Area Forecast Discussion
Issued by NWS Aberdeen, SD

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765
FXUS63 KABR 170533 AAC
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1233 AM CDT SUN MAY 17 2015

.UPDATE...
ISSUED AT 1230 AM CDT SUN MAY 17 2015

SEE UPDATED AVIATION DISCUSSION BELOW.


&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 301 PM CDT SAT MAY 16 2015

STORMS HAVE BEGUN TO PULSE ALONG THE WARM FRONT WITH AN AIRMASS THAT
CONTINUES TO WARM THROUGH FILTERED CLOUD COVER. SEVERE POTENTIAL
REMAINS THANKS TO FAVORABLE SHEAR ENVIRONMENT...AND INCREASING CAPE
MAINLY ALONG AND NORTHEAST OF A LINE FROM KPHP KPIR TO KHON.

THE ASSOCIATED WEAK WAVE CONTINUES TO DRIFT NORTH THIS
AFTERNOON/EVENING...WITH A LESS FAVORABLE UPPER LEVEL ENVIRONMENT
FOR A FEW HOURS BEFORE THE NEXT WAVE IN CENTRAL NEBRASKA LIFTS NORTH
AND WEAKENS. THE MAIN UPPER FEATURE PIVOTS UP INTO THE CWA SUNDAY
AM...WITH A Q VECTOR BULLSEYE OVER THE CWA. SREF PROBABILITIES FOR
EXCEEDING 1 TO 2 INCHES OF RAIN ARE NEAR 80 AND 30 PERCENT
RESPECTIVELY...WITH MOST GUIDANCE SET ON THE JAMES VALLEY RECEIVING
THE HEAVIEST RAINFALL. AS THE UPPER TROF CONTINUES NORTHEAST...WE
WILL SEE FAR EASTERN COUNTIES GET INTO THE WARM SECTOR...A HIGH
SHEAR LOW CIN ENVIRONMENT WHERE ANY DAYTIME HEATING WILL LEAD TO
RAPID DESTABILIZATION...ALBEIT WELL AHEAD OF THE COLD FRONT.
THUS...BROUGHT IN A LATE MORNING MENTION OF SEVERE FOR EASTERN
SD/WESTERN MN SUNDAY.

AS THE UPPER LOW MOVES EAST...WILL SEE STRONG COLD ADVECTION WITH
850MB WINDS APPROACHING 50KTS. MIXED DOWN WINDS ARE WELL WITHIN
ADVISORY CRITERIA. GFS 850MB TEMPS FALL TO -4C...WITH THE ECMWF
STILL AROUND -7C. NAM LOW LEVEL ENVIRONMENT SUGGESTS THE POTENTIAL
FOR GRAUPLE SHOWERS WITH DAYTIME HEATING MONDAY UNDER THIS VERY COLD
ENVIRONMENT. THE GRADIENT MAY REMAIN STRONG ENOUGH FOR LIGHT WINDS
TO PERSIST THROUGH PARTS OF TUESDAY MORNING IN THE EAST...WHERE
850MB WINDS ARE COLDEST...WHILE IN THE WEST THE HIGH CENTER MOVES
OVERHEAD FOR FAVORABLE RADIATIONAL CONDITIONS. WHILE FREEZE
POTENTIAL IS MARGINAL FOR MONDAY MORNING...IT LOOKS ALMOST CERTAIN
FOR TUESDAY MORNING.


.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 301 PM CDT SAT MAY 16 2015

NOT MUCH HAS CHANGED IN THE EXTENDED FORECAST COMPARED TO 24 HOURS
AGO. STILL LOOKS A BIT COOLER THAN CLIMO NORMAL AS THE PERIOD OPENS
WITH COOL DRY CANADIAN HIGH PRESSURE OVER THE REGION. STILL SOME
QUESTION AS TO HOW COLD IT CAN GET BY TUESDAY MORNING...BUT FOR NOW
WILL CONTINUE TO MONITOR TEMPERATURE FORECAST TRENDS IN CASE THERE
IS A NEED FOR A FROST OR FREEZE HEADLINE HEADING INTO TUESDAY
MORNING. OTHERWISE...IT STILL LOOKS LIKE THE FLOW PATTERN WILL
RECYCLE BY MID TO LATE WEEK WITH ONE AREA OF LOW PRESSURE SKIRTING
THE CWA ANCHORED MAINLY ON WEDNESDAY AND STILL MAINLY ACROSS THE
SWRN FORECAST ZONES...AND THEN ANOTHER SHIFT IN THE FLOW ALOFT TO
SOUTH-SOUTHWESTERLY BY NEXT WEEKEND WITH ADDITIONAL SHOWER AND
THUNDERSTORM CHANCES RAMPING UP AS TEMPERATURES RECOVER TO CLOSER TO
NORMAL IN LOW LEVEL SOUTHERLY RETURN FLOW.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1230 AM CDT SUN MAY 17 2015

SHOWERS AND TSTMS NEAR KPIR WILL TAPER OFF OVER THE NEXT COUPLE
OF HOURS. ANOTHER SURGE OF SHOWERS AND TSTORMS WILL MOVE INTO THE
REGION BETWEEN 09Z AND 12Z. STILL SOME UNCERTAINTY REGARDING
WHERE THE HEAVIEST PRECIP WILL OCCUR THOUGH IT APPEARS ALL SITES
WILL FALL TO MVFR CIGS. THERE WILL BE OCCASIONAL IFR VSBY IN
HEAVIER SHOWERS.

&&


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

$$

SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...PARKIN



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