Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 111143
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
643 AM CDT FRI JUL 11 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 416 AM CDT FRI JUL 11 2014

CURRENT ROUND OF CONVECTION CONTINUES TO MOVE EASTWARD...WITH THE
RAIN CURRENTLY MOSTLY ALONG AND EAST OF THE I 29 CORRIDOR. UPSTREAM
WEAK SHORT WAVE IS RESPONSIBLE FOR MUCH OF THIS ACTIVITY. SO FAR...
REDEVELOPMENT BEHIND THE MAIN COMPLEX IN OUR WESTERN ZONES HAS BEEN
LIMITED. THIS IS LIKELY DUE TO PERTURBED LOW LEVEL INFLOW FROM A
SECOND COMPLEX IN CENTRAL NEB. BUT FAIRLY STRONG 850MB THETAE
ADVECTION IS STILL WORKING THROUGH...AND REALLY DOES NOT EXIT OUR
FAR EASTERN ZONES UNTIL 15Z. SO AM EXPECTING SOME REDEVELOPMENT
ALMOST ANYWHERE EAST OF THE JAMES RIVER VALLEY INTO THE EARLY
MORNING HOURS. FURTHERMORE...LATEST 88D RADAR SCANS ARE SHOWING A
HOOKUP WITH OUR CURRENT CONVECTION...SOUTHWESTWARD INTO THE COLD
POOL OF THE NEB COMPLEX...WHICH WILL LIKELY FILL IN ACROSS OUR FAR
SOUTHERN ZONES INTO EARLY MORNING. THEREFORE ALL SAID...STILL HAVE
HIGH POPS IN OUR EASTERN AND SOUTHERN ZONES THROUGH 12Z...THEN
DECREASING THROUGH THE MORNING HOURS AS THE INFLUENCE OF THE SHORT
WAVE WANES. FROM LATE MORNING ONWARD...NOT EXPECTING A LOT OF
CONVECTION CHANCES IN OUR FORECAST AREA AS WE ARE FIRMLY PLANTED IN
BETWEEN TWO SHORT WAVES WITH RISING MID LEVEL HEIGHTS NOTED. NOT
REAL CONFIDENT ABOUT AFTERNOON SHOWERS OR STORMS IN OUR EASTERN
ZONES ALONG AN 850MB TROUGH AXIS...SO ONLY INCLUDED SLIGHT CHANCE
POPS FOR THOSE AREAS. IN OUR WESTERN ZONES...IT MAY BE TOO CAPPED
FOR ANYTHING TO DEVELOP SO HAVE THEM DRY. WITH SOME CLEARING
EXPECTED...AM EXPECTING TEMPERATURES TO BECOME QUITE WARM THIS
AFTERNOON. WENT WITH THE WARMEST GUIDANCE READINGS WHICH WERE THE
RAW VALUES AND CONSENSUS RAW READINGS...AND THEN EVEN IN MANY CASES
FURTHER WARMED TEMPERATURES ANOTHER DEGREE OR TWO.

TONIGHT...A FEW SEVERE STORMS ARE POSSIBLE IN OUR FAR SOUTHERN
ZONES...MAINLY FROM YANKTON...TO SIOUX CITY AND STORM LAKE. ANOTHER
SHORT WAVE MOVES EASTWARD...AND A SURFACE TO 850MB BOUNDARY SETS UP
DURING THE EVENING AND OVERNIGHT HOURS IN THOSE AREAS. CURRENTLY IT
LOOKS AS THOUGH WIND SHEAR IS A BIT LIMITED...WITH THE LOW LEVEL
FLOW RATHER WEAK. AND IF THE STORMS ARE ELEVATED...THE LOWEST 1KM OF
WIND SHEAR WILL LIKELY NOT BE TAPPED AT ANY RATE LEAVING A
MULTICELLULAR LOOKING HODOGRAPH. BUT THERE IS DECENT INSTABILITY...
WITH 925MB-850MB MU CAPES OF NEAR 2000 J/KG NUDGING NORTHWARD FROM
NEBRASKA...COUPLED WITH PLENTY OF LOW LEVEL MOISTURE TO TAP.
THEREFORE WOULD ALSO NOT RULE OUT SOME LOCALLY HEAVY RAIN IN SOME OF
OUR SOUTHERN ZONES. CURRENT THOUGHTS ARE THAT THE CONVECTION WHICH
FORMS DURING THE EVENING HOURS IN OUR SOUTHERN ZONES WILL OOZE
NORTHWARD ALONG THE LOW LEVEL BOUNDARY...GIVING A HIGH POP CHANCE
GENERALLY FROM I 90 AND POINTS SOUTHWARD.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 416 AM CDT FRI JUL 11 2014

A PRETTY STRONG UPPER LEVEL WAVE WILL CONTINUE TO MOVE ACROSS THE
AREA ON SATURDAY...INTERACTING WITH A FRONTAL BOUNDARY OVERHEAD.
THUS EXPECTING GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS
ACROSS THE AREA. EXPECTED EVOLUTION IS THAT CONVECTION THAT FORMS
OVER NORTHERN NEBRASKA ON FRIDAY NIGHT...WILL MOVE NORTH INTO OUR
CWA THROUGH SATURDAY MORNING...WITH SOME NEW DEVELOPMENT OVERHEAD AS
WELL. THIS ACTIVITY IS EXPECTED TO REMAIN ELEVATED...AND WITH
INSTABILITY PRETTY LIMITED...NOT SEEING MUCH OF A SEVERE RISK. STILL
SOME DIFFERENCES AMONG THE MODELS ON LOCATION OF THE GREATEST
COVERAGE OF STORMS...BUT CURRENT CONSENSUS SEEMS TO SUGGEST AREAS
FROM THE INTERSTATE 90 CORRIDOR AND POINTS SOUTH. THESE STORMS
SHOULD PUSH EAST THROUGH THE DAY...WITH THE NORTHWEST HALF OF THE
AREA LIKELY DRY BY EARLY TO MID AFTERNOON. AS THE DAY
PROGRESSES...STORMS MAY BECOME MORE SURFACE BASED AHEAD OF THE COLD
FRONT WITH AN INCREASING SEVERE THREAT. HOWEVER THIS APPEARS TO
HAPPEN SOUTHEAST OF THE CWA...POSSIBLY CLIPPING OUR FAR SOUTHEAST NEAR
STORM LAKE. THUS THE DAY 2 SPC OUTLOOK LOOKS GOOD. HIGHS ON SATURDAY
WILL BE IN THE UPPER 70S TO MID 80S...WARMEST IN THE WEST...WHERE WE
SHOULD SEE THE GREATEST AMOUNT OF CLEARING BY LATER IN THE DAY.

