.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
High pressure moves offshore on Tuesday, and then a cold
front
approaches from the north and west Tuesday afternoon and
evening. Return
flow behind the high will tap into tropical
moisture associated with what is currently
Hurricane Debby that
will be over the Southeast. It will be quite warm and humid
ahead of this
front, and even with increasing cloud cover during
the day, highs will climb into the 80s and around 90. Although
these temperatures are not necessarily extreme not only for this
time of the year, but for this summer in particular, increasing
low level
moisture will result in
dew points well in the low to
mid 70s. Unlike today, not expecting much in the way of
afternoon mixing that would lower those
dew points. Max heat
index values will be well in the 90s and may even come close to
100 in some spots in southern New Jersey and in Delmarva. Will
hold off on issuing a
Heat Advisory at this time, as those 100
degree
heat index values will be spotty, and maybe not even in
areas where
Heat Advisory criteria is at least 100 degrees.
A cold
front and upper
trough approach from the north and west
in the afternoon and evening. SB
CAPE values will be up around
1500 to 2000
J/kg and 0-6 km Bulk
Shear values will increase to
35 to 40
kt. PWATs will also be in excess of 2 inches. The Storm
Prediction Center has most of the region except for southern
Delmarva and extreme southeast New Jersey in a
Slight Risk (1
out of 5) for severe weather. The main threat will be strong
downbursts and damaging wind gusts.
Going into Tuesday night, that
trough will interact with
tropical
moisture associated with Debby over the Southeast, and
heavy downpours are
likely. Total
rainfall will range from 1 to
2 inches, but locally higher amounts are possible. The Weather
Prediction Center has portions of New Jersey, southeast
Pennsylvania, and northern Delaware in a Moderate Risk (3 out of
4) for Excessive
Rainfall and a
Slight Risk (2 out of 4)
elsewhere. Will go ahead and issue a
Flood Watch for areas in a
Moderate Risk for late Tuesday afternoon through Wednesday
morning.
The
front will stall out south of the region Wednesday morning.
Additional
shortwave energy passing through in the afternoon
and evening will keep chances for showers and thunderstorms in
the forecast. Cooler air sinks down into the region with highs
in the 70s.
