Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
731 FXUS65 KBYZ 231952 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 152 PM MDT Sun Jun 23 2024 .DISCUSSION... Today through Monday night... The hottest day of the year so far is well underway. Several locations have already surpassed 90F and Sheridan, WY just hit 100F for the first time since July 24, 2023. Locations in the Yellowstone River Valley likely (50-80%) to reach 100F this afternoon. One inhibiting factor to these locations reaching 100F would be the lack of mixing out of a persistent easterly wind. A weak shortwave and associated cold front will move across the area late this afternoon/early evening, bringing a wind shift to the northwest and isolated to scattered high-based convection (up to a 25% chance, greatest over in northern Musselshell and Rosebud Counties). While there is a Marginal Risk for Severe Thunderstorms in the northern counties, most models have shown an environment that will struggle to produce a strong to severe storm along and north of US Highway 12. The extent of the warm temperatures seems to be a limiting factor in storm development with dew point depressions of 20-30F. However, there is modest instability across much of the area with MUCAPE values in the 1000-2000 J/kg range and deep layer shear up to 50 knots. The strongest of any storm(s) today would be capable of producing heavy rain, gusty winds, and hail. In the wake of the frontal passage, high temperatures on Monday will be much cooler, in the 80s to near 90F. With zonal flow in the mid levels, some weak energy moves through tomorrow afternoon, bringing a low chance for a shower or thunderstorm in the Absaroka/Beartooths. Some gusty winds in the 20s-30 mph are forecast in the western areas tomorrow as well. By tomorrow evening, this weak energy will move over the far east bringing the chance for an isolated shower or thunderstorm. Overnight lows will be warm tonight, in the 50s to mid 60s. Cooler lows Monday night, in the 50s. Matos Tuesday through Sunday... Tuesday should be dry under rising heights, with highs in the 80s, and a shift to N-E winds courtesy of a passing shortwave thru AB/SK...though cannot completely rule out some late day weak convection/virga/moderate cumulus over the southern mountains. Temps will jump to the mid 80s to lower 90s Wednesday as the ridge axis begins to shift east, allowing for warmer air from the southwest. The backing flow will also introduce at least a low (20%) chance of late afternoon convection over our southwest mountains and foothills, perhaps spreading over some lower elevations that evening. Some uncertainty exists here, but it should be noted that in addition to advection of plains moisture from southeast winds, the SW flow aloft is expected to bring a component of monsoon moisture. Ensembles suggest pwats rising to near an inch, plenty for some high-based convection. Something to keep an eye on. The greater chance (30-50%) of showers/thunderstorms is Thursday as a fairly deep (for late June) Pacific trof moves into the northern Rockies, offering ascent along with existing instability. Would expect wind shear to be sufficient for a risk of severe storms, but a big factor may be the timing of a Pacific fropa. At the very least, there is a risk of strong/severe storms in our east. Upper trof swings thru for a continued chance of showers and weaker thunderstorms on Friday, along with a dose of cooler air. After highs ranging from the upper 70s to lower 90s Thursday, Friday should see upper 60s to mid 70s most places. Precip-wise, other than locally higher amounts w/ convection, most places will see a third of an inch or less of rain. The probability of 0.50" in the 48-hr period ending Friday night is only 10-30%, highest over the western mountains. Finally, cannot rule out some light snow showers over the high elevations (>10kft) of the western mountains by late Thursday night as 700mb temps could fall to near zero. Upper level ridge will build back from the west yielding dry wx Friday night thru Sunday morning. By late Sunday the next Pacific shortwave will arrive bringing the next chance of showers & thunderstorms. This may signal the beginning of a few days of lower heights in WNW flow aloft (i.e. unsettled weather) the first half of the following week. JKL && .AVIATION... There is a low chance for isolated high-based showers and thunderstorms this afternoon from KLVM to KMLS and north affecting KMLS after 00Z. Gusty winds up to 35 kts are possible with any thunderstorm. VFR conditions will prevail through the forecast period. Matos/TS && .PRELIMINARY POINT TEMP/POPS... Mon Tue Wed Thu Fri Sat Sun ----------------------------------------------------------- BIL 061/089 057/086 058/090 063/090 055/071 049/078 053/086 20/U 00/U 00/U 24/T 53/T 10/U 01/U LVM 055/089 050/088 052/089 056/084 046/068 042/077 049/082 11/N 00/U 02/T 24/T 44/T 10/U 02/T HDN 060/089 055/087 055/093 060/091 053/072 046/080 053/089 20/U 00/U 10/U 13/T 43/T 10/U 01/U MLS 065/086 057/084 056/089 065/090 056/073 049/077 055/087 20/U 00/U 00/U 22/T 52/T 21/U 01/U 4BQ 067/088 059/087 056/091 063/094 056/074 049/077 055/089 00/U 10/U 00/U 12/T 42/T 20/U 01/U BHK 063/085 054/084 052/086 061/090 055/072 046/075 050/084 10/U 10/U 01/U 12/T 52/T 21/U 11/U SHR 060/091 055/086 053/091 058/090 051/072 044/079 051/089 01/U 00/U 00/B 12/T 22/T 10/U 01/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings