Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 230958
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
358 AM CST SUN NOV 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CST SUN NOV 23 2014

VERY MILD AIR REMOVES ANY THOUGHT OF PRECIPITATION TYPE OTHER
THAN RAIN WITH FRONTAL/POSTFRONTAL BAND MOVING EAST THIS MORNING
AND EARLY AFTERNOON. COOLING WILL NOT BE ENOUGH FOR SNOW OR ANY
OTHER WINTER PRECIPITATION UNTIL THIS BAND MOVES EAST/SOUTHEAST
OF THE AREA. RAINFALL AMOUNTS TODAY WILL BE QUITE LIGHT. TEMPORARY
PARTIAL CLEARING WILL TAKE PLACE AHEAD OF LOWER CLOUDS SPREADING IN
FROM THE NORTH/NORTHWEST LATE IN THE DAY.

HIGH TEMPERATURES WILL BE REACHED THIS MORNING IN MOST AREAS WITH
SOME MARGINAL EARLY AFTERNOON HIGHS MAINLY WEST WHERE THE WARMEST
AIR DID NOT REACH.

STRONG NORTHWEST WINDS WILL DEVELOP BEHIND THE FRONT BY THIS
AFTERNOON. WINDS SHOULD REACH ADVISORY CRITERIA WEST...AND WILL GO
WITH A WIND ADVISORY THERE FOR THE AFTERNOON AND EARLY EVENING.
WINDS ARE NOT EXPECTED TO QUITE REACH ADVISORY LEVELS EAST TODAY AND
THIS EVENING...AND WINDS WEST SHOULD DECREASE SLIGHTLY TONIGHT.

TONIGHT WILL BRING THE LOW CLOUDS CONTINUING TO MOVE OVER THE AREA.
SOME LOW BASED LIGHT SNOW WITH THESE CLOUDS WILL BE MINIMAL ON
AMOUNTS WITH NO REAL MID LEVEL SUPPORT OR MOISTURE...BUT THERE IS
ENOUGH SUPPORT TO INCLUDE POPS FOR MINIMALLY MEASURABLE
PRECIPITATION. AM NOT ANTICIPATING ENOUGH SNOW FOR BLOWING SNOW...
WHATEVER THE WINDS. WINDS MAY PICK UP AGAIN LATE TONIGHT EAST AS A
SECONDARY SURGE OF COLD AIR SPREADS IN. TEMPERATURES WILL DROP INTO
THE TEENS TO LOWER 20S BY EARLY MONDAY MORNING. WIND CHILLS WILL
DROP TO WITHIN A FEW DEGREES OF ZERO...ON THE MINUS SIDE NORTH OF
INTERSTATE 90 AND ON THE PLUS SIDE SOUTH.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 357 AM CST SUN NOV 23 2014

AS MAJOR CYCLOGENESIS CONTINUES ACROSS THE WESTERN GREAT LAKES ON
MONDAY...WILL BE JUST A BIT TOO FAR AWAY TO TRULY HAVE MUCH OF AN
IMPACT ON THE AREA...BESIDES THE WIND. MID MIXED LAYER WINDS OF 32
TO 34 KNOTS ARE SUGGESTIVE THAT AT LEAST THE EASTERN THIRD OF THE
AREA WILL LIKELY NEED A WIND ADVISORY STARTING EARLY MONDAY MORNING
AND CONTINUING THROUGH THE DAYLIGHT HOURS. WILL LET THIS AREA BE
FULLY DEFINED BY LATER SHIFTS...BUT WILL HAVE WINDS IN THE GRIDS
SUGGESTIVE OF THE NEED. AS FAR AS PRECIPITATION GOES...FAIL TO SEE
MUCH TO THINK ANYTHING NEAR WIDESPREAD MEASURABLE PRECIPITATION IS
EXPECTED...AND FOR THE MOST PART WOULD PROBABLY BE BEST COVERED BY
OCCASIONAL FLURRIES AS TEMPS FALL INTO THE DENDRITIC...AND SHALLOW
CONVECTIVE STREETS IN THE CYCLONIC FLOW TAKE OVER. SOME AREAS
TOWARD THE NORTHEASTERN SD GLACIAL HILLS AND BUFFALO RIDGE WOULD
BE A BIT MORE FAVORED TO GET SOME MORE PERSISTENT LOCALIZED
CONVERGENCE AND PERHAPS A MORE COHERENT SHALLOW SNOWBAND DEVELOPED
WHICH WOULD STREAM SOUTHEAST. WITH THE WIND...WILL BE HARD PRESSED
TO FIND ANY LOCATION THAT WILL LIKELY BE ABLE TO MEASURE
SNOWFALL...SO FOR NOW THE STRATEGY WILL BE TO DOWNPLAY THE
SNOWFALL OUTSIDE THE NORTHEASTERN CWA IN LIEU OF FLURRIES.

