Alert archive / Pennsylvania / Areal Flood Warnings in 2020

Areal Flood Warning 26, NWS Philadelphia/Mount Holly

August 4, 20205 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Aug 4, 2020, 2:09 PM EDT for 5 counties in Pennsylvania. It was in force for 15 hr. 47 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 4, 2020, 2:09 PM EDT (18:09 UTC)
Expired
Aug 5, 2020, 5:00 AM EDT
In force
15 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Berks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 69 km from the middle of the area, began a volume at 18:12 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.

What was reported inside it

TimeReportWhereRemark
Aug 4, 2:13 PM EDTFLOOD3 Wnw Uwchlan Twp, PAFLOODING ON STATE HIGHWAY 100 NEAR I-76. TIME BASED ON DISPATCH REPORT.
Aug 4, 2:16 PM EDTHEAVY RAIN 7.74King Of Prussia, PAREPORTED AT KING OF PRUSSIA.
Aug 4, 2:35 PM EDTHEAVY RAIN 8Skippack, PA8 INCH STORM TOTAL IN SKIPPACK.
Aug 4, 2:41 PM EDTHEAVY RAIN 4.331 Sw Willistown Twp, PAMESONET STATION AS641 WESTTOWN.
Aug 4, 2:42 PM EDTHEAVY RAIN 7.32Norristown, PAFLOODING ALONG THE SCHUYLKILL AT NORRISTOWN BEGINNING.
Aug 4, 3:00 PM EDTHEAVY RAIN 2.781 E Willow Grove, PAMESONET STATION EW1527 WILLOW GROVE.
Aug 4, 3:00 PM EDTHEAVY RAIN 2.811 Nnw Rockledge, PAMESONET STATION FW0421 WILLOW GROVE.
Aug 4, 3:00 PM EDTHEAVY RAIN 4.831 Ssw Cedarville, PAMESONET STATION EW5860 POTTSTOWN.
Aug 4, 3:00 PM EDTHEAVY RAIN 5.321 W Easttown Twp, PAMESONET STATION EW0301 BERWYN.
Aug 4, 3:00 PM EDTHEAVY RAIN 5.33Phoenixville, PAMESONET STATION EW4075 PHOENIXVILLE.
Aug 4, 3:00 PM EDTHEAVY RAIN 7.48Wayne, PAMESONET STATION CW8212 SAINT DAVIDS.
Aug 4, 3:01 PM EDTHEAVY RAIN 3.521 Nnw Lima, PAMESONET STATION FW6794 MEDIA.
Aug 4, 3:01 PM EDTHEAVY RAIN 4.57South Pottstown, PAMESONET STATION PTNP1 SOUTH POTTSTOWN.
Aug 4, 3:01 PM EDTHEAVY RAIN 5.831 Sw East Nantmeal Twp, PAMESONET STATION CW6876 GLENMOORE.
Aug 4, 3:01 PM EDTHEAVY RAIN 6.121 Sse New Hanover Twp, PAMESONET STATION FW2483 NEW HANOVER.
Aug 4, 3:02 PM EDTFLOOD2 Ne Warwick Twp, PAWIDESPREAD FLOODING ON SAINT PETERS ROAD AND SCHOOL ROAD. TIME BASED ON DISPATCH REPORT.
Aug 4, 3:09 PM EDTHEAVY RAIN 3.551 Nw Oaks, PAMESONET STATION OKELS OAKS (ES).
Aug 4, 3:09 PM EDTHEAVY RAIN 4.251 Wnw Wayne, PAMESONET STATION RTWYN WAYNE (RADNOR PW).
Aug 4, 3:09 PM EDTHEAVY RAIN 4.91Norwood, PAMESONET STATION NRWOD NORWOOD.
Aug 4, 3:09 PM EDTHEAVY RAIN 5Eagleville, PAMESONET STATION EGLVL NORRISTOWN (EAGLEVILLE ES).
Aug 4, 3:09 PM EDTHEAVY RAIN 5.391 W Wyola, PAMESONET STATION AS778 BERWYN.
Aug 4, 3:09 PM EDTHEAVY RAIN 5.811 N Bryn Mawr, PAMESONET STATION RSMHH ROSEMONT (HARRISON).
Aug 4, 3:10 PM EDTHEAVY RAIN 4.66Hatfield, PAMESONET STATION CW2718 HATFIELD.
Aug 4, 3:10 PM EDTHEAVY RAIN 4.691 Nw Conshohocken, PAMESONET STATION 6809D 1 NW CONSHOHOCKEN.
