Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 121736
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1236 PM CDT FRI SEP 12 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT FRI SEP 12 2014

LIGHT RAIN PERSISTS ACROSS THE SOUTHERN HALF OF THE CWA EARLY THIS
MORNING...AS 600:700 FRONTOGENESIS AXIS SLIDE SE.  RAINFALL AMOUNT
HAVE BEEN AS EXPECTED...WITH MOST AREAS UNDER A HALF INCH.  RAIN
WILL EXIT THE CWA SHORTLY AFTER DAYBREAK...WITH CONSIDERABLE CLOUD
COVER THROUGH THE DAY.  MODEL ARE HINTING AT A BIT OF CLEARING EARLY
EARLY THIS AFTERNOON...AND COULD RULE OUT WIDELY SCATTERED SHOWERS
FORMING AHEAD OF 500 MB TROUGH AXIS THIS AFTERNOON. TEMPERATURES
WILL CONTINUE TO STRUGGLE GIVEN CLOUD COVER...BUT MIGHT REACH THE
MID 50S.

STILL ANTICIPATING A COLD NIGHT TONIGHT AS CLOUD COVER CLEARS FROM
WEST TO EAST. ONCE BACK EDGE OF CLOUD MOVE THROUGH...TEMPERATURES
SHOULD QUICKLY FALL INTO THE 40S AND EVEN 30S GIVEN INVERTED TROUGH
AXIS OVER THE AREA. HOWEVER...AS NOTED IN PREVIOUS
DISCUSSION...WINDS ARE EXPECTED TO TURN SOUTHERLY ACROSS THE WESTERN
HALF OF THE FA WHICH SHOULD PROMOTE LESS OF A DROPOFF IN
TEMPERATURES AFTER MIDNIGHT.  EAST OF THE STATE LINE WINDS SHOULD
REMAIN RATHER VARIABLE...PROMOTING MORE EFFECTIVE COOLING
CONDITIONS.  HOWEVER...LATEST GUIDANCE SUGGESTS THAT DEW POINTS MAY
NOT FALL FAR ENOUGH FOR EFFICIENT WIDESPREAD FROST DEVELOPMENT.
AFTER COORDINATION WITH SURROUNDING OFFICES...WILL HOLD OFF ON ANY
FROST ADVISORY GIVEN CONCERNS ABOUT MIXING...BOUNDARY LAYER
MOISTURE...AND SOIL MOISTURE. IT SHOULD STILL BE A CHILLY NIGHT WITH
TEMPERATURES IN THE MIDDLE 30S.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 315 AM CDT FRI SEP 12 2014

MOST OF THE WEEKEND WILL BE FAIRLY CLEAR WITH A LITTLE BIT OF
WARMING...THOUGH STILL COOL TEMPERATURES. A COUPLE OF WEAK SHORT
WAVES PASS NORTH OF THE AREA IN BROAD UPPER TROUGH AND SHOULD BRING
NO MORE THAN A FEW HIGH CLOUDS. THE NEXT ONE DIVES IN QUICKLY FROM
THE NORTHWEST DURING SUNDAY. BY THAT TIME A HALF DECENT WARM
ADVECTION PATTERN HAS DEVELOPED JUST SOUTH OF THE AREA. WITH
MOISTURE AND WEAK INSTABILITY ADVECTION...AND THE SHORT WAVE TO
PROVIDE SOME LIFT...A FEW SHOWERS SHOULD DEVELOP ACROSS THE AREA
FROM THE WEST BY SUNDAY AFTERNOON AND MAXIMIZE COVERAGE IN THE
SOUTHEAST SUNDAY EVENING. A THUNDERSTORM OR TWO WILL BE POSSIBLE
SOUTH. THIS WAVE IS PRIMED TO EXIT QUICKLY BY MONDAY MORNING AND FOR
NOW WILL CUT OFF THE PRECIPITATION WITH THE NEW DAY...AS SURFACE
HIGH PRESSURE SPREADS IN FROM THE NORTHWEST. A LITTLE REINFORCING
SURGE OF COOL AIR WITH THIS REGIME WILL NOT REALLY CAUSE COOLING
FROM THE WEEKEND. IN ANY EVENT...MONDAY WILL TREND TO BEING A PRETTY
PLEASANT DAY.

THE WHOLE REST OF THE WEEK...TUESDAY THROUGH THURSDAY...WILL SEE
SLOW BUT STEADY UPPER RIDGING AND THE DEVELOPMENT OF A SLOW WARMING
PATTERN. MOISTURE ADVECTION IS LIKELY TO BE SLOW...THE EC ESPECIALLY
SHOWS THIS...AND WITHOUT A DECENT LIFT PROVIDING SYSTEM...WILL KEEP
PRECIPITATION MENTION OUT OF THE FORECAST DURING THIS TIME. THIS IS
USUALLY THE TREND WHEN GETTING INTO THE START OF FALL WHEN IT GETS
HARDER TO BREED SIGNIFICANT CONVECTION WITHOUT A STRONG DYNAMIC
SYSTEM...SUCH AS WE HAD FOR THE 10/4 TORNADO OUTBREAK LAST YEAR.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1233 PM CDT FRI SEP 12 2014
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. ISOLATED INSTABILITY
SHOWERS ACROSS THE AREA WILL QUICKLY FALL APART TONIGHT WITH THE
LOSS OF HEATING. CLEAR SKIES WITH LIGHT WINDS EXPECTED
OVERNIGHT...AND SOUTHERLY WINDS ARE EXPECTED TO INCREASE SATURDAY
MORNING...ESPECIALLY AFTER 15Z.

&&

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

$$

SHORT TERM...DUX
LONG TERM...
AVIATION...


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