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The Storm Prediction Center has issued its Day One Convective Outlook and it pegs a large part of northern Alabama, northern Mississippi, northwestern Georgia and Middle Tennessee in the bullseye as a high risk area for severe weather today.
It is the basic scenario we have been painting with little change. A strong upper level trough moving in from the west. Powerful mid level winds, with 110 knot jet max at 18,000 feet moving across the region from North Texas, surface low moving east northeast from Arkansas during the morning (it is still in Texas now), warm, moist and unstable airmass south of rain cooled air mass over Tennessee and Kentucky, and a capping inversion allowing the pot to simmer for a long time before the lid is removed and the pot boils over.
The result could be a widespread outbreak of tornadoes and widespread damaging winds, especially over the high risk area. An excerpt from the outlook:
THE RESULT WILL BE FAST MOVING
TORNADIC SUPERCELLS CAPABLE OF STRONG TO VIOLENT TORNADOES. GIVEN
THE FAST STORM MOTIONS AND RELATIVELY WIDE WARM SECTOR…SOME
TORNADOES COULD BE LONG LIVED.
Here is the part of the text from the SPC Outlook that applies to us…
— AN OUTBREAK OF TORNADOES AND DAMAGING WINDS IS EXPECTED TODAY
THROUGH EVENING OVER PORTIONS OF NRN MS…NRN AL…TN AND KY. —
…LOWER MS VALLEY INTO TN/OH VALLEYS…
A COMPLICATED FORECAST SCENARIO WILL UNFOLD TODAY…BEGINNING RATHER
EARLY IN THE PERIOD OVER SRN AND ERN AR AND NRN LA. MODELS ARE IN
RELATIVELY GOOD AGREEMENT WITH THE PLACEMENT OF THE SURFACE LOW OVER
AR BETWEEN 12-15Z…THEN DEVELOPING IT NEWD ACROSS TN/KY BY 00Z.
NUMEROUS THUNDERSTORMS WILL BE ONGOING…AND SOME WILL BE
SEVERE…FROM NRN LA/SRN AR EWD ACROSS NRN MS…WRN AND MIDDLE TN
AND KY. DESPITE TIME OF DAY…PRESENCE OF RICH LOW LEVEL MOISTURE
WILL RESULT IN LITTLE CAPPING AND SURFACE BASED EFFECTIVE PARCELS.
THUS…A TORNADO AND DAMAGING WIND THREAT WILL BE PRESENT WITH THIS
ACTIVITY.
SOUTH OF THE ONGOING ACTIVITY…STRONG DAYTIME HEATING WILL OCCUR.
WITH BOUNDARY LAYER DEWPOINTS IN THE LOW 70S F…THIS WILL CREATE
STRONG TO EXTREME INSTABILITY OVER MS AND AL NWD TO THE ONGOING
CONVECTION. A CAPPING INVERSION WILL LIKELY KEEP MUCH OF THE WARM
SECTOR S OF THE EARLY STORMS CAPPED…ALLOWING A BUILD UP OF
INSTABILITY TO BE RELEASED WHEN LARGE SCALE FORCING ARRIVES DURING
THE AFTERNOON ALONG THE COLD FRONT AND ESPECIALLY NEAR THE
FRONT/OUTFLOW BOUNDARY INTERSECTION. THE RESULT WILL BE FAST MOVING
TORNADIC SUPERCELLS CAPABLE OF STRONG TO VIOLENT TORNADOES. GIVEN
THE FAST STORM MOTIONS AND RELATIVELY WIDE WARM SECTOR…SOME
TORNADOES COULD BE LONG LIVED. THE GREATEST THREAT FOR THESE TYPES
OF STORMS WILL BE OVER THE HIGH RISK AREA…OVER NRN MS AND
AL…INTO EXTREME NWRN GA AND SRN MIDDLE TN. THIS ACTIVITY WILL
PERSIST TO THE E…BUT CELLS MAY EVENTUALLY MERGE INTO MORE OF A
QLCS STRUCTURE CAPABLE OF PARTICULARLY DAMAGING WINDS AND A FEW
TORNADOES.
