Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 281745
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1145 AM CST SAT FEB 28 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 426 AM CST SAT FEB 28 2015

HIGH PRESSURE WILL CONTINUE TO PUSH OFF TO THE EAST TODAY...AND WITH
WARM AIR ADVECTION IN AN INCREASING SOUTHERLY FLOW IT WILL BE A
RELATIVELY MILDER DAY. THIS WILL PLAY OUT TO HIGHS IN THE LOWER 20S
FROM EAST CENTRAL SD INTO THE IOWA GREAT LAKES AREA...TO LOWER 30S
THROUGH SOUTH CENTRAL SD. OTHERWISE...IT WILL ALSO BE A BIT BREEZY
AS THE GRADIENT TIGHTENS A BIT AND MIXED LAYER WINDS INCREASE.
MODELS CONTINUE TO TREND PRECIPITATION FARTHER TO THE SOUTH IN
ASSOCIATION WITH A WEAK SHORTWAVE SLIDING ACROSS NEBRASKA AND IOWA
LATE THIS AFTERNOON AND EVENING...SO REMOVED POPS FOR ALL BUT OUR
EXTREME SOUTHEASTERN ZONES IN THE AFTERNOON.

A SURFACE TROUGH SLIDES ACROSS THE AREA TONIGHT...BRINGING IN DRIER
AIR ON A NORTHWESTERLY FLOW. AGAIN TEMPERATURES WILL BE SOMEWHAT
MILDER THAN RECENT NIGHTS...THOUGH STILL BELOW NORMAL FOR THIS TIME
OF YEAR...BOTTOMING OUT IN THE UPPER SINGLE DIGITS TO LOWER TEENS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 426 AM CST SAT FEB 28 2015

WITH THE TROUGH CONTINUING TO SETTLE SOUTHWARD SUNDAY...ANY
PRECIPITATION CHANCE WILL REMAIN SOUTH OF THE AREA. ANTICIPATE FAIR
AMOUNT OF MID-HIGH CLOUDS TO START THE DAY...WITH DECREASING CLOUDS
BY AFTERNOON AS UPPER WAVE SWINGS THROUGH. MIXY WESTERLY FLOW WILL
LEAD TO ANOTHER RELATIVELY MILD DAY WHEN COMPARED TO RECENT TEMPS...
WITH HIGHS IN THE MID 20S-LOWER 30S EXPECTED. WEAK SHORTWAVE RIDGE
THEN MOVES ACROSS THE REGION MONDAY...LEADING TO WHAT SHOULD BE THE
WARMEST DAY OF THE NEXT FEW...THOUGH IT LIKELY WILL NOT FEEL MUCH
WARMER THAN SUNDAY WITH STOUT SOUTHERLY WINDS. WILL HANG ON TO A
SLIGHT CHANCE OF PRECIP IN OUR SOUTHERN AREAS MONDAY AFTERNOON AS A
WEAK MID LEVEL WAVE MOVES INTO THE AREA...THOUGH MAY NOT HAVE QUITE
ENOUGH MOISTURE IN PLACE TO PRODUCE MUCH PRECIP BY THAT TIME.

