Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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898
FXUS63 KFSD 252107
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
407 PM CDT MON APR 25 2016

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 406 PM CDT MON APR 25 2016

DRYING IS SEEN IN THE SO FAR VERY SLOW THINNING OF CLOUDS AND LIFTING
OF CEILINGS...AND IN THE MISSOURI RIVER GETTING CLOSE TO CLEARING.
EXPECT THIS PROCESS TO ACCELERATE THIS AFTERNOON AND CONTINUE INTO
THE EVENING AS THE LINGERING SYSTEM FROM SUNDAY SLOWLY MOVES
FURTHER EAST OF THE AREA. PLENTY OF CLOUDS WILL LIKELY STAY NORTH OF
INTERSTATE 90 ALTHOUGH THEY WILL CONTINUE TO THIN OUT THIS EVENING
WHILE THE SOUTHERN PART OF THE AREA DOES A HALF DECENT JOB OF
CLEARING.

LATE TONIGHT UNDER THE WEAK BUT STILL EXISTING NORTHERLY FLOW...SOME
REDEVELOPMENT OF LOW CLOUDS IN THE NORTH IS LIKELY BUT NOT NEARLY TO
THE EXTENT WE HAD THEM THIS MORNING. WILL NOT PUT FOG IN FOR NOW
SINCE AM THINKING THERE WILL BE ENOUGH DRYING AND LINGERING FLOW TO
PRECLUDE FOG DEVELOPMENT. THIS MORNINGS LITTLE FOG EPISODE NORTH
AND NORTHWEST OF FSD WAS BASICALLY STRATUS LOWERING TO THE SURFACE.

LOW TEMPERATURES TONIGHT WILL BE IN THE 40S...NEAR 40 NORTHWEST TO
THE UPPER 40S SOUTHEAST...OR IN NORTHWEST IOWA.

TUESDAY WILL SEE INCREASING CLOUDS FROM THE SOUTHWEST...EXCEPT FOR
A POSSIBLE INITIAL DECREASE OF LOW CLOUDS THAT REDEVELOP NORTH/
NORTHEAST OF FSD LATE TONIGHT. A SHOWER THREAT SHOULD DEVELOP BY
LATE MORNING SOUTHWEST...IN THE 9V9/PKS AREA...AND SPREAD SLOWLY
NORTH AND EAST DURING THE DAY. THIS WILL BE AHEAD OF THE MAIN UPPER
SUPPORT WITH THE APPROACHING SYSTEM AND THAT IS THE REASON FOR THE
EXPECTED SLOW INCREASE. MODELS DO RAMP UP INSTABILITY COMING INTO
THE KSUX AREA NEAR THE END OF THE DAY BUT AGAIN THIS WILL BE AHEAD
OF THE MAIN UPPER SUPPORT...SO THE CHANCES WILL BE PRETTY SMALL.
NO MENTION IN SOUTHWEST MN AND IN MUCH OF NORTHWEST IA DURING THE
DAY. HIGH TEMPERATURES ARE EXPECTED TO VARY FROM THE 50S NORTH TO
THE 60S IN NORTHWEST IOWA...WHERE ENOUGH OF A BREAK BEFORE THE
CLOUDS THICKEN COULD BRING 70 PLUS. WINDS WILL STIFFEN SLOWLY
DURING THE DAY...POSSIBLY GETTING TO THE BREEZY CATEGORY IN THE
AFTERNOON. THE WINDS WILL START NORTHEASTERLY AND BECOME SOMEWHAT
MORE EASTERLY AS THEY SLOWLY INCREASE.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 406 PM CDT MON APR 25 2016

NEXT SIGNIFICANT UPPER LEVEL LOW WILL TAKE A TWO DAY TREK ACROSS THE
REGION...BUT ON A TRACK SOMEWHAT SOUTHWARD OF THIS LAST SYSTEM. THIS
SYSTEM WILL SEND THE FIRST LOBE OF ENERGY NORTHEAST INTO THE AREA
TUESDAY NIGHT. PRECIPITATION SHOULD BE INCREASING EARLY ON IN THE
PERIOD TOWARD SOUTH CENTRAL SD AND THE MISSOURI VALLEY WITH LEADING
MID LEVEL MOISTURE ADVECTION TOWARD LOCATION OF DEVELOPING INVERTED
TROUGH/DEFORMATION ZONE. THIS LOBE WILL CONTINUE TO WRAP NORTHWARD
AND FORCE CONVECTIVE DEVELOPMENT NORTH OF THE WARM FRONTAL BOUNDARY
SPREADING THROUGH THE ENTIRE CWA OVERNIGHT. SHOULD NOTE THAT THERE
IS POTENTIAL THAT SIGNIFICANT CONVECTION DEVELOPING WELL TO THE
SOUTH ACROSS SOUTHERN/EASTERN NEBRASKA MAY IMPACT INITIAL
DEVELOPMENT OF LESS SIGNIFICANT PRECIP TO THE NORTH...PERHAPS
SLOWING UP BY AS MUCH AS SEVERAL HOURS. ALSO...AN IMPACT OF THE
SOUTHWARD TRACK OF MAIN SYSTEM WILL BE TO LIMIT THE NORTHWARD EXTENT
OF SURFACE BASED INSTABILITY TO AREAS SOUTH OF THE CWA...AND TO
DIMINISH THE DEGREE OF ELEVATED INSTABILITY PUSHING NORTHWARD. WHILE
THE SHEAR LOOKS IMPRESSIVE AT FIRST LOOK FOR THE LOWER MISSOURI
VALLEY...THE EFFECTIVE SHEAR GIVEN THE DEEPER STABLE LAYER BELOW 875
HPA LAYER SUGGESTS THAT THREAT FOR EVEN AN ISOLATED HAILER IS
PRACTICALLY NIL.

