Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 181717
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1217 PM CDT THU SEP 18 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 306 AM CDT THU SEP 18 2014

MOSTLY CLEAR SKIES OUT THERE EARLY THIS MORNING WITH THE STRATUS
WELL SOUTH AND EAST OF OUR CWA. BASED ON THESE TRENDS...AND SREF AND
HRRR GUIDANCE...BACKED OFF ON FOG MENTION AND CLOUD COVER THIS
MORNING. STILL THINK WE COULD SEE SOME PATCHY FOG...BUT FOR THE MOST
PART THIS SHOULD BE CONFINED TO THE MISSOURI RIVER AND POINTS SOUTH.
MODEL SOUNDINGS STILL SUGGEST STRATOCU DEVELOPMENT IS QUITE POSSIBLE
AFTER SUNRISE. NOT A SURE BET...BUT WILL KEEP SOME HIGHER CLOUD
COVER IN DURING THE MORNING TO ACCOUNT FOR THIS. WITH THE DEEPER
MOISTURE STAYING SOUTH...THINK AS WE CONTINUE TO MIX THE MOSTLY
CLOUDY SKIES WILL BECOME PARTLY CLOUDY BY AFTERNOON. THUS WENT AHEAD
AND DECREASED CLOUD COVER ACROSS THE AREA. SOME WEAK CONVERGENCE
AROUND 800 MB THIS MORNING...AND SOME GUIDANCE IS DEVELOPING
ELEVATED THUNDERSTORMS NEAR THIS BOUNDARY. WILL KEEP THINGS DRY IN
THE GRIDS FOR NOW...BUT WOULD NOT BE TOO SURPRISED IF WE END UP WITH
AN ISOLATED STORM OR TWO...BEST CHANCE SEEMS TO BE ALONG AND WEST OF
THE JAMES RIVER. TEMPERATURES ALOFT CONTINUE TO WARM...BUT GIVEN THE
INCREASING LOW LEVEL MOISTURE AND STRENGTHENING INVERSION...MIXING
SHOULD BE LESS EFFECTIVE TODAY. BUT BASED ON HOW WARM WE GOT
YESTERDAY...AND THE EXPECTED PARTLY TO MOSTLY SUNNY SKIES...DID BUMP
HIGHS UP A COUPLE DEGREES. THUS TODAY SHOULD SEE HIGHS IN THE MID
70S TO NEAR 80 FOR MOST OF US...WITH BLUSTERY SOUTHERLY WINDS
GUSTING 15 TO 30 MPH.

LOW LEVEL JET INCREASES TONIGHT WHICH WILL KEEP THINGS BLUSTERY.
ABUNDANT LOW LEVEL MOISTURE WILL ALSO ADVECT NORTH...AND SEEMS
LIKELY THAT LOW STRATUS WILL FORM OR MOVE IN AFTER MIDNIGHT. AT THIS
TIME THINK MOST OF THE MOISTURE WILL TRANSLATE INTO STRATUS AND NOT
NECESSARILY FOG...SO WILL STAY AWAY FROM MENTIONING FOG IN THE
GRIDS...BUT SOMETHING TO WATCH. DEEP MOISTURE MAY BE AN ISSUE...BUT
SEEMS LIKE WE COULD SEE ISOLATED THUNDERSTORMS AFTER 08Z OR SO ON
THE NOSE OF THE DEVELOPING 800 TO 850 MB JET. SO WILL KEEP LOW POPS
EAST OF INTERSTATE 29 TO ACCOUNT FOR THIS THREAT. LOWS WILL STAY
MILD...UPPER 50S TO MID 60S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 306 AM CDT THU SEP 18 2014

FRIDAY SHOULD PROVE TO BE MOSTLY DRY...BREEZY AND A BIT ON THE HUMID
SIDE. A FEW SHOWERS AND THUNDERSTORMS WILL EXIT THE FAR EASTERN CWA
IN THE MORNING...THEN THE REMAINDER OF THE DAY WILL SEE DECREASING
CLOUDS AHEAD OF AN INCOMING COOL FRONT. FRIDAY STILL LOOKS LIKE THE
WARMEST DAY WITH HIGHS LIKELY IN THE MID TO UPPER 80S IN MANY SPOTS.
THE FAR EASTERN CWA SHOULD END UP IN THE 80 TO 85 DEGREE RANGE AS
CLOUDS ARE A LITTLE SLOWER TO ERODE.

