Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 201811
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
111 PM CDT MON APR 20 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CDT MON APR 20 2015

TODAY IS STILL LOOKING TO BRING AN EXTREMELY MIXED ENVIRONMENT WHICH
WILL BE GOOD FOR DRYING AND STRONGER THAN GUIDANCE WINDS GETTING TO
THE SURFACE. IT WILL ALSO BRING A FEW LIGHT SHOWERS TO THE AREA
NORTH TO EAST OF FSD WHERE THERE WILL BE ENOUGH MOISTURE TO DEVELOP
THEM AND GET A COUPLE MINUSCULE MEASURABLE AMOUNTS TO THE SURFACE.
THE STRONG MIXING MAKES AN OTHERWISE MARGINAL WIND ADVISORY DAY INTO
AN EASY DECISION TO GO FOR ONE FOR ALL OF THE FORECAST AREA. HIGH
TEMPERATURES TODAY ARE BEING MOVES UP A TAD FROM THE EARLIER
FORECAST TO ALLOW FOR THE STRONG MIXING. HIGHS FROM 50 NORTHEAST TO
UPPER 50S SOUTHWEST.

WINDS WILL DECREASE THIS EVENING BUT WITH A STEADY BREEZE PERSISTING
LATE TONIGHT. THE WIND DROP OFF SHOULD BE ENOUGH TO ALLOW
TEMPERATURES TO COOL TO A LITTLE BELOW FREEZING EXCEPT FAR NORTHEAST
WHERE THE WIND WILL HOLD UP BETTER. ANY SHOWERS WILL END AT THE
START OF THE EVENING AND LINGERING CLOUDS NORTHEAST WILL ONLY VERY
SLOWLY DECREASE.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 342 AM CDT MON APR 20 2015

COOL AND DRY CONDITIONS WILL PREVAIL IN THE MEDIUM RANGE AS THE SLOW
MOVING UPPER LEVEL TROUGH COVERING THE CANADIAN AND NORTHERN US
GREAT PLAINS GRADUALLY SHIFTS EASTWARD...REACHING THE EASTERN GREAT
PLAINS ON THURSDAY. WITH NORTHWEST FLOW LOCKED IN...DRY WEATHER AND
MOSTLY CLEAR SKIES CAN BE EXPECTED ALONG WITH TEMPERATURES SLIGHTLY
COOLER THAN NORMAL. NIGHTTIME TEMPERATURES WILL BE A CONCERN WITH
LOWS DROPPING BELOW FREEZING ACROSS THE FORECAST AREA TUESDAY
NIGHT...AND ONLY IMPROVING A FEW DEGREES ON WEDNESDAY NIGHT. WITH
THE GROWING SEASON ALREADY IN PROGRESS...THERE WILL BE FROST AND
FREEZE CONCERNS BOTH NIGHTS...ALTHOUGH THE PARTICULARLY DRY AIRMASS
MAY MITIGATE THE FROST SOME.

ADDITIONALLY...TUESDAY WILL SEE FAIRLY WINDY CONDITIONS PARTICULARLY
ACROSS OUR EASTERN HALF WHERE NEAR ADVISORY LEVEL WINDS WILL BE
POSSIBLE. THE WELL MIXED CONDITIONS WILL LEAD TO FIRE WEATHER
CONCERNS AS VERY DRY DEWPOINTS MIX DOWN AND COMBINE WITH THE STRONG
WINDS. HUMIDITY VALUES SHOULD EASILY REACH LESS THAN 25 PERCENT FOR
MOST OF THE FORECAST AREA...SO HEADLINES WILL LIKELY NEED TO BE
HOISTED. WINDS ON WEDNESDAY DO DECREASE A BIT WHICH WILL LESSEN FIRE
CONCERNS...BUT HUMIDITY DROPS EVEN LOWER...SO WILL NEED TO CONTINUE
TO MONITOR.

BY LATE WEEK...THE PATTERN BEGINS BREAKING DOWN AS A BROAD WESTERN
TROUGH BEGINS DIRECTING SEVERAL WAVES INTO THE CENTRAL PLAINS
THURSDAY NIGHT INTO THE WEEKEND. WHILE ALL MODELS DO SHOW ACTIVE
WEATHER DURING THIS PERIOD...THERE IS SOME UNCERTAINTY ON THE
TIMING...STRENGTH AND HOW FAR NORTH THESE WAVES WILL TRACK. THE GFS
IS THE MOST PROGRESSIVE AND FURTHEST NORTH...BRINGING RAIN SHOWERS
INTO THE CENTRAL AND SOUTHERN FORECAST AREA. THE GEM HOWEVER KEEPS
THIS ACTIVITY LARGELY SOUTH OF THE FORECAST AREA...WHILE THE ECMWF
IS THE DEEPEST AND SLOWEST SOLUTION. LOOKS LIKE THE BEST POTENTIAL
FOR SHOWERS WILL BE ACROSS OUR SOUTH...BUT WITH SOME TIMING AND
LOCATION CONCERNS AS WELL AS RUN TO RUN INCONSISTENCIES...WILL LEAVE
ONLY SLIGHT CHANCE OR CHANCES SIMILAR TO ALL BLEND TIMING.
TEMPERATURES THIS WEEKEND PERSIST AT SLIGHTLY BELOW NORMAL AND
GENERALLY IN THE 50S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 110 PM CDT MON APR 20 2015

VFR CONDITIONS EXPECTED INTO TUESDAY. NORTHWEST WINDS WILL
CONTINUE TO GUST ABOVE 35 KNOTS INTO THE AFTERNOON HOURS...BEFORE
WEAKENING OVERNIGHT. A WEAK SURFACE TROUGH WILL SWING THROUGH
EARLY TUESDAY MORNING...WITH WINDS AGAIN PICKING UP BY THE LATE
MORNING HOURS.

&&

.FIRE WEATHER...
VERY HIGH TO EXTREME FIRE WEATHER TODAY AND WILL KEEP THE RED FLAG
WARNING AS IS FOR ALL OF OUR SOUTH DAKOTA COUNTIES. AS WE HAVE BEEN
DISCUSSING HERE...SATURDAY RAIN OF A HALF INCH PLUS WILL BE GIVEN
THE TIPPER ON KEEPING THE RED FLAG WARNING OUT OF NORTHWEST
IOWA...WHERE CONDITIONS OVER THE SOUTHWEST PART OF THAT AREA MIGHT
OTHERWISE BE JUST DRY ENOUGH WITH THE WINDS TO GO FOR ONE.
STILL...FIRE DANGER WILL PROBABLY BE VERY HIGH THERE. THE RED FLAG
WARNING WILL CONTINUE TO GO FROM NOON TO 8 PM CDT.

FIRE WEATHER CONCERNS ARE AGAIN EXPECTED ON TUESDAY WITH WINDS
AVERAGING 15 TO 30 MPH AND HUMIDITY DROPPING BELOW 25 PERCENT
ACROSS THE ENTIRE FORECAST AREA. THE LOW HUMIDITY CONTINUES INTO
WEDNESDAY BUT THE WINDS ARE EXPECTED TO BE LIGHTER IN THE 10 TO 20
MPH RANGE.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR SDZ255>258.

     WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR SDZ038>040-050-
     052>071.

MN...WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR MNZ071-072-080-081-
     089-090-097-098.

IA...WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR IAZ001>003-012>014-
     020>022-031-032.

NE...WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR NEZ013-014.

&&

$$

SHORT TERM...
LONG TERM...
AVIATION...DUX
FIRE WEATHER...


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