Aug 4, 3:10 PM EDTHEAVY RAIN 6.01Swarthmore, PAMESONET STATION DW9584 SWARTHMORE.
Aug 4, 3:10 PM EDTHEAVY RAIN 6.071 Ese Royersford, PAMESONET STATION FW7722 ROYERSFORD.
Aug 4, 3:10 PM EDTHEAVY RAIN 6.611 Ese Exton, PAMESONET STATION EW6163 WEST CHESTER.
Aug 4, 3:11 PM EDTHEAVY RAIN 3.331 Sse Exton, PAMESONET STATION AS680 WEST WHITELAND TWP.
Aug 4, 3:11 PM EDTHEAVY RAIN 4.09Phoenixville, PAMESONET STATION AV344 PHOENIXVILLE.
Aug 4, 3:12 PM EDTHEAVY RAIN 4.361 Nnw Oreland, PAMESONET STATION EW7157 FORT WASHINGTON.
Aug 4, 3:12 PM EDTHEAVY RAIN 7.462 Ne Lower Pottsgrove T, PAMESONET STATION FW7071 GILBERTSVILLE.
Aug 4, 3:15 PM EDTFLOODSouth Pottstown, PATHE GAUGE ON THE SCHUYLKILL RIVER IN POTTSTOWN REACHED FLOOD STAGE AT 315 PM AND CRESTED AT 15.16 FEET AT 1045 PM ON AUGUST 4.
Aug 4, 3:15 PM EDTHEAVY RAIN 2.112 Ese Willow Grove, PAMESONET STATION HNTDN 1 ESE WILLOW GROVE.
Aug 4, 3:15 PM EDTHEAVY RAIN 3.791 Nw Willow Grove, PAMESONET STATION FW1161 WILLOW GROVE.
Aug 4, 3:15 PM EDTHEAVY RAIN 4.052 Wnw Lower Pottsgrove, PAMESONET STATION PTTGR POTTSTOWN (HS).
Aug 4, 3:15 PM EDTHEAVY RAIN 4.671 Nnw East Caln Twp, PAMESONET STATION ELVPA 1 NNW EAST CALN TWP.
Aug 4, 3:15 PM EDTHEAVY RAIN 4.672 S East Goshen Twp., PAMESONET STATION AT593 WEST CHESTER.
Aug 4, 3:15 PM EDTHEAVY RAIN 5.02Worcester Twp, PAMESONET STATION CW1648 WORCESTER.
Aug 4, 3:15 PM EDTHEAVY RAIN 5.152 E Lawrence Park, PAMESONET STATION HVRTN 1 NW DREXEL HILL.
Aug 4, 3:15 PM EDTHEAVY RAIN 5.27Wyola, PAMESONET STATION NWTNS NEWTOWN SQUARE.
Aug 4, 3:15 PM EDTHEAVY RAIN 5.57Upper Providence Twp, PAMESONET STATION OKSBR UPPER PROVIDENCE TWP.
Aug 4, 3:15 PM EDTHEAVY RAIN 6.611 Ne Villanova, PAMESONET STATION VILLA VILLANOVA.
Aug 4, 3:26 PM EDTFLOOD1 Nw Upper Hanover Twp, PAAMERICAN LEGION INUNDATED BY FLOOD WATER IN EAST GREENVILLE.
Aug 4, 3:30 PM EDTFLOOD1 W Glenolden, PAFLOODING AT SOUTH AVE-MACDADE BLVD INTERSECTION.
Aug 4, 3:31 PM EDTHEAVY RAIN 8.18Wynnewood, PAREPORTED AT WYNNEWOOD PA.
Aug 4, 4:45 PM EDTHEAVY RAIN 5.12Schuylkill Twp, PA
Aug 4, 7:10 PM EDTHEAVY RAIN 8.59Wynnewood, PASTORM TOTAL RAINFALL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 6.2 hours before the alert went out and 218 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, Brookhaven, NY at 12:00Z on 2020-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1593 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, Brookhaven, NY at 12:00Z on 2020-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 150 square meters per square second.19395878Sfc1 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
1593 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
570 m above ground
0-6 km bulk shear
53 kt
0-1 km storm-relative helicity
150 m²/s²
0-3 km storm-relative helicity
245 m²/s²
Significant tornado parameter
1.5
Supercell composite
7.4

Open this sounding in Storm Lab

The text

As transmitted.

