Flood in Montana, March 14 to 16, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
901 PM MDT WED MAR 14 2007

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
UPDATE...SHOWERS HAVE EXITED NORTHEAST MONTANA FOR THE MOST PART.
SHORTWAVE THAT BROUGHT THE SHOWERS IS CURRENTLY IN SOUTHERN
SASKATCHEWAN. THERE ARE SOME LOW CLOUDS WITH THIS WAVE THAT WILL
MOVE THROUGH THE NORTHEAST PART OF THE FORECAST AREA OVERNIGHT.
WILL KEEP SKIES MOSTLY CLOUDY THERE. ELSEWHERE...THERE ARE PLENTY
OF BREAKS IN THE CLOUDS...WILL GO PARTLY CLOUDY FOR SKY COVER.
INVERTED SURFACE TROUGH IS NOW LOCATED NEAR THE NORTH DAKOTA
BORDER. THIS TROUGH WILL MOVE TO THE EAST OVERNIGHT. WILL MAKE
ADJUSTMENTS TO THE WIND FORECAST BASED ON THE MOVEMENT OF THE
TROUGH. FORRESTER

PREVIOUS SHORT TERM...
A FAST WEST TO EAST POLAR JET ACROSS THE NORTHERN TIER OF THE
U.S. WILL BECOME MORE HIGHLY AMPLIFIED BY LATE IN THE WEEK. THE
UPPER FLOW ACROSS THE LOCAL AREA WILL TURN INTO THE NORTHWEST
TONIGHT. AS AN UPPER RIDGE DEVELOPS TO OUR WEST MILDER AIR WILL
WORK BACK INTO THE AREA BY FRIDAY.

TONIGHT...A SHORTWAVE TROUGH VISIBLE ON WATER VAPOR ACROSS SOUTHERN
ALBERTA WILL RACE OFF TO THE EAST/SOUTHEAST IN A FAST JET ALOFT.  BY
MORNING MOST OF THE ENERGY ASSOCIATED WITH THE WAVE WILL BE LOCATED
ACROSS NORTH DAKOTA.  THIS WILL PUT THE CWA IN NORTHWEST FLOW ALOFT
BETWEEN THE TROUGH AND RIDGING OFF THE WEST COAST BY LATER
TONIGHT.   A SURFACE WAVE ASSOCIATED WITH THE UPPER TROUGH IN
ALBERTA WILL TRACK ACROSS THE AREA THIS EVENING AND PUSH EAST INTO
THE DAKOTAS BY MORNING.  THIS WILL SEND A WEAK COLD FRONT ACROSS THE
AREA.  ENOUGH MOISTURE...LIFT...AND INSTABILITY FOR A FEW
SHOWERS...MAINLY EARLY THIS EVENING BEFORE THE LOSS OF DAYTIME
HEATING.  CALLS TO WEATHER SPOTTERS INDICATE BOTH RAIN AND SNOW
SHOWERS...WITH MAINLY SNOW SHOWERS UNDER THE HEAVIEST RADAR
RETURNS.  ACROSS THE NORTHEAST ZONES THE CHANCE WILL LINGER A LITTLE
LONGER INTO THE NIGHT AS THIS AREA WILL BE JUST TO THE NORTHWEST OF
THE TRACK OF THE SURFACE LOW IN AN AREA WITH A BIT MORE LINGERING
MOISTURE AND LIFT.

THURSDAY...THE UPPER TROUGH IN NORTH DAKOTA CONTINUES TO PUSH AWAY
FROM THE LOCAL AREA AND JOINS FORCES WITH A TROUGH IN ONTARIO TO
CARVE OUT A BROAD TROUGH ACROSS THE GREAT LAKES.  THE UPPER RIDGE
CONTINUES TO REBOUND ALONG THE WEST COAST.  THIS WILL PUT THE AREA
IN STRONG NORTHWEST FLOW ALOFT WITH SOME SURFACE RIDGING ACROSS THE
AREA.  EXPECT A DRY DAY WITH SOME SUNSHINE AND SEASONABLY COOL
TEMPERATURES.

THURS NIGHT & FRIDAY...THE PATTERN CONTINUES TO AMPLIFY ACROSS THE
UNITED STATES.  AS JET ENERGY DIVES INTO THE GREAT LAKES IT WILL
CARVE OUT A STRONG TROUGH FROM THE GREAT LAKES INTO THE SOUTHEAST.
AT THE SAME TIME A DEEP UPPER LOW WILL DROP INTO THE GULF OF
ALASKA.  THIS WILL BUILD A STRONG RIDGE ACROSS THE WESTERN THIRD OF
THE UNITED STATES.  THE CWA WILL REMAIN IN NORTHWEST FLOW ALOFT.
500MB HEIGHTS AND 1000-500MB THICKNESS VALUES WILL CLIMB AS THE
RIDGE BUILDS IN A WARM ADVECTION PATTERN.  A WEAK LEE SIDE TROUGH
WILL LIKELY DEVELOP AND EXTEND DOWN INTO CENTRAL MONTANA.  THE FLOW
AT THE SURFACE REMAINS MOSTLY OUT OF THE SOUTHEAST WHICH WILL TEMPER
THE WARMING SOME.  WOULD EXPECT TO SEE A DECENT GRADIENT IN
TEMPERATURES FROM NORTHEAST TO SOUTHWEST ACROSS THE CWA.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
NO CHANGES OF ANY SIGNIFICANCE INTRODUCED TO PREVIOUS FORECAST
PACKAGE. LATEST ENSEMBLE GUIDANCE STILL IN AGREEMENT WITH
PROGRESSING AN UPPER RIDGE EASTWARD ACROSS MONTANA ON SATURDAY
WHILE FLATTENING IT AT THE SAME TIME. DISAGREEMENTS THEN ARISE ON THE
NEXT UPPER TROUGH FORECAST TO AFFECT THE AREA BY THE MIDDLE OF
NEXT WEEK. TOO MUCH UNCERTAINTY THIS FAR OUT TO WARRANT ANY
CHANGES WITH THIS FEATURE. MCZ

