Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 271145 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
645 AM CDT WED AUG 27 2014

.UPDATE...
SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH FRIDAY

SURFACE HIGH PRESSURE CONTINUES TO BACK OUT OF THE CWA...AND A
COUPLE OF WEAK SHOWERS/STORMS HAVE DEVELOPED ON THE NORTHERN
FRINGE OF WARM ADVECTION ACROSS FAR SOUTHERN COUNTIES THIS AM.

MAIN THREAT THIS FORECAST PERIOD IS THE POTENTIAL FOR HEAVY
RAIN TONIGHT/THURSDAY...UNFORTUNATELY WITH LOW CONFIDENCE THANKS
TO RATHER STRIKING DIFFERENCES BETWEEN THE NAM AND GFS.

NAM PROVIDES A MUCH BETTER JET SIGNATURE AND STRONGER MID LEVEL
FRONTOGENISIS...ALONG WITH A DEEPER LOW...AND A MORE NORTHERLY
TRACK. THIS PUSHES THE QPF BULLSEYE WELL INTO THE CWA. THE NAM
TREND HAS EXISTED SINCE 18Z AND IS CURRENTLY ENCOMPASSED WITHIN
THE 06Z RUN. SREF AND GEM/ECMWF HAVE A SOMEWHAT LESS NORTHERLY
EXTREME BUT THE SREF HAS PROBABILITIES GREATER THEN 2 INCHES FOR
THE SOUTHERN TIER OF THE CWA AND BOTH THE GEM/ECMWF BRING THE
PRECIPITATION BULLSEYE CLOSE ENOUGH TO THE CWA TO BE CONCERNED.
THE GFS IS THE SOUTHERLY OUTLIER.

NAM SUGGEST GENERALLY WEAK CONVECTION WITH MOIST ADIABATIC
PROFILES...AND LESS THEN 500 J/KG CAPE. THERE WILL BE ABOUT 20 TO
30 MICROBARS OF LIFT ALONG A NARROW EAST WEST AXIS WITH A SLOW
NORTHEAST MOVEMENT. SINCE STORMS ARE LIKELY DOMINATED BY WARM
CLOUD PROCESSES WITH SLOW EXPECTED MOTION...ADDED THE MENTION OF
HEAVY RAIN ACROSS FAR SOUTHEAST COUNTIES. AS THIS AREA OF THE CWA
HAS ESCAPED HEAVY RAIN IN THE PAST COUPLE OF DAYS...AND THE
UNCERTAINTY OVER EXACT LOCATIONS FOR STORMS...WILL OPT OUT OF ANY
FLOOD HEADLINES.


.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
MODELS REMAIN RELATIVELY SIMILAR AND MAINTAIN DECENT 24 HOUR
CONTINUITY. POPS CONTINUE TO BE SPRINKLED THROUGHOUT THE EXTENDED
WHILE FLATTER...MORE ZONAL-TYPE...UPPER FLOW PERSISTS. STILL
WATCHING SUNDAY AFTERNOON/EVENING AS A POSSIBLE ROUND OF STRONG
CONVECTION WITH A COLD FROPA AND MODERATELY STRONG MID-LEVEL
SHORTWAVE PROGGED. TEMPERATURES SHOULD BE RUNNING GENERALLY CLOSE
TO NORMAL FOR THIS TIME OF YEAR.


&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
IFR STRATUS HAS DEVELOPED THIS MORNING AT KPIR. IFR/MVFR FOG
AND/OR LOW STRATUS COULD STILL DEVELOP OVER THE NEXT HOUR OR TWO
MAINLY AT KMBG AND KABR AS WELL.

FLT CAT IS EXPECTED TO STEADY OUT IN MVFR RANGE /CIGS/ AT KPIR AND
KMBG THIS MORNING AND PERSIST FOR MUCH OF THE REST OF TODAY.
KABR AND KATY HAVE A HIGHER PROBABILITY OF MAINTAINING VFR FLYING
WEATHER CONDITIONS OVER THE NEXT 24 HOURS.

PRECIPITATION CHANCES START PICKING UP BY LATE THIS AFTERNOON AT
KPIR...PERSISTING WELL INTO THE EVENING...BEFORE SWITCHING OVER
AND BECOMING MOST PROBABLE AT KATY BY LATE THIS EVENING AND
PERSISTING OVERNIGHT.


&&

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

$$
UPDATE...DORN
SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...DORN

WEATHER.GOV/ABERDEEN




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