Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 101954
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
ISSUED BY NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
254 PM CDT THU JUL 10 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 254 PM CDT THU JUL 10 2014

THIS AFTERNOON...SATELLITE AND RADAR INDICATE A DISTURBANCE
TRACKING EAST ACROSS SOUTHERN NODAK AND NORTHERN SODAK. A FEW
SHOWERS ARE ACCOMPANYING IT NORTH OF I-90 WITH DRY AND PARTLY
SUNNY CONDITIONS ELSEWHERE. THIS DISTURBANCE WILL BE THE MAIN
PLAYER TONIGHT FROM EAST CENTRAL SODAK INTO CENTRAL/SOUTHERN MN.
FURTHER TO THE WEST IN THE SLIGHT RISK AREA OF SOUTHERN
SODAK...NOT TOO MUCH IS ONGOING THIS AFTERNOON AND THERE IS EVEN A
LACK OF CU BUILDING.

AS THE DISTURBANCE CONTINUES EASTWARD THIS EVENING...SHOWERS AND
THUNDERSTORMS WILL GROW MORE NUMEROUS AS THE LLJ STRENGTHENS AND
MOISTURE TRANSPORT INCREASES. A BAND OF FRONTOGENESIS /EVIDENT IN
A BAND OF CLOUDS EXTENDING FROM THE DISTURBANCE TO THE WY/MT
BORDER/ WILL FOCUS THIS ACTIVITY FROM EAST CENTRAL SODAK INTO
WEST CENTRAL MN LATE THIS EVENING. WITH THE LLJ ONLY SLOWLY VEERING
TONIGHT...THESE THUNDERSTORMS WOULD LIKELY BECOME ANCHORED AND
PRODUCE A HEAVY RAIN THREAT. SEVERAL MESO MODELS INCLUDING THE
HRRR AND HOPWRF HAVE BEEN ADVERTISING SEVERAL INCHES WITHIN A
BAND JUST NORTH AND EAST OF THE FSD CWA...BUT A FEW RUNS HAVE
WANDERED NORTH AND SOUTH A BIT. SO...THERE IS STILL A BIT OF
UNCERTAINTY AS TO WHERE THIS WILL FORM BUT IT WILL BE CLOSE TO THE
BORDER WITH WFOS ABR/MPX. INCREASED POPS INTO THE CATEGORICAL RANGE
FOR LINCOLN...LYON...COTTONWOOD...AND MURRAY COUNTIES WITH
LIKELIES EXTENDING AS FAR WEST AS HURON AND AS FAR SOUTH AS
SPENCER IA.

20Z ANALYSIS IS ALREADY SHOWING +14C AT 700MB HEADING NORTHEAST
INTO SWRN SD AND 850 MB MOISTURE TRANSPORT SETTING UP OVER ERN SD.
IN ADDITION...HEIGHTS ARE BUILDING ACROSS THE CENTRAL PLAINS SO
NOT SEEING MUCH SUPPORT FOR CONVECTIVE ACTIVITY SOUTH OF I-90 AND
WEST OF I-29 TONIGHT. THERE MAY BE A FEW ROGUE CELLS THAT
DEVELOP...BUT THE MOST WIDESPREAD ACTIVITY SHOULD REMAIN NORTH AND
EAST. THUS...REDUCED POPS ACROSS THE SOUTH HALF TO CHC OR SCHC.

THE FRONT WILL SAG SOUTH AND CONFINE THE BEST POPS TO IOWA AND
NEBRASKA FRIDAY. KEPT POPS IN THE CHC CATEGORY WITH THE ATMOSPHERE
LOOKING LARGELY CAPPED DUE LARGER HEIGHTS EXPANDING EASTWARD.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 254 PM CDT THU JUL 10 2014