PREVIOUS DISCUSSION... THE GENERAL PATTERN OF THIS
WEEK SORT OF REPEATS ITSELF AGAIN IN THE LONG TERM...BUT WITHOUT
SUCH A LARGE OF TEMP CHANGE. A BROAD UPPER RIDGE BUILDING OVER THE
AREA DRIVES THICKNESSES ABOVE 550 DM OVER NE SAT. THIS IS NOT AS
HIGH AS THIS PAST MONDAY WHEN MUCH OF OUR AREA HIT THE 70S FOR
HIGHS...BUT BELIEVE THAT MEN NUMBERS ARE A BIT TOO COOL...SO HAVE
RAISED HIGHS. THEN A DRY COLD FRONT AGAIN MOVES ACROSS THE AREA
SUNDAY FROM THE NORTH TO BRING A COUPLE DAYS OF COOLER WEATHER. NO
UPPER SUPPORT FOR PRECIP. THE FRONT IS ASSOCIATED WITH ANOTHER
ARCTIC HIGH CENTER THAT IS MOVING WELL TO OUR NORTH IN AN ESE
TRACK ACROSS CANADA. MODELS ARE IN GOOD AGREEMENT WITH THE
PATTERN..EXCEPT THE CMC WHICH BARELY BRUSHES OUR NORTH WITH THE
FRONT SUNDAY.

LATER IN THE PERIOD THE RIDE MOVES EAST WITH A BROAD UPPER TROUGH
APPROACHING FROM THE WEST. NE MT GOES INTO A SW FLOW ALOFT
BRINGING A WARMER AIRMASS INTO THE AREA AGAIN. A SHORTWAVE WEATHER
SYSTEM ARRIVES TUE NIGHT...FOR ABOUT THE ONLY SIGNIFICANT THREAT OF
ANY PRECIP DURING THE PERIOD. THICKNESSES AND 850 MB TEMPS
INDICATE THIS WILL TAKE THE FORM OF LIGHT RAIN. SIMONSEN

&&

.AVIATION...
A FEW AREAS OF BROKEN CEILINGS AROUND 1K FT AGL N OF THE MISSOURI
RIVER...AND EAST OF GLASGOW THIS EVENING. ANOTHER MUCH LARGER
AREA OF MVFR OVERCAST CEILINGS AROUND 1K FT AGL IN SW SK WILL
MOVE SE ACROSS MOST OF THE FLOW OVERCAST WILL CLEAR OUT OF THE
AREA BY MID-MORNING THOUGH...LEAVING VFR CONDITIONS WITH JUST
SCATTERED CLOUDS. SIMONSEN

&&

.HYDROLOGY...
THE WARM WEATHER THE LAST SEVERAL DAYS HAS NOW MELTED MOST OF THE
SNOW ACROSS NORTHEAST MONTANA.  SMALL STREAMS AND CREEKS CONTINUE
TO RUN A LITTLE HIGHER THAN NORMAL...BUT ALL ARE BEHAVING SO FAR.
THE BIG MUDDY CREEK REMAINS CLOSE TO FLOOD STAGE...BUT CALLS TO
SPOTTERS IN THE AREA INDICATE THAT THE WATER LEVELS ARE NOW
STARTING TO COME DOWN. WHAT LITTLE SNOW IS LEFT TO MELT HAS
SLOWED THANKS TO COOLER TEMPERATURES ACROSS THE REGION. THE ICE
CONTINUES TO BREAK UP ON THE YELLOWSTONE RIVER BETWEEN GLENDIVE
AND SIDNEY AND THE MILK RIVER BETWEEN TAMPICO...GLASGOW AND
NASHUA. THE RIVER GAGE AT GLASGOW IS UP ABOUT 3 FEET SINCE
YESTERDAY AFTERNOON...AND THERE WILL LIKELY CONTINUE TO BE RISES
DURING THE NEXT FEW DAYS...BUT NO FLOODING PROBLEMS ARE
ANTICIPATED AT THIS TIME. GFF/RAE/CB

&&

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

&&

WEATHER.GOV/GLASGOW