Damaging Wind in New Jersey, May 6, 2025

Area Forecast Discussion
National Weather Service Mount Holly NJ
308 PM EDT Tue May 6 2025

.SYNOPSIS...
An upper level low will slowly move across the Northeast and Mid-
Atlantic regions tonight, then it will lift out of the region on
Wednesday. A cold front will cross our area Wednesday night and
Thursday morning. Another upper level low develops across the
Northeast and Mid-Atlantic regions Thursday night and Friday with
weak low pressure nearby, before shifting northeast on Saturday. A
cold front may then move through during Sunday with high pressure
returning by early next week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
A Severe Thunderstorm Watch is in effect for eastern Pennsylvania
and parts of central to northern New Jersey until 8 PM.

A closed low will cross our area tonight and then shift across New
England during Wednesday as it gradually weakens. Ahead of the
center of this feature, a lobe of strong shortwave energy will lift
across much of our area this afternoon into early this evening.
There will be an area of stronger forcing for ascent accompanying
this, with this mostly focused across eastern Pennsylvania to
northern New Jersey. A belt of stronger south to southwesterly flow
with it has resulted in an uptick in the shear (around 40 knots)
across these areas especially and when combined with up to 1000 J/kg
of MLCAPE will continue to support convection.

The strongest storms so far have organized into a cluster or band
across parts of eastern Pennsylvania as they continue to lift
northward. Given steeper lapse rates and colder air aloft, some of
the stronger convective cores may produce locally damaging winds and
large hail. To cover this threat, a Severe Thunderstorm Watch was
issued for eastern Pennsylvania and portions of central to northern
New Jersey until 8 PM. There continues to be lower confidence with
the far eastern extent of this watch (across parts of central and
northern New Jersey to Philadelphia) as stronger forcing main remain
a bit more to the north/west. To the south and east of Philadelphia,
convective coverage looks to be rather limited and therefore PoPs
continue to be the lowest here. The convection is expected to weaken
or lift to our north this evening, then much of the guidance does
not have much shower activity through the overnight hours. There
looks to be a stronger shortwave though on the south side of the
closed low overnight that approaches our area, and some guidance
shows some light showers with that especially in parts of our
western zones. Cloud cover may tend to fill back in again through
the night as the mixing wanes and the main core of the closed low
arrives. Drier air has mixed down to the surface across Delmarva
especially where dew points have dropped through the 50s with even
some upper 40s reported. These should recover some early this
evening. Overall though, dew points will come down some across the
entire region through the overnight as some drier arrives on the
south side of the closed low.

As we go through Wednesday, the closed low continues to depart our
area and the cyclonic flow weakens. While a few showers cannot be
ruled out especially through midday, they look to be spotty given
enough drying arriving in the wake of the closed low. This should
also result in more sunshine through the day along with a west or
west-southwest breeze. High temperatures are forecast to be in the
70s across much of the area, although cooler along the coast as the
winds should be light enough to result in a more southerly wind
component.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
By Wednesday night, the upper low will have departed the region
where a brief period of zonal flow orients itself over the area.
However, this will be short-lived as another upper level trough
begins to pivot into the region on Thursday. This feature is also
expected to close off in nature, just like its predecessor as it
pivots over the Northeast through Friday, before lifting out of the
region by Friday night.

As a result, we'll have partly to mostly cloudy skies in place for
Wednesday night with lows in mostly in the 50s and light winds.
Clouds will continue to increase on Thursday, especially during the
afternoon as a round of showers and thunderstorms are expected to
develop across the region and linger into the early evening hours.
Considering the placement of the upper low and the abundance of
cloud cover expected, it is not too certain on how much we may
destabilize during the afternoon. High temperatures will be in the
upper 60s to upper 70 across much of the area regardless. For now,
the severe potential appears to be low, but a few thunderstorms are
certainly plausible at times time. Showers will likely continue into
Thursday night, but with the loss of diurnal heating, any activity
should generally be showery in nature. Lows on Thursday night will
remain quite seasonable in the 40s and 50s.

By Friday, the closed low will settle near/over New York State, with
surface low pressure developing either over or just off the coast of
New Jersey. Showers will continue to develop throughout the course
of the day with a few embedded rumbles of thunder possible as well.
High temperatures will be noticeably cooler than those on Thursday,
as highs on Friday will only be in the upper 50s to upper 60s.
Overall, a damp day is expected to close out the week. The surface
low will depart by Friday night as the upper level low exits the
region. The shower activity will then cease from southwest to
northeast as the low departs. Lows on Friday night will generally be
in the 40s to around 50 degrees with skies improving from mostly to
partly cloudy.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
For Saturday through Monday...A rather benign weather period is
expected to occur for the weekend into early next week with dry
conditions (PoPs less than 10%) and gradually warming temperatures.
Mostly sunny skies during the day and mostly clear skies at night
are expected through the period. Highs in the upper 60s to low 70s
on Saturday will gradually warm low to mid 70s on Sunday and into
the mid to upper 70s by Monday.