EARLY FRIDAY EVENING AN UPPER LEVEL WAVE WILL SWING THE FRONT
THROUGH THE AREA AND SHOULD IGNITE SCATTERED THUNDERSTORMS. AN
ISOLATED SEVERE STORM WILL BE POSSIBLE BUT NOT EXPECTED TO BECOME A
MAJOR PROBLEM. THE MOST WIDESPREAD COVERAGE WILL LIKELY BE OVER
NORTHWEST IOWA AFTER ABOUT 900 PM. STRONG WINDS AND HUMIDITY WILL
HELP KEEP LOWS IN THE 60S.

A WARM...MIXY AND BREEZY DAY SATURDAY AS NORTHWEST FLOW OVER TAKES
THE AREA. WHILE THE AIR MASS WILL BE COOLER THAN FRIDAY...STILL
LOOKING AT TEMPERATURES ABOVE NORMAL. HIGHS FROM THE UPPER 70S TO
LOWER 80S.

IN THE OUTER PERIODS (SUNDAY THROUGH WEDNESDAY)...MODELS STILL IN
FAIRLY GOOD AGREEMENT AND FAIRLY CONSISTENT WITH YESTERDAYS OUTPUT.
WHILE THE CANADIAN IS THE DEEPEST AND COOLEST WITH THE DEEPENING
UPPER LEVEL TROUGH TO THE NORTHEAST OF THE AREA...EACH MODEL HAS A
FAIRLY STRONG TROUGH WITH A DEVELOPING AND BIT STRONGER UPPER LEVEL
RIDGE OVER THE ROCKIES. THIS KEEPS THE AREA IN WEAKENING NORTHWEST
FLOW ALOFT AS THE RIDGE SHIFTS EASTWARD THROUGH THE PERIOD. EACH OF
THE MODELS CONTINUE TO ALSO BE REMARKABLY CONSISTENT IN SWINGING
THROUGH A BIT OF A CUT OFF LOW PRESSURE THAT ORIGINATES IN SOUTHERN
CALIFORNIA ON THE TAIL END OF AN UPPER LEVEL TROUGH. THAT LOW IS
PROGGED TO SPREAD INTO THE NORTHERN PLAINS TUESDAY INTO WEDNESDAY
AND SHOULD BRING INCREASING MID AND UPPER LEVEL MOISTURE INTO THE
AREA TUESDAY AND MORE SO WEDNESDAY. BEING A CUT OFF LOW AND EVEN WITH
MODEL CONSISTENCY NOT GOING TO INCLUDE ANY RAIN CHANCES JUST YET BUT
MAY NEED TO AT SOME POINT IN TIME FOR LATE TUESDAY INTO WEDNESDAY IF
TIMING REMAINS SIMILAR. OTHERWISE...DRY THROUGH THE PERIOD.
NORTHWEST FLOW AT THE SURFACE IN THE FIRST HALF OF THE PERIOD WILL
TURN SOUTHERLY IN THE SECOND HALF. OVERALL TEMPERATURES WILL
REMAIN NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1214 PM CDT THU SEP 18 2014

AREA IS PRIMED FOR WIDESPREAD STRATUS AND FOG DEVELOPMENT LATER
THIS EVENING AND OVERNIGHT. SHORT TERM MODEL GUIDANCE HANDLING
CURRENT TRAJETORY OF STRATUS NORTH INTO THE MISSOURI AND JAMES
RIVER VALLEY. THIS STRATUS SHOULD SLIDE EAST OVERNIGHT OVERTAKING
MUCH OF THE AREA BY DAYBREAK. INDICATIONS POINT TO MVFR TO IFR
CEILINGS WITH SLIGHT REDUCTIONS IN VISIBILITY. WOULD NOT RULE OUT
A BIT OF PATCHY DRIZZLE ESPECIALLY NEAR FSD/SUX TOWARDS DAYBREAK.

CEILINGS WILL STRUGGLE TO LIFT THROUGH FRIDAY MORNING.

&&

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

$$

SHORT TERM...CHENARD
LONG TERM...08
AVIATION...DUX



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