Special Weather Statement, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
1009 PM EDT Thu Jul 23 2020

.SYNOPSIS...
A weak cold front will slowly sink southward through the region
through Friday. The front will finally sink to our south by
Saturday as high pressure builds in from the north and remains
over us through Monday. A cold front will approach on Tuesday as
low pressure tracks through southern Canada. That front should
move through Tuesday night or Wednesday with another area of
high pressure building in towards the end of the week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
We have allowed the Severe Thunderstorm Watch to expire as the
bulk of the convective activity has weakened.

The cold front is making its way through central PA and into
northeast PA tonight. Another round of convection remains
possible as the front drops southward. While the instability
across the region appears to be waning, there is enough forcing
available to keep the convection going through the night. The
CAMs are also still hitting the area with more overnight storm
which could potentially be strong. The main focus appears to be
over the southern half of the CWA, as the northern portions
were worked over quite a bit during the afternoon and evening.

It will remain warm and humid overnight with lows only dropping
into the mid/upper 60s for the north areas and low/mid 70s for
Delmarva and srn NJ. Patchy fog may develop later tonight in
areas that receive rain the rest of today.

Made some minor adjustments to the temps, dews, sky, and wind
grids based on current observations and trends.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Friday... Some low clouds and light fog across the area during the
morning will mix out by mid-late morning with more showers and tstms
developing across the area for the afternoon. Once again, very warm
and humid with highs in the mid/upper 80s with dew points in the
upper 60s to low 70s. Pops are in the chc range for now, but a
higher chc is possible for some areas when it becomes clear which
boundaries remain after todays convection.

Friday night... Like today, scattered showers and tstms will be
across the area with the weak front pushing thru the area. Activity
will diminish overnight and patchy fog will develop overnight. Lows
in the upper 60s to low 70s region-wide.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Overview...

After an active stretch, a more benign pattern develops for the
weekend and into next week. Ridging over the center of the country
begins to shift east and gradually break down as a rather strong
trough, the most robust we've seen in awhile, digs into the Great
Lakes region. As the ridge folds over, a chunk of warmer air from
out to the west will be advected towards the region, and is likely
to lead to another uptick in the heat for the start of next week.
The main surface feature to watch next week will be a cold front
approaching from the west as low pressure tracks through southern
Canada ahead of the approaching trough. Timing of this front remains
uncertain (the overall trend is slower) but when it comes through it
will likely bring a round of showers and thunderstorms. A trend
towards high pressure and drier weather is then favored for late
week.

For sensible weather concerns this period, overall it looks like a
fairly low impact stretch. Sunday through Tuesday will be quite hot
and fairly humid. While each day will be marginal in terms of
needing any heat advisories, the combined effects of these three
days, continued warm overnights, and the recent lengthy stretch of
similarly hot and humid conditions with no breaks may lead to some
problems. Other than that, will monitor for any severe weather or
hydro concerns with the frontal passage, but it does not look too
alarming at the moment with shear on the weak side and the magnitude
of frontal forcing in question.

Dailies...

Saturday-Saturday night... Raised PoPs a bit on Saturday (mostly
slgt chc, some low end chc) especially to the south. This has seemed
possible for awhile, and while Saturday by no means looks like a day
with widespread showers and storms, does look like some isolated to
widely scattered convection is possible. This is mainly driven by a
continued warm and humid air mass and the continued nearby presence
of the weak and diffuse surface front from earlier in the week.
Additional surface boundaries such as the sea breeze may aid in
producing isolated convection. Still a mainly dry day overall as
high pressure will be starting to build in from the north. Warm and
humid again Saturday with highs near 90 as the "cold front" to the
south is very weak and will be mostly washed out by then.

Sunday-Sunday night... Rain chances drop further on Sunday with
weakening high pressure to the north moving a little further south.
Still a warm and fairly humid air mass in place, but little forcing
for ascent so while I can't totally rule out a shower especially
over Delmarva or southern NJ, should be a mainly dry day and another
warm night. Heat index values during the day Sunday rise towards 95
to 100, so approaching advisory criteria but more likely to stay
below.

Monday-Monday night... The trend is slower with the approach of a
cold front next week as weak high pressure looks to remain our
primary influence on Monday. Cut PoPs back to below mentionable
levels on Monday. Monday will be quite hot ahead of the front, with
highs getting into the low to mid 90s. Humidity, while not
oppressive, will remain elevated, and heat index values may approach
advisory criteria in some areas. Another warm and humid night.

