Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 101145
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
645 AM CDT THU APR 10 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT THU APR 10 2014

EARLY THIS MORNING A BAND OF VERY LIGHT RAIN AND SPRINKLES WILL MOVE
THROUGH AND SHOULD EXIT THE CWA BY ABOUT 16Z. FORCING IN THE
DENDRITIC LAYER REALLY CAPTURES THIS AREA OF PRECIPITATION WELL BUT
WITH FAIRLY DRY CONDITIONS IN THE LOWEST 5000 FEET ONLY ANTICIPATING
SPRINKLES OR MAYBE A ROGUE HUNDREDTH. CLOUDS WILL CLEAR FROM
NORTHWEST TO SOUTHEAST THROUGH THE MORNING SETTING UP A SUNNY AND
MILD DAY...ALBEIT JUST A BIT BREEZY. HIGHS SHOULD MAINLY BE IN THE
60S. BY TONIGHT WINDS WILL DROP OFF AND TURN TO THE SOUTHWEST AT
ABOUT 5 TO 15 MPH. A WEAK MID LEVEL WAVE WITH VERY MARGINAL
INSTABILITY WILL BRING SPOTTY SHOWER COVERAGE BUT AMOUNTS WILL AGAIN
BE PRETTY LIGHT AND COVERAGE IN THE ISOLATED TO LOWER END SCATTERED.
LOWS WILL MAINLY BE IN THE UPPER 30S TO LOWER 40S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 406 AM CDT THU APR 10 2014

A MILD AND MOSTLY SUNNY DAY IS EXPECTED ON FRIDAY. LOW LEVEL THERMAL
PROFILES WARM A BIT FROM THURSDAY...AND WITH EXCELLENT MIXING AGAIN
EXPECTED...HIGHS SHOULD BE SEVERAL DEGREES WARMER. STAYED CLOSE TO
THE WARMER BIAS CORRECTED VALUES...WITH UPPER 60S TO MID 70S COMMON.
IT WILL BE A BIT BREEZY AS WELL...WITH GUSTS INTO THE 20 TO 30 MPH
RANGE OUT OF THE WEST. THE WEATHER BEGINS TO BECOME MORE ACTIVE
FRIDAY NIGHT INTO THE WEEKEND. LOW LEVEL JET INCREASES FRIDAY NIGHT
ADVECTING HIGHER THETAE AIR INTO THE REGION. HOWEVER THE BEST DEEP
LAYER MOISTURE AND LARGE SCALE LIFT WILL REMAIN NORTH OF OUR CWA.
THUS QUESTION BECOMES WHETHER WE SEE SHOWER AND THUNDERSTORMS BUILD
SOUTH INTO THE LOW LEVEL JET...OR IF THE DRY AIR WINS OUT. ECMWF HAS
CONSISTENTLY SHOWN QPF FURTHER SOUTH...WITH THE GFS AND GEM MAINLY
NORTH. FOR NOW WILL NOT MAKE MANY CHANGES TO THE FORECAST...KEEPING
CHANCE POPS GOING...HIGHEST IN SOUTHWEST MINNESOTA CLOSER TO THE
BETTER FORCING AND MOISTURE. LOOKS LIKE WE MAY HAVE ENOUGH ELEVATED
INSTABILITY TO AT LEAST SEE SCATTERED THUNDER IF ANYTHING DOES FORM.

THE COLD FRONT WILL THEN PUSH ACROSS ON SATURDAY. COOLER AIR LAGS
THE WIND SHIFT...SO EVEN WITH THE FRONT THROUGH MOST OF THE CWA BY
AFTERNOON...IT SHOULD STILL BE A WARM ONE. THUS BUMPED HIGHS UP A
FEW MORE DEGREES...WITH UPPER 60S TO UPPER 70S EXPECTED. MAY STILL
BE A FEW DEGREES TOO COOL. BUT WITH SOME UNCERTAINTY ON TIMING OF
THE COLDER AIR AND POTENTIAL CLOUD COVER ISSUES DID NOT WANT TO GO
TOO HIGH JUST YET. STILL LOOKS LIKE WE SHOULD SEE SHOWER AND
THUNDERSTORM DEVELOPMENT ALONG AND JUST AHEAD OF THE FRONT DURING
THE AFTERNOON HOURS. INSTABILITY AND SHEAR AHEAD OF THE FRONT DO
APPEAR STRONG ENOUGH TO SEE SOME STRONG TO SEVERE THUNDERSTORMS. SO
WILL HAVE TO MONITOR TRENDS IN TIMING OF THIS FRONTAL BOUNDARY
THROUGH THE CWA. AT THIS TIME MODEL CONSENSUS CONTINUES TO SUGGEST
MOST OF THIS THUNDERSTORM ACTIVITY WILL BE SOUTH OF THE CWA...WITH
MAYBE SIOUX CITY TO JACKSON STAYING AHEAD OF THE BOUNDARY LONG
ENOUGH TO SEE STORM DEVELOPMENT.

