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000
FXUS63 KFSD 302115
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
315 PM CST SAT NOV 30 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 315 PM CST SAT NOV 30 2013

HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT WITH WINDS RAPIDLY
BECOMING LIGHT AFTER SUNSET. THERE WILL BE A LOT OF BREAKS IN THE
CLOUDS...ESPECIALLY ALONG AND SOUTH OF I90 SO TEMPERATURES COULD
FALL QUICKLY IN THE EARLY EVENING. AS THE HIGH MOVES TO THE EAST
OVERNIGHT AND THE 850 MB THERMAL GRADIENT MOVE INTO ERN SD...CLOUDS
WILL INCREASE ACROSS CENTRAL SD AND INTO PORTIONS OF EASTERN SOUTH
DAKOTA. HOW FAST THESE CLOUDS MOVE IN WILL HAVE A LARGE IMPACT ON
TEMPERATURES. EXPECTING CLOUDS TO REACH KHON BY MIDNIGHT BUT NOT GET
INTO MUCH OF NORTHWEST IOWA UNTIL SUNDAY MORNING. SO HAVE
TEMPERATURES STAY IN THE MID 20S ALONG AND WEST OF THE JAMES RIVER
WITH UPPER TEENS ALONG AND EAST OF I29.

ON SUNDAY...MOST AREAS WILL BECOME OVERCAST AS MID CLOUDS OVERSPREAD
THE REST OF THE AREA BY SUNDAY MORNING. THE SFC RIDGE WILL ALSO BE
OVER MN AND IA MUCH OF THE DAY KEEPING WINDS LIGHT AND LIMITING
MIXING AND RETURN OF WARM AIR AT LOW LEVELS. THIS WILL KEEP
TEMPERATURES 10 DEGREES COOLER THAN TODAY WITH HIGHS IN THE 30S IN
SW MN AND PORTIONS OF NW IA AND EAST CENTRAL SD. WARMEST TEMPERATURES
WILL BE IN THE MISSOURI VALLEY IN THE LOWER TO MID 40S. A WEAK UPPER
WAVE WILL MOVE INTO EASTERN SOUTH DAKOTA SUNDAY AFTERNOON. WHILE THE
UPPER LEVEL FORCING FOR ASCENT IS THERE...THERE IS LITTLE LOW LEVEL
FRONTOGENESIS OR MOISTURE WHICH WILL REALLY LIMIT PRECIPITATION. BUT
WITH THE UPPER WAVE APPROACHING...DID CONTINUE WITH A SLIGHT CHANCE
OF PRECIPITATION. TEMPERATURES WILL BE IN THE MID TO UPPER 30S WITH
UPPER 20S DEW POINTS. THAT WOULD SUGGEST PRIMARILY A RAIN AND SNOW
MIX TRENDING TOWARD ALL SNOW AFTER SUNSET WHEN TEMPERATURES FALL
TOWARD FREEZING.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 315 PM CST SAT NOV 30 2013

THE LIGHT PRECIPITATION...IF IT DEVELOPS TO THE SURFACE...SHOULD
CONTINUE TO DEVELOP EAST SOUTHEAST INTO SOUTHWEST MN AND PART OF
NORTHWEST IA SUNDAY EVENING. AFTER A BRIEF PERIOD OF LOW LEVEL
COOLING AND MIXED RAIN AND SNOW ON THE SOUTHWESTERN EDGE OF THE
PRECIPITATION THREAT AREA...ANY PRECIPITATION SHOULD BE LIGHT
SNOW. MODEL SOUNDINGS ON BUFKIT SHOW CONTINUED MARGINAL
TEMPERATURES ALOFT THROUGH THE EVENING BUT FEEL ANY PRECIPITATION
THAT DOES OCCUR WILL COOL THE AIR ENOUGH TO KEEP IT AS SNOW.
NEVERTHELESS...TEMPERATURES SHOULD LEVEL OFF SUNDAY EVENING AFTER
EARLY COOLING AND MAY RISE A BIT LATER IN THE NIGHT AS A WARMING
PATTERN SLOWLY GETS GOING.

AFTER THIS WAVE SLIDES EAST OF AREA LATE SUNDAY NIGHT...STILL DO
NOT SEE ENOUGH SUPPORT TO MENTION PRECIPITATION FOR MONDAY. THE
WARMING PICKS UP A LITTLE FOR MONDAY AND WITH SOME HEATING THROUGH
AN ASSORTMENT OF HIGHER CLOUDS...MONDAY SHOULD BE MILD WITH HIGHS
IN THE 40S...LOWER 50S SOUTHWEST.