Tuesday-Wednesday... Likely to be the most active part of the period
as low pressure tracks towards the southern Hudson Bay and into
Quebec by midweek. A cold front will approach from the west as it
does so and as a large trough digs into the Great Lakes. Ahead of
the front, PWAT values will rise and humidity will probably peak on
Tuesday, another very warm day. A band of showers and thunderstorms
will likely move through ahead of the front, but the timing remains
somewhat uncertain. Current trends favor the best rain chances being
late Tuesday into Tuesday night. May dry out by Wednesday, but given
what's happened with the last couple of cold fronts, would not be
too surprised if this one also slows down enough to keep warmer and
more humid air and even a storm risk still around on Wednesday,
especially to the south. Am not currently too concerned with severe
or hydro issues from this system. Wind fields look pretty weak and
always worry about a lack of forcing with low centers tracking this
far north. Just something to keep an eye on.

Later next week... Once the midweek front passes, assuming it
doesn't stall or wash out, then we should trend towards drier
weather towards the end of next week. With the more robust troughing
digging in to our west, we may finally see a somewhat more
substantial drop in temperatures or at least humidity towards the
end of next week, but still some uncertainty on that.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Overnight...Mainly VFR conditions with isolated to scattered
showers and thunderstorms overnight. Better chances to the south
and east of KPHL. Areas of fog are possible in places where rain
fell and skies have a chance to clear. Winds will generally be
southwest to west less than 10 knots but locally higher in and
near tstms. Moderate confidence with low confidence on timing of
any showers/convection.

Friday...MVFR cigs/vis are possible through mid morning as
winds will remain light across the region. Winds will generally
be less than 10 knots but enough mixing is expected to bring
conditions up to VFR through the afternoon and evening.
Scattered showers and tstms will again develop with more
restrictions possible.

Outlook...

Fri night...Showers and scattered tstms ending and localized fog
developing.

Saturday-Saturday night... Mainly VFR during the day Saturday.
Slight chance of afternoon showers or thunderstorms mainly near and
south of PHL. Overnight, fog development is possible, with some
areas of IFR or lower possible. Winds light and variable. High
confidence overall except low confidence in how widespread fog will
be overnight.

Sunday-Sunday night... Mainly VFR. Patchy fog possible Sunday
morning. Southwest wind 5 to 10 kt. Moderate to high confidence.

Monday-Monday night... Mainly VFR. Southwest wind 5 to 10 kt.
Moderate to high confidence.

Tuesday-Wednesday... Prevailing VFR, but a band of showers and
thunderstorms will likely move through the region ahead of a cold
front with a period of restrictions. Winds mainly west-southwest at
5 to 10 kt, becoming more west or west-northwest on Wednesday. Low
confidence.

&&

.MARINE...
A summerlike pattern continuing with sub-SCA conditions exected
along with late afternoon/evening scattered showers and tstms later
today and Friday. Winds will be mostly west to southwest at around
10 knots much of the time. Locally winds winds and seas near
tstms.

Outlook...

Through Tuesday night... No marine headlines are anticipated. Mainly
dry weather expected over the waters with only isolated tstms
possible Saturday. Light southeast winds on Saturday then mainly SW
at 10 to 15 kt for the remainder of the period. Seas 2 to 4 ft.

Fri night...sub-SCA expected. Scattered evening showers and
tstms mostly for the DE and srn NJ waters.

Rip Currents...

With light winds and seas continuing, the risk for the formation of
dangerous rip currents is expected to remain low through Friday.

&&

.EQUIPMENT...
The NOAA Weather Radio All-Hazards broadcast from Hibernia Park,
Pennsylvania (Station WNG-704) will remain off the air until
further notice due to damage suffered in the June 3 derecho.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

Synopsis...O'Brien
Near Term...Meola/O'Hara
Short Term...O'Hara
Long Term...O'Brien
Aviation...Meola/O'Brien/O'Hara
Marine...O'Brien/O'Hara
Equipment...WFO PHI

Hazardous Weather Outlook
National Weather Service Mount Holly NJ
1116 PM EDT Thu Jul 23 2020

DEZ001>003-MDZ008-012-015-019-020-NJZ001-007>010-012-013-015>023-027-
PAZ054-055-060>062-070-071-101>106-250330-
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-
1116 PM EDT Thu Jul 23 2020

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...Tonight.

Scattered thunderstorms will bring locally heavy rainfall. Flooding
of roads, areas of poor drainage, and small streams and creeks is
possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.

DEZ004-NJZ014-024>026-250330-
Delaware Beaches-Eastern Monmouth-Atlantic Coastal Cape May-
Coastal Atlantic-Coastal Ocean-
1116 PM EDT Thu Jul 23 2020

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

.DAY ONE...Tonight.

Scattered thunderstorms will bring locally heavy rainfall. Flooding
of roads and areas of poor drainage is possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.