132 
WGUS41 KPHI 041809
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
209 PM EDT Tue Aug 4 2020

PAC011-029-045-091-101-050300-
/O.NEW.KPHI.FA.W.0026.200804T1809Z-200805T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
209 PM EDT Tue Aug 4 2020

The National Weather Service in Mount Holly NJ has issued a

* Flood Warning for...
  Southeastern Berks County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 1100 PM EDT Tuesday.

* At 205 PM EDT, reporting gauges indicate flooding occuring along 
  the French Creek, West and East Branches of Perkiomen, Wissahickon 
  Creek, and Pennypack Creek. Up to 5 inches of rain fell with the 
  earlier rounds of heavy rain. Any additional rain should be light. 
  However, it will take time for the runoff to recede.

* Some locations that could experience flooding include...
  Philadelphia, Camden, Norristown, Chester, Pottstown, Phoenixville,
  Lansdale, West Norriton, East Norriton, Yeadon, Conshohocken,
  Hatboro, Souderton, Folcroft, Ambler, Swarthmore, Paulsboro,
  Collegeville, Royersford and Jenkintown.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 300 and 345.
 Northeast Extension between mile markers 21 and 38.
 Interstate 95 in Pennsylvania between mile markers 6 and 33.
 Interstate 76 in Pennsylvania between mile markers 327 and 351.
 Interstate 676 in Pennsylvania between mile markers 0 and 1.
 Interstate 476 in Pennsylvania between mile markers 0 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 4045 7554 4009 7495 4006 7498 4005 7498
      4002 7501 4002 7504 3998 7508 3996 7513
      3991 7513 3988 7516 3985 7525 3985 7534
      4014 7587

$$

SFJ
3 follow-up statements
728 
WGUS41 KPHI 050235
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
1035 PM EDT Tue Aug 4 2020

PAC011-029-045-091-101-050900-
/O.EXT.KPHI.FA.W.0026.000000T0000Z-200805T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
1035 PM EDT Tue Aug 4 2020

The National Weather Service in Mount Holly NJ has extended the

* Flood Warning for...
  Southeastern Berks County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 500 AM EDT Wednesday.

* At 1030 PM EDT, runoff from today's heavy rain was keeping many 
  streams and creeks out of their banks. Flooding is expected to 
  continue overnight.

* Some locations that will continue to experience flooding include...
  Philadelphia, Camden, Norristown, Chester, Pottstown, Phoenixville,
  Lansdale, West Norriton, East Norriton, Yeadon, Conshohocken,
  Hatboro, Souderton, Folcroft, Ambler, Swarthmore, Paulsboro,
  Collegeville, Royersford and Jenkintown.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 300 and 345.
 Northeast Extension between mile markers 21 and 38.
 Interstate 95 in Pennsylvania between mile markers 6 and 33.
 Interstate 76 in Pennsylvania between mile markers 327 and 351.
 Interstate 676 in Pennsylvania between mile markers 0 and 1.
 Interstate 476 in Pennsylvania between mile markers 0 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 4045 7554 4009 7495 4006 7498 4005 7498
      4002 7501 4002 7504 3998 7508 3996 7513
      3991 7513 3988 7516 3985 7525 3985 7534
      4014 7587

$$

Iovino
913 
WGUS81 KPHI 050357
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
1157 PM EDT Tue Aug 4 2020

PAC011-045-050404-
/O.CAN.KPHI.FA.W.0026.000000T0000Z-200805T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Delaware PA-
1157 PM EDT Tue Aug 4 2020

...THE FLOOD WARNING HAS BEEN CANCELLED FOR SOUTHEASTERN BERKS AND
DELAWARE COUNTIES...

Flood waters are receding and no longer pose a threat.

LAT...LON 4025 7569 4044 7553 4009 7496 4002 7501
      4002 7504 3996 7513 3991 7513 3988 7516
      3986 7521 3988 7526 3994 7524 4006 7536
      4004 7541 4003 7540 4000 7545 3998 7544
      3995 7552 4014 7587

$$

PAC029-091-101-050900-
/O.CON.KPHI.FA.W.0026.000000T0000Z-200805T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Chester PA-Philadelphia PA-
1157 PM EDT Tue Aug 4 2020

...A FLOOD WARNING REMAINS IN EFFECT UNTIL 500 AM EDT WEDNESDAY FOR
MONTGOMERY...NORTHEASTERN CHESTER AND PHILADELPHIA COUNTIES...

