Special Weather Statement, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
624 AM EDT Mon Sep 2 2019

.SYNOPSIS...
A cold front will approach late today and move through tonight. High
pressure will briefly become established on Tuesday. By Wednesday,
another cold front will approach the area and will move through
Wednesday night. Hurricane Dorian may approach the mid-Atlantic for
Thursday and Friday before it moves out to sea. Another cold frontal
passage is possible next weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Warm front over western Pennsylvania continues tracking east,
and a line of showers and thunderstorms developed out ahead of
it. This line is currently moving through eastern Pennsylvania,
and is a bit farther south than it appeared was tracking
earlier. Will up PoPs for thee Delaware valley, as the line is
approaching berks county. Locally heavy rain and lightning are
possible during that time.

A warm and humid airmass overspreads the region today, although
temperatures may become somewhat tempered by cloud cover. There
should be enough breaks in the clouds today to result in highs
generally in the lower 80s for most of the Lehigh Valley,
northern, and coastal New Jersey, and in the mid 80s for Philly,
southern New Jersey, and Delmarva. Surface dewpoints will be
well in the 60s, possibly approaching 70 in some spots.

Cold front approaches late this afternoon, and another round of
showers and thunderstorms will develop out ahead of it. With strong
shortwave energy passing through the far northern zones, will focus
categorical PoPs on the southern Poconos and far northern New
Jersey, and likely PoPs south through I-95 or so.

SPC has a Marginal risk for severe weather for most of the region.
SB CAPE values will be around 1500 J/kg, possibly as high as 2000
J/kg, and 0-6 km Bulk Shear will be on the order of 35-40 kt.
Multicells and a few supercells are possible with potentially
damaging winds and heavy rain.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
Cold front works its way through the region Monday night. Showers
and thunderstorms continue through the evening, but will taper off
through the evening with loss of diurnal heating. Most of the
showers and thunderstorms should be done just after midnight or so.

Although cold front will be through the region, winds will be light
behind the front. Since it will take time for the low level moisture
to dry out, there should be some patchy fog and stratus developing
in the late night/pre-dawn hours.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Tuesday through Thursday...

For Tuesday, weak high pressure builds in just off the coast while a
frontal boundary dissipates to our south. This will result in warm
but less humid conditions compared to Monday with mainly sunny
skies. Highs will be mainly in the low to mid 80s except a bit
cooler over the southern Poconos as well as along the coast due to
onshore breezes.

Tuesday night into Wednesday, the high weakens to our east as low
pressure moves from northern Ontario into Quebec. This will result
in another surge of very warm, moist air arriving for Wednesday
before the system's cold front arrives from the north and west late
day. The combination of the cold front and diurnal heating of the
moist airmass will trigger another round of showers and
thunderstorms by Wednesday afternoon into the evening. These look to
start out over northern zones in the afternoon before potentially
reaching the I-95 corridor and points S/E by the evening.
Indications at this point are that ML CAPE values may reach 500-
1000+ J/kg along with deep layer shear of 30-40+ knots. This may
result in some storms becoming organized and severe...especially
north of the I-95 corridor where the shear looks to be the
strongest. One limiting factor will be that the best upper level
dynamics look to be just to our north. Highs Wednesday will be
well into the 80s to around 90 for the urban corridor with temps
a bit cooler once again along the coast and for the southern
Poconos.

The cold front moves through Wednesday evening before stalling near
the southern Delmarva by early Thursday. Expect storms to diminish
by later Wednesday evening to just a few showers. Also by early
Thursday, high pressure will be building in to our north over the
Great Lakes while Hurricane Doria will be near the Carolina coast.
This will result in a moist, NE flow over the mid Atlantic which
will persist through the day as Doria slowly moves northeast near
the Carolina coast. This will keep conditions mainly cloudy
with periods of light rain, showers, and drizzle as some of the
moisture from the outer edges of Doria interacts with the
stalled front over the region. Temperatures will be much cooler
compared to Wednesday with highs mainly in the 70s except some
upper 60s over the Poconos.

Thursday night through Sunday...

