Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 232312
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
512 PM CST MON FEB 23 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 337 PM CST MON FEB 23 2015

MILD BUT BREEZY/WINDY CONDITIONS WILL BE THE PRIMARY FOCUS FOR THE
NEXT 24 HOURS. FOR THE OVERNIGHT HOURS...MAIN CONCERN IS GUSTY WINDS
AS LOW LEVEL JET INCREASES ACROSS THE REGION. WITH SOUTHWEST FLOW
CROSSING THE HIGHER ELEVATIONS IN THE BUFFALO RIDGE...POTENTIAL
THERE TO MIX STRONGER WINDS TO THE SURFACE THAN OVER THE REMAINDER
OF THE FORECAST AREA. HAVE BUMPED WIND GUSTS UP IN FAVORED AREAS
ATOP AND ON THE DOWNSLOPE SIDE OF THE SHARPEST TERRAIN TO NEAR OR
JUST ABOVE ADVISORY CRITERIA...A LITTLE HIGHER THAN THE PREVIOUS
FORECAST. HOWEVER...THINK STRONGEST WINDS WILL BE RELATIVELY BRIEF
IN DURATION GIVEN SLACKENING GRADIENT AFTER 06Z WITH THE APPROACH OF
WEAK SURFACE TROUGH/WIND SHIFT. THUS OPTED TO NOT ISSUE AN ADVISORY.
WILL UPDATE HWO TO HIGHLIGHT POTENTIAL.

TOMORROW SHOULD BE A GOOD MIXING DAY WITH WESTERLY FLOW EARLY
BECOMING NORTHWEST TO NORTHERLY AS A COLD FRONT PUSHES THROUGH THE
REGION. DID COOL TEMPERATURES A BIT MORE QUICKLY IN THE MID-LATE
AFTERNOON THAN PREVIOUS FORECAST AS COOLER AIR DOES SETTLE IN JUST A
BIT QUICKER. HOWEVER GIVEN LACK OF SNOW COVER AND TENDENCY TO WARM
MORE THAN MOST MODEL GUIDANCE HAS ALLOWED IN RECENT WARM SPELLS...
WILL CONTINUE THE TREND FROM PREVIOUS SHIFT IN HEDGING TOWARD THE
WARMER GUIDANCE SOLUTIONS WITH HIGHS FROM AROUND 30 ACROSS OUR
NORTHEAST...TO AROUND 40 IN THE MISSOURI RIVER VALLEY. FORECAST
SOUNDINGS SHOWING A SHALLOW POST-FRONTAL CONVECTIVE LAYER WHICH
COULD TRIGGER SCATTERED FLURRIES. DO NOT EXPECT MUCH IF ANY
ACCUMULATION FOR MOST AREAS. HOWEVER HAVE ADDED ISOLATED SNOW
SHOWERS TO PARTS OF EAST CENTRAL SD/SOUTHWEST MN WHERE THERE
APPEARS TO BE A GREATER POTENTIAL FOR VISIBILITY TO BRIEFLY BE
REDUCED IN CONVECTIVE SNOW SHOWERS.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 337 PM CST MON FEB 23 2015

