Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 160352
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1052 PM CDT WED APR 15 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 405 PM CDT WED APR 15 2015

SCATTERED SHOWERS CONTINUE TO LIFT NORTHWARD IN AREAS EAST OF
INTERSTATE 29 THIS AFTERNOON.  THESE SHOWERS ARE TIED TO A WEAK
SHORTWAVE LIFTING NORTHEAST ALONG THE MISSOURI RIVER VALLEY.
GENERALLY...MODELS HAVE OVERESTIMATED THE IMPACTS OF A DRY LAYER OF
AIR IN THE LOW LVLS...AND SEVERAL SPOTS HAVE RECEIVED MEASURABLE
RAIN THIS AFTERNOON.

INTO THE EVENING HOURS...THE AFOREMENTIONED SHORTWAVE WILL CONTINUE
TO LIFT NORTHWARD.  HRRR/RAP GUIDANCE HANDLING THIS WAVE WITH THE
MOST CONFIDENCE...SUGGESTING A SECONDARY VORT MAX OVER SOUTHWEST
IOWA WILL ROTATE NORTHWARD INTO THE AREA TOWARDS 00Z. TROUGH AXIS
CLEARS THE CWA BY 03Z...WHICH SHOULD PUSH ANY LINGERING SHOWERS NE
OF THE CWA. ANY PRECIPITATION AMOUNTS WILL BE LIGHT...LIKELY ONLY A
TRACE TO A HUNDREDTH.  MOISTURE WILL CONTINUE TO STREAM NORTHWARD
OVERNIGHT...AND WE ARE ALREADY SEEING A FAIRLY SUBSTANTIAL CLOUD
DECK FORM TO THE SOUTH. THIS CLOUD COVER SHOULD BLANKET THE AREA
OVERNIGHT...AND KEEP LOWS FAIRLY BALMY.

WE WILL START OUT THURSDAY DRY...AS SHORT WAVE RIDGING MOVES
OVERHEAD. WEAK ISENTROPIC LIFT WILL TRY TO SPREAD NORTHEAST THROUGH
THE DAYTIME HOURS...AND A FEW SHOWERS COULD BE POSSIBLE ALONG THE MO
RIVER IN THE AFTN.  SOUNDINGS SUGGEST LIMITED INSTABILITY...SO WILL
INCLUDE AN ISOLATED THUNDER MENTION. AFTERNOON MIXING WILL ALLOW
MOST AREAS TO APPROACH THE UPPER 60S.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 405 PM CDT WED APR 15 2015

