Special Weather Statement, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
355 PM EDT Sat Aug 11 2018

.SYNOPSIS...
A stationary frontal boundary will remain in place across the region
through the beginning of next week. A series of disturbances will
interact with this boundary to produce unsettled weather during this
period. A low pressure system will develop and move northeastward
pushing the front out to sea on Tuesday giving way to drier weather
Wednesday and Thursday. Another frontal system will approach the
region from the west by the end of the week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Very complicated and unsettled weather pattern this afternoon and
this evening across the area. Two frontal boundaries are in place
across the east coast this afternoon. One is located offshore of the
New Jersey coast, southward across Delaware and Maryland. Another is
slowly sagging toward the area from the northwest. The fronts will
not move significantly through tonight and end up stalling across
the east coast. In between the two, widespread showers and
thunderstorms have developed this afternoon with daytime instability
and multiple short wave/vorticity impulses moving across the area.
CAPE values built to 1,000-2,000 J/kg across much of the area, with
even higher values across areas farther south. There remains little
in the way of bulk shear across the area, so widespread severe
thunderstorms are not expected. However, with the instability, any
storms that build tall enough could produce some locally gusty winds.

The main concern going through the remainder of the afternoon into
this evening will be the potential for heavy rain and slow
moving/training storms. PW values remain near 2 inches, and the flow
aloft remains weak. So storm motions will overall not be very quick
moving, so heavy rainfall accumulations is possible for some areas.
The Flash Flood Watch remains in effect for those areas where it was
previously, although even those areas not in the Watch could still
experience heavy rain at times this afternoon and evening.

The heaviest of the rain is expected to end later this evening and
toward midnight as the strong short wave/vorticity impulses move to
our northeast. There will still remain a chance of scattered showers
or thunderstorms during the overnight as the air remains very moist.
There may also be some patchy fog/stratus develop late tonight and
toward daybreak Sunday as well due to the added moisture from the
rainfall, light winds, and possible scattered clearing.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Any fog/stratus is expected to begin lifting after sunrise, but may
take a couple of hours to completely burn off/lift. After that
showers and thunderstorms are likely to develop across the area
again during the day Sunday. The frontal boundaries are expected to
remain nearly stationary across the east coast during the day
Sunday. Waves of low pressure are expected to develop along the
front and move toward the area, while several short wave/vorticity
impulses move across the area as well. The short waves are not
forecast to be as strong as Saturday, so the showers and
thunderstorms may not be as widespread. However, with PW values
remaining just below 2 inches, any showers/thunderstorms could
produce locally heavy rainfall.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Sunday night through Monday night...
An upper low is expected to cutoff and become nearly stationary
over the OH-PA-WV border Sunday night through Monday night. At
the surface, models generally keep the quasi-stationary front
near the northern Mid- Atlantic coast as the boundary meanders
somewhere between the I-95 corridor and the coast waters during
this time. The exact location of this boundary will be important
as this will likely be the focus for organized convection and
heavy rainfall once again early next week. Owing to the stagnant
synoptic pattern and prolonged risk of heavy rainfall, it's a
bit challenging to narrow down the time window when the risk for
flash flooding will be greatest. With that said, there is
particular concern for another episode of at least localized
flash flooding during peak heating hours Monday (late morning
thru mid evening). We will continue to highlight this potential
hazard in the HWO and may eventually issue yet another Flash
Flood Watch.

Tuesday through Saturday...
Tuesday begins with a closed upper low progressing slowly
northeastward over Pennsylvania. This low begins to open and
eject toward New England by late Wednesday as a shortwave passes
quickly eastward across eastern Canada. As it does so, a weak
surface low will develop and move northeastward toward New
England which will push the nearly stationary frontal boundary
out to sea. Given the expected location of the low pressure
system just to our north and west, went ahead and pushed PoPs to
low-end likely for our northern and western-most counties on
Tuesday with chance PoPs elsewhere. Expecting coverage of
showers and thunderstorms to be the greatest in these areas.

After the boundary moves out to sea, precip chances diminish
significantly through mid-week, especially Wednesday, as brief upper
ridging passes over the area. Temperatures should generally remain a
few degrees above normal for the period. Expect highs in the upper
80s south and lower 80s toward the northwest with lows in the lower
70s south and mid 60s toward the north and west. A shortwave trough
and accompanying surface low and cold front look to approach the
area by late next week from the Great lakes region. This will bring
the return for diurnal showers and thunderstorms for Friday and
Saturday.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

This afternoon and Tonight...Showers and thunderstorms will continue
to develop across the area through this afternoon into this evening.
Heavy rainfall will occur and likely reduce visibilities to IFR.
Ceilings will remain VFR, or MVFR with heaviest showers or
thunderstorms.

