Hail and Damaging Wind in South Dakota, June 19, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1215 PM CDT FRI JUN 19 2015

.UPDATE...
ISSUED AT 1213 PM CDT FRI JUN 19 2015

MCS FROM OVERNIGHT HOURS HAS GREATLY DISSIPATED FROM EARLIER
OVERNIGHT STATUS. REPEATED ATTEMPTS FOR CLUSTERS OF THUNDERSTORMS
TO PUSH TO THE EAST OF THE JAMES VALLEY HAS MET WITH A STRONG
WEAKENING OR DISSIPATION WITH THE MUCH MORE STABLE CONDITIONS.
HRRR/RAP MODELS HAVE NOT DONE WELL IN SUGGESTING THIS DISSIPATION...
AND CONTINUE TO STRUGGLE WITH OVERPREDICTION OF CONVECTIVE THREAT
IN THE IMMEDIATE TERM. WILL CONTINUE WITH SOME SCATTERED TO LIKELY
LEVEL POPS IN THE NORTH FOR A COUPLE HOURS...BUT GRADUALLY SHOULD
SEE THREAT DIMINISH TO BARE MINIMUM ALONG MID LEVEL BOUNDARY IN
THE FAR NORTH. OTHERWISE...LARGE STRATUS FIELD ACROSS
CENTRAL/WESTERN NEBRASKA CONTINUES TO TAUNT THE FAR WESTERN CWA.
SHOULD CONTINUE TO UNDERGO DISSIPATION AS IT ADVECTS NORTH TO
NORTHEAST THROUGH THE AFTERNOON...BUT MAY HOLD CLOUDS IN FOR A
LONGER PERIOD...AND EVEN WITH DISSIPATION...LONG ENOUGH TO IMPACT
POTENTIAL HIGHS WEST OF THE JAMES...AND HAVE TRIMMED BACK HIGHS A
BIT FOR BOTH THIS AREA...AND THOSE LOCATIONS NEAR THE MORE
LINGERING PRECIPITATION THREAT INTO EARLY AFTERNOON.

OTHERWISE...FOCUS FOR THE SHORT TERM FORECAST CONTINUES TO BE THE
SEVERE CONVECTIVE THREAT TONIGHT. STRONG WAVE MOVING THROUGH
IDAHO WILL BE THE TRIGGER THIS EVENING FOR DEVELOPMENT OF MORE
SIGNIFICANT CONVECTIVE ACTIVITY ACROSS SOUTHEAST MONTANA/NORTHWEST
SOUTH DAKOTA...WHICH WILL PLOW TO THE EAST/SOUTHEAST OVERNIGHT.
0-3KM SHEAR HAS COME IN A BIT STRONGER IN THE PRE COMPLEX
ENVIRONMENT...AND LIKELY TO GET SOME ML/ELEVATED CAPE UP TO 1500
J/KG. EVOLUTION TO A LARGER SCALE BOW ECHO WOULD SEEM VERY
PLAUSIBLE...PRIMARILY WITH A THREAT FOR DAMAGING WINDS GUSTS 70 TO
80 MPH. SOME LARGE HAIL POTENTIAL WILL EXIST ACROSS THE WEST AND
SOUTHERN FLANKS WITH STRONG LOW LEVEL JET. RAPID MOVEMENT OF
SYSTEM ONCE EVOLVED WITH LIKELY LIMIT THE PRECIPITATION
AMOUNTS...BUT RATES WILL LIKELY BE QUITE HIGH FOR A BRIEF TIME...
WHICH WOULD INTRODUCE THREAT FOR MORE URBANIZED AND POOR DRAINAGE
AREAS TO EXPERIENCE SOME WATER ISSUES AS SYSTEM PUSHES THROUGH.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT FRI JUN 19 2015

