Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 291746
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1146 AM CST THU JAN 29 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CST THU JAN 29 2015

A FAST MOVING SHORTWAVE HAS EXITED THE REGION EARLY THIS
MORNING...HOWEVER A SECOND WAVE HAS BEGUN DIGGING INTO THE WESTERN
CWA HOT ON ITS HEELS. LOW LEVEL STRATUS CONTINUES TO BLANKET THE
FORECAST AREA AND WITH THE ADDED LIFT OF THE SHORTWAVES...SOME
PATCHY DRIZZLE REMAINS. ONCE THE SECOND SHORTWAVE QUICKLY DROPS
ACROSS THE AREA...DRIZZLE CHANCES TAPER OFF QUICKLY AS THE WEAK LIFT
WANES AND THE LOWER LEVEL CLOUD DECK THINS SOME. NOT EXPECTING MUCH
IN THE WAY OF MEASURABLE PRECIPITATION...SO WILL LEAVE OUT POP
MENTION AFTER DAYBREAK...WITH NON MEASURABLE DRIZZLE/FREEZING
DRIZZLE LINGERING INTO MID MORNING IN THE FAR EAST.

CLOUDS WILL BE ABUNDANT INTO MIDDAY WITH THE MAIN COLD AIR ADVECTION
PUSH WORKING SOUTHWARD. A FEW BRIEF BREAKS WILL BEGIN TO FORM IN THE
AFTERNOON...MAINLY IN SOUTH CENTRAL SD AND THE MISSOURI
VALLEY...HOWEVER THE DRIER LOW TO MID LEVELS WILL NOT WORK INTO THE
REST OF THE REGION UNTIL THIS EVENING. TEMPERATURES WILL NOT WARM
MUCH ABOVE LOWS THIS MORNING...WITH HIGHS IN THE UPPER 20S TO MID
30S. WINDY CONDITIONS WILL BE ON AN OVERALL DOWNWARD TREND THROUGH
THE DAY. ALTHOUGH WINDS ARE CURRENTLY BELOW ADVISORY LEVEL...RADAR
VAD WIND PROFILES SUGGEST THAT 40 KT WINDS REMAIN JUST ABOVE THE
SURFACE. THE SECONDARY WAVE COULD BRIEFLY INCREASE SUSTAINED WINDS
AND GUSTS BACK TO ADVISORY LEVEL..SO WILL CONTINUE TO MONITOR AND
PERHAPS TRIM SOME COUNTIES IF THE DOWNWARD TREND CONTINUES.

WINDS DROP BELOW 10 KT AND GRADUALLY TURN SOUTHEASTERLY TONIGHT. THE
MOSTLY CLEAR TO PARTLY CLOUDY SKIES ALONG WITH A COLDER AIRMASS WILL
DROP LOWS INTO THE MID TEENS TO MID 20S. WHILE QUITE A BIT COLDER
THAN RECENT NIGHTS...THIS IS STILL ABOVE NORMAL FOR THIS TIME OF
YEAR.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 AM CST THU JAN 29 2015

FRIDAY WILL BE A DAY OF WARMING AND DRYING WITH A MODEST
SOUTHERLY BREEZE AND TEMPERATURES GETTING BACK TO SEVERAL
DEGREES ABOVE FREEZING. AGAIN THE MET GUIDANCE IS NOT WARM
ENOUGH WITH THE NAM SEEMINGLY TOO COOL AT LOW LEVELS AS USUAL. MID
30S EAST TO MID 40S WEST SEEMS OK FOR HIGHS. SKIES SHOULD BE MOSTLY
SUNNY AS CLOUDS FROM THE SOUTHWESTERN USA SYSTEM HOLD TO THE
SOUTH. FRIDAY NIGHT SHOULD BE TAME AS WELL WITH LOWS IN THE 20S AS
WEAK SURFACE TROUGH PASSES ACROSS AREA.

