Special Weather Statement, NWS Missoula, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
232 PM MDT MON AUG 8 2011

.DISCUSSION...THE ATMOSPHERE HAS BECOME UNSTABLE ACROSS THE
REGION. HOWEVER...ANY SHOWERS OR STORMS THAT DEVELOP WILL BE
ASSOCIATED WITH TWO DISTINCT MOISTURE FEEDS.  FIRST...MOISTURE
MOVING ACROSS NORTHWEST MONTANA WILL SUPPORT A FEW SHOWERS AND
ISOLATED THUNDERSTORMS FROM ABOUT EUREKA TO KALISPELL AND EASTWARD
AS WELL AS THE MISSION AND SWAN MOUNTAINS. A SECOND FEED OF
MOISTURE FROM NORTH CENTRAL OREGON ACROSS THE SOUTHERN
CLEARWATERS...EXTREME SOUTHERN BITTERROOTS...LEMHI COUNTY AND
PINTLAR TO BUTTE REGION WILL SUPPORT ISOLATED THUNDERSTORMS. THIS
MORE SOUTHERN FEED OF MOISTURE SHOULD PERSIST THROUGH THE NIGHT.

OVERALL...THE WEATHER PATTERN DOES NOT CHANGE MUCH TUESDAY WITH
SOME MOISTURE LINGERING NEAR THE CANADIAN BORDER AND ALSO
SOUTHWEST MONTANA AND LEMHI COUNTY.

A MORE ORGANIZED WEATHER SYSTEM IS EXPECTED TO BRUSH THE REGION
WEDNESDAY AFTERNOON AND EVENING. THE MAIN IMPACT SHOULD BE TO
INCREASE THE AFTERNOON AND EVENING WINDS AND PRODUCE CHOPPY LAKE
CONDITIONS...ESPECIALLY ACROSS FLATHEAD LAKE. HOWEVER...THE
THREAT OF SHOWERS AND THUNDERSTORMS MAY INCREASE SLIGHTLY FROM
NEAR THE BITTERROOTS TO THE SOUTH AND EASTWARD.

A DRIER WESTERLY FLOW IS EXPECTED THURSDAY INTO FRIDAY WITH COOLER
NIGHTS.

LONGER RANGE GUIDANCE CONTINUES TO SUGGEST A RIDGE OF HIGH
PRESSURE AND HOT AIR MASS MAY BECOME ESTABLISHED OVER THE NORTHERN
ROCKIES SATURDAY AND SUNDAY.

&&

.AVIATION...THE ATMOSPHERE CONTINUES TO BECOME FAIRLY UNSTABLE AND
INTERACT WITH TWO PLUMES OF MOISTURE. ONE PLUME ALONG THE CANADIAN
BORDER SHOULD CAUSE SCATTERED SHOWERS AND AN ISOLATED THUNDERSTORM
THIS EVENING. KGPI HAS THE POTENTIAL OF SEEING AN ISOLATED
SHOWER/THUNDERSTORM AFTER 08/22Z. THE SECOND MOISTURE FIELD IS
DRAPED OVER CENTRAL IDAHO MOVING TOWARDS SOUTHWEST MONTANA. KBTM
AND KSMN COULD ENCOUNTER SOME CONVECTION THIS AFTERNOON AND
EVENING. THESE SHOWERS HAVE THE POTENTIAL TO LINGER THROUGHOUT
THE NIGHT ACROSS LEMHI COUNTY AND SOUTHWEST MONTANA.

&&

NOTE: FLOOD WATCHES...WARNINGS AND ADVISORIES WILL NOT BE LISTED BELOW.

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

SHORT TERM...BAUCK
LONG TERM....BAUCK
AVIATION...SMITH

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
852 PM MDT MON AUG 8 2011

MTZ001>003-090345-
FLATHEAD/MISSION VALLEYS-KOOTENAI/CABINET REGION-WEST GLACIER/BOB
MARSHALL REGION-
852 PM MDT MON AUG 8 2011

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN FLATHEAD AND
NORTHWESTERN LAKE COUNTIES UNTIL 945 PM MDT...

AT 840 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 11 MILES NORTHWEST OF BIG ARM...OR 20 MILES
NORTHWEST OF POLSON...MOVING EAST AT 15 MPH.

WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH
FREQUENT DANGEROUS LIGHTNING. WIND GUSTS MAY BRIEFLY INCREASE WAVE
HEIGHTS ON FLATHEAD LAKE.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...BIG ARM...WOODS
BAY...LAKE MARY RONAN...ELMO...PROCTOR...DAYTON AND ROLLINS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF THREATENING WEATHER APPROACHES YOUR AREA...GO INDOORS AND STAY
AWAY FROM WINDOWS. IF YOU ARE CAUGHT OUTSIDE...MOVE TO A WELL
PROTECTED AREA.

&&

LAT...LON 4805 11397 4779 11391 4778 11454 4796 11457
TIME...MOT...LOC 0250Z 261DEG 13KT 4787 11446