AS WE PROGRESS THROUGH THE SATURDAY-THURSDAY PERIOD WE/LL SEE QUITE
THE EVOLUTION OF LARGE SCALE FEATURES AND WEATHER ACROSS THE AREA.
THINGS WILL START OUT WARM WITH THE UPPER JET NORTH OF THE AREA...
BUT AN UNSEASONABLY DEEP UPPER LOW WILL DROP SOUTH/EAST FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND GREAT LAKES REGION DURING THE
SUNDAY NIGHT THROUGH TUESDAY PERIOD. THIS WILL BRING VERY COOL
TEMPERATURES TO MUCH OF THE REGION... WITH THE HEART OF THE COLD AIR
TRACKING ACROSS MINNESOTA AND POINTS EAST. SOME PCPN CHANCES WILL
LOITER ACROSS THE REGION SATURDAY INTO SUNDAY PRIOR TO THE ARRIVAL
OF THE COLD FRONT AND UPPER TROUGH... WITH DIURNAL CHANCES FOR PCPN
AFTER THAT AS THE UPPER COLD POOL SWINGS ACROSS THE REGION. BEST
CHANCES FOR PCPN PRIOR TO FROPA WILL BE ACROSS THE SOUTHERN PORTIONS
OF THE AREA WHERE THE BAROCLINIC ZONE AND BEST INSTABILITY ARE
PROGGED... WITH CHANCES FOR DIURNAL SHRA FOLLOWING FROPA LOCATED
OVER EASTERN AREAS WHERE BOUNDARY LAYER CYCLONIC FLOW WILL BE MOST
PREVALENT AND LOW-MID LEVEL LAPSE RATES WILL BE STEEPEST BENEATH THE
MID-UPPER LEVEL COLD POOL. WE WILL SEE RIDGING BEGIN TO WORK INTO
THE AREA AFTER TUESDAY... WITH DRY WEATHER AND MODERATING
TEMPERATURES FOR THE LAST FEW DAYS OF THE FORECAST PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 103 PM CDT THU JUL 10 2014

TWO MAIN CONCERNS THIS TAF PERIOD DEAL WITH THUNDER CHANCES THIS
AFTERNOON AND OVERNIGHT...FOLLOWED BY MVFR OR LOWER CIG POTENTIAL
LATE TONIGHT INTO FRIDAY MORNING. SHORT TERM HI-RES MODELS HAVE
REALLY BACKED OFF ON THUNDER POTENTIAL AT THE FSD TAFS...KEEPING
MOST OF THE ACTIVITY ACROSS NE SODAK INTO WC MN THIS AFTERNOON AND
OVERNIGHT. KEPT TAF SITES DRY...THOUGH WILL HAVE TO MONITOR
HON/FSD AS ACTIVITY MAY NOT BE TOO FAR NORTH OF THESE LOCALS. FOR
CIGS...CONTINUED MOIST SRLY FLOW OVERNIGHT WILL ALLOW DEWPS TO
RISE TO NEAR 70. NAM BUFKIT SOUNDINGS DO NOT REALLY SUPPORT THE
DEVELOPMENT OF MVFR CIGS OVERNIGHT...SO SHIED AWAY FROM LAMP
GUIDANCE. FEEL BEST CHANCE FOR MVFR CIGS WILL COME AFTER SUNRISE
ONCE MIXING GETS GOING...THE INITIAL CU FIELD WOULD COME IN
MVFR...SIMILAR TO WHAT WE ARE SEEING THIS MORNING OUT IN CENTRAL
NEB. FOR NOW...HAVE THIS HAPPENING AT SUX...BUT A SIMILAR SCENARIO
COULD OCCUR AT FSD AS WELL. ALSO LOOKED INTO THE POTENTIAL FOR
WIND SHEAR TONIGHT...BUT 0-1KM SHEAR IS MARGINAL AT 30 KTS AND
WITH WIND DIRECTION ONLY CHANGING FROM ABOUT 170 AT THE SFC TO 200
DEGS AT 2K FT...DECIDED TO KEEP IT OUT OF TAFS.


&&

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

$$

SHORT TERM...BORGHOFF
LONG TERM...TRH
AVIATION...MPG






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