Special Weather Statement, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
220 PM MDT Fri Aug 2 2013

.DISCUSSION...
Tonight and Saturday...A very slow moving upper level low system
will continue to circulate moisture into northwest Montana from
southern Alberta and eastern Montana. Occasional light rainfall is
expected in these northern zones with continued cloudy, cool, more
stable conditions. On the other hand, the atmosphere will be
somewhat drier, but more unstable across north-central Idaho and
west-central Montana which falls under a more westerly flow aloft.
The farther south you go, the drier the atmosphere becomes and
therefore the southeast tip of Lemhi county will remain virtually
dry. Temperatures will show a warming trend as moisture decreases
overall and we see more sun breaks during the afternoon.

Sunday...A ridge of high pressure will be building back into the
Northern Rockies region. A warming and drying trend is back in the
forecast with high temperatures returning to the 80s. Any chance
of precipitation will be confined to near the Canadian border.

A weak upper ridge will be a pretty persistent feature over the
Northern Rockies through the coming work week. A deep upper low
over central Canada will keep the ridge from strengthening, and
even direct an occasional short wave disturbance south along the
divide. so this is where a continued mention of some
shower/thunderstorm activity will be placed. And by midweek,
models suggest an increase in subtropical moisture moving up
through the ridge, thus providing a threat of thunderstorms across
the entire region. Temperatures will be seasonable, or generally
in the 80s in the valleys during the day.

&&

.AVIATION...The band of steady precipitation will continue to
linger around northwest Montana, so KGPI should see fairly
consistent rain through tonight. Expect a decreasing trend in
showers starting around 00Z Saturday. Ceilings and visibilities
will be reduced throughout much of the day, then improving later
this evening. KMSO will continue to see the occasional
shower/mountain obscuration, and even a possible thunderstorm or
two through the evening. KBTM and KSMN could see an isolated
shower or thunderstorm through this evening as the atmosphere
destabilizes.

&&

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

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
902 PM MDT FRI AUG 2 2013

IDZ007-008-030345-
LOWER HELLS CANYON/SALMON RIVER REGION-OROFINO/GRANGEVILLE REGION-
802 PM PDT FRI AUG 2 2013

...SIGNIFICANT WEATHER ADVISORY FOR WESTERN IDAHO COUNTY UNTIL 845 PM
PDT...

AT 754 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 13 MILES NORTHWEST OF WHITE BIRD...OR 20 MILES
WEST OF GRANGEVILLE...MOVING NORTHEAST AT 10 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...KEUTERVILLE...
COTTONWOOD AND FENN.

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 4602 11656 4601 11654 4607 11653 4617 11645
      4603 11616 4576 11647 4586 11669
TIME...MOT...LOC 0302Z 214DEG 11KT 4589 11651