Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 110930
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
430 AM CDT FRI APR 11 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 429 AM CDT FRI APR 11 2014

A PLEASANT DAY AHEAD AS THE WEAK WAVE CURRENTLY SPREADING SPRINKLES
THROUGH THE AREA LEAVES BY SUNRISE. THIS WILL ALLOW FOR MOSTLY SUNNY
CONDITIONS THE MAJORITY OF THE DAY. SOME HIGH LEVEL CLOUDINESS WILL
INCREASE VERY LATE IN THE AFTERNOON AS A WAVE MOVES INTO NORTH
DAKOTA. THIS UPPER LEVEL WAVE MOVE INTO MINNESOTA OVERNIGHT WHICH
WILL BRING AN INCREASE TO LOW AND MID LEVEL WINDS ACROSS THE AREA.
THIS ENHANCED CONVERGENCE COUPLED WITH WEAK INSTABILITY WILL ALLOW
FOR ISOLATED TO SCATTERED SHOWERS TO DEVELOP...MAINLY EAST OF THE
JAMES RIVER VALLEY. LATER IN THE NIGHT SOME SLIGHTLY BETTER
INSTABILITY MAY ALLOW FOR A FEW THUNDERSTORMS OVER FAR SOUTHEAST
SOUTH DAKOTA INTO NORTHWEST IOWA BUT NOT ENOUGH INSTABILITY TO
EXPECT ANY SEVERE WEATHER PROBLEMS. NO MAJOR CHANGES TO HIGHS TODAY
OR LOWS TONIGHT...BOTH BEING VERY MILD AND ABOVE NORMAL.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 429 AM CDT FRI APR 11 2014

SATURDAY WILL PROVE ANOTHER MILD SPRING DAY ACROSS THE AREA...AS
PREFRONTAL WIND SHIFT DRIVES WINDS AROUND TO WEST AND NORTHWEST...
WITH DRYING AND MIXING ALLOWING 70S TO RETURN. NOT ENTHUSIASTIC
ABOUT DAYTIME PRECIPITATION IN GENERAL...WITH THE MORNING ACTIVITY
ALONG WITH WARM FRONTAL BOUNDARY/CONVEYOR SHOWING FAIRLY CAPPED
INSTABILITY EVEN FROM ELEVATED SOURCE...AND THEN ANY LARGER SCALE
SUPPORT WANES WITH WEAK MID LEVEL SHORT WAVE RIDGING THROUGH THE
BULK OF THE DAY. BY LATE DAY...MIXING WILL LIKELY RESULT IN LITTLE
INSTABILITY...EVEN NEARER THE LEADING SURFACE BOUNDARY/MOISTURE
DISCONTINUITY WHICH WILL BE SOUTHEAST OF THE AREA BY EVENING...
AND EVEN VERY LITTLE ALONG THE MAIN COLD FRONT RUSH TO FALL INTO
THE MAIN PRESSURE TROUGH. WILL KEEP SMALL MENTION FOR THUNDER IN
THE LATE AFTERNOON AND EVENING ACROSS THE SOUTHEAST...BUT
OTHERWISE INSTABILITY LOOKS MEAGER.

A FEW STORMS DEVELOPING TO THE SOUTH TOWARD I80 CORRIDOR COULD
THREATEN SEVERITY...AND THE OVERALL UPPER FLOW COULD SEE A LITTLE
BETTER CHANCE FOR ELEVATED STORMS BY LATER IN THE NIGHT CREEP
TOWARD THE FAR SOUTHERN CWA.  MAIN UPPER LEVEL DYNAMICS COME IN
POST FRONTAL LATER SATURDAY NIGHT INTO MIDDAY SUNDAY. NOT TOO
UNSTABLE NEAR FRONTOGENETIC ZONE...AND WILL LIKELY BE BROADER AND
LESS FOCUSED PRECIPITATION. ECMWF A BIT MORE AGGRESSIVE DRIVING IN
LOW LEVEL DRYING AND HAS LESS OVERALL PRECIPITATION...AND EVEN THE
06Z NAM NOW STARTING A SOUTHWARD TREND TO BANDING. HAVE MOST
PRECIP ALONG/SOUTH OF I90 SUNDAY MORNING... AND SINKING SOUTHWARD
THROUGH THE DAY. LOOKS AS IF WILL GET COLD ENOUGH ALOFT TO INTRODUCE
A LITTLE SNOW TO THE NORTHERN/WESTERN CWA AS PRECIPITATION BAND
SLIDES SLOWLY SOUTHWARD. APPEARS AS IF THE WARMER NEAR SURFACE
LAYER WILL MAKE THE DIFFERENCE BETWEEN RAIN AND SNOW...SO FOR NOW
HAVE KEPT THINGS ON THE MIXED SIDE WITH SOME QUESTIONS ON WHETHER
PRECIPITATION RATE WILL BE ABLE TO MAINTAIN A COLD ENOUGH SURFACE
LAYER. LIKELY THAT WILL HAVE PERIODS WITH RAIN/PERIODS WITH SNOW
DURING THE DAY...AND COULD GET A SLOPPY LIGHT ACCUMULATION SOUTH
CENTRAL SD THROUGH SW MN MAINLY THROUGH SUNDAY MORNING...BUT WOULD
NOT REALLY LAST LONG ENOUGH TO MATTER WITH TEMPS EXPECTED TO REACH
NEAR 40 ALMOST EVERYWHERE DURING THE DAYTIME.