COMPLICATED FORECAST FOR TODAY.  STRONG MCS CURRENTLY WORKING INTO
WESTERN PORTIONS OF THE STATE AS OF 08Z....AND IS EXPECTED TO
APPROACH THE WESTERN EDGE OF THE FORECAST AREA IN THE 13-14 Z TIME
FRAME.  WHAT IS INTERESTING...IS THAT THE AIR OVER THE FORECAST AREA
IS COMPLETELY STABLE...BUT OFTEN TIMES...STRONG...WELL ESTABLISHED
MCS CAN OUTRUN THE INSTABILITY.  HRRR HAS BEEN VERY CONSISTENT WITH
THIS...AND RAP IS NOW BEGINNING TO TREND IN THIS DIRECTION AS WELL.
HAVE BEGUN TO TREND UPWARDS WITH POPS IN NORTHWEST FORECAST AREA IN
CENTRAL SOUTH DAKOTA...BUT TRAIL POPS OFF TO THE EAST AS COMPLEX IS
EXPECTED TO FALL APART AS IT WORKS DEEPER INTO THE STABLE AIR.

RESIDUAL CLOUD COVER WILL REDUCE HEATING POTENTIAL FOR TODAY...AND
HAVE CUT BACK HIGH TEMPERATURES ACROSS THE AREA...WITH GREATEST
ADJUSTMENTS IN CENTRAL SOUTH DAKOTA.

LOW LEVEL CONVERGENCE INCREASES THIS EVENING AS 35-45 KNOT LOW LEVEL
JET DEVELOPS ACROSS THE CENTRAL PLAINS.  WHILE STILL CAN/T RULE OUT
AN ISOLATED STORM THROUGH THE EVENING HOURS...IT DOES APPEAR THAT
THE CAP WILL BE STRONG ENOUGH AHEAD OF THE COLD FRONT AND ASSOCIATED
MID LEVEL WAVE TO LIMIT CONVECTIVE POTENTIAL INITIALLY TO ISOLATED AT
BEST.

MUCH BETTER FOCUS FOR CONVECTION WILL BE ACROSS THE WESTERN REACHES
OF THE STATE IN THE EVENING HOURS ALONG THE COLD FRONT. BASED ON
SHEAR AND STORM MOTION...EXPECTING STORMS TO ORGANIZE INTO A MATURE
MCS AND WORK INTO WESTERN PORTIONS OF THE FORECAST AREA 05-07Z.
EXPECT STORMS TO BE ELEVATED...BUT WITH RELATIVELY DRY LAYER FROM
750 UP TO 300 MB...POTENTIAL FOR STRONG ORGANIZED MCS TO CREATE
DAMAGING WINDS. 0-3 KM BULK SHEAR VECTORS NEAR 30-35 KNOTS ACROSS
THE NORTHERN HALF OF THE FORECAST AREA....INDICATING DAMAGING WIND
POTENTIAL ALONG AND NORTH OF I-90. AS STORMS WORK EAST OF I-29 AFTER
9Z...SEVERE WEATHER PARAMETERS DECREASE AND AM EXPECTING THE
OVERALL INTENSITY TO DECREASE.  WITH THAT SAID...STILL KEPT POPS IN
THE CATEGORICAL RANGE ACROSS THE NORTH CLOSEST TO THE MID LEVEL
WAVE...WITH LESSER CHANCES TO THE SOUTH ESPECIALLY SOUTH OF I-90 AS
ONE GETS FURTHER AWAY FROM THE MID LEVEL WAVE AND THE UPPER JET.
HAVE ADDED MENTION OF CHANCE OF LARGE HAIL AND DAMAGING WINDS TO
WEATHER GRIDS...BUT WAS LESS CONFIDENT EAST OF I-29 AND DECREASED TO
SLIGHT CHANCE ACROSS SOUTHWEST MINNESOTA WHERE SEVERE PARAMETERS
AND SPC OUTLOOK DECREASE.

