textproduct: Great Falls

KEY MESSAGES

- Strong and gusty winds along the Rocky Mountain Front through Wednesday.

- Above normal temperatures for most locations.

- Staying dry through Wednesday.

DISCUSSION

- Meteorological Overview:

H500 ridge over the western half of the CONUS and Canada early this morning will largely remain in place through the remainder of the work week, with the ridge axis gradually shifting eastward and over the Northern Rockies from late Thursday through early Saturday as longwave troughing begins to dig south over the Eastern Pacific. As this ridge axis shifts east over the Northern Rockies through the second half of the work week the surface pressure gradient along the Rocky Mountain Front, Island Ranges of Central Montana, and north- south valleys of Southwest Montana will gradually begin to relax, which will help to support "lighter" winds across the locations. However, prior to this occurring continued strong and gusty south to west winds will persist due to periods of moderate to strong pressure gradients, most notably from the East Glacier Glacier Park Region to the Northern High Plains.

Temperatures will continue to run above to well above normal beneath the ridge through the rest of the work week across much of Southwest through North Central Montana, with the exception of areas northeast of a Shelby to Fort Benton line where near normal temperatures are expected thanks to a series of weak backdoor cold front pushing southwest from Saskatchewan. Overall dry conditions will continue to hold strong through Wednesday night, with a gradual increase in precipitation chances over the mountains of Southwest Montana and along the Continental Divide from Thursday through the first half of the upcoming weeekend. - Moldan

- Forecast Confidence & Scenarios:

High Winds along the Rocky Mountain Front...

A moderate to strong pressure gradient will continue to reside along the eastern foothills of the Continental Divide over North Central Montana through the day on Wednesday, with the gradient peaking at times near 0.2mb/km from this evening through early Wednesday morning over the East Glacier Park Region, Northern High Plains, and northern sections of the Southern Rocky Mountain Front and Southern High Plains. While BUFKIT sounding for the Marias Pass and Cut Bank Areas support ideal thermal profiles for mountain wave activity during this timeframe they largely lack the desired cross barrier flow of greater than 50kts to support High Wind highlights. None-the- less, the aforementioned pressure gradient of 0.2mb/km is impressive in itself and any additional enhancement from a breaking mountain wave could help to support periods of strong gusts and/or sustained winds, especially in-between the Badger Creek and Two Medicine River valleys. NBM4.3 probabilities for gusts in excess of 64kts for these locations is generally around a 10% chance from the evening hours tonight through early Wednesday morning, with a 10-15% chance for sustained wind speeds in excess of 43kts. Given that model guidance underperforms at times in instances of strong pressure gradients I've elected to issue a High Wind Watch for the East Glacier Park Region, Northern High Plains, and Eastern Glacier/Western Toole/Eastern Pondera Counties from 03z Wednesday through 15z Wednesday. - Moldan

AVIATION

30/06Z TAF Period

VFR conditions prevail through the TAF period. There will be broken mid to high level clouds overnight, clearing throughout the day Tuesday. - Wilson

PRELIMINARY POINT TEMPS/POPS

GTF 47 33 52 28 / 0 0 0 0 CTB 45 28 48 24 / 0 0 0 0 HLN 40 19 44 31 / 0 0 0 0 BZN 40 16 45 25 / 10 0 0 0 WYS 33 2 38 12 / 10 0 0 0 DLN 41 22 45 29 / 10 0 0 0 HVR 35 20 34 15 / 0 0 0 0 LWT 48 29 54 30 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Watch from this evening through Wednesday morning for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Northern High Plains.