412
FXUS63 KFSD 042018
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
320 PM CDT SAT JUL 4 2009
DISCUSSION
CLOUDS HAVE BECOME MORE CONVECTIVE BASED THIS AFTN...BUT INSTABILITY
RATHER WEAK AND SEEMS TO GET SOMEWHAT CAPPED OFF IN THE MID LVLS...
BUT WILL KEEP AT LEAST ISOLD SHRA MAINLY NERN HLF CWA UNTIL EARLY
EVE. CLOUDINESS WILL LIKELY BREAK UP FM NW TO SE IN CWA THRU EARLY
EVE AS NLY FLOW BRINGS IN DRIER AND MORE STABLE AIR IN FM NORTH.
HOWEVER...BOUNDARY LAYER SHOULD STAY RATHER MOIST WITH RECENT RAINS
AND APPROACHING SFC HIGH RESULTING IN GOOD RADIATIONAL COOLING TNGT.
SO PUT IN PATCHY FOG LATE ESP WRN TO SRN CWA...WHERE BEST DECOUPLING
TAKES PLACE. WILL HAVE TO WATCH FOR SOME MORE WDSPRD FOG IF
CONDITIONS ARE MORE OPTIMUM. /RYRHOLM
FOR NOW WILL GO WITH NO MENTN OF FOG FOR SUN MRNG...BUT IF FOG BCMS
WDSPRD AS MENTND ABV...WE WILL HAVE TO ADD MRNG MENTN. OTRW EXPECT A
FAIRLY SUNNY DAY SUN WITH SOME CUD MAINLY ERN CWA. WK WV SHOWN BY
NAM YSTDY AT THIS TIME FOR LATE SUN LOOKS EVEN WEAKER TDA AND OTHER
MODELS HAVE LTL OR NOTHING...SO WILL CUT SLGT MENTN OF TSTMS NERN
FCST AREA FOR LATE SUN. WITH THE SUN TEMPS SHUD BE WARMER WITH HIGHS
MOSTLY 80-85...OR PRETTY CLOSE TO GUIDNCE.
WE HAVE THE SAME PRBLM WITH A CPL PF VERY WEAK WVS COMING ACRS FOR
MON AND AGN BY LATE TUE...BUT NOT MUCH OTHER SUPPORT AT THIS
TIME...SO WILL KEEP FCST MENTN DRY THRU WED DAYTIME. BEST CHC SEEMS
TO BE ABOUT TUE NGT AS INSTBLTY INCREASES. IN FACT...INCREASE IN
MOISTURE AND INSTLTY MENTND ERY THIS MRNG BY SPC IN INCLUDING THIS
AREA IN DAYS 5/6 SVR OUTLLOK SEEMS TO BE BECOMING A FAIRLY SURE BET.
SO...EVEN WITH CONTD TIMING AND CVRG DIFFICULTIES...THE MOISTURE AND
INSTBLTY INCREASES MAKE TSTM MENTN APPROPRIATE FROM WED NGT ON.
MODELS CONT TO OSCILLATE ON TIMING OF FEATURES BOTH SFC AND ALF.
WHILE DRIER AIR CUD FILTER INTO FSCT AREA LATE IN THE WEEK...FNTL
BOUNDRY CUD ALSO STAGNATE A LTL S OF AREA AND PROVIDE A FVRBL TSTM
ENVIRONMENT. TEMPS WHICH WILL WARM TO DECENT MIDSUMMER NORMALS OR A
TAD WARMER BY MIDWEEK SHUD SLIP BACK A LTL BY THE END OF THE WEEK.
AVIATION
BKN MVFR CIGS SE OF LN FM SPW TO YKN SHOULD BREAK UP TO VFR BY 23Z.
AREAS OF GROUND FOG SHOULD DVLP AFT 08Z...MAINLY FM SERN SD TO NWRN
IA WITH PATCHY IFR VSBYS PSBL THRU 13Z.
.FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
WILLIAMS
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