textproduct: Great Falls

KEY MESSAGES

- Precipitation diminishes this evening but impacts from recent locally excessive rainfall may linger in the Glacier National Park area.

- Drier weather develops with a return to more seasonable temperatures for the remainder of the week and upcoming weekend.

- A few showers and and thunderstorms may develop each afternoon through Friday.

DISCUSSION

The closed upper level low centered over central MT continues to circulate moisture and areas of precipitation across the region this afternoon with precipitation diminishing this evening as the upper level low slowly lifts out to the northeast. A few isolated thunderstorms are possible through early this evening, mainly near the Canadian border. While lingering precipitation is generally light, a few heavier showers remain possible in association with weak thunderstorm activity near the Canadian border, including portions of Glacier NP.

A drier pattern develops Tuesday through the rest of the week though some troughing in the larger scale flow lingers across the NW US and Northern Rockies through Friday. Weak disturbances and residual moisture will likely combine with daytime instability for isolated to widely scattered showers and a few thunderstorms each afternoon. Loosely organized shortwaves moving through the flow Wednesday and again Friday could facilitate a greater coverage of showers and thunderstorms those days with the Friday wave potentially bringing enough shear and CAPE to support a few stronger storms. Otherwise, temperatures warm back to near seasonal averages through the rest of the week. Longer range model ensembles generally support ridging this weekend for overall dry conditions with some additional warming. Hoenisch

AVIATION

29/18Z TAF Period

Mainly stratiform type precipitation continues across the region through this afternoon and evening. Showery activity looks to be reserved for northern areas, where weak instability looks to develop this afternoon. Ceilings and visibility gradually improves beginning tonight into Tuesday. Mountains will remain obscured through most of the TAF period. -AM

HYDROLOGY

A Flood Warning has been issued for the Many Glacier area where recent excessive rainfall has led to several trail closures and rises on Swiftcurrent creek are impacting road access with forecasts indicating additional rises on the creek through early this evening. A Flood Watch continues for the rest of Glacier Park and adjacent areas where 2-5 inches of precipitation has fallen over the last 48hrs and up to 0.50" of precipitation is possible in additional showers through early this evening. Most creeks originating from the Glacier NP and the Northern Rocky Mtn front have shown moderate rises from the runoff and will continue to be monitored. Hoenisch

PRELIMINARY POINT TEMPS/POPS

GTF 48 73 50 74 / 90 20 10 30 CTB 48 70 48 71 / 90 30 0 0 HLN 48 72 51 72 / 80 40 50 80 BZN 43 70 44 72 / 70 30 40 60 WYS 33 61 33 67 / 70 30 20 20 DLN 40 67 43 71 / 50 50 70 50 HVR 48 75 50 78 / 70 40 10 10 LWT 44 70 45 72 / 90 30 10 60

TFX WATCHES/WARNINGS/ADVISORIES

Flood Watch until midnight MDT tonight for East Glacier Park Region.