HAVE COOLED LOWS SLIGHTLY ACROSS THE NORTH  WHERE CONVECTION SEEMS
LIKELY...AND LEFT TEMPERATURES SOUTH OF I-90 QUITE MILD IN THE UPPER
60S WHERE WIDESPREAD RAIN CHANCES ARE.  WITH 0-2 KM VGP AND 0-3 KM
EHI SUGGESTING SUPERCELLS...WILL KEEP MENTION OF LARGE HAIL AND
DAMAGING WINDS IN THE HWO. HAVE ALSO MENTIONED IN THE GRIDS...WITH
LESSER CHANCES OF WIDESPREAD SEVERE EAST OF I-29.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 347 AM CDT FRI JUN 19 2015

ON SATURDAY...THE CONVECTIVE COMPLEX SHOULD BE RAPIDLY EXITING OUR
EASTERN ZONES IN THE MORNING. FURTHERMORE...THE WIND SHIFT TO THE
NORTH AND NORTHWEST IS FORECAST TO MOVE ACROSS THE FORECAST AREA
FAIRLY EARLY IN THE DAY WHICH SHOULD BUILD STORMS AWAY FROM OUR
LOCATION IN THE AFTERNOON. WITH GOOD MIXING POTENTIAL AND SOME DRY
AIR ADVECTION...HIGHS STILL LOOK WARM WITH WIDESPREAD 80S. CURRENTLY
HAVE 89 AT SIOUX CITY BUT WOULD NOT BE SURPRISED IF THEY HIT 90 OR
THE LOWER 90S IF THE MID AND UPPER CLOUD COVER EXITS QUICKLY ENOUGH
BY MIDDAY. HIGH PRESSURE DOMINATES SATURDAY NIGHT...HELPING TO GIVE
LIGHT WINDS AND WHAT SHOULD BE A DRY NIGHT. THEN ON SUNDAY...THE
VARIOUS MODELS INCLUDING THE GFS...ECMWF AND NAM SHOW A WEAK SHORT
WAVE IMPACTING THE FORECAST AREA...ESPECIALLY FOR LOCATIONS WEST OF
I 29 AND NORTH OF I 90 IN OUR SOUTH DAKOTA ZONES. LOW LEVEL MOISTURE
IS A BIT LACKING AFTER THE WIND SHIFT ON SATURDAY...BUT PLENTY OF
MID LEVEL MOISTURE EXISTS WITH SOME DECENT LAPSE RATES BETWEEN 700
AND 500MB. THEREFORE CHANCE POPS ARE WARRANTED IN THE AFOREMENTIONED
AREA WITH LESS CHANCES ELSEWHERE.

ON SUNDAY NIGHT...SUNDAYS MID LEVEL SHORT WAVE WEAKENS IN OUR
EASTERN ZONES AS IT MOVES EASTWARD...REPLACED BY A STRONG SHORT
WAVE RAPIDLY MOVING SOUTHEASTWARD ACROSS NORTH DAKOTA AND THE
NORTHERN HALF OF MINNESOTA. MOST OF THE DYNAMICS REMAINS NORTH OF
THE FORECAST AREA...SO THEREFORE ONLY CHANCE POPS ARE WARRANTED
WITH THE HIGHEST POPS ALONG THE HIGHWAY 14 CORRIDOR IN OUR
NORTHERN ZONES. LOWS STILL LOOK MILD...ABOUT 60 TO 65 DEGREES WITH
THE WINDS CHANGING TO THE NORTH BEHIND THE SHORT WAVE PASSAGE LATE
AT NIGHT.

