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000
FXUS63 KBIS 131803
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
103 PM CDT THU JUN 13 2013

.UPDATE...
ISSUED AT 103 PM CDT THU JUN 13 2013

NO MAJOR CHANGES WERE MADE TO THE ONGOING FORECAST. WINDS ACROSS
SOUTHWESTERN NORTH DAKOTA CONTINUE TO BE NEAR WIND ADVISORY
CRITERIA. HOWEVER...THINK ANY IMPACTS WILL BE MINIMAL.
THEREFORE...WILL CONTINUE TO HOLD OFF ON ISSUING AN ADVISORY FOR
BOWMAN AND SLOPE COUNTIES.

OTHERWISE...THE REMAINING WEATHER ELEMENTS ARE IN GOOD SHAPE. THE
UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT.

UPDATE ISSUED AT 1006 AM CDT THU JUN 13 2013

THE MAIN FORECAST CHALLENGE FOR TODAY WILL BE JUST HOW HIGH THE
WINDS WILL GET ACROSS EXTREME SOUTHWESTERN NORTH DAKOTA (SLOPE AND
BOWMAN COUNTIES). ALTHOUGH WIND SPEEDS ALOFT (AND SUBSEQUENT WIND
GUSTS) ARE NOWHERE NEAR ADVISORY CRITERIA...GRADIENT FLOW
GENERATED BY LOW PRESSURE OVER SOUTH CENTRAL MONTANA AND HIGH
PRESSURE OVER EASTERN NORTH DAKOTA COULD GENERATE SUSTAINED WINDS
UP TO 26 KNOTS (30 MPH) OVER SOUTHWESTERN NORTH DAKOTA TODAY. THE
SUSTAINED WIND AT BAKER WAS 27 KNOTS AND 28 KNOTS AT BUFFALO AT
15Z. DUE TO MARGINAL TO LOW-END WIND ADVISORY CONDITIONS...WILL
FOREGO A WIND ADVISORY FOR NOW. WILL CONTINUE TO MONITOR TRENDS
AND MAY NEED TO RE-EVALUATE FOR THE 1 PM CDT UPDATE.

THE REMAINING FORECAST ELEMENTS ARE IN GOOD SHAPE. THE UPDATED
PRODUCTS HAVE BEEN SENT.

UPDATE ISSUED AT 642 AM CDT THU JUN 13 2013

LOW PRESSURE WILL MOVE FROM CENTRAL INTO EASTERN MONTANA TODAY
BRINGING AND INCREASING SOUTH TO SOUTHEAST FLOW TO THE FORECAST
AREA. CURRENTLY HIGH PRESSURE OVER THE AREA WITH LIGHT WINDS OVER
CENTRAL AND EASTERN NORTH DAKOTA. SOME PATCHY FOG NOTED ALONG THE
MISSOURI RIVER VALLEY. CURRENTLY A MENTION OF FOG THROUGH 12 UTC.
ONLY UPDATES WERE MINOR ADJUSTMENTS TO SKY COVER AND POPULATING
LATEST HOURLY OBSERVATIONS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU JUN 13 2013

CURRENTLY...AN UPPER LEVEL RIDGE AXIS EXTENDED FROM THE SOUTHERN
PLAINS NORTHWARD THROUGH THE DAKOTAS AND INTO SOUTH CENTRAL CANADA.
MEANWHILE A LARGE-SCALE UPPER LEVEL TROUGH AXIS WAS OVER THE WEST
COAST OF NORTH AMERICA...WITH MANY UPPER LEVEL ENERGY IMPULSES
MOVING FROM THE BASE OF THE TROUGH NORTHEASTWARD ACROSS THE ROCKIES
AND INTO WYOMING/MONTANA/ALBERTA/SASKATCHEWAN. THESE IMPULSES WERE
ASSOCIATED WITH THE CONVECTION FROM WEDNESDAY THAT DEVELOPED OVER
THE EASTERN ROCKIES AND INTO THE FRONT RANGE - WITH LINGERING
ONGOING ISOLATED CELLS OVER MONTANA EARLY THIS MORNING. AT THE
SURFACE...A SURFACE HIGH PRESSURE RIDGE AXIS EXTENDED FROM MANITOBA
TO THE CENTRAL DAKOTAS...WHILE LOW PRESSURE CONTINUED TO DEVELOP IN
THE LEE OF THE ROCKIES OVER MONTANA AND WYOMING.

TODAY...THE UPPER LEVEL RIDGE AXIS IS FORECAST TO MOVE EASTWARD
SLOWLY. AS IT DOES...A THERMAL RIDGE CONTINUES TO BUILD OVER THE
WESTERN DAKOTAS WITH H700 TEMPS OF +10C TO +12C. THIS WILL BE WARM
ENOUGH TO CAP OR INHIBIT DAYTIME SURFACE-BASED CONVECTION. AT THE
SURFACE...THE LEE-SIDE LOW IS FORECAST TO DEVELOP/MOVE EASTWARD AND
APPROACH THE WESTERN DAKOTAS THIS EVENING...ENTERING WESTERN NORTH
DAKOTA AFTER MIDNIGHT. LOOKING AT HIGHS TODAY IN THE MID TO UPPER
70S.

TONIGHT AS THE SURFACE LOW/TROUGH MOVES INTO WESTERN NORTH
DAKOTA...AND THE UPPER LEVEL RIDGE MOVES INTO THE RED RIVER VALLEY
AND INTO MINNESOTA...THE WESTERN ND THERMAL CAP WILL BEGIN TO ERODE
AND UPPER LEVEL IMPULSES MOVING THROUGH THE SOUTHWEST FLOW ALOFT
WILL SUPPORT CONVECTION IN THE FAR WEST BY AROUND MIDNIGHT. THIS
CONVECTION IS EXPECTED TO SPREAD EASTWARD INTO CENTRAL NORTH DAKOTA
OVERNIGHT.

