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May 10, 2014 1630 UTC Day 1 Convective Outlook

May 10, 2014

May 10, 2014 1630 UTC Day 1 Convective Outlook

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DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1125 AM CDT SAT MAY 10 2014

VALID 101630Z – 111200Z

…THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE CNTRL PLAINS INTO MID MS VALLEY…

…SUMMARY…
WIDELY SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED LATE THIS AFTERNOON INTO TONIGHT FROM PARTS OF NEBRASKA AND KANSAS EASTWARD INTO MUCH OF MISSOURI AND SOUTHERN IOWA. LARGE HAIL WILL BE THE PRIMARY SEVERE THREAT…ALTHOUGH TORNADOES AND LOCALLY DAMAGING WIND ALSO WILL BE POSSIBLE.

…SYNOPSIS…

THE PROGRESSION OF MID AND UPPER-LEVEL WIND MAXIMA FROM OFF THE ORE/CA COASTS INTO LOWER CO VALLEY WILL CONTRIBUTE TO THE INTENSIFICATION OF A SHORT-WAVE TROUGH OVER THE INTER-MOUNTAIN WEST…AND DOWNSTREAM RIDGING ACROSS THE MID/LOWER MO VALLEY INTO UPPER GREAT LAKES. EMBEDDED WITHIN THIS BROADER-SCALE FLOW PATTERN…A SHORT-WAVE TROUGH OVER THE MID MS VALLEY WILL TRANSLATE ENEWD THROUGH THE OH VALLEY TODAY…TO OFF THE MID ATLANTIC COAST BY 11/12Z. ON THE HEELS OF THIS LEAD SYSTEM…A NEGATIVELY TILTED SHORT-WAVE TROUGH WILL PIVOT FROM THE CNTRL PLAINS NEWD INTO THE UPPER MIDWEST.

AT THE SURFACE…A LEE CYCLONE WILL DEEPEN OVER THE CNTRL HIGH PLAINS WHILE A SECONDARY LOW DEVELOPS FROM CNTRL SD TO THE RED RIVER VALLEY OF ND/MN. THE LEE CYCLOGENESIS WILL PROMOTE THE STRENGTHENING OF A SLY LLJ OVER THE CNTRL/SRN PLAINS…WHICH IN TURN WILL ENHANCE THE POLEWARD FLUX OF HEAT AND MOISTURE…AND THE NWD DEVELOPMENT OF A WARM FRONT THROUGH THE LOWER MO AND MID MS VALLEYS. MEANWHILE…A DRYLINE WILL BECOME ESTABLISHED BY AFTERNOON FROM THE WARM-FRONTAL SEGMENT OVER THE MID MO VALLEY SSWWD THROUGH CNTRL KS INTO W-CNTRL TX. FARTHER TO THE E…A COLD FRONT WILL ADVANCE EWD THROUGH THE NERN STATES.

…CNTRL PLAINS INTO MID MS VALLEY THIS AFTERNOON INTO TONIGHT…

DESPITE THE TENDENCY FOR MIDLEVEL HEIGHT RISES ON THE LARGE-SCALE…THE GLANCING INFLUENCE OF A SHORT-WAVE TROUGH PIVOTING NEWD THROUGH THE MID MO VALLEY COUPLED WITH LOWER-TROPOSPHERIC WAA MAY BE SUFFICIENT TO INITIATE ISOLATED TO WIDELY SCATTERED TSTMS THIS AFTERNOON. THE MOST LIKELY LOCATION FOR SURFACE-BASED STORM DEVELOPMENT APPEARS TO BE NEAR THE DRYLINE-WARM FRONT TRIPLE POINT OVER NERN KS WHERE LOW-LEVEL CONVERGENCE IS MAXIMIZED. OTHER STORMS WILL BE POSSIBLE FARTHER TO THE NORTH ALONG THE DRYLINE/WEAK FRONT OVER ERN NEB/WRN IA…AS WELL AS FARTHER TO THE S ALONG THE DRYLINE OVER S-CNTRL KS.

