711
FXUS61 KPHI 081301
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
901 AM EDT Mon Jul 8 2024

.SYNOPSIS...
A weak cold front approaches our region Tuesday into Wednesday.
The remnant low of Beryl will track to the northwest of our
region Wednesday into Thursday. Another front gets close to our
region Friday into Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Based on visible sat pix and cams, some areas have seen the
thicker fog over the ocean advect in across Atlantic and Cape
May counties. But this fog is now evaporating. The fog remains
dense over the upwelled nearshore ocean waters.

For the rest of Monday, hot and humid conditions persist across the
region with no discernible change from the day prior. Morning clouds
and areas of fog will give way to a mix of sun and clouds
during the afternoon. A slight chance of a shower/storm is
possible mainly north and west of the I95 corridor, where there
is some forcing near a washed out, retreating boundary. High
temps will be in the low to mid 90s across interior locations
with 80s in the Poconos and along the coast. The biggest change
for Monday is that dew points are forecast to be at least a few
degrees higher in the upper 60s to mid 70s. The combination of
these T/Td`s yield heat indicies around 98-102 degrees across
much of the area. Heat Advisories remain in effect for all of
our NJ counties except Cape May, all of our PA counties except
Carbon/Monroe, and New Castle County in Delaware beginning at 10
AM.

Not much relief Monday night with increasing clouds helping keep
temperatures warm even at night with lows only cooling to the low to
mid 70s for most and near upper 70s for the Philly metro. Dew points
remaining in the low to mid 70s as well will lead to yet another
muggy night with a chance for some patchy fog.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
The big story with this period is the approach of Beryl, primarily
Wednesday into Thursday, resulting in an increase in thunderstorm
chances, particularly north and west of the fall line. Another
concern is the continued hot and humid conditions especially
Tuesday, but possibly continuing through Thursday.

Tuesday...Dangerously hot and humid conditions continue with most of
the region getting in to the 90s. No changes at this time to the
heat advisory, but will be watching the dew point trends closely as
portions of Delmarva could also get close to heat advisory criteria.
As for storm chances, as mentioned by the previous shift, the lack
of synoptic scale forcing should keep thunderstorm coverage limited,
but any storms that develop will be capable of heavy rain thanks to
high precipitable water values and a deep warm cloud layer.

Wednesday into Thursday...The remnant low of Beryl still looks to
track northwest of our region, keeping the strongest forcing
generally northwest of our region as well. That being said, still
looks like we will have considerable coverage of storms particularly
north and west of the fall line. The highest precipitable water
values of the week (and possibly close to record maxes for this time
of year) are expected during this period as well. The good news is
that storm motions should be relatively quick, which will somewhat
limit the flooding threat unless we see training storms.

As for the risk of dangerous heat, while we have high confidence in
humidity levels, clouds could limit heating if it comes in early
enough on Wednesday. Thus for now, chose not to extend the heat
advisory into Wednesday, but will be watching this period closely if
that will be needed for future updates.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
Overview: Chances for thunderstorms with heavy rain continue Friday
into Saturday. Sunday and beyond could see  thunderstorm
development, but expect it to be more isolated than coverage we
could see Friday into Saturday.

Details:

Friday into Saturday...Remnant low of Beryl should be well north and
weakening/filling by the day time on Friday. However, the previously
mentioned cold front will be stalling near or over our region. In
the mid and upper levels, a trailing trough will be approaching our
region in this period. The biggest concern I have with this period
of the forecast is the potential for heavy rain. Not only will
precipitable water values remain high (as there will be minimal dry
air advection between Thursday and Friday), but this set up has many
similarities to a Maddox Synoptic heavy rain event. The front
should be stationary (or very slow moving), it has a favored
orientation for these types of events, and the winds from 700 to 300
mb should be nearly parallel to the front. This could set the stage
for training storms capable of heavy downpours.

The main question remaining in terms of the threat specifically to
our region is how close the front will get before stalling. Some of
the latest deterministic guidance shows it stalling further west,
limiting the risk in our region. However, this is a relatively new
trend over the past few model runs, and there remains some models
depicting the front stalling over our region.

Saturday night into Sunday...Front should dissipate, and flow aloft
should become mostly zonal. While I can`t rule out some additional
storm development, by this point it is unlikely we will see
widespread thunderstorm coverage. Another mid an upper level trough
could approach as early as late Sunday, but confidence in the timing
of that feature is low at this time.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today...Some IFR/LIFR visibilities and/or ceilings at KACY
through mid-morning, otherwise VFR expected. SE winds around
5-10 kt. A very small chance of a thunderstorm down to about the
I95 terminals, but coverage is too low at this time to include
in the TAFs. Low confidence in any storm development, but high
confidence otherwise.

Monday night...VFR with light S-SSE winds. Some patchy fog could
develop, especially closer to the coast.

Outlook...

Tuesday through Friday...Periods of MVFR or lower conditions with
thunderstorms.

&&

.MARINE...
The Marine Dense Fog Advisory remains in effect for our ocean
waters and lower Delaware Bay through 1 PM, but with the light
winds, we would not be surprised if it`s needed through the
remainder of the day. Outside of the fog, tranquil conditions
are expected with south-southeasterly winds around 5-10 kts and
seas 2-3 feet.

Both the fog and tranquil conditions outside the fog should
persist through tonight.

Tuesday through Wednesday...Winds and seas should stay below SCA
criteria. Locally gusty winds in the vicinity of any thunderstorms.

Wednesday night through Friday...Southerly winds increase and seas
will subsequently increase as well. Thus could see conditions right
around SCA criteria especially on the Atlantic coastal waters
through this period.

Rip Currents...
For Monday, winds will remain east to southeast 5-10 mph, while
waves on the ocean will be around 2 feet with a 5-8 second
period. This will lead to surf height waves of 1-2 feet. There
for the Rip Current Risk will be LOW on Monday.

On Tuesday, winds shift more out of the south and increase to
10-15 mph, while the waves on the ocean will increase to 2-3
feet with a 5-7 second period. This will lead to surf heights
waves of 1-3 feet. The Rip Current Risk will be MODERATE for the
Ocean, Atlantic, and Cape May shore and LOW for Monmouth, NJ
and Sussex, DE beaches.

For specific beach forecasts, visit weather.gov/beach/phi

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT Tuesday for PAZ060>062-070-071-
     101>106.
NJ...Heat Advisory until 8 PM EDT Tuesday for NJZ001-007>010-012-
     013-015>022-027.
DE...Heat Advisory until 8 PM EDT Tuesday for DEZ001.
MD...None.
MARINE...Dense Fog Advisory until 1 PM EDT this afternoon for ANZ431-
     450>455.

&&

$$

SYNOPSIS...Gorse/Johnson
NEAR TERM...Kruzdlo/MJL
SHORT TERM...Johnson
LONG TERM...Johnson
AVIATION...Kruzdlo/Johnson/MJL
MARINE...Kruzdlo/Johnson/MJL