Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 290935
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
435 AM CDT SUN MAR 29 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 433 AM CDT SUN MAR 29 2015

WINDS AND IMPACT ON FIRE WEATHER CAPTURE FULL CONCERN FOR SHORT TERM
PORTION OF THE FORECAST.

LEADING UPPER ENERGY RACING THROUGH THE EASTERN CWA EARLY THIS
MORNING...TAKING SPOTTY LIGHT SHOWERS QUICKLY WITH IT. SOUTHERLY LOW
LEVEL JET WINDS REMAIN QUITE STRONG...WITH SURFACE GUSTS 40 TO 50
MPH IN PARTS OF SW MN AS SHOWERS PUSHED THROUGH...ALONG WITH SOME
BUFFALO RIDGE ENHANCEMENT. TO THE WEST...SURFACE FRONTAL BOUNDARY
MARKED ON SATELLITE BY A NARROW BAND OF CLOUDS EAST OF THE JAMES
RIVER VALLEY BACK TOWARD LOWER BRULE AREA. LEADING PRESSURE RISES
STARTING TO COLLAPSE MORE SOUTHWARD THROUGH NEBRASKA...SO A BIT OF
STABILIZATION IN CLEAR SLOT HAS ALLOWED LESSER WINDS FOR A TIME IN
MUCH OF SE SD.

HOWEVER...WINDS WILL GET ANOTHER BOOST THIS MORNING AS MAIN UPPER
TROUGH CURRENTLY SWINGING THROUGH NORTHWEST SOUTH DAKOTA RACES
EAST/SOUTHEAST EARLY THIS MORNING. SECONDARY AREA OF PRESSURE RISES
WILL AID THE 40-55KT NORTHWESTERLY JET IN DRASTICALLY INCREASING
WINDS DURING THE EARLY TO MID MORNING PERIOD...ROUGHLY ACCOMPANYING
INCREASE IN LOWER CLOUDS. THESE CLOUDS...AND AN AREA OF LIGHT
RAINFALL...WILL MAKE A STRONGER SOUTHWARD PUSH THAN PREVIOUSLY
EXPECTED DURING THE MORNING. WHILE LOWER TO MID LEVEL FRONTOGENETIC
PRECIPITATION BAND LOOKS TO MAKE INROADS EAST/SOUTHEAST...WILL BE
UNDERGOING A GRADUAL DISSIPATION AS IT SHEARS THROUGH AROUND MID TO
LATE MORNING. THEREFORE...EXPECT A LIMITED SOUTHWARD PUSH TO A LOWER
END MEASURABLE PRECIPITATION THREAT...PROBABLY NO FURTHER SOUTH THAN
I 90. TOTAL RAINFALL WILL BE FAIRLY MINIMAL...SEVERAL HUNDREDTHS AT
MOST ACROSS PARTS OF EAST CENTRAL SD AND NORTHERN SW MN.

WINDS WILL CERTAINLY BECOME STRONG ENOUGH TO SUPPORT A WIND
ADVISORY...BUT WILL EVEN HAVE TO WATCH THE BUFFALO RIDGE AREA FOR
OUTSIDE CHANCE OF HIGH WIND WARNING CONDITIONS AS MID MIXED LAYER
WINDS GET CLOSE TO STRONG ENOUGH LATER MORNING AND MIDDAY.  WINDS
WILL START TO DROP OFF FIRST IN THE WEST BY EARLY TO MID
AFTERNOON... WITH DROPOFF SLOWED A BIT BY MIXING.

THINGS SHOULD RAPIDLY QUIET DOWN THIS EVENING AS SURFACE RIDGE DROPS
INTO THE CENTRAL PLAINS. WITH DRY AIRMASS...EXPECT THAT LOWS TONIGHT
MAY DIP TOWARD COOLER END OF GUIDANCE ENVELOPE...ESPECIALLY LOWER
SPOTS...WITH TYPICAL WEAKENING GRADIENT FAVORING SOUTHWEST
DECOUPLING. INCREASE IN HIGHER CLOUDS ABOUT THE ONLY THING TO PUT
THE BRAKES ON RADIATIVE COOLING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 433 AM CDT SUN MAR 29 2015