IT WAS GENERALLY AGREED EARLY ON TODAY THAT THE NAM AND GFS ARE
PERFORMING POORLY ON THEIR RAPID ADVANCE OF THE NORTHERN UPPER LOW
AND THE LEADING SURFACE LOW AND FRONT. THE EC AND CANADIAN ARE
CLOSE AND APPEAR MORE CONSISTENT DURING THE LAST DAY OR SO WITH A
DEEPER DIGGING OF THE UPPER TROUGH OVER THE WESTERN USA...AND A
SLOWER ADVANCE OF THE SURFACE LOW AND FRONT. THEREFORE...EXPECT
TUESDAY TO STILL BE MILD...NOT AS WARM AS MONDAY...WITH A CHANCE
TO SLIGHT CHANCE PRECIPITATION THREAT BEING LIGHT RAIN. HAVE
ACTUALLY BEGUN THIS FAR NORTH AS A SLIGHT CHANCE OF RAIN OR
FREEZING RAIN MONDAY NIGHT. STILL DO NOT SEE CONCRETE SUPPORT FOR
PRECIPITATION AS FAR EAST AS OUR AREA...BUT MOISTURE LEVELS DO
INCREASE AND THE FLOW VERY SLOWLY BECOMES MORE FAVORABLE FOR
SCATTERED LIGHT PRECIPITATION AHEAD OF THE FRONT AND LOW.

TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WILL SEE A BETTER CHANCE OF
LIGHT PRECIPITATION ALONG WITH A TURN TO COLDER...WHICH SHOULD
CHANGE ANY PRECIPITATION TO SNOW OVER MOST OF THE AREA BY LATE
WEDNESDAY...EVEN ACCORDING TO THE EC AND CANADIAN. THE PROBLEM IS
THAT OUR FORECAST AREA EVIDENTLY WILL NOT SEE MORE THAT AREAS OF
LIGHT PRECIPITATION DURING THIS TIME AS MEAGER SUPPORT AND
ADVECTION IS REPLACED BY THE STRONG COLD ADVECTION WHICH FAIRLY
QUICKLY INCREASES IN DEPTH. THE BEST CHANCE OF LIGHT SNOW
ACCUMULATIONS APPEARS TO BE IN THE FIRST HOURS AFTER THE AIR
BECOMES COLD ENOUGH FOR SNOW. BUT POPS THROUGH THE PERIOD WILL
STAY AT MOST IN THE CHANCE CATEGORY.

WILL GO WITH THE EXTENDED GUIDANCE AND KEEP POPS BELOW MENTION
THRESHOLD THURSDAY THROUGH SATURDAY...EXCEPT FOR SOME FLURRIES ON
THURSDAY. THE EC WITH ITS SHARPER LARGE SCALE UPPER TROUGH
INDICATES A THREAT OF STEADY LIGHT TO MODERATE SNOW DEVELOPING
RIGHT AFTER THE FORECAST PERIOD...THAT IS NEXT SUNDAY AND MONDAY.
THE OVERNIGHT 06Z GFS HAD A LITTLE SOMETHING LIKE THIS BUT THE 12Z
RUN KEEPS ITS SPEEDY NATURE GOING THROUGH AND BEYOND THE EXTENDED
PERIOD.

AS THE COLD AIR ARRIVES THERE WILL BE SOME WIND...WITH WIND CHILLS
GOING BELOW ZERO LATER THIS WEEK. A SNOW COVER COULD BRING COLDER
TEMPERATURES AND PERHAPS THE NEED FOR A WIND CHILL ADVISORY BY THE
START OF NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1116 AM CST SAT NOV 30 2013

LIGHT WINDS AND VFR CLOUDS AND CIGS EXPECTED THROUGH 18Z AT TAF
LOCATIONS...KFSD...KSUX AND KHON. CIGS WILL BE LOWERING OVERNIGHT
AND INTO SUNDAY MORNING ACROSS SE SD AS WARM FRONT APPROACHES BUT
WITH VERY DRY LOW LEVEL AIR MASS DO NOT EXPECT PRECIPITATION TO
DEVELOP. HOWEVER...CIGS COULD FALL TO AS LOW AS 4000 FT ON SUNDAY
MORNING. OTHER CONCERN IS STRATUS IN THE RED RIVER VALLEY OF ND
AND NW MN. LOW LEVEL TRAJECTORIES BRING THESE CLOUDS INTO THE
MINNESOTA RIVER VALLEY THIS EVENING AND MAY RESULT IN MVFR CIGS AS
FAR WEST AS KMML AND KMWM THIS EVENING BEFORE CLOUDS BEGIN TO MOVE
EAST TOWARD SUNRISE. WINDS THROUGH THE PERIOD WILL BE LESS THAN 10
KTS...FROM THE NORTHWEST THIS AFTERNOON AND EVENING...AND FROM THE
SOUTHEAST ON SUNDAY MORNING.


&&

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

$$

SHORT TERM...SCHUMACHER
LONG TERM...
AVIATION...SCHUMACHER