textproduct: Glasgow

KEY MESSAGES

- Thunderstorms are possible this evening with an isolated severe hail and wind threat.

- The next frontal system will approach the area with more widespread thunderstorms late Monday night and continue through Tuesday. Isolated severe storms are possible but heavy rainfall is an increasing concern.

- Unsettled weather will likely continue through at least the midweek.

DISCUSSION

WEATHER PATTERN OVERVIEW:

A cold front dropping south into the region this afternoon will be accompanied by a few thunderstorms later this evening. HREF ensemble max wind gust and updraft helicity shows support for an isolated severe storm, especially into the southwest zones tracking in from Central MT. Inverted V soundings, dry mid and low levels, and high DCAPE support a wind threat, even for thunderstorms that may form in northern zones.

A very aggressive shortwave will approach on southwest flow aloft Monday night into Tuesday. This will provide dynamic forcing for ascent in a very moisture rich environment. Widespread thunderstorms are expected to unfold with forecast soundings showing precipitable water values exceeding an inch across the area. Beginning late Monday night/early Tuesday morning, PWAT values maintain above 90th percentile to greatly surpassing maximum values until the late evening Tuesday. Given the flash flooding that has occurred in June/earlier this week across area, the ground is already nearly saturated. Thus, this period will need to be monitored for not only an isolated severe risk, but the potential impacts compounding from additional heavy rainfall.

Ensembles show a continuing progressive weather pattern unfolding with a shortwave ridge Tuesday night into Wednesday followed by the next weather system arriving for Wednesday night. All told, expect thunderstorm chances to continue at times through at least the middle part of the upcoming week.

FORECAST CONFIDENCE & DEVIATIONS:

Increased PoPs to further match with neighbors and increased confidence in heavy rainfall with storms Monday night through Tuesday. Opted to not yet issue a Lake Wind Advisory for tomorrow morning, but if winds increase 2-3 kts, threshold will be met.

AVIATION

LAST UPDATED: 1840Z

FLIGHT CATEGORY: VFR

DISCUSSION: Mostly clear skies with a passing high to mid cloud from time to time. Chances for brief thunderstorms late this evening.

WIND: Light north winds through 10Z tonight, slowly veering east and increasing to 10 - 15 kts.

GGW WATCHES/WARNINGS/ADVISORIES

None.