Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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198 FXUS65 KTFX 111745 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1145 AM MDT Tue Jun 11 2024 Aviation Section Updated .SYNOPSIS... Dry and breezy to windy conditions are expected over the next couple of days while temperatures generally run above average. Another Pacific disturbance will move through the Northern Rockies this weekend, initially bringing scattered showers and thunderstorms followed by cooler and windy weather. && .UPDATE... No real update to report on, the going forecast remains on track. -thor && .AVIATION... 11/18Z TAF Period VFR conditions will prevail across the region through the period. Expect increasing winds this afternoon over North Central MT, with the windy conditions continuing into Wednesday. The Chinook arch is currently breaking down, with generally just passing mid/high level clouds expected through the period. Brusda Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 510 AM MDT Tue Jun 11 2024/ Dry and breezy conditions are expected for much of today while shortwave ridging passes through the region. A Pacific cold front crosses the Continental Divide late in the afternoon and may bring a few isolated showers and thunderstorms as it quickly races eastward during the evening hours. Strong westerly flow aloft associated with a trough moving through Southern Canada will then increase surface winds along the Rocky Mountain Front tonight. Projected H700 to H500 flow has increased some and looks to run between 45 and 55 kts or around 3 standard deviations above climatology according to the NAEFS (North American Ensemble Forecast System), though peak flow most likely to occur during the overnight hours will at least limit the overall coverage of higher end gusts. With that in mind, forecast soundings do show profiles conducive for mountain wave activity along the Rocky Mountain Front and adjacent high plains for increased chances for wind gusts exceeding 55 mph during the nighttime hours. Deep layer mixing then encourages the windy conditions to move eastward into the plains and valleys. Current wind exceedence probabilities for this event suggest that peak wind gusts will mostly fall between the 35 and 55 mph range for most locations except along the Rocky Mountain Front and adjacent high plains where gusts up to and exceeding 60 mph will be more common. The primary concern continues to be difficult conditions for summer outdoor recreation and travel; however, afternoon temperatures in the 70s and 80s combined with the said winds and minimum relative humidity values in the teens and 20s is expected to accelerate the curing/drying of grassland fuels. While no fire products are anticipated this time around, this drying process may set up fire weather concerns in the future. Another brief period of transient ridging aloft will bring calmer winds and continued dry conditions for Thursday and much of Friday before another Pacific trough brings unsettled conditions next weekend. Although uncertainty remains with the specifics of this system, most ensembles favor the primary circulation and moisture staying north in Canada, which reduces the likelihood for widespread rainfall for North-central and Southwest Montana. The first opportunity for precipitation comes later Friday into Saturday when southwesterly flow and a cold frontal passage encourage a period of shower and thunderstorm development. Breezy to windy conditions and cooling temperatures are then expected for the remainder of the weekend with another chance for scattered showers late Sunday into Monday. - RCG && .PRELIMINARY POINT TEMPS/POPS... GTF 85 50 77 42 / 0 10 0 0 CTB 82 46 71 40 / 0 0 0 0 HLN 87 53 82 46 / 0 10 0 0 BZN 85 49 83 42 / 10 10 0 0 WYS 75 42 77 37 / 10 10 0 0 DLN 83 48 81 43 / 0 10 0 0 HVR 87 54 78 44 / 0 20 0 0 LWT 82 48 75 42 / 0 40 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls