Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 101151
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
551 AM CST WED FEB 10 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM CST WED FEB 10 2016

WATER VAPOR LOOP EARLY THIS MORNING REVEALS WEAK IMPULSE ZIPPING
SOUTHEAST INTO NORTHERN MINNESOTA...INTERACTING WITH DEEP BAROCLINIC
ZONE ACROSS THE EASTERN DAKOTAS INTO EASTERN NEBRASKA AND WESTERN
IOWA. FAIRLY BROAD BAND OF SNOWFALL IS DEVELOPING RAPIDLY INTO AREAS
BETWEEN INTERSTATE 29 AND THE JAMES VALLEY EARLY THIS MORNING...AND
HIGH RESOLUTION MODELS SEEM RIGHT ON TRACK WITH BOTH TIMING AND
LOCATION OF THE BAND. DEVELOPMENT JUST A BIT QUICKER THAN FORECAST
EARLIER...NO SURPRISE WITH 60-80 KNOTS OF WIND IN MID LEVELS
STREAMING DEVELOPMENT SOUTHWARD...AND QUICKENING THE SATURATION
PROCESS. AS A RESULT OF THE SLIGHTLY QUICKER TIMING...THE BULK OF
THE SNOWFALL WILL OCCUR FROM LATE IN THE CURRENT NIGHT PERIOD
THROUGH THE MORNING HOURS...AS FRONTOGENETIC FORCING INCREASES
THROUGH THE MORNING HOURS. LIFT BECOMES CENTERED IN DENDRITIC GROWTH
RANGE FAIRLY QUICKLY...BUT OVERALL HAS SHORT DURATION TO STRONGER
CORRELATION.  SNOW TO LIQUID RATIOS STILL DO NOT APPEAR TO BE
GREATLY CONCERNING...AS TEMPS WARM JUST ENOUGH TO KEEP MAIN ZONE ON
THE WARMER FRINGE OF DENDRITIC GROWTH ZONE.

STILL HAVE SOME CONCERN WITH LOWER RESOLUTION MODELS CONTINUING TO
INDICATE A SMATTERING OF WEAK INSTABILITY ABOVE THE FRONTAL ZONE...
SUGGESTING THE POTENTIAL THAT BROAD BANDING COULD TRY TO FOCUS A BIT
MORE. FOR NOW...A BROAD BAND OF 1 TO 2 INCHES EXPECTED ALONG AN AXIS
FROM KATY TO KLYV TO KSLB...BUT ANY BANDING COULD PUSH A LOCAL
AMOUNT CLOSER TO 2 TO 3 INCHES. THIS TIME THOUGH...THERE WILL BE
LITTLE WIND TO MOVE THE SNOW AROUND. WESTERN EDGE OF MEASURABLE
SHOULD BE FAIRLY CLOSE TO A KHON TO KSUX LINE.

LARGER SCALE AND DEEPER LIFT FORCING HANGING ON BY ITS TEETH TO THE
SOUTHEASTERN CWA BY EARLY AFTERNOON...WITH INCREASINGLY SHALLOW
MOISTURE PROFILES HANGING ON.  LOSS OF ICE BEARING LAYER COULD
RESULT IN A LITTLE FREEZING DRIZZLE AFTER BAND WANES ACROSS MAINLY
MID JAMES TOWARD EAST CENTRAL SD...AS FURTHER EAST THE LOWER LEVEL
TEMPS REMAIN JUST COOL ENOUGH.

EASTERLY FLOW TONIGHT WILL SPREAD LOWER CLOUDS BACK WESTWARD THROUGH
THE EVENING AND MUCH OF THE OVERNIGHT. SOME FOG LIKELY TO DEVELOP ON
THE WESTERN FRINGE OF THE LOWER CLOUD SHIELD AS WELL. GRADUAL SLIGHT
INCREASE TO WARM ADVECTION ON TOP OF THE MOIST LAYER SUGGEST EVEN A
LITTLE FREEZING DRIZZLE THREAT AGAIN TOWARD SOUTH CENTRAL SOUTH
DAKOTA DURING THE LATTER OVERNIGHT HOURS...BUT DEPTH OF MOISTURE MAY
NOT BE QUITE SUFFICIENT TO PRODUCE A GREAT THREAT.

