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000
FXUS63 KFSD 132357
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
657 PM CDT MON MAY 13 2013

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 255 PM CDT MON MAY 13 2013

WARM FRONT CROSSING CONTINUES TO TURN WINDS TO SOUTHWESTERLY AND
THEY SHOULD EVEN GO NORTHWESTERLY FOR A SPELL IN OUR NORTHWEST...BUT
DURING THE NIGHT UNDER TEMPORARILY RELAXED GRADIENT THEY SHOULD
REVERT TO S TO SW. OTHERWISE THE HIGH CLOUDS WHICH ARE MARGINALLY
DENSE WILL DECREASE THROUGH THE EVENING AND SKIES SHOULD GO MOSTLY
CLEAR. LOW TEMPERATURES SHOULD BE IN LINE WITH WHAT WE HAVE BEEN
CARRYING. THE RELAXED GRADIENT AND CLEARING SKIES SHOULD ALLOW
COOLING TO THE MID 50S TO LOWER 60S...MILD OF COURSE BUT WITH MORE
WIND THEY COULD HANG QUITE A BIT WARMER IN THIS WARMING AIR. TUESDAY
SHOULD NO SEE TOO MUCH OF AN INCREASE IN CLOUDS MOST OF THE DAY
THOUGH SOME HIGH AND MID CLOUDS LIKELY ESPECIALLY NORTH. DESPITE
SOME MOISTURE INCREASE AS THE COLD FRONT ARRIVES...THE AIR WILL BE
TOO DRY FOR EXTENSIVE CLOUD COVER OR CONVECTION. THE SOUTHWEST WINDS
WILL PICK UP PRETTY WELL AHEAD OF THE FRONT...AND THE NORTHWEST
WINDS WHICH ARRIVE BEHIND THE FRONT WILL ALSO BE FAIRLY STRONG. DO
NOT FORESEE A WIND ADVISORY AT THIS POINT BUT FIRE WEATHER WILL BE
AFFECTED...SEE THAT SECTION. TEMPERATURES WILL BE CLOSE TO WHAT WE
HAVE BEEN GOING FOR WITH THE REAL HOT WEATHER SOUTHEAST...THOUGH
FEEL WE HAVE BEEN KEEPING THE AREA BEHIND THE FRONT A TAD TOO COOL
CONSIDERING THE MIXING FACTOR. STILL ADDS UP TO MID 80S NORTHWEST TO
MID 90S SOUTHEAST.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 255 PM CDT MON MAY 13 2013

TUESDAY NIGHT INTO WEDNESDAY WILL SEE COOLER AIR SETTLE SOUTH. A
NORTH WINDS WILL GRADUALLY DIMINISH WITH LITTLE IN THE WAY OF WIND
EXPECTED BY WEDNESDAY AFTERNOON. THIS SHOULD SET UP A VERY
PLEASANT DAY WITH LOWS STARTING OUT FROM THE UPPER 40S TO MID 50S
THEN HIGHS MAINLY IN THE 70S.

WEDNESDAY NIGHT WILL SEE HIGH PRESSURE SHIFT EAST BUT LIGHT WINDS
IN MANY LOCATIONS THROUGH THE NIGHT. THUS LOWERED LOWS A LITTLE
AND THEY ARE MAINLY FROM ABOUT 48 TO 52 IN THE EAST AND 50 TO 55
WEST.

THURSDAY SHOULD BE A FAIRY NICE DAY AS ZONAL FLOW REMAINS IN PLACE
AND SOUTHERLY FLOW GRADUALLY DEVELOPS FROM WEST TO EAST. FOR THE
MOST PART THE LOW LEVEL THERMAL FIELD SUPPORTS HIGH TEMPERATURES
MAINLY IN THE 70S. BY THURSDAY NIGHT AS WEAK WAVE WILL MOVE THROUGH
THE FLOW WHICH WILL ENHANCE THE LOW LEVEL JET. SOUNDINGS INDICATE
THE BEST LEVEL FOR PARCEL ASCENT WILL BE ABOUT 800MB WITH CAPE
VALUES LIKELY IN THE 500 TO 1000 J/KG RANGE. EFFECTIVE SHEAR NOT
OVERLY IMPRESSIVE BUT IF THIS SET UP DOES COME TOGETHER MAY SEE A
FEW ELEVATED HAILERS.

