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Area Forecast Discussion
Issued by NWS Billings, MT
Issued by NWS Billings, MT
732 FXUS65 KBYZ 140259 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 859 PM MDT Sat Jul 13 2024 .UPDATE... Rosebud and Custer county have been removed from the Severe Thunderstorm Watch. Gusts over 70 mph have been recorded from Custer through Fallon and into Carter county so far. Baker gusted to 79 mph from some of the weaker storms in this cluster. Golf Ball hail was reported in northern Rosebud earlier, but most locations have reported 10 minutes or so of less than quarter size hail, though there has likely been much bigger hail in the cores that just didn`t touch a spotter yet. Outflow winds from these storms are moving through Billings right now with gusts in the 30 to 40 mph range expected. Chambers && .DISCUSSION... Through Monday night... Several concerns this forecast period. One was the strong cluster of thunderstorms moving E through S. Saskatchewan. Models varied in their solutions of whether the cluster would impact the eastern forecast area and if it does, they also differed on timing. HREF brings it SE through the area, mostly E of Rosebud County from about 00Z thru 08Z tonight. GFS/WRF keep it NE of the forecast area. ECMWF clips NE zones while weakening the system. If it comes in, HREF showed a few fairly strong helicity tracks and strong wind gusts. KBHK sounding showed 1000-1500 J/kg of MUCAPE and Bulk Effective Shear up to 60 kt, as well as several hundred m2/sec2 of helicity. Thus, if this cluster moves into the eastern zones, strong gusty winds, large hail and a possible tornado would be the main threats. SPC has an enhanced threat area NE of KMLS and over Fallon County. Slight risk includes KMLS and Ekalaka, with marginal further W to Hysham. Given the uncertainty in track, had a 30% PoP over Fallon/NE Custer County through 06Z with 20% PoPs to the S. Kept a 20% PoP over Powder River and Carter Counties after midnight MDT. System pushes a backdoor cold front into the E tonight. Also for late this afternoon through 03Z tonight, monsoonal flow will bring a 20% chance of thunderstorms to the southern mountains and adjacent areas. Included the KBIL area based on CAMS. Low temps will range from the upper 50s W to the mid 60s E. On Sunday, a weak wind shift front will push SE through the area. A cold front will push S through the area Sun. night or Monday. Raised wind gusts toward the NBM 90th percentile Sunday and Monday afternoon into the early evening given good mixing and signals from ECMWF ensemble meteograms. Other forecast concerns included the heat on Sunday and fire weather concerns. High temps will be around 100 degrees with lows in the mid to upper 60s central and E. Heat Advisory was in good shape and set to end Sun. evening. Temps on Monday will be lower...in the upper 80s to around 90 degrees. For fire concerns on Sunday...hot temps and RH`s in the teens, along with gusty winds in the far W and far E are concerning. Fuels are not quite ready in the W. Will have another round of monsoonal thunderstorms over the southern mountains extending to KBIL and KSHR again. HDW showed around a 50% chance of exceeding the 90th percentile over a small portion of the E. Have no PoPs in the east, so will continue the headlines, highlighting the concerns. Monsoonal moisture will affect the area again for Mon. afternoon through Mon. night. Arthur Tuesday through Saturday... Clusters were in good agreement with strong upper ridging prevailing over the region through the extended. Another period of above normal temperatures is in store for the region with highs in the 90s. Chances of temps hitting 100 degrees are 10% or less through Saturday. Period will also be quite dry. PoPs each afternoon and evening were highest in the SW mountains at around 40%. Otherwise had 20% PoPs adjacent to the mountains Chances for QPF reaching 0.10 inches were highest in the high elevations of the SW in the teens to 20%. Fosberg was low thru the period for fire weather concerns. CWASP values for severe potential were also low. Arthur && .AVIATION... VFR conditions will prevail over the next 24 hours with only slight reductions to slant range visibility from smoke. A cluster of thunderstorms, some strong to severe look to track through/near KMLS and KBHK this evening, generally between 01Z to 05Z. With these storms, strong erratic winds and large hail are the main threats, with heavy rain temporarily reducing visibility. Weak showers and thunderstorms also exist along and near the MT/WY border this evening. The main threat with this activity is erratic winds. Sunday will start out quiet before another round of showers and thunderstorms (15-45% chance) moves mainly along the MT/WY border once again. Arends && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 064/100 066/090 063/094 064/094 065/096 065/095 065/094 22/T 20/U 11/U 01/U 11/U 11/B 12/T LVM 058/097 058/092 056/092 056/092 056/094 059/094 058/092 11/B 11/U 12/T 12/T 12/T 12/T 12/T HDN 062/100 064/090 060/095 060/094 061/098 062/097 062/095 22/T 20/U 11/U 11/U 11/U 11/U 11/U MLS 065/099 065/087 061/092 062/089 063/094 065/093 064/092 10/U 10/U 10/U 10/U 10/U 11/U 11/U 4BQ 066/100 069/089 062/092 062/089 063/094 063/093 062/092 30/U 20/B 11/U 11/U 11/U 12/T 11/U BHK 062/098 062/084 057/085 056/086 058/091 060/090 060/090 41/U 10/U 11/U 10/U 10/U 11/U 11/U SHR 060/100 064/089 058/091 055/091 057/093 059/093 059/090 22/T 22/T 22/T 12/T 11/U 12/T 12/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Heat Advisory in effect until 9 PM MDT Sunday FOR ZONES 29>34-36-37-40-42-56>58-63>66-138-139-141-169-170-172-173-228-235. Severe Thunderstorm Watch 525 in effect until midnight MDT tonight FOR ZONES 33-36-37. Red Flag Warning in effect until midnight MDT tonight FOR ZONE 117. WY...Heat Advisory in effect until 9 PM MDT Sunday FOR ZONE 199. && $$ weather.gov/billings