Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 262007
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
307 PM CDT WED AUG 26 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 306 PM CDT WED AUG 26 2015

CLOUDS ASSOCIATED WITH ELEVATED ACTIVITY SLIDING TO THE SOUTH AND
EAST OF THE FORECAST AREA WITH ANOTHER BATCH OF CLOUD MOVING INTO
THE REGION FROM THE WEST. GULF IS WIDE OPEN AND WITH LOW LEVEL JET
EXPECTED TO DEVELOP ACROSS THE PLAINS OVERNIGHT...COULD SEE SOME
ELEVATED SHOWER AND THUNDERSTORMS DEVELOP THROUGH THE OVERNIGHT AS
WARM CONVEYOR CONTINUES TO DRAW INCREASING MOISTURE INTO THE REGION.
 PWAT VALUES ARE EXPECTED TO CLIMB TOWARDS 1.5 INCHES BY 12Z
THURSDAY MORNING...AND THEN INCREASE TO NEAR TWO INCHES BY THURSDAY
EVENING AHEAD OF A STRONG SHORTWAVE COMING IN.  CERTAINLY SOME WEAK
ELEVATED INSTABILITY LINGERING THROUGH THE OVERNIGHT INTO
THURSDAY...BUT GREATEST FOCUS APPEARS TO BE LATE TOMORROW AFTERNOON
INTO TOMORROW NIGHT AS CURRENTLY SHORT WAVE IN THE FOUR CORNERS
REGION APPROACHES FROM THE SOUTHWEST.  HAVE MADE LITTLE IN THE WAY
OF CHANGES IN TERMS OF TEMPS.  WILL BE A WARMER NIGHT TONIGHT WITH
INCREASING MOISTURE FLUX...AND TEMPERATURES WARMING INTO THE 70S
THROUGHOUT THE DAY TOMORROW.


.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 306 PM CDT WED AUG 26 2015

PRIMARY STORY IN THE FORECAST REMAINS CENTERED ON HEAVY RAIN
POTENTIAL THURSDAY EVENING INTO EARLY FRIDAY.  MODEL GUIDANCE
REMAINS A BIT JUMPY WITH THE CORRIDOR OF POTENTIAL HEAVY RAINS YET
AGAIN TODAY...LIKELY DUE TO THE DISJOINTED NATURE OF THE UPPER WAVE
AS IT ROTATES NORTHEAST INTO THE PLAINS LATER TONIGHT.  MOST
GUIDANCE CONTINUES TO MAINTAIN A SLIGHT SPLIT IN THE UPPER WAVE AS
IT LIFTS NORTHEAST TONIGHT...AND THEN REPHASING THE WAVE TOGETHER
THURSDAY NIGHT INTO FRIDAY AS IT CRESTS THE TOP OF THE MID-LVL RIDGE.

THAT SAID...VERY IMPRESSIVE MOISTURE TRANSPORT INTO THE AREA WILL
BRING PWAT VALUES APPROACHING THE 99TH PERCENTILE BY THURSDAY
NIGHT...WITH AN ACTIVE LLJ...NEARLY 2-3 SD ABOVE CLIMO...QUICKLY
DEVELOPING THURSDAY EVENING. GIVEN IMPRESSIVE UPPER LIFT...ABUNDANCE
OF MOISTURE...HEAVY RAIN LOOKS LIKE A GOOD BET. THE AXIS OF THIS
HEAVIER RAIN REMAINS IN DOUBT TO A DEGREE. AXIS OF MOISTURE
TRANSPORT OVERTOP H850 FRONT WOULD SUGGEST AREAS ALONG AND SOUTH OF
I-90 WOULD HAVE THE HIGHEST RISK FOR A FEW INCHES OF RAIN. ITS NOT
IMPOSSIBLE THAT THIS AXIS COULD SHIFT SLIGHTLY FURTHER NORTH...BUT
IT MAY TAKE UNTIL MID-DAY THURSDAY TO REALLY DETERMINE WHERE THE
HIGHEST CORRIDOR OF RAIN WOULD OCCUR.

SOUNDINGS WOULD SUGGEST MINIMAL AMOUNT OF THUNDER AS THIS RAIN MOVES
THROUGH...WITH AN ALMOST TROPICAL SOUNDING. 3 AND 6 HR FFG HAS
ALREADY CLIMBED INTO THE 2-3 INCH RANGE...WITH HEADWATER GUIDANCE
SUGGESTING MOST RIVERS WILL HOLD A FEW INCHES WITH MINIMAL IMPACT.
SO NOT ANTICIPATING THE NEED FOR A FLOOD WATCH ATTM...BUT LATER
SHIFTS WILL NEED TO CONTINUE TO MONITOR FORECAST TRENDS. FOR
NOW...WILL INCLUDE HEAVY RAIN WORDING IN GRIDS AND TRY TO HIGHLIGHT
THE POTENTIAL FOR HIGHER AMOUNTS IN OTHER FORECAST PRODUCTS.

THIS SYSTEM WILL WRAP UP AND SLIDE EAST FRIDAY MORNING...BUT CLOUD
COVER MAY LINGER THROUGH THE EAST EAST OF I-29.  WILL LOWER
TEMPERATURES AND IT IS POSSIBLE SOME AREAS MAY NOT REACH 70 DEGREES.

INTO THE WEEKEND AND EARLY NEXT WEEK...WARMING TEMPERATURES WILL BE
THE STORY AS MID-LVL RIDGING BUILDS.  TEMPERATURES WILL CLIMB BACK
TO AND ABOVE NORMAL IN THE 80S WITH DRY CONDITIONS EXPECTED INTO
EARLY NEXT WEEK.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1233 PM CDT WED AUG 26 2015

VFR CONDITIONS EXPECTED TO PREVAIL THROUGH 18Z THURSDAY. ISOLATED
CONVECTIVE ACTIVITY ALONG THE I-29 CORRIDOR IS EXPECTED TO
CONTINUE TO WANE THROUGH THE AFTERNOON HOURS. SOUTHEAST FLOW
SHOULD DECREASE AND BECOME MORE EASTERLY OVERNIGHT. COULD SEE SOME
ELEVATED SHOWERS/THUNDERSTORMS DEVELOP OVERNIGHT LIFTING NORTHEAST
THROUGH THE REGION. EXPECT STORMS TO BE ELEVATED ENOUGH TO RESULT
IN VFR CONDITIONS...BUT TIMING OF PRECIPITATION IS DIFFICULT SO
LEFT MENTION OUT AT THIS POINT.


&&

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

$$

SHORT TERM...
LONG TERM...DUX
AVIATION...



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