textproduct: Great Falls

KEY MESSAGES

- Lull in strong winds during most of the daylight hours on Saturday and Saturday night. - Strong winds again Sunday with high wind warning levels for the Rocky Mtn Front and Northern Plains. - Warm, dry, and breezy through the upcoming work week.

DISCUSSION

- Meteorological Overview:

A weak upper-level ridge is over North-central, Central, and Southwestern Montana. This will allow temperatures to warm up today. Due to a strong surface pressure gradient and strong low-level winds it will be windy across North-central Montana this afternoon through early Saturday morning with the strongest winds along the Rocky Mountain Front and plains west of I-15. This afternoon it will be mostly dry. On Saturday the upper-level ridge strengthens and the strong winds aloft move higher into the atmosphere. This results in warm and dry weather for the area with strong winds ending by mid- morning on Saturday.

On Sunday the upper-level ridge breaks down. This combined with strong low-level and mid-level winds will bring another day of windy conditions to North-central Montana. The strongest winds will be along the Rocky Mountain Front with an extension of strongest winds from favorable mountain wave effects downrange over the northern plains west of I-15. On Sunday it will be dry. On Monday an upper- level ridge moves back over North-central, Central, and Southwestern Montana. This will continue the warm and dry conditions for the area. Tuesday through Thursday the upper-level ridge remains over North-central Montana. This will keep warm and dry weather for the area Tuesday through Thursday. Tuesday through Thursday it will also be breezy across North-central Montana. -IG/RA

- Forecast Confidence & Scenarios:

Early Saturday morning there is a 30 - 60% chance for wind gusts of 70 mph or greater along the Rocky Mountain Front. For winds along the plains west of I-15 this afternoon into Sunday morning there is a 30 - 60% chance for wind gusts of 55 mph along the plains west of I-15. As a result a High Wind Warning was issued for those areas through 9 am Saturday. Across most of the rest of North-central Montana there is a 30 - 60% chance for wind gusts of 55 mph or greater.

On Sunday along the Hi-line east of I-15 and in the lower-elevations of Cascade County there is a 30 - 70% chance for wind gusts of 55 mph or greater. On Sunday along the Rocky Mountain Front there is a 40 - 70% chance for wind gusts of 80 mph or greater. On Sunday across the plains west of I-15 there is a 50 - 90% chance for wind gusts of 70 mph or greater. As a result during the day on Sunday the High Wind Watch for Glacier County, Western Toole County, Pondera County, and the Rocky Mountain Front of Teton and Lewis and Clark Co has been upgraded to a High Wind Warning. Eastern Toole, Liberty, Hill, and Cascade County remain in a High Wind Watch. -IG/RA

AVIATION

07/06Z TAF Period

Gusty winds will continue across the Northern Rocky Mountain Front and High Plains through the first half of the TAF period. Expect low level wind shear across the Northern Rockies through around 16Z. While there is a chance of fog developing early Saturday morning over KWYS, confidence was too low to include in the TAF due to current and projected cloud cover. However, MVFR conditions due to lower ceilings are expected to persist over KWYS through 16Z. VFR conditions will prevail at all other terminals through this TAF period. -Dzomba

PRELIMINARY POINT TEMPS/POPS

GTF 47 63 43 64 / 0 0 0 0 CTB 41 59 36 56 / 0 0 0 0 HLN 35 57 35 62 / 10 0 0 0 BZN 30 56 31 59 / 0 0 0 0 WYS 21 47 22 48 / 0 0 0 0 DLN 29 53 30 57 / 0 0 0 0 HVR 40 62 36 65 / 0 0 0 0 LWT 40 61 39 64 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Warning until 9 AM MST Saturday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Northern High Plains-Southern High Plains.

High Wind Warning from 9 AM to 8 PM MST Sunday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Northern High Plains-Southern High Plains.

High Wind Watch from Sunday morning through Sunday evening for Cascade County below 5000ft-Eastern Toole and Liberty-Hill County.