At 1150 PM EDT, flooding contined in parts of southeastern 
Pennsylvania as a result of Tuesday's heavy rainfall. A number of 
rivers and creeks were in flood, including the Schuylkill River, the 
Perkiomen Creek, the French Creek, and the Wissahickon Creek.

Some locations that could continue to experience flooding include...
Philadelphia, Norristown, Pottstown, Phoenixville, Lansdale, West 
Norriton, East Norriton, Conshohocken, Hatboro, Souderton, Ambler, 
Collegeville, Royersford, Jenkintown, Narberth, Trappe and Hatfield.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 300 and 345.
 Northeast Extension between mile markers 21 and 37.
 Interstate 95 in Pennsylvania between mile markers 12 and 32.
 Interstate 76 in Pennsylvania between mile markers 327 and 351.
 Interstate 676 in Pennsylvania between mile markers 0 and 1.
 Interstate 476 in Pennsylvania between mile markers 15 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 4025 7569 4044 7553 4009 7496 4002 7501
      4002 7504 3996 7513 3991 7513 3988 7516
      3986 7521 3988 7526 3994 7524 4006 7536
      4004 7541 4003 7540 4000 7545 3998 7544
      3995 7552 4014 7587

$$

Iovino
771 
WGUS81 KPHI 050850
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
450 AM EDT Wed Aug 5 2020

PAC029-091-101-050900-
/O.EXP.KPHI.FA.W.0026.000000T0000Z-200805T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Chester PA-Philadelphia PA-
450 AM EDT Wed Aug 5 2020

...THE FLOOD WARNING WILL EXPIRE AT 500 AM EDT FOR MONTGOMERY...
NORTHEASTERN CHESTER AND PHILADELPHIA COUNTIES...

Flood waters are receding and are no longer expected to pose a 
threat to life or property. Please continue to heed any road 
closures.

LAT...LON 4025 7569 4044 7553 4009 7496 4002 7501
      4002 7504 3996 7513 3991 7513 3988 7516
      3986 7521 3988 7526 3994 7524 4006 7536
      4004 7541 4003 7540 4000 7545 3998 7544
      3995 7552 4014 7587

$$

CMS

What forecasters said that day

The local office's own words before this areal flood 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 areal flood warning went out at Aug 4, 1:16 PM EDT, 53 minutes earlier.

Area forecast discussion, Aug 4, 1:16 PM EDT, 53 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
116 PM EDT Tue Aug 4 2020

.SYNOPSIS...
Tropical Cyclone Isaias is expected to move north and reach the
Mid Atlantic later Tuesday. Isaias will move toward New England
by Wednesday. High pressure will build in to our north later
this week into this weekend while a weak front lingers to our
south.

&&

.NEAR TERM /THROUGH TONIGHT/...
Tornado Watch for the New Jersey and southeast Pennsylvania
cancelled.

Tropical Storm Warning remains in effect.

The center of Tropical Storm Isaias is lifting through the
region, and the heaviest rain is now across eastern Pennsylvania
and northern New Jersey. The tornado threat has lifted north of
the forecast area, so will cancel the Tornado Watch.

Flash flooding continues due to heavy rain of 4-6 inches with
amounts as high as 8", and rain continues.

Winds turning to the west behind departing Isaias, but remain at
Tropical Storm Force.

&&

.SHORT TERM /WEDNESDAY/...
Quieter weather for Wednesday as high pressure starts to build
in to our north. This will bring a mainly dry day with
seasonable temperatures under partly to mostly sunny skies.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A fairly typical but overall quieter summer pattern is expected
for the long term forecast. The mean upper level trough over the
east will lift out but the mid Atlantic region will remain in a
fairly moist W/SW flow regime around high pressure ridging over
the western Atlantic. This will result in chances for scattered
showers/storms most days that will be mainly diurnally driven
meaning the best chances will be in the afternoon and early
evening. Temperatures will be around average for this time of
year.

&&

.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today... A rapid deterioration in conditions is expected from
south to north soon after 12z. MVFR to IFR conditions are
expected through much of the day in association with Hurricane
Isaias. Areas of torrential rainfall with low vsbys are likely.
Strong and erratic winds are expected with a sharp change in
wind direction expected during the mid afternoon. Gusts may be
briefly higher than shown in the TAFs especially near MIV and
ACY. While confidence is low in exact details and timing,
confidence is high in the overall trend, with hazardous aviation
conditions expected for most of the area.

