Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 280220 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
920 PM CDT WED MAY 27 2015

.UPDATE...
ISSUED AT 918 PM CDT WED MAY 27 2015

AN AREA OF SHOWERS AND THUNDERSTORMS NOW AFFECTING THE COUNTIES ON
EITHER SIDE OF THE MISSOURI RIVER. BIGGEST THREATS LOOK TO BE
OCCASIONAL MODERATE TO HEAVY RAIN AND FREQUENT LIGHTNING STRIKES.
HAVE ADJUSTED POP AND WEATHER GRIDS ACCORDINGLY. NO OTHER CHANGES
MADE TO THE FORECAST AT THIS TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 350 PM CDT WED MAY 27 2015

WEAK SHOWERS OVERHEAD EXIST THANKS TO AMPLE SUN AND COOL MID LEVEL
TEMPERATURES...BUT ARE EXPECTED TO WEAKEN WITH INCREASED MID/HIGH
CLOUDS AND WARMER MID LEVEL TEMPERATURES. FOCUS SHIFTS WEST RIVER
WHERE MID LEVEL WARM ADVECTION IS RESPONSIBLE FOR A FEW ELEVATED
SHOWERS...PROBABLY NOT REACHING THE GROUND HOWEVER. SURFACE BASED
CONVECTION HAS DEVELOPED WITHIN UNR CWA THOUGH...AND MODELS
SUGGEST THESE WILL CONTINUE TO PUSH NORTH AND EAST AS A WAVE
EJECTS INTO THE NORTHERN PLAINS. THERE IS A RATHER TIGHT GRADIENT
IN MUCAPE OVERNIGHT...SO AS STORMS PUSH INTO CENTRAL SOUTH
DAKOTA...EXPECT A PRECIPITOUS DROP OFF IN COVERAGE/INTENSITY. THIS
IS FAIRLY WELL DEPICTED IN OUR LATEST SUITE OF HIGH RESOLUTION
GUIDANCE...DESPITE THE EXISTENCE OF A 40KT LOW LEVEL JET AND
UPWARDS OF 1000 J/KG MUCAPE.

SURFACE LOW PRESSURE MOVES THROUGH NORTH DAKOTA EARLY
THURSDAY...WITH A TRAILING COLD FRONT INTO NORTH CENTRAL SOUTH
DAKOTA. THIS WILL PROVIDE THE MAIN FOCUS FOR CONVECTION AS A SECOND
WAVE EJECTS INTO SOUTH DAKOTA...THOUGH PRE FRONTAL CONVECTION ALSO
POSSIBLE. MLCAPE VALUES TOP 2000 J/KG...WITHIN A LIGHT
UNIDIRECTIONAL SHEAR ENVIRONMENT. COOLER AIR UNDERCUTS OUR UNSTABLE
AIRMASS THURSDAY NIGHT WITH DRY/COOL CONDITIONS FOR FRIDAY.


.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 350 PM CDT WED MAY 27 2015

GOOD AGREEMENT WITH THE MODELS DURING THE LONG TERM WITH THE SURFACE
AND UPPER LEVEL FLOW ACROSS THE REGION. THE LONG TERM BEGINS WITH
SURFACE HIGH PRESSURE CENTERED OVER THE REGION BRINGING A COOL AND
DRY SATURDAY. THIS SURFACE HIGH PRESSURE BUILDS EAST AS WARMER AIR
RETURNS WITH UPPER LEVEL HEIGHTS BUILDING OVER OUR REGION INTO NEXT
WEEK. THUS...EXPECT TEMPERATURES TO WARM FROM SUNDAY THROUGH
TUESDAY. HIGHS WILL BE MAINLY IN THE 80S ON TUESDAY. OTHERWISE...THE
MODELS SHOW SEVERAL SHORT WAVE TROUGHS FROM THE WEST SLIDING OVER
OUR REGION THROUGH THE LONG TERM BRINGING OFF AND ON CHANCES OF
SHOWERS/STORMS. IT DOES LOOK LIKE A SURFACE FRONTAL ZONE WILL BE
PUSHING INTO THE REGION FROM THE WEST FOR TUESDAY AND WEDNESDAY
BRINGING IN BETTER CHANCES OF SHOWERS/STORMS TO THE CWA.


&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 624 PM CDT WED MAY 27 2015

SCATTERED SHOWERS WILL AFFECT MAINLY THE WESTERN AND CENTRAL
PORTIONS OF THE CWA THIS EVENING AND OVERNIGHT...WITH A FEW
THUNDERSTORMS POSSIBLE ALONG AND WEST OF THE MISSOURI RIVER. AFTER
A QUIET MORNING ON THURSDAY...LOOK FOR SHOWERS AND THUNDERSTORMS
TO REDEVELOP ACROSS MAINLY THE CENTRAL AND EASTERN CWA. CONDITIONS
WILL GENERALLY BE VFR THROUGH THE TAF PERIOD...BUT BRIEF PERIODS
OF MVFR CIGS AND VSBYS ARE POSSIBLE WITH ANY THUNDERSTORMS THAT
DEVELOP.

&&


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

$$

UPDATE...PARKIN
SHORT TERM...CONNELLY
LONG TERM...MOHR
AVIATION...PARKIN



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