Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 291726
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1226 PM CDT FRI MAY 29 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 413 AM CDT FRI MAY 29 2015

BROAD UPPER TROUGHING ACROSS THE NORTHERN AND CENTRAL PLAINS...WITH
NORTHERN STREAM ENERGY NEAR THE CANADIAN BORDER...AND MAIN SOUTHERN
ENERGY HANGING BACK ACROSS NORTHERN COLORADO. THE BROAD TROUGH IS
LITTERED WITH SMALLER SCALE DISTURBANCES AND BOUNDARIES...LEADING TO
WHAT IS A FAIRLY LOW CONFIDENCE ON TIMING OF PRECIPITATION THREAT
FOR TODAY. HAVE NO LESS THAN THREE WAVES IN/NEAR THE CWA AT 08Z...
ONE NEAR DOUGLAS COUNTY...ANOTHER SOUTHWEST OF BROOKINGS...AND A
THIRD NEAR AURORA NEBRASKA. EACH HAVE BEEN LIFTING NORTHEAST AND
ENHANCING SMALLER AREAS OF CONVECTION AHEAD. STRONGEST OF THE THREE
IS THE LATTER...AND THIS WILL BE STREAMING NORTHEAST ACROSS
NORTHWEST IOWA IN THE PREDAWN HOURS. PRECIP SHOULD BE QUICKER TO
DEVELOP AND SPREAD NORTHEAST DURING THIS TIME...AND ALSO QUICKER TO
DISSIPATE.  WITH THE OVERALL WEAKER FLOW...NOT A WONDER THAN HIGH
RESOLUTION MODELS ARE OFF ON PREDICTING THE IMMEDIATE TERM...BEING
MUCH TOO SLOW GETTING ACTIVITY GOING...AND SEEMINGLY ENTRANCED ON
QUICKLY SOUTHWARD PUSHING COLD FRONT BY EARLY TO MID MORNING. WOULD
EXPECT THAT FRONT WILL BECOME MORE ACTIVE THROUGH THE DAY...BUT
BETTER SHARE OF THIS MIGHT NOT OCCUR UNTIL AT LEAST THE MIDDAY TO
AFTERNOON HOURS. CURRENTLY IS SOME SCATTERED ACTIVITY NEAR THIS
BOUNDARY FROM SOUTHEAST NORTH DAKOTA BACK TO CENTRAL SOUTH DAKOTA.
ATMOSPHERE IS CERTAINLY JUST TO THE UNSTABLE SIDE OF NEUTRAL AHEAD
OF THIS BOUNDARY...SO AS FORCING FROM THE LARGER SCALE TROUGHING AND
FRONTAL BOUNDARY PUSHES IN...THERE IS LITTLE TO PREVENT ADDITIONAL
CONVECTION FROM DEVELOPING. AS A RESULT...WILL BE UNABLE TO BOTTLE
UP MUCH POTENTIAL INSTABILITY...AND NOT MUCH CHANCE THAT STORMS
WOULD BECOME SEVERE TODAY...EVEN IN SOUTHEAST WHERE HAVE THE
GREATEST TIME IN PREFRONTAL ENVIRONMENT AND LARGEST POTENTIAL FOR
GREATEST SURFACE WARMING.  WOULD HAVE TO KEEP A WATCHFUL EYE ON
RAINFALL THOUGH...AS EVEN SMALLER STORMS TONIGHT WERE SHOWING
INSTANTANEOUS RATES OF 1-2 INCHES/HR.

MAX TEMPS TODAY COULD BE REACHED FAIRLY EARLY IN THE DAY ACROSS THE
NORTHERN CWA...AS STRONG LOW LEVEL COLD AIR ADVECTION PUSHES IN
BEHIND THE BOUNDARY...STARTING AS EARLY AS 15Z IN THE MID JAMES
VALLEY.

