730
FXUS61 KPHI 140330
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1130 PM EDT Mon May 13 2024

.SYNOPSIS...
High pressure slowly moves offshore overnight into Tuesday.
Unsettled weather returns later Tuesday and continues through
the middle of the week with a slow moving low pressure system.
After brief ridging towards the end of the week, more unsettled
weather returns for the weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
At 1100 pm...winds across the region were light south or calm.
Temperatures were mainly in the 50s. Outside of some higher
level clouds and maybe some fog, the overnight is setting up to
be fairly benign.

High pressure centered off the Delmarva Peninsula and Mid-
Atlantic coast will slowly build out to sea overnight through
Tuesday. A warm front will develop out ahead of an area of low
pressure organizing and developing over the Midwest, and that
warm front will lift into the region late in the day Tuesday.

Clouds will increase and thicken overnight and into the pre-
dawn hours of Tuesday as a warm front develops out ahead of the
low over the Midwest and lifts towards the East Coast.

Low pressure will lift into the Great Lakes and Ohio Valley, and the
warm front lifts into the region on Tuesday. This system will also
tap into moisture over the Gulf Coast states, and clouds and that
moisture will spread into the region throughout the day. Although
scattered showers are possible throughout the day, the bulk of the
activity will hold off until closer to sunset, and mainly for the
far western zones.

Lows tonight will drop into the 50s, and then highs on Tuesday will
be warmer than today, topping off in the mid to upper 70s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Widespread showers return to the region Tuesday night as height
falls and PVA will amplify lift across the forecast area.
Moisture coming from the Appalachians will move through the
region and provide a steady dose of showers late Tuesday
evening through Wednesday. QPF forecast remains largely
unchanged with most locations forecast to see around 0.75
inches of rain from Tuesday evening through Wednesday (higher
totals of 1-1.25 inches possible closer to the coast) with the
bulk coming in the early Wednesday-Wednesday morning time frame.
CAPE still looks relatively weak so while a few rumbles of
thunder may occur, its a low (<15%) chance.

As the low pressure system starts moving out of the region later
on Wednesday, lingering showers should continue into the
afternoon before drier air starts moving into the area. However
the low doesn`t move out quickly so we`ll have the potential to
see showers well into the evening.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Heading towards the end of the week, Thursday should be a
mostly quiet day as an upper level ridge starts to build into
the region. Again there are still strong timing differences
between the EC ensembles and the GFS ensembles with respect to
the speed of the systems. The GFS and its ensembles are more
progressive and leads to a dry day on Thursday while the EC and
its ensembles are slight slower which would allow for isolated
showers to develop Thursday afternoon.

The brief break in rainfall ends heading into the weekend as
the next system starts to move into over the weekend. Guidance
still shows too much uncertainty to feel confident in details at
this point but the general consensus is that a northern stream
upper level trough will strengthen and bring showers to the
region sometime over the weekend with the most likely timing
Friday night into Saturday. If the pattern were to be more
progressive, high pressure may return on Monday but that
remains highly uncertain.

Temps in the extended from Thursday onwards should be fairly
seasonable in the mid to upper 70s for highs and lows in the
upper 50s to near 60 each night.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Tonight...VFR. Some patchy fog possible from 09Z to 12Z, but
confidence low on it occurring at any given terminal. While
dewpoint depression and winds will be low, increasing cloud
coverage will prevent much runaway radiational cooling to allow
for widespread fog development. SW winds around 10 kt this
evening, diminishing to around 5 kt. Moderate confidence.

Tuesday...VFR most of the day, then MVFR CIGs after 21Z with the
best chance west of the Delaware River. Scattered SHRA may
result in brief sub- VFR VSBYs as well. S winds 5 to 10 kt.
Moderate confidence.

Outlook...

Tuesday Night through Wednesday night...Sub-VFR conditions
expected with occasional showers.

Thursday/Friday...No significant weather expected.

Friday night/Saturday...Sub-VFR conditions possible with chances
for showers increasing.

&&

.MARINE...
Sub-Small Craft Advisory conditions expected for tonight and
Tuesday. For northern New Jersey ocean waters (ANZ450-451), S winds
will increase to 15 to 20 kt with occasional gusts as high as 25 kt
through this evening, though 25 kt gusts will not be widespread
enough nor frequent enough to warrant a SCA at this time. Otherwise,
S winds will will range from 10 to 15 kt. Winds increase for the
northern New Jersey ocean waters again Tuesday afternoon, but winds
look to remain just below SCA criteria. Seas will average 3 to 4
feet.

Outlook...

Tuesday night through Wednesday...Conditions expected to be
largely sub-SCA but winds may approach 25 knots and seas 5
feet, particularly later on Wednesday.

Wednesday night through Thursday night...SCA conditions
anticipated (40-50%) as wind gusts get near 25 kt. Significant
wave heights approach 7 feet early Thursday. Showers Wed night
then mostly fair Thursday.

Friday/Saturday...Lingering 5 foot seas possible Friday but
otherwise sub-SCA conditions expected.

&&

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

&&

$$

SYNOPSIS...AKL
NEAR TERM...Kruzdlo/MJL/MPS
SHORT TERM...AKL/Deal
LONG TERM...AKL/Deal
AVIATION...AKL/MJL/MPS
MARINE...AKL/MPS