Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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214 FXUS65 KTFX 041644 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1044 AM MDT Tue Jun 4 2024 .SYNOPSIS... Very windy conditions continue through tonight across the area with strong winds becoming more widespread across north-central and central Montana this afternoon and evening. Winds gradually decrease on Wednesday with warmer and drier conditions following through the rest of the week. && .UPDATE... Just a few minor tweaks to the forecast this morning. I blended in some Hi-Res guidance to account for some higher than forecast wind gusts across the North Central Plains in the hourly forecasts that had been occurring and brought the hourly temperatures into better alignment with observations. Ludwig && .AVIATION... 04/12 Z TAF Period Except for some showers early this morning near KHVR and through this evening along the continental divide, VFR conditions prevail with strong westerly flow aloft and at the surface being the primary impact to aviation through tonight. Mountain wave turbulence will be a hazard across much of the area through the period with low level wind shear possible in some areas this morning where winds are lighter at the surface but especially tonight as the strongest winds aloft move across the area during the overnight period. Surface wind gusts in excess of 40kts expected at most terminals this afternoon with periodic gusts in excess of 50kts at KCTB and higher gusts along the east slopes of the Rockies and central/north-central MT mountain ranges. Hoenisch Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 530 AM MDT Tue Jun 4 2024/ A compact mid level low and surface low pressure located in SW Saskatchewan this morning will lift slowly northeast today while an unusually strong upper level jet is streaming across the Northern Rockies with highest speeds still offshore (130-140kt) streaming east roughly along the US/Canadian border tonight. All of this translates to a continuation of very windy conditions for the area through the next 24 hrs with a peak in wind intensity this morning, decreasing somewhat around mid-day before intensifying again late this afternoon through this evening. Except for some showers circulating around the mid level low this morning across Hill and Blaine counties and showers at times near the continental divide through tonight, most of the area will see dry conditions and temperatures slightly cooler than average with wind being the primary weather impact through tonight. Strong wind gusts (in excess of 55 mph) early this morning are primarily confined to mountain wave enhanced areas along the Rocky Mtn Front and N/E slopes of the north-central MT mountain ranges, however 35-45 mph gusts are common outside of this area across central/north-central MT and across the higher terrain of southwest MT. General wind flow across the area decreases slightly later this morning into early this afternoon before increasing significantly late this afternoon through this evening. Within the overall larger wind maximum, an area of 70-80kt 700MB wind speeds is supported by most models across central MT this evening. Wind speeds of this magnitude are highly unusual for early June and at least locally above the 99th climatological percentile per ECMWF/NAEFS ensembles. No changes were made to the High Wind Warning overnight, which expands to cover remaining portions of north-central MT later this morning and continues through tonight. While strong wind gusts will likely have the greatest coverage across the area late this afternoon and evening, the highest gusts may continue through the overnight period in mountain wave enhanced areas downwind (east/northeast) of the Southern Rocky Mountain Front and Little Belts. Winds decrease on Wednesday with a quieter and warmer period of weather developing as upper level ridging gradually amplifies across the Western US into the upcoming weekend. Temperatures warm above seasonal averages beginning Thursday and are likely to remain above average well into next week with upper level ridging over the Western US supported by most longer range model ensembles. Moisture circulating around the ridge gradually creeps into the area from the SW as early as Friday afternoon and moreso through the weekend for some isolated diurnal shower/thunderstorm possibilities, initially across southwest MT. There is some indication of a more substantial push of moisture and shortwave moving over the ridge in the Sunday/Monday timeframe for more widespread shower/thunderstorm potential. Hoenisch && .PRELIMINARY POINT TEMPS/POPS... GTF 68 47 71 43 / 10 10 0 0 CTB 61 43 67 40 / 0 0 0 0 HLN 70 50 76 48 / 10 10 0 0 BZN 69 49 76 44 / 10 10 0 0 WYS 61 43 73 40 / 10 10 0 0 DLN 68 48 77 45 / 10 10 0 0 HVR 72 48 71 43 / 0 0 0 0 LWT 68 46 67 42 / 10 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning until noon MDT Wednesday for Bears Paw Mountains and Southern Blaine-Big Belt, Bridger and Castle Mountains-Cascade County below 5000ft-East Glacier Park Region- Eastern Glacier, Western Toole, and Central Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Fergus County below 4500ft-Hill County-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Meagher County Valleys- Northern Blaine County-Northern High Plains-Snowy and Judith Mountains-Southern High Plains-Southern Rocky Mountain Front- Upper Blackfoot and MacDonald Pass-Western and Central Chouteau County. && $$ http://www.weather.gov/greatfalls