textproduct: Glasgow

KEY MESSAGES

- Gusty winds will veer W-NW by early this morning.

- Possible rain showers in the southeast portions of the CWA Sunday afternoon and evening. Isolated Thunderstorms may be possible SE of the Yellowstone River.

DISCUSSION

An upper-level trough is currently over the PNW. Embedded within the trough is a shortwave digging over the Northern Rockies and Great Plains region. A front associated with the shortwave is passing through NE Montana, causing a decrease in temperatures and gusty winds to veer W-NW early today. A Lake Wind Advisory is currently in effect until today at 9AM.

The shortwave and associated front exit to the east by late this morning ahead of the main trough, which will begin digging over the Northern Rockies this afternoon. From here, the trough will stall and remain quasi-stationary due to an omega blocking pattern currently developing over the Midwest and Great Lakes regions.

By Sunday afternoon, the omega block will have decayed and the upper-level trough over Montana will begin exiting to the NE, leaving moisture-ladden SW flow aloft in its wake. Isolated pockets of vorticity may generate rain showers in the southeast portions of the CWA Sunday afternoon and evening. Isolated Thunderstorms may be possible SE of the Yellowstone River.

SW flow aloft will gradually flatten and become semi-zonal over the course of Monday, becoming truly zonal by Tuesday afternoon. Fair conditions will persist through the week.

FORECAST CONFIDENCE & DEVIATIONS:

Confidence in rain showers Sunday is low. Precipitation could easily occur in the western portions of North Dakota, rather than within our CWA. Wetting rain is unlikely.

DON

AVIATION

LAST UPDATED: 0720Z

FLIGHT CAT RANGE: VFR

DISCUSSION: Skies becoming fair with FEW/SCT clouds at variable heights. No ceilings are expected to redevelop within the next 24 hours.

LLWS: Chances (50-60%) for low-level wind shear across the region until 14Z due to a developing low-level jet. Confidence is high enough to include LLWS in the TAFs at KSDY, KGDV, and KOLF.

SFC WIND: W-NW at 15 to 25 kt with gusts to 30 kt, reducing to 10 to 20 kt with gusts to 25 kt by this morning. Winds will decrease in strength further to about 10 kt by Saturday evening.

GGW WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory until 9 AM MDT this morning for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum.