Special Weather Statement, NWS Missoula, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
222 PM MDT FRI AUG 7 2009

.DISCUSSION...A LOW PRESSURE SYSTEM WILL CONTINUE TO IMPACT
NORTH-CENTRAL IDAHO AND WESTERN MONTANA TONIGHT AND INTO SATURDAY.
THE LOW CENTER...CURRENTLY LOCATED OVER CENTRAL IDAHO...WILL BE
MOVING SLOWLY EASTWARD ACROSS SOUTHEAST IDAHO TONIGHT. THE PRIMARY
PRECIPITATION BAND EXTENDS FROM NORTHWEST MONTANA...ACROSS THE
IDAHO PANHANDLE INTO NORTHEAST OREGON. THIS BAND HAS BEEN
WEAKENING THROUGHOUT THE DAY TODAY AND WILL CONTINUE TO DO SO
TONIGHT. HOWEVER...CONVECTIVE SHOWERS HAVE BEEN DEVELOPING ACROSS
WEST-CENTRAL MONTANA /CLOSER TO THE CENTER OF THE LOW SYSTEM/ AND
ARE BECOMING GREAT RAIN PRODUCERS WITH PEA-SIZED HAIL ALSO BEING
REPORTED WITH SOME OF THE STRONGER STORMS. ALL THIS ACTIVITY WILL
BE DECREASING LATE TONIGHT AND SATURDAY AS THE LOW SYSTEM WEAKENS
AND TRACKS INTO WYOMING BY SATURDAY. A RIDGE OF HIGH PRESSURE WILL
BE BUILDING INTO THE NORTHERN ROCKIES REGION SATURDAY NIGHT. WE
EXPECT PRECIPITATION TO END AND CLOUDS TO DECREASE SATURDAY NIGHT.

SUNDAY THROUGH TUESDAY NIGHT...AS THE UPPER LOW MOVES COMPLETELY EAST
AND OUT OF THE REGION...CONDITIONS SHOULD BEGIN TO DRY FROM WEST TO
EAST AS BRIEF RIDGING BUILDS ACROSS THE NORTHERN ROCKIES SUNDAY INTO
MONDAY. FLOW WILL GRADUALLY TURN MORE WESTERLY AND REMAIN SOMEWHAT
FEATURELESS THROUGH MIDWEEK...HELPING CONDITIONS TO STAY FAIRLY
DRY AND TEMPERATURES TO RETURN TO MORE SEASONAL VALUES.

WEDNESDAY THROUGH THE WEEKEND...NEAR NORMAL TEMPERATURES AND
MOSTLY DRY FORECAST WERE ALSO CONTINUED THROUGH THE END OF NEXT
WEEK. MODELS INDICATE A DRY WEST-SOUTHWESTERLY FLOW THROUGH MID
WEEK. BOTH THE GFS AND ECMWF TRY TO DEVELOP ANOTHER TROUGH/CUT OFF
SOLUTION OFF THE COAST TOWARDS THE END OF NEXT WEEK...WILL WATCH
THEIR DEVELOPMENT OF THIS FEATURE...BUT MADE NO MAJOR CHANGES TO
EXTENDED FORECAST.

&&

.AVIATION...WIDESPREAD RAIN SHOWERS...WITH SOME EMBEDDED THUNDER...WILL
CONTINUE ACROSS WEST CENTRAL MONTANA THROUGH THE EARLY EVENING
HOURS. THE CENTER OF THE LOW PRESSURE SYSTEM RESPONSIBLE FOR THE
RAIN AND THUNDER TODAY IS MOVING EASTWARD THROUGH SOUTHWEST
MONTANA AND SOUTH CENTRAL IDAHO. SOME WRAP AROUND PRECIP CAN BE
EXPECTED OVERNIGHT FRIDAY AS THE LOW CONTINUES TO THE EAST.
HEAVIEST PRECIP AND IMPACTS TO TERMINAL OPERATIONS CAN BE EXPECTED
AT KMSO THROUGH 00Z. VICINITY SHOWERS WILL ALSO BE POSSIBLE NEAR
KSMN...KBTM AND KGPI THROUGH THE EVENING. LOW CLOUDS AND RAIN
SHOWERS COULD OBSCURE MOUNTAIN PEAKS AND PASSES THROUGH THE
AFTERNOON. SCATTERED SHOWERS WILL LINGER OVER THE HIGHER TERRAIN
BEHIND THE EXITING LOW THROUGH SATURDAY AM.