MODELS BECOMING MORE CONSISTENT IN HOW THEY HANDLE THE NORTHERN AND
SOUTHERN STREAM INTERACTION IN THE TROUGH SATURDAY NIGHT INTO
SUNDAY. THEY ARE CONVERGING ON A MORE PROGRESSIVE SOUTHERLY
TRACK...WHICH MEANS PRECIPITATION SATURDAY NIGHT INTO SUNDAY SHOULD
GENERALLY STAY ALONG INTERSTATE 90 AND POINTS SOUTH...WITH THE BEST
CHANCES ALONG THE MISSOURI RIVER. ANY PRECIPITATION THAT DOES FALL
WILL BE A COLD RAIN. HIGHS ONLY IN THE 40S ON SUNDAY WITH A BLUSTERY
NORTHERLY WIND...SO NOT THE BEST OF DAYS. OF COURSE WILL NEED TO
CONTINUE TO MONITOR MODEL TRENDS ON HOW THEY HANDLE THIS SYSTEM. A
QUICKER PHASE AND THUS TREND NORTHWEST WOULD BRING THE THREAT OF SOME
SNOW BACK INTO THE FORECAST SUNDAY...BUT AGAIN RECENT INDICATIONS
SUGGEST THIS IS A PRETTY LOW PROBABILITY EVENT AT THIS TIME.

WITH THE MAIN TROUGH AXIS SWINGING ACROSS ON MONDAY WE WILL REMAIN
COOL. SHOULD STAY DRY WITH A LACK OF MOISTURE BUT HIGHS AGAIN ONLY
EXPECTED TO BE IN THE 40S. NOT EXPECTING MUCH WARMING TUESDAY OR
WEDNESDAY EITHER AT THIS TIME...WITH 40S TO AROUND 50 MOST PROBABLE.
MODEL SOLUTIONS BEGIN TO DIVERGE BY WEDNESDAY AS TROUGHING MOVES
BACK INTO THE WESTERN PORTION OF THE COUNTRY. THE GFS DEVELOPS
OVERRUNNING PRECIPITATION OVER THE CWA TUESDAY NIGHT INTO
WEDNESDAY...WITH THE ECMWF DRY. JUST STAYED CLOSE TO A CONSENSUS FOR
THIS PERIOD GIVEN THE HIGH UNCERTAINTY. IT DOES LOOK LIKE ANOTHER
ACTIVE PERIOD TO END THE WEEK THOUGH...JUST TOO EARLY TO PIN DOWN
THE EXACT EVOLUTION...LOCATION AND TIMING OF ANY PRECIPITATION.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 645 AM CDT THU APR 10 2014

VFR THROUGH THE PERIOD.

&&

.FIRE WEATHER...

WHILE TODAY WILL END UP ABOUT 15 DEGREES COOLER THAN
YESTERDAY...STRONG WINDS AND LOW AFTERNOON HUMIDITIES WILL LEAD TO
ANOTHER DAY OF POTENTIALLY DANGEROUS FIRE WEATHER. THE MOST AFFECTED
AREAS WILL BE SOUTHWEST MINNESOTA WHERE SUSTAINED WINDS OF ABOUT 20
TO 25 MPH WITH GUSTS AROUND 30 MPH WILL COMBINE WITH HUMIDITY VALUES
OF 20 TO 25 PERCENT TO CREATE RED FLAG CONDITIONS THIS AFTERNOON. A
BUFFER ZONE NEAR SOUTHWEST MINNESOTA...EXTREME EASTERN SOUTH DAKOTA
INTO FAR NORTHWEST IOWA WILL COME CLOSE TO HITTING RED FLAG CRITERIA
BUT BELIEVE WINDS WILL BE JUST LOW ENOUGH TO STAY IN THE VERY HIGH
CATEGORY. THESE AREAS WILL NEED TO BE MONITORED HOWEVER.

ANOTHER DAY OF VERY HIGH FIRE DANGER EXPECTED ON FRIDAY. DEEP MIXING
WILL RESULT IN AFTERNOON RELATIVE HUMIDITY VALUES DROPPING INTO THE
15 TO 25 PERCENT RANGE. AT THIS TIME...WINDS DO NOT APPEAR STRONG
ENOUGH TO WARRANT A RED FLAG WARNING...BUT IT WILL BE CLOSE. THUS
WILL NEED TO CONTINUE TO MONITOR THE SITUATION.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...RED FLAG WARNING FROM NOON TODAY TO 7 PM CDT THIS EVENING FOR
     MNZ900.

IA...NONE.
NE...NONE.
&&

$$

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






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