textproduct: Great Falls

KEY MESSAGES

- Windy at times today through Monday.

- Increasing chance for showers and thunderstorms this afternoon into this evening.

- Cooler afternoon temperatures early this week will give way to warmer and drier conditions next weekend.

DISCUSSION

- Meteorological Overview: A closed upper level low is approaching Montana from the west this morning. Thus expect increasing clouds this afternoon, along with increasing chances for showers/thunderstorms by this evening. The heaviest precipitation will generally fall over North Central MT tonight. Colder temperatures will also move into the CWA, with the Glacier Park area seeing the coldest temperatures. Rain will change to snow for elevations above 6500 feet overnight, with some snow accumulations at ridge tops. This system exits the CWA on Monday, with showers decreasing during the afternoon.

Generally dry and stable conditions are expected from Tue through Thursday, along with a slow warming trend during this period.

On Friday, a quick moving closed upper level low will move from west to east across Southern MT. This will result in a good chance for precipitation over Southwest MT by Friday. At this time, most of the precipitation will fall as rain, and since it will be quick moving, heavy precipitation is not expected at this time.

Looking ahead to next weekend, generally dry and warm conditions are expected for next Sat/Sun, as a quick building upper level ridge of high pressure is forecast to build over the northern Rockies.

- Forecast Confidence & Scenarios: The main concern for later today and tonight will be thunderstorm potential over the Plains and snow over the Rockies.

The airmass will become unstable by this afternoon, with the HREF forecasting a strong storm developing between Great Falls and Havre between 5 PM and 8 PM this evening. Hail and strong wind gusts will be the main impact from this storm. Additional thunderstorms are possible a bit further east this evening as the entire disturbance starts to shift to the east.

Overnight, the concern shifts to the Rocky Mountain Front in terms of how low do snow levels get by Monday morning. The current freezing level aloft is near 11,000 feet, so it will take some time for the air to cool this evening. That being said, by Monday morning, snow levels could fall down to about 6500 feet over the Rocky Mountain Front, including the Glacier Park area. Snow accumulations of a few inches are possible above 7000 feet. No winter weather advisory for snow will be issued at this time.

There continues to be near a 70 percent chance for strong winds today from Ennis to Norris Hill. It is looking like sustained winds for an hour or so might be the bigger impact. Thus a high wind warning has been issued for this area.

For Monday, there continues to be about a 60 percent chance for strong winds over Judith Basin and Fergus counties. Thus the high wind watch over Central MT was expanded to include Judith Basin County for Monday. Brusda

AVIATION

13/12Z TAF Period.

Morning low clouds will give way to increasing chances for showers/thunderstorms this afternoon and evening. Some storms could be on the strong side this evening over North Central MT. Otherwise gusty afternoon winds will decrease for a short time overnight. Showers decrease during the day on Monday. Mountains/passes will be obscured at times across the CWA through the period. Brusda

FIRE WEATHER

A red flag warning has been issued for portions of Southwest MT for low humidity and gusty winds for today. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 68 45 62 41 / 10 70 20 0 CTB 59 41 57 39 / 40 20 40 20 HLN 71 43 63 39 / 20 50 10 0 BZN 78 38 62 33 / 0 70 10 0 WYS 69 26 59 23 / 0 20 0 0 DLN 75 36 63 32 / 0 10 0 0 HVR 71 45 62 39 / 0 90 50 10 LWT 72 40 57 36 / 0 40 30 10

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Watch from Monday morning through Monday afternoon for Fergus County below 4500ft-Judith Basin County and Judith Gap- Snowy and Judith Mountains.

High Wind Warning from noon today to 6 PM MDT this evening for Madison River Valley.

Red Flag Warning for portions of Southwest MT for today.