Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 200358
Area Forecast Discussion
National Weather Service Mount Holly NJ
1158 PM EDT TUE JUL 19 2016
High pressure will remain over the region through Friday. A cold
front may move into the area and dissipate Friday night into
Saturday. Strong high pressure then re-establishes itself into
next week, but another cold front will slowly approach from the
northwest late in the weekend.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
1150 PM...Grid update coming out shortly to increase coverage of
showers and storms across eastern MD, DE and southern NJ during
the overnight. Added enhanced wording for damaging winds and large
hail in Delmarva zones. An upper shortwave trough can be seen
moving southeastward thru the DC area with another strong one
digging in behind it near the the OH-PA border. These impulses
will provide the lift for convection across our southern zones.
SPC mesoanalysis shows a moderate amount of instability with near
surface-based CAPE of 1500-2000 J/kg from the DE Bay region
southward. Large hail and damaging winds will both be threats.
HWO already updated to account for threat. The HRRR has a decent
handle on the coverage and location of these storms. Expect the
storms that are currently over southern and eastern MD to move
eastward into DE and far southern NJ overnight and then across our
offshore waters by early morning.
Dry air will continue to filter into our region from the
northwest and north overnight. We are anticipating a partly cloudy
There will be some lingering low level moisture in our southern
counties. A mid level short wave trough dropping over our region
during the night will continue to trigger scattered showers and
isolated thunderstorms in our Delmarva counties and on the
adjacent coastal waters.
The wind should remain relatively light. Minimum temperatures
should be in the 50s up north and in the 60s elsewhere.
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
The mid-level trof axis moves off the eastern seaboard allowing
surface high pressure to build across much of the forecast area.
Temperatures tomorrow look to be the coolest of the week with mid
70s to mid 80s expected. The heat is on thereafter.
Winds won`t be as gusty tomorrow and will go southwest during the
We will keep very small POPs in the forecast across southern
Delaware during the morning hours.
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Sfc high pres will be over the area thru Fri and there will
likely be few clouds. However, conds will be genly pleasant but
withe increasing humidity by Fri. Aloft, a large and strong h5
ridge will be parked over the mid-section of the country and will
gradually shift a bit ewd. A cdfnt will move acrs the region later
Fri aftn into Fri eve and bring probably the best chc of any
precip in the next 7 days.
There is still some uncertainty as to how much of the heat
associated with this ridge we get and when. Latest guid now
indicates the peak of the heat will be Sun and Mon, and the GFS
continues to be the hottest of the mdls and got even hotter with
its 12Z run. The ECMWF, which trended cooler last night has gotten
hotter again. Some for of heat headlines may be needed over the
weekend or into next week. The CMC a bit cooler.
Temps look to be well into the 90s Fri-Mon, with dewpoints
becoming worse by Sun and Mon. There is always the chc of some
diurnal convection in a humid ams, but the guid differs on its
extent especially around Mon.
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
VFR conditions are expected through the TAF period under a partly
cloudy sky. One exception may be some MVFR visibility restrictions
around KMIV near daybreak on Wednesday.
Wind speeds are forecast to be less than 10 knots. The direction
should favor the northwest to northeast overnight, veering toward
the southeast to southwest on Wednesday.
Wed night through Thu...VFR. High pressure. High confidence.
Fri...Mainly VFR. However, shra/tsra psbl with lcl mvfr and psbl
ifr late Fri aftn into Fri night. Moderate to high confidence.
Sat through Sun. Mainly VFR. High pressure. High confidence. A
slight chc of diurnal tsra n and w on sun aftn.
Tonight...We are watching strong storms developing over eastern MD
late this evening. These storms may pose a threat to mariners
(locally strong winds and higher seas as well as lightning) in
the DE Bay overnight and our southern coastal waters toward early
morning as they move eastward. Otherwise, winds and seas will
remain below Small Craft Advisory criteria. N winds will become NE
overnight. As they veer NE, they could gust into the 15 to 20 kt
Wednesday...Winds and seas are not expected to reach SCA
criteria. The NE winds could continue in the 15 to 20 kt range in
the morning hours. They are expected and become more easterly in
Thu and Fri....Predominately sub-SCA conditions in S-SW flow.
However, there is a chance some wind gusts near 25 knots on Fri,
as well as increasing seas in advance of a cdfnt.
Sat and Sun...Brief elevated wind/seas are psbl early Sat before
subsiding to below SCA for the remainder of the pd.
RIP CURRENTS... The risk for the formation of dangerous rip
currents on Wednesday will be low at the DE and NJ beaches, but
very localized moderate rips are possible along the NJ coast.
We have had some reports of upwelling along the coast, where
temperatures have dropped into the low 60s.