Severe Thunderstorm Warning 4, NWS Glasgow, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
257 PM MDT SAT MAY 25 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
AN UPPER LOW OVER THE PACIFIC NORTHWEST WILL DRIVE A SOUTHWEST FLOW
ALOFT THROUGH THE SHORT TERM. DISTURBANCES IN THIS FLOW WILL
INTERACT WITH LOW LEVEL MOISTURE AND A STALLED SURFACE FRONT OVER
NORTHEAST MONTANA....CREATING EXCELLENT POTENTIAL FOR SHOWERS AND
THUNDERSTORMS INTO MEMORIAL DAY.

AS OF 1300 SHOWERS AND THUNDERSTORMS ARE JUST BEGINNING TO DEVELOP
ACROSS SOUTHEAST MONTANA. EXPECT STORMS TO CONTINUE TO INITIATE AS
WE GET INTO THE AFTERNOON...MAINLY FURTHER WEST NEAR THE
MUSSELSHELL RIVER. STORMS WILL SPREAD TO THE NORTH AND EAST AS WE
GET INTO THE LATE AFTERNOON AND EVENING HOURS. WITH AMPLE LOW
LEVEL MOISTURE AND SHEAR PROVIDED BY SOUTHEASTERLY SURFACE FLOW
OUT OF THE DAKOTAS STORMS WILL BE CAPABLE OF PRODUCING THE GAMUT
OF SEVERE WEATHER INCLUDING LARGE HAIL...STRONG WINDS...AND
POSSIBLY EVEN ISOLATED TORNADOES. BY LATE EVENING THE SEVERE
THREAT WILL HAVE SUBSIDED...BUT WIDESPREAD SHOWERS WITH EMBEDDED
THUNDER ARE EXPECTED TO CONTINUE OVERNIGHT.

SUNDAY AFTERNOON AND EVENING WILL AGAIN BRING THE POTENTIAL FOR
STRONG TO SEVERE THUNDERSTORMS ACROSS NORTHEAST MONTANA AS THE
OVERALL WEATHER PATTERN REMAINS VERY SIMILAR TO THIS AFTERNOON...WITH MOIST
LOW LEVEL SOUTHEAST FLOW AND A STALLED FRONTAL BOUNDARY. AGAIN
LATE SUNDAY EVENING THE SEVERE THREAT WILL END AS STORMS CHEW
THROUGH AVAILABLE SURFACE BASED INSTABILITY...BUT GOOD POTENTIAL
FOR CONTINUED SHOWER ACTIVITY WILL REMAIN OVERNIGHT.

MONDAY THE BEST POTENTIAL FOR STRONG TO SEVERE CONVECTION WILL LIE
ACROSS THE SOUTHEAST AS THE SURFACE FEATURE PUSHES EASTWARD. A
STRONG DISTURBANCE WILL PUSH THROUGH IN THE SOUTHWEST FLOW
ALOFT...CREATING THE POTENTIAL FOR WIDESPREAD SHOWERS AND
THUNDERSTORMS ACROSS THE REGION. GILCHRIST

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...

DUE TO THE ONSET OF STRONG TO SEVERE THUNDERSTORMS SETTING UP
ACROSS THE REGION...NO ADJUSTMENTS WERE MADE TO THE CURRENT LONG
TERM FORECAST. BMICKELSON

PREVIOUS LONG TERM DISCUSSION...THE UPPER TROUGH THAT WILL BEGIN
TO AFFECT THE REGION THIS WEEKEND WILL CONTINUE TO HAVE AN
INFLUENCE THROUGH NEXT WEEK. THE UPPER CLOSED LOW WILL SLOWLY
CHURN SHORTWAVE ENERGY OUT THROUGH THE WEEKEND BEFORE AN UPPER JET
MAX OFF THE PACIFIC BEGINS TO DIG THE UPPER TROUGH FURTHER SOUTH
AND EAST INTO THE DESERT SOUTHWEST ON TUESDAY. WHEN THIS
HAPPENS...A SHORTWAVE TROUGH WILL SPLIT OFF THE MAIN FLOW INTO
CANADA...AND LEAVE THE REGION OVER BRIEF SHORT RIDGING LATE
TUESDAY INTO WEDNESDAY. THE BRIEF RIDGING PERIOD WILL BE JUST
ABOUT THE ONLY BREAK FROM CONTINUED CHANCES FOR PRECIP FOR THE
REMAINDER OF THE LONG TERM.

