034 
FXUS61 KPHI 191037
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
637 AM EDT Sun Oct 19 2025

.SYNOPSIS...
High pressure gradually moves away from our region through the 
day today. A strong cold front moves through the region late 
tonight into Monday, followed by weak high pressure returning 
Monday night into Tuesday. Another cold front moves through 
Tuesday night into Wednesday, then high pressure builds in from
the south beginning Thursday to end the week.

&&

.NEAR TERM /THROUGH MONDAY/...
A strong cold front crosses our area late tonight and early Monday
morning.

A strengthening upper-level trough slides across our region tonight 
and Monday. Much of the guidance continues to indicate that this 
trough takes on some negative tilt as it crosses our area early 
Monday morning. The trough may even close off in our area as a 
strong low to mid level jet maximum rotates up across the eastern 
side of the trough. Surface low pressure tracks across the eastern 
Great Lakes into Monday, however a secondary low looks to develop at 
the triple point near our area as the core of the trough arrives.

Given the strength of this trough, southerly flow will increase 
today and tonight ahead of it and that will ramp up the warm air 
advection. It will be dry today with some increase in mainly high 
level clouds, with high temperatures soaring into the mid to upper 
70s for many areas. Some spots could reach 80F especially along the 
urban I-95 corridor. The low-level flow will be more south-southeast 
for a time today and that will keep it a little cooler for coastal 
areas. The flow will increase during the day as the pressure 
gradient tightens, and with better mixing occurring through the 
afternoon, a gusty southerly breeze is expected. The moisture return 
is forecast to be on the increase as well today with dew points 
increasing through the 50s, then even into the low 60s tonight.

As a robust low-level jet (925-850 mb flow increases to 40-50 knots) 
arrives tonight, forcing for ascent will start to overspread our 
area especially as the leading edge of the incoming trough arrives. 
A band of showers looks to arrive from west to east starting late 
this evening and lasting into the early morning hours of Monday. It 
is possible that an initial band of showers quickly moves through, 
then a narrow low-topped convective band sweeps through just ahead 
of or with the cold front in the early morning hours. It is 
especially with the narrow convective band where some stronger wind 
gusts could be mixed down to the surface. The instability is still 
forecast to be rather weak given the timing of the system and also 
poor low to mid level lapse rates. The setup continues to point 
toward a low CAPE/high shear environment as the strong low to mid 
level wind fields will result in very strong shear. The rather weak 
instability and low topped nature of convection would limit any 
lightning, and should limit any severe weather threat to locally 
strong/damaging wind gusts. Something to watch though given the 
magnitude of the shear and forcing is any low-level rotation 
especially if a stronger QLCS (or narrow line segments) ends up
developing. The SPC has added a 2 percent tornado potential for
much of our area given the magnitude of the shear combined with
an area of better moisture overnight and early Monday morning.

The cold front shifts to our east to start Monday with the main 
forcing for ascent already to our east and northeast. Some 
wraparound showers may linger for a time mainly in the morning 
across our northern to western areas before drier air takes hold. 
Given an increase in cold air advection and deeper mixing during the 
day Monday, a gusty (25-35 mph) west to west-northwest breeze 
occurs. High temperatures on Monday will be 10-15 degrees lower than 
today.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
In the wake of the cold front Monday night, a brief period of
dry conditions is expected before the next wave arrives Tuesday
night into Wednesday.

Temperatures Monday night will return to the upper 30s to mid
40s with cold air being advected in behind the front but a
lingering breeze around 5-10 mph should keep the area from
completely bottoming out. Heading into Tuesday, a modest 
warming trend is expected thanks to weak short wave ridging in 
the mid and upper levels. Temperatures in the mid-upper 60s are
forecast.

The next cold front is then expected to arrive Tuesday night 
and Wednesday. The closed mid and upper level low associated 
with this front is further north and west (further away from our
region). As such, don't expect as much synoptic scale lift in 
our region. Nonetheless, scattered to numerous showers will be 
possible with the mesoscale lift near and just behind the cold 
front, with the greatest coverage expected in the northern half 
of the region closer to the low. PoPs generally range from 
40-60% with lower chances in southern Delmarva. Given the 
displacement from the greatest forcing, risk for hazardous 
weather is very low with this front (less than 5%).

