Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 192327
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
627 PM CDT SAT JUL 19 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 303 PM CDT SAT JUL 19 2014

LINGERING CLOUD COVER OUT THERE THIS AFTERNOON...SOME CIRRUS
ASSOCIATED WITH DYING CONVECTION AND SOME STRATOCU WITH MOISTURE
STUCK BELOW THE STRONG INVERSION ALOFT. THESE CLOUDS SHOULD
DISSIPATE TONIGHT...GIVING WAY TO MOSTLY CLEAR SKIES. THE LOW LEVEL
JET WILL INCREASE AGAIN TONIGHT WITH A BOUNDARY MAKING ITS WAY
TOWARDS THE CWA AS WELL. APPEARS TO BE TOO MUCH OF A CAP TO GET ANY
ELEVATED CONVECTION FOR MOST OF THE AREA...AND THUS CUT BACK ON POPS
FOR LATE TONIGHT AND EARLY TOMORROW. HI RES GUIDANCE HAS ALSO BACKED
OFF ON CONVECTION CHANCES...AND THEY DID A PRETTY GOOD JOB WITH THIS
MORNINGS ACTIVITY. WILL HOWEVER KEEP A SLIGHT CHANCE OF A
THUNDERSTORM ALONG THE HIGHWAY 14 CORRIDOR...WHERE SLIGHTLY BETTER
CONVERGENCE AND COOLER TEMPS ALOFT MAY ALLOW FOR AN ISOLATED
STORM LATE TONIGHT OR EARLY TOMORROW. EXPECT A MILD NIGHT
WITH LOWS IN THE MID 60S TO AROUND 70.

STORY FOR TOMORROW WILL BE INCREASING HEAT AND HUMIDITY. SKIES
SHOULD END UP MOSTLY SUNNY. COULD BE A BIT OF CIRRUS AND
STRATOCU...BUT MODEL SOUNDINGS SUGGEST BOTH OF THESE WILL BE LESS
EXTENSIVE THAN TODAY. BIAS CORRECTED GUIDANCE HAS BEEN PERFORMING
PRETTY WELL WITH TEMPERATURES AND DEWPOINTS...AND FOLLOWED IT
CLOSELY FOR TOMORROW. THIS GIVES MID AND UPPER 80S ALONG AND EAST OF
INTERSTATE 29...WITH 90S TO THE WEST. IT WILL BE QUITE UNCOMFORTABLE
WITH DEWPOINTS LIKELY INCREASING INTO THE LOW 70S EAST OF THE JAMES
RIVER. WITH THE HIGH DEWPOINTS HEAT INDICES SHOULD BE IN THE UPPER
80S TO MID 90S ALONG AND EAST OF INTERSTATE 29...ALTHOUGH THIS HIGH
MOISTURE WILL LIMIT MIXING AND KEEP TEMPS LOW ENOUGH TO PREVENT HEAT
ADVISORY CRITERIA. MEANWHILE IN CENTRAL SOUTH DAKOTA...EXPECT BETTER
MIXING AND HIGHS IN THE UPPER 90S...ALTHOUGH WITH DRIER AIR MIXED TO
THE SURFACE...HEAT INDICES SHOULD AGAIN STAY BELOW 100. HOWEVER
THERE IS A NARROW AREA...ROUGHLY BETWEEN THE MISSOURI RIVER AND
JAMES RIVER...WHERE MOST OF THE RAW AND BIAS CORRECTED GUIDANCE ARE
SUGGESTING 100 TO 102 HEAT INDICES DURING THE AFTERNOON HOURS. GIVEN
THE MARGINAL EVENT...WILL HOLD OFF ON A HEAT ADVISORY AT THIS TIME
AND LET OVERNIGHT SHIFT TAKE ANOTHER LOOK AT THINGS. EITHER WAY IT
WILL BE A HOT AND HUMID ONE OUT THERE TOMORROW.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 303 PM CDT SAT JUL 19 2014

SUNDAY NIGHT AND MONDAY...AS THE HEAT AND HUMIDITY BUILD UP CLOSE TO
HAZARDOUS LEVELS...IS LOOKING PRETTY CAPPED. WITHOUT A PROJECTED
HALF DECENT LLJ...BOTH PERIODS SHOULD BE RAIN FREE. MEANWHILE...
THOUGH THERE WILL BE A FEW CLOUDS...THE HEAT INDEX WILL BE GOING
ABOVE 100 AND CLOSE TO 105 IN PLACES. AROUND 105 IS THE STARTING
POINT FOR AN EXCESSIVE HEAT WATCH SO THIS IS ON THE FENCE AS WELL.
AFTER COORDINATION HAVE DECIDED TO HOLD OFF.