ELEVATED CAPE VALUES OF 1000-2000 ARE FORECAST ALONG THE SURFACE
TROUGH WITH A POTENT SOUTHERLY LOW LEVEL JET THAT STRENGTHENS
TONIGHT. ALL THE INGREDIENTS FOR STRONG TO SEVERE THUNDERSTORMS WILL
BE IN PLACE WITH PLENTY OF INSTABILITY WITH INCREASING CAPE AND
SHEAR WITH 1KM MIXED LAYER BULK SHEAR VALUES OF 35-70 KNOTS.

PARTLY TO MOSTLY SUNNY TODAY WITH HIGHS IN THE MID TO UPPER 70S.
THEN INCREASING CLOUDS TONIGHT. SLIGHT CHANCE OF THUNDERSTORMS IN
THE FAR WEST THIS EVENING...THEN THUNDERSTORMS AFTER MIDNIGHT FAR
WEST SPREADING INTO CENTRAL NORTH DAKOTA LATE.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU JUN 13 2013

MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL BE THUNDERSTORM
CHANCES FRIDAY AND FRIDAY EVENING. MODELS ARE SIMILAR IN BRINGING
CONVECTION FIRING IN EASTERN MONTANA LATE TONIGHT...INTO WESTERN
NORTH DAKOTA FRIDAY MORNING...AND TRACKING IT EAST ACROSS THE CWA
DURING THE DAY. FRIDAY AFTERNOON AS THE UPPER LOW LIFTS NORTHEAST
INTO SASKATCHEWAN A STRONG UPPER LEVEL JET SWINGS FROM EASTERN
MONTANA INTO WESTERN NORTH DAKOTA. MODEL CONSENSUS PUTS THE SURFACE
BOUNDARY OVER CENTRAL NORTH DAKOTA WITH VERY WARM MOIST SOUTHERLY
FLOW BUT CAPPED ENVIRONMENT MAINLY ALONG AND EAST OF THE HIGHWAY 83
CORRIDOR. IF WE GET SOME CLEARING AND DESTABILIZATION AHEAD OF THE
FRONT WE COULD SEE A WINDOW OF OPPORTUNITY FRIDAY AFTERNOON AND
EARLY EVENING WHERE SUFFICIENT DEEP LAYER SHEAR COMBINED WITH RAPID
DESTABILIZATION WITH THE APPROACHING UPPER LEVEL IMPULSE WOULD
RESULT IN THE DEVELOPMENT OF STRONG TO SEVERE THUNDERSTORMS. THIS
WINDOW WILL QUICKLY CLOSE FRIDAY EVENING AS DRY AIR ALOFT AND A DRY
NORTHWEST SURFACE FLOW BEHIND THE FRONTAL BOUNDARY WILL ACT TO
INHIBIT CONVECTION. ANY CONVECTION THAT WOULD DEVELOP SHOULD BE EAST
OF THE FORECAST AREA BY MID EVENING FRIDAY.

SATURDAY APPEARS TO BE DRY AND BREEZY WITH THE UPPER LOW REMAINING
TO OUR NORTH. ON SUNDAY THE LOW DROPS SOUTHEAST INTO NORTHERN
MINNESOTA. THE COLD AIR ASSOCIATED WITH THE LOW SHOULD BE SUFFICIENT
TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS OVER THE NORTHERN AND
EASTERN PORTIONS OF THE FORECAST AREA.

UPPER LEVEL RIDGING BUILDS OVER THE AREA EARLY NEXT WEEK BRINGING A
BREAK IN THE THUNDERSTORM ACTIVITY MONDAY AND TUESDAY. ANOTHER UPPER
LEVEL LOW TRACKING ACROSS THE PACIFIC NORTHWEST WILL BRING A SMALL
CHANCE OF THUNDERSTORMS BY TUESDAY NIGHT AND WEDNESDAY...WITH BETTER
CHANCES EXPECTED JUST BEYOND THE EXTENDED PERIOD.

TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO BE SEASONABLE WITH
HIGHS MAINLY IN THE 70S AND LOWS IN THE 50S THROUGH MONDAY. THE
BUILDING UPPER LEVEL RIDGE OVER THE AREA NEXT WEEK SHOULD RESULT IN
TEMPERATURES WARMING INTO THE 80S ON TUESDAY AND WEDNESDAY WITH LOWS
PUSHING CLOSER TO THE 60S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 103 PM CDT THU JUN 13 2013

VFR CONDITIONS WILL PREVAIL OVER WESTERN AND CENTRAL
NORTH DAKOTA THIS AFTERNOON AND EVENING. THUNDERSTORMS AND
ASSOCIATED MVFR/IFR CONDITIONS WILL LIKELY IMPACT NORTHWESTERN NORTH
DAKOTA (KISN) AROUND MIDNIGHT TONIGHT. THIS ACTIVITY WILL SLOWLY
MOVE EAST FRIDAY MORNING AND IMPACT KDIK-KMOT-KBIS-KJMS. THERE IS
DIFFICULTY IN PINPOINTING THE TIMING OF STORMS. THEREFORE...UTILIZED
VCTS IN THE TAFS FOR THE INCREASING THUNDERSTORM PROBABILITIES
TOWARDS THE END OF THE TAF PERIOD.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

UPDATE...TM
SHORT TERM...JV
LONG TERM...TWH
AVIATION...TM