WEDNESDAY WILL SEE INITIAL BAND CONTINUING TO LIFT NORTHWARD AS CORE
OF UPPER LOW STARTS TO STRETCH OUT ACROSS NEBRASKA. BY LATE DAY...
COMPOSITE OF SOLUTIONS SUGGESTS THAT NEXT SURGE OF LIFT CLOSER TO
CORE OF WAVE SHOULD GET GOING AND LIFT TOWARD THE LOWER MISSOURI
VALLEY TOWARD EVENING. ALWAYS DIFFICULT TO TIME THE INS AND OUTS OF
VARIOUS BANDS WITHIN THESE VERY WRAPPED UP SYSTEMS...BUT APPEARS
SHOULD GET TO AT LEAST A PARTIAL DOWNTIME IN COVERAGE WORKING
NORTHWARD INTO THE CWA BY LATER MORNING. WITH PERSISTENT DIV Q
ASSOCIATED WITH THE CONTINUED ADVECTIONS NORTH/EAST OF THE UPPER LOW
CENTER...HARD TO FULLY DROP CHANCES AT THIS POINT AT ANY TIME/PLACE.
AGAIN...THERE IS A FAIRLY NARROW PROFILE OF MAINLY ELEVATED
INSTABILITY IN PLACE THROUGH THE DAY AND INTO THE EVENING...WITH
GREATEST ELEVATED INSTABILITY VALUES PERHAPS 1000 J/KG...BUT USABLE
SHEAR REMAINS SMALL. SOME SMALL HAIL WOULD LIKELY BE TOP END OF ANY
THREAT THROUGH THE EVENING. CONVEYOR BELT OF MOISTURE/WEAK STABILITY
REMAINS BACKING THROUGH THE CWA TOWARD CENTRAL SD...AND WILL LIKELY
SEE BAND OF RAINFALL...GRADUALLY REDUCING IN INTENSITY/COVERAGE
THROUGH THE LATTER STAGES OF THE NIGHT.  BEFORE RAIN TAPERS DOWN IN
INTENSITY THURSDAY...MANY AREAS ARE LIKELY TO RECEIVE RAINFALL IN
EXCESS OF AN INCH OVER THE 36-48 HOURS PRIOR.

UPPER LOW CONTINUES TO ELONGATE THURSDAY SOUTH OF RIDGE HOLDING
PLACE TO THE NORTH OF THE REGION...WITH A PIECE SHEARING EAST OUT OF
THE AREA...AND REMAINDER OF THE TROUGH LIFTING NORTH THROUGH THE
NORTHERN HIGH PLAINS. UNFORTUNATELY THE MASS OF CLOUDS WILL LINGER
AS UPPER FEATURES GRADUALLY BECOME LESS FOCUSED FOR SHOWERS HEADING
THROUGH THURSDAY NIGHT. WILL START TO DRYING OUT PROCESS THU NIGHT
WITH A BIT DRIER NORTHEAST TRAJECTORY AT LOWER LEVELS...WHICH SHOULD
CONTINUE FRIDAY...AT LEAST UNTIL LEADING IMPACTS OF THE NEXT UPPER
LOW BRING THE PRECIP THREAT SLIGHTLY EASTWARD AGAIN LATE DAY. TEMPS
FROM WED THROUGH FRIDAY NOT LIKELY TO SHOW A GREAT DEAL OF DIURNAL
VARIABILITY.

NO REST FOR THE WEARY...AS ANOTHER UPPER WAVE WILL MOVE OUT OF THE
SOUTHWESTERN U.S. AND BACK INTO THE CENTRAL AND NORTHERN PLAINS OVER
THE WEEKEND. THE TRACK IS STILL UNCERTAIN...BUT MOST INDICATIONS ARE
A BIT TOWARD THE SOUTHWARD SIDE AS FOR THE WEDNESDAY SYSTEM. THIS
SHOULD KEEP THE SEVERE WEATHER THREAT LOW...BUT THREAT FOR ADDITIONAL
SOAKING RAINFALL IN PLAY. TEMPS WILL REMAIN ON THE COOL SIDE AS WELL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1235 PM CDT MON APR 25 2016

CEILINGS 1-3K FEET AT 18Z WILL IMPROVE FROM THE SOUTH TO VFR
THROUGH 26/00Z. AREAS OF CEILINGS 1-3K FEET REDEVELOPING NORTH OF
INTERSTATE 90 AFTER 25/08Z WITH LOCAL CEILINGS 3-5SM/BR FROM BKX
INTO SOUTHWESTERN MN. IMPROVEMENT TO VFR AGAIN EXPECTED 25/15Z-
18Z.

&&

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

$$

SHORT TERM...
LONG TERM...CHAPMAN
AVIATION...



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