textproduct: Great Falls

KEY MESSAGES

- Scattered showers and thunderstorms across the region this afternoon with isolated severe wind gusts possible.

- Breezy winds and warm temperatures will lead to elevated fire weather conditions through Friday.

- Cooler temperatures, gusty winds, and precipitation continue this weekend into the beginning of next week.

DISCUSSION

- Meteorological Overview:

Strong southwesterly flow ahead of an approaching upper-level trough will bring ample moisture and forcing into the region allowing for scattered to widespread afternoon showers and thunderstorms on Thursday and Friday. A few may become severe with the main concern being strong wind gusts. Additionally, lightning will be a concern as these thunderstorms are expected to be a mix of wet and dry with the dry thunderstorms posing the highest risk for new fire starts.

Towards the weekend the trough starts to move eastward and turns into a cutoff low which will bring cooler temperatures and a chance for widespread precipitation to the region through Sunday. By the beginning of next week some weak transient ridging tries to build over the intermountain west but it does not last long as another Pacific trough starts to make its way towards Montana by the middle of next week bringing yet another chance for more unsettled weather. -thor

AVIATION

27/06Z TAF Period

The current shower and thunderstorm activity will slowly diminish and as it moves off to the east. Southwesterly flow becomes more established over the Northern Rockies on Thursday and brings increased southerly breezes and at least a couple waves of scattered showers and thunderstorms through southwest and north- central MT. The initial round of more isolated and weaker showers and storms will move through roughly between 27/15 and 27/20Z. This will be followed by more widespread clusters of showers and storms between 27/20 and 28/04Z. These storms will be capable of localized strong wind gusts, brief heavy downpours, and cloud to ground lightning. Primarily VFR conditions will prevail, except for the brief MVFR/IFR beneath the stronger convective cores.

For KGTF : Primary concern will be widely scattered showers and thunderstorms again for Thursday, mostly between 27/20 and 28/03Z. Localized strong, erratic wind gusts, brief heavy downpours, and cloud to ground lightning will be the primary hazards. Even without a direct terminal impact, nearby thunderstorms could produce outflow boundaries that result in crosswinds exceeding 15 kts. Away from thunderstorms, winds become southerly on Thursday and will gust to around 20 kts at times. There is around a 50% chance of crosswinds over 15 kts. - RCG

FIRE WEATHER

Very warm, dry, and breezy conditions will combine with thunderstorm activity for elevated fire weather conditions for the next couple of days, especially for southwest and portions of central Montana. The primary concern will be passing waves of showers and thunderstorms, some with little rainfall and cloud to ground lightning. The strongest storms may produce erratic gusty winds over 50 mph,which may help spread new fires. Today and Friday look to be the breeziest and driest days for central and southwestern locations north of I90, with up to a 20% chance for the Hot Dry Windy Index to exceed the 90th percentile. Fire weather products are not planned to be sent out at this time given the marginal conditions, but the situation will continue to be monitored. A Pacific trough brings additional showers and thunderstorms and periods of gusty winds this weekend; however, cooler temperatures and more productive storms looks to reduce the fire risk. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 91 59 94 57 / 0 20 30 30 CTB 87 54 88 54 / 0 20 20 10 HLN 91 55 90 54 / 40 40 40 30 BZN 90 54 89 53 / 20 20 30 30 WYS 85 42 82 43 / 20 20 20 40 DLN 87 52 86 52 / 20 20 40 20 HVR 95 61 98 60 / 0 10 10 30 LWT 93 57 93 56 / 20 20 30 30

TFX WATCHES/WARNINGS/ADVISORIES

None.