Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 030857
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
357 AM CDT TUE MAY 3 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT TUE MAY 3 2016

MAIN CHALLENGE TODAY ARE HIGH TEMPERATURES. THE FORECAST AREA IS IN
POSITION FOR A GOOD SOLID WARMUP TODAY WITH A WEST TO NORTHWEST WIND
DOMINATING BEFORE A COLD FRONTAL PASSAGE LATE THIS AFTERNOON AND
EVENING. SO A GOOD MIXING DAY IS IN STORE. MIXING TEMPERATURES JUST
FROM 850MB YIELDS HIGHS OF 70 TO 75 DEGREES. MANY OF THE CONSENSUS
GUIDANCE VALUES LOOK TOO COOL...WITH THE MAV GUIDANCE LOOKING THE
BEST...ESPECIALLY CONSIDERING MONDAYS HIGHS HAD NO TROUBLE MIXING TO
THE 850-800MB LAYER. THE ONE CHALLENGE TO THIS THINKING IS THE
CIRRUS. IF IT GETS THICK ENOUGH...IT COULD HOLD TEMPERATURES DOWN A
CATEGORY CLOSER TO WHAT CONSENSUS GUIDANCE READINGS ARE SHOWING.

THIS EVENING...WELL ADVERTISED SHORT WAVE ENERGY WILL DIVE STRAIGHT
SOUTHWARD ACROSS MN AND IA...WITH AN ATTENDANT SURFACE COLD FRONT.
THERE IS ENOUGH MOISTURE AROUND THE 800-750MB LAYER TO CONTINUE TO
WARRANT A SMALL POP FOR SHOWERS EAST OF I 29 THIS EVENING. AFTER THE
WAVE PASSAGE...SKIES WILL CLEAR...WINDS WILL DECREASE...AND LOW
TEMPERATURES SHOULD BE IN THE LOWER 40S.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 356 AM CDT TUE MAY 3 2016

AS EXPECTED...LIFE UNDER THE RIDGE PORTION OF THE OMEGA
BLOCK ON THURSDAY AND FRIDAY HAS BEEN TRENDING WARMER AND WARMER
EACH DAY. SOUTHERLY FLOW WILL BEGIN TO KICK IN ON THURSDAY WITH
LOADS OF SUNSHINE...WITH MIXING TAKING TEMPS TO THE MID 70S IN SW MN
AND NW IA...AND TO NEAR 80 IN SOUTH CENTRAL SD. NOT A GREAT PUSH OF
LOW LEVEL MOISTURE TO HOLD TEMPS UP AS SOUTHERLY FLOW RELAXES A BIT
FOR LOWER ELEVATION LOCATIONS THURSDAY NIGHT...BUT SHOULD SEE MAINLY
LOWER TO MID 50S. ON FRIDAY...EVEN WARMER TEMPS ARE LIKELY AS UPPER
RIDGE FOLDS OVER A BIT AS UPPER WAVE BEGINS TO KNOCK AT THE CANADIAN
BORDER NEAR THE GREAT LAKES.  FRONTAL BOUNDARY STARTS TO PUSH
SOUTHWARD...AND WHILE IT DOES REMAIN NORTH OF THE CWA THROUGH THE
DAY...FLOW AT LOWER LEVELS WILL SLIP IN A BIT MORE WESTERLY
COMPONENT. AT FACE VALUE...00Z GFS WOULD THREATEN UPPER 80S ON
FAIRLY SHALLOW MIXING TO 925 HPA...BUT IS THE WARMEST OF ALL
SOLUTIONS. CONSIDERING THE MOIST GROUND STATE...AND BULK OF
SOLUTIONS JUST A SHADE COOLER...WILL KEEP FROM GOING TOO EXTREME...
BUT WILL RAISE INITIALIZATION GUIDANCE BY A SOLID 3-6 DEGREES.

TRENDS OVER THE LAST DAY HAVE BEEN FOR THE WAVE TO DIG MORE
FORCEFULLY INTO THE GREAT LAKES...AND AS A RESULT GIVE LOW LEVEL
FRONTAL BOUNDARY A GOOD SHOVE SOUTHWARD SATURDAY INTO SUNDAY... ALL
THE WAY TO I-70 BY SATURDAY EVENING. THERE WILL BE A CHANCE FOR A
FEW SHOWERS AND THUNDERSTORMS NEAR AND POST FRONTAL AS TAIL OF WAVE
SLIPS PAST MAINLY LATER FRIDAY NIGHT INTO SATURDAY. DRIER AIR WILL
RAPIDLY SPREAD SOUTHWARD SATURDAY AND SATURDAY NIGHT...LIKELY
SHUTTING OFF MOST OF THE PRECIPITATION...IF NOT ALL..WELL INTO
SUNDAY.  NOT EXACTLY A STRONG COLD INTRUSION BEHIND BOUNDARY ON
SATURDAY... AND AFTER CLOUDS SHIFT SOUTHWARD ALONG WITH MINIMAL
PRECIPITATION CHANCE...SHOULD MAINTAIN 60S TO LOWER 70S...WARMEST
ACROSS THE DRIER NORTH ON SUNDAY.

EVENTUALLY...THE WESTERN CLOSED LOW FORMERLY OF THE SHORT LIVED
OMEGA BLOCK...WILL BEGIN TO LIFT OUT OF THE ROCKIES AND SLOWLY SHEAR
TOWARD THE AREA STARTING MONDAY. PRECIPITATION CHANCES ARE EXPECTED
TO INCREASE WITH THIS FEATURE. CONFIDENCE ON TIMING IS FAIRLY LOW
GIVEN DISPARITY ON THE SPEED OF SYSTEM...BUT WITH MAIN INSTABILITY
GRADIENT WELL TO THE SOUTH AND THE FAIRLY WEAK MID LEVEL WINDS...
SEVERE THREAT WOULD SEEM TO BE QUITE LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1038 PM CDT MON MAY 2 2016

VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. NORTHWESTERLY
WINDS WILL PICK UP ON TUESDAY AFTERNOON...GUSTING TO AROUND 20 KTS
AT TIMES.

&&

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

$$

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



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