Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 221530 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1030 AM CDT WED MAY 22 2013

.UPDATE...REST OF TODAY
LOW PRESSURE CONTINUES TO SLOWLY MOVE AWAY FROM THE REGION...BUT
STILL CLOSE ENOUGH THAT WRAP AROUND LIGHT RAIN WILL PERSIST ACROSS
THE FAR EASTERN CWA THROUGH MUCH OF THE DAY. SKIES WILL BE CLOUDY
OR MOSTLY CLOUDY AS WELL...WITH THE CLEARING LINE SLOWLY ADVANCING
SOUTH THROUGH THE DAY. THE FAR NORTHERN CWA SHOULD START TO SEE
SOME PEEKS OF SUN LATER THIS AFTERNOON BUT AREAS FARTHER SOUTH
WILL STAY IN THE CLOUDS MOST OF THE DAY. THIS WILL ALSO AFFECT
HIGH TEMPERATURES. RATHER DIFFICULT HIGH TEMP FORECAST TODAY SINCE
IT ALL DEPENDS ON IF AND WHEN...AND HOW MUCH SUNSHINE WE SEE
ACROSS THE NORTHERN CWA. DID LOWER HIGHS A COUPLE DEGREES AS IT
APPEARS CLEARING WILL BE A BIT DELAYED. TEMPS AND SKY COVER WILL
BE THE FORECAST ISSUES TODAY AND EXPECT TO MAKE FURTHER
ADJUSTMENTS THROUGH THE DAY BASED ON SATELLITE TRENDS.


&&

.PREVIOUS DISCUSSION...

.SHORT TERM...TODAY THROUGH FRIDAY
THE LOW PRESSURE SYSTEM RESPONSIBLE FOR THE LAST SEVERAL DAYS OF
PRECIPITATION IS FINALLY SHOWING SIGNS OF EXITING THE REGION.
HOWEVER...THERE WILL BE ONE LAST WAVE OF ENERGY TO ROTATE AROUND
THE BACKSIDE OF THE LOW THIS AFTERNOON. SO WHILE CURRENT RADAR
IMAGERY IS SHOWING RAPID DIMINISHMENT OF REFLECTIVITY VALUES...THERE
WILL LIKELY BE REDEVELOPMENT ACROSS THE EASTERN CWA LATER THIS
MORNING...AND LIKELY LINGERING INTO THE AFTERNOON HOURS ACROSS THE
FAR SOUTHEAST CWA. MODELS ARE SHOWING DRIER AIR QUICKLY MOVING
ACROSS NORTH DAKOTA AND INTO THE NORTHERN CWA THIS AFTERNOON. THIS
SHOULD BREAK UP CLOUD COVER...AND COMBINED WITH WARM AIR ADVECTION
/925 MB TEMPS RISE BACK INTO THE TEENS ACROSS THE NORTH/
TEMPERATURES SHOULD BE ABLE TO RISE INTO THE MID TO UPPER 60S
ACROSS THE NORTH. MAINTAINED A LESS OPTIMISTIC TEMPERATURE
FORECAST FOR THE SOUTHERN CWA WHICH WILL LIKELY BE UNDER STRATUS
FOR MOST IF NOT ALL OF THE DAY.

A HIGH PRESSURE RIDGE THEN MOVES OVER THE REGION OVERNIGHT. WITH
CLEARING SKIES AND LIGHT WINDS...TEMPERATURES SHOULD DROP FAIRLY
QUICKLY...AND LOWS ARE FORECAST IN THE 40S.

