Alert archive / Pennsylvania / Areal Flood Advisories in 2017

Areal Flood Advisory 85, NWS Philadelphia/Mount Holly

July 14, 20174 counties in Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jul 14, 2017, 2:14 PM EDT for 4 counties in Pennsylvania; New Castle County, Delaware. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Jul 14, 2017, 2:14 PM EDT (18:14 UTC)
Expired
Jul 14, 2017, 5:15 PM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

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

The radar

The Philadelphia radar (KDIX), 103 km from the middle of the area, began a volume at 18:14 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.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.2 hours before the alert went out and 186 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 2017-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 403 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 2017-07-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 52 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
403 J/kg
Mixed-layer CIN
-72 J/kg
Mixed-layer LCL
1367 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
52 m²/s²
0-3 km storm-relative helicity
118 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted.

326 
WGUS81 KPHI 141814
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
214 PM EDT FRI JUL 14 2017

DEC003-PAC029-045-091-101-142115-
/O.NEW.KPHI.FA.Y.0085.170714T1814Z-170714T2115Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
214 PM EDT FRI JUL 14 2017

The National Weather Service in Mount Holly NJ has issued a

* Flood Advisory for...
  Northern New Castle County in northern Delaware...
  Southeastern Montgomery County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 515 PM EDT

* At 214 PM EDT...Doppler radar indicated heavy rain due to 
  thunderstorms moving into the advisory area. This will cause minor 
  flooding in the advisory area.

* Some locations that will experience flooding include...
  Philadelphia, Camden, Wilmington, Newark, West Chester, Norristown,
  Chester, Phoenixville, West Norriton, East Norriton, Coatesville,
  Yeadon, Westtown, Downingtown, Conshohocken, Folcroft, Ambler,
  Swarthmore, Elsmere and Paulsboro.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 3976 7606 3983 7604 3987 7599 3995 7600
      4004 7593 4011 7594 4017 7582 4015 7503
      4012 7496 4005 7498 3996 7513 3990 7513
      3985 7525 3984 7536 3977 7546 3969 7551
      3970 7579 3972 7579 3972 7613

$$

SFJ

What forecasters said that day

The local office's own words before this areal flood advisory 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 areal flood advisory went out at Jul 14, 2:08 PM EDT, 6 minutes earlier.

Area forecast discussion, Jul 14, 2:08 PM EDT, 6 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
208 PM EDT Fri Jul 14 2017

.SYNOPSIS...
A cold front will move through the region tonight into Saturday
before stalling off the Carolina coast this weekend. High
pressure will build across the region this weekend. An area of
low pressure develops along the stalled boundary and starts to
move northward into our area late Monday and Tuesday. High
pressure will build into the region for Wednesday. Another cold
front will slowly drop down from the north on Thursday.

&&

.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Severe Thunderstorm Watch #414 is in effect for SE PA, including
Philadelphia, as well as S NJ, E MD and DE through 9 PM. A line
of strong storms are already starting to organize near the
differential heating boundary/stationary front in southern PA.
Strong heating south of the front has resulted in a moderately
unstable airmass with MLCAPE ranging from around 1000 J/kg in
far SE PA and adjacent S NJ to 2000+ J/kg over the mid Delmarva,
per SPC mesoanalysis. It is these areas along and south of the
warm front that will be conducive for severe thunderstorms.
Expect to see pockets of damaging winds within the line segments
that move across the Watch area. Similar to yesterday, there may
be a brief spin up with storms that track along the stationary
front, where winds are backed out of the SE and E.

Two additional headlines are in effect. A Flash Flood Watch for
portions of SE PA, S NJ, NE MD and DE through midnight. These
locations will be closest the frontal boundary, where the focus
for convection will be later this afternoon and evening. An
increasingly stable boundary layer farther north into NE PA and
N NJ will have a tough time supporting deeper convective
updrafts needed for heavy rainfall rates and flash flooding.
Poor drainage flooding is still a possibility though.

A Heat Advisory is in effect for central and southern DE and
adjacent eastern Maryland. Temperatures are close to forecast
but dewpoints are several degrees higher (mid to upper 70s vs
forecast in the low to mid 70s). Observed heat indices are in
the 100-105F range as of 2 PM this afternoon.

