975
FXUS61 KPHI 051726
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
126 PM EDT Wed Jun 5 2024

.SYNOPSIS...
An area of low pressure approaches from the northwest late today
with a warm front moving through the region this evening. A
cold front follows tomorrow crossing through the region on
Thursday into Thursday night. Heading into the weekend unsettled
weather looks to persist into early next week as several
shortwaves pivot around the upper low over southern Canada.

&&

.NEAR TERM /THROUGH TONIGHT/...
Warm front lies just southwest of the forecast area and will
continue to lift north this afternoon and into tonight and
should be north of the area by Thursday morning. The front will
be accompanied by some shortwave energy aloft which will
increase the forcing of ascent across the region. As a result,
an initial batch of showers and thunderstorms are expected to
develop and approach from the southwest and overspread the rest
of the region this evening. For most of the overnight period,
light to moderate rain (with embedded thunder) is expected,
giving way to just some spotty showers/storms by early Thursday
morning as depicted by most of the hi-res guidance.

Although mostly cloudy to overcast skies will encompass much of
the region today, a very moist airmass will be in place. Thus,
there is a fairly high chance for some thunderstorms this
afternoon into tonight. Despite limited surface heating, a
narrow corridor of SBCAPE in excess of 1000 J/kg this afternoon
will be in place across the Delmarva which will lie in close
proximity to the warm front. However, mid-level lapse rates are
weak (only near 6.5C/km) which will likely hinder development of
strong updrafts. As a result, the Storm Prediction Center has
upgraded the Eastern Shore of Maryland into a Marginal Risk
(Level 1/5) for severe weather today. The rest of the area lies
in just a general thunderstorm risk. The main threat in the
highlighted area will be damaging winds. With backed SE surface
winds near the warm front, model soundings due show some curved
hodographs in the lowest 0-3km. So while there is a non-zero
chance of a tornado, the greater potential looks to lie outside
of our area.

PWATs will also be near/in excess of 2.0 inches later this
afternoon into tonight, so heavy downpours are likely,
especially in any thunderstorm that occurs. Currently, WPC has
the western half of our forecast area highlighted within a
Marginal Risk (Level 1/4) risk for excessive rainfall. However,
flash flooding does not appear to be a threat as ground soils
are relatively dry and the storm motion is quite quick. QPF
values through tonight are forecast to be around 0.5-1.0 inches,
locally higher in thunderstorms.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
A deep upper trough will be accompanied by a nearly vertically
stacked low pressure system which will be meandering around
southern Canada and the northern Great Lakes during the period.
This will bring a cold front through by Thursday into Thursday
evening.

Guidance continues to highlight the likelihood of a concentrated
set of showers and thunderstorms moving through the region
Thursday afternoon into the evening. CSU-MLP guidance still
indicates a 5-14% chance of severe weather on Thursday with the
most likely threat being hazardous wind. Showers and
thunderstorms will cease on Thursday night as the cold front
moves offshore.

Highs will be in low/mid 80s on Thursday dependent on the
amount of clearing. Thursday night lows will be cooler in the
upper 50s to mid 60s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The long term period is forecast to be generally unsettled
through early next week. The aforementioned upper trough and low
will meander across southern Canada and the northern Great
Lakes through the weekend. As it does so, multiple shortwaves
will round through the upper trough resulting in several rounds
of showers and occasional thunderstorms through the weekend into
next week. While no singular day appears to be a washout, there
will be quite a bit of showers around, more likely north and
west with drier conditions south and east. The highest
probability of precipitation will be during the afternoon hours
as diurnal heating allows instability to be maximized.

Temperatures during this period will remain quite seasonable for
early June with a mix of 70s/80s during the day and 50s/60s at
night.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...Some lingering MVFR CIGs becoming VFR by 19Z. Another
round of lowering CIGs down to MVFR are expected later in the
day as rain showers and isolated thunderstorms move into the
region. South-southeast winds around 5-10 kt. Moderate
confidence.

Tonight...All terminals should encounter lowering CIGs and
decreasing VSBYs as heavier rain moves in this evening. Heaviest of
rain should continue through about 06-08Z, before lifting north and
east of the region. Still anticipate lower CIGs/VSBYs to persist
after rain exits. South-southwest winds around 5-10 kt. Low
confidence.

Outlook...

Thursday through Thursday night...Sub-VFR conditions probable
with showers and thunderstorms.

Friday through Saturday...Primarily VFR expected with sub-VFR
conditions possible. A chance of a shower or thunderstorm each
afternoon.

&&

.MARINE...
No marine headlines are expected through tonight. Fair weather
this morning will give way to showers and thunderstorms later
this afternoon into tonight. South-southeast winds around 10-15
kt today increasing up to 15-20 kt tonight. Localize higher
gusts up to 22-23 kt possible. Seas of 2-3 feet increasing to
3-4 feet.

Outlook...

Thursday and Thursday night...Sub SCA expected, however winds
may gust around 20+ kt on Wednesday night into Thursday. Seas
around 3-4 feet. Showers likely with a chance of thunderstorms.

Thursday night through Saturday...No marine headlines expected.
Winds generally around 10-15 kt with seas of 2-4 feet. Slight
chance of a shower or thunderstorm each afternoon.

Rip Currents...

A LOW risk for the development of rip currents is in place for
both New Jersey and Delaware beaches for today. Winds will be
on onshore from the SSE, but only around 10-15 mph with 1-2
foot waves and a 9 second period.

For Thursday, SSW winds around 10-15 mph will parallel the
shoreline for NJ and offshore for DE beaches. With breaking
waves of 2-3 feet, a medium period swell, and a new moon, the
risk for rip current development is MODERATE for New Jersey
beaches and LOW for Delaware beaches.

Rip currents occur often in the vicinities of jetties and
piers. Utilize any guarded beaches if venturing out into the
water. For specific beach forecasts, visit weather.gov/beach/phi

&&

.TIDES/COASTAL FLOODING...
Went ahead and issued a Coastal Flood Advisory for southern NJ,
southern DE, as well as the Delaware Bay counties and Delaware
River counties for this high tide cycle tonight. The threat
for widespread minor flooding increases as winds strengthen then
turn and become shore parallel on Thursday, potentially
trapping water along the coast. In addition, tide cycles will be
elevated due to the New Moon on Thursday. Will continue to
monitor upcoming high tides and make adjustments to the forecast
accordingly. Additional Coastal Flood Advisories may be needed
for the Thursday night high tide cycles.

Overall, the threat for tidal flooding appears to be lower
along the Chesapeake Bay than elsewhere in the region but by the
early morning high tide Thursday, water levels may also
approach spotty minor.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory from midnight tonight to 5 AM EDT
     Thursday for PAZ070-071-106.
NJ...Coastal Flood Advisory from 9 PM to 11 PM EDT this evening for
     NJZ016.
     Coastal Flood Advisory from 7 PM this evening to 1 AM EDT
     Thursday for NJZ021>025.
     Coastal Flood Advisory from midnight tonight to 5 AM EDT
     Thursday for NJZ015-017>019.
DE...Coastal Flood Advisory from 9 PM to 11 PM EDT this evening for
     DEZ001.
     Coastal Flood Advisory from 7 PM this evening to 1 AM EDT
     Thursday for DEZ002>004.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Deal
NEAR TERM...DeSilva/MPS
SHORT TERM...Deal/MPS
LONG TERM...Deal/MPS
AVIATION...Deal/DeSilva/MPS
MARINE...Deal/DeSilva
TIDES/COASTAL FLOODING...