FXUS61 KPHI 261839

AFDPHI



Area Forecast Discussion

National Weather Service Mount Holly NJ

239 PM EDT Thu Jun 26 2025



.SYNOPSIS...

A cold front will continue to settle southward across our area 

through tonight and then remain just to our south through 

Friday. The front gradually lifts northward as a warm front 

Saturday, followed by a weak cold front stalling nearby on 

Sunday. The front then shifts northward as a warm front Monday 

followed by a cold front later Tuesday. High pressure builds 

closer later Wednesday into Thursday.



&&



.NEAR TERM /THROUGH FRIDAY/...

As of early this afternoon, the back door cold front stretches

from near Allentown south to near Philly and southeast towards

Atlantic City. Locations north and east have cooled and clouded

up considerably. Further south and west, warmth and humidity

remain, and in fact it turned out the need was present to expand

the heat advisories up into Philly metro once again as heat

indices are meeting the early-season criteria once again. 



Where the front has yet to reach, heat and instability have

increased, and storms are starting to develop. As these storms

start to intersect the southwestward moving front, they may

stall on the boundary, which could result in a locally heavy

rain and flood threat. HREF was most bullish across areas just

northwest and southwest of our forecast area, but enough of a

signal is present to give us confidence in posting a flood watch

for our westernmost zones in PA thru this evening. Storms may

make their way further east, with a lesser but still present

heavy rain threat, but the highest risk definitely appears to 

be in the far west. There is also an increasing severe risk as

the front backs slowly south and west, with greater than

expected CAPE available, SPC has coordinated a severe

thunderstorm watch mainly for locations west and south of Philly

thru 10 PM.



Later tonight as convection winds down, the front will sweep

southwest and blanket most of the region with low clouds and a

much cooler east to northeast wind. Lows will be in the 50s

Poconos, 60s most elsewhere, but near 70 southern Delmarva

zones. 



A low cloud deck will dominate Friday on the easterly flow north

of the front, which will stall just to our south. Some showers

and spotty thunderstorms may develop via disturbances passing

aloft and elevated instability, but severe and flood risk look 

lower. Temperatures will struggle to reach 70 across 

north/central NJ, likely failing to do so in the Poconos, but 

may touch 80 across the eastern shore of MD and far southern DE.



&&



.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...

The much cooler conditions will ease as the onshore flow 

weakens and is replaced by a southerly return flow.



An easterly flow regime is forecast to remain in place Friday 

night and to start Saturday. This will then ease as surface high

pressure shifts east toward the northern Atlantic. This along 

with low pressure tracking north of the Great Lakes and toward 

northern Maine Saturday will result in a more return flow 

setting up across our area during Saturday. This will send a 

warm front northward during Saturday, bringing a much warmer and

increasingly more humid air mass back into our region for 

weekend. A weak cold front then looks to settle into our area 

Saturday night before stalling on Sunday. 



As this occurs, some showers and thunderstorms will be possible

given the initial warm air advection and moisture advection. 

This will increase the instability each day, with the 

probability of precipitation the greatest Saturday afternoon 

across mainly our northern and western zones. As the main system

slides by well to our north later Saturday, any severe 

thunderstorm risk looks rather low. The pattern may repeat on 

Sunday where some showers and thunderstorms will again be 

possible, especially during the peak heating hours of the 

afternoon and early evening. Temperatures are forecast to top 

out at 90 degrees for some places each afternoon, especially 

across the southern half of the area away from the immediate 

coast. The heat indices for the majority of the area should stay

below 100 degrees each afternoon (a bit lower Sunday given some

lowering of the surface dew points).



&&



.LONG TERM /MONDAY THROUGH THURSDAY/...

Summary...Potentially unsettled at times with no extreme heat 

forecast.



Synoptic Overview...An upper-level trough is forecast to move 

into much of the East by later Tuesday, then remain in place 

through Thursday with it potentially amplifying some. At the 

surface, a boundary across our area will start to lift north as 

a warm front Monday, then a cold front moves through later 

Tuesday. High pressure then builds closer later Wednesday into 

Thursday.



For Monday and Tuesday...An upper-level trough across the 

Midwest and adjacent Canada Monday is forecast to shift eastward

and amplify some. This overspreads the Northeast with it 

possibly amplifying a bit more as stronger shortwave energy 

rounds the base of the trough. This will drive a cold front 

toward our area later Monday, then cross our region by later 

Tuesday. Increasing mid level flow will result in an uptick in 

shear and instability should be sufficient enough for some 

thunderstorm development. There could be some severe 

thunderstorm risk Tuesday afternoon as the cold front arrives in

tandem with the incoming upper-level trough. Some showers or 

thunderstorms cannot be ruled out on Monday especially in the 

afternoon and evening, primarily tied to a surface trough. 

