Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 302045
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
345 PM CDT TUE JUN 30 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 344 PM CDT TUE JUN 30 2015

FAIRLY COMPLICATED FORECAST IN THE NEAR TERM. SYNOPTICALLY...UPPER
FLOW CONTINUES TO BE STRONGLY DEVIATED FROM THE NORTHWEST...WITH
MASSIVE RIDGING OVER THE SOUTHWEST UNITED STATES AND STRONG
TROUGHING FROM THE MS VALLEY EASTWARD. AT THE SURFACE...THERE IS
REALLY NOT A LOT GOING ON WITH LIGHT FLOW EXPECTED TO CONTINUE. WITH
A BROAD NORTHWEST FLOW CONTINUING IN THE MID LEVELS...CONCERNED THAT
THE SMOKE IMPACTS WILL CONTINUE FROM CENTRAL CANADA AT LEAST THROUGH
TONIGHT...AND POSSIBLY EVEN INTO WEDNESDAY. THAT SAID...MID LEVEL
MOISTURE IS IN NO SHORT SUPPLY AS A FRONTAL BOUNDARY IN THE 850-
700MB LAYER REMAINS RATHER ENTRENCHED COUPLED WITH ISENTROPIC LIFT
IN THAT LAYER. THEREFORE THE SHOWERS HAVE CONTINUED THROUGH TODAY
AND THEIR MOVEMENT EASTWARD IS NOW BEGINNING AS EXPECTED LATE THIS
AFTERNOON AND EVENING WHICH WILL IMPACT MORE OF OUR EASTERN ZONES.
THERE IS A SHORTWAVE WHICH CURRENTLY EXTENDS FROM CENTRAL ND TO
NORTH CENTRAL SD. THIS WAVE WILL DIVE SOUTHEAST THROUGH THE EVENING
HOURS WITH THE HIRES MODELS PRIMARILY AFFECTING AREAS ALONG AND WEST
OF A SIOUX CITY...TO SIOUX FALLS AND HURON LINE. OVERNIGHT AND LATE
TONIGHT...THE BEST RAIN CHANCES WILL BE LINGERING AROUND SIOUX CITY
AND STORM LAKE AS THE WAVE EXITS. SO THE AFOREMENTIONED AREAS HAVE
HIGH CHANCE TO LIKELY POPS. NOT REAL CONCERNED ABOUT ANY SEVERE
WEATHER OR MARGINAL SEVERE WEATHER CONDITIONS AT THIS TIME. THIS IS
BECAUSE THE EXISTING RAINFALL HAS REALLY STABILIZED CONDITIONS
COUPLED WITH A HIGH DEGREE OF MID AND HIGH CLOUDS...AND SMOKE...
KEEPING TEMPERATURES FAIRLY COOL.

ON WEDNESDAY...IT APPEARS THE 850-700MB FOCUS SHIFTS INTO OUR
EASTERN ZONES IN THE MORNING. BUT SKITTISH CHANCES OF RAINFALL WILL
CONTINUE ALMOST ANYWHERE DUE TO THE LINGERING ISENTROPIC LIFT.
CONCERNING TEMPERATURES...LOWS TONIGHT WILL ONCE AGAIN BE GENERALLY
60 TO 65 DEGREES...FOLLOWED BY HIGHS ON WEDNESDAY IN THE 70S. 80S
WILL ONCE AGAIN RETURN THOUGH TO OUR FAR SOUTHWEST ZONES.


.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 344 PM CDT TUE JUN 30 2015

MUCH OF THE REMAINDER OF THE WEEK THE NORTHERN PLAINS REMAINS IN
NORTHWEST FLOW AS UPPER LEVEL TROUGH CONTINUES TO SPIN ACROSS THE
EASTERN CANADA INTO THE NORTHEASTERN CORNER OF THE US. WEDNESDAY
NIGHT THROUGH SATURDAY THERE ARE PERIODIC SHIRT WAVES THAT MOVE
THROUGH THE AREA.  WITH WEAK INSTABILITY ACROSS THE AREA...COULD SEE
A FEW PASSING SHOWERS AND STORMS ACROSS THE REGION.  INSTABILITY AND
SHEAR DO NOT LOOK TO BE STRONG ENOUGH TO SUPPORT SEVERE WEATHER.

TOUGH CALL ON STORM POTENTIAL ON 4TH OF JULY AS AN ELONGATED
WEAKENING SHORTWAVE SLIDES EAST ACROSS THE FORECAST AREA.  MODELS
OFFERING A VARIETY OF SOLUTIONS WITH THIS FEATURE...ANYTHING FROM
DRY TO HIGH POPS.  FOR NOW...OPTED FOR JUST SOME SLIGHT CHANCE POPS
DURING THE DAY. 20-25 KNOT LOW LEVEL JET DEVELOPS SATURDAY NIGHT
AHEAD OF AN APPROACHING LOW SITUATED FURTHER TO THE NORTH AND WEST.
 MASS CONVERGENCE COULD BE ENOUGH TO TRIGGER SOME
STORMS...ESPECIALLY ACROSS THE NORTHERN HALF OF THE FORECAST AREA.

BEST CHANCE OF THUNDERSTORMS WILL BE SUNDAY NIGHT AS A COLD FRONT
WORKS THROUGH THE FORECAST AREA.  WITH THE PASSAGE OF THE
FRONT...CAPE INCREASES TO NEAR 2000 J/KG AND EFFECTIVE BULK SHEAR
SPIKES TO 50-55 KNOTS.  HAVE CONTINUES TO INCREASE POPS...AND WILL
CONTINUE TO HIGHLIGHT STRONG TO SEVERE STORMS SUNDAY NIGHT IN THE
HWO.

DRIER YET SEASONABLE CONDITIONS ARE EXPECTED TO BEGIN THE WEEK NEXT
WEEK. BEHIND THE COLD FRONT ON MONDAY...COULD SEE SMOKE RETURN TO
THE REGION WITH NORTHWEST FLOW DRAWING AIR DOWN DIRECTLY FROM
CENTRAL AND NORTHERN ALBERTA.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1227 PM CDT TUE JUN 30 2015

AFTER PERUSING OVER THE LATEST 12Z NAM AND GFS SOUNDINGS AND
HUMIDITY TIME SECTIONS...CURRENT THOUGHTS ARE THAT THE CEILINGS
WILL LIKELY REMAIN VFR THROUGH THE TAF PERIOD. THE VISIBILITY IS A
LITTLE MORE PROBLEMATIC DUE TO ONGOING SMOKE CONCERNS...AND THERE
WILL LIKELY BE TIMES OF MVFR DUE TO SMOKE. IN ADDITION THERE WILL
BE CHANCES FOR SHOWERS OFF AND ON TONIGHT AND POSSIBLY INTO
WEDNESDAY MORNING. BUT MOST CONCERNING IS THERE STILL COULD BE
SOME TSRA IN THE SIOUX CITY VICINITY THIS EVENING.


&&

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

$$

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



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