CONFIDENCE IS RATHER LOW IN THE EXTENDED IN TERMS OF WHEN AND WHERE
THUNDERSTORM CHANCES ARE. IN GENERAL...BOTH THE GFS AND ECMWF ARE
SHOWING AN UPPER RIDGE BUILDING ACROSS THE SOUTHERN HALF OF THE
UNITED STATES WITH A BRISK QUASI ZONAL FLOW THROUGHOUT THE NORTHERN
HALF. THIS TYPE OF PATTERN SHOULD GIVE MILD TEMPERATURES THROUGHOUT
THE FORECAST...WITH HIGHS IN THE UPPER 70S TO MID 80S BASED ON THE
LATEST 850MB TEMPERATURES OFF OF THE LATEST ECMWF AND GFS. LOWS ARE
PRIMARILY IN THE LOWER AND MID 60S...BUT IF WE GET LIGHT WINDS
COUPLED WITH CLEAR SKIES...WOULD NOT BE SURPRISED IF LOWS ERROR
ON THE COOL SIDE OF SUPERBLEND LOWS HERE AND THERE. DUE TO THE
DIFFERENCE BETWEEN THE VARIOUS MODELS WITH SPECIFIC SHORT WAVE
TIMING MOVING ACROSS THE FAST UPPER FLOW...PIN POINTING RAIN CHANCES
IS REAL PROBLEMATIC. AT THIS TIME...THERE DOES NOT LOOK TO BE A
WIDESPREAD RAIN EVENT. THE ONE EXCEPTION TO THIS WHERE THERE IS SOME
AGREEMENT IS IN NORTHWEST IOWA AND EXTREME NORTHEAST NEBRASKA LATE
TUESDAY NIGHT AND WEDNESDAY MORNING. HOWEVER...BOTH MODELS LOOK LIKE
THEY DEVELOP A CONVECTIVELY INDUCED SHORT WAVE...THEREFORE THE SHORT
WAVE IN THAT AREA MAY BE A RESPONSE TO CONVECTIVE FEEDBACK. VERY
DIFFICULT TO TELL THIS FAR OUT. THERE IS AN 850MB BOUNDARY CLOSE TO
NORTHWEST IOWA...AT LEAST EXTENDING THROUGH THE SOUTHERN PORTION OF
NORTHWEST IA. SO ITS WORTH WATCHING BUT HIGH POPS ARE NOT WARRANTED
YET AT THIS TIME. ANOTHER WEAK COLD FRONT MOVES THROUGH LATER
WEDNESDAY NIGHT AND THURSDAY MORNING...BUT AT THIS TIME THE FRONTAL
PASSAGE DOES NOT LOOK TO HAVE A LOT OF SHOWER OR STORM ACTIVITY WITH
IT. ONE THING OF INTEREST IS THE LONGER RANGE STILL SHOWS THE UPPER
RIDGE MIGRATING AND BUILDING ACROSS THE WESTERN UNITED STATES BEYOND
THE EXTENDED PERIOD. THAT WOULD PUT THE NORTHERN PLAINS IN A SHORT
NORTHWEST FLOW ALOFT FOR THIS TIME OF YEAR.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1213 PM CDT FRI JUN 19 2015

MAIN CONCERN WITH CONVECTIVE SYSTEM EXPECTED TO PUSH ACROSS THE
KHON AREA AROUND MIDNIGHT...KFSD A COUPLE HOURS LATER...AND
CLIPPING PAST KSUX. VERY STRONG WINDS WILL LIKELY ACCOMPANY THE
STORMS...WITH POTENTIAL FOR KHON AREA FOR GUSTS OF 60 TO 65 KTS.
LIKELY TO FIND BRIEF PERIODS OF IFR CONDITIONS IN THUNDERSTORMS...
BUT WILL LIKELY LIMIT MENTION OVER A COUPLE HOURS TO MVFR AT THIS
TIME.

&&

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

UPDATE...CHAPMAN
SHORT TERM...
LONG TERM...MJ
AVIATION...CHAPMAN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
746 AM CDT FRI JUN 19 2015

MNZ071-SDZ038>040-052>061-201300-
LINCOLN MN-BEADLE-KINGSBURY-BROOKINGS-JERAULD-SANBORN-MINER-LAKE-
MOODY-BRULE-AURORA-DAVISON-HANSON-MCCOOK-
746 AM CDT FRI JUN 19 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
MINNESOTA...EAST CENTRAL SOUTH DAKOTA...SOUTH CENTRAL SOUTH
DAKOTA AND SOUTHEAST SOUTH DAKOTA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED THUNDERSTORMS THROUGH MIDDAY WILL NOT BE SEVERE.

