Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 291949
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
249 PM CDT SUN MAR 29 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 248 PM CDT SUN MAR 29 2015

NORTHWESTERLY WINDS ARE ON THE DOWNWARD TREND ACROSS THE AREA.
EXPECT FIRE WEATHER TO BE A CONCERN THROUGH THE REMAINDER OF THE
AFTERNOON...BUT SHOULD RAPIDLY IMPROVE TOWARDS SUNSET AS MIXING COMES
TO AN END.  CLEAR SKIES AND LIGHT WINDS SHOULD LEAD TO GOOD
RADIATIVE CONDITIONS ACROSS THE AREA.  HAVE ELEVATION SHADOW IN THE
LOWS OVERNIGHT...THOUGH SOUTHWEST FLOW KICKS IN AFTER MIDNIGHT.  IF
THE INVERSION IS NOT ABLE TO ESTABLISH ITSELF WELL ENOUGH
OVERNIGHT...COULD SEE TEMPERATURES FLOUNDER AFTER MIDNIGHT AS HIGH
CLOUDS SPREAD FROM WEST TO EAST.

NICE MIXY DAY ACROSS THE AREA ON MONDAY WITH WESTERLY WINDS MIXING
DOWN FROM ALOFT.  THIS SHOULD LEAD TO GUSTY CONDITIONS...AND DRY AIR
MIXING DOWN FROM ALOFT.  WITH RH VALUES FALLING TO 20 TO 30
PERCENT...EXPECT CONDITIONS TO APPROACH RED FLAG BUT FALL SHORT ON
THE WIND CRITERIA.  HAVE MENTION IN THE HWO...AND IN THE FIREWEATHER
SECTION BELOW.  SHOULD MIX TO 750-800 MB...YIELDING 60S AND 70S
ACROSS THE AREA. SIDED WITH WARMER GUIDANCE VALUES GIVEN THE GOOD
MIXING CONDITIONS AND DRY CONDITIONS AS OF LATE.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 248 PM CDT SUN MAR 29 2015

MONDAY NIGHT INTO TUESDAY WILL SEE A WEAK BOUNDARY WORK INTO THE
AREA WITH MOST OF THE EFFECTS OVER THE EASTERN CWA. STILL EXPECTING
VERY NICE TEMPERATURES AND WITH THIS WEAK HIGH PRESSURE WINDS WILL
BE ON THE LOWER SIDE SO HIGHS FROM THE MID 60S TO MID 70S WILL FEEL
VERY NICE.

TUESDAY NIGHT THE LOW LEVEL JET WILL SIGNIFICANTLY INCREASE AHEAD
OF THE INCOMING WAVE. AT THIS TIME NOT ENOUGH MOISTURE TO
NECESSITATE A CHANCE FOR SHOWERS OR THUNDERSTORMS BUT IF A LITTLE
MORE MOISTURE ALOFT CAN SNEAK INTO THE SYSTEM WE COULD SEE SOME
SCATTERED CONVECTION OVER THE NORTHEAST THIRD OF THE CWA. OTHERWISE
WITH THE STRONG WINDS OVERNIGHT EXPECTING VERY MILD TEMPERATURES
ONLY FALLING INTO THE LOWER 50S IN MOST LOCATIONS.

WEDNESDAY INTO WEDNESDAY NIGHT STILL LOOKS THE MOST INTERESTING WITH
A DECENT CHANCE FOR THUNDERSTORMS OVER MAINLY NORTHWEST IOWA.
MOISTURE AND INSTABILITY WILL BE THE BIG QUESTION AS CONVECTIVE
INITIATION WILL BE GREATLY TIED TO HOW MUCH MOISTURE CAN SNEAK IN AT
THE LOW LEVELS. IF MODELS ARE OVERDOING BY JUST A FEW DEGREES ON LOW
LEVEL DEW POINTS WE COULD EASILY SEE A DRY FRONTAL PASSAGE. BUT FOR
NOW WILL HAVE CHANCE POPS IN THE SOUTHEAST. PLENTY OF SHEAR TO
SUPPORT AN ISOLATED SEVERE THUNDERSTORM BUT JUST A BIT WORRIED THAT
INSTABILITY WILL BE A LITTLE TOO LOW. FOR NOW JUST KEEP IT AS A
MENTION OF THUNDERSTORMS.

