textproduct: Great Falls

KEY MESSAGES

- Persistent smoke, with warm and dry conditions through early next week.

- Some precipitation begins to enter the forecast Wednesday onward, with greatest probability near the International Border.

DISCUSSION

- Meteorological Overview:

Zonal flow aloft will remain in place across the region through early next week. Wildfire smoke originating from OR, WA, and ID will continue to overspread much of the region as a result. Near to a touch above average temperatures are forecast over this timeframe, with largely dry conditions continuing. A few showers or thunderstorms here or there cannot be ruled out, but they look to be very isolated.

Toward the middle of next week ensembles are in favor of a cooler stretch with opportunities for some rain. Areas near the International Border will be most favored, while areas near the ID border look less favored. -AM

- Forecast Confidence & Scenarios:

Rain and temperatures next week:

Wednesday and Thursday the probability for a quarter of an inch of rain is greater than 50% across the Hi-Line, slowly decreasing as you head further south toward Southwest Montana. By Thursday the probability for a high temperature of less than 70 F is 50% or greater over much of the plains. Southwest valleys look to be a little bit warmer, hence the probability for a 70 F or lower high temperature on Thursday is 30% or less. -AM

AVIATION

08/18Z TAF Period

VFR conditions will prevail across all terminals during this TAF Period outside of the KBZN and KEKS terminals. Through at least 09/06Z smoke from wildfires will reduce visibility to MVFR levels and periodically to IFR-levels at the KEKS and KBZN terminals. At all of the TAF sites during this TAF Period there will be multiple wind shifts. Across most of the TAF sites smoke from wildfires will reduce slantwise visibility during the majority of this TAF Period. During the majority of this TAF Period there will be mountain obscuration across Southwestern Montana due to smoke. -IG

KGTF: For the most part today winds will stay below 15 kts. The main concern will be shifting winds. Winds shift to the north around 21Z, shift to more northeasterly around 00Z, and shift to more easterly by 03Z. The probability for exceeding a 15 kt crosswind is 30% between 18Z and 03Z. -IG

FIRE WEATHER

A Red Flag Warning remains in effect for the southern districts through today. The combination of gusty afternoon winds, low humidity and hot temperatures will create critical fire weather conditons. Because of all the smoke, some locations might not mix the winds aloft today, resulting in the potential for the Red Flag Warning to be cancelled early. Expect some wind shifts over North Central MT today and Sunday, with cooler temperatures/wetter conditions over North Central as well by the middle of next week. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 56 86 55 89 / 0 0 0 0 CTB 50 80 50 82 / 0 0 0 0 HLN 57 88 55 88 / 0 0 0 0 BZN 53 87 52 91 / 0 0 0 0 WYS 44 85 44 87 / 20 0 0 0 DLN 52 85 52 89 / 0 0 0 0 HVR 55 86 53 88 / 0 0 0 0 LWT 55 83 52 86 / 0 0 0 10

TFX WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 9 PM MDT this evening for Central and Eastern Lewis and Clark National Forest Areas-Helena and Townsend Ranger Districts of the Helena National Forest-Lincoln Ranger District of the Helena National Forest.