Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 221136 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
636 AM CDT WED APR 22 2015

.SHORT TERM...(TODAY THROUGH FRIDAY AFTERNOON)
ISSUED AT 345 AM CDT WED APR 22 2015

HIGH PRESSURE CONTINUES TO SAG SOUTH THIS MORNING...RESULTING IN
LIGHT WINDS ACROSS A MAJORITY OF THE CWA. THE EXCEPTION IS THE FAR
EASTERN CWA...WHERE THE GRADIENT REMAINS TIGHT AND NORTHWEST WINDS
REMAIN IN THE 10 TO 15 MPH RANGE. THE GRADIENT WILL GRADUALLY
SHIFT EAST TODAY...BUT NOT BEFORE GUSTY WINDS OCCUR OVER OUR
MINNESOTA COUNTIES LATER THIS MORNING AND EARLY IN THE
AFTERNOON. MIN RH VALUES WILL ALSO BE DROPPING INTO THE LOW
20S...BUT THE OVERLAP OF LOW RH AND STRONG WINDS APPEARS TO BE
BRIEF. COMBINED WITH HIGH TEMPERATURES ONLY FORECAST IN THE UPPER
40S TO LOW 50S...DID NOT CARRY ANY FIRE WEATHER HEADLINES. VERY HIGH
FIRE DANGER IS STILL EXPECTED HOWEVER...AND CONDITIONS WILL HAVE
TO BE MONITORED CLOSELY.

HIGH PRESSURE WILL BE THE DOMINANT FEATURE TONIGHT INTO THURSDAY
MORNING...SO AGAIN TRENDING TOWARD THE COOLER GUIDANCE FOR LOW
TEMPERATURES. RETURN FLOW WINDS ARE THEN EXPECTED TO SPREAD FROM
WEST TO EAST ACROSS THE CWA THURSDAY AFTERNOON. UNCERTAIN HOW
QUICKLY MOISTURE WILL ADVECT INTO THE REGION...AND WILL HAVE TO
MONITOR FIRE WEATHER CONDITIONS THROUGH THURSDAY AS WELL.

THE UPPER FLOW TRANSITIONS FROM NORTHWEST TO SOUTHWEST BY LATE
THURSDAY/FRIDAY. PERHAPS THERE IS SOME WEAK UPPER LEVEL ENERGY
MOVING UP FROM THE SOUTH...BUT WARM AIR ADVECTION APPEARS TO BE
THE MAIN SOURCE OF LIFT. REALLY UNSURE HOW QUICKLY SATURATION WILL
OCCUR IN THIS PATTERN...EVEN THOUGH MOST MODELS ARE TRYING TO
PRODUCE QPF. KEPT POPS IN THE SLIGHT CHANCE TO LOW CHANCE CATEGORY
FOR NOW.

.LONG TERM...(FRIDAY EVENING THROUGH TUESDAY)
ISSUED AT 345 AM CDT WED APR 22 2015

WHEN THE EXTENDED PERIOD OPENS...THERE IS A LONGWAVE TROF SUPPOSED
TO BE OVER THE WESTERN CONUS...WITH RATHER DIFFUSE
WEST-SOUTHWESTERLY UPPER LEVEL STEERING FLOW OVER THIS CWA. THERE
COULD BE A COUPLE OF WEAK S/W`S TRYING TO PUSH EASTWARD ACROSS THE
REGION BETWEEN FRIDAY NIGHT AND SUNDAY NIGHT. OTHERWISE...BOTH THE
00Z GFS AND ECMWF THIS MORNING AGREE THAT BY TUESDAY...THAT
WESTERN CONUS LONGWAVE TROF HAS BEEN REPLACED BY A LONGWAVE
RIDGE...WHICH PUTS THIS CWA BACK INTO MORE /PREDOMINANTLY COOL AND
DRY/ NORTHWEST FLOW ALOFT.

INTERESTINGLY ENOUGH...THE GFS/ECMWF 00Z SOLUTIONS ARE A BIT AT
ODDS BY TUESDAY REGARDING LOW LEVEL THERMAL ADVECTION. THE 00Z GFS
HAS BEEN DISREGARDED THIS MORNING FOR LONG-TERM TEMPERATURE
PROGS...GIVEN ITS OUTLANDISH /AND NOT SUPPORTED BY ANY OTHER
MODELS/ UPPER AIR PATTERN OVER THE WESTERN GREAT LAKES REGION BY
TUESDAY MORNING...IN FAVOR OF THE MORE SUB-DUED /REALISTIC/ ECMWF
MODEL AND ITS SLIGHTLY WARMER THERMAL ADVECTION PROGS FOR EARLY
NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 631 AM CDT WED APR 22 2015

GOOD VFR AND LIGHT WINDS WILL BE THE RULE TODAY AND TONIGHT WHILE
SURFACE HIGH PRESSURE IS IN PLACE ACROSS THE DAKOTAS.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$

SHORT TERM...SERR
LONG TERM...DORN
AVIATION...DORN






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