436 
FXUS63 KFGF 270433
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1133 PM CDT THU SEP 26 2013

.UPDATE...
ISSUED AT 1126 PM CDT THU SEP 26 2013

MINIMAL CHANGES THIS UPDATE PERIOD. LATEST MODEL DATA CONTINUES TO
SUGGEST SOME DEVELOPMENT TO OUR SOUTH TONIGHT LIFTING NE. WARM
ADVECTION STEADILY INCREASING ACROSS EASTERN SOUTH DAKOTA AND LOW
LEVEL JET CONVERGENCE ALSO SPREADING INTO EASTERN SD. WHILE
INSTABILITY WEAK FEEL SOME ACTIVITY POSSIBLE DURING THE OVERNIGHT
AND WILL MAINTAIN CURRENT POPS. SURFACE BOUNDARY HAS MOVED LITTLE
SINCE LAST UPDATE PERIOD AND TEMPERATURES REMAIN ON TRACK. 

UPDATE ISSUED AT 930 PM CDT THU SEP 26 2013

BOUNDARY CONTINUES TO DRIFT EAST NOW GENERALLY THROUGH THE VALLEY.
LAST FEW HOURS BOUNDARY HAS SLOWED UP AND PROBABLY NOT LIKELY TO
MOVE MUCH FARTHER EAST OVERNIGHT. OVERALL CURRENT TEMPERATURES IN
LINE WITH BOUNDARY TIMING SO WILL MAINTAIN CURRENT MINIMUMS WITH
COOLEST READINGS FROM NORTHERN VALLEY SSW TO WESTERN FA. PER SPC
MESOSCALE ANALYSIS LOW LEVEL JET CONVERGENCE NOW INTO SW MN WITH
WARM ADVECTION SHIFTING EASTWARD INTO WESTERN/CENTRAL MN. WITH
THESE FAVORED FEATURES FOR ELEVATED CONVECTION A TAD FARTHER EAST
AND NOTHING YET ON RADAR PULLED POPS ACROSS THE SOUTH UP TO 06Z.
WILL MAINTAIN POPS AFTER 06Z WITH BOUNDARY IN PLACE AND WEAK LIFT
ALONG AND AHEAD OF THE BOUNDARY. 

UPDATE ISSUED AT 646 PM CDT THU SEP 26 2013

NO CHANGES FOR THIS UPDATE PERIOD. MESOSCALE MODELS CONTINUE TO
INDICATE POTENTIAL FOR SOME CONVECTION LATER TONIGHT ACROSS THE
SE FA AS LOW LEVEL JET CONVERGENCE INCREASES IN ZONE OF WARM
ADVECTION.  WILL MAINTAIN POPS.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY) 
ISSUED AT 315 PM CDT THU SEP 26 2013

