SWODY1
SPC AC 191952
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0252 PM CDT THU APR 19 2012
VALID 192000Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM FAR NRN TX ACROSS OK...ERN
KS...WRN MO AND SRN IA...
...N TX...OK...
TIGHTENED UP THE SEVERE PROBABILITIES ON THE S SIDE OVER NRN TX DUE
TO EXPECTED CAPPING AND MODELS SHOWING THE PRIMARY CORRIDOR OF
STORMS TO BE OVER SRN OK AND ALONG THE RED RIVER. THE STEEP LAPSE
RATE ENVIRONMENT AS WELL AS FORCING AND VEERING WIND PROFILES WITH
HEIGHT SHOULD FAVOR A FEW SUPERCELLS CAPABLE OF LARGE HAIL...PERHAPS
TRANSITIONING INTO A WIND THREAT AS OUTFLOW PRODUCTION INCREASES AND
FLOW ALOFT IS NOT VERY STRONG.
...ERN KS INTO WRN MO AND IA...
STRONG SHEAR BUT WEAK INSTABILITY SHOULD SUPPORT STRONG TO
MARGINALLY SEVERE STORMS ALONG THE COLD FRONT LATER THIS AFTERNOON
INTO THE EARLY EVENING. THE AIR MASS IS RELATIVELY DRY BUT
PERSISTENT LIFT SHOULD ALLOW FOR SCATTERED ACTIVITY. STRONG WIND
PROFILES AND STEEP LOW LEVEL LAPSE RATES SHOULD FAVOR WIND
GUSTS...WITH MARGINAL HAIL POSSIBLE AS WELL.
FARTHER N INTO IA...LOW LEVEL SHEAR IS STRONGER DUE TO A WARM FRONT.
STORMS THAT INTERACT WITH THIS BOUNDARY COULD HAVE A THREAT OF A
TORNADO...ALTHOUGH LIKELY WEAK AND SHORT LIVED. FOR MORE INFORMATION
ON THIS AREA SEE MESOSCALE DISCUSSION 566.
..JEWELL.. 04/19/2012
.PREV DISCUSSION... /ISSUED 1131 AM CDT THU APR 19 2012/
...ERN KS TO WRN MO...
SURFACE LOW ACROSS KS THIS MORNING WILL TRACK NEWD TO NRN MO/SRN IA
BY EVENING IN RESPONSE TO SHORT WAVE TROUGH AMPLIFICATION ACROSS THE
CNTRL/SRN PLAINS. COLD FRONT TRAILING SWWD FROM THE LOW WILL SPREAD
INTO ERN/SERN KS AND NWRN MO THROUGH THE EVENING AND THEN ACROSS
MOST OF MO THROUGH EARLY FRIDAY.
STRONG DYNAMICS AND LESSENING DEEP LAYER STATIC STABILITY WILL
CONTRIBUTE TO STRONG ASCENT WITH THIS SYSTEM. CONSEQUENT LOW-LEVEL
MASS ADJUSTMENTS WILL SUPPORT MODEST WARM SECTOR MOISTURE ADVECTION
THAT...WHEN COMBINED WITH EVAPOTRANSPIRATION...MAY RESULT IN SURFACE
DEWPOINTS REACHING THE MID 50S F AND A NARROW CORRIDOR OF SBCAPE
AROUND 500-1000 J/KG FROM ERN KS INTO NRN MO. PRESENT INDICATIONS
ARE THAT SUBSTANTIALLY MORE BOUNDARY LAYER MOISTENING AND HEATING
WILL BE REQUIRED TO OVERCOME THE MAGNITUDE OF ANTECEDENT CONVECTIVE
INHIBITION IN THE PRE-FRONTAL AIRMASS THROUGH LATE THIS AFTERNOON.
THUS...MOST LIKELY SCENARIO FOR CONVECTIVE INITIATION APPEARS TO BE
TSTM DEVELOPMENT OCCURRING IMMEDIATELY ALONG AND/OR IN THE WAKE OF
COLD FROPA WHERE FOCUSED MESOSCALE ASCENT IN CONCERT WITH LARGER
SCALE FORCING CAN ACT TO OVERCOME STRONG CAPPING.
