000
FXUS63 KABR 171716 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1216 PM CDT FRI MAY 17 2013

.UPDATE...
STRATUS DECK EXTENDING FROM CENTRAL INTO NORTHEAST SD EXPECTED TO
LIFT AND CU OUT THROUGH THE AFTERNOON. THUS...EXPECT IT TO BE MORE
STABLE INTO THE EARLY AFTERNOON WITH INCREASING INSTABILITY
THROUGH THE LATE AFTERNOON DEVELOPING. THE HI-RES MODELS HOLD OFF
ON ANY THUNDERSTORM/SHOWER DEVELOPMENT UNTIL LATER THIS AFTERNOON
AND EVENING. THUS...TOOK OUT POPS UNTIL LATER THIS AFTERNOON AND
EVENING. UPDATED FORECAST.

AVIATION DISCUSSION UPDATED BELOW...

&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SUNDAY
THE THREAT OF SEVERE STORMS TODAY AND AGAIN SATURDAY WILL BE THE
MAIN FORECAST CHALLENGE.

THE UPPER LEVEL FLOW PATTERN CONSISTS OF A RIDGE ACROSS THE CENTRAL
CONUS...WITH A TROUGH OVER SOUTHERN CALIFORNIA. THIS TROUGH WILL
CONTINUE TO TRACK TOWARDS THE FOUR CORNERS REGION OVER THE NEXT
36 HOURS. THIS UPPER LEVEL FEATURE...ALONG WITH INCREASING LLM
FROM THE GULF WILL PRODUCE TWO PERIODS OF SEVERE STORMS ACROSS THE
CWA.

THE FIRST CHANCE OF SEVERE WEATHER WILL BE LATER THIS EVENING
FOR AREAS ACROSS THE SOUTHWEST PORTION OF THE CWA. SURFACE DEW
POINTS ALONG A WARM FRONT DRAPED EAST/WEST ACROSS SOUTHERN SOUTH
DAKOTA WILL BE THE FOCUS MECHANISM FOR CONVECTION. SURFACE LOW
PRESSURE OVER NW NEBRASKA WILL PRODUCE MOISTURE ADVECTION INTO THE
BLACK HILLS REGION. THUNDERSTORMS DURING THE AFTERNOON HOURS WILL
LIKELY TRACK EAST SOUTHEAST ALONG THE WARM FRONT/INSTABILITY AXIS
THIS EVENING...REACHING KPIR/K9V9 BETWEEN 3-6Z. A FEW STORMS MAY
PRODUCE GUSTY WINDS AND SMALL HAIL. WHILE THE SEVERE POTENTIAL
SEEMS TO WANE AFTER 3Z...THUNDERSTORMS SHOULD CONTINUE TO TRACK
ACROSS THE REST OF THE CWA DUE TO AN INCREASING LLJ.

SOUTHWEST FLOW ALOFT WILL CONTINUE THROUGH THE DAY ON
SATURDAY...WHICH WILL DRAW MID 60S SURFACE DEW POINTS INTO THE CWA.
HIGH TEMPERATURES SHOULD QUICKLY WARM ACROSS EASTERN SOUTH
DAKOTA...WITH THE MID LEVEL CAPPING BEING OVER COME DURING THE MID
AFTERNOON HOURS. HI-RES MODELS GENERALLY SUPPORT THE IDEA OF
CONVECTION DEVELOPING MUCH SOONER THAN ORIGINALLY EXPECTED...OR
BETWEEN 18-21Z. WHILE EARLIER INITIATION MAY LIMIT THE OVERALL
SEVERE THREAT...DISCRETE SUPERCELLS WILL STILL BE POSSIBLE. LARGE
HAIL AND ISOLATED TORNADOES ARE POSSIBLE DURING THE ONSET OF
CONVECTION.

AN ADDITIONAL THREAT FOR SEVERE STORMS WILL BE POSSIBLE ON SUNDAY
AS A STRONG COLD FRONT MOVES ACROSS THE REGION. THE BEST
INSTABILITY AXIS BY 0Z MONDAY CURRENTLY LIES ALONG THE I-29
CORRIDOR. THANKFULLY 0-6KM BULK SHEAR VALUES ARE VERY WEAK ALONG
THE INSTABILITY AXIS WHICH MAY LIMIT THE OVERALL SEVERE THREAT.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

STILL GOOD AGREEMENT AMONG THE MODELS IN THE LONG TERM FOR A WET
START TO THE EXTENDED PERIOD. A SFC LOW WILL OCCLUDE OVER THE
NORTHERN PLAINS SUNDAY NIGHT AND MONDAY WHILE THE UPPER LOW
CATCHES UP TO IT. PRECIP WILL REINTENSIFY WITH THE ADDITION OF THE
UPPER TROF AND CAA. IF THE GFS IS CORRECT WILL LIKELY NEED TO
INCREASE THE WINDS WITH THIS SYSTEM ON MONDAY. AT THE MOMENT MAIN
IMPACTS AT THE SFC WILL BE CONTINUED RAIN WITH SOME TSTORMS ONLY
SLOWLY EXITING TO THE EAST ON WEDNESDAY AND MUCH COOLER TEMPS
BEHIND THE LOW. TEMPS WILL FALL BACK INTO THE 60S FOR HIGHS EVEN
AS AN UPPER RIDGE BUILDS INTO THE PLAINS TOWARD THE END OF THE WEEK.






&&

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

VFR CONDITIONS FOR KABR/KMBG...WITH KATY/KPIR MIXING OUT MVFR
CIGS BY THE EARLY AFTERNOON. A FEW WEAK SHOWERS COULD
DEVELOPS AT KABR/KATY THIS AFTERNOON WITH NEGLIGIBLE EFFECT. MAIN
THREAT WILL BE STORMS PUSHING INTO THE KPIR/KMBG TERMINALS DURING
THE EVENING. THIS AREA OF CONVECTION WILL THEN POSSIBLY IMPACT
KABR/KATY TERMINALS OVERNIGHT. THERE IS THE POSSIBILITY THAT
CONVECTION WILL LEAVE US WITH MVFR CIGS BY THE MORNING...THOUGH
WITH LOW FORECASTER CONFIDENCE. WINDS WILL BE OUT OF THE
EAST/SOUTHEAST...BUT WILL INCREASE IN INTENSITY SOMEWHAT AS THEY
SHIFT TO DUE SOUTH EARLY SATURDAY.


&&

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

$$
UPDATE...MOHR
SHORT TERM...SD
LONG TERM...WISE
AVIATION...CONNELLY

WEATHER.GOV/ABERDEEN