Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 301730
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1230 PM CDT THU APR 30 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 402 AM CDT THU APR 30 2015

SURFACE HIGH PRESSURE ACROSS THE AREA WILL SHIFT EAST
ALLOWING SOUTHERLY WINDS TO INCREASE...ESPECIALLY WEST OF I-29.
WITH SOUTHERLY FLOW SEE A MEAGER INCREASE IN MID LEVEL
MOISTURE...WHICH SHOULD LIMIT THE REDUCTION OF DEW POINTS DURING
PEAK HEATING.  ACROSS THE EASTERN HALF OF THE FORECAST AREA...WINDS
WILL BE SOMEWHAT LIGHT THROUGH MUCH OF THE DAY.  TEMPERATURES DID
NOT GET AS WARM AS EXPECTED YESTERDAY DUE TO LIGHT WINDS LIMITING
MIXING...AND EXPECT THE SAME TODAY ACROSS THE EAST.

WITH INCREASING WINDS...WILL SEE AN ELEVATED FIRE DANGER ACROSS
CENTRAL SOUTH DAKOTA.  AM NOT GOING TO ISSUE ANY FIRE WEATHER
HEADLINES AT THIS TIME...AS ONLY 20 KNOTS AT BOTH 925 AND 850 HPA
MAY KEEP FREQUENT GUSTS JUST SHY OF 25 MPH.

FOR TONIGHT...COLD FRONT WILL MOVE THROUGH THE AREA...THOUGH LIMITED
MOISTURE REALLY LIMITS INSTABILITY AND THUS PRECIPITATION POTENTIAL.
UPPER WAVE WILL ENCOUNTER DEEPER MOISTURE AS IT WORKS EAST ACROSS
THE AREA...AND EXPECT DEVELOPMENT BETWEEN THE JAMES RIVER VALLEY AND
THE I-29 CORRIDOR.  WITH WAVE SHEARING OUT ACROSS THE SOUTHERN
CWA...LIMITED FORCING BUT FURTHER TO THE NORTH...BETTER DYNAMICS TO
RESULT IN POTENTIAL FOR SHOWERS TO DEVELOP.  AS MENTIONED
EARLIER...VERY LIMITED AMOUNTS OF INSTABILITY...BUT COULD HAVE A
ROGUE LIGHTNING STRIKE OR TWO.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 402 AM CDT THU APR 30 2015

ON FRIDAY...THE SHORT WAVE WILL CONTINUE TO PRESS EAST AND
SOUTHEASTWARD AND WILL BE WELL EAST OF THE FORECAST AREA BY MID
AFTERNOON. THE ASSOCIATED SURFACE WIND SHIFT GETS HUNG UP AND STALLS
ITS SOUTHERN PROGRESS IN EXTREME NORTHWEST IA. IN THE MORNING...
LIKELY POPS ARE WARRANTED OVER SOME OF OUR EASTERN AND MOST OF OUR
SOUTHEAST ZONES AS FINALLY SOME LOW LEVEL MOISTURE BEGINS TO GEN UP
IN THE 850-800MB LAYER. RAIN AMOUNTS WILL NOT BE HEAVY HOWEVER. IN
THE EARLY MID AND AFTERNOON...MAY HAVE SOME SCATTERED SHOWERS
LINGERING ALONG AND SOUTH OF A SIOUX CITY TO SPENCER IA LINE BEFORE
THOSE LOCATIONS BEGIN TO CLEAR OUT BY LATE AFTERNOON. OTHERWISE
OVERALL A PRETTY NICE DAY IS IN STORE FOR MANY AREAS BY AFTERNOON...
WITH HIGHS IN THE 70S COUPLED WITH DECREASING WINDS AS THE AFTERNOON
PROGRESSES DUE TO THE STALLED WIND SHIFT LINE.

FRIDAY NIGHT IS A BIT INTERESTING CLOSE TO THE SIOUX CITY AND STORM
LAKE AREAS. THE VARIOUS MODELS SHOW A LOW LEVEL JET ARCING
NORTHEASTWARD THROUGH THE CENTRAL PLAINS WITH GOOD SPEED CONVERGENCE
IN EASTERN AND SOUTHERN NEBRASKA. BELIEVE THAT THERE IS NOT ENOUGH
CONVERGENCE TO WARRANT A SMALL POP IN OUR EXTREME SOUTHERN ZONES AT
THIS TIME BUT IT WILL BE CLOSE. FURTHERMORE THE STEERING WINDS IN
THE MID LEVELS POINT TO AN EAST TO SOUTHEASTWARD MOVEMENT OF ANY
CONVECTIVE DEVELOPMENT. SO IF SOME CONVECTION DOES DEVELOP TO OUR
SOUTH...IT WILL LIKELY NOT MOVE NORTHEASTWARD INTO OUR AREA.