NOTE INCREASE IN LOWER LEVEL RELATIVE HUMIDITY ALONG EASTWARD
ADVANCING THERMAL GRADIENT LATER MONDAY NIGHT INTO TUESDAY
MORNING. THERE IS A VERY SUBTLE WAVE PUSHING SOUTHEASTWARD WITH
SMALL PULSE OF DIV Q AND SLIGHT DEEPENING OF THE MOIST LAYER.
NOT IMPOSSIBLE THAT COULD GET A FEW FLURRIES IN WARM AIR ADVECTIVE
ZONE DURING THE VERY LATE NIGHT/EARLY MORNING ACROSS SOUTHEAST
SOUTH DAKOTA. WILL EVEN NEED TO KEEP AN EYE ON SATURATION DEPTH...
AS THERE IS SOME POSSIBILITY OF LACK OF ICE FORMATION WHICH COULD
BRING SOME FREEZING DRIZZLE INTO THE EQUATION. OTHERWISE...A
PARTLY TO MOSTLY CLOUDY DAY EXPECTED ACROSS THE AREA ON TUESDAY AS
TEMPERATURES ATTEMPT TO MODERATE WITH SOUTHERLY FLOW INCREASING
AHEAD OF STRONGER CLIPPER WAVE PUSHING INTO THE NORTHERN PLAINS
DURING THE AFTERNOON. STRONGER WARM AIR ADVECTION COULD BRING A
FEW LIGHT RAIN/SNOW SHOWERS TO THE FAR NORTHWEST...WITH LIMITED
MOISTURE LIMITING POPS AT THIS TIME TO SLIGHT CHANCE.

TUESDAY NIGHT...REJECTED THE OUTLIER GFS...AND WENT WITH STRONG
CONSENSUS OF STRONG CLIPPER TRACKING NORTH OF THE CWA. THIS
USUALLY WILL RESULT IN A VERY DISTINCT NON DIURNAL THERMAL TREND
DURING THE NIGHT AS AREA SLIDES INTO THE WARM SECTOR OF THE
CYCLONE FOR A WHILE. EASTERN AREAS AND THROUGH NORTHWEST IOWA
COULD EASILY HAVE WARMEST READINGS OCCUR DURING THE OVERNIGHT
HOURS...SOMETHING MODELS HAVE A HARD TIME REALIZING. HAVE MADE
SOME SIGNIFICANT CHANGES TO THERMAL TRENDS...BUT KEPT IN MIND THAT
SOME MINOR IMPACT FROM PRECIPITATION PRODUCTION IN TRANSLATING
WARM ADVECTION ZONE AHEAD OF CLIPPER MAY MODERATE THESE TRENDS
A BIT. AT THIS POINT...HAVE MODEST CHANCE POPS AS THE BETTER AND
DEEPER FORCING OCCURS WELL TO THE NORTHEAST...BUT STILL ENOUGH
THETA E ADVECTION FOR A FEW HOURS TO SATURATE TO ALLOW SOME
PRECIPITATION. WILL HAVE TO WATCH TYPE WITH SNEAKY WARMING ALOFT
SURGING EAST...AGAIN LIKELY MORE SIGNIFICANTLY THAN MODELS
INDICATE. OVERALL...MISSOURI VALLEY WOULD LIKELY FEEL FULL IMPACT
OF ANY OVERNIGHT WARMING. BY LATER NIGHT...COLD SURGE WORKING
BEHIND CLIPPER WAVE WILL PLUNGE SOUTHWARD INTO MUCH OF THE
CWA...AND STRONG LOW LEVEL COLD ADVECTION CONTINUES ON WEDNESDAY.

COULD VERY WELL AGAIN BE IN NEED OF WIND HIGHLIGHT FOR A TIME
WITH THIS SYSTEM WEDNESDAY...PERHAPS AS EARLY AS LATE TUESDAY
NIGHT. OTHER THAN THE WIND...WEDNESDAY SHOULD BE A QUIET DAY
BEHIND THE EXITING CLIPPER...WITH TEMPS LARGELY STAGNANT TO
FALLING. WHILE COLD AIR ADVANCES AT THE LOWER LEVELS...MID LEVEL
GRADIENT EXPECTED TO SLOW OR STALL ACROSS THE CWA HEADING INTO
WEDNESDAY EVENING...WITH ANOTHER QUICK MOVING WAVE ENHANCING
LIFT ACROSS THE BOUNDARY. HAVE BOLSTERED PRECIPITATION THREAT
ALONG THIS THERMAL RIBBON WEDNESDAY NIGHT...FOCUSING MAINLY NEAR
AND SOUTH OF INTERSTATE 90...BUT ENOUGH UNCERTAINTY IN EXACT
LOCATION TO KEEP A MINIMAL POP IN THE NORTHEAST.

