Probability of Watch Issuance...80 percent
SUMMARY...The tornado threat is expected to gradually increase into
this afternoon. Tornado Watch issuance is likely by 16Z.
DISCUSSION...At 1445Z, T.D. Fred is still moving northeastward near
the OH/WV border northeast of Parkersburg, WV. A warm front extends
east-northeast from the cyclone across southern PA, while a surface
confluence axis is noted extending from southwest PA into central
VA. Rich low-level moisture will continue to stream northward across
PA in conjunction with the warm front this afternoon, with some
breaks in the clouds allowing for some modest destabilization from
central PA southward into MD/northern VA.
Convection will likely increase in coverage with time near/north of
the warm front, with more scattered convection possible along/east
of the surface confluence axis into MD/northern VA. This afternoon,
0-1 km SRH will likely be maximized over central PA (potentially in
excess of 200 m2/s2), though somewhat enhanced SRH will also extend
southward into MD/VA where surface winds remain backed to a
southeasterly direction. Scattered supercells are likely to evolve
with time as convection matures, with an attendant threat of a few
tornadoes and isolated/scattered damaging wind gusts. Tornado Watch
issuance is likely by 16Z in response to these threats.