Twin States Weather Blog

New Mesoscale Discussion

* SPC has issued a "Mesoscale Discussion" -- these are technical but informal discussions of the expected progression of impending weather threats...

* This one includes most of our west Alabama counties...

* Here's the discussion that accompanies the graphic above (you may click that image for a larger version):

SLOW INCREASE IN CONVECTIVE DEVELOPMENT IS ALREADY ONGOING. THIS SHOULD INTENSIFY FURTHER THIS AFTERNOON. TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT...AND THE POSSIBILITY OF A WW.

INITIAL SOUTHERN BRANCH IMPULSE CONTINUES TO LIFT NORTHEASTWARD THROUGH THE UPPER TENNESSEE VALLEY. 50+ KT 500 MB JET STREAK SEEMS TO BE ACCOMPANYING THIS FEATURE...AND MAIN CONVECTIVE DEVELOPMENT ASSOCIATED WITH STRONGER MID-LEVEL FORCING IS BEGINNING TO SHIFT TOWARD THE UPPER OHIO VALLEY/NORTH CENTRAL APPALACHIANS. HOWEVER...IN WAKE OF THIS FEATURE...AND AHEAD OF LOWER MISSISSIPPI VALLEY SHORT WAVE TROUGH...CONFLUENT LOW-LEVEL REGIME MAY BECOME FOCUS FOR INCREASING THUNDERSTORM ACTIVITY INTO THE 19-20Z (2-3 PM) TIME FRAME.

MOIST BOUNDARY LAYER FROM THE WESTERN SLOPES OF THE SOUTHERN APPALACHIANS INTO NORTHERN ALABAMA IS DEEPENING WITH INSOLATION. AS TEMPERATURES APPROACH THE LOWER 80S...MIXED LAYER CAPE IS EXPECTED TO EXCEED 1000 J/KG. THIS SHOULD BE SUFFICIENT FOR VIGOROUS UPDRAFTS IN FAVORABLY SHEARED ENVIRONMENT FOR MID-LEVEL UPDRAFT ROTATION. LARGE HAIL MAY BE PRIMARY SEVERE THREAT.

posted by WTOK Weather Staff @ 12:32 PM