Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KFSD 272005
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
305 PM CDT MON JUL 27 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 304 PM CDT MON JUL 27 2015

ELIMINATED ALL POPS FOR THE REMAINDER OF THIS AFTERNOON AS IT LOOKS
LIKE THE ATMOSPHERE HAS STABILIZED BEHIND THIS MORNINGS AND EARLY
AFTERNOONS RAINFALL...SIMILAR TO WHAT HAPPENED LAST SATURDAY. THE
ONLY EXCEPTION IS ISOLATED POPS ARE WARRANTED IN THE LATE AFTERNOON
IN OUR SOUTH CENTRAL SD ZONES ONCE AGAIN AS THEY CONTINUE TO HEAT UP
REACHING THEIR CONVECTIVE TEMPERATURE. IN FACT SOME CUMULUS IS
FORMING RIGHT NOW IN THAT AREA. THE MAIN STORY FOR THE REST OF
TONIGHT IS OUR WELL ADVERTISED UPPER TROUGH MOVING INTO EASTERN MT
AND EASTERN WY...WITH A PRECEDING SHORT WAVE LIFTING ACROSS THE
NORTHERN PLAINS. BEHIND THE SHORT WAVE PASSAGE AND AHEAD OF THE
UPPER TROUGH...700MB TEMPERATURES INCREASE TO +14C WEST OF
INTERSTATE 29 WHICH SHOULD PUT AN ABRUPT END TO THE CONVECTION AS IT
PASSES THROUGH. STILL LIKE THE WAY THE ECMWF IS HANDLING THE
CONVECTIVE PATTERN THE BEST...DEVELOPING SOME SCATTERED ACTIVITY
LATER THIS EVENING IN OUR WESTERN ZONES...THEN LIFTING IT
NORTHEASTWARD OVERNIGHT GIVING LIKELY POPS MAINLY FOR SOUTHWEST MN
AND IMMEDIATE ADJACENT AREAS JUST AHEAD OF THE CAPPING. THE LOW
LEVEL JET INCREASES TO A STOUT 40 KNOTS IN OUR FORECAST AREA TONIGHT
WITH LIGHTER MID LEVEL WINDS AVERAGING 30 KNOTS. THE DIRECTIONAL
WIND SHEER VEERING WITH HEIGHT IS IMPRESSIVE BUT THE SPEED SHEAR IS
A BIT INVERSED FROM LOWER HEIGHTS TO MIDDLE HEIGHTS. THIS WOULD
SUGGEST ROTATING UPDRAFTS IN DISCREET CELLS ENOUGH TO SUPPORT LARGE
HAIL MAINLY IN OUR WESTERN AND PARTS OF OUR NORTHERN ZONES LATE
THIS EVENING. BUT AS THE SYSTEM MORPHS INTO A SMALL MCS...THE THREAT
COULD TRANSPOSE INTO AN ISOLATED WIND DAMAGE EVENT IN SOUTHWEST MN A
BIT LATER TONIGHT. WITH THE MID LEVEL TEMPERATURES SO VERY WARM ON
THE HEELS OF THE SHORT WAVE AND INCREASING IN TEMPERATURE AS SAID
ABOVE...NOT REALLY EXPECTING A WIDESPREAD SEVERE OUTBREAK. WOULD BE
MORE WORRIED IF MID LEVEL TEMPERATURES WERE FALLING.

THIS CONVECTION WILL DEPART THE FORECAST AREA LATE TONIGHT AND VERY
EARLY TUESDAY. BUT THERE COULD BE SOME ISOLATED REDEVELOPMENT ALONG
A SUBTLE WIND SHIFT IN OUR FAR SOUTHEAST ZONES TUESDAY AFTERNOON AS
THIS WIND SHIFT PRESSES EASTWARD. SHOULD BE A STRONG DRY LINE WITH
IT ALSO. IN THE LATE AFTERNOON...COULD BE A VERY BRIEF MARGINAL RISK
OF SEVERE WEATHER AROUND STORM LAKE BEFORE EXITING. OTHERWISE
LOOKING AT A WARM AND HUMID NIGHT TONIGHT...FOLLOWED BY COOLER
TEMPERATURES ON TUESDAY WITH MUCH DRIER AIR WORKING ITS WAY FROM
WEST TO EAST AS THE PROGRESSES. BUT AHEAD OF THE WEAK WIND
SHIFT...IT WILL REMAIN RATHER HUMID FROM WINDOM TO STORM LAKE ALL
DAY.


