Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 271445
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
945 AM CDT SAT JUN 27 2015

.UPDATE...
ISSUED AT 945 AM CDT SAT JUN 27 2015

THE MAIN CHALLENGE WILL BE SEVERE WEATHER THIS AFTERNOON/EVENING.
THINGS ARE LOOKING FAIRLY PRIMED FOR A FAIRLY WIDESPREAD SEVERE
EVENT STARTING BY 2 PM IN THE NORTH THEN SPREADING SOUTH AND EAST.
THE NAM IS PROGGING CAPES AROUND 3000 J/KG AND THERE WILL BE
PLENTY OF DEEP LAYERED SHEAR AND STEEP LAPSE RATES. THE LOW LEVEL
FLOW IS FAIRLY WEAK...BUT THERE ARE CURVED HODOGRAPHS SO
SUPERCELLS SHOULD BE THE INITIAL STORM MODE. THERE WILL BE
POTENTIALLY VERY LARGE HAIL...DAMAGING WINDS AND ISOLATED
TORNADOES. IF DEWPOINTS CAN POOL IN THE MID/UPPER 60S THEN THE
TORNADO THREAT WILL INCREASE. WE HAVE INCREASED POPS TO LIKELY IN
THE NORTH THIS AFTERNOON AND WILL MENTION SEVERE ALL AREAS AFTER 3
PM THROUGH 10 PM.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 318 AM CDT SAT JUN 27 2015

MAIN FOCUS IS SEVERE THREAT LATER TODAY. VARIOUS SHORT RANGE
SPC/NSSL/NCAR WRF MODELS SHOW CONVECTIVE DEVELOPMENT EARLY AFTN IN
THE LANGDON-DEVILS LAKE AREA INCREASING AS IT MOVES SOUTHEAST INTO
THE RRV LATE AFTERNOON...THEN INTO SRN VALLEY AND WCNTRL MN EARLY
THIS EVENING. STRONG SHORT WAVE NOTED UPSTREAM MOVING SOUTHEAST
THRU CNTRL SASK AND THIS SHORT WAVE TO MOVE INTO NW MN THIS
EVENING. OUT AHEAD OF IT AIRMASS WILL DESTABILIZE AS TEMPS WARM
INTO THE LOW-MID 80S AND DEW PTS CLIMB A BIT HIGHER INTO LOWER-MID
60S. NAM A BIT TOO AGGRESSIVE WITH DEW PTS AND THUS ITS HIGHER
(4000 J/KG) CAPE IN THE RRV LATE TODAY. BUT EVEN NCAR ENSEMBLE WRF
SHOW MEAN SURFACE BASED CAPES NR 3000 J/KG HALLOCK-GRAND FORKS
REGION AT 00Z. HODOGRAPH SHOWS SUFFICIENT TURNING OF WINDS WITH
HEIGHT AND WITH SFC LOW PROGGED TO BE SOMEWHERE IN THE NRN VALLEY
SOME CONCERN THAT ISOLATED TORNADOES WILL OCCUR IN THE NRN RRV
LATE THIS AFTN. SYSTEM IS PROGRESSIVE AND WILL CLEAR OUT OF THE
FCST AREA OVERNIGHT. LIKELY ANY SEVERE THREAT OVER BY 03-04Z.
DRIER BUT STILL WARM AIRMASS TO MOVE IN SUNDAY...THOUGH WITH
COOLER AIR ALOFT OVER NORTH CENTRAL MN WILL KEEP ISOLD TSTM
MENTION SUN AFTN.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 318 AM CDT SAT JUN 27 2015

HIGH PRESSURE OVER AREA SUN NIGHT INTO MONDAY. KEPT SOME LOW POPS
MON AFTN IN FAR EASTERN FCST AREA AS ENOUGH COOL AIR ALOFT AND SFC
HEATING FOR A RISK OF A STORM. VERY WARM ON MONDAY WITH TEMPS MID
TO UPPER 80S IN ERN ND/RRV.

TUESDAY-FRIDAY...MODELS CONTINUE TO SHOW NORTHWEST FLOW ALOFT ACROSS
THE REGION...WITH MAINLY DRY CONDITIONS AT THE START OF THE PERIOD.
THUNDER CHANCES WILL INCREASE TOWARD THE WEDNESDAY NIGHT-THURSDAY
TIME FRAME AS A SYSTEM CROSSES THE AREA. OTHERWISE...TEMPERATURES
WILL CONTINUE TO BE NEAR NORMAL VALUES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 656 AM CDT SAT JUN 27 2015

MAIN ISSUE IS TIMING OF TSTMS TODAY. USING VERY SHORT RANGE MODELS
INDICATED TEMPO GROUP 3-4 HOUR PERIOD WITH THE BEST CHC FOR STORMS
AT THE GIVEN TAF SITES. OUTSIDE OF THAT EXPECT AN INCREASING
SOUTH-SOUTHWEST WIND TODAY AHD OF THE FRONT WITH SOME GUSTS ABV 20
KTS...TURNING WEST TO NORTHWEST TONIGHT AND DIMINISHING. VFR CLOUD
BASES FCST BUT BRIEF MVFR CIG AND IFR/MVFR VSBYS IN RAIN POSSIBLE
WITH ANY STORM.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...DK
SHORT TERM...RIDDLE
LONG TERM...HOPKINS/RIDDLE
AVIATION...RIDDLE


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