Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 052330
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
630 PM CDT TUE MAY 5 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 358 PM CDT TUE MAY 5 2015

SUBTLE WARM FRONT CREEPING NORTHWARD ACROSS THE AREA.  WITH THE GULF
WIDE OPEN SEEING GOOD MOISTURE RETURN IN QUITE SOME TIME.  PWAT
VALUES CLIMBING TO OVER AN INCH ACROSS THE AREA...OR 90 PERCENT OF
THE MOVING AVERAGE.  MOIST ADIABATIC LAPSE RATES FROM THE SURFACE
TO 200 MB...SO AS THE MOISTURE CONTINUES TO INCREASE...WILL LIKELY
SEE SCATTERED SHOWERS DEVELOP ACROSS THE AREA. NOT A LOT TO GRASP ON
IN TERMS OF FORCING...BUT HAVE FOCUSED POPS ESPECIALLY ALONG AND
WEST OF THE JAMES RIVER VALLEY AS THE UPPER WAVE LIFTS TO THE
NORTHEAST.  WITH DIURNAL HEATING...SHOULD SEE GREATER INSTABILITY
THROUGH THE AFTERNOON HOURS. THEREFORE...HAVE SHOWERS WITH ISOLATED
THUNDER THROUGH THE NIGHT AND MORE BONAFIDE THUNDERSTORMS TOMORROW
AFTERNOON.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 358 PM CDT TUE MAY 5 2015

UPPER TROUGH SWINGS NORTHEAST THROUGH THE REGION WEDNESDAY NIGHT...
WITH GFS/GEM/ECMWF IN GOOD AGREEMENT SHOWING BAND OF SHOWERS AND
THUNDERSTORMS PROGRESS EAST ACROSS THE FORECAST...WITH WESTERN AREAS
DRYING OUT AS WINDS SHIFT TO THE SOUTHWEST AND WEST BEHIND THE
SURFACE FRONT. DEEP MOISTURE SHOULD SUPPORT FAIRLY EFFICIENT
RAINFALL WITH THE WEDNESDAY NIGHT ACTIVITY...WITH THIS PERIOD
SHOWING THE BEST POTENTIAL FOR RAINFALL AMOUNTS OF A HALF INCH OR
MORE IN SOME LOCATIONS.

STILL UNSETTLED WITH A CHANCE OF SCATTERED SHOWERS/THUNDERSTORMS
INTO THURSDAY AS A SECONDARY WAVE AND COLD FRONT SLIDE THROUGH THE
AREA...THEN LOOKS LIKE A DRIER PERIOD ON TRACK FOR FRIDAY/SATURDAY
AS WEAK UPPER RIDGE MOVES ACROSS THE REGION. THESE DAYS LOOK TO BE A
LITTLE COOLER THAN RECENT DAYS...BUT STILL SEASONABLY MILD WITH
HIGHS MOSTLY IN THE 60S THURSDAY THROUGH SATURDAY.

ANOTHER LARGE TROUGH DEVELOPS ACROSS THE ROCKIES THROUGH THE FIRST
PART OF THE WEEKEND...AND IS THEN PROGGED TO SHIFT INTO THE PLAINS
SATURDAY NIGHT THROUGH MONDAY. WHILE THERE ARE MODEL DIFFERENCES IN
THE TIMING/STRENGTH OF THE OF THE TROUGH...GENERALLY SEEING STRONG
AGREEMENT IN INCREASED PRECIP CHANCES SPREADING OVER THE AREA FOR
SATURDAY NIGHT/SUNDAY...THEN GRADUALLY DIMINISHING THROUGH SUNDAY
NIGHT/MONDAY. POTENTIAL RAIN WILL KEEP TEMPERATURES ON THE COOLER
SIDE TO START THE WEEK...WITH SOME AREAS LIKELY STRUGGLING TO REACH
LOWER-MID 50S FOR HIGHS SUNDAY AND/OR MONDAY. LOOKS LIKE POTENTIAL
FOR MORE MUCH NEEDED RAINFALL...BUT AT THIS TIME THE SEVERE THREAT
APPEARS LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 627 PM CDT TUE MAY 5 2015

SCATTERED RAIN SHOWERS WITH ISOLATED THUNDER WILL PERSIST THROUGH
AROUND MID EVENING...WITH A BETTER CHANCE OF SHOWERS AND STORMS
BUILDING INTO THE REGION AFTER 09Z TONIGHT. EXPECT GENERALLY VFR
CONDITIONS THROUGH 09Z...WITH MVFR CEILINGS DEVELOPING WITH THE
APPROACHING UPPER LOW AND INCREASING PRECIPITATION CHANCES. RAIN
BECOMES LIKELY LATE IN THE TAF PERIOD.

&&

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

$$

SHORT TERM...
LONG TERM...JH
AVIATION...


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