RAIN CHANCES AND AMOUNTS WILL BE THE MAIN CHALLENGE. NOT MUCH HAS
CHANGED WITH THE PREVIOUS THINKING AND ONLY MINOR CHANGES ARE
NEEDED TO THE FORECAST. 12Z MODELS ARE IN GOOD
AGREEMENT...ESPECIALLY THE ECMWF/GEM/GFS. THE NAM HAS TRENDED TO
BE THE DEEPEST/SLOWEST/FURTHEST WEST SOLUTION. THE GENERAL IDEA IS
THAT AS THE UPPER TROUGH APPROACHES THE REGION TONIGHT AND
FRIDAY...THERE WILL BE A COUPLE WEAK WAVES EJECTING INTO THE
REGION. MODELS ARE HAVING A DIFFICULT TIME HANDLING THESE WEAK
LEAD WAVES...AND THERE IS NO CLEAR SIGNAL FOR THE BEST TIMING OF
SHOWERS TONIGHT AND FRIDAY. STARTED OFF WITH 20-30 POPS ACROSS THE
SE FA TONIGHT...AND EXPANDED/INCREASED POPS ON FRIDAY. KEPT THE
COVERAGE AS SCATTERED...AND IF THE SIGNALS BECOME CLEARER THEN POPS
CAN BE INCREASED. THE TROUGH/UPPER LOW SWINGS THROUGH THE REGION
FRIDAY NIGHT INTO SATURDAY...GIVING A STRONG SIGNAL FOR RAIN.
THERE WILL BE STRONG SYNOPTIC FORCING COMBINED WITH PWATS 1.25 TO
1.50 INCHES...AS WELL AS MESOSCALE MID-LEVEL FRONTOGENETICAL
FORCING. 12Z MODEL GUIDANCE INDICATES THE HEAVIEST BAND OF RAIN
WILL BE FROM SOUTHEAST NORTH DAKOTA INTO THE ROSEAU AREA. GIVEN
THE AVAILABLE MOISTURE AND EXPECTED STRONG FORCING (AND MODEL
QPF)...ONE TO TWO INCHES OF RAIN WITHIN THIS BAND APPEARS
LIKELY...WITH LIGHTER AMOUNTS ON EITHER SIDE. THE AIRMASS SHOULD
BE STABLE AS THE HEAVIEST BAND OF RAIN FALLS...WHICH WOULD LIMIT
RAINFALL AMOUNTS. THE CURRENT SOILS SHOULD BE ABLE TO HANDLE A
COUPLE INCHES OF RAIN OVER A PERIOD OF 6-12 HOURS. THE RAIN WILL
END FROM WEST TO EAST SATURDAY AFTERNOON AS THE SYSTEM MOVES OFF
TO THE NORTHEAST. FUTURE FORECASTS WILL BE ABLE TO FURTHER TWEAK
THE EXACT PLACEMENT AND EXTEND OF THE HEAVIEST BAND OF RAINFALL. 

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) 
ISSUED AT 315 PM CDT THU SEP 26 2013

SATURDAY NIGHT-SUNDAY...UPPER FLOW WILL BE MORE ZONAL WITH
SOUTHERLY LOW LEVEL FLOW AND A WARMING AIRMASS. THE WEATHER
SHOULD BE DRY.

SUNDAY NIGHT-THURSDAY...LONG TERM MODELS ARE IN SOMEWHAT
AGREEMENT THROUGH DAY 6...WITH A SW FLOW PATTERN BECOMING MORE
ZONAL BY THE END OF THE PERIOD WITH THE ECMWF...BUT REMAINING SW
ALOFT WITH THE GFS. BIGGEST DIFFERENCE BETWEEN THE MODELS IS ECMWF
BEING FURTHER SOUTH WITH PRECIP ASSOCIATED WITH A H500 LOW MOVING
ACROSS NORTHERN MANITOBA TUE NIGHT INTO WED...CLIPPING THE
NORTHERN THIRD OF OUR CWA. HAVE REMOVED POPS YIELDED FROM THE
CONSALL SOLUTION AS CONTINUITY...THE GFS AND THE GEM ARE ALL DRY.
MODELS IN BETTER AGREEMENT WITH PRECIP IMPACTING SOUTHERN ZONES
NEAR THE END OF THE PERIOD...BUT KEPT CHANCE CATEGORY DESPITE
CONSALL INCREASING POPS TO LIKELIES...TO FAR OUT TO BE THAT
CONFIDENT. DAYTIME TEMPS SHOULD RANGE FROM THE UPPER 60S TO THE
LOWER 70S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1126 PM CDT THU SEP 26 2013

AFTER A DECREASE IN VFR CIGS EARLIER THIS EVENING EXPECT CIGS TO
INCREASE OVERNIGHT BUT REMAIN IN VFR RANGE THROUGH THE PERIOD.
STARTED TO MENTION SHRA/SHRA VCNTY LATE TONIGHT/TOMORROW AS
POSSIBLE SHRA TO OUR SOUTH LIFT NORTHWARD. 

&&

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

$$

UPDATE...VOELKER
SHORT TERM...TG
LONG TERM...TG/SPEICHER
AVIATION...VOELKER