Tonight... Mainly VFR. Southwest winds 10 to 20 kt diminishing to 5
to 10 kt. Moderate confidence.

Outlook...

Wednesday through Saturday...Mostly VFR. Scattered SHRA/TSRA
possible each afternoon/evening that would result in brief sub-
VFR conditions at a given terminal. Fog may develop during the
overnight. West winds less than 10 kt on Wednesday, then east to
northeast Thursday through Saturday. LGT/VRB at night. Moderate
confidence.

&&

.MARINE...
Today and Tonight... Tropical Storm Warnings remain in effect as
Isaias moves north through the region. Sustained winds of 45 to
55 kts with gusts up to Hurricane force will continue. Heavy
rain and strong winds will give way to a gradual improving of
conditions later this afternoon. Seas will also build to between
12 and 18 feet over the Atlantic coastal waters. A slow
decrease in seas down towards 5 feet can be expected by
Wednesday morning.

Outlook...

Wednesday morning...Seas may linger near 5 feet on the New Jersey
coastal waters but should subside below advisory criteria by midday.

Wednesday afternoon through Saturday...Sub-advisory winds/seas
expected through the period. Chances of showers/storms through the
period, especially in the afternoon/evening hours.

Rip Currents...

On Tuesday, impacts from Isaias will increase the rip-current risk
level to high. In addition, high surf is expected. A rip
current risk statement and high surf advisory are in effect for
this period, so in conclusion Tuesday will not be a good day to
be at the beach.

The rip current risk will likely remain elevated on Wednesday.

&&

.HYDROLOGY...
Hydro concerns continue early this morning as showers/storms
continue ahead of Isaias. Any of these will be capable of
producing heavy rain with at least localized flash flooding
possible. The heaviest, steadiest rain with the storm will
arrive this morning from south to north with more widespread
flash flooding becoming a big concern during this time. Most
susecptible areas will be near and N/W of the I-95 corridor
especially since places such as in Berks County have received so
much rainfall recently. With Isaias, 3 to 6 inches of rain,
with locally higher amounts are expected. Flooding could be
widespread and significant.

In addition to flash flooding, river flooding is also expected. But
with a more consolidated area of rainfall across PA, the threat
across NJ including the Passaic and Raritan basins has lessened. The
latest MARFC forecast still has about 15 forecast points above
Action Stage and 6 at or above Flood Stage, including, Philadelphia,
Norristown, and Pottstown on the Schuylkill, Graterford on Perkiomen
Creek, Langhorne on Neshaminy Creek, and Chadds Ford and Wilmington
on the Brandywine. The latest forecast has these points cresting
later today or tonight. With such a large swath of precipitation
expected along and west of the I95 corridor, most basins in this
area will see at least some threat. That said, the Delaware River is
expected to remain within its banks.

&&

.TIDES/COASTAL FLOODING...
The coastal flooding impacts from Isaias remain very uncertain at
this time. Models notoriously handle fast-moving, intense cyclones
poorly in our area, as the short duration of onshore flow competes
with the strength of the winds. These competing impacts and
sensitivities are not well understood from a modeling standpoint,
leading to rather large spread in the model guidance.

Coastal flooding impacts are expected across the area today, with
four different regions we will be monitoring. The first, and
potentially most significant, is for the eastern shore of Chesapeake
Bay, where surge will likely move northward during the day. What is
unclear, however, is the strength of this surge. Model guidance is
particularly poor for these areas, and the output the past couple of
days seems unrealistically low. However, the extent of impacts
remains quite unclear. At this point, there is potential for
moderate flooding, which requires continuation of the coastal flood
warning. However, it is possible impacts will be less
significant/widespread. We will likely not have a better idea of
impacts until after daybreak, when gauges in lower Chesapeake Bay
begin to respond.

The second area is Delaware Bay. The real question here will be the
timing of the surge relative to the astronomical high tide.
With guidance trending a little faster with the surge, the timing
looks a little less favorable for coincidence of peak surge and
astronomical high tide for the Delaware Bay sites.
Nevertheless, the strength of southeast winds in advance of Isaias
may compensate much more readily than models suggest. A coastal
flood advisory has been issued here for the entire day given the
uncertainty of peak surge timing.

