Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 291706
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1206 PM CDT FRI APR 29 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT FRI APR 29 2016

TODAY WILL ACTUALLY BE FAIRLY QUIET WEATHER WISE...AS A SUBTLE UPPER
RIDGE MOVES THROUGH THE FORECAST AREA. A DRY LOW LEVEL FETCH OF AIR
MOVES DOWN FROM THE NORTH AND NORTHEAST COURTESY OF HIGH PRESSURE IN
SOUTH CENTRAL CANADA. IN FACT...HAVE SOME PARTIAL CLEARING TAKING
PLACE IN OUR NORTHEAST ZONES THIS AFTERNOON AND EVENING...WITH ONLY
HIGH CLOUDS DOMINATING AREAS AS CLOSE AS CENTRAL MINNESOTA AND
SOUTHEAST NORTH DAKOTA. SOME OTHER LOCATIONS COULD ALSO SEE A BIT OF
AFTERNOON SUNSHINE...HOWEVER THE FURTHER YOU HEAD SOUTHWEST...IT
WILL BE TOUGH TO CLEAR OUT AREAS GENERALLY ALONG OUR MO RIVER VALLEY
ZONES. BECAUSE OF THIS SCENARIO...HAVE THE WARMEST HIGHS TODAY
AROUND MARSHALL MN WHO SHOULD REACH THE UPPER 50S AFTER ADDING
A COUPLE OF DEGREES TO CONSENSUS GUIDANCE READINGS. CONVERSELY...
CONTINUED A TREND OF GOING WITH CHILLY RAW MODEL VALUES ELSEWHERE
WHERE MORE CLOUDS WILL DOMINATE...COOLING THINGS OFF TO THE UPPER
40S IN OUR SOUTH CENTRAL SD ZONES.

TONIGHT...THE NEXT UPPER LOW TO INFLUENCE OUR WEATHER MOVES INTO
EASTERN CO AND WESTERN KS. MID AND UPPER LEVEL QG FORCING MOVES INTO
OUR SOUTHERN ZONES BY LATE TONIGHT...ALONG WITH FAIRLY STRONG
FRONTOGENETIC FORCING IN THE LOW LEVELS AND POSITIVE THETAE
ADVECTION FROM I 90 SOUTHWARD. THE ONE THING TO WATCH FOR HOWEVER IS
THE 850-700MB STREAMLINES ARE STILL DECIDEDLY USHERING IN A DRY FETCH
OF AIR FROM THE NORTHEAST ALL NIGHT. NOTICED THAT THE 06Z NAM HAS
REVERTED TO A DRIER FORECAST FOR EVEN OUR SOUTHERN ZONES...MUCH MORE
SIMILAR TO THE GFS. IN ADDITION...THE NMM IS FAVORING A 06Z NAM
SOLUTION AND THE ARW IS FURTHER SOUTH YET. THEREFORE IT COULD TAKE A
LONG TIME FOR THE RAINFALL TO DRIFT NORTHWARD AS IT ENCOUNTERS THE
LIMITING STREAMLINES EDGING DOWN FROM SOUTH CENTRAL CANADA. HAVE A
SHARP POP GRADIENT...WITH THE NORTHERN EXTENT OF THE MEASURABLE
CHANCES FOR RAIN SOUTH OF EAST CENTRAL SD AND SOUTHWEST MN. THE
BEST CHANCES FOR MEASURABLE RAIN WILL OCCUR IN OUR MO RIVER VALLEY
ZONES AND A BIT NORTH OF THERE WHERE THE MOISTURE PROFILE IS DEEP
AND THE AFOREMENTIONED DYNAMICS COME INTO PLAY. DUE TO CLOUD
COVER...TRENDED LOWS TOWARD RAW MODEL CONSENSUS VALUES WHICH WERE
MORE MILD THEN OTHER READINGS.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 408 AM CDT FRI APR 29 2016