The main focus for this period will be on Dorian and its potential
impacts for our region as the storm moves north. The timeframe
of greatest concern is Thursday night through Friday. At this
point though it is still too early to say with confidence what
the impacts will be for our region. In the big picture, forecast
models continue to depict the overall idea of the storm
tracking from the Carolinas late Thursday northeastward off the
east coast through Friday into Saturday as Dorian is picked up
by an upper level trough moving from the lower Great Lakes into
the northeast. This would take it near or east of our coastal
waters. During this time it will also be undergoing gradual
transition to post-tropical as it interacts with a frontal
boundary as well as the upper level trough and will be in a much
weaker state compared to what it currently is. The main
uncertainties are the exact track and speed of the system which
will determine just how close it gets to the coast and what the
resulting impacts will be for our area in terms of wind and
rain. The GFS continues to suggest the storm will get just close
enough to bring the western shield of heavy rain and strong
winds into southern DE and NJ while the ECMWF and the GEM Global
track the system about 50-100 miles farther south and east as
it moves off the coast. In terms of the gridded forecast, both
POPs and winds were raised slightly from previous forecast but
otherwise no big changes. Forecast has the chance of rain in for
most of the CWA for Friday along with NE winds 20-30 gusting 30
to 40 mph along the coast.

Later next weekend... Most indications are that Dorian will be long
gone by Saturday afternoon. A cold frontal passage is likely late
Saturday or Saturday night. This front looks to come through with
little fanfare given rather cool and dry air ahead of it as Dorian
pulls away. Kept PoPs below mentionable levels for now but may have
to add at least a slight chance in future updates. High pressure
looks to build in by Sunday with quiet and seasonable weather
returning.

&&

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

Today...MVFR/IFR CIGs this morning, and morning SHRA/TSRA with
brief sub-VFR conditions. Conditions improve to VFR by late
morning or early afternoon. Cold front approaches late with
SHRA/TSRA developing by 20Z, first at KRDG/KABE, then at
KTTN/KPNE/KPHL/KILG. Lower confidence on SHRA/TSRA at KMIV/KACY.
South winds less than 10 kt.

Tonight...SHRA/TSRA through this evening with sub-VFR conditions.
Patchy fog develops late with sub-VFR conditions. LGT/VRB winds.

Outlook...

Tuesday-Tuesday night... Patchy fog possible early Tuesday.
Otherwise, VFR. Winds light and variable on Tuesday, becoming
light southeasterly in the evening then light southerly
overnight.

Wednesday-Wednesday night... Mainly VFR but with showers and
thunderstorms possible in the afternoon and evening which could
bring brief restrictions. Southwest winds around 10 kt gusting
up to 20 kt on Wednesday, switching to northwesterly then
northerly overnight and decreasing.

Thursday... Currently expecting mainly VFR with northeasterly winds,
but gusty winds and sub-VFR conditions may be possible especially
late in the day at MIV and ACY depending on the track of Hurricane
Dorian.

&&

.MARINE...
Today through tonight...Sub-SCA conditions. Southeast winds 10-15 kt
with gusts up to 20 kt, becoming south later this morning, then west
late tonight. Seas 2 to 4 feet. Showers and thunderstorms with gusty
winds possible this morning, and then again late this afternoon and
tonight.

Outlook...

Quiet boating weather is expected Tuesday with light winds and
seas 2 to 4 ft. On Wednesday, southwesterly winds may gust near
to above 20 kt, though conditions should remain just below SCA
criteria with decreasing winds Wednesday night and seas running
3 to 4 ft.

Building seas are likely later this week as Hurricane Dorian moves
up the East Coast. Even if the center passes well to our east,
confidence is growing for an extended period of potentially
dangerous seas and strong winds by late Thursday through
Friday. Mariners in the area should closely monitor the progress
of Dorian.

Rip Currents...

The long period swell will persist through today, and with
southeast winds turning south, there is a high risk for the
formation of dangerous rip currents through at least this
evening.

Another round of waves and swell associated with Hurricane Dorian
are expected to approach the area Wednesday or later, which could
lead to another period of moderate or high risk of rip currents.

&&

.TIDES/COASTAL FLOODING...
The high tides remain elevated with the current new moon phase.
While astronomical tides will gradually begin to recede in the
coming days, light onshore winds today will also help keep water
levels elevated. As a result, spotty minor tidal flooding
remains possible today, especially with the astronomically
higher evening/nighttime high tides. However, most indications
are that any flooding should remain below thresholds needed to
trigger an advisory.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...High Rip Current Risk through this evening for NJZ014-024>026.
DE...High Rip Current Risk through this evening for DEZ004.
MD...None.
MARINE...None.

&&

Synopsis...Fitzsimmons
Near Term...MPS
Short Term...MPS
Long Term...Fitzsimmons
Aviation...Fitzsimmons/MPS
Marine...Fitzsimmons/MPS
Tides/Coastal Flooding...

