000
FXUS65 KGGW 180244
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
844 PM MDT MON JUN 17 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY...
UPDATE...A FEW THUNDERSTORMS HAVE FIRED OVER THE ROCKY MOUNTAINS
THIS EVENING. WHILE... THE STORMS ARE MOVING EAST... THEY SHOULD
DISSIPATE BEFORE REACHING THE STABLE AIR IN NORTHEAST MONTANA.
WILL UPDATE THE FORECAST TO INCREASE CLOUD COVER TO PARTLY CLOUDY
IN SOME AREAS AS MID AND HIGH CLOUDS LEFT OVER FROM THE STORMS
WILL DRIFT OVER THE FORECAST AREA OVERNIGHT. REST OF FORECAST
LOOKS REASONABLE. FORRESTER

PREVIOUS SHORT TERM... TONIGHT UPPER RIDGING WILL BUILD INTO
NORTHEAST MONTANA AHEAD OF A PACIFIC LOW PRESSURE SYSTEM OFF THE
COAST OF THE PACIFIC NORTHWEST. THIS RIDGING WILL KEEP CONDITIONS
MOSTLY CLEAR TONIGHT...WITH MILD OVERNIGHT LOWS. SOUTHEAST WINDS
WILL BEGIN TO PICK UP IN RESPONSE TO A DEEPENING SURFACE TROUGH
OVER WESTERN MONTANA.

TUESDAY SOUTHEASTERLY LOW LEVEL FLOW WILL CONTINUE TO
INCREASE...AND A LAKE WIND ADVISORY MAY BE NEEDED FOR FORT PECK LAKE.
THIS FLOW WILL ALSO BRING IN MOISTURE SOURCED OUT OF THE GULF OF
MEXICO. TEMPERATURES WILL WARM INTO THE LOW TO MID 80S UNDER THE
INFLUENCE OF THE UPPER RIDGE. WEAK DISTURBANCES AHEAD OF THE
PACIFIC LOW COULD TRIGGER A FEW STORMS ACROSS CENTRAL
MONTANA...THAT COULD DRIFT INTO NORTHEAST MONTANA DURING THE LATE
AFTERNOON OR EVENING. SOME STORMS COULD BE ON THE STRONG SIDE
GIVEN A MARGINALLY FAVORABLE SHEAR PROFILE.

TUESDAY NIGHT MAY SEE SOME LINGERING THUNDERSTORMS
OVERNIGHT...ESPECIALLY ACROSS THE WEST AND SOUTHEAST WHERE SOME
WEAK QG FORCING MAY KEEP STORMS ALIVE OVERNIGHT. OTHERWISE EXPECT
ANOTHER ROUND OF MILD OVERNIGHT LOW TEMPS THANKS TO THE DOMINANCE
OF THE UPPER RIDGE.

WEDNESDAY CONTINUES TO LOOK FAVORABLE FOR STRONG TO SEVERE
THUNDERSTORMS. THE PACIFIC LOW WILL PUSH INTO THE COLUMBIA RIVER
BASIN...INCREASING THE SOUTHWESTERLY FLOW ALOFT OVER THE TREASURE
STATE. THE VERY MOIST LOW LEVEL SOUTHEASTERLY FLOW WILL CONTINUE TO
PUMP IN GULF MOISTURE...RAISING DEWPOINTS TO NEAR 60 DEGREES. EXPECT
STORMS TO INITIALLY FIRE OVER THE CENTRAL MONTANA MOUNTAINS BY MID
AFTERNOON BEFORE DRIFTING TO THE NORTH AND EAST ACROSS NORTHEAST
MONTANA. WITH AMPLE MOISTURE...GOOD SHEAR PROFILES...AND
INSTABILITY LARGE HAIL...STRONG WINDS...AND HEAVY RAINFALL WILL BE
POSSIBLE WITH STORMS THAT DEVELOP.


