Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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718
FXUS63 KFSD 261124
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
624 AM CDT TUE APR 26 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 402 AM CDT TUE APR 26 2016

WHILE MUCH OF TODAY WILL PROVE TO REMAIN DRY...ESPECIALLY EAST OF
THE JAMES RIVER...RAIN AND THUNDERSTORMS WILL MOVE BACK INTO THE
AREA TONIGHT. A FAIRLY POTENT CLASH OF AIR MASSES IS TAKING PLACE
ACROSS PARTS OF KANSAS AND NEBRASKA EARLY THIS MORNING AND AS LOW
PRESSURE ACROSS COLORADO LIFTS NORTHEAST THIS AFTERNOON AND TONIGHT
SOUTH TO SOUTHEAST WINDS ALOFT WILL INCREASE...ADVECTING THIS MORE
UNSTABLE AIR MASS NORTHWARD. WHILE THE LOW LEVELS...MAINLY BELOW
850MB...WILL REMAIN FAIRLY STABLE THE 800MB TO 700MB LAYER MAY
PROVIDE THE AREA WITH SOME DECENT INSTABILITY...ESPECIALLY AFTER
20Z. THIS SHOULD START TO BRING THE INCREASE IN SHOWER AND
THUNDERSTORM POTENTIAL INTO THE AREA. THE CHALLENGE FOR ELEVATED
THUNDERSTORMS LATE AFTERNOON AND EARLY EVENING WILL BE A DRY LAYER
IN THAT IMPORTANT 800MB TO 600MB LAYER. THE MODELS ARE NOT REAL
CONSISTENT ON THE AMOUNT OF MOISTURE THAT WILL ADVECT NORTH...WHICH
IS IMPORTANT TO AID IN BREAKING THE CAP...BUT MOST ARE FAIRLY
AGREEABLE THIS MOISTURE WILL AT LEAST COME CLOSE TO BREAKING THE
CAP...SO WILL HAVE SOME MID RANGE POPS FOR THIS AFTERNOON AND
EVENING. AT THIS TIME NOT PLANNING ON ANY SEVERE THREAT WITH THIS
ACTIVITY. AFTER ABOUT 3Z THE MAIN WAVE WILL LIFT NORTH AND MOISTURE
AND INSTABILITY WILL LIFT NORTH SO EXPECTING WIDESPREAD RAIN AND
SCATTERED THUNDERSTORMS. MODERATE TO OCCASIONAL HEAVY RAIN WILL
BRING A GOOD CHANCE FOR A HALF AN INCH TO AN INCH OF RAIN TO AREAS
ALONG AND SOUTH OF A DE SMET TO IDA GROVE LINE BY SUNRISE WEDNESDAY
MORNING.

AS FOR TEMPERATURES WILL KEEP THE PRETTY COOL WHERE CONFIDENCE IN
STRATUS IS HIGHEST TODAY...MAINLY MID 50S...WHILE PARTS OF NORTHWEST
IOWA SHOULD REACH THE UPPER 60S WITH SOME SUNSHINE. STAYED CLOSEST
TO THE PREVIOUS FORECAST AND CONSRAW FOR LOWS TONIGHT WITH STRONG
EASTERLY FLOW. THE ONLY OFFSET TO REMAINING VERY MILD IS THE THREAT
FOR MODERATE TO HEAVY RAIN WHICH SHOULD LOWER TEMPERATURES MORE THAN
IF THERE WAS NO RAIN.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 402 AM CDT TUE APR 26 2016

WEDNESDAY CONTINUES TO LOOK VERY WET AS UPPER LEVEL LOW MOVES FROM
CENTRAL KANSAS INTO SOUTHERN IOWA. BOTH THE NAM AND GFS SUGGEST
FORECAST AREA WILL BE ON THE NORTHERN EDGE OF MOIST TONGUE
EXTENDING FROM THE GULF NORTHWARD WITH OVER AN INCH OF PRECIPITABLE
WATER.  AS UPPER LOW BREAKS APART AND ONE PIECE OF ENERGY MOVES EAST
AND THE OTHER LIFTS TO THE NORTH AND WEST...EXPECT WIDESPREAD
PRECIPITATION FOCUS TO GRADUALLY LIFT NORTH THROUGHOUT THE DAY. BOTH
NAM AND GFS SUGGEST THE POTENTIAL FOR THUNDERSTORMS TO DEVELOP AT
LEAST THROUGH THE MORNING HOURS ACROSS THE SOUTHERN EDGE OF THE
FORECAST AREA WITH UNCAPPED ENVIRONMENT ORIGINATING FROM ELEVATED
INVERSION NEAR 850 HPA. EXPECT THUNDER POTENTIAL TO GRADUALLY WANE
THROUGH THE OVERNIGHT HOURS WEDNESDAY NIGHT. WITH RAIN EXPECTED
THROUGH MUCH OF THE DAY...HAVE COOLED FORECAST HIGHS AND SQUASHED
DIURNAL RANGE.

ON THURSDAY...MODELS SHOW THE POTENTIAL FOR LINGERING SHOWERS ACROSS
THE AREA...BUT THERE IS NO CONSISTENCY AS TO WHERE.  NAM SOUNDINGS
ALONG AND WEST OF THE JAMES SHOW INSTABILITY DEVELOPING IN THE 900-
800 MB LAYER RESULTING IN INSTABILITY SHOWERS AND THUNDERSTORMS
DEVELOPING...WHILE THE GFS IS MUCH FURTHER SOUTH AND EAST NEAR
SOUTHERN IOWA WITH ANY INSTABILITY. FOR NOW...STUCK CLOSE TO
GUIDANCE POPS FOR NOW.

REALLY TRENDED DOWN ON POPS FRIDAY AS AREA APPEARS TO BE TEMPORARILY
VOID OF ANY UPPER LEVEL FORCING ACROSS THE REGION.  HAVE SOME SLIGHT
CHANCE POPS IN CENTRAL SOUTH DAKOTA...BUT THERE IS DECENT POTENTIAL
TO EVEN PULL THOSE AS MODELS ARE SLOWING SECOND SYSTEM.

ANOTHER UPPER LEVEL LOW IS EXPECTED TO IMPACT THE REGION THROUGH THE
WEEKEND.  THIS SYSTEM LOOKS TO BE FOCUSED SLIGHTLY FURTHER
SOUTH...AND AT THIS POINT DOESN/T LOOK TO PRODUCE AS MUCH
PRECIPITATION ACROSS THE AREA AS THE MID WEEK SYSTEM WILL.
HOWEVER...BOTH SYSTEMS BECOME CUT OFF...RESULTING IN COOL DAMP
WEATHER THROUGH MUCH OF THE EXTENDED. HAVE RAISED POPS WITH THE
SECOND SYSTEM...ESPECIALLY ON SATURDAY INTO SATURDAY NIGHT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 622 AM CDT TUE APR 26 2016

MVFR CEILINGS OVER MUCH OF THE AREA THIS MORNING MAY LIFT TO LOW
END VFR CEILINGS FOR A BIT THIS AFTERNOON...BUT AS RAIN AND
THUNDERSTORMS MOVE NORTH CONDITIONS WILL AGAIN DETERIORATE THIS
EVENING AND OVERNIGHT. MVFR TO IFR CONDITIONS MOST LOCATIONS AFTER
3Z ALONG WITH THE RAIN AND THUNDERSTORMS. BETTER CHANCE FOR
STRONGER THUNDERSTORMS WILL BE SOUTH OF INTERSTATE 90.

&&

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

$$

SHORT TERM...08
LONG TERM...BT
AVIATION...08



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