textproduct: Great Falls

KEY MESSAGES

- Warm and dry conditions continue through Friday, with warmest temperatures expected on Monday.

- Elevated fire weather concerns develop with breezy to locally gusty conditions across portions of north-central MT Monday.

- Confidence is increasing for shift towards cooler/wetter weather beginning Saturday and continuing through at least Monday.

DISCUSSION

- Meteorological Overview:

Dry and mild conditions persist across the Northern Rockies and MT through much of the upcoming work week as large scale ridging remains centered across the SW US with the ridge flattening some after Monday. The warmest daytime temperatures are on track for Monday as increased mid-level westerly flow over the flattening ridge provides some additional warming to the lee of the Rockies. This also results in increased surface winds on Monday, particularly across north-central MT where gusts in excess of 30 mph are likely in areas adjacent to the Rockies and central MT mountains. After peaking around 20 degrees above seasonal averages Monday with a few locations potentially approaching daily records, temperatures are likely to remain 10-15 degrees above average through Friday. Hoenisch

Confidence is increasing for a significant change in the current weather pattern beginning Saturday due to the development of an upper level trough and cold air moving into the region. While Saturday is expected to be 10-20 degrees cooler than Friday, there is increasing confidence that this will be followed by another 5-15 degree drop between Saturday and Sunday. Additionally, while there is uncertainty with accumulation amounts, most models are beginning to agree that there is the potential for some form of widespread snowfall Saturday night into the beginning of the following week. Actual accumulations will likely be dependent on the amount of moisture and the timing of the second cool off as the bulk of the precip is currently expected Saturday night through Sunday. ESH

- Forecast Confidence & Scenarios:

The main weather hazard to watch over the coming days will be elevated fire weather concerns developing Monday as anomalously warm afternoon temperatures combine with low afternoon humidity and breezy to locally windy conditions. This is most pronounced across areas areas from the east slopes of the Rocky Mtn Front eastward across areas adjacent to the central MT mountains where wind gusts in excess of 30-35 mph are most likely. While fuels are not currently critical, these conditions will begin a trend toward higher fire danger in the upcoming week. Hoenisch

While there is still uncertainty with the potential widespread snow event next weekend, confidence is increasing for snow accumulations of over 1" for western and central Montana. Models are currently favoring the Rockies and central Montana for the highest totals, although most models do have total snow accumulations remaining under 5". It is worth noting, as we are still many days out from the potential event, we could still see large swings in the model outputs, especially for total snow accumulations. ESH

AVIATION

04/18Z TAF Period.

VFR conditions and light winds will prevail through much of the 0418/0518 TAF period; however, southwest to west winds will begin to increase between 00-06z Monday at the KEKS, KGTF, and KCTB terminals. - Moldan

PRELIMINARY POINT TEMPS/POPS

GTF 53 84 51 78 / 0 0 0 0 CTB 48 76 45 73 / 0 0 0 0 HLN 48 83 47 79 / 0 0 0 0 BZN 46 81 45 77 / 0 0 0 0 WYS 36 76 36 74 / 0 0 0 0 DLN 46 82 46 79 / 0 0 0 0 HVR 45 82 46 75 / 0 0 0 0 LWT 54 83 50 76 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Red Flag Warning for Gallatin National Forest in Gallatin and Madison Counties from Monday afternoon through Monday evening.