Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 151744
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1244 PM CDT TUE APR 15 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 435 AM CDT TUE APR 15 2014

SOUTHERLY RETURN FLOW WILL DEVELOP THIS MORNING FROM WEST TO EAST AS
THE SURFACE RIDGE SLIPS OFF TO THE EAST. WINDS WILL BECOME BREEZY IN
THE AFTERNOON ACROSS OUR WESTERN HALF...USHERING IN SOME PRETTY
SIGNIFICANT WARM AIR ADVECTION. WITH WEAKER FLOW TO THE EAST OF
INTERSTATE 29 AND SOME RESIDUAL SNOW COVER...TEMPERATURES WILL NOT
WARM NEARLY AS MUCH...BUT IT WILL STILL BE AN IMPROVEMENT FROM
YESTERDAYS READINGS. SKIES WILL START OFF MOSTLY SUNNY...BUT HIGH
AND MID CLOUDS BEGIN BUILDING INTO THE NORTHWEST LATER THIS
MORNING...SPREADING ACROSS THE REMAINDER OF THE FORECAST AREA
THROUGH THE AFTERNOON. HIGHS SHOULD MANAGE TO REACH THE LOW 60S IN
SOUTH CENTRAL SD...BUT ONLY CAP IN THE MID OR UPPER 40S IN SOUTHWEST
MINNESOTA AND PORTIONS OF NORTHWEST IOWA. HIGHS WILL LIKELY OCCUR
RELATIVELY LATE IN THE DAY AS WELL...LIKELY CLOSER TO 6 OR 7 IN THE
EVENING.

BREEZY SOUTHERLY WINDS PERSIST THROUGHOUT THE OVERNIGHT HOURS AHEAD
OF THE APPROACHING WAVE DROPPING OUT OF THE NORTHERN HIGH PLAINS.
SURFACE LOW DEEPENS OVER CENTRAL SOUTH DAKOTA AROUND MIDNIGHT AND
TRACKS INTO OUR WESTERN BORDER LATE TONIGHT. MOSTLY CLOUDY SKIES AND
GUSTY WINDS WILL HELP HOLD TEMPERATURES OVERNIGHT...SO RAISED LOWS A
BIT INTO THE UPPER 30S TO MID 40S. WHILE MID LEVEL MOISTURE
INCREASES OVERNIGHT...DRY LOW LEVELS WILL DELAY THE ONSET OF
MEASURABLE PRECIPITATION FOR MUCH OF THE NIGHT. COULD SEE SOME
SCATTERED SPRINKLES LATE TONIGHT...BUT THE ACTUAL RAINFALL DOES NOT
BEGIN SPREADING INTO OUR NORTHERN AND WESTERN COUNTIES UNTIL CLOSE
TO SUNRISE.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 435 AM CDT TUE APR 15 2014

UNFORTUNATELY...APPEARS THAT ANOTHER MIXED PRECIPITATION SYSTEM WILL
TAKE SHAPE ON WEDNESDAY AS QUICK MOVING JET PUNCHING ON THE
PACIFIC NW COAST THIS MORNING EVOLVES TOWARD A SHARPENING TROUGH
ACROSS THE NORTHERN PLAINS. SHOULD BE QUITE MILD TO START THE DAY
AS SURFACE WAVE SETS UP NEAR THE JAMES VALLEY...AND A STRONG LOW
LEVEL JET SURGES NORTHWARD AHEAD OF FEATURE INTO SW MN. TEMPS
SURFACE AND ALOFT WARM ENOUGH TO HAVE ALL RAIN TO START...BUT COLD
AIR WILL START TO SURGE SOUTHWARD BEHIND THE SYSTEM BY LATER MORNING
INTO THE NORTHWESTERN CWA...AND CONTINUE TO PLOW SOUTHEASTWARD
THROUGH THE DAY. SHARPENING SYSTEM WILL GRADUALLY TEND TO FAVOR A
STRONGER DUAL COUPLET OF QG FORCING...WITH MORE PRECIPITATION IN
WARM ADVECTIVE REGION OF THE FEATURE...AND SOMEWHAT LESS WORKING
INTO WRAP AROUND BAND. A LITTLE MORE PRECIPITATION IS LIKELY TO
OCCUR WITH SOMEWHAT MILDER TEMPS ACROSS THE NORTH IN THE LOWER TO
MID LEVEL FRONTAL BAND...WITH A LIKELY TRANSITION TO SNOW FOR A
TIME BY LATER MORNING AND THROUGH THE AFTERNOON. SOME LOCATIONS
ALONG HIGHWAY 14 FROM BROOKINGS TOWARD MARSHALL SHOULD GET AROUND
AN INCH OF WET SNOW ACCUMULATIONS...MOST PREVALENT ON GRASSY AND
ELEVATED SURFACES. BLUSTERY NORTHERLY WINDS WILL DEVELOP BEHIND THE
SHORT WAVELENGTH SYSTEM WITH VERY STRONG COLD ADVECTION ONCE
AGAIN.ALMOST SEEMS STATISTICAL GUIDANCE IS CLUELESS ON THE
POTENTIAL FOR FALLING TEMPS BEHIND SYSTEM DURING THE DAY...AND
HAVE SIDED MUCH CLOSER TO MORE EXTREME RAW DATA.

