Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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665 FXUS65 KTFX 260910 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 310 AM MDT Thu Sep 26 2024 .SYNOPSIS... Breezy to windy conditions and seasonably mild temperatures are expected for the next day or so before brief warming takes place for the first half of the weekend ahead of the next weather system. The aforementioned system will bring another brief cool down, slight chances for showers, and more breezy to wind conditions for Sunday and Monday. && .DISCUSSION... An initial wave of stronger winds, with gusts in the 40 to 55 mph range, moved through the Northern Rocky Mountain front and nearby high plains earlier tonight. Wind speeds have leveled off since then, but a stripe of 40 to 50 kt H700 winds arrives for another opportunity for strong surface wind between now and 29/16Z. Then winds aloft relax and diurnal mixing takes over and maintains windy conditions in the aforementioned areas through this afternoon. Given the anticipation of a second wave of winds, I will leave the High Wind Warning as is for now. Other plains locations will see elevated westerly winds as well, but wind gusts will mostly remain in the 25 to 45 mph range. Temperatures in the wake of the front will cool closer to the seasonal average for this time of year. Similar conditions are expected on Friday as westerly flow aloft remains elevated, but the lack of cold air advection and shortwave energy will result in overall lighter wind speeds and warmer temperatures than today. Ensembles generally favor a continued progressive west to southwesterly flow aloft this weekend into early next week, though there are still differences among members in regards to the timing of passing shortwave disturbances. Overall, this looks to result in temperatures oscillating from near average to above average and back again, along with periods of breezy to windy conditions. I maintained the NBM solution which features frontal passages and associated cool downs/windier periods and slight chances for showers Sunday into Monday and again Tuesday into Wednesday. - RCG && .AVIATION... 26/06Z TAF Period VFR conditions are forecast to continue across North Central (KCTB, KHVR), Central (KLWT, KGTF, KHLN), and Southwest (KBZN, KEKS, KWYS) Montana through at least 27/06Z. However, precipitation along the Continental Divide from the Canadian border south to northwest of KHLN may obscure mountain tops there through around 15Z. The main concern during this period will be the winds. A passing Pacific cold front ahead of a shortwave trough will cause gusty southerly winds to shift more westerly and increase through around 12Z or so from west to east. Most areas will see gusts in the 20 to 30 kt range with widespread mountain wave turbulence and areas of low level wind shear. However, the strongest winds will be on the Rocky Mountain Front and adjacent plains, where winds could be sustained between 20 and 30 kt with gusts potentially in excess of 50 kt at times. Increased high- and mid-level cloudiness is also expected during this time. Winds and clouds are forecast to decrease from west to east after 20Z or so as the shortwave exits the area. -Coulston Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 72 49 81 46 / 0 0 0 0 CTB 64 46 74 41 / 10 0 0 0 HLN 76 48 82 49 / 0 0 0 0 BZN 78 43 82 44 / 0 0 0 0 WYS 71 33 73 33 / 0 0 0 0 DLN 75 42 80 44 / 0 0 0 0 HVR 71 45 82 46 / 10 0 0 0 LWT 71 45 80 47 / 0 0 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 3 PM MDT this afternoon for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Eastern Toole and Liberty-Northern High Plains-Southern High Plains-Southern Rocky Mountain Front. && $$ http://www.weather.gov/greatfalls