Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 261105
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
505 AM CST MON JAN 26 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 257 AM CST MON JAN 26 2015

A SHORTWAVE DROPPING THROUGH MINNESOTA IN CONJUNCTION WITH LOW LEVEL
FRONTOGENESIS IS KICKING OFF A FEW RADAR RETURNS THROUGH OUR
NORTHEASTERN MINNESOTA ZONES VERY EARLY THIS MORNING. NOT SEEING
OBSERVATIONS REPORTING ANY TYPE OF PRECIPITATION WITH THESE
ECHOES...DUE TO DRIER AIR IN THE LOWER LEVELS...SO HAVE NOT INCLUDED
ANY POPS IN THE FORECAST. WILL BE SOMETHING TO KEEP AN EYE ON
THROUGH THE EARLY MORNING HOURS HOWEVER. OTHERWISE...AN AREA OF LOW
PRESSURE TRACKING ALONG THE U.S./CANADIAN BORDER IS POISED TO PULL A
FRONTAL BOUNDARY ACROSS OUR AREA DURING THE MORNING. THE MAIN RESULT
OF THIS FRONTAL PASSAGE WILL BE INCREASING NORTHWESTERLY WINDS OVER
THE AREA DURING THE AFTERNOON...AND WITH DECENT MIXING IT WILL BE A
VERY MILD DAY. CONTINUED TO STAY ON THE WARM SIDE OF GUIDANCE WITH
HIGHS RANGING FROM THE MID/UPPER 40S EAST OF A BROOKINGS TO STORM
LAKE LINE...TO THE MID AND UPPER 50S THROUGH THE MISSOURI RIVER
CORRIDOR.

A RIDGE OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION TONIGHT. THIS
WILL ALLOW WINDS TO DROP OFF OVERNIGHT IN A WEAKENING GRADIENT...AND
WHILE IT WILL NOT BE OVERLY COLD...WENT ON THE COOLER SIDE OF
GUIDANCE WITH THE LIGHT WINDS. THIS PLAYS OUT TO LOWS MAINLY IN
THE MID AND UPPER 20S.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 257 AM CST MON JAN 26 2015

TUESDAY A LITTLE TRICKY AS A FAIRLY STOUT INVERSION STRENGTHENS A
BIT THROUGH THE DAY AS AN UNFAVORABLE EAST TO SOUTHEAST WIND DOES
NOT SUPPORT A WHILE LOT OF MIXING. SO WHILE A PRETTY WARM AIR MASS
SPREADS ACROSS THE AREA...850MB TEMPERATURES POSSIBLY +10 TO +15
C...THE LOW SUN ANGLE AND POOR MIXING WILL ONLY GO SO FAR. STILL A
VERY NICE DAY EXPECTED WITH HIGHS IN THE 40S AND A FEW 50S IN THE
FAR SOUTHERN AND WESTERN CWA. WITH A BETTER SUN ANGLE AND NO SNOW ON
THE GROUND IN A COUPLE OF MONTHS FULL MIXING TO 850MB WOULD LIKELY
SUPPORT HIGHS IN THE 70S.

A STRONG SOUTHERLY GRADIENT LIKELY TO KEEP TEMPERATURES PRETTY MILD
ON TUESDAY NIGHT AS LOW PRESSURE APPROACHES FROM THE WEST. WILL SIDE
WITH THE WARMER GUIDANCE AND AIM FOR LOWS IN THE LOWER TO MID 30S.

WEDNESDAY WILL SEE THIS LOW PRESSURE SLIDE BY TO THE SOUTHEAST WITH
WINDS GRADUALLY TURNING TO THE NORTHWEST. NOT EXPECTING ANY
PRECIPITATION AS THE AIR MASS SEEMS TOO DRY SO SOME POTENTIAL TO
WARM UP. MODELS VARY QUITE A BIT ON HOW QUICKLY COOLER AIR SETTLES
IN SO TEMPERED HIGHS A BIT IN THE NORTH...AROUND 40...BUT STILL KEPT
LOWER 50S DOWN THE MISSOURI RIVER CORRIDOR. THESE TEMPERATURES MAY
ALSO NEED TO COME DOWN A BIT IF THIS COOLER AIR LOOKS TO WORK IN
FASTER.

IN THE OUTER PERIODS (THURSDAY THROUGH SUNDAY)...STILL LOOKING AT A
COLDER PATTERN DEVELOPING AS LOW PRESSURE DEEPENS OVER CENTRAL
CANADA. THIS WILL IN TURN DIRECT THE NORTHERN STREAM JET TO A MORE
NORTHERLY DIRECTION HELPING TO SUPPORT AND SUSTAIN COLDER AIR. AT
THIS TIME IT LOOKS LIKE THE BRUNT OF THE COLDEST AIR WILL HOLD OFF
UNTIL AT LEAST SUNDAY OR POSSIBLY MONDAY SO REALLY STILL LOOKING AT
TEMPERATURES ABOVE NORMAL DURING THIS TIME...JUST NOT AS FAR ABOVE
AS WE WILL HAVE BEEN. THERE ARE SOME FAIRLY SIGNIFICANT DIFFERENCES
IN THE SPEED OF THE FIRST SHOT OF COLD AIR WITH THE ECMWF DROPPING
THE COLDER AIR IN ON SATURDAY MORNING WHILE THE GFS WAITS UNTIL
SATURDAY EVENING. THEN ON SUNDAY THE GFS IS MORE AGGRESSIVE AT
SWINGING THROUGH A QUICK MOVING CLIPPER LIKE SYSTEM WITH THE EFFECTS
MAINLY TO THE NORTH OF THE AREA...BUT THIS WOULD BRING A QUICK SHOT
OF WARM AIR. THE ECMWF DOES NOT HAVE THIS WAVE AND THUS KEEPS US
BURIED IN THE COLDER AIR. UNFORTUNATELY TAKING THE STATISTICAL
GUIDANCE FROM THE GFS INTO ACCOUNT...THE ENSEMBLE MUCH COLDER THAN
THE OPERATIONAL...AND THE MORE AMPLIFIED CANADIAN THIS FIRST SHOT OF
COLD AIR MAY BE THE ONLY SHOT AS IT SEEMS MORE LIKELY THAT WE WILL
GET BURIED IN THE COLD AIR. WILL SIDE CLOSER TO THE COLDER WPC/ECMWF
VALUES ON THE WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 504 AM CST MON JAN 26 2015

VFR CONDITIONS THROUGH THE TAF PERIOD. NORTHWESTERLY WINDS WILL
INCREASE THROUGH THE LATE MORNING INTO THE AFTERNOON...GUSTING
CLOSE TO 25 KTS AT TIMES.

&&

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

$$

SHORT TERM...JM
LONG TERM...08
AVIATION...JM


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