TONIGHT...WILL SEE SOME LINGERING SHOWERS AND PERHAPS A RUMBLE OF
THUNDER ACROSS NORTHWEST IOWA...BUT SHOULD EXIT AS DRIER AIR WORKS
TO UNDERCUT THE UPPER LEVEL SYSTEM SHEARING PAST. PRECIPITATION
SHOULD GRADUALLY WORK TO FAVOR AREAS NEARER THE LOWER LEVEL
INSTABILITY BY LATE AFTERNOON/EARLY EVENING...WHICH WILL REFOCUS MAX
POTENTIAL QUICKLY SOUTHEAST OF THE CWA. WHILE DO EXPECT CLOUDS TO
REMAIN MUCH OF THE NIGHT OVER THE SOUTHEAST HALF...WILL WORK SOME
CLEARING INTO THE NORTHWEST...AND THE STRONG COLD ADVECTION WILL
ALLOW SOME TEMPS DOWN CLOSE TO 40 DEGREES NORTHWEST...TO NEAR 50
SOUTHEAST.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 413 AM CDT FRI MAY 29 2015

IN GENERAL...THIS UPCOMING WEEKEND LOOKS LIKE A VERY PLEASANT ONE.
SFC HIGH PRESSURE WILL MOVE INTO THE LOWER 48 EARLY ON SATURDAY.
BRINGING SLIGHTLY BELOW NORMAL TEMPERATURES AND RATHER LIGHT WINDS
ON SATURDAY.  BY SUNDAY...A WEAK SHORTWAVE WILL BEGIN TO MOVE INTO
THE PLAINS...EFFECTIVELY TURNING WINDS TO THE SOUTH. AFTER A COOL
OVERNIGHT PERIOD...HIGHS ON SUNDAY WILL FIND THEMSELVES NEAR 70
DEGREES.

THE PATTERN SETTING UP FOR NEXT WEEK AND INTO NEXT WEEKEND REMAINS
AN UNSETTLED ONE. MID-LVL HEIGHTS WILL TRY TO BUILD THROUGH THE
WEEK...BUT WILL REALLY NEVER BECOME HIGH ENOUGH TO FORCE CONVECTION
NORTH OF THE CWA.  THERE WILL LIKELY BE DAILY RAIN CHANCES...MOST
LIKELY OF THE NOCTURNAL NATURE...AS A MYRIAD OF SHORTWAVES TOPS THE
SUPPRESSED RIDGE THROUGH THE WEEK. DAILY SEVERE WEATHER CHANCES WILL
CONTINUE TO BE ON THE LOW SIDE...GIVEN WEAK FLOW ALOFT...AND THE
CHANCES THAT RAIN WILL BE WIDESPREAD AT ANY GIVEN POINT IN TIME ARE
ON THE LOW SIDE. HOWEVER...THE WEAK FLOW ALOFT ALSO MEANS THAT IT
COULD BE DIFFICULT FOR THE PATTERN TO SHIFT OR CHANGE INTO NEXT
WEEKEND.

HIGH TEMPERATURES THROUGH NEXT WEEK WILL BE WARMER THAN
NORMAL...RUNNING ON AVERAGE 5 TO 10 DEGREES ABOVE THE CLIMATOLOGICAL
VALUES...WITH HIGHS AROUND THE 80 DEGREE MARK SEVERAL DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1227 PM CDT FRI MAY 29 2015

FREQUENT TO WIDESPREAD CEILINGS 1-3K FEET. SCATTERED SHOWERS WITH
LOCAL AND BRIEF VISIBILITY 3-5SM WILL END FROM THE NORTHWEST
18Z-30/03Z. TSRA POSSIBLE SUX/SLB AND SOUTHEAST UNTIL 30/00Z.
30/00Z-12Z CEILINGS WILL CLEAR TO VFR FROM THE NORTH WITH VFR
CONTINUING 30/12Z-18Z. SURFACE GUSTS AROUND 25 KNOTS FROM THE
NORTH THROUGH 30/03Z.

&&

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

$$

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


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