&&

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

SHORT TERM...MSJ
LONG TERM....ALLEGRETTO/NOLTE
AVIATION...NOLTE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MISSOULA MT
401 AM MDT FRI AUG 7 2009

IDZ006>008-MTZ001>003-072345-
SOUTHERN CLEARWATER MOUNTAINS-OROFINO/GRANGEVILLE REGION-
LOWER HELLS CANYON/SALMON RIVER REGION-KOOTENAI/CABINET REGION-
WEST GLACIER REGION-FLATHEAD/MISSION VALLEYS-
401 AM MDT FRI AUG 7 2009 /301 AM PDT FRI AUG 7 2009/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
IDAHO AND NORTHWEST MONTANA.

FOR THE LATEST INFORMATION ON WATCHES...WARNINGS AND ADVISORIES...GO
TO WEATHER.GOV/MISSOULA.

.DAY ONE...TODAY AND TONIGHT

A FLOOD WATCH IS IN EFFECT FOR TODAY.

A STRONG UPPER LOW PRESSURE SYSTEM IS SLOWLY MOVING TO THE EAST
AND WILL REMAIN OVER THE REGION THROUGH SATURDAY. AREAS OF MODERATE TO
HEAVY RAIN ARE EXPECTED. BETWEEN THIS MORNING AND SATURDAY
AFTERNOON...MANY AREAS MAY SEE UP TO ONE INCH OF RAIN IN THE
VALLEYS...WITH SOME OF THE HIGHER TERRAIN POSSIBLY SEEING TWO TO
THREE INCHES. PONDING OF WATER ON ROADWAYS AND LOW LYING AREAS ARE
POSSIBLE IN AREAS OF HEAVY RAIN. ALONG WITH THE HEAVY
PRECIPITATION...TEMPERATURES SHOULD AVERAGE 15 TO 20 DEGREES BELOW
NORMAL FOR THIS TIME OF YEAR.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

A WEAK RIDGE WILL BUILD INTO REGION ON SUNDAY BEHIND THE EXITING
LOW PRESSURE SYSTEM. THIS WILL BRING DRIER WEATHER AND
TEMPERATURES CLOSER TO SEASONAL AVERAGES.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

IDZ005-009-010-MTZ004>007-043-072345-
NORTHERN CLEARWATER MOUNTAINS-WESTERN LEMHI COUNTY-
EASTERN LEMHI COUNTY-LOWER CLARK FORK REGION-
MISSOULA/BITTERROOT VALLEYS-BITTERROOT/SAPPHIRE MOUNTAINS-
BUTTE/BLACKFOOT REGION-POTOMAC/SEELEY LAKE REGION-
401 AM MDT FRI AUG 7 2009 /301 AM PDT FRI AUG 7 2009/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
IDAHO AND WEST CENTRAL MONTANA.

.DAY ONE...TODAY AND TONIGHT

A STRONG UPPER LOW PRESSURE SYSTEM IS SLOWLY MOVING TO THE EAST
AND WILL REMAIN OVER THE REGION THROUGH SATURDAY. AREAS OF MODERATE TO
HEAVY RAIN ARE EXPECTED. BETWEEN THIS MORNING AND SATURDAY
AFTERNOON...MANY AREAS MAY SEE UP TO ONE INCH OF RAIN IN THE
VALLEYS...WITH SOME OF THE HIGHER TERRAIN POSSIBLY SEEING TWO TO
THREE INCHES. PONDING OF WATER ON ROADWAYS AND LOW LYING AREAS ARE
POSSIBLE IN AREAS OF HEAVY RAIN. ALONG WITH THE HEAVY
PRECIPITATION...TEMPERATURES SHOULD AVERAGE 15 TO 20 DEGREES BELOW
NORMAL FOR THIS TIME OF YEAR.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

A WEAK RIDGE WILL BUILD INTO REGION ON SUNDAY BEHIND THE EXITING
LOW PRESSURE SYSTEM. THIS WILL BRING DRIER WEATHER AND
TEMPERATURES CLOSER TO SEASONAL AVERAGES.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
948 PM MDT FRI AUG 7 2009

IDZ006-007-080430-
OROFINO/GRANGEVILLE REGION-SOUTHERN CLEARWATER MOUNTAINS-
848 PM PDT FRI AUG 7 2009

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL IDAHO COUNTY UNTIL 930 PM
PDT...

AT 842 PM PDT...STORM SPOTTERS REPORTED THREE COLD AIR FUNNELS NEAR
GRANGEVILLE...NEARLY STATIONARY.

THESE COLD AIR FUNNELS ARE NOT...REPEAT...ARE NOT ANTICIPATED TO
REACH THE GROUND.

LAT...LON 4590 11563 4568 11612 4592 11624 4615 11580
TIME...MOT...LOC 0343Z 329DEG 3KT 4588 11608

ZUMPFE