000
FXUS63 KFSD 080436
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1036 PM CST FRI MAR 7 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 358 PM CST FRI MAR 7 2014

ANY LINGERING LIGHT PRECIPITATION IN OUR SOUTHERN AREAS...MAINLY
LIGHT SNOW IF ANYTHING BY LATE AFTERNOON...WILL EXIT THE CWA BY
02Z-03Z AS MID LEVEL WAVE PUSHES SOUTH. THIS SHOULD LEAVE US WITH
DRY CONDITIONS THROUGH THE REMAINDER OF TONIGHT THROUGH SATURDAY AS
HIGH PRESSURE MOVES INTO THE REGION. CLOUDS WILL BE A LITTLE SLOWER
TO DECREASE...BUT DO EXPECT MAINLY CLEAR SKIES BY DAYBREAK WITH LOWS
IN THE SINGLE DIGITS TO LOWER TEENS. GUSTY NORTH WINDS WILL LIKEWISE
SLOWLY DECREASE THROUGH THE EVENING...BECOMING LIGHT AND VARIABLE BY
SATURDAY MORNING.

WILL STILL BE DEALING WITH THE EFFECT OF SNOW COVER ON TEMPERATURES
TOMORROW...ALONG WITH LIMITED MIXING WITHIN THE SURFACE RIDGE AS IT
WORKS EAST ACROSS THE CWA. THESE TWO FACTORS SHOULD COMBINE TO KEEP
CENTRAL AND EASTERN PORTIONS OF THE AREA IN THE 20S...WHILE AREAS
WEST OF THE JAMES RIVER WARM INTO THE 30S AIDED BY MINIMAL SNOW
COVER AND LIGHT SOUTHWEST FLOW BEHIND THE RIDGE.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 358 PM CST FRI MAR 7 2014

THE TREND INTO WARMER TEMPS WILL START ON SATURDAY NIGHT...WITH
STRONG WARM AIR ADVECTION EVOLVING ACROSS THE CWA.  NOT TOO
CONCERNED WITH STRATUS AT THIS TIME GIVEN THE DEEPER WESTERLY
COMPONENT...BUT WILL HAVE TO KEEP AN EYE ON THE POTENTIAL ONCE
START INJECTING MORE SNOW MELT MOISTURE BELOW THE DEVELOPING
INVERSION. TEMPS WILL SHOW AN EVENING FALL...THEN A PRETTY STOUT
RISE WITH STRONG WESTERLY COMPONENT TO WINDS ALOFT. RISES AS MUCH
AT 12 TO 15C AROUND 900 HPA OVERNIGHT...WHICH WILL BE MORE
REALIZED AT HIGHER ELEVATION SITES. OTHER ISSUE WITH THE OVERNIGHT
AND EARLY SUNDAY CONDITIONS IS STRONG WINDS AGAIN FOR THE BUFFALO
RIDGE AND DOWNSTREAM. POTENTIAL FOR AROUND 30 KNOT WEST SOUTHWEST
GUSTS LATER NIGHT AND EARLY SUNDAY MORNING GIVEN INVERSION
STRENGTH...REVERSE SHEAR...AND FLOW DIRECTION.

THE ONLY REAL ISSUE WITH WARMING ON SUNDAY IS THE SNOWCOVER...
WHICH WILL BE PRETTY MUCH IN THE STATE IT IS TODAY. ALSO...FACTOR
IN THE TERRIBLY STRONG INVERSION CREATED BY WARMING OF TEMPS ALOFT
BY 8-12 DEGREES C IN THE PREVIOUS OVERNIGHT. WILL ALSO BE AT LEAST
A LITTLE CIRRUS IN THE MIX...AND ALL SAYS WOULD NOT BE WISE TO
TAKE TEMPERATURES TO THE MAX WARMING POTENTIAL FOR AT LEAST THE
NORTHEAST HALF OF THE AREA. USING LOCAL SNOW CLIMATOLOGY...
GENERALLY WENT FROM JUST BELOW ABOUT MID WAY BETWEEN AVERAGE AND
RECORD TEMPS FOR 6+ INCHES SNOWCOVER FOR DEEPER SNOWCOVERED AREAS
OF SOUTHWEST MINNESOTA...TO A FULL 925 HPA MIXING INTO THE LOWER 60S
FOR LOWER BRULE LOCATIONS.

