Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 252028
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
328 PM CDT SAT APR 25 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 327 PM CDT SAT APR 25 2015

QUIET WEATHER WILL BE THE RULE THROUGH SUNDAY...WITH SHEARING
DEPARTURE OF UPPER LOW TO SOUTH TOWARD THE OHIO VALLEY...AND
INCREASING INFLUENCE OF NARROW UPPER RIDGE OVER THE NORTHERN PLAINS.
WILL MAINTAIN A DRIER EASTERLY FLOW AS LOW LEVEL RIDGE EXPANDS FROM
WESTERN ONTARIO BACK THROUGH MINNESOTA. DRIER AIR HAS ERODED MOST OF
THE LOWEST CLOUDINESS ALREADY TODAY...REPLACED BY HIGHER MIXING
STRATOCUMULUS FIELD.  MANY OF THESE CLOUDS OVER THE MID AND EASTERN
CWA WILL BECOME FAIRLY PERISHABLE TONIGHT...MAKING FOR A GRADUAL
EAST TO WEST CLEARING WORKING INTO EASTERN SOUTH DAKOTA EARLY
SUNDAY. A BIT MOISTURE TRAJECTORY REMAINS THROUGH THE MISSOURI
VALLEY AND NOT OUT OF THE QUESTION THAT A BIT OF PATCHY FOG COULD
DEVELOP LATE NIGHT...BUT GIVEN THE CONTINUED DRYING AND EASTERLY
GRADIENT...SHOULD NOT BECOME ANY LARGE CONCERN. LOWS IN THE MID 30S
TO LOWER 40S EXPECTED.

THE DRYING AND CLEARING TREND PERSISTS INTO SUNDAY. LITTLE REASON
NOT TO EXPECT THAT IT WILL BECOME MORE DEEPLY MIXED AND LIKEWISE
TOWARD THE DRIER AND WARMER SIDE OF GUIDANCE. WILL HAVE TO WATCH TO
SEE IF RECENT LOCAL WET SPOTS ACROSS SOUTHEAST SOUTH DAKOTA CAN
OVERCOME THIS MIXING...AND KEEP DEWPOINT A BIT HIGHER...BUT AREA OF
HEAVIER PRECIPITATION IS CONSIDERABLY SMALL AND LARGER IMPACT SHOULD
BE MINIMAL.  SHOULD END UP WITH GENERALLY MID TO UPPER 60S.


.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 327 PM CDT SAT APR 25 2015

WEAK UPPER LEVEL RIDGING IS EXPECTED THROUGH THE FIRST HALF OF NEXT
WEEK. WITH TROUGHING BLOCKING FLOW TO THE EAST AND AN UPPER LOW
UNDERCUTTING TO THE SOUTH...FAIRLY PLEASANT WEATHER WILL ABOUND IN
THE NORTHERN PLAINS. WITH THE RIDGE AXIS PARKED OVER THE REGION
MONDAY...EXPECT LIGHT WINDS AND MOSTLY SUNNY SKIES. WHILE MIXING IS
NOT IDEAL...DID TREND WARMER TOWARDS THE BIAS CORRECTED MODELS WITH
HIGHS MAINLY IN THE UPPER 60S AND LOWER 70S. A WAVE SLIDES ACROSS
THE NORTHERN PLAINS TUESDAY BUT LOOKS TO BE QUITE MOISTURE STARVED
AS TREKS THROUGH THE FORECAST AREA. THE NAM AND GFS REMAIN DRY WHILE
THE ECMWF AND GEM PAINT SOME SPOTTY LIGHT RAIN ACROSS OUR NORTHEAST
CORNER. DECIDED TO REMOVE POP MENTION IN TUNE WITH SURROUNDING
OFFICES.

UPPER RIDGE STRENGTHENS OVER THE PLAINS WEDNESDAY AFTERNOON AND
THURSDAY...USHERING IN WARMER WEATHER AND STRONGER SOUTHERLY WINDS.
COULD SEE SOME FIRE DANGER CONCERNS DURING THIS PERIOD BUT THIS WILL
BE DEPENDENT ON HOW MUCH MOISTURE RETURN WILL BE REALIZED. WENT A
BIT PESSIMISTIC ON DEWPOINTS WHICH DROPS OUR RH RIGHT AROUND 30 TO
40 PERCENT. ANOTHER SHORTWAVE APPROACHES AROUND THE FRIDAY OR FRIDAY
NIGHT TIME FRAME. THE ECMWF IS WEAKER AND FASTER WHILE THE GFS
BRINGS IN A MORE ROBUST SLOW MOVING WAVE. THURSDAY AND FRIDAY WILL
SEE HIGHS IMPROVE INTO THE 70S AND 80S.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1250 PM CDT SAT APR 25 2015

MVFR CEILINGS HAVE BACKED INTO THE JAMES VALLEY...AND CONTINUED
LOWER LEVEL DRY AIR ADVECTION AND MIXING WILL CONTINUE TO DRIVE
THESE CLOUDS WESTWARD THROUGH THE NIGHT. THE REMAINDER OF THE
PERIOD SHOULD TURN UP VFR. HOWEVER...SOME UNCERTAINTY TO IF A
LITTLE FOG MAY FORM THROUGH THE MISSOURI AND JAMES RIVER VALLEY
LATER TONIGHT...BUT FOR THE MOST PART SHOULD ONLY BRING A BRIEF
PERIOD OF MVFR TYPE VISIBILITY IF IT DOES DEVELOP.


&&

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

$$

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


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