Chester, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

261
FXUS61 KPHI 152329
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
729 PM EDT Sun Mar 15 2026

.WHAT HAS CHANGED...
Wind Advisory issued for southern and central New Jersey and
southern and central Delaware for Monday afternoon and Monday
night.

Gale Watch upgraded to Gale Warning for all waters Monday into
Monday night. Small Craft Advisory issued for tonight for ocean
waters.

Confidence in potential severe weather continues to increase
for Monday into Monday night.

&&

.KEY MESSAGES...
1. There is an increasing potential for strong to severe
thunderstorms Monday into Monday night along and ahead of a
strong cold front. Even outside of storms, strong winds are
likely especially closer to the coast. Localized flash flooding
will also be possible, especially inland.

2. Cold and dry through mid-week before temperatures moderate
through next weekend.

&&

.DISCUSSION...
KEY MESSAGE 1...There is an increasing potential for strong to
severe thunderstorms Monday into Monday night along and ahead of
a strong cold front. Even outside of storms, strong winds are
likely especially closer to the coast. Localized flash flooding
will also be possible, especially inland.

Mid level ridging today will give way as a deepening surface
low pressure system develops on the lee side of the Rockies this
afternoon. The upper level associated trough rapidly turns
negatively tilted and leads to a strong mid latitude cyclone
developing over the Great Lakes. This system will continue to
push north towards James Bay in Quebec and will usher in a
potent cold front over the region Monday evening.

A warm front will push north through the region Monday morning
bringing the warm sector of the cyclone over the Mid Atlantic.
This will usher in both warmer temperatures and higher dew
points. The southerly flow associated with this system will
transport a deep moisture plume into the region ahead of the
frontal system. Guidance is depicting significant height falls
along with a strong upper level jet with the right rear located
right over the Mid Atlantic. The combination of strong warm air
advection and upper level dynamics will promote lift across the
region on Monday.

Low level wind shear will be quite strong just ahead of the
frontal passage and the combination of dynamic lift, sufficient
moisture, and modest instability will support organized
convection Monday. Instability will be the limiting factor
however the dynamics should play a strong enough role in
overcoming that instability. High res guidance show sufficient
low level support to see STP values greater than 0.5-1 during a
brief window Monday late afternoon/evening. It is worth noting
that the outlook from the Storm Prediction Center continues the
ENHANCED risk of severe weather in our County Warning Area.

Something to note, is that if the dewpoints surge higher than
initially forecast, instability will increase quite a bit, and
this would lead to the potential for some isolated supercells to
develop. The primary threat remains wind, however the threat
for tornados is increasing. Shear vectors are generally
supportive of QLCS type tornadoes and these are often the
hardest type of tornado to issue warnings for as they can be
very are brief in nature.

Finally, it should be noted that even outside of any
thunderstorms the strong wind field will support southerly winds
gusting at least 35 to 45 mph Monday into Monday night, locally
up to 50 mph. This will help usher in an unseasonably warm and
humid airmass. A Wind Advisory has been issued for locations
mainly southeast of I-95 and US 13 just for the synoptic flow
winds late Monday and Monday evening.

In addition to the severe weather and strong wind threat, the
showers/storms will likely be producing heavy rainfall as PWATs
are progged to be 1.1-1.4" which is above the 90th percentile
for early March. MMEFS guidance is showing modest rises in
rivers so we`ll continue to watch for any potential hydro
concerns.


KEY MESSAGE 2...Cool and dry weather expected through Wednesday
before moderating through next weekend.

A much colder airmass filters in for Tuesday and Wednesday as a deep
upper trough will be situated over the eastern CONUS. At the
surface, broad high pressure near the Gulf Coast on Tuesday will
shift northeast over the Mid-Atlantic on Wednesday. This will yield
dry conditions under mostly sunny skies with highs mainly in the mid
30s to mid 40s. However, the pressure gradient will be tight over
the area, so post-frontal winds with gusts up to 30-35 mph are
possible on Tuesday. Also, with drier air filtering in, MinRH values
are expected to fall into the 25-35% range. Depending on how wet
fuel moistures are from antecedent rainfall, this may pose a threat
for potential fire spread. Winds will diminish Tuesday night into
Wednesday, limiting such threat.

By late week and into the weekend, temps begin to moderate back to
seasonable and eventually seasonably warm levels. At this point, the
next chance for precipitation is expected to be Friday night into
Saturday with the next disturbance tracking north of the area.
Shower chances range from 20-40%.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...VFR to start, with ceilings quickly dropping to MVFR
and then IFR by 03-05Z. Showers and a few embedded thunderstorms
are expected after 03Z. Have included VCTS to reflect increased
confidence in a few thunderstorms. East-southeast wind around
10 kt with a few gusts 15-20 kt becoming more south-southeast
approaching 12Z. LLWS at all terminals 40-50 kt out of the
south-southeast. Low confidence.

Monday...IFR to LIFR ceilings. Periods of showers and
thunderstorms expected at times, with visibility restrictions as
well. South-southeasterly wind 15-20 kt with gusts 35-40 kt.
The highest gusts are anticipated at MIV and ACY. A line of
strong to severe thunderstorms will likely begin impacting the
terminals from west to east after 21-22Z. LLWS at all terminals
45-55 kt out of the south. Low confidence.

Monday night...IFR to LIFR ceilings in the evening, gradually
lifting to MVFR after 03Z and VFR approaching 12Z Tuesday. Line
of strong to locally severe thunderstorms will likely clear all
terminals by 04-06Z. LLWS at all terminals in the evening 45-55
kt out of the south. Moderate confidence.

Outlook...

Tuesday through Tuesday night...VFR. Gusty west winds up to 30 kt
possible during the afternoon, diminishing into the evening.

Wednesday through Friday...VFR. No significant weather expected.

&&

.MARINE...
Sub-SCA rest of the day. Building southerly flow will bring seas
of 5-7 feet tonight, with SCA in effect for ocean waters.
Continued increase in southerly flow on Monday will bring gale
gusts, especially late in the day and during the evening, with
Gale Warning now in effect. Gusty thunderstorms also possible,
mainly later in the day and during the evening. Winds start to
diminish late in the night.

Outlook...

Tuesday through Tuesday night...SCA conditions likely. West winds
around 20-30 kt with seas around 5-8 feet.

Wednesday...Lingering SCA conditions possible. Winds generally below
20 kt with seas around 3-5 feet.

Wednesday night through Friday...No marine headlines expected. Winds
mostly below 15 kt with seas around 2-4 feet.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Wind Advisory from 2 PM Monday to 2 AM EDT Tuesday for
     NJZ012>014-016>027.
DE...Wind Advisory from 2 PM Monday to 2 AM EDT Tuesday for
     DEZ002>004.
MD...None.
MARINE...Gale Warning from 6 AM Monday to 2 AM EDT Tuesday for ANZ430-
     431-450>455.
     Small Craft Advisory until 6 AM EDT Monday for ANZ450>455.

&&

$$

DISCUSSION...Deal/DeSilva/RCM
AVIATION...Cooper/Deal/DeSilva/RCM
MARINE...Deal/DeSilva/RCM