DRY AND WARM CONDITIONS ARE EXPECTED FOR MONDAY/TUESDAY...AND HAVE
FAVORED WARMER SIDE OF GUIDANCE FOR AFTERNOON HIGHS BOTH DAYS GIVEN
STRONG MIXING POTENTIAL MONDAY...AND LACK OF WIDESPREAD MOISTURE OF
LATE TO KEEP THE SOILS MOIST...WHICH SHOULD AID IN WARMING EVEN IN
SLIGHTLY LESS FAVORABLE MIXING ON TUESDAY. THE BREEZIER WINDS AND
LOW HUMIDITY LEVELS MONDAY WILL LEAD TO VERY HIGH FIRE DANGER ACROSS
THE FORECAST AREA...WITH ONLY MODERATE TO HIGH FIRE DANGER TUESDAY
AS SURFACE RIDGE BRINGS MUCH LIGHTER WINDS TO THE REGION.

COLD FRONT STILL ON TRACK TO PUSH THROUGH THE FORECAST AREA ON
WEDNESDAY...PRECEDED BY INCREASING LOW LEVEL MOISTURE AND GUSTY
SOUTHWEST WINDS. NOSE OF ELEVATED INSTABILITY EXTENDS INTO THE
CENTRAL/EASTERN CWA BY DAYBREAK WEDNESDAY. FAIRLY STOUT CAP TO
OVERCOME...BUT CANNOT RULE OUT SOME ACCAS SHOWERS WEDNESDAY MORNING.
BETTER CHANCE OF PRECIP WILL BE AHEAD OF THE SURFACE FRONT WEDNESDAY
AFTERNOON...AND THIS SHOULD BE FOCUSED ACROSS THE SOUTHEAST HALF OF
THE CWA. ECMWF ON THE SLOWER SIDE WITH TIMING...AND HAVE THUS FAR
FAVORED THE FASTER GFS/GEM. SHOULD BE A DECENT THUNDER POTENTIAL
WITH BOTH GFS/ECMWF SHOWING CAPE VALUES GREATER THAN 1000J/KG AHEAD
OF THE BOUNDARY.

BROAD MID LEVEL TROUGH REMAINS OVER THE REGION THURSDAY...THEN
BEGINS TO SHIFT EASTWARD FOR FRIDAY/SATURDAY. MAIN QUESTION FOR
PRECIP CHANCES LATE IN THE WEEK WILL BE HOW FAR SOUTH WEDNESDAY`S
COLD FRONT WILL PUSH THROUGH THE PLAINS AS A SECONDARY WAVE TRACKS
OUT OF THE CENTRAL ROCKIES. GEM REMAINS FARTHER NORTH...AND THUS
SPREADS FAIRLY DECENT CHANCE OF RAIN INTO THE SOUTHERN HALF OF OUR
FORECAST AREA THURSDAY NIGHT/FRIDAY. 00Z ECMWF HAS TRENDED FARTHER
SOUTH LIKE THE GFS...KEEPING OUR AREA PRETTY MUCH DRY THROUGH THE
LATTER PART OF THE WEEK. WILL HANG ONTO SOME LOW POPS IN THE SOUTH
TO ACCOUNT FOR UNCERTAINTY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 607 PM CDT SAT MAR 28 2015

A STRONG COLD FRONT WILL PUSH ACROSS THE AREA LATER
TONIGHT...WITH A 50 TO 60 KT LOW LEVEL JET DEVELOPING OUT AHEAD OF
THE BOUNDARY. THIS WILL RESULT IN A FEW HOURS OF LOW LEVEL WIND
SHEAR AT ALL THE TAF SITES. THERE WILL ALSO BE A POSSIBILITY OF
ISOLATED SHOWERS WITH THE BOUNDARY...MAINLY NORTH OF THE
INTERSTATE 90 CORRIDOR...AND VERY STRONG WINDS COULD BRIEFLY MIX
DOWN TO THE SURFACE WITH THESE SHOWERS. OTHERWISE...STRONG
NORTHWESTERLY WINDS WILL DEVELOP BEHIND THE FRONT...GUSTING TO
AROUND 40 KTS THROUGH MUCH OF THE DAY ON SUNDAY.