MAIN SYSTEM TO IMPACT WEATHER IN THE LONGER RANGE IS FRONT LOADED
THIS WEEKEND...AS FINAL OF THREE CLOSED UPPER LOWS WILL MOVE THROUGH
THE PLAINS. UPPER LOW TRACK THIS TIME IS FURTHER SOUTH THAN LAST
COUPLE OF SYSTEMS...GENERALLY VARYING FROM MOST NORTH SOLUTION IN
ECMWF TAKING CENTER NEAR I-80...WHILE GFS IS MOST SOUTHERN WITH CORE
OF FEATURE CLOSER TO I-70.  IN GENERAL...MAJORITY OF SOLUTIONS ARE
SOLID ON BRINGING BETTER RAIN CHANCES TO AREAS NEAR/SOUTH OF I-90...
AND LIMITING STREAMLINES 850-700 HPA INDICATE MORE THAN A BIT OF A
STRUGGLE TO GET PRECIP ALL THE WAY TO HIGHWAY 14 /HURON - MARSHALL/.
GENERAL TREND IN EARLIER FORECAST MAINTAINED...JUST A BIT SHARPER ON
THE NORTHERN EXTENT. NOT OUT OF THE QUESTION TO GET A ROGUE RUMBLE
INTO THE KSUX/KSLB AREAS BY MIDDAY OR EARLY AFTERNOON SATURDAY...BUT
CHANCE IS WELL BELOW THRESHOLD TO MENTION. SAFE TO SAY THAT
SATURDAY WILL GENERALLY BE LESS THAN PLEASANT...WITH NORTHEAST WINDS
GUSTING AS HIGH AS 30 TO 40 MPH...AND TEMPERATURES GENERALLY IN THE
UPPER 40S DURING PRECIP. WARMEST READINGS LIKELY ALONG THE NORTHERN
TIER FROM KHON TO KMML...LAST TO SEE RAIN IF AT ALL...AND LIKELY
CLOSE TO 900 HPA MIXING VALUES IN MID 50S.

SLOWLY FILLING UPPER WAVE PASSING SOUTH OF THE AREA ON SATURDAY
NIGHT...AND ADVECTIONS QUICKLY NEUTRALIZE ANY BETTER CHANCES
FOR ADDED PRECIPITATION BY NIGHTS END. DRIER AIR ADVECTING IN FROM
THE NORTHEAST TOWARD THE SURFACE...HELPING TO ACCELERATE THE
INCREASINGLY SOUTHWARD FOCUS TO DEFORMATION BAND. SPOTTY LIGHT
RAINFALL MAY LINGER INTO SUNDAY CLOSER TO U.S. HIGHWAY 20...BUT ANY
LINGERING FORCING IS OVER VERY EARLY. POTENTIAL FOR RAINFALL TOTALS
VARYING FROM MORE THAN AN INCH SOUTH OF AN ACADEMY TO STORM LAKE
LINE...AND LESS THAN A TENTH OF AN INCH TOWARD HIGHWAY 14.

LIKELY TO BE A FLAT STRATOCUMULUS FIELD ON SUNDAY...AS TEMPERATURES
MODERATE SOME INTO THE UPPER 50S TO LOWER 60S. KEPT AWAY FROM
SLIGHTLY WARMER MIXED VALUES DUE TO RECENT WIDESPREAD RAINFALL.

WELL-DESERVED DRYING AND WARMING ON TRACK FOR NEXT WEEK...AS UPPER
TROUGH CONGEALS ACROSS THE GREAT LAKES...AND UPPER RIDGE BUILDS
THROUGH THE ROCKIES AND EVENTUALLY NUDGES EASTWARD INTO THE NORTHERN
PLAINS. WILL BE DEALING WITH RESIDUAL COOLER POOL OF AIR IN MID
LEVELS ON MONDAY...FOR NOW HAVE LEFT THINGS WITH JUST A SLIGHT
INCREASE IN CLOUDS...BUT WILL NEED TO REVISIT IDEA OF PERHAPS
AN ISOLATED POP UP SHOWER.

GFS CONTINUES TO INDICATED A DEEPER TROUGH THROUGH THE GREAT
LAKES WHICH ACTS TO PULL A BACKDOOR FRONTAL ZONE ACROSS THE AREA ON
TUESDAY NIGHT...WHILE ECMWF IS ALMOST A DAY LATER AND MUCH WEAKER
WITH PUSH AS WELL AS HAVING A SLIGHTLY STRONGER EASTWARD PUSH TO
RIDGE LATE IN THE WEEK. DAY TO DAY LOWER LEVEL THERMAL PROGS ARE AS
MUCH AS 4-6C DIFFERENT...EC BEING COOLER TUESDAY...AND GFS COOLER
WEDNESDAY. AGAIN...THE RECENT WETNESS WOULD SUGGEST STAYING AWAY
FROM THE WARMEST SOLUTIONS...AND GENERALLY DID NOT ALTER TEMPS MUCH
FROM INITIAL GUIDANCE WHICH FELL INTO THE MIDDLE OF THE POTENTIAL
RANGE EACH DAY. END OF THE WEEK COULD SEE TEMPS PUSHING TOWARD 80
DEGREES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1201 PM CDT FRI APR 29 2016

MVFR STRATUS WILL REMAIN ACROSS MUCH OF THE AREA THROUGH THE TAF
PERIOD...THOUGH KHON MAY SCATTER OUT THROUGH THE AFTERNOON AND
EVENING. RAIN WILL BEGIN TO LIFT FROM THE SOUTH LATER
TONIGHT...AFFECTING KSUX AFTER 06Z AND KFSD BY MID MORNING ON
SATURDAY.

&&

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

$$

SHORT TERM...MJ
LONG TERM...CHAPMAN
AVIATION...JM



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