SATURDAY WILL BE VERY WARM WITH HIGHS IN THE UPPER 70S TO MID 80S
USHERED IN BY A SOUTHERLY FLOW OF AIR. OUR FORECAST AREA IS MORE OR
LESS ON THE NOSE OF A LOW LEVEL JET WITH LITTLE IN THE WAY OF MIXED
LAYER INHIBITION. SO WOULD NOT RULE OUT SOME ISOLATED SKITTISH
CONVECTION HERE AND THERE SATURDAY AND SATURDAY NIGHT...BUT
CERTAINLY NOTHING SCATTERED LET ALONE WIDESPREAD.

THIS BEGINS TO CHANGE SUNDAY AFTERNOON AND EVENING AS A SHORT WAVE
MOVES EASTWARD AND USHERS THROUGH A COLD FRONT. MID LEVEL WINDS ARE
NOT REAL STRONG...BUT DECENT AT 35 TO 40 KNOTS. JUST AHEAD OF THE
FRONT...THERE IS CERTAINLY ENOUGH WIND SHEAR THAT THERE WILL LIKELY
BE A MARGINAL RISK OF SEVERE STORMS INITIALIZING IN EAST CENTRAL SD
AND MOVING EAST AND SOUTHEASTWARD FROM THERE. PERHAPS BY THE TIME
THE CONVECTION GETS INTO NORTHWEST IA BY EARLY EVENING...WOULD NOT
RULE OUT A SLIGHT RISK OF SEVERE WEATHER BY THAT TIME BUT IT DOES
NOT LOOK LIKE ANY SORT OF A WIDESPREAD EVENT. COULD BE SOME DECENT
RAINFALL HOWEVER ESPECIALLY IN SOUTHWEST MN AND NORTHWEST IA. HIGHS
ON SUNDAY ARE RATHER TRICKY DUE TO THE TIMING OF THE WIND SHIFT. AT
ANY RATE IT WILL BE WARM...BUT HOW WARM. FOR NOW KEPT MY NEVER
ENDING TREND OF LOADING BIAS CORRECTED TEMPERATURES WHICH RAISED
SUPERBLEND HIGHS A CATEGORY OR TWO.

BY EARLY NEXT WEEK...MOST OF THE RAINFALL CHANCES WILL PROBABLY BE
BOTTLED UP ALONG AND SOUTH OF INTERSTATE 90 AS THOSE LOCATIONS ARE
CLOSEST TO AN 850MB WARM FRONT WHICH RESIDES BETWEEN SIOUX CITY AND
OMAHA. IF THE GFS PANS OUT CLOSER THAN THE ECMWF...VERY LITTLE
RAINFALL WILL EXIST IN OUR FORECAST AREA MONDAY AND MONDAY NIGHT AS
THE WARM FRONT IS FURTHER SOUTH. BUT ALL MODELS ARE SHOWING STRONG
UPPER TROUGHING DEVELOPING OVER THE SOUTHERN ROCKIES AND LIFTING
NORTHWARD TUESDAY AND WEDNESDAY. SO CONDITIONS LOOK WET FOR A CHANGE
DURING THE MIDDLE OF NEXT WEEK...PERHAPS FROM TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT WITH SHORT WAVE ENERGY LIFTING NORTHWARD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1230 PM CDT THU APR 30 2015

VFR CONDITIONS EXPECTED TO DOMINATE THROUGH THE PERIOD. GUSTY
SOUTHERLY WINDS WILL PREVAIL IN AREAS WEST OF I-29 THROUGH THE
AFTERNOON...DIMINISHING AFTER SUNSET THIS EVENING. SURFACE FRONT
WILL MOVE EAST ACROSS THE REGION AFTER MIDNIGHT TONIGHT...FOLLOWED
BY A PERIOD OF SCATTERED SHOWERS. EXACT TIMING OF THE SHOWERS IS
UNCERTAIN...BUT HAVE ADDED 2-3 HOUR MENTION FOR WHAT CURRENTLY
APPEARS TO MOST FAVORABLE TIMES FOR PRECIPITATION AT OUR TAF
LOCATIONS. FORECAST SOUNDINGS SHOW VERY LIMITED INSTABILITY...SO
JUST AN ISOLATED THUNDER THREAT AT BEST AND WILL NOT INCLUDE IN
TAFS.

&&

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

$$

SHORT TERM...
LONG TERM...MJ
AVIATION...JH


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