Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 288, NWS Philadelphia/Mount Holly

August 8, 2026New Castle County, Delaware; Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 8, 2026, 1:26 PM EDT for New Castle County, Delaware; Chester County, Delaware County, Pennsylvania. It was in force for 49 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 8, 2026, 1:26 PM EDT (17:26 UTC)
Expired
Aug 8, 2026, 2:15 PM EDT
In force
49 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties New Castle County, DE, Chester County, PA, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 116 km from the middle of the area, began a volume at 17:29 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 8, 1:12 PM EDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.4 hours before the alert went out and 173 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2026-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 63 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2026-08-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -28 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
63 J/kg
Mixed-layer CIN
-124 J/kg
Mixed-layer LCL
1367 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
-28 m²/s²
0-3 km storm-relative helicity
28 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

078 
WUUS51 KPHI 081726
SVRPHI
DEC003-PAC029-045-081815-
/O.NEW.KPHI.SV.W.0288.260808T1726Z-260808T1815Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
126 PM EDT Sat Aug 8 2026

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northern New Castle County in northern Delaware...
  Southern Chester County in southeastern Pennsylvania...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 215 PM EDT.

* At 126 PM EDT, a severe thunderstorm was located near West Grove,
  or 13 miles northwest of Newark, moving east at 35 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  Wilmington, West Chester, Coatesville, Westtown, Downingtown,
  Elsmere, Kennett Square, Oxford, Parkesburg, West Grove, Arden,
  Cheyney, Talleyville, Elam, Marshallton, Chelsea, Gradyville,
  Greenville, Landenberg, and Hockessin.

This includes the following highways...
 Interstate 95 in Pennsylvania between mile markers 0 and 1.
 Interstate 95 in Delaware between mile markers 14 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather, contact your nearest law enforcement
agency. They will send your report to the National Weather Service
office in Mount Holly NJ.

&&

LAT...LON 3997 7598 4006 7542 3979 7542 3977 7546
      3974 7547 3971 7579 3972 7579 3972 7595
      3993 7599 3994 7598 3995 7600
TIME...MOT...LOC 1726Z 263DEG 30KT 3986 7587 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MPS
3 follow-up statements
351 
WWUS51 KPHI 081747
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
147 PM EDT Sat Aug 8 2026

DEC003-PAC029-045-081815-
/O.CON.KPHI.SV.W.0288.000000T0000Z-260808T1815Z/
New Castle DE-Chester PA-Delaware PA-
147 PM EDT Sat Aug 8 2026

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 215 PM EDT
FOR NORTHERN NEW CASTLE...SOUTHEASTERN CHESTER AND SOUTHWESTERN
DELAWARE COUNTIES...

At 147 PM EDT, a severe thunderstorm was located over Kennett Square,
or 7 miles southwest of West Chester, moving east at 40 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Wilmington, West Chester, Coatesville, Westtown, Kennett Square, West
Grove, Arden, Cheyney, North Star, Talleyville, Elam, Marshallton,
Lima, Chelsea, Ashland, Gradyville, Greenville, Landenberg,
Concordville, and Hockessin.

This includes the following highways...
 Interstate 95 in Pennsylvania between mile markers 0 and 1.
 Interstate 95 in Delaware between mile markers 15 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Mount Holly NJ.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3974 7582 3999 7584 4001 7542 3979 7542
      3977 7546 3975 7547
TIME...MOT...LOC 1747Z 268DEG 35KT 3988 7571 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MPS
762 
WWUS51 KPHI 081803
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
203 PM EDT Sat Aug 8 2026

DEC003-PAC029-045-081815-
/O.CON.KPHI.SV.W.0288.000000T0000Z-260808T1815Z/
New Castle DE-Chester PA-Delaware PA-
203 PM EDT Sat Aug 8 2026

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 215 PM EDT
FOR NORTHEASTERN NEW CASTLE...SOUTHEASTERN CHESTER AND SOUTHWESTERN
DELAWARE COUNTIES...

At 202 PM EDT, a severe thunderstorm was located over Arden, or near
Wilmington, moving east at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Wilmington, Westtown, Elsmere, Arden, Greenville, Cheyney,
Talleyville, Elam, Lima, Concordville, Chelsea, Hockessin, Chester
Heights, Marcus Hook, Bellefonte, Ardentown, Ardencroft, Edgemoor,
Boothwyn, and Village Green-Green Ridge.

This includes the following highways...
 Interstate 95 in Pennsylvania between mile markers 0 and 1.
 Interstate 95 in Delaware between mile markers 15 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Mount Holly NJ.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3974 7566 3994 7560 3994 7542 3979 7542
      3977 7546 3975 7547
TIME...MOT...LOC 1802Z 274DEG 27KT 3982 7552 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MPS
830 
WWUS51 KPHI 081807 RRA
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
207 PM EDT Sat Aug 8 2026

DEC003-PAC029-045-081817-
/O.EXP.KPHI.SV.W.0288.000000T0000Z-260808T1815Z/
New Castle DE-Chester PA-Delaware PA-
207 PM EDT Sat Aug 8 2026

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN NEW CASTLE...
SOUTHEASTERN CHESTER AND SOUTHWESTERN DELAWARE COUNTIES WILL EXPIRE
AT 215 PM EDT...

