Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 302046
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
246 PM CST FRI JAN 30 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 246 PM CST FRI JAN 30 2015

CLEAR SKIES ARE EXPECTED ACROSS THE AREA THROUGH THE EVENING
HOURS...THEREAFTER...A COLD FRONT WILL SLIDE THROUGH THE REGION BUT
HANG UP SATURDAY MORNING ACROSS NORTHWEST IOWA AS A SERIES OF WAVES
BREAK OFF UPPER LEVEL LOW OVER THE DESERT SOUTHWEST. NORTHEAST FLOW
WILL INCREASE AHEAD OF WAVE DURING THE DAY ON SATURDAY...MAKING IT
DIFFICULT TO WARM UP. MODELS SOUNDINGS ALSO SUGGEST DEEPENING
STRATUS QUICKLY DEVELOPING IN THE NORTHEAST FLOW. WITH DEEPENING
CLOUD COVER AND NORTHEAST FLOW...HAVE SQUASHED DIURNAL SPREAD ON
SATURDAY.

BY SATURDAY AFTERNOON...FORECAST AREA IS LOCATED IN RIGHT REAR
QUADRANT OF JET STREAK ACROSS THE EASTERN TIER OF THE US.  WITH WAVE
APPROACHING FROM THE SOUTHWEST...SHOULD SEE ENOUGH SATURATION
THROUGH THE DENDRITIC LAYER ACROSS THE SOUTH TO LEAD TOWARDS SNOW
DEVELOPING.  HAVE INCREASED POPS INTO THE CATEGORICAL RANGE TOMORROW
AFTERNOON ACROSS NORTHWEST IOWA...EXPANDING NORTHWARD THROUGH THE
LATE AFTERNOON HOURS.  THERE IS A SECOND WAVE APPROACHING IN THE
NORTHERN STREAM OF THE JET...BUT ITS EFFECTS MAINLY HOLD OFF TILL
AFTER 00Z.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 246 PM CST FRI JAN 30 2015

MODELS IN REALLY GOOD AGREEMENT SATURDAY NIGHT INTO SUNDAY MORNING
ON SWINGING THROUGH A NICE SNOW MAKING SYSTEM. THE MODELS BEGAN TO
AGREE ON LAST NIGHTS RUNS AND THE 6Z AND NOW 12Z RUNS SUPPORT THE
INCREASE THREAT FOR SNOW. A PIECE OF ENERGY FROM THE SOUTHWEST
UNITED STATES LOW PRESSURE AND AN INCOMING NORTHERN STREAM WAVE WILL
MERGE NEAR THE AREA...WHICH SLOWS THINGS DOWN A BIT AND BRINGS A
BETTER CHANCE FOR SNOWFALL. THE BEST CHANCE LOOKS TO BE FROM ABOUT
3Z SUNDAY THROUGH 12Z SUNDAY. A VERY DEEP DENDRITIC LAYER WILL WORK
WITH SOME DECENT FORCING AND MOISTURE TO ALLOW THE SNOWFALL TO
DEVELOP. AS THE NORTHERN STREAM PV ANOMALY PASSES ON SUNDAY MORNING
THE THREAT FOR SNOWFALL SHOULD DIMINISH PRETTY QUICKLY. WHILE IT
WILL BE A BIT WINDY LATE SATURDAY NIGHT INTO SUNDAY NOT PLANNING ON
A LOT OF BLOWING SNOW SINCE THERE IS LITTLE TO NO SNOW ON THE GROUND
RIGHT NOW. MODEL QPF ALSO PRETTY AGREEABLE AVERAGING THREE TO FOUR
TENTHS OVER THE SOUTHEAST THIRD OF THE CWA...THEN DIMINISHING TO
ABOUT A TENTH OF AN INCH NEAR 9V9 AND HON. THE NAM IS THE ONLY ONE
THAT BRINGS THESE HIGHER QPF AMOUNTS INTO SOUTHWEST MINNESOTA AND IS
RUNNING ABOUT THREE TENTHS HIGHER THAN THE OTHER MODELS...SO WILL
MOSTLY IGNORE ITS OUTPUT. BECAUSE FREQUENTLY THE MODELS SEEM TO
OVERDUE QPF AMOUNTS JUST A BIT...WILL KEEP QPF TOTALS CLOSER TO A
QUARTER TO A HALF AN INCH AT THIS TIME. THIS PLACES TWO TO FOUR
INCHES OF SNOW SOUTH AND EAST OF A YANKTON TO SIOUX FALLS TO WINDOM
LINE...WITH THE HIGHER AMOUNTS TOWARDS SPENCER IOWA AND STORM LAKE.

IN THE OUTER PERIODS (TUESDAY THROUGH FRIDAY)...ANOTHER LOBE OF
ENERGY EXPECTED TO SWING AROUND THE LOW PRESSURE IN CENTRAL CANADA
TUESDAY NIGHT INTO WEDNESDAY. THIS WILL BRING A SMALL CHANCE FOR
LIGHT SNOW TUESDAY AND A REINFORCING SHOT OF COLD AIR. THIS ENERGY
IS FAIRLY WELL AGREED UPON BY THE MODELS. THURSDAY INTO FRIDAY UPPER
LEVEL RIDGING BUILDS IN SO EXPECT MODERATING TEMPERATURES INTO
FRIDAY. THE COLDEST DAYS RIGHT NOW LOOK TO BE ON WEDNESDAY AND
THURSDAY WITH TEMPERATURES GETTING BACK CLOSER TO NORMAL ON FRIDAY.
WITH SOME NEW SNOW LIKELY ON THE GROUND WILL NOT GET TOO EXCITED
ABOUT THE WARMING AT THIS TIME. WILL SIDE TOWARDS THE COOLER SIDE OF
GUIDANCE...ESPECIALLY ON WEDNESDAY AND THURSDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1145 AM CST FRI JAN 30 2015
IFR STRATUS SHIFTING EAST OUT OF THE AREA ACROSS SOUTHWEST
MINNESOTA THIS AFTERNOON. MODEL SOUNDINGS SUGGEST STRATUS MAY TRY
TO EXPAND ON THE WESTERN EDGE DUE TO MIXING...BUT CONFIDENCE IS
NOT THERE ON HOW WIDESPREAD IT WOULD BE. FOR NOW...CARRIED FEW-
SCATTERED IN BOTH KSUX AND KFSD TAF. FOR TONIGHT...NORTHEAST FLOW
INCREASES AFTER 06Z AND MODEL SOUNDINGS SUGGEST FAIRLY DENSE
STRATUS DEVELOPING. MODEL GUIDANCE HINTS AT IT...BUT IS NOT AS LOW
AS SOUNDINGS WOULD SUGGEST. FOR NOW...SIDED WITH LOW MVFR...BUT
COULD BE IFR SATURDAY MORNING AT MOST LOCATIONS.

&&

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

$$

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



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