Discussion from this morning...
Surface analysis this morning shows a 1013 mb surface low over
Lake Ontario. A frontal boundary extends southward from the low
into central PA and then curves back eastward near the Mason-
Dixon line. This boundary did move southward as a cold front
through our area yesterday before stalling over the Delmarva
Peninsula last night. The front may drift back to the north and
east through this afternoon in response to backed flow from the
southwest ahead of the aforementioned low to our northwest.
Another very active weather day is expected for our area with
the front overhead.

The main concerns for today will be locally heavy rainfall/flooding
and severe thunderstorms. However, you can even add heat to the mix
for Delmarva.

Consideration for a Flash Flood Watch for a portion of the forecast
area will be made by midday after some of the 12Z guidance starts
to come in. A bands of locally heavy rain (1.5-2.5 inches) fell
over the past 24 hours from Berks County eastward along the
northern suburbs of Philadelphia and the I-195 corridor in
central NJ. An additional swath of enhanced rain fell last night
and early this morning just north of I-80 in NE PA and NW NJ.
Flash Flood Guidance is considerably lower (less than 2 inches
in three hours) in these locations due to the wet antecedent
conditions. While there is still uncertainty regarding where
the axis of heaviest rain sets up this afternoon and evening, it
will likely be in the vicinity of the aforementioned frontal
boundary. This would put SE PA, S NJ and Delmarva at highest
risk. Some of the guidance does hint at another band of heavier
rain farther north on the cool side of the boundary back toward
the I-78 corridor. It is important to note that just about all
of the model guidance yesterday was too far north with the
storms and axis of heaviest rainfall. This may happen again
today, so confidence for heavy rainfall that far north is
considerably lower.

SPC continues to highlight SE PA, the S half of NJ and Delmarva in a
slight risk for severe storms. Visible satellite imagery shows
s strong heating is underway south of the front from about the
Mason- Dixon line southward. This differential heating boundary
will be the focus for the development of numerous storms this
afternoon with the greater risk for severe storms residing along
and to the south of this heating boundary. This environment
will be highly conducive for damaging wet microbursts with a
delta theta-e of 25-30 C in the lowest 15-20 kft of the
atmosphere. The timing for severe weather looks to be fairly
similar to yesterday...about 4-8 PM.

There will be a notable SW to NE temperature gradient across the
region with highs ranging from only the low 70s north of the front
in the southern Poconos and NW NJ to the mid 90s south of the front
in eastern MD and interior southern Delaware. Expect differential
heating near this front (breaks in the clouds leading to strong
heating south of the front) to produce an impressive temperature
gradient in a short distance (10+ degree temperature difference
within 20 or 30 miles) around the greater Philadelphia metro and
coastal NJ. With dewpoints in the 70s, heat indices look to
peak in the 100-103F range for mid Delmarva. Any higher heat
index values would warrant a Heat Advisory.

&&

.SHORT TERM /MIDNIGHT THROUGH 6 AM SATURDAY/...
The showers and thunderstorms will likely be ongoing in our
region this evening with a continuing threat of heavy rain and
strong winds. The precipitation is forecast to pass off the
coast during the overnight hours but clouds and patchy fog
should linger for much of the late night period.

A mesoscale low is expected to develop around northern Virginia
and Maryland late today and it should pass off the New Jersey
coast overnight. A cold front approaching from the northwest is
anticipated to arrive toward daybreak.

The wind should become light and variable for much of the
night, settling into the northwest around 5 to 10 MPH with the
arrival of the cold front. Minimum temperatures are expected to
favor the middle 60s to the lower 70s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Saturday and Sunday...The cold front drops south and east of
the area on Saturday and stalls off the Carolina coast, where it
remains through the weekend. Weak high pressure will build into
our area for the weekend, keeping us dry for at least a couple
of days. Might be a bit cloudy to start the weekend off but
overall skies will become mostly to partly sunny across the
region. With drier air in place, it should feel pretty
comfortable outside even with highs reaching into the mid to
upper 80s.

Monday through Tuesday...A low pressure system will develop
along the stalled boundary to our south and will start to move
northward on Monday. The models continue to show the low moving
up through Virginia on Monday and then into Delmarva and through
southern New Jersey on Tuesday. The low then pushes to the
north and east of our area late Tuesday into Wednesday. A chance
for showers and thunderstorms will exist as the surface low
makes its way into our area. A surface trough also develops
across our area again and this would provide a good source of
lift, promoting convective activity. In addition, an upper level
trough will build across the Mid- Atlantic. This will help to
deepen the southerly flow into our region as the atmosphere
becomes more unstable. Best timing for convection, at this
juncture, looks to be mainly during the afternoon and evening
hours.