THE RIDGE QUICKLY MOVES EAST DURING THE DAY ON THURSDAY...AND
RETURN FLOW WINDS WILL SET UP ACROSS THE CWA. WITH FULL SUN AND
925 MB TEMPERATURES BACK INTO THE TEENS...THE MODELS MAY BE UNDER
DOING TEMPERATURES SLIGHTLY ON THURSDAY. HOWEVER WITH THE BEST
WARM AIR ADVECTION NOT OCCURRING UNTIL LATE THURSDAY AND
FRIDAY...MAINTAINED THE MODEL CONSENSUS OF UPPER 60S AND LOW 70S
ACROSS THE REGION THURSDAY AFTERNOON. THE PRESSURE GRADIENT DOES
TIGHTEN UP QUICKLY ACROSS THE WESTERN HALF OF SOUTH DAKOTA AS LOW
PRESSURE DEVELOPING ACROSS THE NORTHERN ROCKIES DEEPENS AND MOVES
EASTWARD. SO...GUSTY SOUTHEAST WINDS WILL BE EXPECTED...ESPECIALLY
ACROSS THE WESTERN CWA.

BY THURSDAY NIGHT/FRIDAY MORNING THERE WILL BE A STRONG 30 TO
40 KNOT LOW LEVEL JET. UNCERTAIN IF THERE WILL BE ANY THUNDERSTORM
DEVELOPMENT ALONG THE LLJ AS THE MAIN SURGE OF GULF MOISTURE DOES
NOT MAKE ITS WAY INTO OUR CWA UNTIL FRIDAY AFTERNOON/SATURDAY.
EVEN WITH THE ADDITIONAL MOISTURE FRIDAY AFTERNOON...THE REGION
WILL STILL BE UNDER RISING 500 MB HEIGHTS...SO WILL CONTINUE TO
MONITOR FOR THUNDERSTORM DEVELOPMENT...BUT IT APPEARS AS MOST OF
THE LIFT WILL BE WARM AIR ADVECTION INDUCED AT THIS POINT.


.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
MODELS HAVE BEEN VERY CONSISTENT THROUGH THE WEEKEND WITH SOME
TIMING AND INTENSITY DIFFERENCES EMERGING AT THE START OF THE WORK
WEEK.

THE PERIOD BEGINS WITH A WIDE OPEN GULF OF MEXICO...A DEVELOPING
30 KT LLJ AND SOUTHEAST FLOW AT THE SFC AHEAD OF A LEE SIDE TROF.
THESE FACTORS WILL SET THE STAGE FOR SOME MILD INSTABILITY AND
THUNDERSTORMS FRIDAY EVENING. THE MOISTURE FEED AND POTENTIAL FOR
SHOWERS WILL CONTINUE INTO SATURDAY. THINK THE GFS ESPECIALLY MAY
BE OVERDOING THE POTENTIAL FOR RAIN INTO SUNDAY...THOUGH THERE ARE
A NUMBER OF SHORTWAVES MOVING UNDER THE UPPER RIDGE. ALLBLEND POPS
MAY BE A LITTLE HIGH BUT IT DOES LOOK LIKE A GOOD SET UP FOR
STRATUS BY THE END OF THE WEEKEND. WITH SOME INCREASED SUNSHINE
POTENTIAL ON MONDAY...DAYTIME INSTABILITY WILL AGAIN INCREASE THE
CHANCES FOR THUNDERSTORMS LATE MONDAY.

CURRENT MODEL RUNS ARE ONLY SLOWLY SHIFTING THE UPPER RIDGE TO THE
EAST TUESDAY WITH INCREASED SHORTWAVE ACTIVITY THROUGH WEDNESDAY.
MAX TEMPERATURES ARE EXPECTED TO BE MAINLY IN THE 70S THROUGH THE
PERIOD.


&&

.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

AN AREA OF RAIN SHOWERS WILL AFFECT MUCH OF EASTERN SOUTH DAKOTA
THROUGH THE MORNING. DURING THE AFTERNOON HOURS...THE RAIN SHOULD
BEGIN TO PUSH OFF TO THE EAST OF THE CWA. MVFR/IFR CIGS WILL BE
COMMON...THEN WILL RISE BACK INTO THE VFR CATEGORY BY EARLY
AFTERNOON IN THE WEST AND BY EVENING AT KATY.


&&

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

$$
UPDATE...TMT
SHORT TERM...SERR
LONG TERM...WISE
AVIATION...WISE

WEATHER.GOV/ABERDEEN





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