textproduct: Glasgow

KEY MESSAGES

- The next chance for isolated showers and perhaps a lone thunderstorm is across the northeast this afternoon. Brief downburst winds may be possible with any passage.

- Above normal temps, low relative humidity, strong nw winds with potential for shower enhanced downbursts, and pre-greenup fuels has lead to a Red Flag Warning across the east today.

- A weak disturbance arrives tonight into Saturday with up to a tenth of an inch possible over Petroleum, SW Phillips, and SW Garfield counties.

- Above normal temps with mainly dry conditions are expected to return Sunday and run through the work week.

DISCUSSION

WEATHER PATTERN OVERVIEW: Currently a low pressure system lies over the Hudson Bay while a ridge runs up the western North American coast from southern California to British Columbia. Northeast Montana is in between these two features under northwest flow aloft.

A weak shortwave will work its way through the flow pattern and drag some afternoon showers and an isolated thunderstorm or two through the northeastern zones this afternoon and evening. The pressure gradient force will strengthen up just prior to a cold front moving through the same area this evening. This will allow for moderate to strong NW winds initially. However, the showers moving through could easily get accelerated by low relative humidity and provide downburst winds that fan flames for the Red Flag Warning regions. Looking at GOES NDVI most areas across the east are around or below 20-30% greenness had already justified the Red Flag Warning that was in effect for fire weather zones 120 and 122 from noon Friday through 8 PM Friday. So, throwing the chance for downburst winds into the mix now makes things especially dangerous.

Saturday: With the cold front moving through the previous night a zone of lift will be associated with the post frontal disturbance across central Montana for about 24 hours. This will have some impact across the southwest including Petroleum, SW Phillips, and SW Garfield counties. Precipitation accumulation ranges from a few hundredths up to around a tenth of an inch is possible in the southwest.

Sunday through the work week: Ridge to the west moves across the region, flatten, and then rebounds in the west by Wednesday. The latest GFS ensemble suggests backbuilding of a trough over North Dakota on Monday into Tuesday, but there is high uncertainty on whether or not substantial precipitation chances will reach northeast Montana at that time.

FORECAST CONFIDENCE & DEVIATIONS: Deviations from NBM were focused on PoPs. Current NBM PPI01 had nothing across the northeast for precip in GFE. Radar echos showed the beginning of rain showers forming just across the Canadian border and almost every individual CAM in GFE had something. So, used the broad bulk of CAMs NPoPs to blend in some semblance of rain showers for the northeast. Surprisingly, earlier GFE HREF (12 hours old) also did not have anything in this location, with hi- res CAMs only catching on in the last 6 to 9 hours. Latest SPC HREF does indicate that these rain showers could have downburst winds mixed in.

There is HIGH confidence in rain showers occuring in the northeast part of the area occurring this afternoon. There is MODERATE confidence in showers occurring in the southwest this evening. There is LOW confidence in thunderstorms at either region.

There is HIGH confidence of critical fire weather conditions occurring on this afternoon for fire weather zones 120 and 122.

There is HIGH confidence in rain showers across Petroleum, SW Phillips, and SW Garfield counties Friday night into Saturday, with LOW confidence on these locations receiving a tenth of an inch of precipitation.

AVIATION

LAST UPDATED: 1900Z

FLIGHT CAT RANGE: VFR

DISCUSSION: A small chance (5 to 20%) for showers or an isolated thunderstorm move a through the TAFs between 18 and 03Z. Any shower that moves through could produce a rogue downburst wind across the region. This chance will be too low to include in the TAFs directly though. Afterward conditions go back to dry at the terminals through Saturday.

WIND: NW at 5 to 15 gust 25 kts today. Slowly veering NE behind a front and reducing to 5 to 10 kts in the late evening hours through the Saturday morning. Backing to N at 10 to 15 kts Saturday afternoon.

GAH

GGW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 8 PM MDT this evening for Dawson/McCone/Prairie/Richland/Wibaux Counties-Fort Peck Reservation and Daniels/Roosevelt/Sheridan Counties.