Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 220849
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
349 AM CDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY AFTERNOON)
ISSUED AT 346 AM CDT FRI MAY 22 2015

CLOUDS ARE INCREASING ACROSS FAR SOUTHWEST SOUTH DAKOTA THIS MORNING
AS THE NEXT UPPER LEVEL SHORTWAVE APPROACHES THE REGION. CURRENT
WATER VAPOR IMAGERY SUGGESTS THIS FEATURE IS MOVING OVER NORTHEAST
NEW MEXICO...INTO SOUTHERN COLORADO. THE TIMING OF THIS FEATURE AS
IT PROGRESSES NORTHWARD ISNT COMPLETELY AGREED UPON BETWEEN MODELS.
EITHER WAY HOWEVER...CLOUD COVER SHOULD MOVE INTO THE SOUTHWESTERN
CWA EARLY THIS AFTERNOON...KEEPING HIGH TEMPS A FEW DEGREES COOLER
THAN THE NORTHEAST CWA. WINDS WILL ALSO BE BREEZY ACROSS THE WESTERN
HALF OF SOUTH DAKOTA AS THE PRESSURE GRADIENT TIGHTENS UP.

POPS RETURN TO THE FORECAST LATE TONIGHT AS THE ABOVE MENTIONED
SHORTWAVE NEARS THE REGION. WHILE CURRENTLY WELL DEFINED...MODELS DO
SHOW THE FORCING WITH THIS FEATURE BECOMING MORE DIFFUSE AS IT
TRACKS NORTH. ADDITIONAL POPS ARE THEN FORECAST SATURDAY AS ENERGY
KICKS OUT AHEAD OF THE MAIN UPPER LOW. THERE WILL LIKELY BE A BREAK
IN PRECIP BETWEEN THE TWO...BUT HARD TO PINPOINT EXACTLY WHEN THAT
MAY OCCUR. MOISTURE DOES INCREASE NICELY...WITH A SATURATED COLUMN
SATURDAY AND SUNDAY...AND PWATS PEAKING AROUND 1.3 INCHES SUNDAY
MORNING. BECAUSE SEVERAL WAVES OF ENERGY PASS OVER THE REGION IT IS
LIKELY THERE WILL BE ON AND OFF PERIODS OF RAINFALL...BUT VERY HARD
TO PINPOINT ANY DISTINCT DRY PERIODS...SO POPS OVERALL ARE
BROADBRUSHED. THE STRONGEST FORCING/HIGHEST POPS RESIDE IN THE
SATURDAY NIGHT/SUNDAY MORNING TIME FRAME. OVERALL IT IS A PRETTY
STABLE SYSTEM...SO GENERAL THUNDER REMAINS THE THEME.

.LONG TERM...(SUNDAY EVENING THROUGH THURSDAY)
ISSUED AT 346 AM CDT FRI MAY 22 2015

WHEN THE PERIOD OPENS...AN ACTIVE/WET PATTERN IS ALREADY IN PROGRESS
OVER THE REGION. THIS SEEMS TO BE THE GENERAL CONSENSUS AMONGST
LONGER RANGE GSM OUTPUT. BY ABOUT HALFWAY THROUGH THE PERIOD...THE
GFS MODEL BEGINS TO DIVERGE FROM THE EC/GEM IN ITS HANDLING OF UPPER
LEVEL FLOW PATTERN EVOLUTION. THE ECMWF APPEARS TO HAVE SUPPORT OF
THE CANADIAN IN TERMS OF THE FLOW PATTERN JUST RESETING TO WEST-
SOUTHWESTERLY WITH MORE S/W ENERGY MOVING OUT OVER THE REGION. THE
GFS FINALLY COMES BACK AROUND TO SWRLY FLOW /LIKE THE OTHER MODEL
SOLUTIONS/ ALOFT BY DAY 7...INCLUDING ADDITIONAL PRECIP CHANCES FROM
MORE TRANSIENT S/W ENERGY WORKING THROUGH. SUPERBLEND POPS IN THIS
ACTIVE PATTERN ARE SMEARING THE ENTIRE PERIOD WITH POPS...LIKELY A
BI-PRODUCT OF RUN-TO-RUN TIMING DIFFERENCES OF ALL THESE LITTLE
TRANSIENT S/WS FORECAST TO MOVE OVER THE CENTRAL/NORTHERN PLAINS
STATES. IF THERE WAS A TIME PERIOD WHEN RAIN CHANCES ARE LITTLE TO
NONE...BASED OFF TONIGHT`S DETERMINISTIC MODEL SOLUTIONS...IT WOULD
LIKELY BE LATE TUESDAY AFTERNOON THROUGH EARLY WEDNESDAY EVENING.
THE GFS/ECMWF LOW LEVEL THERMAL PROGS ARE NOT ALL THAT SIMILAR
EITHER THIS GO ROUND. WILL STICK WITH SUPERBLEND FOR THIS FORECAST
PACKAGE AND SEE IF MODELS ARE IN ANY BETTER AGREEMENT IN 24 HOURS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1243 AM CDT FRI MAY 22 2015

VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS THROUGH THE ENTIRE
VALID TAF TIME PERIOD. A FEW SHOWERS MAY MAKE THEIR WAY INTO THE
KPIR AREA FRIDAY EVENING.

&&

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

$$

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



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