The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However gusty
winds and heavy rain are still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 600 PM EDT for
northern Delaware...southern New Jersey...and southeastern
Pennsylvania.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Mount Holly NJ.

LAT...LON 3974 7566 3994 7560 3994 7542 3979 7542
      3977 7546 3975 7547
TIME...MOT...LOC 1807Z 263DEG 30KT 3982 7548 

$$

MPS

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Philadelphia/Mount Holly wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 8, 7:20 AM EDT, 6 hours 6 minutes earlier. Its key messages:

  • 1. Hot and humid conditions are expected to persist through Tuesday of next week, though an improvement in humidity is expected Sunday into Monday. A Heat Advisory is in effect for portions of the area through today. 2. Isolated to scattered showers and thunderstorms are forecast to develop this afternoon and evening. Sunday still looks to be largely dry, then daily chances for showers and thunderstorms will return Monday and into the middle of next week. There is at least a marginal risk for localized heavy rainfall leading to flash flooding and locally damaging wind gusts with any stronger thunderstorms that develop.
Area forecast discussion, Aug 8, 7:20 AM EDT, 6 hours 6 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
720 AM EDT Sat Aug 8 2026

.WHAT HAS CHANGED...
No significant changes to the forecast.

&&

.KEY MESSAGES...
1. Hot and humid conditions are expected to persist through
Tuesday of next week, though an improvement in humidity is
expected Sunday into Monday. A Heat Advisory is in effect for
portions of the area through today.

2. Isolated to scattered showers and thunderstorms are forecast
to develop this afternoon and evening. Sunday still looks to be
largely dry, then daily chances for showers and thunderstorms
will return Monday and into the middle of next week. There is
at least a marginal risk for localized heavy rainfall leading
to flash flooding and locally damaging wind gusts with any
stronger thunderstorms that develop.

&&

.DISCUSSION...
KEY MESSAGE 1...Hot and humid conditions are expected to
persist through Tuesday of next week, though an improvement in
humidity is expected Sunday into Monday. A Heat Advisory is in
effect for portions of the area through today.

A relatively stagnant synoptic pattern will remain in place
across our region. Quasi zonal mid and upper level flow will be
in place through the middle of next week as Bermuda high
pressure persists offshore. This will keep a steady stream of
very warm and moist air in place across the region through the
period.

A prolonged period of hot and humid conditions will continue
for the next several days. With dewpoints remaining in the low
to mid 70s and highs in the upper 80s to low 90s today, heat
indices will again be near 100 degrees this afternoon, mainly
along and southeast of the I-95 corridor. A weak cold frontal
passage Sunday will help usher in slightly drier air and allow
dewpoints to mix out during the afternoon hours both Sunday and
Monday. This will give some slight reprieve from the excessive
humidity, though highs will still be in the upper 80s to low or
even mid 90s. The lower dewpoints Sunday and Monday will result
in maximum heat indices mainly in the mid to upper 90s, though
could get near 100 degrees in Delmarva and far southern New
Jersey. Since the forecast is decidedly below Heat Advisory
criteria, we've opted not to extend it to cover additional days
at this time, though it will still be hot and humid.

A Heat Advisory remains in effect through 8 PM this evening for
portions of southeastern Pennsylvania, portions of New Jersey,
and northern Delware.

Moisture advection will return again by Tuesday ahead of
another cold front, and slightly more humid conditions should
return for Tuesday. A somewhat stronger cold front looks to come
through late Tuesday or Wednesday, which will help bring a
slight reduction in temperatures. Highs by Wednesday and
Thursday are mostly in the mid to upper 80s, which will be
closer to average for early to mid August.

KEY MESSAGE 2...Isolated to scattered showers and thunderstorms
are forecast to develop this afternoon and evening. Sunday
still looks to be largely dry, then daily chances for showers
and thunderstorms will return Monday and into the middle of next
week. There is at least a marginal risk for localized heavy
rainfall leading to flash flooding and locally damaging wind
gusts with any stronger thunderstorms that develop.

The evolution of today's convection remains a little unclear
still. A feature of interest will be the convective complex
currently across the upper Ohio Valley early this morning. While
that activity should weaken later this morning, it's remnants
will likely become a focus for forcing diurnally driven
convection in our region later today as it drifts eastward.
CAMs still suggesting isolated to scattered thunderstorms
developing across the area this afternoon and evening. Synoptic
forcing isn't as strong as what we had Friday, though the
remnant dynamics from the convection upstream could give us
better forcing at the mesoscale level. So we could see more
widespread thunderstorms than CAMs suggest, but not super
confident on that at the moment. PWATs look slightly lower than
today, but overall the thermodynamics appear similar to Friday
(2000-3000 J/kg CAPE). Notably, mean flow is more westerly and
a bit stronger than Friday, so deep layer wind shear is a little
stronger in the 25-30 kt range. This will pose more of a large
hail risk compared to Friday as well, but damaging winds will be
the main threat with any stronger storms. Locally heavy
rainfall leading to flash flooding is also possible, but
thinking the stronger flow aloft should keep storms moving
faster and pose slightly less of a flash flood risk.

