textproduct: Glasgow

KEY MESSAGES

- Seasonably warm temperatures are expected for Monday and Tuesday, along with an isolated to widely scattered afternoon and evening thunderstorm potential.

- A potential major pattern shift will occur around midweek. This change will bring much cooler temperatures and very beneficial rain. Some locations could possibly get north of an inch of rain over a 2 day span.

DISCUSSION

WEATHER PATTERN OVERVIEW:

The rest of today through Tuesday will feature seasonably warm temperatures across NE Montana accompanied by isolated to widely scattered afternoon and evening thunderstorms while ridging remains pronounced across the Northern High Plains. Chances for any specific location to receive any showers or storms through tomorrow is relatively low (<20%) but cannot be completely ruled out.

Toward the middle of the week a potentially significant pattern shift is expected to take place for northeast Montana. This shift will lead to increasing daily chances for showers and thunderstorms, with heavy rain potential as some southwestern monsoonal moisture does transport its way this far north. There will also be a major cooling with this pattern, where highs will be in the 60s and 70s for many places as opposed to the current 80s to 90s.

FORECAST CONFIDENCE & DEVIATIONS:

Did not deviate from base forecast today. Confidence in any precipitation amounts are still relatively low at this point, especially given the significant jump in accumulation from previous forecast iterations, but this could set up to be a low- confidence/high- impact scenario where many locations could get north of 1" of total rainfall this week. Beyond the rain, confidence is moderate in the big temperature swing associated with the major pattern shift that could bring the aforementioned rain. Once the system moves off to the east, confidence goes down with respect to whether or not the region returns to warm and dry, or if chances for rain will persist into the weekend and next week.

Cliff

AVIATION

LAST UPDATE: Monday August 10 at 1900Z.

FLIGHT CAT RANGE: VFR.

DISCUSSION: Haze from wildfire smoke and a few high level clouds will continue to drift over northeast Montana through Tuesday. Expect mostly dry conditions, though a stray isolated shower or quick thunderstorm cannot be ruled out, however chances for any specific location or airfield will be low.

WIND: Look for steady and persistent east winds, ranging from 5 to 15 kts, occasionally with stronger gusts through Tuesday morning, when winds should shift to the north-northwest but remain in the 5-15 kts range.

Cliff

GGW WATCHES/WARNINGS/ADVISORIES

None.