BULK SHEAR OF 35-40KT WILL LIKELY AID IN UPDRAFT PERSISTENCE AND THE
PRESENCE OF COLD/DRY AIR ALOFT SHOULD FURTHER ENHANCE HAIL
PRODUCTION AS QLCS SPREADS ESEWD ACROSS SERN KS AND INTO MO THROUGH
THE LATE EVENING. STRONGER WIND GUST POTENTIAL APPEARS MOST LIKELY
WITH INITIAL ACTIVITY OVER KS/NWRN MO PRIOR TO POST-FRONTAL AND
DIURNAL BOUNDARY LAYER COOLING SETTING IN.
...OK TO NW TX...
REVIEW OF LATEST HIGH-RESOLUTION GUIDANCE AND SURFACE/UA ANALYSIS
SUGGEST THAT TSTM DEVELOPMENT ACROSS OK AND NW TX MAY BE DELAYED
UNTIL AROUND 00Z. WHILE THESE AREAS ARE IN CLOSER PROXIMITY TO
RETURNING LOW LEVEL MOISTURE...MORE SUBSTANTIAL LOW LEVEL THETA-E
REMAINS WELL TO THE SOUTH AND...EVEN WITH
EVAPOTRANSPIRATION...SURFACE DEWPOINTS MAY STRUGGLE TO REACH 60F.
STRONG HEATING AND DEEP MIXING THROUGH THE AFTERNOON WILL FURTHER
OFFSET ANY EARLY/PERCEIVED GAINS IN BOUNDARY LAYER MOISTURE IN THESE
AREAS BUT A CORRIDOR OF CAPPED SBCAPE NEARING 2000 J/KG SEEMS
POSSIBLE JUST AHEAD OF THE COLD FRONT AND DRYLINE.
EXPECT COLD FRONT...CURRENTLY SITUATED FROM NWRN OK SWWD ACROSS THE
TX PNHDL...TO MOVE INTO CNTRL OK THROUGH LATE AFTERNOON AS COLD
FRONT/DRYLINE INTERSECTION BECOMES ESTABLISHED ACROSS SWRN OK/NWRN
TX. TSTM INITIATION IN THIS SCENARIO APPEARS MOST LIKELY NEAR
FRONT/DRYLINE INTERSECTION SOMEWHERE NEAR/SOUTH OF RED RIVER IN THE
23-01Z TIME FRAME. SUPERCELL SHEAR PROFILES ARE INDICATED IN
FORECAST SOUNDINGS ACROSS THIS AREA BUT DEEP BOUNDARY LAYER/HIGH LFC
SHOULD LIMIT TORNADO POTENTIAL TO VERY ISOLATED AND BRIEF IF AT ALL.
LARGE HAIL DOES APPEAR LIKELY WITH THIS DEVELOPMENT BUT OVERALL
STORM COVERAGE AS CURRENTLY INDICATED IN AVAILABLE GUIDANCE DOES NOT
APPEAR TO WARRANT SIGNIFICANT HAIL PROBABILITIES.
ADDITIONAL STORMS ARE POSSIBLE ALONG THE FRONT FROM NERN INTO CNTRL
OK THROUGH THE EVENING. STORM EVOLUTION HERE WILL NOT BE MUCH
DIFFERENT THAN THAT DESCRIBED FOR KS/MO. A LOW AMPLITUDE BUT
PRONOUNCED MID LEVEL DISTURBANCE NOW CROSSING THE FOUR CORNERS AREA
MAY ENHANCE THE POTENTIAL POST-FRONTAL MCS DEVELOPMENT ACROSS THE
TX/OK PNHDLS LATE AND THIS ACTIVITY MAY SPREAD INTO WRN AND CNTRL OK
THROUGH THE NIGHT WITH A CONTINUED THREAT FOR HAIL.
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