000
FXUS63 KFSD 130347
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1047 PM CDT SUN MAY 12 2013

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 250 PM CDT SUN MAY 12 2013

CLEAR SKIES WILL BE REPLACED BY INCREASING HIGH AND SOME MID CLOUDS
BY THE MIDDLE OF THE NIGHT AS WARM FRONT DEVELOPS AND APPROACHES.
THERMALLY SUPPORTED LIFT WOULD BRING A SLIGHT EXCUSE FOR SPOTTY TAME
CONVECTION LATE TONIGHT INTO MONDAY NORTHERN EDGE OF FORECAST AREA
BUT WITH MOISTURE SLOW TO INCREASE WILL LEAVE OUT FOR NOW. THE SOUTH
SOUTHEASTERLY SURFACE BREEZE WILL CONTINUE TO REPLACE THE LIGHT AND
VARIABLE WINDS FROM WEST TO EAST TONIGHT. TEMPERATURES OF COURSE
WILL BE WARMER WITH NO FREEZE OR FROST. MONDAY WILL SEE THE WINDS
CONTINUE TO INCREASE AS THE WARM FRONT MOVES ACROSS AND IT WILL GET
BREEZY TO WINDY ESPECIALLY EAST AS THE FLOW BEGINS TO BECOME MORE
SOUTHWEST/WESTERLY TO THE WEST. TEMPERATURES WILL BE WARMER AS LONG
ADVERTISED  WITH PARTLY CLOUDY SKIES AND THE TOO LOW TO MENTION
THREAT DISCUSSED ABOVE OF SPOTTY SHOWERS/THUNDERSTORMS NORTH.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 250 PM CDT SUN MAY 12 2013

MONDAY NIGHT SHOULD BE A WARM ONE AS WINDS SETTLE TO THE WEST AND
SOUTHWEST AND WARM IN THE LOW LEVELS PREVENTS TEMPERATURES FROM
FALLING MUCH. THE 700MB TO 500MB LAPSE RATE INCREASE QUITE A BIT
OVERNIGHT BUT WITH A BIT OF A LACK OF MOISTURE ACCAS MAY EVEN BE
TOUGH TO COME BY. IT SEEMS THE BETTER CHANCE FOR ANY ACCAS OR
POSSIBLY ACCAS SPRINKLES WOULD BE IN THE NORTHERN CWA FROM ABOUT 9Z
TO 15Z TUESDAY. LOWS ON TUESDAY MORNING SHOULD RANGE FROM THE MID
50S IN THE EASTERN CWA TO 60 TO 65 IN THE WESTERN CWA.

TUESDAY STILL THE HOTTEST DAY OF THE WEEK AND WITH BREEZY TO WINDY
CONDITIONS A FIRE WEATHER MAY BECOME A THREAT. LATEST GUIDANCE SEEMS
TO BE HAVING TROUBLE WITH DEW POINTS...MAINLY TOO HIGH...WHICH HAS
BEEN A PROBLEM MUCH OF THE SPRING. BIG DIFFERENCES FROM THE RAW
MODEL OUTPUT WHICH PAINTS MID 50 TO LOWER 60S DEW POINTS DURING THE
AFTERNOON TO THE MOS OUTPUT WHICH IS CLOSE TO THE LOWER 50S THROUGH
THE DAY. BELIEVE THAT BOTH MAY END UP A LITTLE TOO HIGH WITH THE
POTENTIAL TO MIX TO CLOSE TO 700MB IN SPOTS DEW POINTS WILL TANK
INTO THE MID 40S TO AROUND 50 MOST OF THE AFTERNOON. EVEN THE SREF
OUTPUT WHICH HAS TOO MANY HIGH DEW POINT MEMBERS HAS A DECENT
PROBABILITY FOR RELATIVE HUMIDITY LESS THAN 30 PERCENT AS WELL AS
WINDS LIKELY AT OR ABOVE 20 MPH. MANY OF THE SREF SOUNDINGS SUPPORT
DEW POINTS BELOW 50 WHEN MIXED IN THE AFTERNOON. STILL JUST A SMALL
CHANCE FOR THUNDERSTORMS NEAR THE FRONT IN NORTHWEST IOWA BUT IT
LOOKS TO REMAIN CAPPED.

TUESDAY NIGHT WILL BE BREEZY IN THE EVENING THEN WINDS WILL SETTLE
DOWN TOWARDS SUNRISE...LEADING INTO A PLEASANT WEDNESDAY. LOWS
TUESDAY NIGHT SHOULD BE IN THE 50 TO 55 DEGREE RANGE WHILE HIGHS ON
WEDNESDAY WILL BE IN THE 70S.

FOR THE THURSDAY THROUGH SUNDAY TIME FRAME...THE POTENTIAL FOR
BUSIER WEATHER THROUGH THE WEEKEND...FRIDAY AND SATURDAY SEEM LIKE
THE BETTER CHANCES.

STRONG ZONAL FLOW IN PLACE THURSDAY WITH A WEAK RIDGE OF HIGH
PRESSURE GRADUALLY SHIFTING EAST. THIS SHOULD SUPPORT A PRETTY NICE
DAY WITH HIGHS LIKELY IN THE 70S AND WINDS ON THE LIGHT SIDE. THERE
WILL BE A FAIRLY WEAK WAVE PASSING TO THE NORTH AND NORTHEAST OF THE
AREA LATE WEDNESDAY NIGHT INTO THURSDAY AFTERNOON BUT THUNDERSTORM
CHANCES LOOK MINIMAL. THE LOW TO MID LEVEL CONVERGENCE WEAK AND
INSTABILITY ALSO WEAK. THERE ARE SOME ENHANCED LAPSE RATES ALOFT SO
MAYBE SOME ACCAS ON THE TAIL END OF THE WAVE BUT NOT ENOUGH TO ADD
ANY POPS FOR AT THIS TIME. FRIDAY MORNING SHOULD START OFF MILD THEN
EAST TO SOUTHEAST FLOW WILL DEVELOP THROUGH THE DAY. ANOTHER PRETTY
NICE DAY WITH HIGHS IN THE 70S TO LOWER 80S AND WINDS MAYBE IN THE
10 TO 20 MPH RANGE BY AFTERNOON.

FRIDAY NIGHT MAY POSE AN ELEVATED THREAT FOR HAILERS AND IF THE
SHEAR THAT IS BEING ADVERTISED FROM THE ECMWF AND GFS ARE CORRECT
SEVERE WEATHER WOULD BE PRETTY LIKELY. BOTH THE GFS AND ECMWF LEAVE
THE BOUNDARY LINGERING AROUND THE CWA ON SATURDAY AND WITH THE
TROUGH STILL TO THE WEST THIS MAKES SENSE. SHEAR ON SATURDAY NOT AS
GOOD BUT WITH THE POTENTIAL INSTABILITY WOULD STILL POSE AN
ADDITIONAL SEVERE WEATHER THREAT. IF THINGS TIME OUT AS EXPECTED ON
THE WEEKEND THE MAIN THREAT FOR THUNDERSTORMS ON SUNDAY WOULD BE
SOUTH OF THE AREA WITH COOLER AND DRIER AIR FILTERING IN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1035 PM CDT SUN MAY 12 2013

VFR CONDITIONS THROUGH THE TAF PERIOD. WINDS WILL BE LIGHT AND
VARIABLE OVERNIGHT THEN INCREASE FROM THE SOUTH LATE TONIGHT THROUGH
MONDAY. AFTER 15Z...WINDS WILL INCREASE AROUND 15 KT WITH GUSTS TO 25
KT AND TURN MORE WESTERLY IN THE AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 411 AM CDT SUN MAY 12 2013

SOUTHWEST WINDS WILL INCREASE ON MONDAY...ESPECIALLY ALONG AND EAST
OF INTERSTATE 29. AFTERNOON RELATIVE HUMIDITIES SHOULD REMAIN MAINLY
IN THE 30 TO 35 PERCENT RANGE BUT PARTS OF SOUTHWEST MINNESOTA COULD
DROP TO ABOUT 25 PERCENT SO VERY CLOSE TO RED FLAG CONDITIONS. ALSO
PARTS OF THE JAMES VALLEY WEST ON MONDAY COULD GET CLOSE BUT RIGHT
NOW BELIEVE THAT WINDS WILL SLACKEN A BIT IN THE AFTERNOON WITH THE
PASSING OF A TROUGH OF LOW PRESSURE SO WILL LEAN TOWARD VERY HIGH
FOR NOW. A MORE WIDESPREAD PROBLEM ON TUESDAY WITH BREEZY TO WINDY
CONDITIONS MOST LOCATIONS...HOTTER TEMPERATURES AND A HIGHER
PROBABILITY OF HUMIDITIES AT OR BELOW 25 PERCENT. WILL HAVE A FIRE
WEATHER WATCH FOR SOUTHWEST MINNESOTA ON TUESDAY.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
     EVENING FOR MNZ900.

IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...
FIRE WEATHER...08