Valid 201300Z – 211200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE OH VALLEY INTO WESTERN NEW ENGLAND AND OVER THE DEEP SOUTH…
Isolated strong to severe storms capable of producing mainly wind
damage may occur across parts of the Ohio Valley into the
Mid-Atlantic and Northeast States. Isolated strong to severe storms
are also possible across portions of the Deep South.
…Ohio Valley/Northeast States/western New England…
A shortwave trough over the Midwest will phase with an additional
trough over northern Ontario, while a polar jet otherwise
strengthens over the Lower Great Lakes and Northeast States. At the
surface, primary wind shift will progress across the Ohio Valley to
a position from western NY-central OH-western KY by early afternoon.
Dew points have steadily risen into the mid 50s-60F across the warm
sector as far north as western PA early this morning and this air
mass should advance into NY prior to frontal passage. Very strong
wind fields will overspread the OH Valley into New England ahead of
the trough with LLJ forecast to be on the order of 70kt across
western PA at the beginning of the period. While forecast soundings
do not exhibit appreciable instability, there is some concern that
any convection that develops along/ahead of the wind shift may
produce locally severe wind gusts given the strength of the
deep-layer wind field.
A southern-stream shortwave trough will continue to progress
northeastward from east-central/northeast Texas toward the Tennessee
Valley by evening. Ongoing scattered convection will continue to
effectively augment a southwest/northeast-extending front, which
will advance southeastward across the region through tonight.
Low-level convergence will tend to remain weak while overall
instability will be tempered amidst moist-adiabatic lapse rates.
Nonetheless, wind profiles are strong and a few stronger storms
could materialize particularly this afternoon. Localized wind damage
appears to the most probable risk.