IN THE OUTER PERIODS(THURSDAY THROUGH SUNDAY)...FAIRLY STRONG LOW
PRESSURE TRACKS EAST ALONG THE CANADIAN BORDER ON THURSDAY WHICH WILL
ALLOW COOLER AND DRIER AIR TO FILTER INTO THE REGION. HOWEVER IT
APPEARS TO BE A BIT OF A GLANCING BLOW WITH THE COLDEST AIR
REMAINING OFF TO THE NORTH AND EAST. A WEAKER TROUGH WILL MOVE OUT
OF THE CENTRAL ROCKIES AND HELP KEEP THE COOLER AIR TO THE NORTHEAST
ON FRIDAY WHILE ANOTHER STRONG SURGE OF COLD AIR TRIES TO WORK SOUTH
OUT OF CANADA ON SATURDAY AS A FAIRLY STRONG LOW PRESSURE SYSTEM
MOVES SOUTHEAST INTO THE NORTHERN UNITED STATES. ONCE AGAIN THE
MODELS ARE A LITTLE LESS BOISTEROUS WITH THE SURGE OF COLD AIR.
ENOUGH DISAGREEMENT AMONGST MODELS HOWEVER WILL KEEP THE FORECAST
MIDDLE OF THE ROAD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1247 PM CDT SUN MAR 29 2015

MVFR CLOUDS BEHIND A COLD FRONT SHOULD SCATTER OUT AND GRADUALLY
CLEAR ACROSS NORTHWEST IOWA. OTHERWISE...THE PRIMARY ISSUE ARE THE
STRONG NORTHWEST WINDS. THE GUSTY WINDS SHOULD RAPIDLY DECREASE
TONIGHT...AND REMAIN LIGHT THROUGH THE OVERNIGHT. WINDS WILL
INCREASE AND BECOME MARGINALLY GUSTY AFTER 15Z MONDAY.


&&

.FIRE WEATHER...
ISSUED AT 433 AM CDT SUN MAR 29 2015

FIRE WEATHER CONDITIONS SHOULD RAPIDLY IMPROVE THIS EVENING AS WINDS
RAPIDLY DECREASE WITH SUNSET.  RELATIVE HUMIDITY VALUES WILL ALSO
RECOVER AS TEMPERATURES DECREASE.

WESTERLY FLOW ON MONDAY SHOULD FAVOR STRONG MIXING...RESULTING IN
AFTERNOON WIND GUSTS TO AROUND 25 MPH OR SLIGHTLY HIGHER...ALONG
WITH MINIMUM HUMIDITY LEVELS FROM 20 TO 30 PERCENT OVER MUCH OF THE
THE AREA. FIRE DANGER WILL BE VERY HIGH THROUGHOUT THE AREA...BUT
COULD APPROACH EXTREME IF WINDS BECOME SLIGHTLY STRONGER THAN
FORECAST.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR SDZ255-256-258.

     WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR SDZ040-055-056-061-
     062-066-067-069>071.

     FIRE WEATHER WATCH UNTIL 7 PM CDT THIS EVENING FOR SDZ257.

MN...WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MNZ071-072-080-081-
     089-090-097-098.

     FIRE WEATHER WATCH UNTIL 7 PM CDT THIS EVENING FOR MNZ900.

IA...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR IAZ300.

     WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ001>003-012>014-
     020>022-031-032.

     FIRE WEATHER WATCH UNTIL 7 PM CDT THIS EVENING FOR IAZ301.

NE...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR NEZ249.

     WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NEZ013-014.

&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...
FIRE WEATHER...


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