Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 012336
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
636 PM CDT SAT AUG 1 2015

.UPDATE...
ISSUED AT 629 PM CDT SAT AUG 1 2015

SEVERE THUNDERSTORM WATCH 460 HASD BEEN ISSUED FOR EXTREME
SOUTHEASTERN ND AND ADJACENT COUNTIES NORTHEASTERN SD AND WEST
CENTRAL MN UNTIL MIDNIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 325 PM CDT SAT AUG 1 2015

TWO SEPARATE SHORTWAVES WILL AFFECT THE REGION THIS
EVENING/OVERNIGHT.

THE FIRST WAVE WILL BRING A SEVERE THREAT TO A PORTION OF SE ND
AND WC MN. CURRENT SFC ANALYSIS INDICATES A WEAK SFC LOW ACROSS
SOUTH-CENTRAL NORTH DAKOTA...WITH A WARM FRONTAL FEATURE
EXTENDING TO THE SOUTHEAST. DEWPOINT VALUES ALONG THESE FEATURES
HAVE POOLED INTO THE MID-UPPER 60S...LEADING TO MLCAPE 3000-3500
J/KG. AS THIS SYSTEM EVOLVES AND PROPAGATES TOWARD THE
FA...ANTICIPATE THUNDERSTORM DEVELOPMENT ACROSS THE FAR SOUTHERN
FA. 0-6KM BULK SHEAR 35-40 KNTS COMBINED WITH THE STRONG
INSTABILITY WILL LEAD TO SEVERE STORMS...ALTHOUGH COVERAGE SHOULD
REMAIN ISOLATED GIVEN CONVECTIVE TEMPS NEAR 90F (SOME CAPPING
ISSUES). THIS ACTIVITY WILL MOVE OUT OF THE REGION BY EARLY
EVENING. DID ADD T+ (SEVERE STORMS POSSIBLE) ACROSS FAR SE ND
WHERE CONFIDENCE IS HIGHER IN THUNDER DEVELOPMENT (LOW LEVEL
CONVERGENCE WILL BE MAXIMIZED...AND THE HRRR HAS CONSISTENTLY
INDICATED DEVELOPMENT FROM RUN TO RUN).

NEXT UP WILL BE THE NORTHERN FA THIS EVENING INTO THE OVERNIGHT
HOURS...AS A STRONGER UPPER WAVE BRINGS A COLD FRONT THROUGH THE
REGION. THIS ACTIVITY WILL ENCOUNTER WEAK INSTABILITY (MUCAPE
500-1000 J/KG) BUT VERY STRONG DEEP LAYER SHEAR (60+
KNOTS)...ALONG WITH MID-LEVEL WINDS IN EXCESS OF 50 KNTS. THE 18Z
HRRR IS INDICATING A SMALL BOW ECHO WITH SFC WIND GUSTS 50-55
KNOTS 02Z-05Z. OF COURSE THAT IS JUST ONE POSSIBLE SOLUTION...BUT
IT DOES SPEAK TO THE POTENTIAL OF WHAT COULD OCCUR ACROSS THE
NORTHERN FA THIS EVENING AND OVERNIGHT. THIS FORCING MAY ALSO
INTERACT WITH INCREASING INSTABILITY FROM THE SOUTH AFTER
MIDNIGHT...WHICH MAY BE ENOUGH FOR A FEW STRONGER STORMS INTO THE
OVERNIGHT HOURS.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 325 PM CDT SAT AUG 1 2015

THIS PERIOD STARTS OFF WITH A BROAD UPPER LEVEL LOW OVER ONTARIO
AND COOL HIGH PRESSURE IN PLACE AT THE SURFACE OVER SASKATCHEWAN
AND THE DAKOTAS. THE WEATHER WILL BE DRY AND SLIGHTLY COOLER THAN
AVERAGE FOR THE START OF THE WEEK. HOWEVER...A WEAK UPPER LEVEL
WAVE WILL MOVE EAST IN THE WEAK UPPER FLOW...UNDERCUTTING A
WESTERN U.S. RIDGE BY MID WEEK. THE MODELS HAVE HAD A HARD TIME
WITH THIS SYSTEM. PREVIOUS RUNS HAD MORE INSTABILITY AND MUCH MORE
OF A PRECIPITATION SIGNAL AREA-WIDE. THE LATEST GFS HAS BEST
LIFT/INSTABILITY IN THE FAR SOUTH ON WEDNESDAY NIGHT.
SO...CONFIDENCE IS DECREASING IN WEDNESDAYS SYSTEM. ANOTHER WEAK
WAVE WILL AFFECT PRIMARILY THE SOUTH ON THURSDAY...BUT
AGAIN...THIS ONE HAS TRENDED SOUTHWARD. HOWEVER...FRIDAYS SYSTEM
LOOKS TO BE THE WAVE THAT HAS THE MOST AGREEMENT REGARDING TRACK
AND COULD BRING WIDESPREAD PRECIP TO THE AREA. WITH PLENTY OF
UNCERTAINTY ON THESE WAVES...TOO EARLY TO TALK ABOUT SEVERE
POTENTIAL. PRECIPITATION CHANCES EXIST INTO SATURDAY AS WELL AND
WILL DEPEND ON SPEED OF UPPER LOW. TEMPERATURES LOOK TO BE COOL
FOR MUCH OF THIS PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 629 PM CDT SAT AUG 1 2015

GENERALLY FAIR SKIES THROUGH THE EVENING WITH ISOLATED STRONG TO
SEVERE THUNDERSTORMS ALONG THE SOUTH DAKOTA BORDER COUNTIES...
INTO ADJACENT AREAS OF WEST CENTRAL MINNESOTA. THUNDERSTORMS
SHOULD EXIT THAT AREA BY 04Z.

LATER TONIGHT... A WEAK COLD FRONT WILL DROP FROM SOUTHERN SASK
AND MANITOBA ACROSS THE NORTHERN HALF OF THE FA... ALG AND NORTH
OF A CANDO TO GRAND FORKS AND BEMIDJI LINE... WITH SCATTERED
SHOWERS AND AN ISOLATED MVFR CIG AND VSBY IN STRONG THUNDERSTORMS
IN THE MIX. SCTATTERED SHOWERS SHOULD PERSIST INTO TEH MORNING
HOURS ACROSS NORTHERN MN.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...SEVERE THUNDERSTORM WATCH 460 UNTIL MIDNIGHT.
MN...SEVERE THUNDERSTORM WATCH 460 UNTIL MIDNIGHT
&&

$$

UPDATE...GUST
SHORT TERM...TG
LONG TERM...KNUTSVIG
AVIATION...GUST


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