textproduct: Great Falls

KEY MESSAGES

- Warmer and dry conditions today after a cool start this morning.

- Showers and a few thunderstorms track across the area tonight with a lingering chance of showers through Thursday afternoon.

- Temperatures fluctuate near to above seasonal averages through the weekend with another chance for showers and thunderstorms Friday night through Saturday.

DISCUSSION

/Issued 507 AM MDT Wed May 6 2026/

- Meteorological Overview:

An upper level ridge with axis north along the BC/AB border this morning slumps southward across the Northern Rockies today, providing dry and seasonably warm conditions (after a cool morning start) through this afternoon. A shortwave disturbance from the Pacific moves over the de-amplifying upper ridge and slides southeast into the Northern Rockies tonight with showers and isolated thunderstorms developing initially across NW MT and along the continental divide this evening, before tracking east across primarily north-central and central MT later this evening and overnight. Showers continue across these areas into Thursday morning with lingering moisture and additional disturbances maintaining at least an isolated to widely scattered coverage of showers through Thursday afternoon.

Ridging briefly rebuilds across the area on Friday for mainly dry and warmer conditions before another shortwave disturbance slides across the region Friday night through Saturday. Showers and a few thunderstorms are possible with this feature, primarily across north- central MT, where there is still considerable spread among model ensembles with specific amounts. Temperatures also cool some on Saturday but remain within a few degrees of seasonal averages.

Longer range model ensembles continue to favor upper level ridging centered inland of the west coast on Sunday with overall ridging persisting through early next week. This would provide warm and dry conditions on Sunday and likely into into the the first part of next week, though confidence in the amplitude of ridging decreases with time. Hoenisch

- Forecast Confidence & Scenarios:

While the timing of the shortwave disturbance tonight/Thursday morning is not favorable for widespread or strong thunderstorm development, there is a moderate influx of Pacific moisture (PWAT's .50-.70")and enough mid-level instability along with some upper level jet support to sustain thunderstorm activity across central MT late this evening through the overnight period. Locally gusty winds (30-40mph) and isolated lightning would be the main impact with this activity, with a 20-40% chance of occurrence for areas near Great Falls, Helena and Lewistown between midnight and 5am Thursday. Hoenisch

AVIATION

06/18Z TAF Period

VFR conditions prevail through the remainder of the day across the region under mainly clear skies. Westerly to northwesterly winds develop this afternoon at many terminals, subsiding around sunset. A round of showers and perhaps a few thunderstorms will move from northwest to southeast across the region, initially across far SW MT this afternoon, but across the remainder of the region this evening into tonight, bringing brief instances of MVFR conditions and gusty winds. A wind shift to a more northwesterly direction moves over the plains late tonight and early in the day Thursday. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 72 49 67 44 / 0 40 50 10 CTB 72 46 67 40 / 0 20 30 10 HLN 71 47 69 42 / 0 20 30 10 BZN 67 39 69 38 / 0 20 20 0 WYS 60 33 64 31 / 0 10 30 0 DLN 68 42 71 38 / 0 10 0 0 HVR 68 38 72 39 / 0 10 20 0 LWT 62 41 63 39 / 0 30 60 10

TFX WATCHES/WARNINGS/ADVISORIES

None.