BY 00Z...LOCATIONS OTHER THAN THE FAR EAST ARE LIKELY TO HAVE
SCOURED OUT ANY DEEPER MOISTURE...WITH A CONTINUED WRAPPING OF
MOISTURE/STRATUS THROUGH THE REMAINDER OF THE CWA. ONE CONCERN
AFTER THE POTENTIAL FOR SOME LINGERING LIGHT SNOWFALL IN THE FAR
EAST IS THAT TEMPS IN THE INCREASINGLY SHALLOW MOISTURE LAYER
BECOME INSUFFICIENT TO ENSURE ICE CRYSTAL FORMATION. WITH THE
CONTINUED TRAJECTORY OF MOISTURE WRAPPING INTO THE EASTERN CWA
ALONG WITH SHALLOW LIFT...ALMOST APPEARS TO BE A SETUP FOR SOME
DRIZZLE/FREEZING DRIZZLE. ALSO...WITH FLOW WORKING TOWARD AN
EASTERLY COMPONENT OVERNIGHT AND INTO THURSDAY MORNING...EXPECT
THAT ANY LOWER CLOUDS WILL TEND TO BE SOMEWHAT MORE PERSISTENT
THAN MODELS INDICATE.

THURSDAY INTO FRIDAY SOUTHERN STREAM SYSTEM NOW APPEARS TO BE
DISPLACED WELL SOUTH AS THE NORTHERN STREAM KICKS ANOTHER SOMEWHAT
STRONGER WAVE INTO THE REGION THURSDAY NIGHT INTO FRIDAY.
STRUCTURE OF SYSTEM VARIES QUITE A BIT ACROSS THE BOARD
LATITUDNALLY...WITH ECMWF/00Z NAM/CANADIAN GLOBAL FURTHER
NORTHWARD AND GFS/06Z NAM/SREF SOUTHWARD. FORCING FOR LIFT
CONCENTRATED IN LOWER TO MID LEVEL WARM AIR ADVECTION ZONE AS
SECONDARY PV LOBE ROTATES THROUGH THE NORTHERN PLAINS...AND HAVE
INTRODUCED SOME SMALL PRECIPITATION CHANCES ACROSS THE WEST/NORTH
ON THURSDAY NIGHT. UPPER FORCING SEEMS TO ABANDON THE ZONE BY
EARLY ON FRIDAY...SO HAVE NOT CONTINUED POPS. TYPE AGAIN WILL BE
AN ISSUE...AND DANCING A FINE LINE BETWEEN TYPES DEPENDING ON
SOLUTION SET...WITH ANYTHING FROM RAIN TO FREEZING RAIN TO SNOW
NOT OUT OF THE QUESTION. FOR NOW HAVE SETTLED ON A RAIN/SNOW MIX.

SOME MODERATION TO TEMPS WILL BEGIN ON FRIDAY...AND THIS TREND
LOOKS TO CONTINUE HEADING THROUGH THE WEEKEND...AND ESPECIALLY BY
MONDAY. WEEKEND NOW NOT LOOKING AS CLEAN WEATHERWISE WITH WESTERN
TROUGH MOVING INTO THE PLAINS FRIDAY NIGHT THROUGH SATURDAY.
FAIRLY CONVERGENT BOUNDARY WILL PRESS GRADUALLY EASTWARD THROUGH
THE CWA ON SATURDAY AND SATURDAY NIGHT.  INITIAL FORCING WITH
NORTHERN STREAM PORTION OF TROUGH MAY IMPACT THE NORTHERN CWA TO
SOMEWHAT A GREATER DEGREE...WITH SOUTHERN STREAM SYSTEM COMING IN
12-18 HOURS SLOWER LOOKS TO GIVE A STRONGER BOOST TO THE PRECIP
POTENTIAL ACROSS MAINLY NW IA AND ADJACENT LOCATIONS ON SATURDAY
EVENING. INCLUDED POTENTIAL FOR A FEW RUMBLES OF THUNDER ACROSS
EXTREME SOUTHEAST SOUTH DAKOTA...NORTHEAST NEBRASKA...AND
NORTHWEST IOWA SATURDAY AFTERNOON AND EVENING WITH SOME MARGINAL
ELEVATED INSTABILITY. RIDGING SUNDAY INTO MONDAY SHOULD KEEP AREA
DRY AND INCREASINGLY MILD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1230 PM CDT TUE APR 15 2014
VFR CONDITIONS EXPECTED UNTIL WEDNESDAY MORNING. BREEZY SOUTHERLY
WINDS WILL CONTINUE THROUGH THE AFTERNOON AND INTO THE EVENING. AS
THE SURFACE DECOUPLES...STRONG WINDS WILL REMAIN ALOFT AND WILL
HAVE LOW LEVEL WIND SHEAR AT BOTH KFSD AND KSUX. A STRONG COLD FRONT
WILL SURGE SOUTH THROUGH THE AREA WEDNESDAY AM...AND PRECIPITATION
MAY MIX WITH AND TURN TO SNOW NEAR THE HIGHWAY 14 CORRIDOR.
FURTHER TO THE SOUTH...PRECIPITATION SHOULD MAINLY FALL AS
RAIN...WITH LESS VISIBILITY RESTRICTION.


&&

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

$$

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






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