PRETTY MESSY WOULD DESCRIBE THE OVERALL PATTERN FROM THURSDAY
NIGHT THROUGH SUNDAY...ALL DUE TO THE WANDERING IMPACTS FROM
CLOSED LOW. THE MORE NORTHEAST THE LOCATION...THE SLOWER THE
POTENTIAL ONSET OF PRECIPITATION AS PULSES OF ENERGY ROTATE NORTH
AND NORTHWESTWARD AROUND UPPER LOW WOBBLING AROUND UTAH/COLORADO
THROUGH THE START OF THE WEEKEND. TIE TO THE ORIGINATING NORTHERN
STREAM WAVE WILL CONTINUE TO STRETCH OUT ACROSS THE CWA ON
THURSDAY NIGHT. GRADUALLY WILL SEE THE LOWER CHANCE FOR RAINFALL
DWINDLE BY THE MIDDLE OF THE NIGHT...WITH LOW LEVEL RIDGE DRYING
OUT THINGS A BIT FROM THE NORTH. EVENTUALLY...ANOTHER PULSE OF
ISENTROPIC LIFT WILL PUSH TOWARD THE SOUTH CENTRAL LATE NIGHT AND
FRIDAY MORNING...AND WILL START AT LEAST A LOWER COVERAGE AGAIN.
BETTER DEEPER MOISTURE TOWARD THE SOUTHERN PLAINS WILL GRADUALLY
EDGE NORTHWARD AS LOW PRESSURE ORGANIZES IN THE CENTRAL HIGH
PLAINS...BUT THIS WILL BE A LATER FRIDAY NIGHT TO SATURDAY NIGHT
PERIOD FOR BETTER MOISTURE TRANSPORT INTO THE AREA. BY LATER
SATURDAY AND SUNDAY...NEXT WAVE IN NORTHERN STREAM EXPECTED TO
LINK UP WITH THE CLOSED LOW...LIFTING NORTHWARD AND STARTING THE
MERGING PROCESS. ECMWF IS AT THE MIDDLE TO SLOWER SIDE OF
PROGRESSION AND GENERALLY FOLLOWED FOR PACE OF PROGRESSION. ALSO
QUITE A BIT MORE INTENSE WITH DEVELOPMENT SUNDAY...REALLY CRANKING
UP NORTHWEST WINDS BEHIND THE SYSTEM WITH 50-65 KNOTS AT 850 HPA.
AT THIS POINT A FRINGE SOLUTION...BUT WORTH WATCHING. BEST CHANCE
FOR RAIN APPEARS TO OCCUR LATER SATURDAY INTO EARLY SUNDAY...WITH
TROUGH LIFTING NORTHWARD INTO THE AREA...AND THEN A MORE FRONTAL
ORGANIZATION/SHARPER BACK EDGE TO PRECIPITATION SHIELD WORKING
EASTWARD ON SUNDAY. NOT A GREAT DEGREE OF INSTABILITY...BUT
MARGINAL TO WEAK ENOUGH TO SUGGEST AT LEAST AN ISOLATED THUNDER
THREAT AT TIMES SOUTH OF I 90...AND MAINLY TOWARD THE MISSOURI
RIVER. HARDLY WILL BE A STEADY RAINFALL THREAT SET UP...EVEN
THOUGH FORECAST MAY APPEAR TO BE SO...AS IS NEXT TO IMPOSSIBLE TO
TIME THESE SHORTER TERM INCREASE IN CHANCES AT THIS RANGE.

A COUPLE SMALL AREAS FOR RAIN CHANCES EARLY NEXT WEEK...WITH
SHALLOW WEAK INSTABILITY ACROSS THE EAST MONDAY...AND AMIDST THE
SECONDARY JET ENERGY ON TUESDAY. NEITHER WOULD PLAY OUT TO ANY
DECENT THREAT GIVEN THE FAIRLY BROAD EXTENT OF DRIER AIR IN PLACE.

FOR THOSE WITH EARLY GARDENING INTERESTS SPURRED ON BY THE RECENT
WARM TEMPERATURES...WE WILL LIKELY BE RETURNING TO A FAIRLY
WIDESPREAD THREAT FOR FROST/FREEZING TEMPERATURES BY THE MIDDLE OF
NEXT WEEK. DEEPER MIXING OF COLD TEMPS WOULD SUGGEST HIGHS IN THE
50S SHOULD ALSO BE COMMON NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1049 PM CDT WED APR 15 2015

CEILINGS MY LOWER INTO THE MVFR RANGE OVERNIGHT...THEN IMPROVE
AFTER 15Z ON THURSDAY. LIGHT SHOWERS MAY ALSO DEVELOP THROUGH THE
MISSOURI RIVER CORRIDOR ON THURSDAY...THOUGH MOST OF THIS ACTIVITY
SHOULD STAY TO THE SOUTH AND WEST OF TAF SITES.

&&

.FIRE WEATHER...
ISSUED AT 405 PM CDT WED APR 15 2015

RED FLAG WARNING WILL CONTINUE FOR THE MINNESOTA ZONE INTO SUNSET.
RH AND WINDS HAVE HIT CRITICAL VALUES TODAY AND WILL CONTINUE TO DO
SO UNTIL SLIGHTLY HIGHER SURFACE MOISTURE ARRIVES BY SUNSET.

THURSDAY ACTUALLY LOOKS LIKE A REASONABLE DAY TO BURN.  THE MORNING
CEILINGS COULD BE QUITE LOW...BUT MIXING BY THE AFTERNOON WILL PUSH
MIXING HEIGHTS AOA 3K FT AGL. WINDS WILL BE VERY LIGHT ALL
DAY...AND RH VALUES WILL REMAIN WELL ABOVE CRITICAL LEVELS.

&&

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

$$

SHORT TERM...DUX
LONG TERM...CHAPMAN
AVIATION...JM
FIRE WEATHER...DUX


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