ONE MORE WARM DAY EXPECTED ON SUNDAY...AS OUR REGION REMAINS AHEAD
OF THE MAIN COLD FRONT. LOOKING AT HIGHS AGAIN IN THE UPPER 70S TO
MID 80S. COLD FRONT WILL PUSH ACROSS DURING THE AFTERNOON HOURS.
WILL NEED TO MONITOR CONVECTIVE CHANCES WITH THIS FRONTAL PASSAGE.
DESPITE THE LACK OF ANY SHORTWAVE...THE COMBINATION OF REMAINING LOW
LEVEL MOISTURE AND COOLING TEMPERATURES ALOFT...MAY BE ENOUGH TO GET
A FEW THUNDERSTORMS ALONG THE FRONT. DEEP LAYER SHEAR WILL BE AROUND
40 KTS...BUT INSTABILITY LOOKS PRETTY MEAGER AND THIN...POSSIBLY
APPROACHING 1000 J/KG. THUS AT THIS POINT SEVERE THREAT SEEMS
LOW...BUT GIVEN THE SHEAR CAN NOT RULE OUT A STRONGER
STORM...ESPECIALLY IF WE MANAGE SLIGHTLY HIGHER INSTABILITY THAN
CURRENTLY EXPECTED.

MUCH COOLER AIR WILL USHER INTO THE REGION SUNDAY NIGHT INTO TUESDAY
BEHIND THIS FRONT. LOWS SUNDAY NIGHT WILL BE IN THE 50S...AND BY
MONDAY NIGHT WE MAY SEE SOME AREAS DROP INTO THE UPPER 40S. FOR
HIGHS...LOOKING AT ONLY THE MID 60S TO MID 70S ON MONDAY AND
TUESDAY. THESE ARE AROUND 15 TO 20 DEGREES BELOW NORMAL FOR THIS
TIME OF YEAR...MORE TYPICAL OF LATE SEPTEMBER VALUES. RIDGING WILL
BEGIN TO BUILD BACK INTO THE AREA BY WEDNESDAY AND
THURSDAY...BRINGING A WARMING TREND. BY THURSDAY WE WILL SEE HIGHS
IN THE UPPER 70S TO MID 80S...ALTHOUGH THESE WILL STILL BE BELOW
AVERAGE. COULD SEE A FEW SHOWERS OR THUNDERSTORMS ON MONDAY EAST OF
INTERSTATE 29 AS THE TROUGH AXIS AND COLDEST AIR ALOFT SWING ACROSS
THE AREA. OTHERWISE NOT REALLY SEEING ANY PRECIPITATION CHANCES
TUESDAY THROUGH THURSDAY WITH HIGH PRESSURE IN CONTROL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 642 AM CDT FRI JUL 11 2014

IN THE NEAR TERM...THUNDERSTORMS WILL CONTINUE TO MOVE EASTWARD
ACROSS EXTREME NORTHEAST NEBRASKA...FAR SOUTHEAST SD...AND PARTS
OF NORTHWEST IA...AFFECTING THE KSUX TAF SITE. THEREFORE HAD TO
INCLUDE TSRA FOR KSUX WITH TEMPO MVFR CONDITIONS THROUGH THE EARLY
MORNING HOURS. BY MID TO LATE MORNING...THE CONVECTION SHOULD
EITHER BE WEAKENING OR EXITING OUR SOUTHERN ZONES. TO THE NORTH...
DENSE FOG IS NOTED IN SOUTHERN ND AND PORTIONS OF NORTHERN SD. DID
NOT INCLUDE STRATUS OR FOG IN THE KHON TAF SITE AT THIS TIME AS
THEIR LOW LEVEL WINDS ARE SOUTHERLY...COUPLED WITH DAYTIME HEATING
LIKELY ERODING THE FOG POTENTIAL AWAY. OTHERWISE ANOTHER SHORT
WAVE OF ENERGY WILL MOVE EASTWARD ACROSS THE AREA TONIGHT. CHANCES
FOR CONVECTION LOOK VERY GOOD FROM I 90 AND POINTS SOUTHWARD AFTER
EVENING. NORMALLY DO NOT LIKE TO INCLUDE THUNDERSTORM CHANCES THAT
FAR OUT IN THE TAF SITES...BUT PRECIPITATION LOOKS LIKELY AT THIS
TIME FOR KFSD AND KSUX. NORTH OF I 90...STORMS WILL LIKELY BE MORE
SCATTERED AS THE LOW LEVEL FOCUS REMAINS IN OUR SOUTHERN ZONES
AND DOES NOT LIFT NORTHWARD. THEREFORE LEFT TSRA OUT OF THE KHON
TAF SITE FOR NOW.

&&

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

$$

SHORT TERM...MJ
LONG TERM...CHENARD
AVIATION...MJ






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