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000
FXUS63 KFSD 230917
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
417 AM CDT THU MAY 23 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT THU MAY 23 2013

LIKELY THE BEST DAY OF THE NEXT MANY DAYS WILL OCCUR ACROSS THE
AREA TODAY WITH SHARP RIDGE ALOFT ACROSS THE AREA. EASTERLY TO
NORTHEAST TRAJECTORY OUT OF KEEWATIN HIGH WILL CONTINUE TO INTRODUCE
DRIER AIR AT LOWER LEVELS.  FLOW IS QUITE ANTICYCLONIC AND OVERALL
LARGER SCALE QUITE SUBSIDENT. RECENT PRECIPITATION HAS SATURATED UP
THE SURFACE QUITE A BIT...AND WITH HEATING AND BUILDING OF MIXED
LAYER WOULD EXPECT POTENTIAL FOR A BIT OF FLAT CUMULUS DEVELOPMENT.
LIKELY SOMEWHAT TERRAIN TIED. LARGE SCALE AND ANTICYCLONIC FLOW
SHOULD KEEP CLOUDS FROM GAINING A GREAT DEAL OF DIURNAL COVERAGE...
PROBABLY AN EARLY TO MID  AFTERNOON MAXIMUM IN THE SCATTERED
COVERAGE REALM. GOOD RECOVERY TO TEMPS WITH SUNSHINE TODAY...
MIXING TO MID 60S TO AROUND 70.

PRESSURE GRADIENT GRADUALLY INCREASES ACROSS THE AREA THROUGH THE
OVERNIGHT AS SURFACE RIDGE RETREATS TO THE EAST. RELATIVELY DRY
AIRMASS ACROSS THE AREA SHOULD LEAD TO COOL OVERNIGHT LOWS...WITH
THE COOLEST READINGS IN THE EASTERN CWA WHERE WINDS AND INCREASING
CLOUDS WILL BE LESS OF A FACTOR.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 340 AM CDT THU MAY 23 2013

MODELS INDICATE STRONG MOISTURE TRANSPORT IN THE MID LEVELS ON
FRIDAY LEADING TO ELEVATED CONVECTIVE POTENTIAL AS ISENTROPIC LIFT
INCREASES THROUGHOUT THE DAY. MODEL SOUNDINGS INDICATE TALL THIN
CAPE PROFILE...AND WITH RELATIVELY WEAK WIND SHEAR...AM NOT
EXPECTING MUCH IN THE WAY OF SEVERE POTENTIAL. BAND APPEARS TO
GRADUALLY SHIFT TO THE EAST FRIDAY NIGHT...WITH CONVECTIVE
POTENTIAL REORGANIZING TO THE SOUTH AS BETTER INSTABILITY AND
MOISTURE ORGANIZES TO THE SOUTH. MODELS INDICATE WARM FRONT
HANGING ACROSS THE AREA THROUGH THE WEEKEND...MAKING CONVECTION
DIFFICULT TO TIME. AM NOT THINKING THE WEEKEND WILL BE AN ENTIRE
WASHOUT...BUT INSTEAD PERIODIC RAIN CHANCES FAVORING A DIURNAL
TREND. SLIGHTLY BETTER SEVERE POTENTIAL EXISTS ON SATURDAY INTO
SUNDAY...HOWEVER...REALTIVELY WEAK WIND SHEAR SHOULD KEEP SEVERE
POTENTIAL FAIRLY ISOLATED. CONVECTION CHANCES APPEAR TO BE FAIRLY
GOOD SATURDAY NIGHT AS LOW LEVEL JET INCREASES ACROSS THE PLAINS
AND HAVE RAISED POPS SOME OVER GUIDANCE.

FORECAST BECOMES QUITE MUDDY BEYOND SATURDAY NIGHT WITH SHORTWAVES
EMBEDDED IN WEST TO SOUTHWEST FLOW ALOFT. MODELS IN GENERAL SUGGEST
AN ACTIVE PATTERN...WITH EACH OFFERING THEIR OWN FLAVOR ON TIMING
AND LOCATION OF POPS. IN GENERAL...KEPT CHANCE POPS THROUGH THE
PERIOD. IN TERMS OF TEMPERATURES...KEPT TEMPERATURES VERY SIMILAR
TO THE PREVIOUS FORECAST...HOWEVER...OPERATIONAL RUN OF GFS IS
ERRING TOWARDS THE WARMER SIDE OF THE ENSEMBLE...POTENTIALLY
SUGGESTING OPTIMISTIC FORECAST HIGHS FOR THE HOLIDAY WEEKEND INTO
EARLY NEXT WEEK.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1023 PM CDT WED MAY 22 2013

VFR CONDITIONS WILL CONTINUE TO PRESS SOUTHWARD ACROSS THE SIOUX
FALLS FORECAST AREA FOR THE REST OF TONIGHT. BEFORE THE
CLEARING HOWEVER...EXPECT WIDESPREAD MVFR TO UPPER END IFR
CEILINGS. IN ADDITION...A SURFACE RIDGE AXIS WILL SETUP EXTENDING
FROM CENTRAL SOUTH DAKOTA TO NORTHEAST SOUTH DAKOTA. BECAUSE OF
THIS...THE WINDS WILL GO PRETTY LIGHT IN OUR NORTHWEST ZONES...
INCLUDING THE KHON TAF SITE...WHICH COULD SETUP SOME MVFR TO IFR
FOG AROUND SUNRISE IN THAT LOCATION OVER THE WET GROUND. THURSDAY
WILL ALSO BE VFR...BUT SOME STRATOCUMULUS CLOUDS COULD FORM IN THE
MIDDLE OF THE DAY CAUSING SOME BROKEN CEILINGS...STILL IN THE
LOWER VFR CATEGORY.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...