TEMPERATURES CHALLENGING TODAY AS HAVE NOT BEEN HANDLED WELL UNDER
CLOUD SHIELD THIS MORNING...AND MANY CURRENT READINGS ARE AT OR
ABOVE GUIDANCE HIGHS FOR THE DAY IN THE MID AND EASTERN CWA. HAVE
TRENDED READINGS MUCH WARMER IN THE SHORT TERM...BUT CONTINUED
SHALLOW FEED OF COLD ADVECTION INTO THE EAST AS WELL AS COOLING WITH
PRECIPITATION COULD YIELD A STEADY TO FALLING PERIOD FOR MUCH OF THE
DAY BEFORE RECOVERING AFTER PRECIP DWINDLES. OUT WEST...LIKELY TO FIND
SOME LOWER 40S...ESPECIALLY IF BRIEF CLEARING TREND WHICH APPEARS TO
BE UNDERWAY CAN PERSIST LONG ENOUGH INTO THE DAY.  LOTS OF CLOUDS
TONIGHT BRINGS CONCERNS OF GOING TOO COOL...BUT SHALLOW RIDGE BUILDS
INTO THE EAST...AND MAY GET A PERIOD OF PARTIAL CLEARING AS
BAROCLINICITY COLLAPSES A BIT WESTWARD FOR A TIME...BEFORE HIGHER
CLOUDS RETHICKEN OVERNIGHT. A FEW READINGS NEAR ZERO IN THE FAR
EAST...RANGING UP TOWARD LOWER 20S IN SOUTH CENTRAL SD.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 405 AM CST WED FEB 10 2016

THURSDAY INTO THURSDAY NIGHT WILL SEE A SURGE OF COLD AIR AS A WAVE
POSSES BY. THIS WILL BRING A SMALL CHANCE FOR SNOW TO THE REGION.
FOR NOW NOT REALLY ANTICIPATING MUCH MORE THAN A HALF AN INCH IN
MOST SPOTS. WITH COLD AIR STILL IN PLACE AND WIDESPREAD CLOUD COVER
TEMPERATURES WILL BE ON THE COLDER SIDE...RANGING FROM THE TEENS IN
NORTHWEST IOWA TO NEAR FREEZING IN SOUTH CENTRAL SD. THURSDAY NIGHT
THE COLDER AIR WILL POUR IN AS HIGH PRESSURE BUILDS SOUTH.LOWS
MAINLY TEENS AND A FEW SINGLE DIGITS.

FRIDAY INTO FRIDAY NIGHT WILL BE COLD AS WINDS AVERAGE 10 TO 15 MPH.
THIS WILL KEEP WIND CHILLS BELOW ZERO FOR MOST LOCATIONS MOST OF THE
DAY. HIGHS WILL ONLY REACH 10 TO 15 ABOVE IN MANY SPOTS WITH SOME
MID 20S IN SOUTH CENTRAL SD. FRIDAY NIGHT THE ARCTIC AIR REALLY
TAKES HOLD AND LOWS WILL LIKELY DROP TO 10 BELOW TO 15 BELOW OVER
SOUTHWEST MINNESOTA TO AROUND 5 ABOVE IN SOUTH CENTRAL SD.

IN THE OUTER PERIODS(SATURDAY THROUGH TUESDAY)...COLD TO START THE
PERIOD BUT TRANSITIONING TO ABOVE NORMAL TEMPERATURES BY THE END OF
THE PERIOD. THIS WILL BE IN RESPONSE TO THE STRONG UPPER LEVEL RIDGE
TO THE WEST BREAKING DOWN. A WAVE WILL MOVE ACROSS THE NORTHERN
PLAINS SATURDAY BRINGING A DECENT CHANCE FOR LIGHT SNOW TO THE AREA.
NOT AN EXTREMELY IMPRESSIVE SYSTEM BUT WOULD NOT BE SURPRISED AT A
COUPLE OF INCHES OF SNOW...ESPECIALLY CLOSER TO SOUTHWEST MINNESOTA.
AFTER THIS GENERALLY DRY CONDITIONS THROUGH TUESDAY. WITH WEST
NORTHWEST FLOW ALOFT MID LEVEL TEMPERATURES WILL WARM AND SHOULD BE
SUPPORTIVE OF HIGHS IN THE 30S IN MOST LOCATIONS...WHILE THE
SOUTHWESTERN THIRD OF THE CWA WILL LIKELY SEE SOMETHING CLOSER TO
THE MID FORTIES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 550 AM CST WED FEB 10 2016

BAND OF SNOWFALL ALONG AND EAST OF INTERSTATE 29 WILL CONTAIN MVFR
CEILINGS AND VISIBILITIES THROUGH THE DAY. AS THE PRECIPITATION
WINDS DOWN...FURTHER EXPANSE OF MVFR CEILINGS ARE EXPECTED TO
DEVELOP AND SPREAD WESTWARD THROUGH THE EVENING HOURS. WHILE NOT
MENTIONED IN THE TAF...THERE WOULD BE A LOW PROBABILITY FOR
FREEZING DRIZZLE DURING THE LATER MORNING AND MIDDAY AROUND KHON.

&&

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

$$

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


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