A LARGER COMPLEX OF THUNDERSTORMS IS EXPECTED TO ORGANIZE THIS
EVENING ACROSS CENTRAL SOUTH DAKOTA...AND PRESS EAST AND SOUTHEAST
OVERNIGHT. THESE STORMS WILL HAVE A HIGHER PROBABILITY OF
PRODUCING A SWATH OF DAMAGING WINDS TO AROUND 70 MPH ACROSS AREAS
MAINLY NORTH OF INTERSTATE 90...AND ESPECIALLY CLOSER TO THE
HIGHWAY 14 CORRIDOR FROM HURON TO BROOKINGS. THE INITIAL SEVERE
STORM THREAT SHOULD DEVELOP FROM HURON TO CHAMBERLAIN BY AROUND
10 PM...AND PEAK IN THE POST MIDNIGHT HOURS. WHILE DAMAGING WIND
IS THE GREATEST THREAT...A FEW STORMS WILL BE CAPABLE OF HAIL UP
TO HALF DOLLAR SIZE. A PERIOD OF HEAVY RAINFALL IS ALSO LIKELY
WITH STORMS...WHICH COULD OVERWHELM SOME POOR DRAINAGE LOCATIONS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

PERIODIC THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH THE FIRST HALF
OF NEXT WEEK...THOUGH AT THIS TIME THE POTENTIAL FOR SEVERE STORMS
IS UNCERTAIN.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY TONIGHT BETWEEN 10 PM AND 4 AM.

IAZ001>003-012>014-020-MNZ072-080-081-089-090-097-098-SDZ050-
062>071-201300-
LYON IA-OSCEOLA-DICKINSON-SIOUX-O'BRIEN-CLAY IA-PLYMOUTH-LYON MN-
MURRAY-COTTONWOOD-NOBLES-JACKSON-PIPESTONE-ROCK-GREGORY-MINNEHAHA-
CHARLES MIX-DOUGLAS-HUTCHINSON-TURNER-LINCOLN SD-BON HOMME-
YANKTON-CLAY SD-UNION-
746 AM CDT FRI JUN 19 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST
IOWA...SOUTHWEST MINNESOTA...SOUTH CENTRAL SOUTH DAKOTA AND
SOUTHEAST SOUTH DAKOTA.

.DAY ONE...TODAY AND TONIGHT

AN ISOLATED THUNDERSTORM WILL BE POSSIBLE FROM LATER THIS MORNING
INTO THE EARLY AFTERNOON NEAR AND NORTH OF INTERSTATE 90. THESE
STORMS THROUGH EARLY AFTERNOON WILL NOT BE SEVERE.

A COMPLEX OF THUNDERSTORMS WILL DEVELOP ACROSS CENTRAL SOUTH
DAKOTA LATER THIS EVENING...AND PUSH EAST AND SOUTHEAST THROUGH
THE OVERNIGHT HOURS...MAINLY AFTER MIDNIGHT. THE GREATER THREAT
WITH THUNDERSTORMS WILL BE POCKETS OF DAMAGING WIND TO 70
MPH...ALTHOUGH A FEW STORMS MAY PRODUCE HAIL UP TO QUARTER TO HALF
DOLLAR SIZE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

PERIODIC THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH THE FIRST HALF
OF NEXT WEEK...THOUGH AT THIS TIME THE POTENTIAL FOR SEVERE STORMS
IS UNCERTAIN.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE POSSIBLE AFTER MIDNIGHT.

IAZ021-022-031-032-NEZ013-014-201300-
CHEROKEE-BUENA VISTA-WOODBURY-IDA-DIXON-DAKOTA-
746 AM CDT FRI JUN 19 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST IOWA
AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

THERE WILL BE A CHANCE FOR THUNDERSTORMS LATE FRIDAY NIGHT. A FEW
STORMS WILL BE CAPABLE OF WINDS TO 50 MPH...HEAVY RAINFALL...AND
SOME SMALL HAIL UP TO ONE HALF INCH IN DIAMETER.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

PERIODIC THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH THE FIRST
HALF OF NEXT WEEK...THOUGH AT THIS TIME THE POTENTIAL FOR SEVERE
STORMS IS UNCERTAIN.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.