Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 191751 AAC
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1251 PM CDT TUE AUG 19 2014

.UPDATE...
SEE THE UPDATED 18Z AVIATION DISCUSSION BELOW.

NO SUBSTANTIVE CHANGES NEEDED FOR THE MORNING UPDATE. NUDGED HIGH
TEMPERATURES UP A COUPLE OF DEGREES GIVEN EXPECTED FULL INSOLATION
TODAY AND NEUTRAL TO WEAK WAA...ESPECIALLY ACROSS THE
CENTRAL/WESTERN TWO-THIRDS OF THE CWA. UPDATES ARE OUT.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH THURSDAY

CLEAR SKIES ACROSS THE CWA EARLY THIS MORNING AS HIGH PRESSURE AT
THE SURFACE MOVES INTO THE REGION. THIS SURFACE HIGH WILL DRIFT
EAST ACROSS THE AREA TODAY...BRINGING DRY CONDITIONS...MOSTLY
SUNNY SKIES AND RATHER LIGHT WINDS. LOW LEVEL JET WILL DEVELOP
LATE TONIGHT ACROSS WESTERN/SOUTHERN SOUTH DAKOTA WITH A BIT OF
ELEVATED INSTABILITY. WILL SEE PRECIP CHANCES INCREASING ACROSS
THE SOUTHWEST CWA LATE TONIGHT.

ATTENTION THEN TURNS TO WEDNESDAY WHICH IS SHAPING UP TO BE QUITE
INTERESTING. UPPER FLOW TURNS SOUTHWEST AS SHORTWAVE ENERGY ALOFT
MOVES OVERHEAD. AT THE SFC...LOW PRESSURE ALSO DEVELOPS OVER THE
REGION WHILE SOUTHEAST WINDS INCREASE AND BRING IN LOW LEVEL
MOISTURE. MODELS SHOWING MODERATE TO STRONG INSTABILITY DEVELOPING
OVER THE CWA WITH ABOUT 30 TO 40 KNOTS OF DEEP LAYER SHEAR. THERE
IS SOME CAPPING TO CONTEND WITH...BUT WILL LIKELY ERODE SOME BY
LATE AFTERNOON. SOME WEAK LOW LEVEL SHEAR IS EVEN SHOWING UP OVER
THE AREA AS WELL. SVR PARAMETERS LOOK GOOD...BUT THE BIG QUESTION
IN ALL THIS IS LINGERING CLOUD COVER FROM ANY POSSIBLE MORNING
CONVECTION. THERE ARE SOME INDICATIONS THAT THIS COULD BE THE
CASE...BUT DO NOT SEE MUCH AGREEMENT OR CONSISTENCY IN MODELS.
HAVE INCREASED POPS WEDNESDAY INTO WEDNESDAY NIGHT...WITH THE
THINKING THAT SEVERE STORMS ARE QUITE POSSIBLE AS WELL GIVEN THE
PARAMETERS. BUT AGAIN...THIS WILL ALL DEPEND ON CLOUD COVER AND
TIMING OF THE UPPER IMPULSE.

THURSDAY SHAPING UP TO BE A TRANQUIL DAY AS STORM SYSTEM WILL HAVE
EXITED THE REGION. THIS WILL BE A BREAK IN THE ACTION AS MORE
INCLEMENT WEATHER IS EXPECTED BY THE BEGINNING OF THE EXTENDED
PERIOD.


.LONG TERM...THURSDAY NIGHT THROUGH MONDAY

UPPER FLOW PATTERN WILL BE DOMINATED BY A BROAD TROF OVER THE PAC
NORTHWEST...A PATTERN THAT WILL CHANGE LITTLE OVER THE COURSE OF
THE EXTENDED. WILL INITIALLY SEE A SHORTWAVE EMBEDDED WITHIN
SOUTHWEST FLOW EARLY FRIDAY...AFTER WHICH TIMING ON THESE WAVES
BECOMES A TAD MORE DIFFICULT DUE TO UNCERTAINTY BETWEEN THE
DETERMINISTIC EC/GFS. THE EXTENDED IS TRENDING TOWARDS DRY AND
MUCH COOLER FOR SUNDAY AND INTO NEXT WEEK THANKS TO COLD ADVECTION
AHEAD OF A BROAD AREA OF CANADIAN HIGH PRESSURE. H85 READINGS END
UP AROUND A STANDARD DEVIATION BELOW CLIMO.

&&

.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL TERMINALS THROUGH
THIS TAF PERIOD. SOME CU HAS STARTED TO DEVELOP ACROSS OUR EAST SO
INCLUDED A SCT DECK AT ABR AND ATY THRU THE AFTERNOON. LIGHT WINDS
WILL GRADUALLY TURN MORE SOUTHERLY WITH TIME DURING THE PERIOD
AHEAD OF THE NEXT LOW PRESSURE SYSTEM DEVELOPING TO THE SOUTHWEST.
ADDED VCTS AT PIR AND MBG BEGINNING WED MORNING AS SOME OVERNIGHT
OR EARLY MORNING CONVECTION PROGRESSES FROM WEST TO EAST.

&&

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

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

WEATHER.GOV/ABERDEEN




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