Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 041037
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
537 AM CDT TUE AUG 4 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM CDT TUE AUG 4 2015

MAIN CONCERN IN THE SHORT TERM IS THE CHANCES FOR THUNDERSTORMS
THROUGH THE NEXT 24 H.

AS OF 08Z...A COMPLEX OF THUNDERSTORMS WAS ALONG THE 850 MB FRONT
FROM WEST CENTRAL SD TO SOUTH CENTRAL SD TO SOUTHEAST NEBRASKA.
WHILE A COUPLE OF STORMS MAY HAVE HAIL...THE MAIN CONCERN WITH THESE
STORMS IS HEAVY RAIN. EXPECTATION IS THAT THESE STORMS WILL PERSIST
THROUGH SUNRISE AND THEN WEAKEN AS A WAVE OVER COLORADO MOVES INTO
KANSAS. EXPECTATION IS THAT THIS WAVE WILL DECREASE INFLOW OF
MOISTURE AND WEAKEN THE WARM ADVECTION ALONG THE 850 FRONT AS LIFT
BEGINS TO FOCUS FARTHER SOUTH. THEREFORE...AM NOT EXPECTING THAT
STORMS TO REACH SIOUX CITY NOR WILL THEY GET TOO FAR NORTH OF THE
NEBRASKA AND SOUTH DAKOTA BORDER EAST OF GREGORY COUNTY. AFTER THIS
CONVECTION DISSIPATES THIS MORNING...MUCH OF THE FOCUS FOR ASCENT IS
REALLY ACROSS WESTERN NEBRASKA AND INTO KANSAS. SO HAVE ONLY A
SLIGHT CHANCE OF THUNDERSTORMS IN THE MISSOURI VALLEY ALONG THE
REMNANT BOUNDARY. SO WHILE THERE COULD BE AN ISOLATED STORM MOST OF
THE AREA SHOULD REMAIN DRY DURING THE DAY.

OTHERWISE...EXPECT PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE AREA
ONCE MORNING CONVECTION ENDS. WITH LITTLE PRECIPITATION
EXPECTED...HIGHS SHOULD BE IN THE 80S ACROSS THE AREA.

FOR TONIGHT...MODELS SHOW THE NORTHERN PORTION OF THE WAVE MOVING
INTO CENTRAL SD THIS EVENING AND INTO FAR EASTERN SD AND NEBRASKA BY
12Z WEDNESDAY. SO THERE WILL BE LARGE SCALE ASCENT PRESENT AND THERE
IS SOME INSTABILITY...ESPECIALLY SOUTH OF I90. THE CONCERN IS
MOISTURE RETURN. WITH THE FIRST WAVE MOVING ACROSS KANSAS...MOISTURE
RETURN WILL BE VERY LIMITED TODAY AND WHILE THERE IS A BETTER RETURN
FLOW TONIGHT...THE DELAY WILL LIMIT BOTH THE INSTABILITY AND
COVERAGE OF CONVECTION. IN FACT...HI-RES MODELS AS WELL AS THE NAM
ARE SHOWING MOST OF THE PRECIPITATION REMAINING IN NEBRASKA. EVEN
LOW RES MODELS ARE INDICATING THAT ANY PRECIPITATION IN SOUTHEAST
SOUTH DAKOTA AND NW IA WILL BE RATHER LIMITED. SO KEPT POPS  40
PERCENT OR LOWER AND ALSO SLOWED THE PROGRESSION OF ANY
PRECIPITATION CHANCE NORTH OF THE MISSOURI RIVER SUCH THAT AREAS
NORTH OF A HURON TO STORM LAKE LINE ARE DRY THROUGH MIDNIGHT. WITH
CLOUDS AND SOUTHEAST FLOW...LOWS WILL PRIMARILY BE IN THE 60S WITH A
FEW UPPER 50S IN SOUTHWEST MINNESOTA.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 344 AM CDT TUE AUG 4 2015

