409
FXUS61 KPHI 201613
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1213 PM EDT Mon May 20 2024

.SYNOPSIS...
High pressure continues to build across the Mid Atlantic region
today, before shifting slightly to the south tomorrow through
Wednesday. A cold front will approach the area Wednesday night,
before slowly moving across the area on Thursday, and stalling to
our south through the weekend. High pressure builds across the
northeast states Friday into Saturday, before a couple of weather
disturbances affect the area Sunday into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 12:00pm...Visible satellite imagery now shows that the
marine stratus layer has essentially eroded over much of the
area with just some broken clouds lingering across SE PA and the
northern Delmarva. Elsewhere, skies are mostly sunny with just
some diurnal cumulus starting to bubble. Forecast otherwise
remains on track.

Previous Discussion:
High pressure continues sitting to our northeast, but the axis
remains just to the northwest of most of the region. Thus, we
continue to have an overall easterly flow, which is providing a
fresh push of marine layer clouds into the region. There can be
some patchy fog in spots, but not expecting widespread dense and
no fog advisories are anticipated. This push is weaker than
yesterday as the flow is even lighter while high pressure ridge
axis slowly settles to our southeast over time, so think morning
clouds should be more efficiently burned off today. The result
should be a mostly sunny afternoon overall. A few models are
suggesting that the ample May insolation combined with
relatively moist atmosphere may spark a few light showers, most
likely in the Poconos, so have put a few sprinkles in the
forecast up there. Highs should be near to slightly warmer than
yesterday, mostly 70s, cooler along the coast.

Tonight, with the high axis pushing further to our southeast,
winds should become more southerly. However, they remain light,
and some more late night low clouds and fog are possible. Lows
mostly in the 50s.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Overall, little changes were made to the short term period as
the mid to upper level ridge essentially lies overhead through
Tuesday night before beginning to breakdown and shift offshore
on Wednesday. Down at the surface, broad high pressure over New
England will expand southwest while becoming elongated into the
southern Appalachian region. The high will sink south of the
region on Tuesday and eventually settle offshore the Mid-
Atlantic coast by Tuesday night into Wednesday. This will yield
dry conditions throughout the period.

It is possible a round of fog may develop on Tuesday night, but
confidence in this is less than Monday night so have left the
mention out of this out of the forecast for now.

In terms of temperatures, it is looking like we will return
close to normal with respect to low temps both nights with lows
generally in the 50s to around 60 degrees. For high
temperatures, it is likely that much of the area will range
about 5-10 degrees above normal on Tuesday and as much as 10-15
degrees above normal on Wednesday. Meaning high temps will top
out 80s both days as southerly flow ushers warmer air north. The
exception will be for our coastal locales where a sea breeze
circulation looks to develop each day. Given how cold the water
temperatures are, there is potential for the sea breeze to
develop early enough in the day, that the sea breeze reaches far
enough inland that highs for most, if not all, of the coastal
plain could be slightly lower than what is forecast.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Unsettled weather will continue into Thursday as a cold font
will move across the Mid Atlantic region and east coast. There
will be some instability across the area, so there will be a
chance of thunderstorms as well.

The cold front is expected to stall to the south Friday and
into the weekend. As it does so, several disturbances are
expected to move along the boundary, and may pass close enough
to bring showers to the area Friday through the weekend.

&&

.AVIATION /16Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

This Afternoon...CIGs are mostly VFR/MVFR as of this early
afternoon. As marine layer continues to erode, expect all
terminals to regain VFR CIGs by 18-19Z. Light and variable winds
should ultimately settle out of the south-southeast around 5 kt.
High confidence.

Tonight...VFR to start but IFR cigs/vsby possible late as low
clouds/fog may redevelop. Winds light southerly. Low
confidence.

Outlook...

Tuesday-Wednesday...Generally VFR except possible lower
conditions around daybreak.

Wednesday night-Thursday night...Sub-VFR conditions possible
with a chance of showers and thunderstorms.

Friday...VFR conditions expected.

&&

.MARINE...
No marine headlines are in effect through tonight. Expect seas
generally around 3 to 4 feet with gusts up to 20 kts.

Outlook...

Monday night through Friday...No marine headlines are expected.
Fair weather expected through Wednesday night with a chance for
thunderstorms on Thursday into Thursday night. Fair weather is
expected to return on Friday.Sub Small Craft Advisory
conditions over the waters through tonight. Expect seas
generally around 3 to 4 feet with gusts up to 20 kts.

Rip Currents...

A prolonged period of NE to E winds at 10 to 15 mph during the
day and 5 to 10 mph at night will continue through today. Along
with 3 to 4 ft seas, this will result in a MODERATE risk for
the development of dangerous and life threatening rip currents
today at New Jersey and Delaware beaches. The rip current risk
may be low for most of the day for southern New Jersey beaches.

By Tuesday, the winds will be veering to more of a southerly
direction at 10 to 15 mph which will reduce the onshore
component at most beaches. However we`ll also be heading closer
to the Full Moon on the 23rd so for this reason expect that most
of our beaches will continue to see a MODERATE risk for the
development of dangerous rip currents.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...RCM
NEAR TERM...DeSilva/RCM
SHORT TERM...Robertson
LONG TERM...Robertson
AVIATION...DeSilva/RCM/Robertson
MARINE...DeSilva/RCM