Hazardous Weather Outlook
National Weather Service Mount Holly NJ
357 AM EDT Mon Sep 2 2019

DEZ001>003-MDZ008-012-015-019-020-NJZ001-007>010-012-013-015>023-027-
PAZ054-055-060>062-070-071-101>106-030800-
New Castle-Kent-Inland Sussex-Cecil-Kent MD-Queen Annes-Talbot-
Caroline-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-
Western Monmouth-Mercer-Salem-Gloucester-Camden-
Northwestern Burlington-Ocean-Cumberland-Atlantic-Cape May-
Southeastern Burlington-Carbon-Monroe-Berks-Lehigh-Northampton-
Delaware-Philadelphia-Western Chester-Eastern Chester-
Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
357 AM EDT Mon Sep 2 2019

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

.DAY ONE...Today and tonight.

Showers and thunderstorms are possible this afternoon and evening. A
few storms may be strong to severe with a primary threat of strong
winds.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

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.

DEZ004-NJZ014-024>026-030800-
Delaware Beaches-Eastern Monmouth-Atlantic Coastal Cape May-
Coastal Atlantic-Coastal Ocean-
357 AM EDT Mon Sep 2 2019

...HIGH RIP CURRENT RISK IN EFFECT THROUGH THIS EVENING...

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

   High Rip Current Risk.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Hurricane Dorian should pass to the south and east later this week.
However, it may impact coastal areas with rough surf, dangerous rip
currents, and strong winds late this week. Please monitor forecasts
for the latest information on Dorian.

.SPOTTER INFORMATION STATEMENT...

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

ANZ430-431-450>455-030800-
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-
357 AM EDT Mon Sep 2 2019

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

.DAY ONE...Today and tonight.

There is a low probability for widespread hazardous weather.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Hurricane Dorian should track south and east of the coastal waters
late this week. However, it may impact the coastal waters with
increased swells, high waves, and strong winds late Thursday through
Friday. Please monitor forecasts for the latest information on
Dorian.

.SPOTTER INFORMATION STATEMENT...

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

Special Weather Statement
National Weather Service Mount Holly NJ
807 AM EDT Mon Sep 2 2019

PAZ060-101>103-021245-
Western Montgomery-Western Chester-Eastern Chester-Berks-
807 AM EDT Mon Sep 2 2019

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN BERKS...
WEST CENTRAL MONTGOMERY AND NORTHERN CHESTER COUNTIES...

At 802 AM EDT, radar indicated strong thunderstorms were located
along a line extending from Adamstown to near Terre Hill to near
Bareville. Movement was east at 25 mph.

Wind gusts up to 40 mph are possible with these storms.

Locations impacted include...
Pottstown, Phoenixville, Coatesville, Downingtown, Birdsboro,
Royersford, Parkesburg, Honey Brook, Elverson, New Morgan, Pughtown,
Marshallton, Lionville-Marchwood, Glenmoore, Chester Springs,
Lionville, Cedarville, Stowe, Shillington and Spring City.

LAT...LON 4031 7561 4012 7548 3989 7571 3997 7598
      4004 7593 4011 7594 4014 7588 4029 7611
TIME...MOT...LOC 1202Z 279DEG 21KT 4025 7605 4019 7600 4007 7612

Staarmann

Special Weather Statement
National Weather Service Mount Holly NJ
845 AM EDT Mon Sep 2 2019

PAZ060-070-101>104-021330-
Eastern Montgomery-Western Montgomery-Delaware-Western
Chester-Eastern Chester-Berks-
845 AM EDT Mon Sep 2 2019

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN BERKS...CENTRAL
MONTGOMERY...NORTHEASTERN CHESTER AND NORTHEASTERN DELAWARE
COUNTIES...

At 845 AM EDT, a strong thunderstorm was located over Glenmoore, or
15 miles northwest of West Chester, moving east at 25 mph.

Wind gusts up to 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Norristown, Pottstown, Phoenixville, West Norriton, East Norriton,
Downingtown, Conshohocken, Collegeville, Royersford, Trappe, Honey
Brook, Schwenksville, Elverson, New Morgan, Pughtown, Bryn Mawr,
Trout Lake, Radnor Township, Lionville-Marchwood and Valley Forge.

If outdoors, consider seeking shelter inside a building.

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

LAT...LON 4014 7588 4017 7593 4019 7592 4030 7533
      3998 7530 4003 7588 4004 7593 4008 7593
      4011 7594
TIME...MOT...LOC 1245Z 264DEG 21KT 4013 7579

Staarmann