The third area is the tidal Delaware River. Here, confidence is
increasing that minor flooding will occur during the afternoon, as
predecessor southeast winds will likely combine with freshwater
runoff to lead to a period of tidal flooding from early afternoon to
early evening. As with Delaware Bay, confidence is not particularly
high on exact timing of flooding, so have issued a coastal flood
advisory for a broader period of time than normal (11 am to 8 pm).

The fourth area is the Atlantic coast. As with Delaware Bay, timing
of the strongest surge appears to occur between astronomical high
tides. However, the strength of onshore flow and exacerbating
behavior of wave runup will likely produce areas of flooding. Of
particular concern is back bays that are susceptible to southeast
flow, which can act to trap water. Barnegat Bay and Little Assawoman
Bay are particularly susceptible in these regimes, and these areas
may experience more widespread/significant flooding. Confidence is
pretty low in general for the coast, but given the very strong
onshore flow expected today, suspect at least some impacts in the
especially vulnerable spots are likely.

&&

.EQUIPMENT...
The NOAA Weather Radio All-Hazards broadcast from Hibernia Park
Pennsylvania (Station WNG-704) remains off the air.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flash Flood Watch until midnight EDT tonight for PAZ054-055-
     060>062-070-071-101>106.
     Tropical Storm Warning for PAZ070-071-101>106.
     Coastal Flood Advisory until 8 PM EDT this evening for PAZ070-
     071-106.
NJ...Flash Flood Watch until midnight EDT tonight for NJZ001-
     007>010-012>027.
     Tropical Storm Warning for NJZ001-007>010-012>027.
     Coastal Flood Advisory until 8 PM EDT this evening for
     NJZ016>019-021-023-024.
     High Rip Current Risk until midnight EDT tonight for NJZ014-
     024>026.
     Coastal Flood Advisory until 2 AM EDT Wednesday for NJZ012>014-
     020-022-025>027.
     High Surf Advisory until midnight EDT tonight for NJZ014-
     024>026.
DE...Flash Flood Watch until midnight EDT tonight for DEZ001>004.
     Tropical Storm Warning for DEZ001>004.
     Coastal Flood Advisory until 8 PM EDT this evening for
     DEZ001>004.
     High Rip Current Risk until midnight EDT tonight for DEZ004.
     High Surf Advisory until midnight EDT tonight for DEZ004.
MD...Flash Flood Watch until midnight EDT tonight for MDZ008-012-
     015-019-020.
     Tropical Storm Warning for MDZ008-012-015-019-020.
     Coastal Flood Warning until 6 AM EDT Wednesday for MDZ008-012-
     015-019-020.
MARINE...Tropical Storm Warning for ANZ430-431-450>455.
&&

Synopsis...Fitzsimmons
Near Term...Fitzsimmons/MPS
Short Term...Fitzsimmons
Long Term...Fitzsimmons/MPS
Aviation...O'Brien
Marine...CMS
Hydrology...WFO PHI
Tides/Coastal Flooding...WFO PHI
Equipment...WFO PHI
Hazardous weather outlook, Aug 4, 1:12 PM EDT, 57 minutes before
Hazardous Weather Outlook
National Weather Service Mount Holly NJ
112 PM EDT Tue Aug 4 2020

PAZ054-055-060>062-051700-
Carbon-Monroe-Berks-Lehigh-Northampton-
112 PM EDT Tue Aug 4 2020

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

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

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

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

MDZ008-012-015-019-020-051700-
Cecil-Kent MD-Queen Annes-Talbot-Caroline-
112 PM EDT Tue Aug 4 2020

...COASTAL FLOOD WARNING IN EFFECT UNTIL 6 AM EDT WEDNESDAY...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...TROPICAL STORM WARNING IN EFFECT...

This Hazardous Weather Outlook is for 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.

   Coastal Flood Warning.
   Flash Flood Watch.
   Tropical Storm Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

   Tropical Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

NJZ001-007>010-015-PAZ101>105-051700-
Sussex-Warren-Morris-Hunterdon-Somerset-Mercer-Western Chester-
Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-
112 PM EDT Tue Aug 4 2020

...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...TROPICAL STORM WARNING IN EFFECT...

This Hazardous Weather Outlook is for central New Jersey, northern
New Jersey, northwest 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.