A LITTLE ENERGY CROSSES THE LARGER SCALE RIDGE AND SLIDES DOWN
THROUGH THE AREA LATER SUNDAY NIGHT AND MONDAY...AND WILL DRIVE A
LITTLE BACK DOOR BOUNDARY SOUTHWARD THROUGH MONDAY. OVERALL...PROBABLY
MORE MECHANICAL ON MONDAY...AND BETTER MIXED WITH SOME COOLING OF
THE WARMEST TEMPS ALOFT...BUT WILL ALSO HAVE INCREASE IN CLOUDS
AND A GRADUAL FILTERING OF COOLER AIR SOUTHWARD THROUGH THE DAY.
HAVE TEMPS GENERALLY FROM MID 40S NORTHEAST TO AROUND 60 MISSOURI
VALLEY...THE LATTER READINGS AGAIN FORECASTING A LITTLE SHY OF
FULL MIXING OF WARMEST POTENTIAL.

MOST INTERESTING PART OF THE LONGER RANGE SETS IN MONDAY NIGHT AND
TUESDAY. A FAIRLY STRONG DEFORMATION ZONE EVOLVES ACROSS THE AREA
MONDAY NIGHT INTO TUESDAY. TEMPERATURES IN THE COLUMN ALSO SUGGEST
THAT WILL BE LIKELY DEALING WITH A MIX THEN CHANGE TO SNOW...
ESPECIALLY WITH THE STRENGTH OF FRONTOGENETIC FORCING AND THE
INSTABILITY POISED TO THE SOUTH OF/ABOVE THE BOUNDARY. FORTUNATELY...
APPEARS THAT WILL BE SOMEWHAT PROGRESSIVE WITH BEST FRONTAL FORCING
SINKING FAIRLY STEADILY SOUTHEAST THROUGH THE LATTER NIGHT AND
TUESDAY. VERY CERTAIN THERE WILL BE PRECIPITATION GIVEN THE DYNAMIC
SET UP...WITH LACK OF CATEGORICAL POPS DUE MORE TO TIMING AT THIS
POINT. SHOULD BE A FAIRLY DISTINCT BAND OF RAIN CHANGING TO SNOW...
AND SOME ACCUMULATION OF SNOW WOULD BE EXPECTED.

TEMPS TUESDAY WILL BE WARMEST FOR MOST LOCATIONS EARLY IN THE DAY
WITH NORTHERLY FLOW AND CLOUDS...ALONG WITH LIKELY RAIN/SNOWFALL...
PUTTING DAMPER ON DAYTIME MODERATION. COOLER BUT NOT TOO COLD FOR
TUESDAY NIGHT WITH GRADUAL CLEARING AND WINDS EASING. ON WEDNESDAY...
ASSUMED WILL HAVE TO WORK ON MELTING A LITTLE NEW SNOW...AND DID
NUDGE READINGS JUST A BIT DOWN FROM EARLIER READINGS.

BY THURSDAY AND FRIDAY...RETURN TO A WARMER PATTERN AND WILL SEE
HIGHS RETURN TO 40S AND 50S...WITH DRY CONDITIONS EXPECTED.
ANOTHER BOUNDARY LURKS JUST BEYOND THE PERIOD...WHICH LOOKS TO
CONTAIN THE NEXT CHANCE FOR PRECIPITATION.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1032 PM CST FRI MAR 7 2014

BITS AND PIECES OF MVFR STRATUS STILL FLOATING AROUND THE AREA.
ONE AREA WAS IN THE WESTERN CWA...WHICH WAS SLOWLY DRIFTING WEST
AND THE OTHER WAS IN THE FAR EASTERN CWA WHICH WAS DRIFTING
SOUTHWEST BUT FALLING APART A BIT. SO...THINKING MAINLY VFR
THROUGH THE PERIOD BUT DO SUSPECT THERE WILL BE A FEW PERIODS OF
MVFR EARLY IN THE PERIOD. DRIER AIR ADVECTING IN FROM THE NORTH
MAY HELP CONTINUE THE EROSION OF THIS STRATUS BUT THE NEXT FEW
HOURS IT IS LIKELY TO BE IN AND OUT.

&&

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

$$

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