Thunderstorms are expected to diminish after sunset, and widespread
shower activity is expected to diminish by 05z. Once showers end,
some fog/stratus may develop late tonight into early morning Sunday
and reduce conditions to MVFR, or IFR in some locations.

Winds will be variable in and around thunderstorms, but the overall
flow is expected to be from the east to southeast around 5-10 knots,
then becoming light and variable overnight.

Sunday...Fog and stratus may begin the day across much of the area,
but will begin to lift and dissipate after sunrise Sunday. Then
VFR conditions are expected for much of the day. However, there
is a chance of showers and thunderstorms, especially during the
afternoon, which could temporarily lead to lower conditions.
Winds on Sunday are expected to be from the east around 5-10
knots.

OUTLOOK...

Sunday night through Tuesday...Variable conditions though VFR should
generally prevail outside of showers and storms. However, with
numerous rounds of showers and storms expected, temporary MVFR or
IFR restrictions possible when terminals experience a direct impact
from convection. Additionally, a more extended period of MVFR CIGs
in low clouds and fog are possible both Sunday night and Monday
night. Winds speeds will be light with a variable direction (E-NE
Sunday night, becoming S-SE Monday afternoon or night and then W on
Tuesday. Low confidence with timing of restrictions from showers and
storms.

Tuesday night through Thursday... General improvement to VFR Tuesday
night. Showers and storms return to the forecast Thursday,
particularly late in the day and over western terminals. W winds 5-
15 kt, becoming S-SW 5-10 kt on Thursday. Moderate confidence.

&&

.MARINE...
Conditions expected to remain below advisory levels tonight through
Sunday, although winds could gust around 20 knots at times this
afternoon and tonight.

Showers/thunderstorms are expected, which will lead to locally
higher winds and waves.

OUTLOOK...

Sunday night through Thursday...Winds and seas generally below SCA
criteria. However, locally higher winds and seas possible with
storms Sunday night through Tuesday.

Rip Currents...

There is a low risk for the development of dangerous rip
currents at New Jersey and Delaware beaches through the
remainder of the weekend.

&&

.TIDES/COASTAL FLOODING...
The combination of the new moon and astronomically higher tides
will result in widespread minor coastal flooding tonight. The
main threat will occur with the high tide cycles this evening
and tonight upper Delaware Bay and tidal Delaware River, which
is the higher of the two tide cycles. A Coastal Flood Advisory
remains in effect for all coastal areas, the NJ and DE
oceanfront, the back bays, Raritan Bay, Delaware Bay, and the
tidal Delaware River due to the widespread minor coastal
flooding anticipated tonight.

There remains the potential for minor coastal flooding with the
evening high tide cycles at least Sunday night, and possibly
Monday night as well.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flash Flood Watch until 1 AM EDT Sunday for PAZ054-055-060>062-
     070-071-101>106.
     Coastal Flood Advisory from 1 AM to 5 AM EDT Sunday for PAZ070-
     071-106.
NJ...Flash Flood Watch until 1 AM EDT Sunday for NJZ001-007>010-
     012>022-025>027.
     Coastal Flood Advisory from 7 PM this evening to 1 AM EDT
     Sunday for NJZ012>014-020>027.
     Coastal Flood Advisory from 10 PM this evening to 2 AM EDT
     Sunday for NJZ016.
     Coastal Flood Advisory from 1 AM to 5 AM EDT Sunday for NJZ015-
     017>019.
DE...Flash Flood Watch until 1 AM EDT Sunday for DEZ001-002.
     Coastal Flood Advisory from 7 PM this evening to 1 AM EDT
     Sunday for DEZ002>004.
     Coastal Flood Advisory from 10 PM this evening to 2 AM EDT
     Sunday for DEZ001.
MD...Flash Flood Watch until 1 AM EDT Sunday for MDZ008-012-015.
MARINE...None.

&&

Synopsis...Staarmann
Near Term...Robertson
Short Term...Robertson
Long Term...Klein/Staarmann
Aviation...Klein/Robertson
Marine...Klein/Robertson
Tides/Coastal Flooding...

Hazardous Weather Outlook
National Weather Service Mount Holly NJ
433 AM EDT Sat Aug 11 2018

NJZ001-007>010-PAZ054-055-060>062-101>105-120845-
Sussex-Warren-Morris-Hunterdon-Somerset-Carbon-Monroe-Berks-Lehigh-
Northampton-Western Chester-Eastern Chester-Western Montgomery-
Eastern Montgomery-Upper Bucks-
433 AM EDT Sat Aug 11 2018

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...

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

.DAY ONE...Today 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...Sunday through Friday.

Heavy rain with any showers and thunderstorms could lead to
localized flooding Sunday and Monday.