   Flash Flood Watch.
   Tropical Storm Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

   Tropical Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

DEZ001>003-NJZ016>019-021-023-PAZ070-071-106-051700-
New Castle-Kent-Inland Sussex-Salem-Gloucester-Camden-
Northwestern Burlington-Cumberland-Cape May-Delaware-Philadelphia-
Lower Bucks-
112 PM EDT Tue Aug 4 2020

...COASTAL FLOOD ADVISORY IN EFFECT UNTIL 8 PM EDT THIS EVENING...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...TROPICAL STORM WARNING IN EFFECT...

This Hazardous Weather Outlook is for central Delaware, northern
Delaware, southern Delaware, 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.

   Flash Flood Watch.
   Coastal Flood Advisory.
   Tropical Storm Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

   Tropical Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

NJZ012-013-020-022-027-051700-
Middlesex-Western Monmouth-Ocean-Atlantic-Southeastern Burlington-
112 PM EDT Tue Aug 4 2020

...COASTAL FLOOD ADVISORY IN EFFECT UNTIL 2 AM EDT WEDNESDAY...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...TROPICAL STORM WARNING IN EFFECT...

This Hazardous Weather Outlook is for central New Jersey, northern
New Jersey 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.

   Flash Flood Watch.
   Coastal Flood Advisory.
   Tropical Storm Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

   Tropical Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

NJZ014-025-026-051700-
Eastern Monmouth-Coastal Atlantic-Coastal Ocean-
112 PM EDT Tue Aug 4 2020

...COASTAL FLOOD ADVISORY IN EFFECT UNTIL 2 AM EDT WEDNESDAY...
...HIGH SURF ADVISORY IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...HIGH RIP CURRENT RISK IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...TROPICAL STORM WARNING IN EFFECT...

This Hazardous Weather Outlook is for central New Jersey 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.

   High Rip Current Risk.
   Flash Flood Watch.
   Coastal Flood Advisory.
   High Surf Advisory.
   Tropical Storm Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

   Tropical Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

DEZ004-NJZ024-051700-
Delaware Beaches-Atlantic Coastal Cape May-
112 PM EDT Tue Aug 4 2020

...COASTAL FLOOD ADVISORY IN EFFECT UNTIL 8 PM EDT THIS EVENING...
...HIGH SURF ADVISORY IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...HIGH RIP CURRENT RISK IN EFFECT UNTIL MIDNIGHT EDT TONIGHT...
...TROPICAL STORM WARNING IN EFFECT...

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.

   High Rip Current Risk.
   Flash Flood Watch.
   Coastal Flood Advisory.
   High Surf Advisory.
   Tropical Storm Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

   Tropical Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

ANZ430-431-450>455-051700-
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 Sandy Hook to Manasquan Inlet NJ out 20 nm-
Coastal waters from Manasquan Inlet to Little Egg Inlet NJ out 20 nm-
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-
112 PM EDT Tue Aug 4 2020

...TROPICAL STORM WARNING IN EFFECT...

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.

   Tropical Storm Warning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

   Tropical Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

MPS

In the hours before

Local storm report, Aug 4, 1:54 PM EDT, 15 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
154 PM EDT TUE AUG 4 2020

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

1105 AM     TROPICAL STORM   1 WSW DOYLESTOWN        40.31N 75.15W
08/04/2020                   BUCKS              PA   TRAINED SPOTTER

            SEVERE DAMAGE AROUND THE DOYLESTOWN
            HOSPITAL. THIS DAMAGE POSSIBLY OCCURRED FROM
            A TORNADO. TIME ESTIMATED FROM RADAR.

&&

STAARMANN
Local storm report, Aug 4, 1:55 PM EDT, 14 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
155 PM EDT TUE AUG 4 2020

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

0145 PM     TROPICAL STORM   LEHIGH TWP              40.76N 75.54W
08/04/2020                   NORTHAMPTON        PA   EMERGENCY MNGR

            NUMEROUS TREES DOWN IN LEHIGH TOWNSHIP.

&&

NC
Local storm report, Aug 4, 1:59 PM EDT, 10 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
159 PM EDT TUE AUG 4 2020

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

0130 PM     TROPICAL STORM   EAST GREENVILLE         40.40N 75.50W
08/04/2020                   MONTGOMERY         PA   TRAINED SPOTTER

            LARGE BRANCH DOWN (APPROX 6 INCHES IN
            DIAMETER).