Wednesday through Thursday...High pressure will build in behind
the departing low with clearing expected for Wednesday. The
upper trough slides to the east during this time. A cold front
will start to drop down from the north on Thursday. As the high
builds in, we will see a return to more of a west to southwest
flow, ushering in some warmer, and moister, air to the region.
Highs will start to creep back up and into the upper 80s to
lower 90s by Wednesday and then into the l ow to mid 90s for
Thursday. Increasing moisture will also mean increased humidity
across the area. Seems reasonable that some showers and
thunderstorms may develop during the afternoon and evening on
both days but location of activity is too difficult to pinpoint
this far out.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

It is a very challenging aviation weather forecast for today
with showers this morning, followed by another round of showers
and storms mid to late afternoon and evening. Timing of the
showers and thunderstorms is a low confidence forecast.
Temporary restrictions in visibility below 1 SM is possible with
these storms as they contain heavy rain. Locally strong wind
gusts are also possible with a few storms, especially farther
south and west toward RDG, PHL, ILG and MIV.

CIGs are also a challenge as they lower quickly from NE to SW
from VFR (ILG, MIV) to MVFR (PHL) to IFR (RDG, ABE) to LIFR
(TTN, PNE). Expect this to continue today with some gradual
improvement (perhaps more than gradual around RDG and Philly
terminals later this morning as a warm front lifts to the N/E).

A light winds over the area varies from NE to across ACY to E
along the I-95 terminals to S at RDG.

Variable flight conditions are forecast to persist through the
nighttime hours. The wind is expected to become light and
variable for tonight and patchy fog may develop.

OUTLOOK...
Saturday...VFR conditions expected. West winds around 10 knots.

Sunday...VFR conditions expected. Light northwest winds early,
becoming south to southeast around 10 knots or less.

Monday and Tuesday...Mainly VFR conditions expected. Afternoon
showers and thunderstorms with MVFR or lower conditions
possible. South to southeast winds around 10 knots.

&&

.MARINE...
A stalled frontal boundary is forecast will remain over our
southern waters through this afternoon with a cold front
approaching from the northwest late tonight.

The wind on the coastal waters of New Jersey and Delaware is
expected to settle into the east and southeast around 10 knots
for today and it should become south to southwest for tonight as
the cold front approaches.

Wave heights will favor 3 to 4 feet on our ocean waters today
and tonight and they should be 1 to 3 feet on Delaware Bay.

The main concern for today is strong thunderstorms with the risk
greatest in the DE Bay and southern coastal waters from mid
afternoon through mid evening (3:30-10 PM). A Severe
Thunderstorm Watch is in effect for the coastal waters from
Little Egg Inlet to Fenwick Island through 9 PM. Numerous SMWs
could be needed for convective wind gusts in excess of 34 kt.

OUTLOOK...
Saturday through Tuesday...Sub-Small Craft Advisory conditions
are expected on the area waters through Tuesday. Locally strong
winds may accompany thunderstorms on Monday and Tuesday.

RIP CURRENTS...
There is a low risk for the development of dangerous rip
currents along the coasts of New Jersey and Delaware today.

A low risk is anticipated again for Saturday.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flash Flood Watch until midnight EDT tonight for PAZ060-070-
     071-101>104.
NJ...Flash Flood Watch until midnight EDT tonight for NJZ016>018-
     021>025.
DE...Flash Flood Watch until midnight EDT tonight for DEZ001-002.
     Heat Advisory until 8 PM EDT this evening for DEZ002-003.
MD...Flash Flood Watch until midnight EDT tonight for MDZ008-012-
     015.
     Heat Advisory until 8 PM EDT this evening for MDZ012-015-019-
     020.
MARINE...None.

&&

Synopsis...Meola
Near Term...Klein
Short Term...Iovino
Long Term...Meola
Aviation...Iovino/Klein/Meola
Marine...Iovino/Klein/Meola
Hazardous weather outlook, Jul 14, 1:49 PM EDT, 25 minutes before
Hazardous Weather Outlook
National Weather Service Mount Holly NJ
149 PM EDT Fri Jul 14 2017

PAZ060-103-104-151800-
Berks-Western Montgomery-Eastern Montgomery-
149 PM EDT Fri Jul 14 2017

...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...

