Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 012018
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
318 PM CDT FRI AUG 1 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 317 PM CDT FRI AUG 1 2014

AN UPPER LEVEL WAVE WILL MOVE SOUTHEAST FROM NORTH DAKOTA INTO
CENTRAL SOUTH DAKOTA BY MIDNIGHT. THERE HAS BEEN AT LEAST ISOLATED
CONVECTION WITH THIS WAVE MOST OF THE DAY. WITH LAPSE RATES EXPECTED
TO BE AROUND 7 C/KM OVERNIGHT...WILL HAVE 200 TO 400 J/KG BASED
ABOVE 800 MB AS THIS WAVE MOVES IN. SO AM EXPECTING ISOLATED TO
SCATTERED ELEVATED CONVECTION TO DEVELOP IN CENTRAL SD AND THEN
SPREAD SOUTHEAST OVERNIGHT. HAVE RAISED POPS TO 30 PERCENT FROM
AFTER MIDNIGHT INTO SATURDAY MORNING IN THE MISSOURI VALLEY
INCLUDING SIOUX CITY. WITH THE WAVE EXPECTED TO MOVE INTO NE AND
WEST CENTRAL IOWA...DO NOT EXPECT CONVECTION TO GET AS FAR EAST AS
SOUTHWEST MINNESOTA AND SPENCER IOWA. THERE COULD ALSO BE SOME LIGHT
FOG TOMORROW AROUND SIOUX CITY AND INTO NORTHWEST IOWA. AM A LITTLE
MORE UNCERTAIN ABOUT THE FOG GIVEN LOWER DEW POINTS THIS AFTERNOON
SO DID NOT INCLUDE IN THE FORECAST. LOWS OVERNIGHT WILL BE AROUND 60
ACROSS THE AREA.

AS MENTIONED ABOVE...THE UPPER LEVEL WAVE WILL MOVE ACROSS THE MID
MISSOURI VALLEY IN THE MORNING BRINGING A CHANCE OF THUNDERSTORMS.
THESE STORMS ARE EXPECTED TO MOVE INTO SOUTHEAST NEBRASKA AND
SOUTHERN IOWA BY EARLY AFTERNOON WITH SKIES BECOMING PARTLY TO
MOSTLY SUNNY. WITH INCREASING SOUTH FLOW AND A BUILDING UPPER
RIDGE...WARMER AIR WILL SLOWLY MOVE EAST WITH HIGHS REACHING THE 80S
ACROSS THE AREA.  AROUND CHAMBERLAIN...A FEW LOCALES COULD REACH 90
DEGREES.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 317 PM CDT FRI AUG 1 2014

SATURDAY NIGHT WILL SEE MARGINAL INSTABILITY AND LAPSE RATES ALOFT
WHICH WILL SUPPORT THE STANDARD NOCTURNAL WEAK SHOWER AND
THUNDERSTORM THREAT. THIS SHOULD CONTINUE INTO SUNDAY BUT AGAIN
REMAIN PRETTY ISOLATED. NOT EXPECTING ANYTHING SEVERE. LOWS ON
SATURDAY NIGHT IN THE LOWER 60S WITH HIGHS ON SUNDAY POSSIBLY A BIT
HOT IN THE WESTERN CWA...FROM ABOUT 90 TO 95 WHILE THE EASTERN CWA
WILL BE ABOUT 80 TO 85.

SUNDAY NIGHT INTO MONDAY WILL SEE A MINOR THREAT FOR SHOWERS AND
THUNDERSTORMS...MAINLY OVER THE FAR EASTERN AND NORTHERN CWA.
AGAIN...NOTHING SEVERE. SIMILAR LOWS AND HIGHS TO SATURDAY NIGHT
INTO SUNDAY.

MONDAY NIGHT WILL SEE A SLIGHTLY STRONGER WAVE MOVE THROUGH THE FAR
NORTHERN PLAINS WHICH WILL BRING AN INCREASED THREAT FOR SHOWERS
AND THUNDERSTORMS...BUT BETTER CHANCES STILL LOOK TO COME ON TUESDAY
AND WEDNESDAY. BETTER CHANCES AGAIN OVER THE NORTHERN AND EASTERN
CWA. LOWS ON MONDAY NIGHT IN THE MID TO UPPER 60S.

IN THE OUTER PERIODS(TUESDAY THROUGH FRIDAY)...UPPER LEVEL RIDGING
OVER THE ROCKIES WILL BATTLE TROUGHING ACROSS SOUTHERN CANADA
THROUGH THE PERIOD. THE MODELS HAVE BEEN CONSISTENTLY INCONSISTENT
DURING THIS TIME FRAME AND WILL LIKELY CONTINUE TO DO SO AS THE
MODELS TRY TO RESOLVE THE ENERGY OVER SOUTHERN CANADA. WILL KEEP
POPS IN THE 50 TO 70 PERCENT RANGE FOR TUESDAY NIGHT INTO WEDNESDAY.
STILL EXPECTING A DECENT LOW LEVEL BOUNDARY WITH WHAT LOOKS TO BE A
PRETTY DECENT WAVE DURING THIS TIME. THURSDAY INTO FRIDAY
PRECIPITATION CHANCES WILL DECREASE BUT CONFIDENCE NOT REAL WILL
WITH THE ABOVE MENTIONED INCONSISTENCIES. AS FOR TEMPERATURES WILL
LIKELY KEEP THINGS ON THE COOL SIDE. THE ECMWF VALUES ARE COOLER
THAN THE GFS VALUES THROUGH THIS PERIOD AND WITH MEN TEMPERATURES
LOWER THAN MEX TEMPERATURES...WHICH ARE ALREADY BELOW
CLIMATOLOGY...THERE IS A PRETTY GOOD STATISTICAL SIGNAL TO REMAIN ON
THE COOL SIDE AS WELL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 110 PM CDT FRI AUG 1 2014

FOR KHON AND KFSD VFR CONDITIONS ARE EXPECTED THROUGH 18Z
SATURDAY. IN SIOUX CITY...WITH LIGHT ESE WINDS...EXPECT SOME LIGHT
FOG TO FORM TOWARD SUNRISE...AND IT SHOULD BURN OFF BY 14Z.

ONLY OTHER CONCERN IS THE POTENTIAL FOR CONVECTION LATE TONIGHT
AND SATURDAY MORNING. EXPECTATION IS THAT STORMS WILL BE FAIRLY
ISOLATED AS THE MOVE FROM CENTRAL SD AROUND MIDNIGHT AND TOWARD
KFSD AND KSUX AFTER SUNRISE. BECAUSE OF THE LOW PROBABILITY DID
NOT INCLUDE IN TAF AT THIS TIME.

&&

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

$$

SHORT TERM...SCHUMACHER
LONG TERM...08
AVIATION...SCHUMACHER






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