Special Weather Statement, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
338 AM MDT Sun Aug 7 2016

...Strong Thunderstorms this Afternoon/Evening...

.DISCUSSION...Satellite is indicating the disturbance that will be
bringing numerous showers and thunderstorms today is exiting
northern Nevada. This feature should begin to cause convection
over north central Idaho later this morning. Then this disturbance
moves into western Montana by late morning/early afternoon and
interact with an unstable atmosphere. Thunderstorms are
anticipated to become fairly strong across western Montana with
the potential of a storm becoming severe. These storms will be
capable of frequent lightning, gusty winds and small hail. Also
this feature will be interacting with a significant plume of
moisture, so moderate to heavy rainfall rates should be expected
with the storms. Models are indicating that the heaviest rainfall
could be over the Glacier National Park area this afternoon and
evening, so a flash flood watch has been issued. The disturbance
moves off to the east tonight allowing convection to steadily
diminish overnight.

Monday into Tuesday, an upper level low will slowly push through
central Washington into the Idaho Panhandle allowing for a decent
chance of showers and thunderstorms across the Northern Rockies.
Precipitation looks to be focused across Southwest Montana Monday
afternoon, shifting into Northwest Montana for Tuesday. By
Wednesday morning, the low is expected to be across far Northwest
Montana with much of the shower activity gradually diminishing.

Throughout the early week period, daytime temperatures will be
5-10 degrees below normal with highs in the 70s for many valley
locations. It will also be breezy on Tuesday. Those with outdoor
plans should prepare for showery conditions with perhaps a strong
thunderstorm or two. In Glacier N.P., late Tuesday into Wednesday
morning will be particularly cool and showery, leading to raw
conditions at the higher elevations.

By late this week, forecast models indicate high pressure ridging which
will allow for significant warming and drying.

&&

.AVIATION...A disturbance will be moving through the Northern
Rockies today causing numerous showers and thunderstorms. The
shower activity will start in north central Idaho this morning
then spread into western Montana this afternoon. A few of these
storms could be quite strong producing gusty erratic winds, small
hail and heavy rainfall. KSMN could be impacted by 07/18z, KBTM &
KMSO by 07/20z and KGPI by 07/22z. The convection will steadily
decrease throughout the evening.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Flash Flood Watch from this afternoon through this evening West
     Glacier Region.

ID...&&

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
1144 AM MDT SUN AUG 7 2016

IDZ009-010-071815-
EASTERN LEMHI COUNTY ID-WESTERN LEMHI COUNTY ID-
1144 AM MDT SUN AUG 7 2016

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN LEMHI COUNTY UNTIL
1215 PM MDT...

AT 1143 AM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 17
MILES WEST OF SALMON...MOVING NORTHEAST AT 40 MPH.

HALF INCH HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
SALMON...LEESBURG...SHOUP AND COBALT.

LAT...LON 4497 11433 4510 11453 4546 11422 4519 11385
TIME...MOT...LOC 1743Z 218DEG 36KT 4514 11425