Alert Administrative Message
Issued by NWS Missoula, MT

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NOUS75 KMSO 182021
ADMMSO

ADMINISTRATIVE MESSAGE
NATIONAL WEATHER SERVICE MISSOULA MT
1232 PM MDT FRI APR 18 2014

TO ALL WFOS SURROUNDING WFO MSO
FM WFO MSO

WFO MSO HAS ISSUED A HEADS-UP EMAIL TO OUR EMERGENCY MANAGEMENT
COMMUNITY AND OTHER PARTNERS.

EMAIL TOPIC...SIGNIFICANT SPRING STORM NEXT WEEK

...REASONING IN EMAIL...
GREETINGS,

WE ARE SENDING YOU THIS EMAIL DUE TO THE POTENTIAL FOR
A SIGNIFICANT SPRING STORM TO IMPACT MOST OF CENTRAL IDAHO AND
WESTERN MONTANA TUESDAY AFTERNOON/EVENING INTO THURSDAY.  THERE ARE
STILL SOME QUESTIONS ON THE TRACK OF THE LOW PRESSURE AND PLACEMENT
OF THE HEAVIEST PRECIPITAION, HOWEVER, ENOUGH CONFIDENCE IS THERE TO
GET THE WORD OUT EARLY.

A BROAD TROUGH OF LOW PRESSURE IS
ANTICIPATED TO BEGIN TO MOVE INTO IDAHO TUESDAY AFTERNOON AND
EVENING, WITH A SURFACE LOW PRESSURE CENTER DEVELOPING AND THEN
MOVING NORTHEAST INTO WESTERN MONTANA TUESDAY NIGHT.  THE LOW SYSTEM
WILL EVENTUALLY CUT OF FROM THE MAIN LARGE SCALE FLOW AND SETUP JUST
EAST OF GLACIER NATIONAL PARK.  BELOW ARE THE POTENTIAL IMPACTS FOR
EACH REGION.

IDAHO, CLEARWATER, LEMHI COUNTIES IN
IDAHO:

EVERYTHING IS POINTING TOWARDS MODERATE TO HEAVY RAIN TO
DEVELOP BY TUESDAY MID-AFTERNOON.  SOME SHOWERS COULD BECOME QUITE
STRONG WITH THE POSSIBILITY OF A FEW THUNDERSTORMS DEVELOPING.
HIGHEST IMPACTED AREAS WILL BE HIGHWAY 12 IN IDAHO COUNTY DUE TO THE
POTENTIAL FOR ROCK AND MUDSLIDES, AS WELL AS FOR AREAS THAT HAVE HAD
RECENT FIRE ACTIVITY ELSEWHERE IN CENTRAL IDAHO.  HEAVIEST RAIN
SHOULD BE OUT OF THESE AREAS AFTER MIDNIGHT TUESDAY NIGHT OR EARLY
WEDNESDAY MORNING.

WEST-CENTRAL AND SOUTHWESTERN MONTANA:

HEAVY
PRECIPITAION SHOULD BEGIN LATE TUESDAY AS THE SURFACE LOW MOVES
NORTHEAST.  THE HEAVIEST PRECIP WILL BE DIRECTLY UNDER THE LOW, AND
AT THIS TIME LOOKS TO MOVE OVER THE BITTERROOT/MISSOULA VALLEYS AND
THE SAPPHIRE MOUNTAINS.  THERE IS THE POTENTIAL FOR COLD AIR TO BE
PULLED DOWN TO THE SURFACE BY MODERATE TO HEAVY PRECIPITATION,
RESULTING IN WET SNOW REACHING THE VALLEY FLOOR WEDNESDAY
MORNING.

NORTHWEST MONTANA:

NORTHWEST MONTANA WILL LIKELY BE
IMPACTED THE MOST WITH THIS SYSTEM.  HEAVY WET SNOW IS EXPECTED FOR
THE GLACIER NATIONAL PARK REGION (INCLUDING MARIAS PASS), AND
POSSIBLY SOME SNOW MIXING IN WITH THE RAIN AT LOWER ELEVATIONS LIKE
WEST GLACIER AND KALISPELL.  THE LOW IS EXPECTED TO SIT EAST OF THE
DIVIDE WRAPPING MOISTURE AROUND IN THE REGION FROM WEDNESDAY INTO
THURSDAY.

SUMMARY:

IN ANYCASE HEAVY RAIN OR SNOW IS EXPECTED FOR
MOST FROM CENTRAL IDAHO TO GLACIER NATIONAL PARK.  SNOW CAN BE
EXPECTED FOR THE MOUNTAINS AND MOUNTAIN PASSES. AS FOR THE VALLEYS,
SNOW IS STILL UNCERTAIN, BUT WILL BE WATCHED CLOSELY.  FOLLOW UP
EMAILS WILL BE SENT WITH MORE SPECIFIC NUMBERS AND TIMING OF PRECIP
IN THE COMING DAYS.

THANK YOU,

NWS MISSOULA

IF YOU HAVE QUESTIONS OR CONCERNS...DO NOT HESITATE TO CALL OR
CHAT US.



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