Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 270536
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1236 AM CDT MON JUL 27 2015

.UPDATE...
ISSUED AT 1236 AM CDT MON JUL 27 2015

LATEST LOCAL RADAR SHOWS AN AREA OF SHOWERS AND SCATTERED
THUNDERSTORMS FROM EARLIER IN THE EVENING CURRENTLY LOCATED OVER
GRANT/SIOUX/EMMONS COUNTIES. MOVEMENT ON THIS AREA APPEARS TO BE
TAKING ON MORE OF A NORTHEAST TREND...AND THIS IS SOMEWHAT
SUPPORTED IN THE LATEST HRRR AND RAP13. THUS...HAVE COORDINATED
WITH ABERDEEN WFO TO CONTINUE MENTION OF SHOWERS/THUNDERSTORMS
SOUTH CENTRAL OVERNIGHT EXTENDING INTO THE SOUTHERN JAMES RIVER
VALLEY. REGIONALLY...THE NEXT AREA OF THUNDERSTORMS WOULD BE THE
NORTHWEST OVERNIGHT IN CLOSE PROXIMITY TO THE DEVELOPING WARM
FRONT/LOW LEVEL JET. THE NAM/HRRR/RAP13 SUGGESTS SHOWERS AND
THUNDERSTORMS GRAZING OUR NORTHWEST CORNER TOWARD 12Z MONDAY. REST
OF FORECAST IS ON TRACK.

UPDATE ISSUED AT 1039 PM CDT SUN JUL 26 2015

SEVERE THUNDERSTORM WATCH HAS EXPIRED. ONLY A SMALL AREA OF
THUNDERSTORMS REMAINS...OVER GRANT AND SIOUX COUNTIES. KEPT HIGHER
CHANCES OF PRECIPITATION THERE THROUGH MIDNIGHT CDT...WITH SLIGHT
CHANCES TO THE NORTHEAST ALONG THE EARLIER CONVECTION AXIS.

ATTENTION THEN TURNS TO LATER TONIGHT WITH POTENTIAL CONVECTION OVER
NORTHWESTERN NORTH DAKOTA.

UPDATE ISSUED AT 840 PM CDT SUN JUL 26 2015

QUICK UPDATE TO TAKE SEVERAL COUNTIES OUT OF THE WATCH. ALL
NORTHERN TIER COUNTIES ARE NOW OUT...AND TOOK OUT SOME WESTERN
COUNTIES. THOSE REMAINING IN THE WATCH UNTIL 10 PM CDT INCLUDE
MCLEAN...MERCER...OLIVER...MORTON...HETTINGER...GRANT.

CONVECTION HAS WEAKENED SIGNIFICANTLY NORTH...AND EXPECT SOUTHERN
END OF LINE TO DIMINISH GRADUALLY THIS EVENING. HAD TO ADD SOME
MENTION OF CHANCE OF SHOWERS AND THUNDERSTORMS EASTWARD INTO
SHERIDAN/WELLS/BURLEIGH/KIDDER...AS STORMS HOLDING TOGETHER. DO
NOT EXPECT SEVERE STORMS OUTSIDE THE WATCH AREA...EXCEPT PERHAPS FOR
ADAMS/SIOUX COUNTIES.

UPDATE ISSUED AT 648 PM CDT SUN JUL 26 2015

A LINE OF STRONG TO SEVERE STORMS CONTINUES FROM BOTTINEAU/ROLETTE
COUNTY SOUTHWESTWARD TO BOWMAN COUNTY. SEVERE THUNDERSTORM WATCH
CONTINUES FOR THIS AREA AND EAST TO PIERCE/ROLETTE TO
MORTON/GRANT...BUT WILL ALLOW THE WATCH TO EXPIRE FOR SOME OF THE
WESTERN COUNTIES...NAMELY BURKE...MOUNTRAIL...MCKENZIE AND BILLINGS
COUNTIES.

LINE OF STORMS IS MAINLY ALONG A SURFACE FRONTAL BOUNDARY...WHICH
HAS MOVED EASTWARD DURING THE LATE AFTERNOON AND EVENING.

ADJUSTED HOURLY TEMPS/WINDS TO ACCOUNT FOR LATEST OBSERVATIONS AND
TRENDS.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 209 PM CDT SUN JUL 26 2015