.SPOTTER INFORMATION STATEMENT...

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

NJZ015-017>019-PAZ070-071-106-120845-
Mercer-Gloucester-Camden-Northwestern Burlington-Delaware-
Philadelphia-Lower Bucks-
433 AM EDT Sat Aug 11 2018

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...
...COASTAL FLOOD ADVISORY IN EFFECT FROM 1 AM TO 5 AM EDT SUNDAY...

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

.DAY ONE...Today 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.

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

Minor tidal flooding is possible around the time of the evening high
tide on Sunday.

Heavy rain with any showers and thunderstorms could lead to
localized flooding Sunday and Monday.

.SPOTTER INFORMATION STATEMENT...

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

DEZ001-NJZ016-120845-
New Castle-Salem-
433 AM EDT Sat Aug 11 2018

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...
...COASTAL FLOOD ADVISORY IN EFFECT FROM 10 PM THIS EVENING TO 2 AM
EDT SUNDAY...

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

.DAY ONE...Today 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.

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

Minor tidal flooding is possible around the time of the evening high
tide on Sunday.

Heavy rain with any showers and thunderstorms could lead to
localized flooding Sunday and Monday.

.SPOTTER INFORMATION STATEMENT...

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

NJZ012>014-120845-
Middlesex-Western Monmouth-Eastern Monmouth-
433 AM EDT Sat Aug 11 2018

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...
...COASTAL FLOOD ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO 1 AM
EDT SUNDAY...

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

.DAY ONE...Today 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.

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

Minor tidal flooding is possible around the time of the evening high
tide on Sunday.

Heavy rain with any showers and thunderstorms could lead to
localized flooding Sunday and Monday.

.SPOTTER INFORMATION STATEMENT...

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

DEZ002>004-NJZ020>027-120845-
Kent-Inland Sussex-Delaware Beaches-Ocean-Cumberland-Atlantic-
Cape May-Atlantic Coastal Cape May-Coastal Atlantic-Coastal Ocean-
Southeastern Burlington-
433 AM EDT Sat Aug 11 2018

...COASTAL FLOOD ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO 1 AM
EDT SUNDAY...

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

.DAY ONE...Today 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 Advisory.

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

Minor tidal flooding is possible around the time of the evening high
tide on Sunday.

Heavy rain with any showers and thunderstorms could lead to
localized flooding Sunday and Monday.

.SPOTTER INFORMATION STATEMENT...

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

MDZ008-012-015-019-020-120845-
Cecil-Kent MD-Queen Annes-Talbot-Caroline-
433 AM EDT Sat Aug 11 2018

This Hazardous Weather Outlook is for northeast Maryland.

.DAY ONE...Today and Tonight.

The probability of widespread hazardous weather is low.

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

Heavy rain with any showers and thunderstorms could lead to
localized flooding Sunday and Monday.

.SPOTTER INFORMATION STATEMENT...

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

ANZ430-431-450>455-120845-
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-
433 AM EDT Sat Aug 11 2018

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

.DAY ONE...Today and Tonight.

The probability for widespread hazardous weather is low.

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

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.

CMS

Special Weather Statement
National Weather Service Mount Holly NJ
258 PM EDT SAT AUG 11 2018

NJZ016-021-111945-
Salem-Cumberland-
258 PM EDT SAT AUG 11 2018

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN CUMBERLAND AND EAST
CENTRAL SALEM COUNTIES...

At 258 PM EDT, a strong thunderstorm was located over Fairton, or
over Bridgeton, moving northeast at 15 mph.

Winds up to 45 mph are possible with this storm.

This storm will be near...
  Millville around 315 PM EDT.
  Seabrook Farms around 325 PM EDT.
  Rosenhayn around 335 PM EDT.
  Olivet and South Vineland around 340 PM EDT.
  Vineland around 345 PM EDT.

Other locations impacted by this storm include Centerton.

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

Frequent cloud to ground lightning is also occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3936 7517 3934 7519 3937 7523 3936 7524
      3938 7526 3940 7529 3960 7513 3942 7490
TIME...MOT...LOC 1858Z 222DEG 12KT 3940 7523

JRK

Special Weather Statement
National Weather Service Mount Holly NJ
313 PM EDT SAT AUG 11 2018

NJZ007-009-PAZ061-062-105-112000-
Hunterdon-Warren-Upper Bucks-Lehigh-Northampton-
313 PM EDT SAT AUG 11 2018

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT CENTRAL HUNTERDON...
SOUTHWESTERN WARREN...SOUTHEASTERN LEHIGH...NORTHWESTERN BUCKS AND
SOUTHEASTERN NORTHAMPTON COUNTIES...

