We’ll start off the discussion with the latest mesoscale update from NWS Nashville:
“.MESOSCALE UPDATE… RAIN COOLED AIR HAS MOVED ACROSS A GOOD PART OF WESTERN MIDDLE TENNESSEE THIS MORNING DELAYING SEVERE STORM THREAT FOR SEVERAL HOURS IN THIS AREA. SOUTHERN AND SOUTHEASTERN MIDDLE TENNESSEE…CLOSER TO THE ALABAMA BORDER HAS WARMED NICELY THROUGH THE MORNING BEING SOUTH OF THE COLD POOL WITH TEMPERATURES IN THE MIDDLE 70S. 850 MBAR JET ON THE ORDER OF 50-60 KNOTS HAS REMAINED INSITU LAST SEVERAL HOURS FROM CENTRAL MISSISSIPPI NORTHEASTWARD THROUGH MIDDLE TENNESSEE. AIR MASS ACROSS SOUTHERN MIDDLE TENNESSEE WILL CONTINUE TO DESTABILIZE OVER THE NEXT FEW HOURS SO WILL NEED TO KEEP REALLY CLOSE TABS ON THIS AREA FOR THE POTENTIAL FOR MORE DISCRETE AND RAPID DEVELOPMENT IN THE FORM OF SUPERCELLS. THIS MAY TAKE A COUPLE OF HOURS SINCE CAP WILL HAVE TO BE BROKEN. AS WE GET INTO THE AFTERNOON HOURS EXPECT TO SEE ACTIVITY PICK UP BACK TO OUR WEST CLOSER TO THE TENNESSEE RIVER AND TAKE ON MORE OF A LINEAR OR SQUALL LINE APPEARANCE WESTERN MIDDLE TENNESSEE DOWN INTO NORTHEAST MISSISSIPPI. IN ADDITION A FLOOD THREAT EXIST FOR ALL OF MIDDLE TENNESSEE THROUGH 11 PM TONIGHT. THREE TO FOUR INCH RAINFALL AMOUNTS HAVE ALREADY FALLEN ALONG AND 40 MILES SOUTH OF INTERSTATE 40 FROM FAIRVIEW TO THE TENNESSEE RIVER.”
Highlights from the conference call…
– This event has the opportunity to be locally significant.
– There has been flash flooding to our west across Williamson, Maury, and Lewis counties. That is expected to continue throughout the day as we expect up to 2-4 additional inches of rain.
– All modes of severe weather are possible
– The greatest chance of severe weather will be situated across areas south of I-40, as this is where the greatest tornado chance will be. Significant and long-track tornadoes are possible this afternoon/evening.
– Perhaps the greatest question most of the weather geeks have is what will the rain this morning do to our atmsophere? Quite typically, this situation serves as a scrubber or a cleanser and “cleanses” our atmosphere. However, this is not the case this time. The rain has produced what meteorologists call a “thermal moisture boundary”. Essentially it is a cold pool that serves as a highway of sorts for supercell thunderstorms. Often they latch on this boundary and strengthen explosively. Right now, this boundary exists along the Bedford/Rutherford Co line, and back west through Maury Co. NWS Nashville will be watching this area CLOSELY once storms begin firing back to the southwest. For example, the Mayflower, AR tornado was a result of a storm interacting with this type of boundary. The atmosphere was a lot more conducive for strong tornadoes across S Arkansas, but this tornado formed across N sections of the state.
– Best chance for severe weather across the area will be late afternoon into the early evening.
– Continue to spread the word about the storm chances for today. Emphasis on “Don’t be scared…be prepared.”.
More info as it becomes available.