textproduct: Great Falls

KEY MESSAGES

- Isolated shower or a thunderstorm through Sunday.

- Very warm temperatures arrive Sunday and continue through Tuesday.

- Showers and thunderstorms will be more widespread Monday evening through Thursday, with some storms being strong or producing heavy rainfall.

DISCUSSION

- Meteorological Overview: Some cold air continues to linger aloft from the recent upper level low that moved through the area this week. This is resulting in a few isolated showers/thunderstorms, mostly over North Central MT. This precipitation will diminish rather quickly after sunset.

Expect a repeat of these conditons on Saturday and Sunday, but the overall coverage from any storms will be on the decrease, with Sunday having the lowest chances for any storms. Temperatures will continue to warm over the weekend, with afternoon highs in the mid 80s for many areas by Sunday.

For Memorial Day, an upper level low will start to approach Western MT by late in the day. This will result in an unstable southwesterly flow aloft over Central MT. With the airmass becoming unstable by the evening hours, showers/thunderstorms will be possible by Monday evening over much of Central and North Central MT. It is possible that a few of these storms could be on the stronger side.

For Tuesday through next Friday...The upper level level tries to slowly move eastward over MT, but gradually fades out/weakens as it moves over Central MT. It will take several days for this upper level to move from Western MT into Central MT. Thus, daily chances for showers/thunderstorms is expected over the CWA from Tue through Fri, with the potential that a few storms could be strong, especially on Tue. Additionally, the airmass will continue to moisten through the week, and the potential will increase for some storms to produce heavy rainfall at times. Generally above normal temperatures are expected for late next week. Note, not all areas will receive rainfall each day next week.

- Forecast Confidence & Scenarios: Overall, there is less than a 20 percent for showers/thunderstorms today through Sunday. The probability for stronger storms or storms that will produce heavy rainfall will start to increase Mon, and especially on Tue.

AVIATION

22/18Z TAF Period

VFR conditions will prevail across all terminals during this TAF Period. Scattered light showers are expected across the area, but probabilities were only about 5-10% across the terminals, so they were not included in the TAFs. Winds will be light and westerly when not variable. - Dzomba

PRELIMINARY POINT TEMPS/POPS

GTF 41 75 46 82 / 10 0 0 0 CTB 37 73 43 78 / 30 10 0 0 HLN 41 75 44 82 / 0 0 0 0 BZN 36 73 41 81 / 0 0 0 0 WYS 29 68 34 74 / 20 0 0 10 DLN 37 73 41 80 / 10 0 0 0 HVR 40 78 47 86 / 0 0 0 0 LWT 38 70 43 80 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

None.