We remain in a Marginal (level 1 out of 4) Risk for excessive
rainfall from WPC. SPC has maintained the Marginal (level 1 out
of 5) Risk for severe thunderstorms for most of our area.

We look to have a weak cold frontal passage by Sunday, ushering
in slightly drier air. This combined with subtle subsidence
aloft will help briefly limit convection potential on Sunday,
though cannot completely rule out some isolated sea breeze
convection in the afternoon.

Better support for forcing aloft will return by late Monday as
mean flow shifts more westerly and mid level flow increases.
At this point though, it appears the greater threat of storms
will be to our northwest on Monday where SPC has a Marginal Risk
highlighted. Still could get some isolated storms, but Monday is
trending drier locally as the lingering lower dewpoints should
limit our instability a bit. Better moisture and instability
return by Tuesday though, along with better storm chances. With
the stronger mid level flow aloft, severe thunderstorms still
look to be a greater threat compared to flash flooding, but
these details remain unclear.

A somewhat stronger cold front looks to come through late
Tuesday or Wednesday, which will help break the excessive heat
and humidity some, but the pattern aloft may still support
diurnally driven convection.

&&

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

Today...Any restrictions in fog/stratus will clear by 13Z or
so, then VFR. Isolated to scattered thunderstorms in the
afternoon may cause localized restrictions, however confidence
on where any of this may develop is low. Opted to include PROB30
groups for TSRA at all terminals. Southwest winds increasing to
near 10 kts, with gusts near 18 kts by 18Z. High confidence in
prevailing VFR, low confidence on shower and storm details.

Tonight...Prevailing VFR, though some patchy fog may develop.
Some isolated showers and thunderstorms could linger through
06Z, but confidence on this is too low to include a TAF mention
at this time. Southwest winds near 5 kts or less. Moderate
confidence.

Outlook...

Sunday-Sunday night...VFR conditions expected.

Monday-Wednesday...Mostly VFR except restrictions possible with
afternoon/evening showers and thunderstorms.

&&

.MARINE...
No prevailing marine hazards are expected through tonight.
Southwest to south winds around 10-20 kt with seas of 2-4 feet.
A 20-40% chance of a thunderstorm this afternoon into tonight
with briefly higher winds and seas possible.

Outlook...

Sunday through Wednesday...No prevailing marine hazards
expected. Isolated storms could develop along the sea breeze
Sunday, potentially impacting the back bays or nearshore
waters. Thunderstorms possible Tuesday and Wednesday nights.

Rip Currents...

For today...Southwesterly winds continue and should increase
some to 10-20 mph. Breaking waves in the surf zone are forecast
to increase some, especially for much of the Jersey Shore, at 2
to 3 feet. Given the increasing surf and southerly winds, went
with a MODERATE risk for the development of dangerous rip
currents for most of the Jersey Shore. Breaking waves should be
a little lower and winds will have more of an offshore or shore
parallel component for the Delaware Beaches and coastal
Monmouth County, therefore went with a LOW risk for the
development of dangerous rip currents.

For Sunday...Similar conditions Sunday as today. Southwesterly
winds continue around 10-15 mph. Breaking waves in the surf
zone are forecast to remain 1 to 3 feet. Maintained the same
risk of rip currents for all coastal areas.

For specific beach forecasts, visit weather.gov/beach/phi

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT this evening for PAZ070-071-
     101>106.
NJ...Heat Advisory until 8 PM EDT this evening for NJZ008>010-
     012>015-017>020-027.
DE...Heat Advisory until 8 PM EDT this evening for DEZ001.
MD...None.
MARINE...None.

&&

DISCUSSION...Guzzo/Staarmann
AVIATION...Staarmann
MARINE...Gorse/Staarmann
Hazardous weather outlook, Aug 8, 5:34 AM EDT, 7 hours 52 minutes before
Hazardous Weather Outlook
National Weather Service Mount Holly NJ
534 AM EDT Sat Aug 8 2026

MDZ012-015-019-020-090915-
Kent MD-Queen Annes-Talbot-Caroline-
534 AM EDT Sat Aug 8 2026

This Hazardous Weather Outlook is for northeast Maryland.

.DAY ONE...Today and tonight.

There is a risk of isolated severe thunderstorms this afternoon and
evening, with potential for damaging winds and locally heavy rainfall
leading to flash flooding being the main threats.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Hot and humid conditions will persist through Tuesday along with
daily chances for showers and thunderstorms. Chances for severe
thunderstorms will return on Tuesday.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to standard operating procedures.

Staarmann

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 8, 1:44 PM EDTSevere Thunderstorm WarningPHIKent, New Castle46 min
Aug 8, 12:55 PM EDTSevere Thunderstorm WarningPHIChester50 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2026Severe Thunderstorm Warnings in Delaware, 2026Every severe thunderstorm warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.