A SERIES OF WAVES WILL THEN MOVE THROUGH THE UPPER LEVEL FLOW
FRIDAY THROUGH SUNDAY. THE MAIN WAVE LOOKS TO EJECT ONTO THE PLAINS
SATURDAY NIGHT WITH WHAT SHOULD BE THE BETTER CHANCE FOR RAIN AND
THUNDERSTORMS ACROSS THE AREA. MAINLY LOOKING AT DEEPER MOISTURE
SATURDAY WHICH WILL AID IN DEVELOPMENT. MOST OF THE MODELS ARE
SPORADICALLY PRODUCING CONVECTION DURING THIS TIME FRAME AND TOUGH
TO NAIL DOWN JUST WHEN AND WHAT IS GOING TO OCCUR WITH THE MESSY
FLOW. REGARDLESS WILL HAVE SOME FAIRLY HIGH POPS IN THE FORECAST
FRIDAY NIGHT INTO SUNDAY AND DEFINITELY SEE A THREAT FOR SOME
SEVERE WEATHER AS WELL. COOLER AIR WILL SETTLE INTO THE AREA
SUNDAY INTO MONDAY WITH TEMPERATURES LIKELY BACK TO AROUND NORMAL
AS WELL AS POTENTIALLY BREEZIER CONDITIONS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 654 PM CDT MON MAY 13 2013

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. SURFACE INVERSION
SETTING UP THIS EVENING AND GUSTY CONDITIONS SHOULD RAIDLY
SUBSIDE. GUSTY CONDITIONS WILL RETURN 14-15 Z WITH WINDS SHIFTING
TO THE NORTHWEST THROUGHOUT THE DAY AS A COLD FRONT MOVES THROUGH.

&&

.FIRE WEATHER...
ISSUED AT 138 PM CDT MON MAY 13 2013

RED FLAG WARNING HAS BEEN ISSUED FOR SOUTHWEST MN PART OF AND
NORTHWEST IA FOR THIS AFTERNOON AND CONTINUES UNTIL 6 PM CDT. THE
STRONG WINDS AND LOW RELATIVE HUMIDITIES WILL BE A PROBLEM AGAIN
TUESDAY...ONLY OVER ALL OF THE AREA. THE HIGHER DEW POINTS TUESDAY
WILL BE MORE THAN COMPENSATED FOR BY THE VERY WARM TO HOT
TEMPERATURES. THERE COULD BE SOMEWHAT OF A SLIGHT LULL NEAR THE
FRONT IN THE SHIFTING ZONE BUT FEEL THE WINDS WILL BE HIGH ENOUGH
CONTINUOUSLY ENOUGH TO UPGRADE THE FIRE WEATHER WATCH TO A RED FLAG
WARNING. THIS WILL BE FOR THE SAME TIME PERIOD THE WATCH WAS FOR. WE
HAVE ALREADY HAD FIRE ACTIVITY IN SOUTHWEST MN THIS AFTERNOON AND
THE SAME COULD HAPPEN ANYWHERE TUESDAY. RECENT GREENING OF GRASSES
HAS BEEN AT LOW LEVELS AND FIRES MAY NOT BE REAL QUICK TO
START...BUT MAY SPREAD VERY QUICKLY IN THE LINGERING DORMANT TALL
GRASSES.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING FROM NOON TO 8 PM CDT TUESDAY FOR SDZ255>258.

MN...RED FLAG WARNING FROM NOON TO 8 PM CDT TUESDAY FOR MNZ900.

IA...RED FLAG WARNING FROM NOON TO 8 PM CDT TUESDAY FOR IAZ300-301.

NE...RED FLAG WARNING FROM NOON TO 8 PM CDT TUESDAY FOR NEZ249.

&&

$$

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