Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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175
FXUS63 KFSD 110348
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
948 PM CST WED FEB 10 2016

.UPDATE...
ISSUED AT 918 PM CST WED FEB 10 2016

00Z DATA HAS SPED UP THE SOUTHEASTWARD MOVEMENT OF THE UPPER WAVE
TRACKING OUT OF THE PACIFIC NORTHWEST THIS EVENING AS 300MB JET
TRENDING SLIGHTLY FASTER THIS EVENING. HRRR/RAP/NAM/GFS ALL
SUPPORT FAIRLY RAPID SNOW DEVELOPMENT AFTER DAYBREAK ACROSS NORTH
CENTRAL SOUTH DAKOTA AND THEN QUICKLY MOVING THE WAVE SOUTHEAST IN
THE AFTERNOON. 00Z MODELS SHOWED INCREASING 850MB WARM ADVECTION
PEAKING BETWEEN 18-21Z WITH A SLIGHT THERMAL NOSE FORMING ON THE
NAM SOLN. MODELS ALSO SHOWING A BRIEF PERIOD OF HEALTHY
FRONTOGENESIS WITHIN THE 850:750 MB LAYER...SO AM ANTICIPATING
POTENTIAL FOR A STRONGER NARROW BAND AROUND MID-DAY. THERE WILL BE
SOME POTENTIAL FOR A LOW- LVL CIRCULATION OVER NORTH CENTRAL
NEBRASKA WHICH COULD HELP ENHANCE THE LIFT FOR A BRIEF PERIOD.

THAT SAID...MUCH LIKE WHAT HAPPENED WITH WEDNESDAYS SNOW...HAVE
ADJUSTED TIMING OF ARRIVAL FASTER INTO THE CWA. I HAVE ALSO BUMPED
UP POPS OVER MOST AREAS...BUT ESPECIALLY ALONG MAIN TRACK OF THE
WAVE. MODEL QPF HAS ALSO TRENDED SLIGHTLY HIGHER THIS EVENING...WITH
AN AVERAGE QPF AROUND 0.10 CUTTING THROUGH THE CWA. THIS WOULD
BUMP UP SNOW TOTALS SLIGHTLY OVER AN INCH IN SOME LOCATIONS.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 318 PM CST WED FEB 10 2016

BAND OF LIGHT SNOWFALL HAS DISSIPATED ACROSS THE AREA THIS
AFTERNOON...WITH ONLY A FEW LINGERING FLURRIES IN OUR FAR EASTERN
COUNTIES THROUGH THE NEXT HOUR OR SO. STRATUS CONTINUES TO BLANKET
AREAS ALONG AND EAST OF THE JAMES RIVER. SATELLITE IMAGERY SUGGESTS
THAT THIS BAND WILL SINK SOUTH THROUGH THE EVENING...WITH MOSTLY
CLOUDY TO CLOUDY SKIES EXPECTED TO PREVAIL OVERNIGHT. SOME CLEARING
OR SCATTERING OF THE CLOUDS MAY WORK INTO THE NORTHEASTERN CORNER OF
THE FORECAST AREA LATE THIS EVENING AND OVERNIGHT...HOWEVER CLOUDS
REBUILD FROM WEST TO EAST AGAIN THURSDAY MORNING IN ADVANCE OF THE
NEXT SHORTWAVE. LOW TEMPERATURES WILL AGAIN BE VARIABLE ACROSS THE
FORECAST AREA AS THE BAROCLINIC ZONE HOVERS NEAR OUR FAR WESTERN
COUNTIES. EXPECT LOWS NEAR ZERO IN THE EXTREME EAST...TO THE LOWER
OR MID 20S IN THE EXTREME WEST.

THE AFOREMENTIONED MID LEVEL SHORT WAVE DIVES SOUTH SOUTHEAST FROM
CANADA ON THURSDAY ON A SIMILAR TRAJECTORY AS TODAYS SYSTEM. WITH
THE LOW LEVEL THERMAL BOUNDARY IN PLACE ACROSS SOUTH CENTRAL
SD...LIGHT SNOW WILL BEGIN SPREADING INTO THE JAMES VALLEY AREA LATE
MORNING AND SPREADS SOUTHEAST THROUGH THE AFTERNOON. DID INCREASE
POPS TO HIGH CHANCES BY LATE AFTERNOON FOR A LARGE PORTION OF THE
CWA...BUT SNOWFALL AMOUNTS WILL GENERALLY BE A HALF INCH OR LESS
THROUGH SUNSET.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 318 PM CST WED FEB 10 2016

