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Apr 3, 2014 1630 UTC Day 1 Convective Outlook

April 3, 2014

Apr 3, 2014 1630 UTC Day 1 Convective Outlook

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DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT THU APR 03 2014

VALID 031630Z – 041200Z

…THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT OVER MUCH OF CNTRL AND SRN MO…MOST OF AR…NERN LA…NWRN MS…WRN PARTS OF TN/KY…SRN IL…AND FAR SWRN IND…

…THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MO VALLEY AND OH VALLEY SWD INTO ERN TX AND THE LOWER MS VALLEY…

…SYNOPSIS…

A POSITIVELY TILTED MIDLEVEL TROUGH OVER THE CNTRL AND SRN ROCKIES WILL ASSUME AN INCREASING NEGATIVE TILT AND EVENTUALLY FORM A CLOSED MIDLEVEL CIRCULATION AS IT TRANSLATES INTO THE UPPER MIDWEST AND MID MS VALLEY BY 04/12Z. THIS SYSTEM WILL BE ATTENDED BY A MIDLEVEL JET STREAK OF 70-90 KT AND A CORRIDOR OF 500-MB HEIGHT FALLS OF 100-150 M / 12 HR.

AT THE SURFACE…AN AREA OF LOW PRESSURE OVER ERN KS WILL DEVELOP TO N-CNTRL MO/S-CNTRL IA BY 04/00Z PRIOR TO OCCLUDING OVER SRN WI BY THE END OF THE PERIOD. A TRAILING COLD FRONT INITIALLY FROM THE LOW PRESSURE INTO SRN HIGH PLAINS WILL SWEEP EWD THROUGH THE MID MS VALLEY AND MORE SEWD INTO THE LOWER MS VALLEY BY DAYBREAK FRIDAY. MEANWHILE…THE MOVEMENT OF AN ASSOCIATED WARM FRONT NWD THROUGH THE OH VALLEY WILL BE MODULATED BY AN ONGOING MCS OVER THE REGION. FINALLY…A DRYLINE EXTENDING FROM SWRN OK INTO W-CNTRL TX WILL MIX EWD TODAY…PROGRESSIVELY BEING OVERTAKEN BY THE COLD FRONT FROM THE NW.

–POTENTIALLY WIDESPREAD SEVERE WEATHER EPISODE FROM THE OZARK PLATEAU EWD INTO THE MIDDLE AND LOWER MS VALLEYS AND LOWER OH VALLEY.–

…LOWER MO AND OH VALLEYS SWD INTO ERN TX AND THE LOWER MS VALLEY…

12Z OBSERVED SOUNDINGS WITHIN THE NWD-EXPANDING WARM SECTOR EXHIBITED A MOIST BOUNDARY LAYER /LOWEST 100-MB MEAN-MIXING RATIOS OF AROUND 13 G PER KG/ SURMOUNTED BY AN EML WHICH WAS ASSOCIATED WITH 700-500-MB LAPSE RATES OF 8.0-8.5 C/KM. WHERE STRONGER DAYTIME HEATING CAN OCCUR…THESE CONDITIONS WILL YIELD AFTERNOON MLCAPE VALUES APPROACHING 1500-3000+ J/KG.

AS OF 16Z…A COUPLE OF SEPARATE CONVECTIVE REGIMES WERE ONGOING: 1) AN MCS WITH WELL-DEFINED MCV OVER THE OH VALLEY WITH ASSOCIATED TSTM CLUSTERS OCCURRING ALONG THE TRAILING OUTFLOW BOUNDARY INTO E-CNTRL IL… AND 2) OPEN WARM SECTOR STORMS FROM SWRN/S-CNTRL MO SWWD INTO SERN OK. ISOLATED OCCURRENCES OF DAMAGING WINDS AND HAIL WILL EXIST WITH THE FORMER ACTIVITY AS IT PERSISTS OVER THE OH VALLEY TODAY. MEANWHILE…THE LATTER REGIME WILL REMAIN COLOCATED WITH A MORE STRONGLY SHEARED AND UNSTABLE ENVIRONMENT WHICH WILL BE QUITE SUPPORTIVE OF SUPERCELLS CAPABLE OF VERY LARGE HAIL AND TORNADOES AS IT CONTINUES NEWD THROUGH PARTS OF SRN MO AND AR THIS AFTERNOON INTO EVENING.

IN THE WAKE OF THESE INITIAL STORMS…MODEL GUIDANCE REMAINS FAIRLY CONSISTENT IN THE DEVELOPMENT OF ADDITIONAL TSTMS BY AFTERNOON FROM THE VICINITY OF THE SURFACE TRIPLE POINT OVER WRN MO SWD ALONG THE COLD FRONT INTO ERN OK…AND PERHAPS AS FAR SOUTH AS THE DRYLINE INTO ERN TX AS DCVA ATTENDANT TO THE MIDLEVEL TROUGH BEGINS TO OVERSPREAD THE WARM SECTOR. UNCERTAINTY EXISTS WITH REGARD TO WHAT IMPACT THE INITIAL STORMS WILL HAVE ON THIS SUBSEQUENT DEVELOPMENT. BUT IN GENERAL…IT DOES APPEAR THAT THE ENVIRONMENT WILL FEATURE A FAVORABLE OVERLAP OF MODERATE INSTABILITY AND RELATIVELY STRONG LOW-LEVEL AND DEEP-LAYER SHEAR WHICH WILL PROMOTE SUPERCELLS AND BOWING STRUCTURES CAPABLE OF VERY LARGE HAIL…TORNADOES /SOME POTENTIALLY STRONG/ AND DAMAGING WINDS.

EXPECT THIS ACTIVITY TO EVENTUALLY GROW UPSCALE INTO A LINEAR CONVECTIVE SYSTEM ALONG THE EWD/SEWD SURGING COLD FRONT WITH INCREASING POTENTIAL FOR WIDESPREAD DAMAGING WINDS TONIGHT ACROSS PARTS OF THE MID AND LOWER MS VALLEY INTO LOWER OH VALLEY. THE OVERNIGHT TORNADO THREAT REMAINS MORE UNCERTAIN AS LATEST MODEL GUIDANCE IS NOT AS SUGGESTIVE OF THE DEVELOPMENT OF A PRE-FRONTAL CONFLUENCE BAND DEVELOPING OVER THE LOWER MS VALLEY WHICH WOULD BE SUPPORTIVE OF MORE DISCRETE SUPERCELL DEVELOPMENT.

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