170
FXUS63 KFSD 091606
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1005 AM CST TUE FEB 9 2010
DISCUSSION
CONDITIONS BEGINNING TO IMPROVE ACRS ERN CWA AS SNOW IS TAPERING OFF
TO FLURRIES. VSBYS STILL DROPPING TO 2 TO 4 MILES WITH THE FLURRIES
AND BLOWING SNOW. IF CONDITIONS CONTINUE TO IMPROVE WL PBLY MAKE
ADJUSTENS TO HEADLINES BY 18Z. OTHERWISE...CLOUDS WL CONT TO WRAP
AROUND ERN CWA THIS AFTN WITH CLEARING SPREADING IN FM THE NW. CAA
THRU THE AFTN SO TEMPS WL NOT WARM MUCH FM CURRENT TEMPS.
AVIATION
MVFR CIGS WITH OCNL IFT CIGS THRU 00Z BECOMING VFR.
PREVIOUS DISCUSSION
LOW PRESSURE PRESENTLY CENTERED OVER WESTERN IOWA EARLY THIS
MORNING...WITH LINGERING WRAP AROUND SNOW STREAMING FROM SOUTHERN
MINNESOTA THROUGH THE EASTERN HALF OF OUR CWA. ANY ADDITIONAL
SNOWFALL THROUGH THE MORNING IS EXPECTED BE LIGHT...AROUND A HALF AN
INCH OR LESS. WINDS ARE PRESENTLY BLOWING AROUND 15 TO 25 KTS WITH A
TIGHT GRADIENT ACROSS OUR AREA AS HIGH PRESSURE BUILDS INTO THE
WESTERN HIGH PLAINS...THOUGH EXPECT WIND SPEEDS TO BEGIN TO DROP BY
AFTERNOON UNDER A WEAKENING GRADIENT AS THE LOW PRESSURE CONTINUES
TO MOVE AWAY FROM THE AREA. TEMPERATURES HAVE RESPONDED AS EXPECTED
OVERNIGHT AS WARMER AIR WRAPPED WESTWARD AROUND THE SYSTEM...WITH
RISING TEMPERATURES OCCURRING FROM NORTH TO SOUTH OVERNIGHT. BECAUSE
OF THIS...THE DIURNAL TREND IS RATHER TRICKY THROUGH THE EARLY PART
OF THE DAY...WITH TEMPERATURES CONTINUING TO RISE OVER OUR SOUTHEAST
THROUGH THE MORNING...WHILE FALLING BACK SOME IN OUR NORTHWEST
EARLY...BEFORE READINGS ACROSS THE CWA BEGIN TO STEADY OUT OR RISE
SLIGHTLY DURING THE AFTERNOON.
IN TERMS OF HIGHLIGHTS...CANCELLED ALL ADVISORIES THAT WERE IN PLACE
FROM THE INTERSTATE 29 CORRIDOR WESTWARD...WHERE LITTLE SNOW FELL
AND WINDS ARE EXPECTED TO DECREASE FIRST. IN COORDINATION WITH
SURROUNDING OFFICES...KEPT THE WINTER WEATHER ADVISORY THROUGH THIS
AFTERNOON OVER OUR SOUTHWESTERN MINNESOTA AND NORTHWESTERN IOWA
ZONES...IN CONSIDERATION OF SLIGHTLY HIGHER SNOWFALL AMOUNTS IN THAT
AREA...AND A LONGER DURATION OF HIGHER WIND SPEEDS THROUGH THE DAY.
EVEN SO...THINK IT IS PRETTY MARGINAL WITH WIDESPREAD ONE HALF MILE
VISIBILITIES UNLIKELY...BUT COULD MEET THOSE CONDITIONS ON A LOCAL
SCALE. IF WINDS FALL OFF QUICKER THAN FORECASTED...DAY SHIFT MAY
ELECT TO SHORTEN OR CANCEL THE ADVISORY.
THE HIGH PRESSURE WILL CONTINUE TO BUILD INTO OUR REGION
TONIGHT...WITH THE RIDGE AXIS LOCATED RIGHT OVER OUR CWA BY
WEDNESDAY MORNING. THIS WILL ALLOW SKIES TO CLEAR OUT...AND WITH
THE VERY LIGHT WINDS UNDER THE HIGH...TEMPERATURES WILL PLUMMET
TONIGHT WITH FRESH SNOW OVER MANY AREAS. WENT BELOW GUIDANCE AND
HAVE LOWS GENERALLY FROM AROUND 5 BELOW TO AROUND 10 BELOW.
SURFACE RIDGING PUSHES TO THE EAST ON WEDNESDAY AND
THURSDAY...PUTTING OUR AREA BACK INTO A RETURNING SOUTHERLY FLOW.
THIS WILL ALLOW TEMPERATURES TO WARM A BIT EACH DAY...IN THE TEENS
DURING THE DAY ON WEDNESDAY AND INTO THE 20S ON THURSDAY. MODELS
PROGGING VARIOUS WEAK SHORTWAVES EMBEDDED IN A NORTHWESTERLY UPPER
LEVEL FLOW TOWARD THE END OF THE WEEK...THOUGH DIFFERING A BIT ON
TIMING WITH THESE FEATURES. DID THROW IN SOME SLIGHT POPS FOR
THURSDAY NIGHT AND FRIDAY IN OUR EAST...WITH SOME CONSENSUS FOR THE
PASSAGE OF A WAVE OVER OUR AREA DURING THAT TIME FRAME. WILL
CONTINUE TO SEE SLIGHT WARMING ON FRIDAY...UP INTO THE MID AND UPPER
20S OVER MOST OF THE CWA. /JM
FSD WATCHES/WARNINGS/ADVISORIES
IA...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR IAZ002-
003-013-014-021-022-032.
MN...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR MNZ071-
072-080-081-089-090-097.
NE...NONE.
SD...NONE.
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