MAIN FOCUS TUESDAY NIGHT INTO WEDNESDAY WILL BE OUR SNOW POTENTIAL.
A WAVE TRACKING ALONG THE STRONG THERMAL GRADIENT WILL RESULT IN A
PERIOD OF DECENT LIFT AND A BAND OF LIGHT TO MODERATE SNOW. STILL
SOME MODEL DISCREPANCIES WITH REGARD TO THE PLACEMENT OF THIS BAND.
NAM AND SREF SOLUTIONS HAVE BEEN DISREGARDED...AS THEY SEEM NOT TO
HAVE A GOOD HANDLE ON THE LARGE SCALE FEATURES AT THIS TIME. THUS
FORECAST LEANED TOWARDS A BLEND OF QPF FROM WPC...GFS...ECMWF AND
GEM. THIS SEEMED TO RESULT IN A GOOD COMPROMISE BETWEEN THE
GFS...WHICH IS PROBABLY TOO FAR SOUTH...AND THE MORE NORTHERN
ECMWF...UKMET AND GEM. VERTICAL TEMPERATURE PROFILE SEEMS A BIT TOO
WARM TO ALLOW FOR VERY HIGH RATIOS...AND THUS THINK AROUND 13:1
SHOULD BE OKAY FOR MOST OF THE EVENT. THIS RESULTS IN A GOOD 1 TO 4
INCHES OVER MOST OF THE CWA...WITH THE HIGHEST AMOUNTS IN THE
VICINITY OF THE MISSOURI RIVER. THIS AXIS OF HIGHER AMOUNTS MAY
STILL SHIFT A BIT NORTH OR SOUTH AS MODELS CONTINUE TO NARROW IN ON
THE FINAL SOLUTION. BASED ON MODEL QPF...WOULD NOT BE SURPRISED TO
SEE A FEW AMOUNTS AROUND 5 INCHES...BUT GIVEN UNCERTAINTY ON
WHERE...DID NOT WANT TO GO THAT HIGH IN THE FORECAST AT THIS TIME.
TIMING OF MOST OF THE SNOW IS AFTER MIDNIGHT TOMORROW NIGHT...ENDING
FROM NORTHWEST TO SOUTHEAST WEDNESDAY MORNING INTO EARLY AFTERNOON.

ONCE THE SNOW ENDS...THE STORY WILL BE THE WELL BELOW NORMAL
TEMPERATURES. HIGHS THURSDAY LIKELY ONLY IN THE SINGLE DIGITS AND
TEENS...WITH TEENS ON FRIDAY. WIND CHILLS WEDNESDAY NIGHT INTO
THURSDAY MORNING SHOULD FALL BACK INTO THE -15 TO -25 RANGE. WITH
HIGH PRESSURE OVERHEAD AND POTENTIAL NEW SNOW...FRIDAY MORNING COULD
BE QUITE COLD. TRENDED LOWS DOWN A BIT...MAINLY BETWEEN -4 AND -7.
BUT COULD EVEN END UP A BIT COLDER THAN THIS.

WEATHER COULD BECOME MORE ACTIVE AGAIN BY THIS WEEKEND. A STRONG
UPPER WAVE WILL CARVE OUT A LARGE TROUGH OVER THE WESTERN PORTION OF
THE COUNTRY. SHORTWAVES WILL EJECT OUT OF THIS TROUGH INTO THE
PLAINS...JUST A MATTER OF HOW FAR NORTH THE BETTER FORCING AND
MOISTURE CAN GET. AS QUICK NORTHERN STREAM WAVES WILL BE ACTING TO
SUPPRESS THE ACTIVITY TO THE SOUTH. SO ALL A MATTER OF
TIMING...WHICH THIS FAR OUT IS TOUGH TO PREDICT. AT THIS TIME IT
LOOKS LIKE A CHANCE OF SNOW ANYTIME FROM SATURDAY AFTERNOON INTO
SUNDAY...WITH THE HIGHEST CHANCES IN THE SOUTH. DECENT ACCUMULATIONS
SEEM PROBABLE WITH THIS SYSTEM...BUT WHETHER THESE STAY SOUTH OF OUR
AREA OR GET INTO THE CWA IS YET TO BE KNOWN. THUS WILL HAVE TO
CONTINUE TO MONITOR TRENDS. EITHER WAY BELOW NORMAL TEMPERATURES
WILL CONTINUE WITH HIGHS IN THE 20S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 508 PM CST MON FEB 23 2015

WINDS WILL TRANSITION TO NORTHWESTERLY AND PICK UP LATE TONIGHT
BEHIND A FRONTAL BOUNDARY...GUSTING TO AROUND 25 KTS BY TUESDAY
MORNING. THERE COULD BE UPPER END MVFR CEILINGS BEHIND THIS
BOUNDARY...MORE LIKELY AT KHON.

&&

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

$$

SHORT TERM...JH
LONG TERM...CHENARD
AVIATION...JM



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