Mount Holly's latest AFD
KEY MESSAGE 3...Widespread rain with potentially a few
thunderstorms moves in for the afternoon hours on Wednesday,
continuing into Thursday morning.
The upper-level pattern is forecast to become rather amplified
through this week. A strong upper-level trough axis shifts to
our east Tuesday as high pressure will also be shifting
offshore. Another upper-level trough then moves over the Eastern
US Wednesday into Thursday before lifting out Friday into
Saturday. Guidance seems to be trending toward the earlier
ECMWF`s idea that the incoming trough will close off either over
our area or just off to the east. The timing and location of
where the cutoff occurs will determine when things dry out. If
the trough cuts off over our area, showers could linger into
Thursday. If it cuts off just to the east, showers should move
out by Thursday, giving way to a nice weekend (more on that in
Key Message 3). Regardless of how this transpires, a round of
widespread rain is expected with as the incoming trough and cold
front arrive.
As the aforementioned upper-level trough moves into the region
Wednesday, low-level warm air advection will increase ahead of
it as the low to mid level flow also increases. This will result
in an increase in forcing for ascent, and some instability
should develop ahead of the main forcing. A warm front should
also lift across our area Wednesday with some ascent associated
with it. As a result, showers should increase Wednesday from
west to east, especially in the afternoon with forcing peaking
Wednesday night as the cold front arrives. The amount of
destabilization is more uncertain, however guidance does show
some instability which should be enough to support at least a
few thunderstorms. The intensity of any thunderstorms however
will depend on the magnitude of the instability and shear.
However, guidance this morning does not show much in terms of
instability, with shear looking rather meager as well. This
would result in a low to zero severe threat, with better
kinematics well off to our west.
The main forcing should shift to our east and northeast
Thursday with the bulk of the showers ending. However, if the
closed low scenario ends up happening, then the core of the cold
air aloft with this slides overhead and this could result in
additional shower development on Thursday before the system
departs our region. Rainfall amounts are trending to be right
around a half inch or so.
