textproduct: Great Falls

KEY MESSAGES

- Higher terrain snow will continue in Southwest Montana through this morning.

- Consistent rainfall will continue today across Southwest, Central, and North-Central Montana, decreasing tonight before dissipating early tomorrow morning.

- Daily chances for showers and thunderstorms throughout the rest of the week.

DISCUSSION

- Meteorological Overview:

A large upper level trough with multiple embedded upper level lows will continue to create impactful weather across the CWA today. Northerly to northeasterly winds through the lower to mid- levels will combine with forcing from the troughing across the region to result in continued widespread precipitation today. This stratiform rain will persist through tonight into early tomorrow morning. Mountain snow will continue in Southwest Montana through late this morning. Precipitation amounts look greatest near Glacier NP, where northerly to northeasterly mid- level will be most orthogonal to terrain. Those with interests in and near Glacier NP should be aware of the risk for rockfall and creek and stream rises through tomorrow morning.

The upper level trough moves out of the CWA tomorrow, ending the persistent stratiform rain. However, there will be daily chances for showers and thunderstorms throughout the rest of the week, as instability in the atmosphere persists. Despite this, shear remains low at this time, inhibiting the development of severe thunderstorms. Temperatures will have a warming trend, peaking early next week with highs in the mid to high 80s with the building of an upper level ridge. - AM and Dzomba

AVIATION

29/06Z TAF Period

Widespread rain and high mountain snow will affect much of the CWA through the period. Expect the precipitation to slowly begin to diminish after 00z Tue over Southwest MT and the eastern portions of the CWA. Strong surface winds over North Central MT should decrease a bit by 12z Mon. Mountains/passes will be obscured across the CWA through the period. Brusda

HYDROLOGY

Periods of rain will continue to affect the CWA from today through Monday. Widespread rainfall amounts of 1 to 3 inches are still expected by Monday.

In the Glacier Park region, rainfall is expected to be a bit heavier, possibly up to 4 inches. Additionally, with some high elevation snow still left, the combination of rainfall/snowmelt could lead to some flooding on the east side of Glacier National Park. Thus a flood watch has been issued for this region starting on Sunday. Should later forecast today decrease the projected rainfall amounts, the flood watch might be cancelled.

Additional flood statement might be needed if rainfall amounts start to exceed 3 inches elsewhere across the CWA. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 44 58 50 74 / 100 100 90 20 CTB 47 60 49 71 / 100 90 90 20 HLN 44 58 49 72 / 100 100 80 50 BZN 39 54 44 71 / 100 100 70 30 WYS 28 47 32 63 / 90 100 50 10 DLN 36 55 40 68 / 100 100 30 50 HVR 45 63 50 76 / 90 80 70 40 LWT 41 54 45 70 / 60 100 80 40

TFX WATCHES/WARNINGS/ADVISORIES

Flood Watch through Monday evening for East Glacier Park Region.

High Wind Warning until 3 AM MDT Monday for Bears Paw Mountains and Southern Blaine-Hill County-Western and Central Chouteau County.

Winter Weather Advisory until noon MDT Monday for Elkhorn and Boulder Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Ruby Mountains and Southern Beaverhead Mountains.

Winter Storm Warning until noon MDT Monday for Northwest Beaverhead County.