 056/087 062/088 054/073 047/079 054/087 058/078 054/079 01/U 26/T 41/B 10/B 13/T 65/T 31/U LVM 050/085 056/082 045/070 042/078 049/083 050/074 046/075 03/T 47/T 42/T 10/B 25/T 76/T 32/W HDN 054/089 059/091 052/074 045/081 053/091 056/079 051/080 00/B 36/T 51/B 10/U 12/W 66/W 32/W MLS 054/086 064/090 056/074 048/075 056/089 059/081 056/078 00/U 35/T 51/N 10/U 22/W 64/W 32/W 4BQ 056/089 064/095 056/076 049/078 055/095 059/081 055/078 01/U 34/T 41/U 10/U 21/U 44/W 31/U BHK 051/084 061/091 054/071 046/074 050/087 057/081 053/076 00/U 35/T 61/N 10/B 23/T 64/T 32/W SHR 052/089 059/091 050/073 044/081 052/092 055/079 049/079 00/B 24/T 31/N 10/U 11/U 34/T 21/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings