000
FXUS63 KFSD 120012
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
712 PM CDT SAT MAY 11 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 256 PM CDT SAT MAY 11 2013

CLEAR SKIES TONIGHT WILL BE ACCOMPANIED BY WINDS GOING LIGHT OVER
ALL OF THE FORECAST AREA. A NORTHWEST BREEZE MAY LINGER ALL NIGHT
FAR EAST BUT IT WILL BE DOWN TO THAT LIGHT CATEGORY LATE.
TEMPERATURES AND DEW POINTS HAVE BEEN GOING AS FORECAST ALL
DAY...AND THE COOLING TONIGHT SHOULD BE AS WE HAVE BEEN EXPECTING.
THEREFORE...THE FREEZE WARMING AND FROST ADVISORY WILL STAND AS IS
WITH NO HIGHLIGHT FOR THE FAR SOUTHWEST CORNER. SUNDAY WILL START
SUNNY WITH LIGHT TO CALM WINDS. WHILE A LITTLE SOUTHEAST BREEZE WILL
KICK UP WEST OF THE JAMES RIVER IN THE AFTERNOON...IT WILL NOT BE
TOO STRONG...AND THE WINDS WILL STAY LIGHT TO THE EAST. WARMER
TEMPERATURES WITH HIGHS 60 NORTHEAST TO 70 SOUTHWEST AS WE HAVE BEEN
CARRYING...THOUGH WITH THE LIGHT WINDS MOST OF THE DAY...AN
OVERFORECAST WOULD SURELY NOT BE COMPLAINED ABOUT. LOOKS LIKE THERE
WILL BE AN INCREASE IN HIGH CLOUDS...AT LEAST OVER SD...FROM THE
WEST STARTING LATE MORNING AND SOME OF THOSE CLOUDS COULD GET SEMI
THICK IN THE AFTERNOON.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 256 PM CDT SAT MAY 11 2013

HIGH PRESSURE WILL SHIFT EAST OF THE AREA SUNDAY EVENING ALLOWING A
SOUTHERLY FLOW TO DEVELOP OVERNIGHT. THIS WILL KEEP TEMPERATURES ON
THE MILD SIDE WITH LOWS FROM 45 TO 50 WEST OF INTERSTATE 29. A FEW
LOW SPOTS IN SOUTHWEST MINNESOTA AND NORTHWEST IOWA COULD CREEP DOWN
TO AROUND 40 WITH A SLACK PRESSURE GRADIENT THROUGH ABOUT MIDNIGHT
BUT NOT MUCH FARTHER AS SOUTHERLY FLOW WILL BECOME ESTABLISHED AFTER
MIDNIGHT.

HIGH TEMPERATURES MONDAY STILL PROVING TO BE TRICKY WITH A VERY
STRONG THERMAL GRADIENT IN PLACE. THE 850MB TEMPERATURES AT 18Z
MONDAY RANGES FROM ABOUT +12 NEAR MARSHALL MINNESOTA TO +19 AROUND
GREGORY. THE MODELS VARY A DECENT AMOUNT ON JUST HOW FAR EAST THIS
WARMER AIR WILL SHIFT FROM 18Z THROUGH 0Z TUESDAY WHICH MAKES A HUGE
DIFFERENCE ON HIGH TEMPERATURES. THE GFS IS QUITE A BIT COOLER THAN
THE ECMWF AND NAM AND SOME OF THE DIFFERENCE APPEARS TO BE THAT THE
ECMWF AND NAM BUILD AND BROADEN THE UPPER LEVEL RIDGE THROUGH THE
DAY WHILE THE GFS STILL SEES EFFECTS FROM THE EXITING JET STREAK
WHICH DOES NOT ALLOW THE RIDGE TO BUILD EAST AS QUICKLY. THE GEM
UNFORTUNATELY IS A BIT OF A WASH BETWEEN THESE TWO SOLUTIONS BUT
WILL STILL AIM TOWARDS THE WARMER SOLUTIONS...PROBABLY A BLEND OF
THE GOING FORECAST WITH THE LATEST GEM/ECMWF/NAM. WHILE A BOUNDARY
WILL WORK IN DURING THE DAY AT THIS TIME THE POTENTIAL FOR
THUNDERSTORMS JUST DOES NOT APPEAR TO BE THERE. SOME SURFACE BASED
CAPE AROUND 500 TO 1000 J/KG BUT FAIRLY WELL CAPPED SOME WILL NOT
INCLUDE ANY POPS AT THIS TIME. ELEVATED CAPE PRETTY NON EXISTENT.

A LIGHT WEST TO SOUTHWEST COMPONENT TO THE WIND WILL REMAIN IN PLACE
MONDAY NIGHT AND WITH A WARM LOW LEVEL THERMAL FIELD SUSPECT THAT
LOWS WILL BE PRETTY WARM. AIMING FOR MID 50S TO AROUND 60.