BLENDED THE CURRENT POPS WITH THE HRRR ENSEMBLE FOR THE REMAINDER
OF THE AFTERNOON AND EVENING. AS OF 2 PM CDT THUNDERSTORMS HAVE
INITIATED ALONG THE FRONTAL BOUNDARY IN NORTHWEST NORTH DAKOTA.
BUFKIT 12Z SOUNDINGS SHOW A CAP IN PLACE SUNDAY AFTERNOON BIS-JMS
SO USED THIS AS THE EASTWARD EXTENT FOR THE CONVECTION THIS
AFTERNOON AND EVENING. 20Z WATER VAPOR IMAGE SHOWS WEAK TROUGH
MOVING THROUGH NORTHEAST MONTANA WITH THE MAIN UPPER LOW COMING ON
SHORE ACROSS WASH/OR. AS THE FLOW ALOFT BECOMES PARALLEL WITH THE
COLD FRONT IT WILL ONLY MAKE IT THROUGH WEST CENTRAL NORTH DAKOTA
SUNDAY EVENING...THEN LIKELY RETREAT TO THE NORTHWEST AS
INCREASING LOW LEVEL SOUTHEAST FLOW BECOMES MORE PREDOMINANT LATE
TONIGHT IN RESPONSE TO THE UPPER LOW MOVING TO MONTANA BY MONDAY
MORNING. AS THIS HAPPENS THE FOCUS FOR THUNDERSTORMS TONIGHT WILL
DIMINISH CENTRAL AND RETURN TO THE NORTHWEST.

ON MONDAY MID LEVEL COOLING AND INCREASING MID LEVEL ADIABATIC
LAPSE RATES WILL CREATE IMPRESSIVE CAPE VALUES IN EXCESS OF 4000.
WITH COLD FRONTAL BOUNDARY SET TO HELP BREAK THE CAP SEVERE
THUNDERSTORMS ARE ANTICIPATED ACROSS THE NORTHWEST MONDAY MORNING
AND ALONG AND WEST OF HIGHWAY 83 BY AFTERNOON.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 209 PM CDT SUN JUL 26 2015

THE MAIN FOCUS FOR THE LONG TERM IS THE POTENTIAL FOR A SEVERE
WEATHER OUTBREAK TOMORROW EVENING.

AN UPPER LEVEL TROUGH WILL DIG INTO THE NORTHERN ROCKIES TOMORROW.
THIS WILL PROVIDE AMPLE UPPER LEVEL ASCENT ACROSS THE NORTHERN
PLAINS AHEAD OF THE TROUGH. ADDITIONALLY...A DEEP SURFACE LOW AND
COLD FRONT WILL DEVELOP ACROSS EASTERN MONTANA...WITH A WARM
FRONT DRAPED ACROSS THE INTERNATIONAL BOARDER. AFTERNOON HEATING
ACROSS A VERY WARM AND MOIST WARM SECTOR WILL LIKELY YIELD CAPE
VALUES GREATER THAN 3000 J/KG. AFTERNOON CAPING DUE TO AN
ELEVATED WARM LAYER WILL LIKELY INHIBIT CONVECTION FROM FORMING
ACROSS ALL BUT FAR WESTERN NORTH DAKOTA UNTIL THE EARLY EVENING
HOURS...WHEN MID LEVEL COOLING AND STRONGER FORCING ARRIVES VIA
THE UPPER LEVEL WAVE. INITIALLY...ISOLATED SUPERCELLS ARE
POSSIBLE...WITH VERY LARGE HAIL...DAMAGING WINDS AND A FEW
TORNADOES. ONCE THE COLD FRONT AND UPPER LEVEL WAVE BEGINS PUSHING
EASTWARD ACROSS THE STATE...A TRANSITION TO DAMAGING LINE SEGMENTS
(WITH VERY STRONG WINDS AND SOME HAIL) APPEARS LIKELY.

DURING THE DAY TUESDAY...A SECONDARY PRESSURE SURGE WILL PRODUCE
VERY STRONG WINDS ACROSS THE REGION. WITH PRESSURE RISES BETWEEN
15 AND 20 MB/6HOUR...AND A STRONG DOWNSLOPE COMPONENT...WIND GUSTS
AROUND 50 MPH ARE POSSIBLE. TEMPERATURES TUESDAY WILL BE
CONSIDERABLY COOLER WITH READINGS ON AVERAGE 20 TO 30 DEGREES
COOLER THAN MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1236 AM CDT MON JUL 27 2015

THERE IS SOME POTENTIAL FOR STRATUS CLOUDS/IFR CIGS TO AFFECT
KBIS/KJMS TOWARD 12Z MONDAY...HOWEVER WILL GIVE THIS SOME
ADDITIONAL TIME BEFORE GOING WITH A PREDOMINATE CLOUD GROUP. AN
AREA OF SHOWERS AND THUNDERSTORMS SOUTH OF KBIS/KJMS THROUGH 12Z
MONDAY COULD PRODUCE LOWER CLOUDS INTO THESE TERMINALS WITH A
SOUTH TO SOUTHEAST WIND. OTHERWISE...A SIGNIFICANT COLD FRONT
WILL SUPPORT THE DEVELOPMENT OF SEVERE THUNDERSTORMS FROM 21Z
MONDAY THROUGH THEN END OF THE TAF PERIOD. WILL CONTINUE WITH A
VCTS AND TRY TO BECOME MORE SPECIFIC WITH THE 12Z TAF ISSUANCE.

&&

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

$$

UPDATE...KS
SHORT TERM...WAA
LONG TERM...AJ
AVIATION...KS



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