EARLY WEEK APPEARS TO BE A DRY PERIOD...BUT TEMPS ALSO SETTLING
BACK TO WELL BELOW NORMAL LEVELS. COLDEST AIR IN AND AROUND MONDAY
NIGHT/EARLY TUE...WITH SOME -10 TO -12C 850 HPA READINGS COMMON
BETWEEN OPERATIONAL SOLUTIONS INTO THE NORTHEAST CWA. LIKELY WILL
HAVE SOME LOWS DIPPING TOWARD 20 DEGREES...AND HIGHS STRUGGLING
TOWARD 40.

VERY LITTLE LARGER SCALE AGREEMENT TO PATTERN BETWEEN TROUGHING/RIDGING
BY MID TO LATE WEEK. SOME VARIATION OFF A MORE ZONAL PATTERN WILL
BE IN ORDER...WITH TEMPS MODERATING A BIT AS WELL BRINGING AS A
PERIODIC PRECIPITATION THREAT. HAVE NOT STRAYED TOO FAR OFF THE
INITIALIZATION VALUES AT THIS POINT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1059 PM CDT THU APR 10 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. HIGH CLOUDS WITH
SOME SCATTERED MID CLOUDS WILL STREAM ACROSS THE AREA OVERNIGHT...BUT
ONLY A FEW SPRINKLES ARE EXPECTED. DAYTIME FRIDAY WILL BE CLEAR WITH
SOME MID AND HIGH CLOUDS STARTING TO RETURN AGAIN AFTER 22Z. RAIN IS
EXPECTED TO HOLD OFF UNTIL AFTER 06Z SATURDAY.


&&

.FIRE WEATHER...
ISSUED AT 429 AM CDT FRI APR 11 2014

FIRE WEATHER CONCERNS WILL AGAIN SURFACE FOR THE NEXT COUPLE OF
DAYS WITH THE PRESENCE OF MILD TEMPERATURES AND LOW HUMIDITY.
WITH DEEPENING OF THE BOUNDARY LAYER THIS AFTERNOON...LOWEST
HUMIDITY SHOULD DIP TO 17 TO 25 PERCENT OVER THE CWA. ANY EARLY
DAY MIXING OF WINDS ACROSS THE NORTHEASTERN HALF OF THE CWA SHOULD
EASE THIS AFTERNOON...WITH SLOWLY INCREASING SOUTHERLY GRADIENT
THROUGH THE FAR WEST. AS A RESULT OF SOMEWHAT DISPARATE WIND AND
HUMIDITY IMPACTS HAVE MAINTAINED A HIGH FIRE DANGER ACROSS THE
ENTIRE AREA FOR THIS AFTERNOON. THEN...ON SATURDAY...AGAIN EXPECT
THAT DEWPOINT FORECAST OF RAW MODELS TO BE SUPERIOR TO STATISTICAL
GUIDANCE...AND EXPECT MOST AREAS WEST OF I29 TO REACH 20 TO 25
PERCENT LOWEST AFTERNOON RELATIVE HUMIDITY. WINDS IN THIS AREA
SHIFTING NORTHWEST AND INCREASING OVER FRIDAY SPEEDS...WHERE HAVE
NUDGED RANGELAND FIRE DANGER TO VERY HIGH. AT THIS TIME...WINDS DO
APPEAR TO NOT BE STRONG ENOUGH TO WARRANT CONCERNS OVER CRITICAL
FIRE BEHAVIOR.

&&

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

$$

SHORT TERM...08
LONG TERM...CHAPMAN
AVIATION...






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