Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 291150
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
650 AM CDT MON SEP 29 2014

.UPDATE...
ISSUED AT 650 AM CDT MON SEP 29 2014

DELAYED THE CLEARING TREND...KEEPING CLOUDY CONDITIONS THROUGH
MUCH OF THE DAY. AS LOW LEVEL FLOW BECOMES EASTERLY...DRIER AIR
WILL ADVECT INTO THE REGION WITH CLOUD COVER ERODING FROM EAST TO
WEST. LATEST RAP/HRRR GUIDANCE HAS SLOWED THIS PROCESS A FEW
HOURS. LOWERED MAX TEMPS 1F-3F AS A RESULT OF THIS CHANGE. STILL
GETTING REPORTS OF DRIZZLE FROM AROUND THE REGION...AND WILL LEAVE
IN THE FORECAST THROUGH THE MID-MORNING HOURS (MODEL SOUNDINGS
SHOW SATURATED LAYER UP TO 850MB...WITH VERY DRY LAYER ABOVE
850MB...IDEAL DRIZZLE SOUNDING).

&&

.SHORT TERM...(TODAY THROUGH TUESDAY NIGHT)
ISSUED AT 355 AM CDT MON SEP 29 2014

THE MAIN CHALLENGE FOR TODAY WILL BE CLOUDS AND ASSOCIATED
TEMPERATURES. ON TUESDAY...THE CHALLENGE WILL FOCUS ON PRECIP
CHANCES...AND THE POTENTIAL FOR A STRONGER STORM ACROSS THE
SOUTHERN VALLEY. 00Z MODELS ARE IN DECENT AGREEMENT AND WILL USE
A BLEND FOR DETAILS.

TODAY-TONIGHT...SATELLITE IMAGERY INDICATES EXTENSIVE CLOUD COVER
AROUND THE REGION...EXTENDING WELL INTO CANADA. MODEL SOUNDINGS
INDICATE THAT THIS MOISTURE IS WITHIN THE SFC-850MB LAYER...AND
VERY DRY ABOVE 850MB. THE FLOW WITHIN THIS NEAR SURFACE LAYER IS
RELATIVELY WEAK THROUGH THE MORNING HOURS...INCREASING BY LATER
THIS AFTERNOON. RAP/HRRR GUIDANCE INDICATES THAT CIGS WILL BEGIN
TO ERODE THIS AFTERNOON. THE CURRENT FORECASTED MAX TEMPS (MID TO
UPPER 50S) ASSUME SOME SOLAR BY MID AFTERNOON...BUT IF THE CLOUDS
HANG ON LONGER THAN EXPECTED MAX TEMPS WILL NEED TO BE LOWERED.
THERE REMAINS PATCHY DRIZZLE AROUND THE REGION...WHICH WILL LIKELY
CONTINUE UNTIL MID-MORNING.

TUESDAY-TUESDAY NIGHT...STRONG UPPER/SFC LOW WILL PROPAGATE NORTHWARD
THROUGH THE CENTRAL DAKOTAS. MUCH OF TUESDAY MORNING WILL BE
DRY...WITH PRECIP CHANCES INCREASING FROM SOUTHWEST TO NORTHEAST
DURING THE AFTERNOON AND EVENING HOURS. THERE WILL BE AN AREA OF
DEFORMATION ZONE PRECIP ACROSS MAINLY THE WESTERN FA. A STRONG
850MB JET SHOULD LEAD TO A BAND OF NORTHEASTWARD MOVING CONVECTION
TO THE EAST OF THE UPPER/SFC LOW. INSTABILITY WILL BE WEAK...BUT
THE SOUTHERN VALLEY WILL BE ON THE NOSE OF THE SFC BASED
INSTABILITY...AND CONSIDERING THE STRONG DYNAMICS/DEEP LAYER SHEAR
A STRONGER STORM IS POSSIBLE HERE.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 405 AM CDT MON SEP 29 2014

WEDNESDAY-WEDNESDAY NIGHT...WEAK SFC RIDGING IN BETWEEN UPPER
SHORTWAVES SHOULD LEAD TO MOSTLY DRY WEATHER.

THURSDAY-SUNDAY...LONG WAVE PATTERN BEGINS SPLIT ACROSS NORTH
AMERICA. LONG WAVE TROUGH OVER THE NORTHERN PLAINS AND ANOTHER LONG
WAVE TROUGH OVER THE YUKON. LONG WAVE CONSOLIDATES OVER CENTRAL
NORTH AMERICA BY DAY 5 AND THEREAFTER. LONG WAVE TROUGH AXIS SHIFTS
EAST TO HUDSON BAY AND GREAT LAKES BY THE END OF THE PERIOD. THE
ECMWF IS THE FASTER SOLUTION AT THE BEGINNING OF THE PERIOD COMPARED
TO THE GFS AND REMAINS SO THROUGH THE PERIOD. BOTH THE GFS AND ECMWF
HAVE BEEN TRENDING SLOWER THE LAST COUPLE MODEL RUNS. WILL BLEND THE
GFS AND THE ECMWF.

WILL TRIM BACK POPS SOUTH THU AND IN THE EAST FRI.

TEMPS WERE LOWERED ONE TO THREE DEGREES FR FRI AND SAT. LITTLE
CHANGE TO THU AND SUN.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 650 AM CDT MON SEP 29 2014

LOW LEVEL WINDS WILL GRADUALLY SHIFT TO BECOME EASTERLY
TODAY...AND ADVECT DRIER AIR INTO THE REGION. THE LIFR/IFR CIGS
WILL GRADUALLY LIFT THROUGH THE DAY...BECOMING MAINLY MVFR BY
EARLY AFTERNOON. THESE CIGS SHOULD ERODE FROM EAST TO WEST THIS
AFTERNOON...WITH ALL SITES BECOMING VFR. USED RAP/HRRR GUIDANCE
FOR TIMING OF THIS SCENARIO.

&&

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

$$

UPDATE...TG
SHORT TERM...TG
LONG TERM...TG/HOPPES
AVIATION...TG



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