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000
FXUS63 KFGF 161751
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1251 PM CDT THU MAY 16 2013

.UPDATE...
ISSUED AT 1250 PM CDT THU MAY 16 2013

NO CHANGES PLANNED FOR THIS UPDATE...WILL CONTINUE TO WATCH THE
EASTWARD PROGRESSION OF SHOWERS. WE WILL DECREASE RH VALUES IN THE
EAST WITH DRY AIR REMAINING HERE THROUGH MUCH OF THE
AFTERNOON...AND ISSUE AN UPDATED FWF.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 340 AM CDT THU MAY 16 2013

FORECAST CHALLENGES THROUGH THE SHORT TERM WILL BE PCPN CHANCES
AND TEMPERATURES. MODELS IN REASONABLE AGREEMENT WITH FEATURES AND
TRENDS ALTHOUGH THEY HAVE ALL INITIALIZED TO MOIST WITH SURFACE
DEWPOINTS AND GFS QPF OVERDONE TO OUR WEST.

FOR TODAY SHORTWAVE IN CO WILL PROPAGATE SLOWLY NE NEXT 24 HOURS.
AS IT DOES SURFACE LOW PRESSURE WILL ORGANIZE OVER SE MT WITH E-W
BOUNDARY ALONG ND/SD BORDER. WITH MOIST AXIS FROM THE CENTRAL
PLAINS NW INTO THE WESTERN DAKOTAS FEEL BEST PCPN POTENTIAL WILL
BE TO OUR WEST. WITH EASTERLY FLOW OVER FA NOT SURE HOW FAR EAST
PCPN WILL HOLD TOGETHER. INHERITED SOME LOW POPS ACROSS THE
WESTERN FA AND WILL MAINTAIN. AS FOR TEMPERATURES COLUMN A LITTLE
COOLER AND WILL SEE A GRADUAL INCREASE IN CLOUDS AHEAD OF WAVE SO
TEMPERATURES WILL BE A FEW DEGREES COOLER. SLIGHTLY COOLER
TEMPERATURES AND RELATIVELY LIGHT EASTERLY FLOW SHOULD EASE FIRE
WEATHER CONCERNS.

WAVE WILL CONTINUE TO LIFT NE TONIGHT BUT LOOKS TO WEAKEN AS IT
DOES. SURFACE FEATURES/FORCING ALSO WEAKENS AS MAIN BOUNDARY SETS
UP ACROSS SD/S MN. EXPECTED T COMPLEX ALONG THIS BOUNDARY MAY ROB
SOME OF THE DEEPER MOISTURE LATER TONIGHT. GENERAL MODEL CONSENSUS
HAS BAND OF WEAKER PCPN LIFTING THROUGH DVL BASIN WITH MAIN ACTION
TO OUR SOUTH. JUST HOW FAR NORTH SD BOUNDARY SETS UP WILL
DETERMINE ANY THREAT ACROSS OUR FAR SOUTHERN FA BUT AT THIS POINT
LOOKS TO REMAIN SOUTH OF FA. IN OUR AREA INSTABILITY VERY LIMITED
SO WILL MAINTAIN SHRA VS T.

MAY SEE SOME LINGERING PCPN FRIDAY AM ACROSS FAR NORTH AND SOUTH
OTHERWISE BRUNT OF DAY LOOKING MORE LIKE IT WILL BE RAIN FREE. DEGREE
OF CLOUD COVER WILL DETERMINE TEMPERATURES SO WILL MAINTAIN
CONTINUITY. ADJUSTED POPS WITH THIS THINKING.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 AM CDT THU MAY 16 2013

MODELS BEGIN TO DIFFER ON SOLUTIONS ON HOW FAR NORTH WARM FRONT
WILL LIFT LATE FRIDAY NIGHT GFS FARTHEST SOUTH AND ECMWF FARTHEST
NORTH...ALONG THE ND/SD BORDER. AS A RESULT HELD PRETTY CLOSE TO
INHERITED POPS. WARM FRONT LIFTS INTO FA SATURDAY ALONG WITH
INCREASING INSTABILITY FOR BETTER POTENTIAL FOR T. CLOUD COVER
WILL DETERMINE TEMPERATURES BUT WITH WARMING COLUMN ANY BREAKS
COULD LIFT TEMPERATURES. AT THIS POINT THINK THERE MAY BE PLENTY
OF CONVECTIVE DEBRIS CLOUD COVER SO DID NOT RAISE TEMPERATURES
SIGNIFICANTLY.

BEST T POTENTIAL WILL BE LATE SATURDAY AFTERNOON INTO THE EVENING
AS SURFACE LOW PROPAGATES TO NE SD/SD ND BORDER AREA AND NE
EXTENDING BOUNDARY. BASED ON CONVECTIVE PARAMETERS SEVERE STORMS
CERTAINLY A POSSIBILITY.

WITH MOIST SOUTHWEST FLOW ALOFT FIRMLY IN PLACE ACROSS THE NORTHERN
PLAINS ON SUNDAY...THE MAIN QUESTION WILL BE WHERE DOES THE CLOSED
LOW DEVELOP WITHIN THE OVERALL LONG WAVE TROUGH EARLY NEXT WEEK. BY
12 UTC MONDAY...THE GFS PLACES THE CLOSED LOW NEAR BISMARCK...
WHEREAS THE ECMWF IS NEAR SIOUX FALLS SD. THE ECMWF/S MORE SOUTH AND
EAST POSITION RELATIVE TO THE GFS CONTINUES TO SOME EXTENT THROUGH
TUESDAY/WEDNESDAY. THIS PLACES THE FORECAST AREA IN A SLOW-MOVING
WRAP AROUND PRECIPITATION BAND FOR MULTIPLE DAYS. THE GFS/S MORE
WESTERLY POSITION...HOWEVER ALLOWS FOR PROLONGED GREATER INSTABILITY
ACROSS THE FORECAST AREA AND THE THREAT FOR MORE NUMEROUS TSTORMS.
IT ALSO SHOWS A MORE PRONOUNCED DRY SLOT MONDAY NIGHT INTO TUESDAY.
AT THIS TIME...PREFER THE ECMWF SOLUTION...WHICH HAS SUPPORT FROM
THE LATEST GEM. DESPITE MODEL DIFFERENCES...LOOK FOR PERIODS OF
SHOWERS AND THUNDERSTORMS SUNDAY THROUGH TUESDAY...AFTER WHICH THERE
SHOULD BE A SLOW DRYING TREND. STILL EARLY...BUT WITH PRECIPITABLE
WATER VALUES UP TO 1.5 INCHES...THERE IS A REAL POSSIBILITY FOR A FEW
INCHES (1-3 INCHES) OF ACCUMULATION BY EARLY NEXT WEEK. WITH CLOUD
COVER AND RAIN...TEMPERATURES NEXT WEEK WILL BE IN THE UPPER 50S AND
60S FOR DAYTIME HIGHS AND THE 40S FOR NIGHTTIME
LOWS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1250 PM CDT THU MAY 16 2013

MID LEVEL CLOUD DECK VALLEY WEST WILL ENCROACH UPON KTVF-KBJI THIS
AFTERNOON. INCLUDED TEMPO FOR -SHRA KDVL LATER AFTN WHICH COULD
AFFECT VALLEY BEYOND INITIAL 6 HR WINDOW AND WILL AWAIT FURTHER
EVALUATION. PERSISTENT EAST WIND AROUND 10 KTS LIKELY SITE-WIDE THROUGH
FRI.

&&

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

$$

UPDATE...DK
SHORT TERM...VOELKER
LONG TERM...ROGERS
AVIATION...WJB