A COLD FRONT... NOT REALLY BACK DOOR...BUT WILL CALL IT A SIDE DOOR
SINCE IT RESULTS PARTLY FROM THE UPPER RIDGE BRIEFLY REBUILDING WELL
WEST OF THE AREA...SHOULD MAKE IT SOUTH THROUGH THE AREA LATE MONDAY
NIGHT AND EARLY TUESDAY. THIS IS A FEW HOURS SLOWER THAN WE HAD
EARLIER BEEN GOING FOR. STILL...AN INCREASE IN CLOUDS AND THE START
OF A COOLER LOW LEVEL FLOW DURING THE DAY SHOULD KEEP THE HEAT OUT
OF THE HIGHLIGHT RANGE...EVEN THOUGH THE MORNING WILL STILL BE QUITE
STICKY. THE FRONTAL BOUNDARY AND SOME INCREASE IN LOWER LEVEL WINDS
WILL BEING A CHANCE OF STORMS TO THE AREA BUT COVERAGE IS NOT
EXPECTED TO BE GREAT DUE TO MARGINAL UPPER SUPPORT AND INSTABILITY
NOT MATCHING UP WELL WITH THE BEST WIND AND THERMAL SUPPORT OVER OUR
AREA. TEMPERATURES TUESDAY WILL BE SLIGHTLY LESS HOT WITH A TREND
FOR HUMIDITY TO GET A TAD LOWER AS THE COOLER AIR STARTS TO SEEP
IN.

TUESDAY NIGHT AND WEDNESDAY SHOULD BE DRY AND COOLER AFTER A LITTLE
CHANCE OF LINGERING EVENING STORMS EARLY TUESDAY EVENING FAR EAST.
TEMPERATURES SHOULD STILL BE DECENT...A FEW DEGREES BELOW NORMAL
THURSDAY. WILL GO WITH THE EXTENDED GUIDANCE SMALL CHANCE OF STORMS
WEST/SOUTHWEST BY THURSDAY...BUT IT APPEARS THE BEST CHANCE WILL
HOLD OFF UNTIL THURSDAY NIGHT AND FRIDAY WHEN A STRONGER COLD FRONT
ASSOCIATED WITH A PROGRESSIVE RIDGE BUSTING TROUGH COMES ACROSS THE
AREA. SATURDAY SHOULD THEN BE DRY AND RELATIVELY COOL.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 626 PM CDT SAT JUL 19 2014

A BULK...IF NOT ALL...OF THE TAF PERIOD IS EXPECTED TO REMAIN VFR.
AREAS OF MVFR CEILINGS ACROSS SOUTHWEST MINNESOTA WILL ERODE EARLY
THIS EVENING. AGAIN WILL HAVE POSSIBILITY OF AN ISOLATED
THUNDERSTORM LATE NIGHT AND EARLY MORNING FOR KHON...BUT FAR BELOW
MENTIONABLE CERTAINTY. ANY ISOLATED STORMS WOULD BE CAPABLE OF A
BRIEF MVFR VISIBILITY OR CEILING.  LIKELY THAT SOUTHERLY WINDS
WILL INCREASE SOMEWHAT AGAIN ON SUNDAY... WITH GUSTS NEAR OR ABOVE
25 KNOTS AT TIMES NEAR AND EAST OF INTERSTATE 29. SOME DIURNALLY
FAVORED STRATOCUMULUS DEVELOPMENT IS AGAIN LIKELY WITH MOISTURE
TRAPPED BELOW INVERSION...BUT COVERAGE SHOULD BE LESS THAN SATURDAY.

&&

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

$$

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






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