At 312 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Zionsville to near Revere. Movement
was northeast at 15 mph.

Winds up to 45 mph and pea size hail are possible with these storms.

Locations impacted include...
Allentown, Easton, Bethlehem, Emmaus, Quakertown, Wilson, Bedminster,
Hellertown, Flemington, Tinicum, High Bridge, Clinton, Alpha, Glen
Gardner, Ferndale, Hampton, Frenchtown, Lebanon, West Easton and
Milford.

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

Frequent cloud to ground lightning is also occurring with these
storms. Lightning can strike 10 miles away from a thunderstorm. Seek
a safe shelter inside a building or vehicle.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 4064 7473 4046 7492 4040 7528 4035 7537
      4047 7557 4055 7552 4065 7532 4070 7513
      4070 7485
TIME...MOT...LOC 1912Z 211DEG 11KT 4047 7546 4053 7512

JRK

Special Weather Statement
National Weather Service Mount Holly NJ
324 PM EDT SAT AUG 11 2018

NJZ017-021>025-112015-
Coastal Atlantic-Cumberland-Atlantic-Atlantic Coastal Cape May-Cape
May-Gloucester-
324 PM EDT SAT AUG 11 2018

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT ATLANTIC...EASTERN
CUMBERLAND...SOUTHERN GLOUCESTER AND NORTHERN CAPE MAY COUNTIES...

At 324 PM EDT, radar indicated strong thunderstorms were located
along a line extending from Dividing Creek to near Marmora. Movement
was northeast at 20 mph.

Winds up to 45 mph and pea size hail are possible with these storms.

Locations impacted include...
Vineland, Atlantic City, Millville, Ocean City, Cumberland,
Pleasantville, Somers Point, Ventnor City, Brigantine, Northfield,
Absecon, Margate City, Buena, Egg Harbor City, Laurel Lake, Weymouth,
Woodbine, Sea Isle City, Estell Manor and Newfield.

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

Frequent cloud to ground lightning is also occurring with these
storms. Lightning can strike 10 miles away from a thunderstorm. Seek
a safe shelter inside a building or vehicle.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3939 7437 3930 7454 3930 7462 3933 7468
      3927 7459 3929 7455 3918 7467 3917 7468
      3918 7468 3921 7516 3925 7520 3956 7502
      3950 7440 3944 7439 3941 7440 3944 7435
      3948 7438 3949 7431
TIME...MOT...LOC 1924Z 215DEG 16KT 3927 7509 3923 7465

JRK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
426 PM EDT SAT AUG 11 2018

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

0142 PM     HAIL             KING OF PRUSSIA         40.09N  75.40W
08/11/2018  E0.75 INCH       MONTGOMERY         PA   SOCIAL MEDIA

            DIME SIZE HAIL IN KING OF PRUSSIA. TIME ESTIMATED FROM
            RADAR.

&&

EVENT NUMBER PHI1801241

STAARMANN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
430 PM EDT SAT AUG 11 2018

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

0420 PM     HEAVY RAIN       SPRINGTOWN              40.56N  75.29W
08/11/2018  M3.91 INCH       BUCKS              PA   CO-OP OBSERVER

            OBSERVED RAINFALL SINCE 7AM EDT. THIS IS IN ADDITION TO
            1.14 INCHES THAT FELL BEFORE 7AM EDT.

&&

EVENT NUMBER PHI1801242

STAARMANN

Special Weather Statement
National Weather Service Mount Holly NJ
447 PM EDT SAT AUG 11 2018

PAZ060-070-101>103-112115-
Western Montgomery-Delaware-Western Chester-Eastern Chester-Berks-
447 PM EDT SAT AUG 11 2018

...STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN BERKS...
NORTHWESTERN MONTGOMERY...NORTHEASTERN CHESTER AND WEST CENTRAL
DELAWARE COUNTIES...

At 446 PM EDT, radar indicated strong thunderstorms were located
along a line extending from Fleetwood to near Glenmoore. Movement was
southeast at 15 mph.

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

Locations impacted include...
West Chester, Pottstown, Phoenixville, Coatesville, Westtown,
Downingtown, Birdsboro, Royersford, Fleetwood, East Greenville,
Elverson, Bally, Bechtelsville, Lyons, New Morgan, Cheyney, Pughtown,
Lionville-Marchwood, Glenmoore and Paoli.

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

Frequent cloud to ground lightning is also occurring with these
storms. Lightning can strike 10 miles away from a thunderstorm. Seek
a safe shelter inside a building or vehicle.

LAT...LON 4053 7587 4043 7551 3989 7548 4001 7586
      4017 7586 4017 7587
TIME...MOT...LOC 2046Z 302DEG 12KT 4045 7583 4005 7577

JRK