Hail and Damaging Winds in Montana, August 10 to 11, 2008

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
935 AM MDT SUN AUG 10 2008

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
ONLY UPDATE WAS TO TAILOR MORNING WINDS SOME WHILE BUMPING UP
AFTERNOON CLOUD COVER AHEAD OF AN IMPULSE EXITING NORTHWEST
WYOMING. DESPITE RATHER MARGINAL BULK SHEAR...THE MODIFIED 12Z GGW
SOUNDING REMAINS IMPRESSIVE CONSIDERING THE LACK OF LOW LEVEL
CAPPING...DEPTH OF POSITIVE ENERGY AND PRECIPITABLE WATER VALUES.
SURFACE TROF IS ALREADY BISECTING THE CWA FROM JUST WEST OF OPHEIM
SOUTHEAST TO TERRY WITH THE MAIN SURFACE LOW WELL TO THE NORTH-
NORTHWEST. BEST INSTABILITY SHOULD RESIDE OVER THE EASTERN ZONES
THIS AFTERNOON ALONG/AHEAD OF THE TROF WITH LESSER VALUES FARTHER
WEST AHEAD OF THE COLD FRONT TONIGHT. WOULD EXPECT SOME ACTIVITY TO
FIRE THIS AFTERNOON AHEAD OF THE IMPULSE IN WYOMING...BUT BEST
COVERAGE OF STORMS AND DECENT RAINS SHOULD STILL BE OVERNIGHT AS
THE STRONGER UPPER SUPPORT ARRIVES. MCZ

PREVIOUS SHORT TERM DISCUSSION...
IT APPEARS THAT THE SMALL ROUND OF SEVERE THUNDERSTORMS LAST
EVENING WAS JUST A PRIMER FOR TODAY AND TONIGHT. PRE-FRONTAL
SURFACE TROF STILL LOITERING ACROSS EASTERN INTO CENTRAL MONTANA
WITH THE COLD FRONT FARTHER WEST BACK IN THE VICINITY OF CUT BANK.
CLOSED AND WOUND UP UPPER LOW SPINNING OVER SOUTHERN BRITISH
COLUMBIA. THUS SOUTHWEST FLOW ALOFT ACROSS THE AREA ONCE AGAIN
TODAY WITH A BIT MORE UPPER SUPPORT EXPECTED LATER TODAY AND THIS
EVENING AS THE LOW DRAWS A BIT CLOSER AND STRONGER ENERGY EJECTS
OUR WAY FROM IT. LAPSE RATES STEEPEN THIS AFTERNOON AND ATMOSPHERE
DESTABILIZES CONSIDERABLY. LOW-LEVEL THETA-E RIDGE EXPECTED
DIRECTLY OVER THE CWA LATER THIS AFTERNOON WITH SURFACE- BASED
CAPES OF 1600-2200 J/KG. THUS ONCE STORMS GET GOING THERE IS NO
REASON NOT TO EXPECT A DECENT ROUND OF SEVERE WEATHER. WITH FEED
OF SOUTHWEST MONSOONAL MOISTURE EXPECTED TO CONTINUE TODAY PRIOR
TO THE FRONTAL PASSAGE TONIGHT...SOME STORMS ARE LIKELY TO PRODUCE
SOME HEAVY RAIN ALONG WITH THE POSSIBILITY OF LARGE HAIL AND VERY
STRONG WIND. THIS MORNING SOME LINGERING CONVECTION COULD BE HAD
ACROSS THE SOUTHERN AND EASTERN PORTIONS OF THE CWA BEFORE THE
MAIN EVENT THIS AFTERNOON AND EVENING. TEMPERATURES AGAIN ON THE
WARM AND HUMID SIDE TODAY WITH READINGS PEAKING AROUND 90 AND
DEWPOINTS RANGING FROM MID 50 TO LOWER 60S. COLD FRONT MOVES THRU
TONIGHT AND BRINGS SOME LIFT OF ITS OWN TO KEEP SHOWERS AND STORMS
GOING. ALTHO BEST TIME PERIOD FOR SEVERE WILL BE LATER THIS
AFTERNOON AND EVENING...SEVERE STORMS CANNOT BE DISCOUNTED FOR
TONIGHT FROM AROUND GLASGOW EAST...ALTHO SUSPECT THE OVERNIGHT
WILL FEATURE SOME DECENT RAIN TOTALS. UPPER LOW MOVES INTO ALBERTA
MONDAY AND THE ASSOCIATED TROF SWINGS THRU THE AREA AND HELPS KICK
OFF SOME SHOWERS AND STORMS...ALTHO THE MOISTURE CONTENT OF THE
ATMOSPHERE WILL HAVE GONE DOWN SIGNIFICANTLY AS DRIER AIR MOVES IN
BEHIND THE FRONT TONIGHT. TEMPERATURES MONDAY SOME 10 DEGREES OR
SO COOLER THAN SUNDAY WITH MOST READINGS PEAKING AROUND 80. THE
UPPER LOW THEN CONTINUES MERRILY EAST MONDAY NIGHT AND TUESDAY AND
IS EXPECTED TO BE ABOUT OVER THE CENTRAL SASKATCHEWAN/MANITOBA
BORDER BY LATE TUESDAY AFTERNOON. MONDAY NIGHT WILL BE MUCH COOLER
AND DRIER THAN THE WARM NIGHT EXPECTED TONIGHT...WITH LOWS MONDAY
NIGHT SOME 10-15 DEGREES COOLER. DRIER AIR COMING IN FROM THE WEST
ON THE HEELS OF THE WEST TO NORTHWEST FLOW AROUND THE LOW AS IT
PASSES TO OUR NORTH WILL MAKE FOR A DRY MONDAY NIGHT AND TUESDAY.
TEMPERATURES TUESDAY A FEW DEGREES WARMER THAN MONDAY BUT STILL
BELOW NORMAL FOR THIS TIME OF YEAR WITH THE UPPER LOW POISED TO
OUR NORTH KEEPING UPPER HEIGHTS/THICKNESS VALUES SUPPRESSED AND
WARMER AIR AT BAY TO OUR SOUTHWEST.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
UPPER LOW OVER BRITISH COLUMBIA...THAT IS CURRENTLY DRIVING THE
SOUTHWEST FLOW...WILL MOVE OUT OVER THE PRAIRIE PROVINCES TO BEGIN
THE EXTENDED PERIOD. GFS AND GEM PLACE THE LOW IN CENTRAL
SASKATCHEWAN TUESDAY NIGHT BUT THE 12Z ECMWF PLACES THE LOW IN
NORTH DAKOTA. THEREFORE NOT A LOT OF CONFIDENCE INITIALLY ON
PLACEMENT OF LOW...BASED ON ECMWF. HOWEVER 00Z ECMWF BECAME
SIMILAR TO THE GFS AND GEM SOLUTIONS. THEREFORE FORECAST WILL BE
BASED ON A BLEND OF GFS...GEM AND ECMWF. WILL KEEP TUESDAY NIGHT
AND WEDNESDAY POP GRIDS BELOW SLIGHT CHANCE. THE LOW WILL INDUCE A
SHORTWAVE ACROSS THE ZONES WEDNESDAY NIGHT/THURSDAY BEFORE A VERY
AMPLIFIED UPPER RIDGE BUILDS UP OVER THE WEST. THIS FAST MOVING
SHORTWAVE COULD INITIATE A FEW STORMS AND IS THE BEST CHANCE FOR
SHOWERS. SO WILL TWEAK POP GRIDS SLIGHTLY TO MENTION SLIGHT
CHANCE. THE REMAINDER OF THE EXTENDED PERIOD UNDER A NORTHERLY TO
NORTHWESTERLY FLOW WITH THE RIDGE TO THE WEST. THIS WILL MODERATE
MAXIMUM TEMPERATURES AND MAINTAIN SMALL CHANCES FOR CONVECTION.
THERE IS NOT MUCH REASON TO MAKE MANY CHANGES TO THE EXTENDED
PERIOD FOR NOW WHILE MODELS CONTINUE TO SETTLE. SCT