PRECIPITATION CHANCES RAMP UP MONDAY NIGHT AND TUESDAY AS STRONGER
TROUGH SWINGS OUT OF THE ROCKIES...AND INTERACTS WITH DEVELOPING
INVERTED TROUGH WHICH EXTENDS INTO OUR EASTERN CWA FROM SURFACE LOW
KICKING OUT OF COLORADO INTO THE CENTRAL PLAINS. GFS REMAINS A MORE
AGGRESSIVE OUTLIER WITH REGARDS TO LOW LEVEL WARMING AHEAD OF THE
INVERTED TROUGH...BRINGING THE WARM NOSE ABOVE FREEZING INTO OUR
SOUTHERN COUNTIES LATE MONDAY NIGHT. CANNOT COMPLETELY RULE THIS
SCENARIO OUT...AS IT HAS SUPPORT FROM A NUMBER OF THE GFS ENSEMBLE
MEMBERS. HOWEVER...WITH ECMWF AND CANADIAN BOTH KEEPING TEMPS ALOFT
IN THE SUB-FREEZING TERRITORY THROUGHOUT THE EVENT...WILL STICK WITH
JUST SNOW AT THIS RANGE. WILL DEFINITELY BE SOMETHING TO MONITOR AS
THE EVENT DRAWS CLOSER THOUGH. ALTHOUGH CONFIDENCE IS INCREASING IN
THE POTENTIAL FOR ACCUMULATING SNOW IN OUR AREA WITH THIS SYSTEM...
THERE IS LESS CONFIDENCE IN POTENTIAL QPF/SNOWFALL AMOUNTS. 00Z GFS
IS OVERALL WETTER THAN THE ECMWF/GEM AND OPTED TO ERR TOWARD THE
CONSERVATIVE SIDE OF MODEL PROJECTIONS FOR NOW. THIS STILL LEADS TO
POTENTIAL FOR 2-4 INCH SNOWFALL AMOUNTS FOR PARTS OF THE FORECAST
AREA...BUT AS MENTIONED ABOVE...CONFIDENCE IN THIS IS FAIRLY LOW AT
THIS TIME.

GREATER CONFIDENCE THAT TEMPERATURES WILL BE CRASHING THROUGHOUT THE
DAY TUESDAY AS THE INVERTED TROUGH EXITS THE AREA...FOLLOWED BY VERY
STRONG NORTHERLY FLOW AND COLD ADVECTION. TUESDAY MAX TEMPERATURE
FORECAST STILL LOOKS TO BE ON THE MILDER SIDE IN THE 20S TO AROUND
30...BUT GIVEN CURRENT FRONTAL TIMING...EXPECT THIS WILL BE SEEN
VERY EARLY IN THE DAY. WITH THE STRONG POST-FRONTAL WINDS...WILL
LIKELY SEE AREAS OF BLOWING SNOW AS WELL ON TUESDAY...AND ADDED A
MENTION OF THIS TO THE AFTERNOON...WHEN STRONGEST WINDS WILL IMPACT
AREA WHERE GREATER SNOWFALL IS MOST LIKELY.

ARCTIC AIR SETTLES BACK INTO THE REGION FOR WEDNESDAY WITH ANOTHER
ROUND OF WIND CHILL ADVISORIES POSSIBLE LATE TUESDAY NIGHT/WEDNESDAY
MORNING. WARMER AIR THEN TRIES TO PUSH EASTWARD INTO THE FORECAST
AREA LATE NEXT WEEK. DEGREE OF WARMING WILL BE IMPACTED BY SNOW
COVER FROM THE TUESDAY SYSTEM...SO WILL CONTINUE TO FAVOR COOLER END
OF GUIDANCE RANGE FOR NOW...THOUGH EVEN THAT SHOWS POTENTIAL FOR
MELTING IN MOST AREAS BY FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1144 AM CST SAT FEB 28 2015

A PERIOD OF MVFR CEILINGS IS LIKELY FOR KSUX THIS AFTERNOON AS
LOW LEVEL MOISTURE ADVECTS OFF THE NORTH EDGE OF SYSTEM IN THE
SOUTHERN PLAINS. FURTHER NORTHWARD...SHOULD REMAIN SCATTERED OR
PERHAPS A BRIEF PERIOD OF LOWER END VFR BROKEN CEILINGS. REMAINS
TO BE SEEN IF MVFR CEILINGS BEHIND WIND SHIFT CURRENTLY ACROSS
EASTERN MONTANA AND NORTHEASTERN WYOMING WILL SURVIVE AS FULL
FLEDGED CEILINGS ADVECTING TOWARD KHON AND EVENTUALLY KFSD LATER
IN THE NIGHT...BUT FOR NOW EXPECT SUBSIDENCE TO KEEP FROM A
PREVAILING CONDITION.

&&

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

$$

SHORT TERM...JM
LONG TERM...JH
AVIATION...CHAPMAN


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