MADE SOME FAIRLY SIGNIFICANT CHANGES TO THE FORECAST FOR WEDNESDAY
AND WEDNESDAY NIGHT...LOWERING POPS FOR MUCH OF THE PERIOD. THE
SHORTWAVE SITUATED THROUGH CENTRAL NEBRASKA ON WEDNESDAY MORNING
WILL SLIDE INTO KANSAS AND MISSOURI BY LATE IN THE DAY. WITH MOST
OF THE CONVECTION FIRING TO OUR SOUTH...LIMITING MOISTURE RETURN
INTO OUR AREA...AND SUBSIDENCE BUILDING INTO THE AREA FROM WEST TO
EAST DURING THE DAY...THINK THAT AFTER SMALL CHANCES OF SHOWERS AND
THUNDERSTORMS THROUGH THE MORNING THAT CHANCES WILL DECREASE IN THE
AFTERNOON. AFTER THAT...EXPECT MOST OF WEDNESDAY NIGHT TO BE DRY.
WITH A LESSER CHANCE OF SHOWERS ON WEDNESDAY THAN
PREVIOUSLY...GUIDANCE COMING IN WARMER...SO RAISED HIGHS A COUPLE OF
DEGREES TO MAINLY LOWER TO MID 80S.

ON THURSDAY ANOTHER SHORTWAVE SLIDES OUT OF THE NORTHERN ROCKIES
DURING THE DAY...AND WHILE THERE ARE SUBTLE MODEL DIFFERENCES IN
HANDLING THIS WAVE...CONSENSUS BRINGS A DECENT CHANCE OF SHOWERS AND
THUNDERSTORMS TO THE AREA BY THURSDAY AFTERNOON AND EVENING. MODEL
CONVECTIVE PARAMETERS DIFFER A BIT...BUT CANNOT RULE OUT A STRONG TO
ISOLATED SEVERE STORM LATE THURSDAY AFTERNOON/EVENING WITH
INSTABILITY/INCREASING SHEAR AS THE SHORTWAVE TRACKS OVERHEAD AND A
SURFACE TROUGH/FRONTAL BOUNDARY SLIDES ACROSS THE AREA DURING THAT
TIME FRAME. THURSDAY HIGHS ONCE AGAIN LOOK TO BE LOWER TO MID
80S...POSSIBLY SOME UPPER 80S THROUGH SOUTH CENTRAL SD.

FRIDAY WILL BE DRIER AS THE SYSTEM PULLS AWAY. IT WILL ALSO BE
SLIGHTLY COOLER IN A NORTH/NORTHEASTERLY LOW LEVEL FLOW WITH HIGHS
UPPER 70S TO LOWER 80S.

FARTHER INTO THE EXTENDED...OUR AREA REMAINS IN A NORTHWESTERLY
UPPER LEVEL FLOW WITH AN UPPER LEVEL RIDGE SITUATED OVER THE
ROCKIES/HIGH PLAINS. THERE WILL BE PERIODIC PRECIPITATION CHANCES
INTO THE BEGINNING OF NEXT WEEK AS VARIOUS SHORTWAVES SLIDE ACROSS
THE REGION. AS IT IS TYPICAL IN THE EXTENDED...THERE IS LOW
CONFIDENCE IN THE TIMING OF THESE WAVES. TEMPERATURES THROUGH THE
PERIOD WILL PLAY OUT TO NEAR NORMAL WITH HIGHS LOWER/MID 80S AND
LOWS LOWER/MID 60S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 537 AM CDT TUE AUG 4 2015

CONVECTION FROM SOUTH CENTRAL SD INTO EAST CENTRAL NEBRASKA IS
EXPECTED TO REMAIN SOUTH OF KSUX THIS MORNING. ONLY AFFECT WILL BE
HIGH CLOUDS. THERE IS A SMALL CHANCE OF THUNDERSTORMS IN KSUX FROM
LATE THIS AFTERNOON INTO WEDNESDAY MORNING. WITH SUCH A LOW THREAT
AND BEING UNABLE TO RESTRICT TIMING TO A 2 TO 4 HOUR WINDOW...HAVE
NOT INCLUDED IN TAF FOR KSUX. FOR KHON AND KFSD...CHANCE FOR
STORMS IS CONFINED TO AFTER 06Z WEDNESDAY BUT THIS CHANCE IS SMALL
AND WILL NOT INCLUDE IN TAF AT THIS TIME.

OTHERWISE...VFR CONDITIONS ARE EXPECTED THROUGH 12Z WEDNESDAY.

&&

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

$$

SHORT TERM...SCHUMACHER
LONG TERM...JM
AVIATION...SCHUMACHER



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