Temperatures will make a run at 90 degrees for many areas with 

Tuesday potentially the hotter day as dew points surge ahead of 

the cold front. While it will be rather warm and humid, extreme 

heat is currently not forecast.



For Wednesday and Thursday...The upper-level trough across the 

Northeast and Mid-Atlantic may tend to sharpen again as 

additional energy rounds its base. The cold front should be 

south and east of our area to start Wednesday, and while 

temperatures do not look to drop much, the dew points are 

forecast to lower some in the wake of the cold front. Despite 

the presence of the upper-level trough, less in the way of 

deeper moisture should keep the instability lower as well. Given

surface high pressure building closer to our area later 

Wednesday and especially Thursday, the chance for any showers 

and thunderstorms at this time looks to be rather low.



&&



.AVIATION /19Z THURSDAY THROUGH TUESDAY/...

Rest of today...Mainly VFR, but sub-VFR possible mainly from 

PHL north and east as backdoor front brings stratus deck. Spotty

showers/t-storms possible during the afternoon especially 

western terminals. Winds turning northeasterly 5-10 kts. Low 

confidence.



Tonight...Sub-VFR conditions likely with IFR possible. Scattered

storms this evening give way to widespread low stratus later at

night. Winds northeast to east 5-10 kts. Low confidence.



Friday...Sub-VFR conditions likely with IFR possible. Scattered

showers possible, but main concern will be continued low stratus

deck which likely lingers most if not all day. Winds still east

to northeast 5-10 kts. Low confidence.



Outlook...



Friday night...MVFR/IFR ceilings due to low clouds. Some 

showers are possible which could result in visibility 

restrictions at times.



Saturday...IFR or MVFR ceilings improve to VFR. Some showers or

thunderstorms possible.



Sunday and Monday...A few showers and thunderstorms, resulting 

in lower ceilings/visibilities at times, are possible.



Tuesday...Some showers and thunderstorms probable with local 

restrictions.



&&



.MARINE...

Small Craft Advisory thru Friday afternoon fornorthern two NJ 

marine zone given northeast flow gusting 25-30 kts which likely 

continues into Friday, with seas building to 3-5 feet. Rest of 

zones should see NE winds 10-15 kts with some gusts up to 20 

kts thru Friday and seas of 2-4 feet. A spotty gusty 

thunderstorm possible this afternoon/evening. 



Outlook... 



Friday night through Tuesday...The conditions are anticipated 

to be below Small Craft Advisory criteria.



&&



.TIDES/COASTAL FLOODING...

The recent New Moon and increasing onshore flow will lead to higher

confidence in advisory level tidal flooding occurring this evening.

While we get away from the New Moon, onshore flow will result in

water piling up and more widespread minor tidal flooding for the

coastal and Delaware Bay communities. It appears that the higher

water levels will only be for one tide cycle, but we'll monitor

later today to assure that this trend continues. 



No tidal flooding is expected within the tidal Delaware River or 

Chesapeake Bay.



&&



.PHI WATCHES/WARNINGS/ADVISORIES...

PA...Heat Advisory until 8 PM EDT this evening for PAZ070-071-102-

     104.

     Flood Watch until midnight EDT tonight for PAZ054-060-061-101-

     102.

NJ...Heat Advisory until 8 PM EDT this evening for NJZ017-018.

     Coastal Flood Advisory from 10 PM this evening to 2 AM EDT 

     Friday for NJZ016.

     Coastal Flood Advisory from 7 PM this evening to 1 AM EDT 

     Friday for NJZ012>014-020>027.

DE...Heat Advisory until 8 PM EDT this evening for DEZ001>003.

     Coastal Flood Advisory from 10 PM this evening to 2 AM EDT 

     Friday for DEZ001.

     Coastal Flood Advisory from 7 PM this evening to 1 AM EDT 

     Friday for DEZ002>004.

MD...Heat Advisory until 8 PM EDT this evening for MDZ012-015-019-

     020.

MARINE...Small Craft Advisory until 6 PM EDT Friday for ANZ450-451.



&&



$$



SYNOPSIS...Gorse/RCM

NEAR TERM...RCM

SHORT TERM...Gorse

LONG TERM...Gorse

AVIATION...Gorse/RCM

MARINE...Gorse/RCM

TIDES/COASTAL FLOODING...PHI