.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 304 PM CDT MON JUL 27 2015

THE POTENT CLOSED LOW WILL CONTINUE TO SLOWLY TREK EASTWARD THROUGH
SOUTH CENTRAL CANADA TUESDAY NIGHT AND WEDNESDAY. UPPER FLOW TURNS
NORTHWESTERLY AND A COOLER AIRMASS DESCENDS ACROSS THE NORTHERN
PLAINS IN ITS WAKE. COOLER AND DRY CONDITIONS ARE EXPECTED...HOWEVER
SOMEWHAT BREEZY WESTERLY LOW LEVEL WINDS ON TUESDAY NIGHT TURN
NORTHWESTERLY AND INCREASE ON WEDNESDAY. WHILE IT DOES NOT QUITE
LOOK TO BE ADVISORY LEVEL...SUSTAINED WINDS AROUND 15 TO 25 MPH WITH
GUSTS TO 35 MPH SEEM REASONABLE. ABUNDANT SUNSHINE IN A WELL MIXED
ENVIRONMENT WILL LEAD TO RELATIVELY LOW HUMIDITY AND MILD
TEMPERATURES IN THE LOW TO MID 80S WEDNESDAY.

MID LEVEL TEMPERATURES REBOUND ON THURSDAY AS UPPER LEVEL HEIGHTS
BUILD TO OUR WEST. WHILE WINDS WILL BE LIGHTER THAN WEDNESDAY...
MIXING DOWN SOME MILDER TEMPERATURES WILL IMPROVE HIGHS OUR WEST
WHERE THE LOW 90S WILL AGAIN BE POSSIBLE WEST OF THE JAMES RIVER.

WITHOUT THE UPPER RIDGE MAKING MUCH PROGRESS EAST HOWEVER...THE
GENERAL WEST NORTHWEST UPPER FLOW PATTERN HOLDS ON THROUGH THE
REMAINDER OF THE WEEK INTO EARLY NEXT WEEK. MOISTURE RETURN LOOKS
FAIRLY MINIMAL DURING THE PERIOD...THEREFORE IT LOOKS LIKE ANY WEAK
WAVES THAT DO DROP INTO THE NORTHERN PLAINS WILL NOT AMOUNT TO MUCH.
WENT AHEAD AND REMOVED SPOTTY SLIGHT CHANCE POPS FROM THE SUPERBLEND
THROUGH FRIDAY NIGHT. THERE IS A LITTLE BETTER AGREEMENT IN A WAVE
ARRIVING SATURDAY...BUT EVEN THIS POTENTIAL IS POOR WITH THE BETTER
CONVERGENCE EXPECTED NORTHEAST OF THE FORECAST AREA. ECMWF LIFTS
ANOTHER THERMAL BOUNDARY INTO THE AREA SUNDAY NIGHT WHILE THE GFS IS
FURTHER SOUTH. TEMPERATURES WILL BE NEAR SEASONAL...A LITTLE WARMER
LATE WEEK AND COOLING EARLY NEXT WEEK.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1215 PM CDT MON JUL 27 2015

VERY ABUNDANT LOW LEVEL MOISTURE IS STILL PRODUCING SOME IFR TO
MVFR CEILINGS...CURRENTLY MOST PREVALENT OVER SOUTHWEST MN AND
ACROSS THE LOWER JAMES RIVER VALLEY IN THE YANKTON AREA. WOULD NOT
RULE OUT SOME MVFR BROKEN CEILINGS NOW AND THEN THIS AFTERNOON...
ESPECIALLY AT THE KFSD AND KSUX TAF SITES. BUT FOR NOW...JUST
HEDGED TOWARD A SCATTERED DECK AS THE MVFR CONDITIONS ARE FAIRLY
SKITTISH. WILL UPDATE IF NEEDED. OTHERWISE ALSO THIS AFTERNOON...
A COUPLE OF THE HIRES MODELS INCLUDING THE NMM AND ARW ARE
PRODUCING A LOT OF CONVECTION IN THE KFSD AND KSUX AREAS EARLY
THIS AFTERNOON. BUT THEY ALSO HAVE CONVECTION RIGHT NOW WHICH IS
NOT PANNING OUT...SO DID NOT INCLUDE ANY TSRA IN THE NEAR TERM FOR
KFSD AND KSUX YET. AGAIN...WILL UPDATE IF TSRA BEGINS TO DEVELOP.

TONIGHT A VIGOROUS UPPER TROUGH WILL MOVE THROUGH THE NORTHERN AND
CENTRAL PLAINS...WITH THE STRONGEST PART OF THE WAVE REMAINING TO
THE NORTH OF FORECAST AREA. STILL...WOULD NOT RULE OUT TSRA
CHANCES FIRST AT KHON LATE THIS EVENING AND OVERNIGHT...POSSIBLY
DEVELOPING SOUTHWARD INTO KFSD AND KSUX LATE TONIGHT. THERE IS
ENOUGH OF A CHANCE TO WARRANT A TEMPO GROUP FOR THE THREE TAF
SITES AT THIS TIME. A SURFACE WIND SHIFT WILL THEN FOLLOW THE
WAVE TUESDAY MORNING. THERE ARE SOME HINTS AT SOME MVFR STRATO
CUMULUS DEVELOPMENT ALONG AND BEHIND THE WIND SHIFT ESPECIALLY AT
KFSD.


&&

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

$$

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


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.