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000
FXUS63 KBIS 132007
AFDBIS

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

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 307 PM CDT THU JUN 13 2013

THE MAIN FORECAST CONCERN FOR THE PERIOD WILL BE THE CHANCES FOR
SEVERE CONVECTION WEST OF HIGHWAY 85 THIS EVENING AND AGAIN ALONG
AND EAST OF HIGHWAY 83 FRIDAY AFTERNOON.

THIS AFTERNOON...SPC HAS PLACED MOST OF EASTERN MONTANA IN A SEVERE
THUNDERSTORM WATCH GIVEN THE INCREASING CAPE AND DEEP LAYER SHEAR.
ANY ACTIVITY THAT DEVELOPS OVER MONTANA WILL LIKELY MOVE NORTHEAST
ALONG THE 850MB-300MB MEAN WIND VECTOR. THIS COULD ALLOW FOR SOME
SEVERE STORMS THAT HAVE ALREADY DEVELOPED TO CROSS THE BORDER INTO
THE EXTREME WESTERN COUNTIES OF NORTH DAKOTA...PRIMARILY BETWEEN
00Z-06Z TONIGHT.

OTHERWISE...AN UPPER LOW IS PROGGED TO CONTINUE TO PUSH EAST ACROSS
THE NORTHERN PLAINS TONIGHT. ITS ATTENDANT SURFACE BOUNDARY IS
PROGGED TO ENTER WESTERN NORTH DAKOTA AROUND 12Z FRIDAY. ALONG WITH
IT WILL BE INCREASING CHANCES FOR THUNDERSTORMS ALONG AND WEST OF
HIGHWAY 85. HOWEVER...CAPE VALUES SHOULD BE DECREASING AFTER
MIDNIGHT SO THEREFORE THINK THE SEVERE THREAT WILL BE LOW.

FOR FRIDAY...THE UPPER LOW AND ITS SURFACE BOUNDARY ARE PROGGED TO
PUSH ACROSS WESTERN NORTH DAKOTA FRIDAY MORNING...AND EAST OF
HIGHWAY 83 FRIDAY AFTERNOON. GIVEN THE TIMING AND POSITION OF THE
UPPER LEVEL/SURFACE BOUNDARY...THINK SEVERE WEATHER HAS THE
POTENTIAL TO DEVELOP PRIMARILY ALONG AND EAST OF HIGHWAY
83...CONSISTENT WITH THE DAY 2 SLIGHT RISK BY SPC. THE ONLY FLY IN
THE OINTMENT IS IF WE REMAIN CAPPED THROUGH THE DAY. HOWEVER...THINK
THE UPPER LEVEL FORCING SHOULD SUFFICE TO ERODE THE MID-LEVEL
CAPPING. AS A RESULT...INTRODUCED THE CHANCES FOR SEVERE
THUNDERSTORMS ALONG AND EAST OF HIGHWAY 83 IN THE FORECAST. LARGE
HAIL AND DAMAGING WINDS WOULD BE THE BIGGEST THREATS.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 307 PM CDT THU JUN 13 2013

NO SIGNIFICANT WEATHER TO HIGHLIGHT THE EXTENDED WITH SLIGHTLY
BELOW NORMAL TEMPERATURES TO BEGIN THE PERIOD WITH NEAR
CLIMATOLOGICAL FORECAST TEMPERATURES AND PRECIPITATION CHANCES
EARLY TO MID NEXT WEEK.

OVERALL...THE 12 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT AND
UTILIZED A BLEND FOR MOST FIELDS. A BREEZY...BUT DRY SATURDAY IS
FORECAST IN THE DRY SLOT OF THE UPPER LEVEL LOW ACROSS
SASKATCHEWAN. AS THIS LOW FILLS AND PROPAGATES SOUTHEAST THROUGH
SUNDAY...THERE IS A CHANCE FOR ISOLATED TO SCATTERED DIURNAL SHOWERS
AND THUNDERSTORMS ACROSS NORTHERN NORTH DAKOTA AND THE JAMES RIVER
VALLEY WITH THE COLD CORE ALOFT. THEREAFTER...UPPER LEVEL RIDGING
BUILDS MONDAY THROUGH WEDNESDAY...WITH THE NEXT BEST CHANCE FOR
THUNDERSTORMS BEING POTENTIALLY THURSDAY WITH THE NEXT SIGNIFICANT
UPPER LEVEL WAVE. THAT SAID...TIMING OF THIS WAVE HAS BEEN
INCONSISTENT OVER THE PAST FEW RUNS AMONGST THE GUIDANCE.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 307 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.

&&

$$

SHORT TERM...TM
LONG TERM...AYD
AVIATION...TM