DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 301957
SWODY1
SPC AC 301955

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT TUE JUL 30 2013

VALID 302000Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE NRN/CNTRL
PLAINS INTO THIS EVENING...

...NRN/CNTRL PLAINS...
SURFACE-BASED TSTM INITIATION IS UNDERWAY OVER WRN SD /REF WW 452/.
PREVIOUS FORECAST REASONING IS LARGELY ON-TRACK...WITH CHANGES TO
SPATIAL EXTENT OF PROBABILITIES BASED PRIMARILY ON EXTRAPOLATED
THERMODYNAMIC ENVIRONMENT AND 12Z WRF-NSSL/NMM GUIDANCE. HAVE
INTRODUCED A NARROW 5 PERCENT TORNADO PROBABILITY ALONG THE COOL
SIDE OF THE SURFACE FRONT/LEE TROUGH IN PARTS OF WRN SD GIVEN THE
EXPECTATION OF SUPERCELLS DEVELOPING SEWD ALONG THIS CORRIDOR.

...ERN OK TO THE MID-SOUTH...
ABUNDANT CLOUD COVERAGE AND STRATIFORM RAINFALL HAS LIMITED
DESTABILIZATION INVOF THE MCV CENTERED OVER SERN MO. AS SUCH...MORE
ROBUST HEATING HAS REMAINED DIVORCED FROM THE STRONGER ASCENT
ASSOCIATED WITH THE MCV. NEVERTHELESS...POTENTIAL DOES REMAIN FOR
SURFACE-BASED STORMS TO FORM BY EARLY EVENING ALONG THE MS/AL BORDER
AND OVER ERN OK. ANY ACTIVITY OVER ERN OK IS MOST LIKELY TO PERSIST
THIS EVENING INTO THE OVERNIGHT WITH A MODEST WLY LLJ SUPPORTING
ISENTROPIC LIFT ACROSS THE MID-SOUTH. LOCALIZED MICROBURSTS WILL BE
THE PRIMARY HAZARD WITHIN A HIGH PW ENVIRONMENT.

..GRAMS.. 07/30/2013

.PREV DISCUSSION... /ISSUED 1124 AM CDT TUE JUL 30 2013/

...SYNOPSIS...

THE LARGE-SCALE PATTERN WILL REMAIN CHARACTERIZED BY A PROMINENT
UPPER-LEVEL ANTICYCLONE CENTERED OVER THE SRN ROCKIES INTO SRN HIGH
PLAINS WITH A BELT OF ENHANCED MID TO UPPER-LEVEL FLOW ALONG THE NRN
PERIPHERY OF THIS FEATURE ACROSS THE NRN TIER OF STATES. A SERIES
OF LOW-AMPLITUDE PERTURBATIONS WILL TRANSLATE EWD WITHIN THIS
HIGH-MOMENTUM AIR STREAM FROM THE NRN INTERMOUNTAIN REGION AND NRN
HIGH PLAINS INTO THE GREAT LAKES...AHEAD OF AN AMPLIFYING MIDLEVEL
TROUGH OVER CNTRL CANADA.

IN THE LOW LEVELS...A WEAK COLD FRONT WILL CONTINUE EWD INTO THE
UPPER GREAT LAKES WITH THE TRAILING EXTENSION OF THIS BOUNDARY
SETTLING SWD THROUGH THE NRN HIGH PLAINS. A SURFACE LOW CURRENTLY
JOINED WITH THE FRONT OVER NERN WY WILL DEVELOP EWD INTO WRN SD
TODAY WHILE A LEE TROUGH STRENGTHENS ACROSS THE CNTRL HIGH PLAINS.
FARTHER TO THE SOUTH...A WEAK COLD FRONT WILL SLOWLY ADVANCE SWD
ACROSS THE SRN PLAINS.

...NRN/CNTRL PLAINS THIS AFTERNOON INTO TONIGHT...

12Z REGIONAL SOUNDINGS SHOWED THE PRESENCE OF A RELATIVELY MOIST
BOUNDARY LAYER /I.E. LOWEST 100-MB MEAN-MIXING RATIOS OF 11-12 G PER
KG/ BENEATH STEEP MIDLEVEL LAPSE RATES WHICH WILL CONTRIBUTE TO A
MODERATELY UNSTABLE AIR MASS BY AFTERNOON WITH MLCAPE OF 1000-1500
J/KG. CONVERGENCE ALONG THE COLD FRONT AND LEE TROUGH COUPLED WITH
THE INFLUENCE OF MIGRATORY MIDLEVEL PERTURBATIONS MOVING OUT OF THE
NRN HIGH PLAINS WILL FOSTER WIDELY SCATTERED TSTMS LATER TODAY
AMIDST A KINEMATIC ENVIRONMENT FEATURING A VERTICALLY VEERING WIND
PROFILE WITH 40-50 KT OF DEEP-LAYER SHEAR. AS SUCH...THE POTENTIAL
WILL EXIST FOR SUPERCELLS CAPABLE OF LARGE HAIL AND DAMAGING WINDS.
STORMS MAY COALESCE INTO SEWD-MOVING CLUSTERS BY THIS EVENING WITH A
CONTINUED RISK FOR HAIL AND HIGH WINDS.

OTHER ISOLATED STORMS MAY FORM OFF THE HIGH TERRAIN OF SRN MT/NRN WY
WITHIN THE POST-FRONTAL ENVIRONMENT THIS AFTERNOON AND EVENING.
WHILE INSTABILITY WILL BE LIMITED...VERTICAL SHEAR WILL BE
RELATIVELY STRONG AND SUPPORTIVE OF UPDRAFT ROTATION WITH A RISK FOR
HAIL AND STRONG WIND GUSTS.

...OK INTO THE MID SOUTH AND CNTRL GULF COAST STATES THIS AFTERNOON
AND EVENING...

A FAIRLY WELL-DEFINED MCV IS APPARENT THIS MORNING OVER S-CNTRL MO
WITH THIS FEATURE CONTINUING EWD ACROSS THE MID SOUTH TODAY.
FORCING ASSOCIATED WITH THIS FEATURE WILL COMBINE WITH LOW-LEVEL
CONVERGENCE ALONG A WARM FRONT LIFTING NWD ACROSS THE MID SOUTH TO
PROMOTE WIDELY SCATTERED AFTERNOON TSTMS. THOUGH VERTICAL SHEAR
WILL NOT BE PARTICULARLY STRONG...THE PRESENCE OF A MOIST AND
MODERATE TO STRONGLY UNSTABLE AIR MASS WILL BE SUPPORTIVE OF STRONG
TO MARGINALLY SEVERE STORMS CAPABLE OF LOCALLY DAMAGING WIND GUSTS.
OTHER INTENSE STORMS WILL BE POSSIBLE THIS AFTERNOON ALONG THE
TRAILING COLD FRONT AND OUTFLOW BOUNDARY ACROSS THE OZARK PLATEAU.
HERE TOO...THE PRIMARY HAZARD WILL BE ISOLATED DAMAGING WIND GUSTS.

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