Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 181059
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
559 AM CDT FRI JUL 18 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CDT FRI JUL 18 2014

FORECAST THEME IN THE SHORT TERM WILL BE GRADUALLY WARMING
TEMPERATURES...INCREASING WINDS...AND LIMITED RAIN CHANCES
OVERNIGHT.

EARLY THIS MORNING...SHORTWAVE INDUCED RETURN FLOW IS GRADUALLY
BRINGING LOW LEVEL MOISTURE BACK NORTHWEST INTO THE NORTHERN PLAINS.
WINDS WILL CONTINUE TO INCREASE THROUGH THE DAYTIME HOURS AS A
SURFACE TROUGH FORMS OVER THE WESTERN DAKOTAS AND SFC PRESSURE
GRADIENT TIGHTENS.  SOUTHWESTERLY WINDS 15 TO 25 KNOTS LIKELY FOR
MOST LOCATIONS BY MID-AFTERNOON.  DESPITE THE INCREASED SOUTHWEST
WINDS...TEMPERATURES WILL NOT CLIMB UPWARDS BY MUCH TODAY. FOR THE
MOST PART...STRONGEST LOW-LVL WARM ADVECTION IS FOCUSED WELL WEST OF
THE CWA.  ADDITIONALLY...MID-UPPER LEVEL WINDS WILL CONTINUE TO
SPREAD A VEIL OF SMOKE FROM FIRES IN THE PACIFIC NORTHWEST AND
WESTERN CANADIAN PROVINCES EASTWARD ACROSS THE REGION.

CONVECTION IS EXPECTED TO DEVELOP ALONG THE AFOREMENTIONED BOUNDARY
FROM THE BLACK HILLS THROUGH NORTH CENTRAL NORTH DAKOTA BY LATE
AFTERNOON. LIMITED MOISTURE AND RISING LOW-LEVEL TEMPS FURTHER EAST
SHOULD PREVENT ANY SUBSTANTIAL CONVECTION FROM PUSHING INTO THE AREA
AFTER MIDNIGHT...BUT WOULD NOT BE SURPRISED TO SEE A FEW LINGERING
SHOWERS/STORMS GRAZE THE NORTHERN ZONES INTO DAYBREAK OF SATURDAY.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 345 AM CDT FRI JUL 18 2014

WARMER AIR BEGINS TO MAKE A PUSH INTO THE FORECAST AREA ON SATURDAY
AND MAIN QUESTION IS HOW MUCH CLOUD COVER AND/OR HIGH LEVEL SMOKE
WILL LINGER THROUGH THE DAY...AND WHAT IMPACT THAT MAY HAVE ON LOW
LEVEL WARMING. MODELS SHOWING QUITE A BIT OF HIGH LEVEL RH ACROSS
THE REGION THROUGHOUT THE DAY...SO WILL KEEP TEMPS A BIT BELOW FULL
MIXING POTENTIAL DESPITE FAVORABLE SOUTHERLY FLOW. SHOULD STILL SEE
LOWER 80S EAST TO NEAR 90 ACROSS THE WEST. IN ADDITION TO LOW LEVEL
WARMING WILL SEE INCREASE IN LOW LEVEL MOISTURE...WITH DEW POINTS
CLIMBING INTO THE MID-UPPER 60S SOUTH OF WEAK BOUNDARY WHICH SAGS
INTO OUR FAR NORTH DURING THE DAY. VARIOUS SUBTLE SHORT WAVES MOVE
ACROSS THE REGION WHICH COULD INTERACT WITH THIS BOUNDARY...WITH
GREATEST TIMING CONSENSUS BRINGING POTENTIAL FOR SOME SPOTTY STORMS
ACROSS OUR WEST AND NORTH IN THE EVENING. FURTHER WARMING SURFACE
AND ALOFT EXPECTED FOR THE LATTER HALF OF THE WEEKEND...WITH MINIMAL
PRECIP THREAT BENEATH RISING HEIGHTS ALOFT. ANTICIPATE HIGHS SUNDAY
FROM 3 TO 8 DEGREES WARMER THAN SATURDAY...WITH WESTERN AREAS SEEING
FIRST POTENTIAL FOR HEAT INDICES NEARING TRIPLE DIGITS AS DEW POINTS
CONTINUE TO PUSH TOWARD 70 AND TEMPERATURES ALONG/WEST OF THE JAMES
RIVER CLIMB INTO THE MID-UPPER 90S.

LATTER PERIODS MONDAY THROUGH THURSDAY BEGINS WITH WARMEST DAY AS
MOST AREAS EXPECTED TO SEE HIGHS IN THE 90 TO 100 DEGREE RANGE. THIS
ALONG WITH DEW POINTS FROM THE UPPER 60S FAR WEST TO MID-UPPER 70S
IN THE CENTRAL AND EAST...WILL LEAD TO GREATEST POTENTIAL FOR TRIPLE
DIGIT HEAT INDICES FOR MUCH OF THE AREA. THINK MUCH OF THE DAYTIME
HOURS MONDAY SHOULD REMAIN DRY...BUT STRONGER WAVE TOPPING THE UPPER
RIDGE WILL BRING GREATEST CHANCE FOR THUNDERSTORMS TO NORTHERN AND
EASTERN PARTS OF THE FORECAST AREA MONDAY NIGHT INTO TUESDAY.

GFS/GEM APPEAR TO BE TRENDING TOWARD ECMWF FORECAST FROM THIS TIME
YESTERDAY...WITH STRONGER WAVE BRINGING A BREAK FROM THE RELATIVELY
SHORT HOT/HUMID STRETCH AS IT DRAGS COOLER AIR INTO THE AREA TUESDAY
NIGHT/WEDNESDAY. STILL SOME DISCREPANCIES IN TIMING AND STRENGTH OF
COOLING...BUT THIS WAVE SHOULD BRING HIGHS BACK INTO THE 80S-LOWER
90S FOR WEDNESDAY/THURSDAY...WITH LESS HUMID DEW POINTS IN THE 60S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 553 AM CDT FRI JUL 18 2014

VFR CONDITIONS EXPECTED THROUGH 12Z SATURDAY. AN INCREASING SURFACE
PRESSURE GRADIENT WILL RESULT IN BREEZY WINDS BY THIS AFTERNOON FROM
THE SOUTH. MODELS CONSISTENT IN DEVELOPING A SCT-BKN CU FIELD BY
THIS AFTERNOON...LOWER COVERAGE IN HURON. WIND SPEEDS WILL ONLY SLIGHTLY
LOWER THIS EVENING...AS CU FIELD DIMINISHES THERE WILL LIKELY BE SOME
MID-LEVEL INFLUENCE IN CLOUD COVER FROM THUNDERSTORMS WEST OF THE
CWA.


&&

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

$$

SHORT TERM...DUX
LONG TERM...JH
AVIATION...DUX






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