This Hazardous Weather Outlook is for east central Pennsylvania and
southeast Pennsylvania.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flash Flood Watch.

Some thunderstorms this afternoon and evening may be severe. The
primary hazard is expected to be strong damaging wind.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

DEZ002-MDZ012-015-151800-
Kent-Kent MD-Queen Annes-
149 PM EDT Fri Jul 14 2017

...HEAT ADVISORY IN EFFECT UNTIL 8 PM EDT THIS EVENING...
...SEVERE THUNDERSTORM WATCH 414 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...

This Hazardous Weather Outlook is for central Delaware and
northeast Maryland.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Heat Advisory.
   Severe Thunderstorm Watch.
   Flash Flood Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

DEZ001-MDZ008-NJZ016>018-021>023-PAZ070-071-101-102-151800-
New Castle-Cecil-Salem-Gloucester-Camden-Cumberland-Atlantic-
Cape May-Delaware-Philadelphia-Western Chester-Eastern Chester-
149 PM EDT Fri Jul 14 2017

...SEVERE THUNDERSTORM WATCH 414 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...

This Hazardous Weather Outlook is for northern Delaware, northeast
Maryland, southern New Jersey and southeast Pennsylvania.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.
   Flash Flood Watch.

Some thunderstorms this afternoon and evening may be severe. The
primary hazard is expected to be strong damaging wind.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

NJZ015-PAZ105-106-151800-
Mercer-Upper Bucks-Lower Bucks-
149 PM EDT Fri Jul 14 2017

This Hazardous Weather Outlook is for central New Jersey and
southeast Pennsylvania.

.DAY ONE...This Afternoon and Tonight.

Some thunderstorms this afternoon and evening may be severe. The
primary hazard is expected to be strong damaging wind. Heavy rain
leading to localized flooding is also possible.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

DEZ003-MDZ019-020-151800-
Inland Sussex-Talbot-Caroline-
149 PM EDT Fri Jul 14 2017

...HEAT ADVISORY IN EFFECT UNTIL 8 PM EDT THIS EVENING...
...SEVERE THUNDERSTORM WATCH 414 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for southern Delaware and
northeast Maryland.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Heat Advisory.
   Severe Thunderstorm Watch.

Some thunderstorms this afternoon and evening may produce heavy rain
leading to localized flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

DEZ004-NJZ019-020-027-151800-
Delaware Beaches-Northwestern Burlington-Ocean-
Southeastern Burlington-
149 PM EDT Fri Jul 14 2017

...SEVERE THUNDERSTORM WATCH 414 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for southern Delaware and
southern New Jersey.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

Some thunderstorms may produce heavy rain leading to localized
flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

NJZ014-151800-
Eastern Monmouth-
149 PM EDT Fri Jul 14 2017

This Hazardous Weather Outlook is for central New Jersey.

.DAY ONE...This Afternoon and Tonight.

There is now a moderate risk for the formation of dangerous rip
currents this afternoon and evening.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

NJZ026-151800-
Coastal Ocean-
149 PM EDT Fri Jul 14 2017

...SEVERE THUNDERSTORM WATCH 414 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for southern New Jersey.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

Some thunderstorms may produce heavy rain leading to localized
flooding.

There is now a moderate risk for the formation of dangerous rip
currents this afternoon and evening.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

NJZ024-025-151800-
Atlantic Coastal Cape May-Coastal Atlantic-
149 PM EDT Fri Jul 14 2017

...SEVERE THUNDERSTORM WATCH 414 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...

This Hazardous Weather Outlook is for southern New Jersey.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.
   Flash Flood Watch.

There is now a moderate risk for the formation of dangerous rip
currents this afternoon and evening.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

NJZ001-007>010-012-013-PAZ054-055-061-062-151800-
Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-
Carbon-Monroe-Lehigh-Northampton-
149 PM EDT Fri Jul 14 2017

This Hazardous Weather Outlook is for central New Jersey, northern
New Jersey, northwest New Jersey, east central Pennsylvania and
northeast Pennsylvania.

.DAY ONE...This Afternoon and Tonight.