.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
THE EXTENDED PERIOD BEGINS WEDNESDAY EVENING WITH A CLOSED OFF
UPPER LOW CENTERED OVER COLUMBIA RIVER GORGE. THE JET AT THE
BASE OF THE TROUGH WILL EJECT PACIFIC MOISTURE INTO MONTANA...
WHERE IT WILL MEET AN UNSTABLE ENVIRONMENT. A SURFACE TROUGH IN
THE LEE OF THE NORTHERN ROCKIES WILL DIRECT A SOUTHEASTERLY FLOW
OF SURFACE MOISTURE INTO NEMONT...RESULTING IN DEW POINTS IN THE
MID 50S. VERTICAL SHEAR WILL BE MODERATE...BUT SURFACE BASED CAPE
AT 00Z THURSDAY WILL RANGE AROUND 2500 TO 3000 J/KG AND LIFTED
INDEX PARAMETERS OF AROUND -6C TO -7C SUGGEST A LIKELY POTENTIAL
FOR SEVERE THUNDERSTORMS DEVELOPING...WITH LARGE HAIL. LATER IN
THE EVENING THIS COULD EVOLVE INTO MORE OF A STRATIFORM...MODERATE
TO HEAVY...RAIN EVENT AFTER THE COLD FRONT PASSES THROUGH THE
AREA.

THE UPPER LOW CENTER DRIFTS OVER THE NORTHERN ROCKIES ON THURSDAY
POSSIBLY DRY-SLOTTING MOST OF NEMONT. HOWEVER CONDITIONS BEHIND
THE FRONT SHOULD RUN AROUND 10F DEGREES COOLER THAN THOSE OF
WEDNESDAY.

THE LOW REMAINS STALLED OUT OVER NORTHERN ROCKIES WHILE CONTINUING
TO DIRECT A STRONG SOUTHWESTERLY FLOW ALOFT INTO NEMONT...BRINGING
MORE CHANCES FOR RAIN SHOWERS AND THUNDERSTORMS. THEN FINALLY ON
SATURDAY THE LOW BEGINS TO MOVE EAST THEN LIFT NORTH AS IT RUNS
OVER NEMONT...BRING MORE RAIN.

THE EFFECTS OF THE STORM BEGIN TO WAIN OVER NEMONT ON SUNDAY AS AN
UPPER LEVEL RIDGE DEVELOPS OVER THE NORTHERN ROCKIES TO BRING
WARMER AND DRIER CONDITIONS BY EARLY NEXT WEEK.

WITH MODELS AGREEING AND CONSISTENT...MADE ONLY MINOR
TWEAKS...MAINLY TO BLEND WITH NEIGHBORS. SCT

PREVIOUS DISCUSSION...
CLOSED LOW OFF THE PACIFIC NORTHWEST EXPECTED TO ROTATE SLOWLY
THROUGH THE NORTHERN ROCKIES LATE IN THE WEEK BEFORE LIFTING INTO
CENTRAL CANADA EARLY NEXT WEEK. UNSETTLED WEATHER WITH GENERALLY
COOL AND WET CONDITIONS EXPECTED FOR MOST OF THE PERIOD.

AS THE UPPER TROF MOVED INTO THE NORTHERN ROCKIES...CONDITIONS
FAVORABLE FOR SEVERE WEATHER DEVELOP FOR WEDNESDAY NIGHT. PLENTY
OF MOISTURE AVAILABLE WITH PRECIPITABLE WATER OF OVER AN INCH SO
LOCALLY HEAVY RAIN ALSO POSSIBLE WITH STORMS.

A SECOND SHORTWAVE SPINS ACROSS THE STATE ON SATURDAY. CONDITIONS
NOT A FAVORABLE FOR SEVERE WEATHER BUT HEAVY RAIN WILL AGAIN BE A
POSSIBILITY. EBERT


&&

.AVIATION...
VFR.

LIGHTS SOUTHEAST WINDS TONIGHT INCREASING TO 10 TO 20 KTS
SUSTAINED AFTER SUNRISE THROUGH TOMORROW AFTERNOON. GAH

&&

.HYDROLOGY...
A FLOOD WARNING REMAINS IN EFFECT FOR THE MILK RIVER NEAR GLASGOW.
THE LATEST GUIDANCE FROM THE RIVER FORECAST CENTER SUGGESTS THE
MILK RIVER NEAR GLASGOW WILL POSSIBLY GO BELOW FLOOD STAGE BY
THURSDAY.


&&

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

&&

$$

WEATHER.GOV/GLASGOW