HEADING INTO THANKSGIVING DAY WILL HAVE SOUTHWARD PUSH OF COLD
AND DRY AIR WHICH SHOULD SHUT OFF PRECIPITATION THREAT...BUT
SETTING UP WHAT COULD BE COLDEST HIGHS OF THE NEXT 7 DAYS.

IF ANYTHING...THE ENVELOPE OF POTENTIAL SOLUTIONS LATE WEEK ARE
EVEN MORE SPREAD THAN THE LAST COUPLE OF DAYS...WITH VERY FEW IN
THE MIDDLE. VAST MAJORITY OF SOLUTIONS FOLLOW LINES OF
ECMWF/CANADIAN WHICH DRIVE SOME VERY COLD LOW LEVEL AIR SOUTHWARD
FOR THANKSGIVING DAY AND FRIDAY...MODERATING A BIT BY SATURDAY.
GFS ON THE OTHER HAND HAS A QUITE MILD DAY SANDWICHED BETWEEN
THANKSGIVING AND SATURDAY. EACH MODELS SEEMS TO HAVE ITS OWN
PREFERRED LOCATIONS FOR BAROCLINICITY...AND REACTS BY VARIOUS
PERIODS OF LIGHT SNOWFALL FROM THURSDAY NIGHT INTO SATURDAY. AT
THIS TIME...HAVE CHOSEN THE LESS TRAVELED ROAD BY KEEPING THINGS
DRY...BUT STRONGLY SHADING TOWARD COOLER...WITH CONTRIBUTION OF
THE GFS AND ITS DERIVATIVES SEVERELY IMPACTING THE BLEND THIS
MORNING. THE LOCATION OF MAXIMUM SPREAD ACROSS THE NORTHERN PLAINS
ON FRIDAY MORNING ARE A MEASURE LOWER CONFIDENCE. TRACK OF CLIPPER
WAVES WILL MAKE POTENTIAL THERMAL ERRORS QUITE LARGE...BUT NOT AS
LARGE AS IF A MORE SIGNIFICANT SNOW COVER WAS IN PLACE. HAVE
SHADED LONGER RANGE TEMPS DOWN A TOUCH ON FRIDAY...BUT MAINLY
DAYTIME AS POTENTIAL CLOUDS IMPACT OVERNIGHT LOWS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 1055 PM CST SAT NOV 22 2014

EXPECT MVFR TO IFR CIGS AND VIS ACROSS NORTHWEST IOWA AND ADJACENT
PORTIONS OF SOUTHWEST MINNESOTA TONIGHT...SO INCLUDED MENTION IN THE
KSUX TAF. BASED ON OBS WILL KEEP KSUX MVFR...BUT IFR AND LIFR CIGS
ARE NOT TOO FAR AWAY AND COULD MOVE IN...SO SOMETHING TO WATCH.
COULD SEE SOME DENSE FOG FORM...ALTHOUGH LATEST GUIDANCE SUGGESTS
WIDESPREAD DENSE FOG IS PROBABLY BECOMING LESS LIKELY. AGAIN KFSD
WILL BE NEAR THE EDGE OF THIS STRATUS AND FOG...BUT BASED ON LATEST
MODEL GUIDANCE LEANING TOWARDS THEM STAYING VFR...BUT WILL CONTINUE
TO MONITOR. EXPECT ANY STRATUS TO CLEAR EARLY TO MID MORNING AS A
FRONT SWITCHES WINDS TO THE WEST AND NORTHWEST. COULD BE A LITTLE
LIGHT RAIN AS THE FRONT CROSSES...BUT NOT EXPECTING ANYTHING OF
SIGNIFICANCE AT THIS TIME. WINDS WILL INCREASE BEHIND THE
FRONT...AND BY LATE MORNING AND AFTERNOON EXPECTING GUSTS OF 30 TO
40 KTS TO BE COMMON AND LAST INTO THE OVERNIGHT. ALSO SHOULD SEE
STRATOCU DEVELOPMENT BEHIND THE FRONT IN THE COLD AIR ADVECTION
REGIME...WITH HEIGHTS LIKELY HIGH END MVFR OR LOW END VFR. ALSO
SHOULD BE SCATTERED FLURRIES OR SNOW SHOWERS INTO THE
OVERNIGHT...AND GIVEN THE STRONG WINDS COULD SEE BRIEF PERIODS OF
VISIBILITY REDUCTION...SO WILL HAVE TO WATCH FOR THAT AS WELL.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM NOON TODAY TO 9 PM CST THIS EVENING FOR
     SDZ038-050-052-053-057>059-063-064.

MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

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


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