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
In the wake of the Tuesday night-Wednesday cold front, attention
turns to the potential for more frost and freeze in areas where
the growing season continues as sub 40 degree temperatures are
expected across much of the region. The coldest night in the
forecast currently is Thursday night with light winds and clear
skies expected with high pressure building in. For now have 
stayed with a standard blend of guidance, but will be watching 
the guidance trends in this period closely.

High pressure looks to remain in control through the end of the
week, resulting in mostly dry conditions and high temperatures
mainly in the mid 50s to low 60s.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY and surrounding areas.

Today...VFR. Calm to light and variable winds early becoming 
southeast to south 5-10 knots during the morning, then increasing
to 10-15 knots with gusts to 25 knots in the afternoon. Moderate
confidence.

Tonight...VFR ceilings may lower to a period of mainly MVFR ceilings 
after 03z from west to east as a round of showers moves through. 
Times of MVFR or IFR visibilities with showers. A brief thunderstorm 
cannot be ruled out after 04z (not included in the TAFs due to 
low probabilities of occurrence). Southerly winds 8-12 knots 
with some gusts to around 20 knots, becoming southwest to west-
southwest late. Some higher gusts possible with a narrow line of
heavier showers overnight. Low confidence regarding the timing 
details.

Monday...Areas of sub-VFR conditions with some showers possible 
early, otherwise VFR ceilings gradually decreasing. West to west-
northwest winds around 15 knots with gusts up to 30 knots. Moderate 
confidence. 

Outlook...

Monday night...VFR with a diminishing wind.

Tuesday...VFR.

Tuesday night...Periods of MVFR or lower possible in showers.

Wednesday and Thursday...VFR.

&&

.MARINE...
A Small Craft Advisory begins at 10 AM today for the New Jersey and 
Delaware Atlantic coastal waters and at 1 PM today for Delaware Bay.

Southerly winds today increase to 15-25 knots with gusts up to 30 
knots. Seas build to 4-6 feet. The strong winds and elevated seas 
continue tonight, and there is some potential for a brief period of 
gale force wind gusts as the strongest part of the low-level jet 
crosses our area. This however will be contingent on if showers and 
isolated thunderstorms are strong enough to mix down the stronger 
winds. Maintained a Small Craft Advisory, but may need some Special 
Marine Warnings if the heavier showers are coincident with the low-
level jet being overhead. A wind shift from southerly to westerly 
occurs with the passage of a cold front late tonight.

For Monday, Small Craft Advisory conditions with gusty westerly 
winds. An offshore wind will result in the seas gradually lowering 
through the day.

Outlook... 

Monday night...SCA conditions may linger at least in the evening.

Tuesday through Thursday...Winds and seas should generally stay 
below SCA criteria. However, some guidance has waves on the coastal 
waters briefly increasing above 5 ft late Tuesday as the winds 
become more southwesterly.

&&

.TIDES/COASTAL FLOODING...
With the southerly flow developing, we have now had three 
consecutive high tide cycles with flooding in back bays, 
particularly in Ocean County NJ and Sussex County DE. Given that
the southerly flow will persist today, would expect back bay 
flooding will continue through at least the next couple high 
tide cycles. A Coastal Flood Advisory for those two counties is
in effect until Noon today to include the morning high tide cycle.

We are also closely watching tidal departures on the northeastern
portions of the Chesapeake Bay, as this flow regime can result 
in tidal flooding there as well. The latest high tide showed 
water levels just below advisory criteria with spotty minor 
tidal flooding occurring in some spots. Therefore, confidence 
has increased that with southerly flow continuing through the 
day, that widespread minor tidal flooding will occur with the 
late afternoon/evening high tide cycle. A Coastal Flood Advisory
has been issued for the Eastern Shore of Maryland as a result.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Advisory until noon EDT today for NJZ020-026.
DE...Coastal Flood Advisory until noon EDT today for DEZ003-004.
MD...Coastal Flood Advisory from 6 PM to 10 PM EDT this evening for 
     MDZ012.
     Coastal Flood Advisory from 3 PM this afternoon to 8 PM EDT 
     this evening for MDZ015-019-020.
MARINE...Small Craft Advisory from 1 PM this afternoon to 6 PM EDT 
     Monday for ANZ430-431.
     Small Craft Advisory from 10 AM this morning to 6 PM EDT 
     Monday for ANZ450>455.

&&

$$

SYNOPSIS...AKL/Johnson
NEAR TERM...Gorse
SHORT TERM...AKL
LONG TERM...AKL
AVIATION...AKL/Gorse
MARINE...AKL/Gorse
TIDES/COASTAL FLOODING...AKL