MODELS SHOW A DIFFERENCE ON HOW QUICKLY THE COLDER AIR PUSH BEGINS
SATURDAY. THE GFS AND EC ARE FASTER AND STRONGER ON BRINGING THE
COLDER AIR IN...TRYING TO MERGE THE COLD FRONT WITH THE LEADING
SURFACE TROUGH. THE NAM AND CANADIAN ARE SLOWER. WHILE PLAYING
BETWEEN THESE SOLUTIONS SEEMS LIKE A GOOD IDEA...I WOULD LEAN A
LITTLE TO THE FASTER COLD AIR PUSH ONCE THE TROUGH PASSES FRIDAY
NIGHT. THIS WILL NOT MAKE A HUGE DIFFERENCE SATURDAY BUT IT SEEMS
WORTH CUTTING THE EARLIER HIGHS WE HAD FOR THAT DAY BY 2 OR 3
DEGREES...IT DOES NOT SEEM TO BE TO THE STEADY/FALLING TEMPERATURE
STRENGTH YET. WITH THE SOUTHERN USA SYSTEM SEEMINGLY DESTINED TO
HOLD SOUTH OF THE AREA...WILL CUT THE SMALL LIGHT SNOW CHANCES FOR
SATURDAY DAYTIME.

SATURDAY NIGHT AND POSSIBLY INTO SUNDAY WILL BRING...BESIDES THE
STRONG INFLUX OF COLDER AIR...A THERMAL PATTERN SUPPORTIVE OF LIGHT
SNOW. POPS FOR MEASURABLE SNOW WILL STAY IN THE CHANCE CATEGORY FOR
NOW...AS TO GET MORE THAN FLURRIES OR A TENTH OF AN INCH WE WILL
NEED A LITTLE UPPER SUPPORT AND RIGHT NOW THAT SEEMS MARGINAL.
HOWEVER...IF IT DEVELOPS...AND THE EC IN PARTICULAR HINTS THAT
II COULD...THERE COULD BE AN INCH OR SO IN PLACES. ANY SNOW SHOULD
EXIT DURING THE DAY SUNDAY AS THE COLD SURFACE HIGH APPROACHES AND
ANY UPPER SUPPORT MOVES TO THE EAST/SOUTHEAST. SUNDAY HIGHS WILL
ACTUALLY BE BELOW NORMAL WITH TEENS TO LOWER 20S...AND THIS COULD BE
A LITTLE TOO WARM WITH AN INCH OR SO OF FRESH SNOW.

MONDAY THROUGH WEDNESDAY APPEARS TO BRING A SLIGHT INITIAL WARMUP
FOLLOWED BY A STRENGTHENING WEST NORTHWESTERLY UPPER FLOW...AND SOME
SLIGHT LIGHT SNOW CHANCE. NO RETURN TO THE RECENT WARMTH IS SEEN. IN
FACT...THE EC DEVELOPS A STRONGER AND DEEPER BROAD TROUGH OVER THE
CONTINENT AND TURNS IT QUITE A BIT COLDER DURING MIDWEEK. WILL GO
WITH THE MODERATE EXTENDED GUIDANCE FORECAST FOR NOW

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1142 AM CST THU JAN 29 2015

MVFR STRATUS WILL GRADUALLY ERODE FROM WEST TO EAST THROUGH THE
AFTERNOON HOURS INTO THE EARLY EVENING. WEAK SURFACE RIDGE WILL
MOVE THROUGH THE AREA DURING THE OVERNIGHT...WITH SOUTHERLY FLOW
DEVELOPING ACROSS THE AREA. MODEL SOUNDINGS SUGGEST A STRATUS
LAYER DEVELOPING ACROSS NORTHWEST IOWA TOMORROW MORNING DUE TO
MIXING...BUT AM UNCERTAIN OF THE HEIGHT AT THIS POINT. FOR
NOW...FOLLOWED LAV GUIDANCE AND PUT IT AT THE TOP OF MVFR RANGE.


&&

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

$$

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


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