Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 031629
SWODY1
SPC AC 031627

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT WED JUN 03 2015

VALID 031630Z - 041200Z

...THERE IS AN ENH RISK OF SVR TSTMS FROM ERN PARTS OF WY/CO INTO
SRN NEB/NRN KS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL HIGH PLAINS TO
THE MID AND LOWER MO VALLEY...

...THERE IS A MRGL RISK OF SVR TSTMS FROM A PART OF THE NRN ROCKIES
INTO THE UPPER MIDWEST AND OZARKS...

...THERE IS A MRGL RISK OF SVR TSTMS OVER THE SERN STATES...

...SUMMARY...
SEVERE STORMS WITH VERY LARGE HAIL AND TORNADOES WILL OCCUR OVER
PARTS OF COLORADO...WYOMING INTO SOUTHERN NEBRASKA AND NORTHERN
KANSAS THIS AFTERNOON AND EVENING.  OTHER MORE ISOLATED SEVERE
STORMS WILL BE POSSIBLE LATER TODAY INTO TONIGHT OVER SURROUNDING
LOCATIONS FROM THE CENTRAL HIGH PLAINS INTO THE MIDDLE AND LOWER
MISSOURI VALLEY.  A FEW STRONG STORMS MAY OCCUR THIS AFTERNOON OVER
PARTS OF THE SOUTHEAST.

...SYNOPSIS...

FURTHER INTENSIFICATION OF THE WRN U.S. TROUGH IS FORECAST DURING
THE DAY ONE PERIOD WITH A RESULTANT DOWNSTREAM BUILDING OF A RIDGE
OVER THE N-CNTRL STATES.  BETWEEN THESE FEATURES...A LOW-AMPLITUDE
SHORT-WAVE TROUGH WILL TRACK FROM THE LOWER CO VALLEY THROUGH THE
CNTRL ROCKIES INTO NRN/CNTRL HIGH PLAINS BY 12Z/THU.  ELSEWHERE...AN
UPPER LOW OVER THE SRN APPALACHIANS WILL DRIFT ONLY SLIGHTLY EWD.

AT THE SURFACE...AN AREA OF LOW PRESSURE OVER CNTRL MN WILL DEVELOP
INTO CNTRL WI WITH A TRAILING COLD FRONT SETTLING SEWD AND LINKING
WITH A LEE CYCLONE OVER THE CNTRL HIGH PLAINS.  AHEAD OF THIS
FRONT...AN OVERNIGHT MCS HAS GENERATED AN OUTFLOW BOUNDARY WHICH
STRETCHES FROM W-CNTRL MO TO W-CNTRL KS AS OF MID MORNING.

...CO FRONT RANGE INTO THE LOWER MO VALLEY/OZARKS THIS AFTERNOON
INTO TONIGHT...

CONVECTIVE OUTFLOW ASSOCIATED WITH THE ABOVE-MENTIONED MCS IS
ENHANCING THE WWD FLUX OF AN INCREASING MOIST BOUNDARY LAYER INTO
THE CNTRL HIGH PLAINS...BENEATH OF PLUME OF STEEP MID-LEVEL LAPSE
RATES PER 12Z LBF/DNR/DDC RAOBS.  THESE PROCESSES COUPLED WITH
DAYTIME HEATING WILL RESULT IN A MODERATELY UNSTABLE AIR MASS WITH
AFTERNOON MLCAPE VALUES APPROACHING 1500-2500 J/KG.  OVER LOWER
ELEVATIONS OF THE CNTRL PLAINS...RICHER BOUNDARY-LAYER MOISTURE WILL
PROMOTE EVEN STRONGER INSTABILITY /MLCAPE OF 2000-3500+ J PER KG/ TO
THE SOUTH OF THE LINGERING CLOUDS AND CONVECTIVE OUTFLOW.

WHILE FORCING FOR ASCENT ASSOCIATED WITH THE LOWER CO VALLEY IMPULSE
WILL LIKELY REMAIN TO THE WEST OF THE HIGH PLAINS THROUGH THE PEAK
OF THE DIURNAL HEATING CYCLE...LOW-LEVEL UPSLOPE FLOW INTO THE CO
FRONT RANGE AND CHEYENNE RIDGE WILL BE SUFFICIENT TO INITIATE WIDELY
SCATTERED STORMS LATER TODAY.  VERTICALLY VEERING WIND PROFILES WITH
40-50 KT OF DEEP-LAYER SHEAR WILL SUPPORT A RAPID EVOLUTION OF THE
INITIAL STORMS INTO SUPERCELLS WITH A RISK FOR LARGE HAIL AND A FEW
TORNADOES.  LATE THIS EVENING INTO TONIGHT...STORMS MAY MERGE INTO
CLUSTERS OR AN MCS WITH A DAMAGING WIND AND HAIL THREAT SPREADING
EWD ACROSS THE CNTRL HIGH PLAINS.

FARTHER EAST...FROM CNTRL/ERN PARTS OF NEB/KS INTO THE LOWER MO
VALLEY INTO OZARKS...SPECIFIC DETAILS REGARDING STORM EVOLUTION
REMAIN UNCLEAR.  A SUBSET OF THE MORNING STORMS PRESENT OVER NERN KS
INTO NWRN MO MAY RE-INTENSIFY LATER THIS MORNING INTO AFTERNOON
OWING TO THE EXISTENCE OF AT LEAST A WEAK MCV AND LOW-LEVEL UPLIFT
ALONG AN ACTIVE COLD POOL.  GIVEN THE POTENTIAL FOR MODERATE TO
STRONG INSTABILITY AND MODEST VERTICAL SHEAR ACROSS THE INFLOW AIR
MASS...THIS SCENARIO WOULD SUPPORT SOME STORM ORGANIZATION AND A
RISK FOR LARGE HAIL AND DAMAGING WINDS FROM PARTS OF ERN KS INTO
WRN/CNTRL MO THIS AFTERNOON INTO EVENING.

OTHER STORMS ARE LIKELY TO FORM LATER THIS AFTERNOON INTO EVENING
ALONG THE OUTFLOW BOUNDARY AND/OR SYNOPTIC FRONT OVER S-CNTRL NEB OR
N-CNTRL KS...AS WELL AS A LEE TROUGH OVER WRN KS.  THE LOCAL
ENVIRONMENT WILL BE QUITE FAVORABLE FOR SUPERCELLS CAPABLE OF LARGE
HAIL AND A COUPLE OF TORNADOES WITHIN THE FIRST FEW HOURS AFTER
INITIATION.  THEREAFTER...STORMS MAY GROW UPSCALE INTO AN MCS WITH A
RISK FOR AT LEAST ISOLATED OCCURRENCES OF WIND AND HAIL PERSISTING
ACROSS THE CNTRL PLAINS INTO THE OVERNIGHT HOURS.

...SERN STATES THIS AFTERNOON...

SIMILAR TO PREVIOUS DAYS...THE INTERACTION OF A MOIST AND MODERATELY
UNSTABLE AIR MASS WITH FORCING FOR ASCENT ASSOCIATED WITH THE
UPPER-AIR SYSTEM WILL FOSTER WIDESPREAD STORMS...A FEW OF WHICH WILL
PRODUCE SOME HAIL AND LOCALLY DAMAGING WINDS.

..MEAD/LEITMAN.. 06/03/2015



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