textproduct: Glasgow

KEY MESSAGES

- Cooler than normal temperatures through Thursday, except for a warm and windy day this Tuesday.

- A Lake Wind Advisory is in effect this afternoon/night. Another Lake Wind Advisory is likely needed for tomorrow (Tuesday) as well. The High Wind Watch for Tuesday and Wednesday for SW Phillips County has been upgraded to a High Wind Warning.

- A few isolated thunderstorms are possible south and east of Fort Peck Lake Tuesday afternoon and evening.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Colder air remains in control over the region today as cloudy and mostly cloudy skies gradually begin to clear out this afternoon. ESE winds today will be just enough (15 to 20 mph) to warrant a Lake Wind Advisory, and are expected to linger through the overnight hours (around 20 mph).

Tuesday through Wednesday, a tightly-wound low pressure circulation will sweep down from the Canadian Rockies and through southern Saskatchewan and northeast Montana. The resultant pressure gradient will tighten-up and cause even stronger winds to sweep through the area by way of a cold front. The pre-frontal environment will have just enough warm and unstable air to set off some scattered rain showers and a few isolated thunderstorms, especially south and east of Fort Peck Lake. I chose to upgrade the High Wind Watch for SW Phillips County to a High Wind Warning, but the overall depiction from the model data seems a bit weaker than other recent wind events. At any rate, the downslope areas off the higher elevations of central Montana could see sustained winds around 40 mph with some gusts in excess of 55 mph. I did not see enough model data support to suggest those winds would remain that strong further toward the east. But yes, for Wednesday as well, another Lake Wind Advisory will likely be needed, further out here on the plains.

After the rain showers and thunderstorms diminish toward the east on Tuesday evening, the cold front will quickly drop temperatures back down to near and below freezing for Tuesday night. Some lingering precip would easily change over to snow with some light accumulations possible for locations north of the Hi-Line into early Wednesday morning.

The strong and gusty winds of Wednesday are expected to diminish during the early evening hours, when we will likely be able to cancel all wind headline products. A few lingering snow showers will be possible south of the lake Thursday morning.

Thursday afternoon and beyond, the main passing low pressure system will have moved eastward into the central plains region, and there is some resulting warmer high pressure for us from the south, but it will not be very strong, due to the next low pressure system slowing moving into the US west coast.

Specifics are limited this far out, but that west coast storm system will lead to a generally unsettled and active weather pattern for northeast Montana later this weekend and into early next week.

FORECAST CONFIDENCE & DEVIATIONS:

Blended winds with hi-res models and NBM 90 for today through Wednesday to provide more detail in the expected conditions, particularly with the strong cold frontal passage Tuesday night and climatology support.

There is high confidence in winds meeting Lake Wind Advisory criteria today, with even higher confidence Tuesday night into Wednesday. Confidence is average for high wind criteria to be met in SW Phillips county.

Confidence is also average for the development of isolated thunderstorms Tuesday afternoon over the southern and eastern portions of our CWA.

AVIATION

LAST UPDATE: 1922Z, Monday afternoon Apr 6

FLIGHT CAT RANGE: VFR, with maybe a few passing thunderstorms for KSDY and KGDV Tuesday afternoon.

DISCUSSION: Broken to overcast low to mid-level ceilings today will gradually erode away to mostly clear skies this evening. By Tuesday afternoon, a warm and slightly unstable air mass will be in place to set of a few thunderstorms south and east of Fort Peck Lake and may impact KSDY and KGDV. Amendments may be needed.

WINDS: The approaching low pressure system from the Canadian Rockies, will tighten-up the pressure gradient and funnel stronger winds through NE Montana. Ahead of the cold front, expect winds from the ESE around 15 to 20 kts and gusts up to 30 kts. Behind the cold front afternoon Tuesday night and through Wednesday, expect winds from the WNW around 25 kts with gusts in excess of 35 kts from time to time.

GGW WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory until 4 AM MDT Tuesday for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum.

High Wind Warning from 2 PM Tuesday to 6 PM MDT Wednesday for Southwest Phillips.