THE UPPER JET MAX WILL CONTINUE TO PUSH THE TROUGH TO HAVE A MORE
NEGATIVE TILT WITH EACH DAY...BEFORE THE JET MAX FINALLY
PROGRESSES THROUGH THE BASE OF THE TROUGH BY FRIDAY AND BEGINS
MOVING FURTHER EASTWARD. THIS WILL CONTINUE TO PLACE THE REGION
OVER FAVORABLE PRECIP CHANCES FOR JUST ABOUT ALL OF NEXT WEEK. BY
NEXT WEEKEND...THE GFS AND ECMWF DISAGREE SLIGHTLY AS THE GFS
WANTS TO QUICKLY ERODE BRIEF RIDGING AND ALLOW ANOTHER PACIFIC
NORTHWEST LOW TO BRING MORE PRECIP. THE ECMWF WANTS TO KEEP
RIDGING AROUND A BIT LONGER...AND HAVE A CLOSED LOW POSSIBLY RIDE
DOWN THE PACIFIC COAST. EITHER WAY...BEFORE THAT OCCURS...IT
APPEARS A WET AND UNSETTLED PATTERN IS IN STORE FOR THE LONG TERM.
BARNWELL

&&

.AVIATION...

VFR CONDITIONS TO BEGIN WITH...BUT WIDESPREAD CONVECTIVE ACTIVITY
WILL DEVELOP AROUND MID DAY OR EARLY THIS AFTERNOON.
INITIALLY...IFR CONDITIONS OR WORSE WILL BE LIKELY FOR KGDV AND
KSDY DURING THE AFTERNOON HOURS AMID STRONG TO SEVERE
THUNDERSTORMS WITH GUSTY WINDS AND LARGE HAIL POSSIBLE...WHICH
WILL SPREAD TO ALL REMAINING TAF SITES THROUGH TONIGHT AND
POSSIBLY INTO THE EARLY MORNING HOURS ON SUNDAY. BMICKELSON

&&

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

&&

WEATHER.GOV/GLASGOW

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GLASGOW MT
212 PM MDT SAT MAY 25 2013

MTZ016>024-059>062-260400-
CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-
DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-GARFIELD-MCCONE-
RICHLAND-NORTHERN PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY-
EASTERN ROOSEVELT-
212 PM MDT SAT MAY 25 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

LOW LEVEL SOUTHEAST WINDS WILL BRING MOIST AIR FROM THE GULF OF
MEXICO TOWARD NORTHEAST MONTANA TODAY. MEANWHILE...THERE WILL BE
A STATIONARY FRONT OVER PHILLIPS AND PETROLEUM COUNTIES ALONG
WITH UPPER LEVEL DISTURBANCES IN SOUTHWEST FLOW ALOFT. THIS
COMBINATION WILL MAKE SHOWERS AND THUNDERSTORMS LIKELY THIS
AFTERNOON AND TONIGHT OVER MOST OF NORTHEAST MONTANA. SOME STORMS
MAY BECOME SEVERE EAST OF A OPHEIM TO HINSDALE TO JORDAN LINE THIS
AFTERNOON AND EVENING WITH LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE THREAT FOR SEVERE WEATHER WILL DEVELOP AGAIN ON SUNDAY
AFTERNOON ACROSS ALL OF NORTHEAST MONTANA AS THE WEATHER PATTERN
REMAINS LARGELY UNCHANGED.

.SPOTTER INFORMATION STATEMENT...

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

MTZ025>027-260400-
DAWSON-PRAIRIE-WIBAUX-
212 PM MDT SAT MAY 25 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

LOW LEVEL SOUTHEAST WINDS WILL BRING MOIST AIR FROM THE GULF OF
MEXICO TOWARD NORTHEAST MONTANA TODAY. MEANWHILE...UPPER LEVEL
DISTURBANCES IN A SOUTHWEST FLOW ALOFT WILL CREATE EXCELLENT
POTENTIAL FOR SEVERE THUNDERSTORMS...WITH LARGE HAIL...DAMAGING
WINDS...AND ISOLATED TORNADOES POSSIBLE. A TORNADO WATCH IS IN
EFFECT UNTIL 10 PM THIS EVENING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE THREAT FOR SEVERE WEATHER WILL RETURN ON SUNDAY AFTERNOON AND
AGAIN ON MONDAY AFTERNOON AS THE WEATHER PATTERN REMAINS LARGELY
UNCHANGED.

.SPOTTER INFORMATION STATEMENT...

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