Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 212059
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
359 PM CDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 359 PM CDT THU MAY 21 2015

A SURFACE RIDGE AXIS WILL SLIDE ACROSS THE REGION TONIGHT... AND
WINDS WILL DIE OFF QUICKLY IN THE EVENING WITH DECOUPLING AND A
RELAXING GRADIENT. IT WILL BE MOSTLY CLEAR OVERNIGHT...AND IN
COMBINATION WITH THE LIGHT WINDS WILL ALLOW FOR OPTIMAL COOLING. IN
LIGHT OF THAT...STAYED ON THE LOW SIDE OF GUIDANCE WITH MINS IN THE
LOWER TO MID 40S.

THE HIGH WILL PUSH OFF TO THE EAST ON FRIDAY. WINDS WILL BECOME
SOUTHERLY ON THE BACKSIDE OF THE HIGH...AND PICK UP IN OUR WEST
DURING THE AFTERNOON AS THE GRADIENT TIGHTENS UP A BIT. AN UPPER
LEVEL SHORTWAVE WILL LIFT THROUGH WESTERN NEBRASKA DURING THE
DAY...AND WILL SEE AN INCREASE IN CLOUDS FROM THE SOUTHWEST DURING
THE AFTERNOON. IN ADDITION...WITH MIDLEVEL WARM AIR
ADVECTION/ISENTROPIC LIFT NUDGING INTO OUR SOUTHWEST OUT AHEAD OF
THE SYSTEM...CANNOT RULE OUT A SHOWER IN OUR SOUTH CENTRAL SOUTH
DAKOTA ZONES IN THE LATE AFTERNOON. WITH MOSTLY SUNNY SKIES FOR A
GOOD BIT OF THE DAY...WILL SEE HIGHS TOP OUT IN THE LOWER TO MID 70S
IN MOST PLACES...THOUGH REMAINING IN THE 60S THROUGH THE
SOUTHWESTERN CWA WHERE CLOUDS WILL INCREASE MORE QUICKLY.


.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 359 PM CDT THU MAY 21 2015

ACTIVE WEATHER PATTERN EXPECTED THROUGH THE MID AND LONG RANGE WHICH
WILL BRING DAILY CHANCES FOR SHOWERS AND STORMS TO THE REGION.
MOISTURE WILL BEGIN SLOWLY STREAMING NORTHWARD FRIDAY NIGHT...WITH
DEWPOINTS RETURNING TO 50S ON SATURDAY. CLOUDS AND SCATTERED LIGHT
RAIN SHOWERS BUILD SOUTHWEST TO NORTHEAST OVERNIGHT...BUT COOL
TEMPERATURES ALOFT WILL SUBDUE THUNDERSTORM ACTIVITY.  OVERCAST
SKIES WILL PERSIST INTO SATURDAY ALONG WITH SCATTERED SHOWERS AND
ISOLATED STORMS. IT DOES NOT LOOK LIKE A WASH OUT BY ANY MEANS...BUT
A MID LEVEL IMPULSE LIFTING INTO THE CENTRAL HIGH PLAINS WILL KEEP
RAIN CHANCES IN THE PICTURE ALL DAY. THERE ARE STILL SOME MODEL
DIFFERENCES IN THE TIMING AND NORTHWARD EXTENT OF THIS WAVE...SO IT
IS HARD TO PINPOINT WHEN AND WHERE A BREAK IN THE ACTIVITY MAY BE.
WITH COOL TEMPERATURES ALOFT AND CLOUDY SKIES...TEMPERATURES WILL BE
SEASONALLY COOL IN THE 60S.

SATURDAY NIGHT AND SUNDAY...THE MAIN UPPER LOW BEGINS EMERGING IN
THE HIGH PLAINS...WITH SURFACE LOW PRESSURE LIKELY STRENGTHENING
NEAR THE KANSAS...NEBRASKA AND COLORADO BORDER. SHOWERS AND
THUNDERSTORMS LOOK LIKELY DURING THIS PERIOD...ALTHOUGH AGAIN EXACT
TIMING AND LOCATION OF THIS ACTIVITY IS STILL UNCERTAIN. EFFECTIVE
SHEAR AND CAPE LOOK PRETTY WEAK...SO SEVERE WEATHER DOES NOT LOOK
VERY FAVORABLE AT THIS POINT.

HEADING INTO MONDAY AND TUESDAY...THE UPPER LOW GRADUALLY LIFTS
NORTHEAST INTO THE NORTHERN PLAINS AND WOBBLES INTO THE WESTERN
GREAT LAKES. THE GFS AND ECMWF MOVE THE WAVE OUT FASTER THAN THE
GEM...WHICH HOLDS ONTO THE WAVE AS LATE AS TUESDAY EVENING.
SCATTERED SHOWER AND THUNDERSTORM CHANCES WILL DIMINISH WITH THE
EXITING WAVE...BUT THE PATTERN REMAINS MODESTLY UNSETTLED INTO THE
END OF THE WORK WEEK...SO LEFT IN SOME SHOWER AND STORM CHANCES INTO
THURSDAY. TEMPERATURES WILL MODERATE SOME WITH THE RETURN OF A BIT
MORE SUNSHINE. HIGHS WILL GENERALLY BE IN THE 70S NEXT WEEK.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1209 PM CDT THU MAY 21 2015

VFR CONDITIONS THROUGH THE TAF PERIOD. GUSTY NORTHWEST WINDS THIS
AFTERNOON WILL QUICKLY DIMINISH THIS EVENING.


&&

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

$$

SHORT TERM...JM
LONG TERM...
AVIATION...JM


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