Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 250743
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
243 AM CDT FRI APR 25 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 243 AM CDT FRI APR 25 2014

NOT A LOT GOING ON IN THE SHORT TERM TODAY AND TONIGHT. A VERY WEAK
MID LEVEL WAVE...FOCUSED NEAR 700MB...WILL PASS ACROSS OUR FORECAST
AREA THROUGH ABOUT 15Z THIS MORNING. THE WAVE WILL SPREAD SOME MID
AND UPPER LEVEL CLOUDINESS THROUGH THE REGION EARLY TODAY BEFORE
DEPARTING. BUT WITH VERY DRY LOW LEVELS...NO RAINFALL WILL OCCUR.
OTHERWISE AT THE SURFACE...WEAK HIGH PRESSURE IS DOMINATING. THE
MIXED DEPTH IS ONCE AGAIN FAIRLY HIGH THIS AFTERNOON. HOWEVER THE
WINDS IN THE MIXED LAYER ARE PROJECTED TO BE LIGHT...THEREFORE
TRANSLATING LIGHT WINDS DOWN TO THE SURFACE DESPITE THE DRY LOW
LEVEL AIR MASS. FOR HIGHS...GENERALLY MIXED DOWN TEMPERATURES FROM
NEAR 800MB WHICH ONCE AGAIN PUTS THE READINGS WITH THE WARMER
GUIDANCE VALUES SUCH AS THE BIAS CORRECTED NUMBERS. TONIGHT...HIGH
PRESSURE BEGINS TO STRENGTHEN SOME TO OUR NORTHEAST...THEN EXTENDS
DOWN THE MS VALLEY LATE TONIGHT. THIS WILL TURN THE SURFACE WINDS TO
AN EASTERLY DIRECTION AND THEY WILL BECOME QUITE BRISK AFTER
MIDNIGHT. THIS COUPLED WITH INCREASING HIGH CLOUDS WILL KEEP OUR LOW
TEMPERATURES MODERATED.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 243 AM CDT FRI APR 25 2014

RICH INSTABILITY AND MOISTURE UPSTAIRS SHOULD NOT QUITE MAKE IT
BEFORE THE END OF SATURDAY...AND WITH SOME COOLING OF THE LOWER
LAYERS AHEAD OF THE ABOVE MENTIONED INFLOW...WILL KEEP A DRY
DAYTIME FORECAST. SOME CLOUD INCREASE WILL BE SLOW MOST OF THE
DAY...BUT MAY PICK UP MID AND LATE AFTERNOON. THE KEY WEATHER
FEATURE FOR THE DAYTIME WILL BE THE EAST SOUTHEAST WINDS WHICH
SHOULD CONTINUE TO PICK UP TO STRONG LEVELS. A WIND ADVISORY COULD
BE CONSIDERED FOR THE AREA BUT CURRENT PROJECTIONS LEAVE WINDS
BARELY SHORT...AND WITH THE NORTHEAST AND SOUTHWEST CORNERS
SLIGHTLY LOWER...SO WILL HOLD OFF ON THIS FORECAST. WITH THE ABOVE
MENTIONED COOLING...HIGH TEMPERATURES WILL BE A LITTLE LOWER THAN
FRIDAY...THOUGH EFFECTIVELY THE PERCEPTION WILL BE MORE THAN
SLIGHTLY COOLER WITH THE WINDY CONDITIONS. HIGHS 60 NORTHEAST TO
LOWER 70S SOUTH SHOULD DO IT.

SATURDAY NIGHT NOW LOOKS TO BRING AN INCREASING THREAT OF
THUNDERSTORMS. SHEAR AND INSTABILITY INDICATE A THREAT OF LARGE HAIL
AND POSSIBLY DAMAGING WINDS WITH SOME STORMS...WITH THE SPC OUTLOOK
ACCEPTED. THE STORMS WILL BE ELEVATED AND NO REAL TORNADO THREAT
SEEN...UNLESS THE LOWER LAYERS WHICH PRESENT A DECENT SHEAR PROFILE
SOMEHOW WARM AND MOISTEN UP MORE THAN PROJECTED. THE HIGHEST POPS
WILL BE IN THE EAST...IN THE PATH OF THE RICH MOISTURE AND
INSTABILITY INCREASE. THERMAL CONTRAST AND DECENT WINDS SHOULD HELP
PROVIDE THE LIFT FOR INITIATION.

