textproduct: Great Falls

KEY MESSAGES

- Showers and isolated thunderstorms continue today.

- Temperatures warm through the work week, with a slight cool down on Sunday.

- Another round of showers and thunderstorms for Saturday and Sunday.

DISCUSSION

- Meteorological Overview:

Continued southwest flow from an incoming trough will continue to advect moisture into the state, bringing overnight isolated to widespread showers/isolated thunderstorms. Along the Milk River Valley, there is a low chance for localized patchy fog to develop Thursday morning, but the increasing cloud cover will limit fog development. The main shortwave trough will pass through during the morning to afternoon hours Thursday. Weak instability building in Thursday afternoon will allow for some thunderstorms to develop. Weak shear and mesoscale dynamics will keep thunderstorms on the weaker side. However, a few strong wind gusts can't be ruled out.

After this trough exits, drier conditons are expected for Friday, but with the moist environment, a shower or two can't be ruled out. Heading into the weekend, another trough will begin to push east across the Northwest U.S. On Saturday, southwest flow will advect in warm and unstable air in. This will bring the potential for showers and thunderstorms, with a few strong thunderstorms possible towards Central MT. Increasing winds aloft Saturday across Southwest MT will bring gusty winds. The main wave trough will come through through the day Sunday, which will develop another round of showers and thunderstorms. A cold front passage Sunday will help cool down temperatures to below normal Sunday.

Heading into next week, another trough looks to develop along the west coast, which will keep southwest flow developing showers and thunderstorms. There remains some uncertainty in how this next trough evolves, but active weather with near to slightly above normal temperatures persist next week.

- Forecast Confidence & Scenarios:

Thunderstorms Today:

Weak instability and shear look to keep the thunderstorms weaker. Also, the trough passing through earlier in the day is also a limiting factor. Morning cloud cover can also aid in prohibiting robust surface heating for thunderstorms development. Hi-res guidance still suggests there could be a few storms that produce a 40-50 mph wind gusts, but better chances for severe weather look to stay in the eastern part of the state.

Thunderstorms Saturday:

Saturday looks to have better shear with better winds aloft moving in. However, weaker instability seems to be a limiting factor with thunderstorms. This is likely due to a frontal passage in the morning limiting the buoyancy. Better chances look to be towards eastern MT, but can't rule out a few stronger storms towards Central MT. With winds increasing aloft across Southwest MT, some storms can help mix down some stronger wind gusts. There's a 20 to 60% chance for synoptic wind gusts of 50 mph near the MT/ID border. -Wilson

AVIATION

04/12Z TAF Period.

Showers/thunderstorms will move from west to east across the CWA through afternoon hours. Overall, most of the storms will exit the eastern portions of the CWA by this evening. Breezy conditions develop behind the showers this afternoon over North Central MT. Otherwise, expect clearing skies this evening across the CWA. Mountains/passes could be obscured at times by showers until mid afternoon. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 73 44 78 48 / 50 0 0 0 CTB 69 42 71 44 / 20 0 0 0 HLN 73 44 79 48 / 30 0 0 0 BZN 72 41 81 46 / 40 0 0 0 WYS 70 35 74 39 / 20 0 0 0 DLN 74 42 81 46 / 20 0 0 0 HVR 74 45 79 47 / 50 10 0 10 LWT 68 42 77 45 / 70 0 0 10

TFX WATCHES/WARNINGS/ADVISORIES

None.