textproduct: Glasgow

KEY MESSAGES

- Warm, dry, and gusty conditions this afternoon will be monitored for any fire weather concerns. Conditions are also just short of Lake Wind Advisory and this will be monitored for as well.

- The first major frost of the season is possible along river bottoms Thursday morning, due to cooler surface temperatures associated behind a cold front.

- There is a small chance for isolated shower or thunderstorm Friday afternoon and evening. Totals do not look significant.

DISCUSSION

Synoptic Setup: Forecast begins with zonal flow running from off the coast of the Pacific Northwest through the PCNW and Montana. North of this is cooler air at the surface embedded in a broad trough over southern Canada that has leaked down into the Plains and northeast Montana. To the south a large closed low sits over the Four Corners with a ridge just west of it running north from the Baja and cresting over northern California.

Today into tonight: Zonal flow across the region will have weak embedded disturbances in the flow that form a modest pressure gradient force across the region today. This will lead to breezy west winds in the afternoon which look to be just short of a Lake Wind Advisory. While it currently doesn't look to be strong enough it will need to be monitored for a last minute uptick. In this same vein, downslope wind will generate lower RH across the region and if winds were to tick up quite a bit above expected totals then Fire Weather concerns could quickly rear their ugly head as well. Wind speeds and gusts will need to be monitored through the day.

Wednesday into Friday: As the Four Corners low migrates east onto the Plains, the ridge behind it will widen out along the Intermountain West and begin bumping up against the PCNW/MT Zonal flow and begin constricting and orienting it to a more NW flow pattern. The constriction will allow some lift zones to show up which could lead to little sub-synoptic disturbance for isolated chances at showers and thunderstorms as they pass by northeast MT during these times. Though, QPF totals look minimal if anything more than a trace.

Friday night onward: Northwest flow will continue to enhance as the ridge rides up into the PCNW and southern British Columbia. This will make conditions mostly dry into the Weekend. With significant model breakdown beginning around Sunday/Sunday night into early next work week.

FORECAST CONFIDENCE & DEVIATIONS:

- Moderate confidence in winds this afternoon staying below Red Flag or Lake Wind Criteria.

- Low to Moderate confidence in chances for isolated showers Wednesday through Friday.

- Moderate confidence in partial frost Thursday morning.

GAH

AVIATION

LAST UPDATED: 0430Z

FLIGHT CAT RANGE: VFR

DISCUSSION: Cirrus clouds overhead KGGW, KGDV and KSDY with clearing by this evening. VFR conditions prevail through Tuesday night.

FOG: There is a small chance (10-30%) for fog to sneak in from North Dakota along valley bottoms and impact KSDY and KOLF. but it's too low a chance to place in the TAFs directly. If this were to occur it would occur with the time frame of 10 to 14Z and then be done.

LLWS: Low level wind shear is possible at KGGW and KOLF from 03-12Z Tuesday night.

SFC WIND: Light and variable winds through sunrise. Becoming SW to W and increasing to 10 to 20 kts gust 25 kts int he afternoon. Calming to 5 to 10 kts in the evening Through Tuesday night.

FINDLEY/GAH

GGW WATCHES/WARNINGS/ADVISORIES

None.