CONSIDERABLE VARIABILITY EXISTS IN NEAR-TERM MODEL GUIDANCE WITH REGARD TO THE DEGREE OF BOUNDARY LAYER MOISTURE AND RESULTANT INSTABILITY DEVELOPING WITHIN THE NWD-EXPANDING WARM SECTOR. IN GENERAL…IT APPEARS THAT WITH DEEPER MIXING…WARM SECTOR DEWPOINTS SHOULD CLIMB AT LEAST INTO THE LOW 60S NWD THROUGH ERN KS AND CNTRL/SRN MO…WHICH WHEN COUPLED WITH STEEP LOW TO MIDLEVEL LAPSE RATES…WILL YIELD AFTERNOON MLCAPE VALUES OF 1500-2500 J/KG. THIS INSTABILITY WILL ALIGN WITH WIND PROFILES WHICH EXHIBIT PRONOUNCED VEERING WITH HEIGHT WITH 40-50+ KT OF EFFECTIVE BULK SHEAR. AS SUCH…THE ENVIRONMENT WILL BE QUITE FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE HAIL. THE MAGNITUDE OF TORNADO THREAT WILL BE DEPENDENT ON LOW-LEVEL MOISTURE QUALITY /AND THE RESULTANT EFFECT ON LCL HEIGHT/ AS WELL AS STORM LOCATION RELATIVE TO THE WARM FRONT LOCATION WHERE LOW-LEVEL SHEAR IS MAXIMIZED.

ADDITIONAL TSTMS /LIKELY SLIGHTLY ELEVATED/ ARE EXPECTED THIS EVENING INTO TONIGHT OVER PARTS OF NRN KS/SRN NEB IN THE EXIT REGION OF A NOCTURNALLY STRENGTHENING LLJ. GIVEN THE PRESENCE OF MODERATE INSTABILITY AND AMPLE CLOUD-BEARING-LAYER SHEAR…LARGE HAIL WILL BE POSSIBLE THE STRONGEST STORMS.

…SRN OH VALLEY INTO THE CNTRL APPALACHIANS THIS AFTERNOON/EVENING…

WIDELY SCATTERED TSTMS ARE ONGOING THIS MORNING OWING TO THE INTERACTION OF THE LEAD SHORT-WAVE TROUGH MENTIONED IN THE SYNOPSIS WITH A MOIST AND AT LEAST MARGINALLY UNSTABLE AIR MASS. CORRIDORS OF STRONGER HEATING TO THE WEST OF A DENSER CLOUD BAND CURRENTLY SITUATED OVER THE CUMBERLAND PLATEAU TO ALONG THE APPALACHIANS SHOULD SUPPORT FURTHER AIR MASS DESTABILIZATION THIS AFTERNOON WITH MLCAPE VALUES OF 500-1000 J/KG. WHEN COUPLED WITH THE CONTINUED ENEWD ADVANCEMENT OF THE SHORT-WAVE TROUGH AND 35-40 KT OF WSWLY DEEP-LAYER SPEED SHEAR…THE SETUP WILL SUPPORT SOME STORM ORGANIZATION WITH A RISK FOR LOCALLY DAMAGING WIND GUSTS AND ISOLATED OCCURRENCES OF SEVERE HAIL INTO THIS EVENING.

…MID ATLANTIC STATES THIS AFTERNOON/EVENING…

WIDELY SCATTERED TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG/AHEAD OF THE COLD FRONT AND DEVELOPING LEE TROUGH WITHIN A MOIST AND AT LEAST MARGINALLY UNSTABLE ENVIRONMENT WITH MLCAPE OF AROUND 500 J/KG. THE DOWNWARD MOMENTUM TRANSFER OF RELATIVELY STRONG /35-40 KT/ FLOW IN THE 850-700-MB LAYER MAY TRANSLATE TO ISOLATED STRONG SURFACE WIND GUSTS WITH ANY INTENSE/LONGER-LIVED STORMS.

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