SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Tue May 04 2021 Valid 041200Z - 051200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM CENTRAL LOUISIANA EASTWARD THROUGH MISSISSIPPI/ALABAMA AND INTO ADJACENT PARTS OF TENNESSEE AND WESTERN GEORGIA... ...SUMMARY... Widespread strong to severe thunderstorm development is probable today across the Deep South. The primary risk will be scattered severe gusts resulting in wind damage and an accompanying risk for a few tornadoes. ...Synopsis... A mid-level shortwave trough initially near the OK/AR border this morning, will move east and reach the central/southern Appalachians by early Wednesday morning. An effective cold front modulated by convection at the start of the period, is forecast to move east across the lower MS Valley and OH Valley/Mid-South during the day. A weak surface low is forecast to migrate northeastward from AR to the lower Great Lakes. ...Southeast and northern Gulf Coast... A couple of thunderstorm clusters/MCSs are forecast this morning across the OH Valley south-southwestward into the lower MS Valley and east TX near the aforementioned surface boundary. The risk for damaging gusts will probably accompany one or more of these thunderstorm clusters given moderate instability and a moisture-rich airmass. Model guidance varies considerably regarding the evolution of a probable thunderstorm cluster located over KY/TN during the morning. A portion of this convective band may continue into northern AL/GA and be aided by the nose of a 35-kt LLJ situated over MS at daybreak. It is less clear if storms rejuvenate farther east near the Cumberland Gap and parts of VA/NC during the day or if the focus for thunderstorms is shunted farther south over GA/Carolinas. Given a very moist and very unstable airmass sampled Monday night along the northern Gulf Coast (reference the 00 UTC Slidell, LA raob featuring an 18 g/kg mean mixing ratio and 3500 J/kg MLCAPE), it is plausible a couple of organized thunderstorm bands will develop coincident with the diurnal heating cycle. The m-shaped hodographs due in part to the positive-tilt character of the mid-level trough, in combination with high PW, will favor upscale growth with developing storms. It appears a swath of damaging gusts is most probable from parts of MS east through parts of AL. A gradual diminishing in thunderstorm intensity is expected by the mid evening hours. ...OH Valley and Mid-Atlantic states... Isolated to scattered thunderstorms are forecast to develop during the day on the northern periphery of a moist/unstable sector. Relatively large uncertainty exists with convection potentially limiting the degree of destabilization, especially across parts of the OH Valley during the day. Nonetheless, it seems an isolated risk for damaging gusts and perhaps hail may accompany the stronger storms before this activity weakens during the evening. ..Smith/Lyons.. 05/04/2021
There’s more click here.