textproduct: Great Falls

KEY MESSAGES

- Scattered showers and isolated thunderstorms late this afternoon into overnight hours, mainly SW MT.

- Above average temps through Friday.

- Upper level trough will bring cooler and windier weather during the upcoming weekend.

DISCUSSION

- Meteorological Overview:

An upper level ridge will allow for above average temps and southwesterly flow to persist across MT through Friday. Due to an upper level disturbance, there will be scattered showers and weak thunderstorms late this afternoon into the overnight hours, mainly impacting SW MT. Additionally, high clouds will continue to spread northward as the day progresses. Warm temperatures will peak for most of MT on Thursday and Friday. Although temps will be above average for this time of year, they will remain well below record levels. ESH

A relatively strong Pacific cold front is forecast to traverse the northern Rockies late Friday into Friday night. However, model discrepancies persist regarding the precise timing and intensity of the embedded shortwave as it lifts northeastward from the Northern Rockies into AB by Saturday morning. Gusty southwest winds are likely to precede the front late Friday with showers and potentially some thunderstorms accompanying the frontal passage, followed by gusty west winds and cooler temperatures for the weekend. Hoenisch

- Forecast Confidence & Scenarios:

Due to cape values remaining mainly under 500 J/kg, thunderstorm threats will be primarily limited to isolated lightning strikes and brief gusty winds this afternoon and evening.

Looking towards the weekend, the main concern will be stronger winds along the Rocky Mountain Front and adjacent areas Friday afternoon through Saturday morning due to the approaching upper level trough and cold front. Strongest winds for the Rocky Mountain Front are currently expected Friday night with a 30-40% chance of gusts 55 mph or above. During that same time frame, there is a 10-20% of gusts exceeding 70 mph. ESH

AVIATION

22/18Z TAF Period.

Initial concern this TAF period will be for scattered showers and thunderstorm late afternoon and through the evening across Southwest Montana and vicinity. Briefly gusty winds would be the greatest concern from thunderstorms that do form. Attention then turns to the risk for some patchy fog by Wednesday morning in Southwest Montana valleys, particularly in areas that end up seeing precipitation today. Breezy winds develop in many areas over the plains Wednesday by late morning. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 52 79 50 84 / 0 0 0 0 CTB 48 73 46 78 / 0 0 0 0 HLN 50 77 47 82 / 10 0 0 0 BZN 48 73 45 79 / 20 0 0 0 WYS 36 64 30 71 / 60 10 0 0 DLN 44 73 42 77 / 40 0 0 0 HVR 50 80 48 84 / 0 10 0 0 LWT 51 76 49 82 / 20 10 0 0

TFX WATCHES/WARNINGS/ADVISORIES

None.