textproduct: Glasgow

KEY MESSAGES

- Temperatures remain warm through this afternoon before cooler than average temperatures move into the region Saturday and Sunday, trending cooler into the low to mid 60s. Beyond this weekend, warmer temperatures are expected to return early next week.

- Chances of widespread showers return this weekend with the heaviest totals in excess of 1.00" located south of Highway 200 from Winnett to Glendive as well as south of I-94 through Wibaux. Embedded thunderstorms are possible and can cause local heavy rainfall. - Confidence in rainfall totals remain below average in NE Montana due to southerly storm track trends and a sharp precipitation cutoff.

DISCUSSION

SYNOPTIC SETUP:

A low pressure system over northern California will track east into northern Wyoming into the weekend. This system is cutoff by a northern stream shallow ridge in Canada which is leading to dry air cutting off the northern extent of the precipitation for Canadian border regions. Latest NBM forecast QPF shows a much sharper gradient over NE Montana as a result with near little precipitation near the Canadian border. The heaviest totals in excess of 1.00" are likely south of Highway 200 from Winnett to Glendive as well as south of I-94 through Wibaux. Across these southern locations, heavier bands of showers and embedded thunderstorms that remain persistent enough may produce minor flooding of small streams, open fields, and poor drainage locations such as low lying areas.

At this time, confidence in exact precipitation totals through Sunday for NE Montana remains below average given the sharp cutoff to the north, southward trend, and dynamic nature of this system. Thus, will hold off on any flood watches for now. Confidence is greater to the south of the CWA closer to the storm track. The WPC maintains Marginal/Slight Risks for Excessive Rainfall Outlook products over much of Montana for Day 1 and 2. Those traveling across the state should monitor the latest forecast as well as watch and warning products issued by respective weather service offices.

The storm system looks to exit Sunday into Monday with ensembles showing the northern stream ridge having a bit more influence over conditions. As a result look for a warm up in temperatures and drier weather into early next week.

FORECAST CONFIDENCE & DEVIATIONS:

Models continue to show poor run to run continuity in precipitation amounts for NE Montana this weekend, with the gradient tightening across the area and a southward shift. Thus, confidence remains below average for rainfall totals, but increases for southern tier zones closer to the storm track. Areas south of Highway 200 from Wibaux to Glendive and south of I-94 through Wibaux may experience heavier rainfall totals and the potential for minor flooding.

AVIATION

LAST UPDATED: 1845Z

FLIGHT CAT RANGE: VFR trending toward MVFR/IFR.

DISCUSSION:

Showers and isolated thunder look to increase in coverage tonight and Saturday, leading to associated reductions in ceilings and visibility. The highest confidence in persistent heavy rain showers will be across KGDV and KSDY and these terminals are closer to the storm track over northern Wyoming.

SFC Wind: N to NE at 5 to 15 kts through this evening, becoming east on Saturday after 18Z ranging from 10 to 20 kts.

GGW WATCHES/WARNINGS/ADVISORIES

None.