SUNDAY WILL BRING A CONTINUED LIKELIHOOD OF SHOWERS AND STORMS AS
THE STRONG SYSTEM MOVES SLOWLY JUST SOUTH OF OUR AREA, FAVORABLE
PARAMETERS SUGGEST A CONTINUED SEVERE THREAT...AT LEAST THROUGH
SUNDAY EVENING....AFTER WHICH UPPER WINDS WILL EB SLOWLY DECREASING
AND THERMAL PROFILES SLOWLY WEAKENING. THE THREAT...AT LEAST OF
GENERAL STORMS...WILL INCREASE WESTWARD OVER THE AREA AROUND THE
LARGE LOW. SURFACE TEMPERATURES WILL BE A LITTLE COOLER YET THAN
SATURDAY BUT STILL SORT OF MILD...AND IT WILL STILL BE UNSTABLE...AT
LEAST DURING THE DAY. SUNDAY NIGHT THEM PRESENTS THE PROSPECT OF
MUCH OF THE AREA BEING DRY SLOTTED AND A LOWERING OF THE HEAVIER
RAIN THREAT LATE.

MONDAY THROUGH WEDNESDAY WILL STILL HAVE THE LINGERING SYSTEM FAIRLY
CLOSE AS IT MOVES VERY SLOWLY TO THE EAST/SOUTHEAST OF THE AREA.
SHOWER/RAIN THREAT WILL CONTINUE WITH SOME LINGERING THUNDERSTORM
CHANCE MONDAY WITH THE SYSTEM STILL IN THE AREA. THE COOLING TREND
WILL BECOME STRONGER AS THE SYSTEM MOVES EAST OF THE AREA. AT THIS
POINT THE LOWER LEVELS LOOK SAFE FROM ENOUGH COOLING TO RESULT IN
LATE SEASON SNOW. EXTENDED GUIDANCE KEEPS SOME CHANCE OF RAIN IN ALL
THE WAY TO THURSDAY NOW AND THIS FITS WITH THE LATEST EC IN
PARTICULAR SO WILL GO WITH THE SMALL POPS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM CDT FRI APR 25 2014

THERE WILL BE SOME PATCHY FOG ALONG AND EAST OF I 29 INTO THE
EARLY MORNING HOURS TODAY...LIKELY INVOLVING SPOTTY LIFR
CONDITIONS. HOWEVER AT THIS TIME...THE FOG POTENTIAL LOOKS TOO
ISOLATED TO MENTION IN THE KFSD AND KSUX TAF SITES...SO LEFT IT
OUT. WILL MONITOR AND UPDATE IF NEEDED. OTHERWISE THE FORECAST
AREA WILL BE VFR THROUGH FRIDAY EVENING WITH LIGHT WINDS...TURNING
TO THE EAST FRIDAY EVENING.


&&

.FIRE WEATHER...
ISSUED AT 243 AM CDT FRI APR 25 2014

STRONG EAST TO SOUTHEAST WINDS...AVERAGING 25 TO 35 MPH WITH SOME
GUSTS UP TO 40 MPH...WILL PREVAIL ON SATURDAY WHICH WILL PRODUCE A
VERY HIGH GRASSLAND FIRE DANGER INDEX. WITH MINIMUM HUMIDITY VALUES
PROJECTED TO REMAIN JUST BELOW 40 PERCENT...RED FLAG CONDITIONS ARE
NOT ANTICIPATED SO A FIRE WEATHER WATCH IS NOT NEEDED AT THIS TIME.

&&

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

$$

SHORT TERM...MJ
LONG TERM...
AVIATION...MJ
FIRE WEATHER...MJ






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