textproduct: Great Falls

KEY MESSAGES

- Periods of rain/snow/isolated thunderstorms will continue into Wednesday.

- Below normal temperatures will continue through Wednesday as well.

- Temperatures might go above normal by Friday, but cooler temperatures and a chance for showers return by Sunday.

UPDATE

425 AM Update...Updated morning forecast to increase pops over Chouteau County early this morning. A band of snow has set up, mainly between Fort Benton and Box Elder. This band of snow should start to decrease after 6 AM. Brusda

DISCUSSION

- Meteorological Overview: A slow moving upper level low over central Canada, with a large circulation, will continue to affect the weather over the CWA for the next several days. Cool air aloft, combined with daytime heating will allow for scattered rain/snow showers to develop daily through at least Wednesday. The overall precipitation amounts will be on the light side, but some short periods of accumulating snow are likely through Monday. There will be just enough instability during the afternoon hours that some isolated lightning strikes will also be possible. Overall, below normal temperatures will continue daily through Wednesday, with today and Monday being the coolest days.

For Thursday through Sunday...the upper level low in Canada will move off to the east, as a new upper level trof begins to move southward along the Pacific coast by Saturday. This trof will influence the weather over our CWA, with a moist southwesterly flow aloft developing. This will result in warmer air pushing northward into the CWA, but also allow for scattered showers or event a thunderstorm to move back into the CWA by Sunday.

- Forecast Confidence & Scenarios: The winter weather advisory will continue through the morning hours over the Northern Rockies and in the Browning area.

Another round of light snow will affect the Central and Southern portions of the CWA tonight into Monday. At this time, I only have about an inch or two of snow accumulations on the mountain passes, thus holding off on an advisory for now. It is looking more likely that an SPS will be needed for Sunday night into Monday. Brusda

AVIATION

26/12Z TAF Period

Scattered snow showers will continue to affect the CWA through the period. In terms of affecting a terminal, the probability still remains low, but can't be ruled out. Overall the probability of visibility below 1SM is on the low side for more than 2 hours. Mountains/passes will be obscured at times across the CWA through the period. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 38 22 48 28 / 50 20 30 10 CTB 34 13 46 22 / 60 10 10 0 HLN 42 24 49 28 / 40 30 50 10 BZN 46 25 46 25 / 40 50 70 20 WYS 44 20 43 20 / 70 70 80 40 DLN 49 27 47 27 / 30 50 60 10 HVR 41 18 48 25 / 30 10 10 10 LWT 38 20 43 23 / 50 40 50 20

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until noon MDT today for East Glacier Park Region-Northern High Plains.