&&

NC
Local storm report, Aug 4, 2:00 PM EDT, 9 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
200 PM EDT TUE AUG 4 2020

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

1250 PM     TROPICAL STORM   1 SSE TOMS RIVER        39.94N 74.19W
08/04/2020                   OCEAN              NJ   PUBLIC

            TREES DOWN NEAR BEACHWOOD BLVD AND ROUTE 9
            IN BEACHWOOD.

&&

STAARMANN
Local storm report, Aug 4, 2:01 PM EDT, 8 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
201 PM EDT TUE AUG 4 2020

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

0201 PM     TROPICAL STORM   KEYPORT                 40.44N 74.20W
08/04/2020                   MONMOUTH           NJ   TRAINED SPOTTER

            NUMEROUS TREE LIMBS AND WIRES DOWN IN THE
            KEYPORT AREA WITH ASSOCIATED POWER OUTAGES.

&&

NC
Local storm report, Aug 4, 2:06 PM EDT, 3 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
206 PM EDT TUE AUG 4 2020

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

1200 PM     TROPICAL STORM   SOUTH BRUNSWICK         40.40N 74.54W
08/04/2020                   MIDDLESEX          NJ   LAW ENFORCEMENT

            OVER 36 TREES DOWN ACROSS SOUTH BRUNSWICK.
            NUMEROUS POWER OUTAGES AND ROADS CLOSED.

&&

STAARMANN

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 4, 5:17 AM EDTAreal Flood AdvisoryPHIBucks, Chester, Delaware, Montgomery, Philadelphia4 hr
Aug 4, 7:23 AM EDTTornado WarningPHIChester, Delaware, Montgomery, Philadelphia20 min
Aug 4, 7:28 AM EDTFlash Flood WarningPHIChester, Delaware, Montgomery3 hr
Aug 4, 8:11 AM EDTFlash Flood WarningPHIBucks, Lehigh, Montgomery, Northampton4 hr
Aug 4, 8:19 AM EDTRiver Flood WarningPHIDelaware15 hr
Aug 4, 8:19 AM EDTTornado WarningPHIBucks26 min
Aug 4, 9:23 AM EDTTornado Warning Tornado observedPHIChester22 min
Aug 4, 9:29 AM EDTTornado WarningPHIMonroe, Northampton31 min
Aug 4, 9:38 AM EDTFlash Flood WarningPHIMonroe, Northampton4 hr
Aug 4, 9:58 AM EDTTornado WarningPHIMonroe16 min
Aug 4, 10:02 AM EDTFlash Flood WarningPHIChester, Delaware4 hr
Aug 4, 10:20 AM EDTFlash Flood WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia4 hr
Aug 4, 10:51 AM EDTTornado WarningPHIMontgomery24 min
Aug 4, 11:01 AM EDTFlash Flood WarningPHIBucks4 hr
Aug 4, 11:13 AM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Northampton4 hr
Aug 4, 11:43 AM EDTFlash Flood WarningPHIBerks, Lehigh, Northampton4 hr
Aug 4, 12:06 PM EDTRiver Flood WarningPHIChester11 hr
Aug 4, 12:37 PM EDTRiver Flood WarningPHIMontgomery14 hr
Aug 4, 12:48 PM EDTRiver Flood WarningPHIChester, Delaware24 hr
Aug 4, 1:01 PM EDTRiver Flood WarningPHIBucks18 hr
Aug 4, 1:12 PM EDTRiver Flood WarningPHIBerks10 hr
Aug 4, 1:12 PM EDTRiver Flood WarningPHIMontgomery26 hr
Aug 4, 1:12 PM EDTRiver Flood WarningPHIChester, Montgomery, Philadelphia43 hr
Aug 4, 1:12 PM EDTRiver Flood WarningPHIMontgomery, Philadelphia35 hr
Aug 4, 1:59 PM EDTAreal Flood WarningPHIChester, Delaware9 hr
Aug 4, 2:23 PM EDTRiver Flood WarningPHILehigh16 hr
Aug 4, 2:47 PM EDTAreal Flood WarningPHIBucks9 hr
Aug 4, 3:42 PM EDTAreal Flood WarningPHILehigh, Northampton4 hr
Aug 4, 4:39 PM EDTRiver Flood WarningPHIMonroe6 hr
Aug 4, 7:29 PM EDTAreal Flood WarningPHILehigh, Northampton12 hr

Nearby

Areal Flood Warnings in Pennsylvania, 2020Every areal flood warning in 2020

Sources

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