textproduct: Great Falls

KEY MESSAGES

- Tonight through Thursday and Friday night through Saturday morning there will be isolated showers and thunderstorms.

- It will be warm through Friday, with a brief cooldown on Saturday.

- Sunday through early next week it will be warm and mostly dry.

DISCUSSION

- Meteorological Overview:

This afternoon there is an upper-level ridge over North-central, Central, and Southwestern Montana. This will allow temperatures to warm up with mostly dry weather. This evening into tonight an upper- level shortwave moves through the upper-level ridge shifting it westward. This combined with northwest flow aloft will bring showers and isolated thunderstorms to portions of North-central and Central Montana this evening through Thursday morning. Any thunderstorm will bring gusty winds and lightning. On Thursday there will be northwest flow aloft over North-central, Central, and Southwestern Montana. This will bring isolated showers and thunderstorms to portions of North-central, Central, and Southwestern Montana.

On Friday an upper-level ridge briefly builds in over North-central, Central, and Southwestern Montana. This will bring warm and mostly dry weather to the area on Friday. Friday evening/night the upper- level ridge moves west combined with an upper-level shortwave moving through the flow. This combined with northwest flow aloft will bring isolated showers and thunderstorms to portions of North-central, Central, and Southwestern Montana Friday evening through Saturday morning. On Saturday northwest flow aloft remains over North-central, Central, and Southwestern Montana. This will bring isolated showers and thunderstorms to the area on Saturday morning and early afternoon with slightly cooler temperatures. Sunday through Tuesday an upper-level ridge builds in over North- central, Central, and Southwestern Montana. This will bring warm and mostly dry weather to the area Sunday through Tuesday. -IG

- Forecast Confidence & Scenarios:

On Thursday there is a 15 - 30% chance for thunder across portions of North-central and Central Montana. On Saturday there is a 15 - 20% chance for thunder across Blaine and Fergus Counties. On Thursday there is a 10 - 40% chance for a quarter inch of rain over portions of North-central and Central Montana. On Saturday there is a 20 - 50% chance for a tenth of an inch of rain or greater.

Sunday through early next week ensembles and deterministic models are in good agreement that there will be upper-level ridging over Montana. This leads to high confidence in Sunday through early next week there being a period of warm and mostly dry weather. -IG

AVIATION

07/00Z TAF Period

Expect increasing clouds with a chance for showers and isolated thunderstorms overnight. For now, I kept thunderstorms out of the terminals, but some lightning might be close. Surface winds increase out of the northwest for most sites. Some scattered showers will continue during the day on Thu, with some minor impacts possible to terminal sites. Mountains/passes will become obscured this evening, and generally be obscured throughout the day on Thursday. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 48 67 43 74 / 60 50 30 0 CTB 45 67 40 73 / 40 30 10 0 HLN 46 68 41 75 / 40 40 10 0 BZN 39 68 37 72 / 40 20 10 0 WYS 33 64 31 68 / 30 20 0 0 DLN 42 70 38 72 / 40 10 0 0 HVR 38 73 39 77 / 10 20 0 0 LWT 41 63 38 70 / 50 70 20 0

TFX WATCHES/WARNINGS/ADVISORIES

None.