Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
858 FXUS65 KBYZ 200127 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 727 PM MDT Fri Jul 19 2024 .UPDATE... Isolated thunderstorms that developed east of Billings in the afternoon are diminishing, and should taper off completely by sunset. The remainder of the night will be dry under mostly clear skies, w/ light winds. Satellite imagery shows the next upstream wave moving from BC to AB. As it drops southward in the northerly flow, we will see a greater chance of convection across the area beginning somewhat early tomorrow, around noon. Forecast has this covered well. Made some evening pop/wx adjustments and cooled some of the notoriously cooler valleys tonight. JKL && .DISCUSSION... Through Saturday Night... Isolated showers and thunderstorms were found over the southern mountains this afternoon with winds gradually shifting around to the northeast over the area as a weak shortwave dropped through the region. Temperatures are expected to top out into the upper 80s to lower 90s today. Isolated showers and thunderstorms (15% chance) are possible through the afternoon, decreasing into the evening over the area. Ridge axis stays just west of the area on Saturday, with north to northwest flow and additional energy dropping through the region. Isolated to scattered showers and thunderstorms look to develop over the area for the afternoon and evening hours. With PWATS approaching an inch, thunderstorms will be capable of brief heavy rain both today and Saturday, should you get under one. Highs on Saturday will be similar to Friday, with temperatures in the upper 80s to lower 90s. STP Sunday through Friday... Forecast area will be under the eastern side of the upper ridge on Sunday with weak energy in the flow. Will have ENE flow at the surface helping to bring in some haze/smoke from area wildfires. In addition...pattern supported 20% PoPs E of KBIL with higher PoPs in the mountains due to monsoonal moisture. Blended with SREF to get more PoPs in the forecast than what was shown by the NBM. Still on E side of the ridge on Monday, but models had little in the way of QPF, so mostly dry NBM looked fine. Ridge axis shifts further E on Tuesday and low PoPs over the SW mountains looked good due to monsoonal moisture. Wednesday`s pattern was similar to Tuesday`s with PoPs over the SW mountains. Clusters had varying strengths of SW flow over the western part of the region on Thursday ahead of next Pacific trough. GFS brought a cold front into the area, while ECMWF kept it to the W of the area. NBM brought afternoon/evening 20-30% PoPs into western and central parts of the area. SW flow continued to vary among the Clusters for Friday and NBM had PoPs over the central and W. As for temperatures, Sunday and Monday will be in the mid 80s to mid 90s. Tuesday will be in the 90s. The greatest probabilities for reaching 100 degrees will be on Wednesday and Thursday. Forecast temps will be in the upper 90s to a few degrees above 100 each day. Probabilities for reaching 100 on Wed. were 50-70% in the river valleys, with KBIL at 65%, KLVM at 61%, KSHR at 55% while KMLS was at 36%. On Thu., probabilities were more widespread over the area with 60-80% chances in the river valleys including KLVM, KBIL, KMLS and KSHR. The EFI over the NW half of the area for max temps had .8-.9 on Wed. and .8-.95 for Thursday, which indicated a very unusual to extreme event when related to model climate. There are caveats to this heat forecast, including cold frontal timing and smoke coverage over the area. May need highlights for heat if these temp trends continue, but will have a better idea once these days are closer in time. Regarding fire concerns, Fosberg indices remain low through the period, while Hot Dry Windy increases over the area on Thursday. Again will need to closely watch model trends for later in the period. Arthur && .AVIATION... Isolated showers & weak thunderstorms are diminishing and will end by sunset. VFR conditions under mostly clear skies will persist tonight thru Saturday morning, but another disturbance in northerly flow aloft will bring isolated to scattered thunderstorms by afternoon, beginning around 18z. Local MVFR and erratic wind gusts are possible w/ tomorrow`s storms. Each TAF site is at risk of seeing a TS (20-30% chance). Otherwise, lofted smoke from wildfires will continue to create slant range visibility reductions at times. JKL && .PRELIMINARY POINT TEMP/POPS... Sat Sun Mon Tue Wed Thu Fri ----------------------------------------------------------- BIL 064/092 064/092 064/092 063/097 065/101 067/102 067/097 02/T 20/H 00/U 00/U 01/G 01/G 12/T LVM 055/090 054/090 055/091 055/097 058/099 059/099 058/093 02/T 10/H 00/U 01/U 11/U 12/T 23/T HDN 060/094 059/092 060/093 059/098 061/102 063/104 063/098 23/T 20/U 00/U 00/U 00/G 01/G 11/B MLS 065/091 064/090 064/091 064/095 066/098 066/102 070/097 23/T 22/T 00/U 00/U 00/U 00/G 10/B 4BQ 063/091 063/089 062/090 063/094 065/099 066/102 069/100 23/T 22/T 00/U 00/U 00/U 00/G 00/B BHK 060/090 059/088 059/088 059/091 061/095 063/099 066/097 23/T 22/T 21/U 00/U 00/U 00/U 10/B SHR 056/091 055/088 056/089 055/095 059/098 059/100 062/096 23/T 23/T 01/U 00/U 00/U 01/U 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings