MD 1697 CONCERNING TORNADO WATCH 491… FOR PARTS OF NORTHERN FLORIDA AND THE FLORIDA PANHANDLE AND ADJACENT SOUTHWESTERN GEORGIA
Mesoscale Discussion 1697
NWS Storm Prediction Center Norman OK
0208 PM CDT Wed Sep 16 2020
Areas affected...Parts of northern Florida and the Florida Panhandle
and adjacent southwestern Georgia
Concerning...Tornado Watch 491...
Valid 161908Z - 162115Z
The severe weather threat for Tornado Watch 491 continues.
SUMMARY...At least isolated thunderstorms capable of producing
tornadoes remain possible through 7 PM EDT. It is unclear how much
longer an appreciable risk for tornadoes will continue thereafter,
but it is possible that a new tornado watch may be needed for this
evening across parts of southern Georgia and northern Florida.
DISCUSSION...Substantive boundary-layer warming has now occurred as
far north as the southern tier counties of Georgia (including the
Valdosta, Thomasville and Bainbridge areas), where surface dew
points have increased into the mid 70s F. This is focused along a
remnant frontal zone, where near surface vertical shear may now be
maximized, near the eastern periphery of the core of stronger
southerly 850 mb flow.
There may be considerable further weakening of this flow into early
evening, with little eastward progression, as the low-level
circulation center of Sally only very slowly migrates
east-northeastward near the western Alabama/Florida state border
vicinity. However, despite these trends, the environment remains
potentially conducive to occasionally strengthening low-level
mesocyclones within and ahead of bands of convection to the east of
the circulation center. This may be accompanied by a risk for
tornadoes, particularly in any rapidly intensifying storms aided by
increasing inflow of boundary-layer CAPE on the order of 1000-2000
J/kg, in the peak late afternoon warmth.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 31168491 31208470 31458351 30808292 29998360 30088407
30028477 30488471 30978482 31168491