Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KFSD 281125
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
625 AM CDT SUN SEP 28 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT SUN SEP 28 2014

BOUNDARY ACROSS CENTRAL SOUTH DAKOTA IS EXPECTED TO PIVOT AND BECOME
MORE WEST TO EAST ORIENTED THROUGHOUT THE DAY AS LATITUDINAL UPPER
LEVEL TROUGH MOVES ACROSS THE ROCKIES.  THE REORIENTED BOUNDARY IS
EXPECTED TO BECOME THE WARM FRONT FOR THE LOW PRESSURE SYSTEM TO THE
WEST. TEMPERATURES WILL STILL BE QUITE MILD TODAY...AND HAVE KEPT
HIGHS AT OR ABOVE GUIDANCE.  WITH THE WARM FRONT STALLING ACROSS THE
NORTHERN HALF OF THE FORECAST AREA TODAY...SHOULD SEE INCREASING
CLOUDS THROUGHOUT THE DAY....THOUGH ATMOSPHERE DOESN/T BECOME
UNSTABLE TILL THE 925 HPA BOUNDARY SAGS SOUTH TOWARDS THE HIGHWAY 14
CORRIDOR AROUND 00Z.  INTRODUCED POPS ACROSS CENTRAL SOUTH DAKOTA
INTO THE HIGHWAY 14 CORRIDOR WHERE THE FRONTOGENETIC FORCING IS
QUITE STRONG. ATMOSPHERE IS WEAKLY UNSTABLE ABOVE THE ELEVATED
BOUNDARY...SO COULD SEE A FEW LIGHTNING STRIKES WITH ANY ACTIVITY
THAT DEVELOPS. WITH FAIR AMOUNT OF CLOUDS AND SOUTHERLY WINDS
DRAWING INCREASING MOISTURE INTO THE REGION...SHOULD BE A MILD
NIGHT ONCE AGAIN WITH LOWS IN THE UPPER 50S TO NEAR 60.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 408 AM CDT SUN SEP 28 2014

FAIRLY GOOD MODEL CONSENSUS IN PUSHING LOW LEVEL BOUNDARY  TO
SOMEWHERE BETWEEN I-90 AND MISSOURI VALLEY MONDAY...BEFORE
LIFTING BACK TO THE NORTHEAST AHEAD OF THE PRIMARY UPPER TROUGH
MONDAY NIGHT AND TUESDAY. THIS WILL LEAD TO A COOLER DAY THEN
PREVIOUSLY EXPECTED FOR MUCH OF THE AREA MONDAY...ALONG WITH MORE
CLOUDS AND A FEW LIGHT SHOWERS NEAR/NORTHEAST OF THE BOUNDARY.
HAVE COOLED HIGHS INTO THE MID 60S FOR THE KBKX-KMML STRETCH ON
MONDAY...WITH READINGS STILL PUSHING NEAR 80 IN SOUTHERN PARTS OF
THE FORECAST AREA. COULD BE A SHARPER GRADIENT IN TEMPS SOMEWHERE
BETWEEN THESE TWO AREAS...BUT WITH UNCERTAINTY IN BOUNDARY
LOCATION...WILL KEEP GRADIENT ON THE BROADER SIDE FOR NOW.

ALSO SEEING GOOD CONSENSUS ON TIMING/TRACK OF NEGATIVE TILT UPPER
TROUGH SWINGING THROUGH THE NORTHERN PLAINS TUESDAY/TUESDAY NIGHT.
DECENT SPEED SHEAR EAST OF THE WAVE AS MID-UPPER LEVEL JET SLIDES
THROUGH THE AREA...BUT ONLY MODEST INSTABILITY PROGGED AT THIS
TIME...SO SEVERE THREAT APPEARS LIMITED. CANNOT ARGUE WITH SPC
OUTLOOK THAT SEVERE POTENTIAL COULD RAMP UP IF WE CAN ATTAIN GREATER
INSTABILITY...AND THUS WILL ADD MENTION OF ISOLATED SEVERE INTO HWO.
POTENTIAL FOR BETTER INSTABILITY SHOWN IN SOME MODELS ACROSS OUR
SOUTHEAST BY WEDNESDAY AFTERNOON AS MID LEVEL LAPSE RATES STEEPEN IN
THE WAKE OF TROUGH LIFTING NORTH. SHEAR GENERALLY WEAKER...BUT GFS
AND CANADIAN DO SHOW 70+KT UPPER LEVEL JET MOVING INTO OUR
SOUTHEAST DURING THE DAY...WHICH COULD SUPPORT SOME STRONGER
STORMS ALONG THE BOUNDARY.

SHOULD GENERALLY SEE A DRYING TREND THROUGH THE END OF THE WEEK...
WITH FRIDAY THE COLDEST DAY WHEN HIGHS COULD STRUGGLE TO REACH 60 IN
SOME AREAS. IF COLDER MODELS VERIFY...MAY HAVE TO WATCH FOR POSSIBLE
FROST FRIDAY NIGHT...THOUGH AT THIS TIME EVEN THE COLDER MODELS KEEP
WINDS HIGH ENOUGH OVERNIGHT TO LIMIT THREAT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 620 AM CDT SUN SEP 28 2014
SCATTERED TO BROKEN ELEVATED THUNDERSTORMS ACROSS FAR SOUTHEASTERN
SOUTH DAKOTA DRIFTING VERY SLOWLY TO THE NORTHEAST. EXPECT STORMS
TO FALL APART AN HOUR OR TWO AFTER SUNRISE. THESE STORMS ARE NOT
EXPECTED TO AFFECT THE 5 MILE RINGS AROUND TAF SITES...SO DID NOT
MENTION IN FORECAST. FRONT ACROSS CENTRAL SOUTH DAKOTA IS
EXPECTED TO SAG SOUTH THROUGH THE DAY TODAY. EXPECT ELEVATED FRONT
TO BECOME FOCUS MECHANISM FOR SHOWERS/ISOLATE THUNDER...AND ADDED
MENTION IN KHON TAF. WITH ELEVATED NATURE INITIALLY DID NOT ADD
MENTION OF VISIBILITY RESTRICTION BUT COULD BE SOME LOWER MVFR
CEILINGS DEVELOPING POST FRONTAL PASSAGE. &&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.