textproduct: Glasgow

KEY MESSAGES

- Some isolated patchy fog is possible across the Yellowstone Valley this morning.

- A slow warm up with mostly dry conditions is expected Today through Thursday.

- Another system will arrive around Thursday night with ample rain possible behind it through the weekend. A severe cell or two may be possible Friday afternoon and evening.

DISCUSSION

WEATHER PATTERN OVERVIEW: A low pressure system will exit to the north and east this morning. Isolated fog patches will be possible across the Yellowstone Valley where clouds do clear out for radiational cooling. Ensemble data sets suggesting influence from this trough will linger in far northeast Montana today with showers dropping south across the International border. So, there is a decent chance of rain showers and weak thunderstorms occurring in the far northeast from noon into the early evening.

Wednesday into Thursday: High temperatures are expected to reach their peak on Thursday as the ridge moves across the area.

Thursday night into Friday: An upper trough over the PCNW is expected to strengthen late Thursday and send the first shortwave in the flow into the region overnight. THis will bring showers and thunderstorms into the area through Friday and exit by the late afternoon hours.

Friday night onward: The PCNW trough itself digs in deep over Western Montana and Wyoming. This will pull in Gulf Moisture and exiting ridge heat to generate a larger chance for thunderstorms. If the energy arrives earlier in the afternoon and evening Friday a potential severe thunderstorms set up is in the cards. Afterward storms should taper off to a steady rain through the weekend as the PCNW trough moves across the region.

FORECAST CONFIDENCE & DEVIATIONS: Only deviation was to NBM PPI01 which continues to have problems right at the 00-01Z hour with jagged progression in PoP trends.

There is MODERATE confidence on rain showers and weak thunderstorms occurring in the far northeast this afternoon.

There is HIGH confidence in rain showers and thunderstorms occurring this weekend. Confidence is the same in accumulations exceeding half an inch of rain from Thursday night through Monday.

AVIATION

LAST UPDATE: 0400Z

FLIGHT CAT RANGE: VFR

DISCUSSION: Early morning MVFR ceilings will be possible across the terminals from 13-18Z then ceilings should thin out to FEW to SCT. Low level FOG around the Yellowstone contributing creeks and streams also looks to be possible through 18Z this morning. Dry conditions and minimal mid-level clouds are then expected into tonight.

WIND: W at 10 kts or less through the morning hours. Slowly veeering NW and increasing to 10 to 20 kts this afternoon. Then, veering N at 10 kts or less tonight.

GAH

GGW WATCHES/WARNINGS/ADVISORIES

None.