ANZ430-431-450>455-250330-
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-
1116 PM EDT Thu Jul 23 2020

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

.DAY ONE...Tonight.

Thunderstorms may be accompanied by wind gusts in excess of 35
knots.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1139 PM EDT THU JUL 23 2020

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

1107 PM     TSTM WND DMG     3 WSW EARLEVILLE        39.40N 75.97W
07/23/2020                   CECIL              MD   UTILITY COMPANY

            DOWNED WIRES NEAR GROVE NECK ROAD IN
            EARLEVILLE. TIME ESTIMATED FROM RADAR.

&&

CMS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1201 AM EDT FRI JUL 24 2020

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

1145 PM     MARINE TSTM WIND 4 SSW ELSINBORO TWP     39.48N 75.54W
07/23/2020  M44 MPH          SALEM              NJ   MESONET

            NJWXNET GAUGE.

&&

CMS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1206 AM EDT FRI JUL 24 2020

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

1032 PM     TSTM WND DMG     MARSHALLTON             39.72N 75.65W
07/23/2020                   NEW CASTLE         DE   FIRE DEPT/RESCUE

            SEVERAL REPORTS OF POWER LINES DOWN IN THE
            STANTON AND MARSHALLTON AREAS. TIME
            ESTIMATED FROM RADAR.

&&

CMS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1211 AM EDT FRI JUL 24 2020

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

1200 AM     HEAVY RAIN       1 SW GLASGOW            39.59N 75.76W
07/24/2020  M2.42 INCH       NEW CASTLE         DE   TRAINED SPOTTER

            A STORM TOTAL OF 2.42 INCHES OF RAIN WAS
            MEASURED NEAR GLASGOW, WITH 2.28 INCHES
            RECORDED IN ONE HOUR (11P-12A).

&&

MEOLA

Special Weather Statement
National Weather Service Mount Holly NJ
1214 AM EDT Fri Jul 24 2020

NJZ010-012-013-015-240445-
Western Monmouth-Somerset-Middlesex-Mercer-
1214 AM EDT Fri Jul 24 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHEASTERN MERCER...
SOUTHEASTERN SOMERSET...NORTHEASTERN MONMOUTH AND MIDDLESEX
COUNTIES...

At 1214 AM EDT, radar indicated strong thunderstorms were located
along a line extending from Skillman to Morganville. Movement was
northeast at 15 mph.

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

Locations impacted include...
New Brunswick, Somerset, Middletown, Old Bridge, East Brunswick,
South Brunswick, Sayreville, North Brunswick, Princeton, Keansburg,
Matawan, Jamesburg, Hightstown, Cranbury, Hopewell, Rocky Hill,
Millstone, Skillman, Brownville and Yorketown.

This includes the following highways...
 New Jersey Turnpike between exits 9 and 10.
 Garden State Parkway between mile markers 114 and 127.

If outdoors, consider seeking shelter inside a building.

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

LAT...LON 4032 7424 4026 7446 4028 7454 4032 7455
      4038 7482 4054 7456 4051 7426 4050 7426
      4050 7428 4046 7426 4044 7420 4046 7418
      4045 7413 4042 7405
TIME...MOT...LOC 0414Z 236DEG 13KT 4039 7472 4036 7428

Staarmann

Special Weather Statement
National Weather Service Mount Holly NJ
1232 AM EDT Fri Jul 24 2020

NJZ009-015-PAZ070-101>106-240500-
Hunterdon-Mercer-Lower Bucks-Upper Bucks-Eastern Montgomery-Western
Montgomery-Delaware-Western Chester-Eastern Chester-
1232 AM EDT Fri Jul 24 2020

...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT SOUTH CENTRAL
HUNTERDON...WEST CENTRAL MERCER...MONTGOMERY...CENTRAL BUCKS...
NORTHEASTERN CHESTER AND NORTH CENTRAL DELAWARE COUNTIES...

At 1231 AM EDT, strong thunderstorms were clustered over Lansdale, or
19 miles northwest of Philadelphia, moving northeast at 55 mph.

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

Locations impacted include...
Norristown, Phoenixville, Lansdale, West Norriton, East Norriton,
Perkasie, Doylestown, Byram, Conshohocken, Hatboro, Souderton,
Bedminster, Ambler, Collegeville, Royersford, Chalfont, Tinicum,
Trappe, Hatfield and New Hope.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 316 and 339.
 Northeast Extension between mile markers 21 and 37.
 Interstate 76 in Pennsylvania between mile markers 327 and 333.
 Interstate 476 in Pennsylvania between mile markers 13 and 19.

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 3996 7548 4015 7571 4054 7509 4033 7484
TIME...MOT...LOC 0431Z 227DEG 49KT 4025 7531

Davis