For Monday night into Tuesday...A deep closed low over the Gulf
Coast will begin to migrate northeastward into the Tennessee Valley
by mid week. At the surface, an area of low pressure will be making
its way northward over the Carolinas into the Mid-Atlantic states on
Tuesday. This will allow a chance of showers to be introduced into
the southern portions of the forecast area beginning Monday night
and a slight chance of showers into the remainder of the forecast
area on Tuesday. Temperatures are expected to be around 5 degrees
above normal for mid-May.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of this afternoon...Mainly VFR cloud bases. Some showers and
thunderstorms around, with the most coverage north and west of KPHL.
Included a TEMPO for thunderstorms at KRDG and KABE and then VCTS
for the I-95 terminals. Opted to not include a thunder mention at
KMIV and KACY given much lower chances/coverage. Some locally strong
wind gusts possible with a few of the thunderstorms mainly
north/west of KPHL. Southeast winds 8-12 knots with some local gusts
up to 20 knots, becoming south to southwest. Moderate confidence
overall.

Tonight...Some showers and thunderstorms end during the evening,
then mainly dry with VFR ceilings. Southwest to west winds near 5
knots, becoming locally light and variable. Moderate confidence.

Wednesday...VFR ceilings should scatter out. A few showers possible
through about midday. Westerly winds mostly 10 knots or less,
however a sea breeze may be close to KACY later in the afternoon.
Moderate confidence.

Outlook...

Wednesday night...VFR. No significant weather expected.

Thursday through Friday...Sub-VFR conditions expected, especially
for Thursday night and Friday. Periods of rain showers likely with
isolated thunderstorms possible.

Friday night through Sunday...VFR expected. Other than a slight
chance of a shower on Friday night, no significant weather
anticipated.

&&

.MARINE...
Some stratus and fog eroding northward across the New Jersey waters
this afternoon, however the fog does not appear to be dense.
Otherwise, the conditions are anticipated to be below Small Craft
Advisory criteria through Wednesday. A few showers or a thunderstorm
will be possible into this evening.

Outlook...

Wednesday night through Thursday night...No marine headlines
expected. Winds of 15 kt or less with seas around 2-4 feet. Fair
weather on Wednesday night with a chance for showers and isolated
thunderstorms on Thursday into Thursday night.

Friday through Friday night...SCA conditions possible mainly due to
seas. Winds of 10-20 kt with seas around 3-5 feet. Periods of rain
showers and isolated thunderstorms possible.

Saturday through Sunday...No marine headlines expected. Winds of 15
kt or less with seas around 2-4 feet. Fair weather.

&&

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

&&

SYNOPSIS...DeSilva/MJL
NEAR TERM...Gorse
SHORT TERM...DeSilva/MJL
LONG TERM...DeSilva/MJL
AVIATION...DeSilva/Gorse
MARINE...DeSilva/Gorse

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
212 PM EDT Tue May 6 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0205 PM     Hail             Exton                   40.03N 75.63W
05/06/2025  M0.25 Inch       Chester            PA   Trained Spotter

            Pea sized hail.

&&

NG

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
255 PM EDT Tue May 6 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0225 PM     Tstm Wnd Dmg     1 SE Fleetwood          40.44N 75.80W
05/06/2025                   Berks              PA   Fire Dept/Rescue

            Multiple trees and wires down along Orchard
            Rd. Time estimated from radar.

&&

DeSilva

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
320 PM EDT Tue May 6 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0218 PM     Tstm Wnd Dmg     3 NNE Mount Penn        40.37N 75.86W
05/06/2025                   Berks              PA   Broadcast Media

            Alsace Township: Snyder Rd and Antietam Rd.
            Tree Down. Time estimated from radar.

&&

DeSilva

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
430 PM EDT Tue May 6 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0251 PM     Hail             Royersford              40.19N 75.54W
05/06/2025  E0.50 Inch       Montgomery         PA   Public

            Report from mPING: Half-inch (0.50 in.).

&&

DeSilva

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
434 PM EDT Tue May 6 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0349 PM     Hail             2 S Bushkill Twp        40.78N 75.34W
05/06/2025  E0.50 Inch       Northampton        PA   Public

            Report from mPING: Half-inch (0.50 in.).

&&

DeSilva

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
435 PM EDT Tue May 6 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 PM     Hail             2 N Arlington Heights   41.02N 75.20W
05/06/2025  E0.50 Inch       Monroe             PA   Public

            Report from mPING: Half-inch (0.50 in.).

&&

DeSilva