Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 271213 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
713 AM CDT WED MAY 27 2015

.UPDATE...
ISSUED AT 707 AM CDT WED MAY 27 2015

SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY AFTERNOON)
ISSUED AT 348 AM CDT WED MAY 27 2015

ONCE AGAIN TODAY...HI RES CAM SOLUTIONS ARE SHOWING ISOLATED WEAK
CELLS DEVELOPING OVER THE EASTERN CWA WITHIN WEAK INSTABILITY
REGION. UNLIKE YESTERDAY THOUGH WHEN CONVECTION DEVELOPED WITHIN A
SFC TROUGH...WE ARE RIGHT UNDER A SFC RIDGE TODAY. ALSO...ATMOSPHERE
IS A BIT DRIER. FEEL THE MODELS MAY BE OVERDOING THINGS A BIT
TODAY...BUT CANNOT COMPLETELY RULE OUT ANYTHING SO HAVE INCLUDED
SLIGHT CHANCE POPS A BIT FURTHER EAST INTO THE CWA FOR THE AFTERNOON
HOURS.

MAIN FEATURE THOUGH WILL BE THE UPPER LEVEL SHORTWAVE ENERGY MAKING
ITS WAY INTO WESTERN SD BY THIS AFTERNOON WITH EXPECTED SHOWER AND
THUNDERSTORM DEVELOPMENT. HI CONFIDENCE IN THIS SCENARIO WITH DECENT
LOOKING NEGATIVELY TILTED UPPER TROUGH AND GOOD AGREEMENT AMONGST
MODELS. INSTABILITY IS NOT REAL IMPRESSIVE...BUT GIVEN STRENGTH OF
WAVE AND THE EXISTENCE OF AT LEAST WEAK INSTABILITY...COULD SEE A
FEW STRONGER STORMS MAKING ITS WAY INTO THE WESTERN CWA BY LATE
AFTERNOON. WILL CONTINUE WITH RATHER HIGH POPS FROM LATE AFTERNOON
INTO EARLY EVENING OVER THE WESTERN CWA. REAL QUESTION COMES
OVERNIGHT IN DETERMINING OVERALL EASTWARD EXTENT OF PRECIP AND WHAT
AREAL COVERAGE WILL BE LIKE ONCE THINGS REACH THE JAMES VALLEY.
MODELS SUGGESTING THE BULK OF ACTIVITY MOVES ACROSS THE NORTHERN
COUNTIES AND INTO ND SO HAVE ADJUSTED POPS ACCORDINGLY. LOW LEVEL
JET STILL CRANKS UP OVERNIGHT OVER THE EAST...BUT NOSE OF JET IS NOW
ACROSS ND WHERE BETTER COVERAGE OF SHOWERS AND STORMS MAY END UP
BEING.

PRECIP CHANCES CONTINUE RIGHT INTO THURSDAY AND IN FACT...BETTER
INSTABILITY SETS UP AHEAD OF THE APPROACHING COLD FRONT. SEEMS
MODELS MAY HAVE SLOWED DOWN FRONTAL PROGRESSION JUST A BIT WHICH
WOULD GIVE MORE TIME FOR THE ATMOSPHERE TO DESTABILIZE. SVR
PARAMETERS SUPPORT POTENTIAL FOR STRONG TO SEVERE STORMS OVER
PORTIONS OF THE AREA. THE FRONT MOVES THROUGH THURSDAY NIGHT WITH
MUCH COOLER AIR TO FOLLOW FOR FRIDAY. BRISK NORTH WINDS ARE FORECAST
AS WELL WITH HIGHS MUCH COOLER AS TEMPS ONLY REACH THE 60S. COULD
VERY WELL BE DEALING WITH SHOWERS AT LEAST IN THE MORNING HOURS AS
SHORTWAVE ENERGY CONTINUES MOVING ACROSS THE REGION. THERE ARE SOME
DIFFERENCES NOTED IN THE MODELS IN REGARDS TO HOW THEY HANDLE THE
UPPER LEVEL ENERGY PASSING THROUGH ON FRIDAY. EC IS A BIT SLOWER
THAN THE GFS.

.LONG TERM...(FRIDAY EVENING THROUGH TUESDAY)
ISSUED AT 348 AM CDT WED MAY 27 2015

NO NOTE-WORTHY CHANGES FROM 24 HOURS AGO. AS THE PREVIOUS SHIFT
INDICATED...THE FIRST HALF OF THE PERIOD SHOULD BE DRY AND COOL AMID
AN AREA OF HIGH PRESSURE...BEFORE RETURN FLOW RE-INSTATES LOW LEVEL
MOISTURE INTO THE REGION HEADING INTO NEXT WEEK. THE GFS/ECMWF BOTH
INDICATE PLENTY OF CAPE/INSTABILITY AROUND NEXT WEEK...BUT ALSO SOME
WARM MID-LEVEL TEMPS /MODERATE TO STRONG CAPPING INVERSION/. NOT ALL
THAT CONFIDENT THAT THE CWA WILL SEE MUCH CONVECTION NEXT
WEEK...EVEN THOUGH THE MODELS INDICATE A SURFACE FRONT/SURFACE LOW
WILL BE AROUND MONDAY...TUESDAY AND WEDNESDAY OF NEXT WEEK...WITH
ONE OR MORE MID-LEVEL SHORTWAVES WORKING THROUGH THE REGION IN WEST-
NORTHWEST FLOW. GFS/ECMWF LOW LEVEL THERMAL PROGS INDICATE
TEMPERATURES COULD BE RATHER TOASTY NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 707 AM CDT WED MAY 27 2015

VFR CONDITIONS WILL PREVAIL TODAY AND TONIGHT. SCATTERED SHOWERS
AND THUNDERSTORMS WILL PUSH OVER THE WESTERN HALF OF THE CWA
DURING THE LATE AFTERNOON AND EVENING HOURS...LIKELY AFFECTING
KPIR AND KMBG. PRECIPITATION MAY HOLD TOGETHER LONG ENOUGH TO
REACH KABR AFTER 06Z THURSDAY. CIGS AND VSBYS MAY FALL INTO THE
MVFR CATEGORY WITH ANY THUNDERSTORMS THAT DEVELOP.

&&

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

$$

UPDATE...DORN
SHORT TERM...TMT
LONG TERM...DORN
AVIATION...DORN


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