&&

.AVIATION...
EASTERLY WINDS BETWEEN 10 AND 15 KTS WILL BE MAINTAINED ACROSS
THE TAF SITES AHEAD OF A SURFACE TROUGH THAT ENTERS THE REGION
THIS AFTERNOON PROMOTING MORE THUNDERSTORMS...SOME OF WHICH
COULD BE SEVERE. COLD FRONT TRAVELS EAST OVER THE AREA TONIGHT
INCREASING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. WIND BEHIND
THE FRONT WILL SHIFT TO THE NORTHWEST AT 10-20 KT. SCT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

WEATHER.GOV/GLASGOW

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GLASGOW MT
344 AM MDT SUN AUG 10 2008

MTZ016>027-059>062-110945-
CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-
DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-GARFIELD-MCCONE-
RICHLAND-DAWSON-PRAIRIE-WIBAUX-NORTHERN PHILLIPS-
SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT-
344 AM MDT SUN AUG 10 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS WILL DEVELOP LATE THIS AFTERNOON OR EARLY EVENING AND
PERSIST THROUGH MUCH OF THE NIGHT. SOME OF THESE STORMS ARE LIKELY
TO BECOME SEVERE AND PRODUCE LARGE HAIL AND/OR DAMAGING WIND.
SOME STORMS WILL ALSO PROVIDE LOCALLY HEAVY RAINFALL. SINCE THE
STORMS ARE NOT EXPECTED TO BE FAST-MOVING...THERE IS FLASH-FLOOD
POTENTIAL.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
1242 PM MDT SUN AUG 10 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1000 AM     HAIL             32 WNW TERRY            46.97N 105.94W
08/09/2008  E1.00 INCH       PRAIRIE            MT   TRAINED SPOTTER

&&

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PRELIMINARY LOCAL STORM REPORT...CORRECTION FOR TIME OF REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
1242 PM MDT SUN AUG 10 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1000 PM     HAIL             32 WNW TERRY            46.97N 105.94W
08/09/2008  E1.00 INCH       PRAIRIE            MT   TRAINED SPOTTER

&&

BB