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000
FXUS63 KFGF 181819
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
119 PM CDT SAT MAY 18 2013

.UPDATE...
ISSUED AT 107 PM CDT SAT MAY 18 2013

AREA OF RAIN CONTINUES TO LIFT SLOWLY NORTH AND IS NOW ALONG THE
CANADIAN BORDER. NO MODEL REALLY HINTED AT THIS MUCH FROM 00Z AND
12Z RUNS. REST OF AREA DRY SOUTH OF HIGHWAY 2. SOME CLEARING IN SE
ND WORKING NORTH A BIT...AND IN THIS CLEAR AREA TEMPS IN THE 77 TO
80 DEGREE RANGE FROM TENNEY-WAHPETON TO FARGO-VALLEY CITY. DEW PTS
RANGE FROM UPPER 50S TO MID 60S IN THIS AREA. IT IS THIS AREA
WHICH WILL SEE CAPES 1500-2000 J/KG LATE TODAY...AND COULD SEE
STORM DEVELOPMENT. 12Z SPC WRF SHOWS SOME DEVELOPMENT FAR-DTL 22Z-
00Z WHEREAS HRRR SHOWS IT MORE AXN-BRD REGION. UPDATED POPS TO
SHOW THIS INCREASE IN POPS IN THE FAR SOUTH-SOUTHEAST AFTER 22Z.
DISC WITH WFO DLH/MPX WILL HOLD OFF ANY FFA FOR NOW HAS HEAVIEST
CONVECTION EARLIER THIS MORNING-LAST NIGHT WAS AXN-STC-BRD REGION
JUST TO OUR SOUTH.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 326 AM CDT SAT MAY 18 2013

FORECAST CHALLENGE THROUGH THE SHORT TERM WILL CONTINUE TO BE PCPN
CHANCES AS WELL AS SEVERE STORM AND HEAVY RAIN POTENTIAL. MODELS
IN FAIR AGREEMENT WITH MAIN FEATURES HOWEVER SUBTLE DIFFERENCES
EXIST WITH SURFACE LOW/BOUNDARY POSITIONS TODAY.

ARC OF WEAKENING CONVECTION LIFTING NE THROUGH FA AT 30KTS WILL
CONTINUE TO PROPAGATE NE THROUGH THE MORNING AND INTO EARLY
AFTERNOON. WILL ATTEMPT TO ADJUST/TIME POPS ACCORDINGLY.

TEMPERATURES WILL BE TRICKY AND DEPENDENT ON DEGREE OF CLOUD COVER
AND HOW FAR NORTH WARM FRONT GETS. WITH WARM COLUMN ANY BREAKS
WILL REALLY BOOST TEMPERATURES.

LATER TODAY AND INTO TONIGHT. SURFACE INVERTED TROUGH TO SHARPEN
ACROSS FA PROVIDING GOOD SOURCE OF LOW LEVEL CONVERGENCE. TOUGH TO
DETERMINE ANY SPECIFIC SHORT WAVE HOWEVER REGION COMES UNDER
ENTRANCE REGION OF MODEST JET STREAK WHICH WILL AID IN UPPER
SUPPORT. MODELS DIFFER ON LOCATION OF SURFACE LOW WHICH WILL RIDE
NORTHWARD ALONG TROUGH AS WELL AS POSITION OF WARM FRONTAL
BOUNDARY. MODELS INDICATING GOOD SURFACE MOISTURE FLUX WITH 60
DEWPOINTS SPREADING NORTHWARD THROUGH MOST OF FA. PRECIPITABLE H2O
VALUES INCREASE TO AROUND 1.5 BY EVENING. GREATEST INSTABILITY AND
CAPE ACROSS SOUTH HALF OF FA AND LOOKS TO BE THE FAVORED LOCATION
FOR SEVERE POTENTIAL. SOME CAPPING MAY INITIALLY DELAY CONVECTIVE
INITIATION DURING THE AFTERNOON. HEAVY RAIN POTENTIAL THERE BUT WITH
DIFFERENCES IN SURFACE LOW POSITION TO ENHANCE LOW LEVEL
CONVERGENCE NOT AS CLEAR CUT.

INVERTED TROUGH TO DRIFT EAST SUNDAY WHICH WILL PUT HEAVIER RAIN
THREAT INTO MN. TEMPERATURES TO BE QUITE A BIT COOLER ON BACK SIDE
OF INVERTED TROUGH.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 326 AM CDT SAT MAY 18 2013

CUT OFF LOW TAKES OVER AND DRIFTS ACROSS E SD INTO S MN TO START WORK
WEEK FOR CONTINUED MODERATE RAIN POTENTIAL AND COOLER TEMPERATURES.

TUESDAY-FRIDAY...THE UPPER LOW WILL SLOWLY SHIFT EASTWARD FROM THE
CENTRAL/NORTHERN PLAINS INTO THE GREAT LAKES DURING THIS PERIOD. THE
00Z GFS/12Z ECMWF BEGIN TO SHIFT SHOWER ACTIVITY SOUTH AND EAST ON
WEDNESDAY...WITH THE GEM SLOWER IN ENDING THE PRECIP. WILL CONTINUE
TO MENTION POPS ACROSS THE SOUTHEAST THROUGH WEDNESDAY NIGHT. SFC
HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE AREA TOWARDS THE END
OF THE WEEK AS MID/UPPER LEVEL RIDGING DEVELOPS ACROSS THE PLAINS.
BELOW NORMAL TEMPS WILL MODERATE BACK TO NEAR NORMAL BY LATE NEXT
WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 107 PM CDT SAT MAY 18 2013

ACROSS NERN ND AND NRWN MN...AREAS OF IFR TO LIFR CIGS AND VSBYS
ALG AND NORTH OF U.S. HWY 2 WILL SLOWLY LIFT AND SHIFT NORTHWARD
THIS AFTERNOON...WITH SCT MVFR CIGS LIKELY TO PERSIST INTO THE
EVENING. SCT TSTMS ARE EXPECTED TO DEVELOP FROM LATE AFTERNOON
INTO THE EARLY EVENING...BECOMING MORE NUMEROUS INTO THE LATE
EVENING. ACROSS SERN ND INTO WCNTRL MN...AREAS OF LIFR TO IFR CIGS
AND VSBYS ALG AND EAST OF AN AXN-BJI LINE WILL SLOWLY LIFT AND
SHIFT NORTHEASTWARD THROUGH THIS AFTERNOON...WITH SCT MVFR CIGS
LIKELY TO PERSIST INTO THE EVENING. OTHERWISE...FAIR SKIES OVER
THE SOUTHERN RRV WILL ALLOW FOR INCREASED SFC HEATING AND THE
DEVELOPMENT OF SCT TSTMS /WITH ISOLD LARGE HAIL/ FROM MID
AFTERNOON INTO THE EARLY EVENING...BECOMING MORE NUMEROUS INTO
MIDNIGHT.

&&

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

$$

UPDATE...RIDDLE
SHORT TERM...VOELKER
LONG TERM...MAKOWSKI/VOELKER
AVIATION...GUST