Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 142040
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
340 PM CDT SUN SEP 14 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 338 PM CDT SUN SEP 14 2014

WATER VAPOR IMAGE SHOWING A SHORTWAVE DROPPING THROUGH
NORTHERN/EASTERN MONTANA LATE THIS AFTERNOON AND THIS FEATURE WILL
DROP INTO EASTERN SOUTH DAKOTA BY EARLY MONDAY MORNING. THIS WILL
BRING INCREASING CHANCES OF SHOWERS TO MUCH OF THE CWA LATER THIS
EVENING WITH STRENGTHENING LOW/MID LEVEL FRONTOGENESIS DEVELOPING
ACROSS THE REGION. MODELS HAVE TRENDED A LITTLE FARTHER NORTH WITH
THE HIGHER QPF...CLOSER TO THE UPPER LEVEL SUPPORT...SO FOLLOWED
SUIT WITH THE POPS...WITH MODERATE TO LIKELY POPS AS FAR NORTH AS
THE EASTERN HIGHWAY 14 CORRIDOR LATE TONIGHT. CURRENT RADAR SHOWING
ECHOES THROUGH THE WESTERN AND CENTRAL HIGHWAY 14 CORRIDOR...THOUGH
THINK LITTLE OF THIS IS REACHING THE GROUND WITH CLOUD BASES RUNNING
AROUND 9 TO 11 KFT. DID INTRODUCE SPRINKLES OVER THIS AREA HOWEVER
THROUGH THE REMAINDER OF THE AFTERNOON...BEFORE LEGITIMATE RAIN
CHANCES KICK IN DURING THE EVENING WITH INCREASING FORCING/BETTER
SATURATION. BY LATE TONIGHT...AS THE SHORTWAVE BEGINS TO PULL OFF TO
THE EAST AND FRONTAL FORCING SAGS SOUTHWARD...WILL HAVE DECREASING
CLOUDS IN OUR NORTH AND WEST...AND WITH LIGHT WINDS TEMPERATURES
WILL DROP INTO THE LOWER 40S OVER THIS AREA. TO THE SOUTHEAST WHERE
CLOUDS WILL REMAIN...LOOKING AT LOWS IN THE UPPER 40S OVER THE LOWER
MISSOURI RIVER CORRIDOR INTO NORTHWEST IOWA.

OTHER THAN SOME LINGERING SHOWERS THROUGH FAR SOUTHEASTERN IOWA
DURING THE MORNING...THE REMAINDER OF MONDAY WILL HAVE IMPROVING
CONDITIONS AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. WITH
SKIES BECOMING MOSTLY SUNNY...HIGHS WILL MAKE IT INTO THE LOWER TO
MID 60S.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 338 PM CDT SUN SEP 14 2014

LARGE...COOL HIGH PRESSURE MOVES EASTWARD ACROSS THE CENTRAL PLAINS
WHICH GIVES THE FORECAST AREA A SOUTHERLY RETURN FLOW OF AIR MONDAY
NIGHT. SKIES LOOK CLEAR. THE SOUTHERLY WINDS SHOULD HELP KEEP OUR
WESTERN ZONES SOMEWHAT MILD MONDAY NIGHT...WITH LOWS STAYING IN THE
MID 40S OVER THOSE LOCATIONS. BUT AS IS OFTEN THE CASE...LIGHTER
WINDS AND A COOLER AIR MASS WILL LIKELY PUT OUR FAR EASTERN ZONES
AROUND WINDOM MN AND SPENCER IA IN THE UPPER 30S TO NEAR 40 DEGREES.
TUESDAY WILL FOLLOW WITH A SUNNY DAY AND MILD HIGHS IN THE UPPER 60S
TO MID 70S. AREAS WEST OF I 29 MAY BE A BIT BREEZY AS THE SOUTHERLY
FLOW CONTINUES.

LATE TUESDAY NIGHT IS INTERESTING IN THAT A WEAK SHORT WAVE MOVES
SOUTHEASTWARD ACROSS THE FORECAST AREA. AS THE LOW LEVEL FLOW BACKS
TO THE SOUTHEAST...MOISTURE IS DRAWN UP WITH THE SHORT WAVE AND IS
QUITE STRONG NEAR 850-800MB EAST OF THE JAMES RIVER VALLEY BY AFTER
MIDNIGHT TUESDAY NIGHT. THIS MOISTURE FETCH LASTS INTO WEDNESDAY
MORNING ALONG AND EAST OF I 29. THETAE ADVECTION IS ALSO STRONG
NOSING UP THE I 29 CORRIDOR LATE TUESDAY NIGHT. THEREFORE DECIDED TO
OPT FOR A SLIGHT CHANCE POP FOR SOME OF OUR SOUTHERN ZONES...BUT
KEPT IT OUT OF EARLY WEDNESDAY MORNING FOR NOW. THERE IS UNCERTAINTY
IF LIGHT CONVECTION INDEED UNFOLDS...HOW IT WILL TRACK INTO
WEDNESDAY AND WHAT AREAS IT WILL AFFECT. HIGHS ON WEDNESDAY WILL
CONTINUE TO BE MILD WITH TEMPERATURES RANGING FROM THE UPPER 60S
AROUND STORM LAKE AND SPENCER IA...TO THE UPPER 70S IN OUR CENTRAL
SD ZONES.

FURTHER OUT...THE HUMIDITY BEGINS TO INCREASE LATE IN THE WEEK BY
THURSDAY...AND ESPECIALLY ON FRIDAY AS DEW POINT TEMPERATURES RETURN
INTO THE 60S. THURSDAY STILL LOOKS BREEZY ESPECIALLY WEST OF
INTERSTATE 29...WITH MILD TEMPERATURES IN THE 70S ACROSS THE
FORECAST AREA. FRIDAY LOOKS LIKE THE WARMEST DAY OF THE WEEK AHEAD
OF A COLD FRONT...WITH HIGHS IN THE MID 70S TO LOWER 80S. CHANCES
FOR RAIN IN THE EXTENDED LOOK SKITTISH UNTIL POSSIBLY FRIDAY NIGHT
WHEN THE WIND SHIFT/COLD FRONT MOVES THROUGH. POPS WERE GIVEN IN THE
ALL BLEND EVERYWHERE IN OUR AREA FOR FRIDAY DAY PERIOD AND SATURDAY
NIGHT. BUT BACKED THOSE CHANCES OFF JUST TO OUR EASTERN ZONES. THE
DETERMINISTIC GFS AND ECMWF WERE REALLY NOT THAT FAR APART SO WERE
BLENDED FOR THE BASIS OF THE EXTENDED FORECAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1205 PM CDT SUN SEP 14 2014

VFR CONDITIONS EXPECTED THROUGH EARLY EVENING...THEN SCATTERED
RAIN SHOWERS WILL DEVELOP ACROSS THE AREA DURING THE OVERNIGHT
HOURS...WITH AREAS OF MVFR CIGS/VISBYS IN RAIN. CONDITIONS WILL
RETURN TO VFR BY MONDAY MORNING.

&&

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

$$

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



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