HAVE CONTINUED TO RAISE POPS FOR THE WAVE THURSDAY NIGHT INTO
FRIDAY.  WHERE THERE IS NOT A LOT TO HANG ON TO
DYNAMICALLY...ISENTROPIC LIFT EARLY ON TRANSITIONS TO A FAIRLY
EFFICIENT ATMOSPHERE FOR SNOW AS COLDER AIR STARTS TO WORK INTO THE
AREA.  HAVE THE HIGHEST POPS CONCENTRATED WITH THE ISENTROPIC LIFT
THURSDAY EVENING...BUT LEFT SOME CHANCES POPS EARLY FRIDAY MORNING
AS DENDRITIC LAYER DEEPENS NEAR THE SURFACE.  AS THE DENDRITIC LAYER
DEEPENS...ATMOSPHERE DRIES OUT AND CLEARING IS EXPECTED TO DEVELOP
FROM NORTHEAST TO SOUTHWEST ACROSS THE FORECAST AREA.  925 HPA TEMPS
FALL THROUGHOUT THE DAY...AND EXPECT TEMPERATURES TO REMAIN STEADY
OR FALL AS COOLER AIR BECOMES ESTABLISHED ACROSS THE AREA.

FRIDAY NIGHT LOOKS TO BE A GOOD RADIATIONAL NIGHT ESPECIALLY IN THE
EAST. CLOUDS WILL ADVANCE FROM WEST TO EAST KEEPING CENTRAL SOUTH
DAKOTA WARMER THAN AREAS TO THE EAST.

ANOTHER WAVE IS EXPECTED TO MOVE INTO THE REGION ON SATURDAY.
SOUTHEASTERLY WINDS LOOK TO BE FAIRLY STRONG WITH THIS WAVE...AND
GIVEN THE STRENGTH HAVE INCREASED THE POPS ACROSS MUCH OF THE
FORECAST AREA. ALOFT...FORECAST AREA IS LOCATED IN THE LEFT EXIT
REGION OF THE UPPER JET ACROSS THE MIDDLE OF THE COUNTRY LEADING TO
ENHANCED LIFT. HAVE KEPT POPS ACROSS EASTERN CWA LOWER DURING THE
DAY ON SATURDAY AS WAVE WILL BE FIGHTING A FAIR AMOUNT OF DRY AIR.
THE TRACK OF THE WAVE IS STILL SOMEWHAT UNCERTAIN...WITH THE GFS
LOCATED A FEW HUNDRED MILES SOUTH OF THE ECMWF AND GEM.

WARMER WEATHER IS EXPECTED SUNDAY NIGHT INTO AT LEAST TUESDAY AS 925
HPA TEMPS RISE ABOVE ZERO. ECMWF SUGGESTS A STRONG ARCTIC FRONT
RETURNING TO THE PLAINS ON WEDNESDAY...WHILE THE GFS SHOWS THE RIDGE
HOLDING ON THROUGH MIDWEEK. FOR NOW...STUCK WITH CONSENSUS GUIDANCE
TO SEE WHICH PATTERN WILL WIN OUT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 540 PM CST WED FEB 10 2016

NARROW CORRIDOR OF STRATUS WILL REMAIN INTO THE OVERNIGHT
HOURS...LIKELY BEGINNING TO EXPAND OVER NORTH CENTRAL SD AND DRIFT
SOUTHEAST BY DAYBREAK. A BIT OF AN UNCERTAIN FORECAST FOR FSD...AS
THERE MAY BE INTERMITTENT STRETCHES OF PREVAILING VFR CIGS WITH
OCCASIONAL DROPS TO MVFR CATEGORIES. MVFR STRATUS SHOULD PREVAIL
AT KHON FOR MOST OF THE OVERNIGHT HOURS...WITH KSUX REMAINING ON
THE EDGE OF ANY LOWER CEILINGS THROUGH MORNING.

SNOW WILL BEGIN TO MOVE SOUTHEAST INTO THE TERMINALS BY MID-LATE
MORNING THURSDAY. MAY SEE PREVAILING MVFR CONDITIONS...WITH HIGHER
PROBABILITIES OF IFR CONDITIONS LATER IN THE AFTERNOON.
ACCUMULATIONS WILL BE RATHER LIGHT...WITH MOST AREAS ONLY SEEING
UPWARDS OF AN INCH OF SNOW.


&&

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

$$

UPDATE...DUX
SHORT TERM...
LONG TERM...
AVIATION...DUX



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