Widespread hazardous weather is not anticipated.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

ANZ430-431-452>455-151800-
Delaware Bay waters north of East Point NJ to Slaughter Beach DE-
Delaware Bay waters south of East Point NJ to Slaughter Beach DE-
Coastal waters from Little Egg Inlet to Great Egg Inlet NJ out 20 nm-
Coastal waters from Great Egg Inlet to Cape May NJ out 20 nm-
Coastal waters from Cape May NJ to Cape Henlopen DE out 20 nm-
Coastal waters from Cape Henlopen to Fenwick Island DE out 20 nm-
149 PM EDT Fri Jul 14 2017

...SEVERE THUNDERSTORM WATCH 414 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for Atlantic coastal waters and
Delaware Bay Waters.

.DAY ONE...This Afternoon and Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

ANZ450-451-151800-
Coastal waters from Sandy Hook to Manasquan Inlet NJ out 20 nm-
Coastal waters from Manasquan Inlet to Little Egg Inlet NJ out 20 nm-
149 PM EDT Fri Jul 14 2017

This Hazardous Weather Outlook is for Atlantic coastal waters.

.DAY ONE...This Afternoon and Tonight.

Some thunderstorms today through tonight will be capable of
producing strong winds in excess of 34 knots.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.

In the hours before

Special weather statement, Jul 14, 9:02 AM EDT, 5 hours 12 minutes before
Special Weather Statement
National Weather Service Mount Holly NJ
902 AM EDT FRI JUL 14 2017

DEZ001-MDZ008-NJZ016-PAZ070-101-102-141330-
New Castle-Cecil-Salem-Delaware-Western Chester-Eastern Chester-
902 AM EDT FRI JUL 14 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN NEW CASTLE...
NORTHEASTERN CECIL...NORTHWESTERN SALEM...SOUTH CENTRAL CHESTER AND
SOUTHWESTERN DELAWARE COUNTIES...

At 901 AM EDT, a strong thunderstorm was located over West Grove, or
10 miles north of Newark, moving east at 25 mph.

Winds up to 30 mph are possible with this storm.

Locations impacted include...
Wilmington, Newark, Pennsville, Carneys Point, Elsmere, Kennett
Square, New Castle, Penns Grove, West Grove, Newport, Arden, Stanton,
North Star, Talleyville, Wilmington Manor, Elam, Pike Creek, Glen
Westover, Ashland and Greenville.

Brief torrential rainfall is also occurring with this storm, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3993 7587 3984 7541 3960 7554 3960 7555
      3962 7557 3966 7552 3969 7551 3971 7549
      3972 7551 3967 7555 3962 7562 3976 7595
TIME...MOT...LOC 1301Z 290DEG 23KT 3982 7583

SFJ
Special weather statement, Jul 14, 9:23 AM EDT, 4 hours 51 minutes before
Special Weather Statement
National Weather Service Mount Holly NJ
923 AM EDT FRI JUL 14 2017

DEZ001-MDZ008-PAZ101-102-141400-
New Castle-Cecil-Western Chester-Eastern Chester-
923 AM EDT FRI JUL 14 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN NEW CASTLE...
NORTHERN CECIL AND SOUTHWESTERN CHESTER COUNTIES...

At 923 AM EDT, a strong thunderstorm was located over Richardsmere,
or 10 miles north of Havre De Grace, moving east at 25 mph.

Winds up to 40 mph are possible with this storm.

Locations impacted include...
Newark, Elkton, Calvert, Oxford, North East, Rising Sun, Charlestown,
Glen Roy, Zion, Blake, Barksdale, West Nottingham, Octoraro,
Brantwood, Fair Hill, Glen Westover, Bay View, Lombard, Richardsmere
and Woodlawn.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3979 7604 3980 7573 3953 7577
      3959 7611 3965 7616 3968 7621 3972 7621
TIME...MOT...LOC 1323Z 275DEG 22KT 3969 7612

SFJ
Special weather statement, Jul 14, 1:58 PM EDT, 16 minutes before
Special Weather Statement
National Weather Service Mount Holly NJ
158 PM EDT FRI JUL 14 2017

MDZ008-PAZ060-101>104-141900-
Cecil-Eastern Montgomery-Western Montgomery-Western Chester-Eastern
Chester-Berks-
158 PM EDT FRI JUL 14 2017

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHWESTERN CECIL...
SOUTHERN BERKS...SOUTHERN MONTGOMERY...CHESTER AND NORTHERN DELAWARE
COUNTIES...

