Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 192333
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
633 PM CDT TUE AUG 19 2014

.UPDATE...
ISSUED AT 635 PM CDT TUE AUG 19 2014

NO CHANGES NEEDED FOR THIS UPDATE.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 320 PM CDT TUE AUG 19 2014

MAIN FORECAST CHALLENGE WILL BE PCPN CHANCES AND HEAVY RAIN
THREAT. NAM LOOKS TO BE THE ODD MODEL OUT WITH MAIN SURFACE LOW
TOO FAR NORTH FOLLOWED BY GEM WITH FARTHER SOUTH GFS/ECMWF IN
PRETTY GOOD AGREEMENT AND WILL USE LATER FOR FORECAST.

FOR TONIGHT SURFACE AND MID LEVEL SHORT WAVE RIDGE TO SHIFT EAST
SETTING UP WEAK RETURN FLOW. EASTERN FA WILL BE CLOSEST TO SURFACE
RIDGE AXIS AND WILL HAVE THE BEST POTENTIAL FOR FOG AND WILL
INCLUDE IN FORECAST. TEMPERATURES CURRENTLY A FEW DEGREES WARMER
THAN YESTERDAY SO MINIMUMS SHOULD FOLLOW.

SOUTHWEST MID LEVEL FLOW GRADUALLY TAKES SHAPE LATE TONIGHT INTO
WEDNESDAY AS RIDGE SHIFTS EAST. SURFACE LOW PRESSURE ORGANIZES
ACROSS THE CENTRAL/NORTHERN HIGH PLAINS DURING THE DAY. MAIN LOW
WILL OVER CENTRAL HIGH PLAINS WITH DEVELOPING E-W WARM FRONT AND
THIS LIKELY TO BE THE FOCUS FOR CONVECTIVE DEVELOPMENT. AT PEAK
HEATING BOUNDARY DEPICTED BY MOST MODELS FROM E CENTRAL SD INTO S
MN WITH DEVELOPMENT ALONG AND NORTH OF BOUNDARY. SO AT THIS POINT
BEST POTENTIAL LOOKS TO BE ACROSS THE SOUTHERN FA. N-S ORIENTED
INVERTED TROUGH LOOKS TO BE MAINLY WEST OF THE FA SO LEFT LOWER
POPS GOING ACROSS THE DVL BASIN. TEMPERATURES WILL DEPEND ON CLOUD
COVER HOWEVER COLUMN WARM SO ANY BREAKS WILL BOOST TEMPERATURES.

AS INITIAL SHORT WAVE LIFTS NORTHEAST WEDNESDAY NIGHT T SHOULD
CONTINUE TO BECOME MORE WIDESPREAD. MODELS DIFFER SOMEWHAT ON HOW
FAR NORTH WARM FRONT WILL LIFT AND THIS WILL HAVE A BIG BEARING ON
WHERE HEAVIEST RAIN WILL FALL. GFS/ECMWF FOCUS HEAVIER RAIN
POTENTIAL FROM ND/SD/MN BORDER SOUTH AND EASTWARD WHILE GEM/NAM
FARTHER NORTH. SOUTHERN FA HAS SEEN RECENT HEAVY RAINFALL SO IF
SOUTHERN SOLUTION DOES PAN OUT MAY NEED SOME HEADLINES. WITH SPLIT
SOLUTIONS WILL HOLD OFF FOR NOW.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 320 PM CDT TUE AUG 19 2014

RAIN WILL GRADUALLY PUSH EAST DURING THE DAY THURSDAY. WILL LIKELY
SEE SOME DEGREE OF CLOUD COVER PERSISTING SO MAXIMUM TEMPERATURES
TO BE A FEW DEGREES COLDER.

FA SHOULD BE BETWEEN SYSTEMS THURSDAY NIGHT INTO PART OF THE DAY
FRIDAY FOR GENERALLY DRY CONDITIONS. TEMPERATURES WILL AGAIN HINGE
ON CLOUD COVER.

LONGWAVE PATTERN DEAMPLIFIES THIS PERIOD WITH LONGWAVE RIDGE/TROUGH
OVER THE EASTERN PACIFIC/WESTERN NORTH AMERICA AND PATTERN SHIFTS
EAST THIS PERIOD. GFS IS FAST WITH LEAD SHORT WAVE AT 84 HOURS
COMPARED TO THE OTHER MODELS. THEN THE GFS BECOMES SLOWER THAN THE
ECMWF TOWARD THE END OF THE PERIOD. GFS AND THE ECMWF HAVE TRENDED
FARTHER WEST/NORTHWEST WITH LAST COUPLE MODEL RUNS. WILL PREFER THE
ECMWF.

THREW OUT POPS FROM THE GFS. REDUCE POPS IN NORTHERN 2/3 OF FORECAST
AREA FOR FRI NIGHT. INCREASED POPS EAST AND DECREASED POPS
NORTHWEST/WEST ON SAT NIGHT/SUN. DECREASED POPS IN THE SOUTH AND
INCREASED POPS NORTH ON MON.

LITTLE CHANGE TO TEMPS...A DEGREE OR TWO HIGHER FOR SAT...A DEGREE
OR TWO LOWER FOR SUN...NO CHANGE THEREAFTER.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 635 PM CDT TUE AUG 19 2014

VFR CONDITIONS EXPECTED...WITH SOME PATCHY FOG POSSIBLE TONIGHT
MAINLY IN THE EAST. SOUTHERLY WINDS WILL SLOWLY INCREASE ON
WEDNESDAY...AND COULD GUST TO NEAR 20KT BY MID/LATE AFTERNOON.

&&

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

$$

UPDATE...DK
SHORT TERM...VOELKER
LONG TERM...HOPPES/VOELKER
AVIATION...DK





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