000
FXUS63 KFSD 271645
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1045 AM CST TUE JAN 27 2015

.UPDATE...
ISSUED AT 1040 AM CST TUE JAN 27 2015

HAVE UPDATED THE FORECAST FOR THIS MORNING TO ISSUE A DENSE FOG
ADVISORY. SOUTHEAST FLOW ACROSS THE AREA MAKING IT DIFFICULT FOR
STRATUS TO ERODE ACROSS THE AREA. WINDS EXPECTED TO INCREASE
THROUGHOUT THE DAY...BUT STILL MAY NOT BE ENOUGH TO SCOUR OUT THE
CLOUDS. HAVE LOWERED FORECAST HIGHS FOR TODAY...ESPECIALLY IN THE
EAST.

FOR TONIGHT...NAM SHOWS THE STRATUS THICKENING WHILE THE RAP SHOWS
THE STRATUS THINNING AS WINDS INCREASE. IF THE STRATUS GETS THICK
ENOUGH...MAY NEED TO CONSIDER DRIZZLE BUT WILL TAKE A LOOK AT THAT
FOR THE AFTERNOON PACKAGE.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 257 AM CST TUE JAN 27 2015

ONLY AREA OF STRATUS VERY EARLY THIS MORNING IS SITUATED THROUGH
PORTIONS OF SOUTHWESTERN MINNESOTA INTO THE IOWA GREAT LAKES
AREA...WITH SOME PATCHY FOG LOCATED WITHIN THIS NARROW BAND. BOTH
THE RAP AND SREF ARE HANDLING THESE LOW CLOUDS/REDUCED VISIBILITY
WELL...AND HAVE IT DISSIPATING BY 15Z. OTHERWISE...THE REMAINDER OF
THE CWA REMAINS FOG FREE THIS MORNING SO REMOVED MOST OF THE FOG
FROM THE FORECAST. HIGH PRESSURE SITUATED ACROSS THE REGION THIS
MORNING WILL PUSH OFF TO THE EAST THROUGH THE DAY...AND AS IT DOES
SO THE LOW LEVEL FLOW WILL BECOME SOUTHEASTERLY. THIS AND A
STRENGTHENING INVERSION WILL INHIBIT MIXING TODAY...ESPECIALLY IN
THE EAST...AND IN RESPONSE HIGH TEMPERATURES WILL GENERALLY BE
COOLER THAN YESTERDAY. STILL VERY MILD FOR THIS TIME OF YEAR
HOWEVER...TOPPING OUT IN THE LOWER 40S THROUGH SOUTHWESTERN
MINNESOTA INTO THE EASTERN PORTIONS OF OUR IOWA ZONES...TO 50S
THROUGH THE JAMES RIVER VALLEY THROUGH THE LOWER MISSOURI RIVER
CORRIDOR.

A SURFACE TROUGH BEGINS TO APPROACH FROM THE WEST TONIGHT...AND IT
WILL BE A MILDER NIGHT WITH INCREASING WARM AIR ADVECTION OUT AHEAD
OF THE SYSTEM. WITH THAT...LOOKING AT LOWS GENERALLY LOWER TO MID
30S.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 257 AM CST TUE JAN 27 2015

WEDNESDAY STILL TO BE THE FINAL VERY MILD DAY AS LOW PRESSURE PASSES
AND COOLER AIR BEGINS TO DRAIN SOUTHWARD. MODELS SIMILAR TO
YESTERDAY SO NO REAL CHANGES. STILL MAINTAIN A SMALL CHANCE FOR
LIGHT SNOW IN THE NORTH AS A WAVE PASSES BY BUT A BIT MOISTURE
STARVED SO NOT ANTICIPATING MUCH OF ANYTHING.

BECOMING A BIT WINDY LATE WEDNESDAY AFTERNOON AND NIGHT AS COLD AIR
ADVECTION AND A STRONG PRESSURE GRADIENT WORK TO MIX DOWN SOME
STRONG WINDS ALOFT. LIKELY SEE SOME WIND GUSTS OF 35 MPH OR SO
WEDNESDAY NIGHT. WITH SOME CLOUD COVER AND WIND TEMPERATURES SHOULD
STAY FAIRLY MILD FOR THIS TIME OF YEAR WITH THURSDAY MORNING LOWS
FROM THE MID 20S TO LOWER 30S.

THURSDAY STILL A BIT BREEZY AND DEFINITELY COLDER. THE LOWER LEVEL
THERMAL FIELD HAS COME IN A BIT COLDER THIS TIME AROUND WHICH IS
ALSO FAIRLY WELL AGREED UPON SO WENT AHEAD AND LOWERED HIGHS A
COUPLE OF DEGREES. HIGHS MAINLY UPPER 20S TO MID 30S.

IN THE OUTER PERIODS (FRIDAY THROUGH MONDAY)...THE COLDER PATTERN
SETTLES IN AND REMAINS IN PLACE. MODELS ALL IN PRETTY GOOD AGREEMENT
THIS TIME AROUND SO WILL KEEP TEMPERATURES ON THE COLDER SIDE OF
GUIDANCE. FRIDAY IS THE LAST OF THE MILD DAYS AS SOUTHERLY FLOW
KEEPS 925MB TEMPERATURES CLOSER TO ZERO. SATURDAY LIKELY POSING THE
POTENTIAL FOR THE BIGGEST ERROR IN FORECASTING AS THE ARCTIC
BOUNDARY IS PROGGED TO MOVE THROUGH. A LITTLE FASTER AND HIGHS WILL
BE IN THE 20S...A LITTLE SLOWER AND HIGH WOULD BE IN THE 40S SO
UPPER 20S IN THE NORTH AND MID 30S IN THE SOUTH SEEMS LIKE A GOOD
HEDGE TOWARDS THIS FAIRLY SHARP THERMAL GRADIENT. WILL ALSO HAVE A
CHANCE FOR LIGHT SNOW ON SATURDAY AND SATURDAY NIGHT AS THIS COLD
AIR SURGES SOUTH. SUNDAY AND MONDAY WELL INTO THE COLD AIR SO JUST
LOOKING AT HIGHS IN THE TEENS TO LOWER 20S AND LOWS IN THE SINGLE
DIGITS TO LOWER TEENS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1040 AM CST TUE JAN 27 2015

HAVE AMENDED TAFS AT KFSD THIS MORNING TO KEEP LOW CLOUDS AND FOG
THROUGH EARLY AFTERNOON. ELSEWHERE...INCREASING SOUTHEASTERLY
WINDS ARE EXPECTED TODAY INTO TONIGHT. QUESTIONS REMAIN HOW LONG
STRATUS WILL HANG TOUGH...ESPECIALLY ACROSS SOUTHWEST MINNESOTA.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...DENSE FOG ADVISORY UNTIL 1 PM CST THIS AFTERNOON FOR SDZ040-056-
     062-067.

MN...DENSE FOG ADVISORY UNTIL 1 PM CST THIS AFTERNOON FOR MNZ071-072-
     080-089-097-098.

IA...DENSE FOG ADVISORY UNTIL 1 PM CST THIS AFTERNOON FOR IAZ001-002-
     012-013.

NE...NONE.
&&

$$

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