TUESDAY LOOKING LIKE THE WARMEST DAY OF THE WEEK...ESPECIALLY FOR
AREA SOUTH OF INTERSTATE 90. THE BOUNDARY IS COMING DOWN JUST A BIT
MORE QUICKLY THAN PREVIOUSLY FORECAST AND IS AGREED UPON BY ALL
MODELS...ALTHOUGH THE NAM IS THE SPEEDIEST AND WOULD MAKE THE
BIGGEST DIFFERENCE...TAKING THE FRONT TO OMAHA BY 0Z WEDNESDAY WHILE
THE OTHER MODELS ARE CLOSER TO SIOUX CITY TO SPENCER 0Z WEDNESDAY.
WILL AIM FOR MID 80S IN THE FAR NORTH CWA TO MID 90S OVER THE
SOUTHERN FOURTH OF THE CWA. ONCE AGAIN MOISTURE VERY SPARSE IN THIS
SET UP WITH LITTLE IF ANY ELEVATED INSTABILITY...SO LOOKING AT
MAINLY A SURFACE BASED THREAT...AND THIS THREAT IS NOT TOO GOOD. SO
NOT REALLY EXPECTING ANY SEVERE WEATHER AND POSSIBLY NO
THUNDERSTORMS AT ALL. THERE IS SOME LAGGING UPPER LEVEL SUPPORT AND
A MID LEVEL BOUNDARY TUESDAY EVENING AFTER THE SURFACE FRONT SO WILL
MAINTAIN SOME LOW POPS FOR THIS MINOR THREAT.

NEARLY ZONAL FLOW THROUGH THE PERIOD WITH A FEW WAVES MOVING THROUGH
THE FLOW...ESPECIALLY TOWARDS THE WEEKEND. WEDNESDAY AND THURSDAY
LOOK TO BE WARM WITH NOT TOO MUCH WIND AS HIGH PRESSURE MOVES ACROSS
THE AREA. WEDNESDAY WINDS COULD BE PRETTY LIGHT AND WITH 925MB
TEMPERATURES FROM ABOUT 15 TO 20 DEGREES SURFACE TEMPERATURES IN THE
70S LOOK PRETTY LIKELY. SHOULD BE A NICE DAY. BY THURSDAY HIGH
PRESSURE WILL BECOME MORE DIFFUSE AND SHIFT TO THE SOUTH AND EAST OF
THE CWA...BRINGING A BIT OF A SOUTHERLY WIND. NOT REALLY LOOKING AT
ANY MOISTURE RETURNING THURSDAY BUT SLIGHTLY ENHANCED MIXING AND
LOWER LEVEL TEMPERATURES A BIT WARMER SHOULD SUPPORT HIGHS A FEW
DEGREES WARMER...MAYBE MORE WIDESPREAD MID 70S TO AROUND 80. BY
FRIDAY THE SET UP BECOMES POTENTIALLY MORE INTERESTING AS
TROUGHINESS BUILDS OVER THE NORTHERN ROCKIES AND DEEPER SOUTHERLY
FLOW SETS UP OVER THE CENTRAL AND SOUTHERN PLAINS. THIS MAY ALLOW
FOR BETTER MOISTURE TO TRANSPORT NORTHWARD AND WITH THE POTENTIAL
FOR A BOUNDARY AROUND ON FRIDAY AND AGAIN SATURDAY THE THREAT FOR
THUNDERSTORMS...A FEW SEVERE...WILL EXIST. THE BETTER CHANCE WILL
LIKELY BE ON SATURDAY WHICH WILL ALLOW FOR DEEPER MOISTURE TO SHIFT
NORTH BUT CHANCES WILL BE NEEDED BOTH DAYS...ESPECIALLY SOUTH OF
INTERSTATE 90.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 658 PM CDT SAT MAY 11 2013

STRONG NORTHWESTERLY WINDS GUSTING TO AROUND 25 KTS AT TIMES WILL
DIMINISH AFTER SUNSET AND BECOME LIGHT AND VARIABLE AFTER 06Z.
RELATIVELY LIGHT WINDS WILL CONTINUE THROUGH THE DAY SUNDAY.
OTHERWISE...VFR CONDITIONS THROUGH THE TAF PERIOD.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR SDZ052-058-059-
     064-065-068>071.

     FREEZE WARNING FROM 3 AM TO 9 AM CDT SUNDAY FOR SDZ038>040-
     053>056-060>062-066-067.

MN...FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR MNZ081-090.

     FREEZE WARNING FROM 3 AM TO 9 AM CDT SUNDAY FOR MNZ071-072-080-
     089-097-098.

IA...FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR IAZ003-013-014-
     020>022-031-032.

     FREEZE WARNING FROM 3 AM TO 9 AM CDT SUNDAY FOR IAZ001-002-012.

NE...FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR NEZ013-014.

&&

$$

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