Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 2 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
SPC AC 151706
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1206 PM CDT Tue Sep 15 2020
Valid 161200Z - 171200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE FLORIDA
PANHANDLE...
...SUMMARY...
A few tornadoes associated with Tropical Cyclone Sally are possible
across portions of the Florida Panhandle, northern Florida,
southeastern Alabama, and southern Georgia on Wednesday.
...Synopsis...
Relatively weak flow aloft will persist across the southern half of
the CONUS on Wednesday with a weak upper ridge centered near the
Four Corners, modest troughing from the Mid MO Valley into the
southern High Plains, and another weak ridge over the Southeast.
Hurricane Sally is expected to move slowly northward/northeastward
within this weak flow environment. Current NHC forecast places the
storm onshore near the MS/AL border early Wednesday morning before
then slowly tracking northeastward through southern AL. Primary
severe weather threat during the period will be associated with
Sally (discussed in more detail below).
Farther north, strong cyclonic mid-level flow throughout the base of
a large upper trough will extend across the Canadian Prairie
Provinces through the northern Plains and Upper Great Lakes. An
embedded shortwave trough is expected to move across Ontario,
followed by an area of high pressure dropping into the northern
Plains/Upper Midwest. This evolution will push a cold front across
much of the central Plains and mid MS/OH Valleys. Buoyancy ahead of
the front will be limited by substantial mid-level dry air, but a
few lightning strikes still appear possible. Even so, overall
coverage is expected to remain less than 10 percent.
A shortwave trough (and accompanying strong mid-level flow) is
expected to move through the base of an upper low off the Pacific
Northwest coast. Strong flow aloft and ascent associated with this
shortwave will impinge on the portion of the Pacific Northwest west
of a Cascades, contributing to the potential for isolated lightning
strikes.
...Southeast/Hurricane Sally...
Strong low-level wind fields associated with Hurricane Sally will
continue to slowly spread northward/northeastward as the storm
gradually progresses inland. The lack of stronger steering flow has
resulted in a wide range of model solutions regarding the storm
speed, contributing to some uncertainty regarding the northern
extent of the tornado potential. Even so, the most favorable
parameter space will be over the FL Panhandle and perhaps into
extreme southeast AL and extreme southwest GA. Warm and moist
tropical profiles will limit instability, but the very strong
low-level kinematics will support rotation with any more persistent
updrafts. Depending on the speed of the system, this favorable
parameter could extend into southeast GA by early Thursday.
More marginal parameter space (i.e. slightly less favorable
thermodynamics and weaker low-level winds) will extend eastward and
northeastward from the center across portions of southern GA and
northern FL. More cellular storms could occur within the rain bands
surrounding the system in this area and there is a low probability
potential for a tornado or two.
..Mosier.. 09/15/2020
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
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