Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 170444
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1144 PM CDT SAT AUG 16 2014

.UPDATE...
ISSUED AT 1143 PM CDT SAT AUG 16 2014

STILL WATCHING THE AREA OF STEADIER RAIN AROUND THE KFFM AREA.
SEEMS LIKE THE WESTERN EDGE BACK AROUND WAHPETON IN ND IS SLOWLY
MOVING EAST BUT THE AREA NORTH OF KFFM IS NOT MOVING. THEREFORE
THINK THAT THE STEADY RAIN JUST NORTH AND NE OF KFFM HAS A
POTENTIAL FOR SOME FLASH FLOODING. DUAL POL AND LEGACY STORM TOTAL
PCPN MAPS ARE SHOWING A BULLSEYE AROUND THE MAPLEWOOD STATE PARK.
THIS AREA COULD SEE ANOTHER COUPLE OF HOURS OF STEADY RAIN SO WILL
GO WITH A FLASH FLOOD WARNING FOR THEM. SOME FOG FORMING ON THE
BACK EDGE OF THE CLOUDS OVER CENTRAL ND SO THINK AS THIS
PROGRESSES TO THE EAST FOG IS POSSIBLE INTO EASTERN ND.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 301 PM CDT SAT AUG 16 2014

VERY INTERESTING FORECAST AS SLOW MOVING WEATHER SYSTEM
APPROACHES THE RED RIVER VALLEY AND LAKES REGION. FOR TONIGHT THE
MAIN CHALLENGE IS HOW TO HANDLE THE UPPER LOW/CONVECTIVE COMPLEX
THAT HAS PRODUCED SIGNIFICANT RAINS TO OUR WEST. EXPECT THIS
SYSTEM TO CONTINUE ITS EASTWARD TREK AT 10KTS - 15KTS IN SPLIT
LARGE SCALE FLOW. WITH VERY HIGH PWATS AND MODEST INSTABILITY
ISOLATED HEAVY RAINS LIKELY. VARIOUS HIRES MODELS WEAKEN THE
COMPLEX AS IT MOVES INTO THE FGF CWFA EARLY...THEN SOME SHOW RE-
INTENSIFICATION AS THE SYSTEM INTERACTS WITH BOUNDARY MOVING
SOUTHWEST. HAVE FOLLOWED THE MODEL TRENDS WITH HIGHEST POPS AND
HEAVIEST QPF OVER THE SOUTHWEST CWFA.

SUNDAY FORECAST IS ALSO PROBLEMATIC AS THE SYSTEM TO THE WEST IS
EXPECTED TO MOVE ACROSS THE FGF CWFA. CURRENT THINKING IS THE
SHEARING THAT IS SHOWN IN THE MODELS AND APPARENT IN W/V IMAGERY
WILL ALLOW FOR LESS CONCENTRATION OF CONVECTION. WHILE THE SYSTEM
MAY ACCELERATE SOMEWHAT...IT WILL STILL MOVE FAIRLY SLOWLY. THE
GFS/ECMWF AND ESPECIALLY GEM-NH SHOW SIGNIFICANT QPF MAINLY OVER
THE WEST AND SOUTH FA. HAVE FOLLOWED A BLEND OF THE HPC/GFS/GEM
FOR RAINFALL TONIGHT INTO SUNDAY. ECMWF/GFS/GEM SHOW GREATEST
INSTABILITY AND 700 MB COOLING ALONG AND WEST OF VALLEY IN THE 18Z
SUN - 00Z MON PERIOD. HAVE CORRESPONDINGLY UPPED POPS THIS PERIOD.
DUE TO RECENT DRY SPELL AND EXPECTED WEAKENING WILL ISSUE A
HYDROLOGIC STATEMENT AS PONDING WOULD STILL OCCUR IF LOCALIZED
HIGH RATES ARE REALIZED.

SUNDAY NIGHT WILL SEE A CONTINUE OF PRECIPITATION WITH A DECREASE
IN THE HEAVY RAIN RISK AS EXPECTED CONVECTION MOVES ACROSS THE
CWFA.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 301 PM CDT SAT AUG 16 2014

FOR MONDAY THE RISK FOR HEAVY RAINS SHOULD SHIFT EAST. UPPER WAVE
CURRENTLY OVER NORTHERN MONTANA EXPECTED TO MOVE ALONG THE
INTERNATIONAL BORDER. THIS UPPER LOW TURNS INTO AN OPEN WAVE AND
PROGRESSES INTO MINNESOTA BY MONDAY NIGHT. THIS SHOULD PUSH THE
DEEPER MOISTURE AND INSTABILITY EAST OF OUR CWFA ENDING THE
PRECIPITATION.

FOR TUESDAY GUIDANCE IN GOOD AGREEMENT THAT 500 MB RIDGE BUILDS
INTO THE PLAINS AHEAD OF NEXT TROUGH OVER THE PACIFIC NORTHWEST.
SURFACE FLOW EXPECTED TO BE QUITE WEAK AND DRYING COLUMN SUGGESTS
A RAIN FREE AND WARMER DAY.

TUESDAY NIGHT-SATURDAY...MODELS ARE IN AGREEMENT THAT THIS PERIOD
WILL BEGIN DRY AS THE REGION WILL BE BETWEEN SYSTEMS...WITH WEAK
RIDGING OVERHEAD. THURSDAY AND INTO THE WEEKEND THERE WILL BE
MULTIPLE CHANCES FOR PRECIPITATION AS THE UPPER FLOW BECOMES
SOUTHWEST. TEMPERATURES DEPENDENT ON PRECIP CHANCES AND CLOUD
COVER...BUT SHOULD BE MOSTLY NEAR NORMAL VALUES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1143 PM CDT SAT AUG 16 2014

LEFT FOG IN AT MOST TAF SITES AROUND SUNRISE. NOT SURE IF THIS
WILL RESULT IN A LOW CLOUD DECK OR NOT...BUT IT MAY. IF IT DOES
RESULT IN A LOW CLOUD DECK IT MAY HOLD IN THROUGH THE REST OF THE
MORNING. TOUGH CALL. IF NOT THE MORNING SUN SHOULD RESULT IN SOME
LATE MORNING CUMULUS. BROUGHT IN A VICINITY TSTM MENTION IN THE
EVENING FOR TAF SITES ALONG AND WEST OF THE RED RIVER.

&&

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

$$

UPDATE...GODON
SHORT TERM...EWENS
LONG TERM...EWENS/TG
AVIATION...GODON






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