At 158 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Railroad to near Safe Harbor to
Honey Brook. Movement was east at 35 mph.

Wind gusts up to 40 mph and pea size hail are possible with these
storms.

Heavy rainfall is also occurring with these storms...and may cause
ponding on roadways and poor drainage areas. Do not drive your
vehicle through flooded roadways.

Frequent lightning is occurring with these storms. Lightning can
strike 15 miles away from a thunderstorm. If you see lightning or
hear thunder seek a safe shelter inside a building or vehicle.

Locations impacted include...
West Chester, Calvert, Norristown, Phoenixville, West Norriton, East
Norriton, Coatesville, Westtown, Downingtown, Ambler, Kennett Square,
Collegeville, Oxford, Royersford, Parkesburg, Trappe, West Grove,
Rising Sun, Honey Brook and Elverson.

LAT...LON 3972 7623 3973 7610 3976 7606 3985 7602
      3987 7599 3994 7598 3995 7600 4004 7593
      4011 7594 4014 7588 4021 7598 4020 7512
      4005 7540 3999 7545 3959 7611
TIME...MOT...LOC 1758Z 268DEG 29KT 3969 7672 3992 7632 4010 7594

Robertson

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 13, 8:17 PM EDTSpecial Weather StatementPHIMontgomery, Philadelphia43 min
Jul 14, 7:21 AM EDTAreal Flood AdvisoryPHICarbon, Monroe, Northampton3 hr
Jul 14, 11:40 AM EDTFlash Flood WatchPHIBerks, Chester, Delaware, Montgomery, Philadelphia11 hr
Jul 14, 12:30 PM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Montgomery, Northampton4 hr
Jul 14, 1:58 PM EDTSpecial Weather StatementPHIChester62 min
Jul 14, 2:31 PM EDTSevere Thunderstorm WarningPHIChester, Delaware59 min
Jul 14, 2:53 PM EDTFlash Flood WarningPHIChester, Delaware, Montgomery, Philadelphia3 hr
Jul 14, 2:57 PM EDTAreal Flood AdvisoryPHIBucks, Montgomery3 hr
Jul 14, 3:18 PM EDTSevere Thunderstorm WarningPHIChester, Delaware12 min
Jul 14, 3:23 PM EDTSevere Thunderstorm WarningPHIChester, Delaware67 min
Jul 13, 8:09 PM EDTSpecial Weather StatementPHIKent36 min
Jul 13, 8:29 PM EDTSpecial Weather StatementPHIKent31 min
Jul 13, 10:03 PM EDTSpecial Weather StatementPHISussex27 min
Jul 13, 10:15 PM EDTAreal Flood AdvisoryPHIKent, Sussex4 hr
Jul 13, 10:39 PM EDTSevere Thunderstorm WarningPHISussex51 min
Jul 14, 9:02 AM EDTSpecial Weather StatementPHINew Castle28 min
Jul 14, 12:06 PM EDTHeat AdvisoryPHIKent, Sussex7 hr
Jul 14, 3:25 PM EDTAreal Flood AdvisoryPHINew Castle4 hr
Jul 14, 3:34 PM EDTFlash Flood WarningPHINew Castle3 hr
Jul 14, 3:54 PM EDTSevere Thunderstorm WarningPHIKent, New Castle66 min
Jul 14, 5:14 PM EDTAreal Flood AdvisoryPHIKent3 hr
Jul 14, 5:24 PM EDTSpecial Weather StatementPHISussex36 min
Jul 14, 5:30 PM EDTRiver Flood WarningPHINew Castle7 hr
Jul 14, 5:40 PM EDTSevere Thunderstorm WarningPHIKent65 min
Jul 14, 5:51 PM EDTSpecial Weather StatementPHISussex39 min
Jul 14, 6:10 PM EDTFlash Flood WarningPHIKent3 hr
Jul 14, 6:20 PM EDTSevere Thunderstorm WarningPHIKent, Sussex40 min
Jul 14, 6:32 PM EDTAreal Flood AdvisoryPHISussex4 hr
Jul 14, 6:48 PM EDTSpecial Weather StatementPHISussex42 min
Jul 14, 7:15 PM EDTSevere Thunderstorm WarningPHISussex60 min

Nearby

Areal Flood Advisories in Pennsylvania, 2017Areal Flood Advisories in Delaware, 2017Every areal flood advisory in 2017

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.