&&

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

NOT QUITE AS STRAIGHTFORWARD ISSUES WITH FIRE WEATHER TODAY. SOME
OF THE STRONGEST WINDS MAY ACTUALLY OCCUR DURING THE LATER MORNING
AS AREA OF LOWER CLOUDS MOVES THROUGH...AND RH LIKELY TO GET A BIT
OF A BOOST WITH SECONDARY AREA OF VERY LIGHT RAINFALL SLIDING
THROUGH EAST CENTRAL SD AND SW MN MID TO LATE MORNING. ANY CLOUDS
AND PRECIP WILL COME TO A QUICK DEMISE BY LATE MORNING...LEAVING
SUN AND WIND TO WORK ON THE REST OF THE DAY.

DECIDED TO GO WITH THE RED FLAG WARNING IN THOSE AREAS WHERE LOWEST
HUMIDITY GETS CLOSE TO OR EXCEEDS 20/25 PERCENT CRITERIA...WITH
STRONG WINDS THE DECIDING FACTOR ON PUSHING MARGINAL CONDITIONS.
DESPITE FACT THAT LOWEST HUMIDITY AND STRONGEST WINDS WILL BE
SOMEWHAT OFF TIMED IN THE LOWER BRULE AREAS. ELSEWHERE...AFTER
COORDINATION CALL HAVE MAINTAINED WATCH FOR EAST CENTRAL SD...SW
MN...AND IOWA GREAT LAKES AREA IN NW IA WHERE LOWEST HUMIDITY IS
MUCH MORE HIGHLY IN QUESTION...CURRENTLY EXPECTED TO REMAIN 30 TO 38
PERCENT. ALSO HAVE WILD CARD OF MORNING RAINFALL MOVING THROUGH THE
NORTHERN AND EASTERN FIRE WEATHER ZONES. ALBEIT EXPECTATIONS OF VERY
LIGHT PRECIPITATION...SHOULD BE SUFFICIENT WITH WIND AND SUBSIDENCE
TO ALTER FINE FUELS FAST ENOUGH TO MATTER. EXTREME FIRE DANGER TODAY
FOR ALL AREAS.

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 25 PERCENT OVER MUCH OF THE
THE AREAS. FIRE DANGER WILL BE VERY HIGH THROUGHOUT THE AREA...BUT
COULD APPROACH EXTREME IF WINDS BECOME SLIGHTLY STRONGER THAN
FORECAST.

STRONG PRE AND POST-FRONTAL WINDS ON WEDNESDAY WILL LEAD TO VERY
HIGH FIRE DANGER AT SOME POINT DURING THE DAY THROUGHOUT THE CWA.
THE FIRE DANGER SHOULD DECREASE ACROSS NORTHWEST IOWA DURING THE
AFTERNOON AS THE FRONT MOVES IN AND BRINGS A DECREASE IN WINDS AND
INCREASE IN PRECIP THREAT THOUGH. DEEP NORTHWEST FLOW WILL DOMINATE
ACROSS THE AREA THURSDAY WHICH SHOULD AGAIN BE FAVORABLE FOR MIXING
DOWN SOME HIGHER WIND GUSTS AND LOWER DEW POINTS IN THE AFTERNOON.
THIS WILL LEAD TO ANOTHER DAY OF VERY HIGH FIRE DANGER FOR MOST
AREAS.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 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.

     WIND ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR SDZ038-039-050-
     052>054-057>060-063>065-068.

     FIRE WEATHER WATCH FROM 1 PM CDT THIS AFTERNOON THROUGH 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 FROM 1 PM CDT THIS AFTERNOON THROUGH THIS
     EVENING FOR MNZ900.

IA...RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 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 FROM 1 PM CDT THIS AFTERNOON THROUGH THIS
     EVENING FOR IAZ301.

NE...RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 7 PM CDT THIS
     EVENING FOR NEZ249.

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

&&

$$

SHORT TERM...CHAPMAN
LONG TERM...JH
AVIATION...JM
FIRE WEATHER...CHAPMAN/JH


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