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000
FXUS63 KABR 170838
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
338 AM CDT MON JUN 17 2013

.SHORT TERM...TODAY THROUGH WEDNESDAY
PRECIPITATION CHANCES THROUGH OUT THE PERIOD WILL BE THE MAIN
FORECAST CHALLENGE.

A MOISTURE GRADIENT STRETCHING FROM WESTERN SOUTH DAKOTA...TO
EASTERN NEBRASKA...ALONG WITH A WEAK UPPER LEVEL IMPULSE WILL
RESULT IN SCATTERED THUNDERSTORMS FOR THE EXTREME SW CWA THIS
MORNING. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
LATER THIS AFTERNOON OVER THE EXTREME NE PORTION OF THE CWA. WEAK
INSTABILITY ON THE CAA SIDE OF A HIGH PRESSURE WILL LIKELY RESULT
IN STEEP LOW LEVEL RATES. HI-RES MODELS PLUS THE NAM12 HAS SHOWN
WEAK COMPOSITE REFLECTIVITY REACHING SISSETON BETWEEN 21-03Z THIS
AFTERNOON. WITH SUNSET WELL AFTER 0Z...THESE DIURNALLY DRIVEN
SHOWERS SHOULD CONTINUE UNTIL AT LEAST 3Z BEFORE DIMINISHING.

THE HI-RES NMM/ARW...PLUS THE NAM12 AND THE NSSL WRF ALL SUGGEST
ACCAS SHOWERS MOVING ACROSS THE CWA AROUND 9Z TONIGHT. NOT REAL
SURE WHAT THE FOCUS MECHANISM WILL BE...SO WILL LEAVE TIME PERIOD
DRY FOR NOW.

WITH A SURFACE HIGH PRESSURE EAST OF THE REGION...ALONG WITH UPPER
LEVEL RIDGE BUILDING INTO THE AREA...MOISTURE WILL SURGE NORTHWARD
ON WEDNESDAY. THE SREF SUGGEST A SHORT WAVE TROUGH WILL TRACK
ACROSS THE REGION WITH THUNDERSTORMS EXPECTED. THE TIMING OF THIS
SHORT WAVE IS UNCLEAR AT THIS TIME SO WILL HAVE SCHC TO CHC POPS
DURING THE DAY.

.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
UPPER LEVEL RIDGING WILL BE OVER THE PLAINS WHEN THE PERIOD
STARTS...AND LOOKS TO REMAIN DOMINANT THROUGH THE DAY FRIDAY
BEFORE GETTING PUSHED EAST AS A BROAD UPPER LOW SPINS OVER THE
PACIFIC NORTHWEST...THEN TRACKS TO SOUTH CENTRAL CANADA TOWARD THE
END OF THE LONG TERM. A SERIES OF SHORTWAVES WILL TRACK THROUGH
THE FLOW AND ACROSS THE STATE...WITH NO CLEAR CUT TIME FRAME WHERE
THERE WILL NOT BE ENERGY AFFECTING THE CWA.

AN ELONGATED SURFACE LOW PRESSURE SYSTEM WILL BE OVER THE ROCKIES
WEDNESDAY NIGHT. THE SYSTEM WORKS ITS WAY EASTWARD...THEN BECOMES
NEARLY STATIONARY OVER THE PLAINS BY THURSDAY NIGHT. IN
ASSOCIATION WITH THE UPPER LEVEL SHORTWAVES...THE REGION WILL
REMAIN IN AN UNSETTLED PATTERN...WITH PERIODS OF SHOWERS AND
THUNDERSTORMS THROUGH THE ENTIRE LONG TERM. THE BEST INSTABILITY
LOOKS TO OCCUR FRIDAY AFTERNOON AND EVENING OVER THE ENTIRE
CWA...THEN AGAIN SATURDAY AFTERNOON OVER THE SOUTHEASTERN CWA.
CAPE VALUES IN EXCESS OF 4000 J/KG WITH LIS IN THE -9 TO -13 RANGE
WILL DEVELOP...WITH A FRONTAL BOUNDARY SPRAWLED SOMEWHERE ACROSS
THE CENTRAL OR EASTERN CWA. THE CAP LOOKS TO BE A POTENTIAL
HINDERING FACTOR HOWEVER AS THE CURRENT MODELS ARE SHOWING H7
TEMPS BETWEEN +11 AND +15. EVEN WITH AFTERNOON TEMPS HAVING THE
POTENTIAL TO REACH THE UPPER 80S OR LOWER 90S...THIS CAP MAY BE A
BIT TOO MUCH TO OVERCOME. WILL HAVE TO MONITOR CLOSELY WHEN THE
TIME PERIOD GETS CLOSER.

WILL SEE ABOVE NORMAL TEMPERATURES THROUGHOUT THE PERIOD...WITH
DAYTIME HIGHS MAINLY IN THE 80S. SOME LOCATIONS WILL LIKELY EXCEED
90 DEGREES ON FRIDAY. OVERNIGHT LOWS WILL GENERALLY BE IN THE 60S.

&&

.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

VFR CONDITIONS WILL PREVAIL TONIGHT THROUGH MONDAY. MEANWHILE AN
AREA OF LOW PRESSURE MOVING ACROSS THE ROCKIES COULD PROVIDE
ENOUGH LIFT ALONG A SLOWING COLD FRONTAL BOUNDARY TO TOUCH OFF A
FEW SHOWERS OR ELEVATED THUNDERSTORMS IN OR AROUND KPIR MONDAY
MORNING POSSIBLY INTO EARLY MONDAY AFTERNOON. INTRODUCED SOME
VICINITY SHOWER MENTION FOR NOW.

&&

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

$$
SHORT TERM...SD
LONG TERM...PARKIN
AVIATION...PARKIN

WEATHER.GOV/ABERDEEN