Severe Thunderstorm Warning 4, NWS Missoula, MT

968 
WWUS55 KMSO 102123
SVSMSO

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
323 PM MDT MON JUN 10 2013

IDC059-102133-
/O.EXP.KMSO.SV.W.0004.000000T0000Z-130610T2130Z/
LEMHI ID-
323 PM MDT MON JUN 10 2013

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN LEMHI COUNTY
EXPIRES AT 330 PM MDT...

LAT...LON 4444 11345 4442 11354 4456 11381 4485 11341
      4480 11333 4483 11325 4479 11314 4463 11304
      4459 11306 4457 11304 4437 11339
TIME...MOT...LOC 2123Z 231DEG 29KT 4475 11315

$$

Area Forecast Discussion
National Weather Service Missoula MT
230 PM MDT Mon Jun 10 2013

.DISCUSSION...High pressure should support dry conditions for
western Montana and north central Idaho this evening and tonight.
The exception is from Salmon to Leadore northeastward to the
Butte area where the atmosphere may be unstable enough to support
a few thunderstorms. The lower levels are quite dry, so any storms
that develop will produce strong gusty winds.

A weak upper level disturbance will brush southwest Montana and
Lemhi County late tonight and may again support a few showers.

As a trough of low pressure develops along the Pacific Northwest
coast Tuesday and Wednesday, the atmosphere will slowly moisten
and become more unstable. The main afternoon shower or
thunderstorm threat Tuesday should be from Lemhi County northward
to the Sapphire Mountains and then eastward across southwest
Montana, including Butte and Anaconda. A few showers may also
develop over Glacier Park late Tuesday. These storms may produce a
variety of weather including gusty winds and very brief heavy rain
showers. By Wednesday, the air mass should further moisten with
the threat of showers and thunderstorms spreading further west
across most of western Montana.

The main trough of low pressure is expected to shift across the
northern Rockies Thursday into Friday. This weather system is
packing quite a bit of moisture so showers are expected in most
areas from Grangeville and Orofino eastward across western
Montana. In addition to the moisture, a quite cool air mass should
lower snow levels to 6000 to 8000 feet by Friday morning with
light snow accumulations possible in the higher terrain from the
Bitterroot Mountains to the Mission Mountains, Swan Range and
Glacier National Park. Temperatures in the valleys should cool to
5 to 10 degrees below normal Thursday and Friday.

In the longer term, it appears high pressure may return over the
weekend and support warmer and drier conditions.

&&

.AVIATION...The northern Rockies are mostly under the influence
of a dry air mass, causing mostly sunny skies with a few clouds
over the mountains at most terminals except KSMN. A moist air mass
from the southwest is encroaching in southern Lemhi County.
Afternoon and evening thunderstorms in this air mass may impact
KSMN. Periods of erratic winds at KSMN are likely due to outflows
from nearby convection. Showers and isolated thunderstorms will
continue well into the evening near KSMN due to a weak disturbance
along the edge of the moist air mass.

&&

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

Follow us on Facebook and Twitter!
https://www.facebook.com/US.NationalWeatherService.Missoula.gov
https://www.twitter.com/NWSMissoula

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
242 PM MDT MON JUN 10 2013

IDZ010-102115-
EASTERN LEMHI COUNTY-
242 PM MDT MON JUN 10 2013

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LEMHI COUNTY UNTIL
315 PM MDT...

AT 236 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 8 MILES SOUTH OF LEADORE...OR 42 MILES EAST OF
CHALLIS.  THIS STORM WAS NEARLY STATIONARY.

WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH
FREQUENT DANGEROUS LIGHTNING.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...LEADORE.

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 4448 11376 4481 11335 4480 11333 4483 11326
      4477 11312 4463 11304 4461 11306 4458 11305
      4442 11344 4444 11346 4442 11350 4442 11356
TIME...MOT...LOC 2042Z 180DEG 0KT 4457 11337