Areal Flood Advisory 93, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
636 PM EDT Wed Jun 19 2019

.SYNOPSIS...
A stalled front will remain across our area through tonight, then
begin to lift north during Thursday as an area of low pressure moves
toward the area. This low tracks just to our north late Thursday
afternoon and Thursday evening, with its cold front crossing our
region Thursday night. A secondary front arrives early Friday
morning, then high pressure arrives for Saturday night before
shifting offshore Sunday. A warm front lifts across the area Sunday
night into Monday. High pressure builds to our south through the
middle of next week, while a surface trough develops across the East
Coast.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A nearly stationary front being enhanced by some ongoing
convection will remain in place across the central part of the
region through tonight. This is helping to focus some convection
this evening, some of which is producing locally very heavy
rain in a short period of time. As a result, the Flash Flood
Watch remains in effect for a good portion of the area. Warm
rain processes and a more low-topped nature of the convection is
limiting the lightning, however some updrafts have pulsed up
some to result in a stronger core aloft for a time and therefore
more lightning. Even some backbuilding noted into Philadelphia
County from convection in Burlington County. Overall, the
thunder coverage looks more isolated. For the 630 PM update,
adjusted the PoPs to place the highest values closer to the
boundary where ongoing convection is occurring. Much of the
guidance indicates an uptick in showers and perhaps isolated
thunder late this evening into the wee hours of Thursday morning
near the I-95 corridor. Temperatures are a challenge due to the
stalled front and ongoing heavy downpours/low clouds, however
these were adjusted using the current observations then the LAMP
guidance was blended in. Some low clouds have arrived along
parts of the New Jersey coast, and low clouds are expected to
spread across much of the area through the overnight within this
moisture laden airmass.

Otherwise, with high precipitable water across the area, we
will continue to see heavy rainfall. With such wet antecedent
conditions after the rain from the past couple of days, we
remain sensitive to flash flooding. While the showers are
moving, they aren't moving that quickly which will allow for
heavy rain to fall over a single location for a longer period
time increasing the risk for flash flooding.

We should lose the thunder as we head into the overnight period
as the atmosphere starts to stabilize but showers will remain
possible. Not much relief overnight as we remain socked in with
clouds and temperatures will have a hard time dropping off too
much. Lows are expected to remain in the 60s to lower 70s. With
so much moisture across the region (and dew points into the
upper 60s to lower 70s), expect fog and low clouds to develop
once again and continue into the morning.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
For the 630 PM update, made some adjustments to the PoPs with
the increase delayed some eastward. Also added in a mention of
heavy rain and gusty winds for the afternoon given the potential
for strong to severe thunderstorms.

Another day, more convection. Seems to be the theme of the week
around the Mid-Atlantic but thankfully this looks to be the
last day of unsettled weather as we head towards the end of the
week.

A low pressure system will track through the Ohio Valley and
into the mid-Atlantic along the stalled boundary. Good surface
heating is expected to take place on Thursday and will help with
convective initiation as the majority of the forecast area
looks to remain in the warm sector. SPC has placed the majority
of our forecast area into a slight risk for severe weather.
There is decent shear (improved in the lower levels than is
present Wednesday) and CAPE >1000 J/kg present and convection
should have no problem developing ahead of the approaching cold
front, although there may be more forward storm motion present
than there is Wednesday. Damaging winds looks to be the main
threat at this time but there is some indication we could see
supercells develop in which case we can't rule out the
possibility of rotating cells. May need to watch the track of
the weak surface low as the surface winds back back to the
southeast ahead of it resulting in enhanced low- level shear.
With PWATs remaining around 2 inches, we will continue to have a
heavy rain threat and though the coverage may not be as
widespread, several areas have had a fair amount of rain this
week. Another Flash Flood Watch may be needed for the day
Thursday, although given storm motions should be faster and some
uncertainty where the heaviest rain will fall we held off for
now.

Temperatures will rise into the 80s through much of the area
and even into the lower 90s across southern Delaware and nearby
areas of eastern Maryland. The limiting factor, especially
across our northern areas, will be the cloud cover as the day
starts off with fog/low clouds across the region and just how
fast they clear will play a role in just how fast temperatures
can rise through the day.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
An area of low pressure will continue to move to our north and
strengthen as it does so. This will drag a cold front across the
area during the evening and overnight hours Thursday, with a
secondary front or surface trough moving across the area Friday
morning. This will keep enhanced precipitation chances through
Thursday night and Friday morning as several short
wave/vorticity impulses will move across the area and combine
with some enhance moisture. There remains instability Thursday
night and Friday morning, so thunderstorms will remain in the
forecast, and with PW values around 1.5 inches, heavy rainfall
could continue to be a threat.

The fronts will continue to push to our south during the day
Friday, and showers will come to an end by midday. However, the
pressure gradient will tighten with low pressure to our
northeast and high pressure to our northwest. This will likely
lead to be quite gusty during the day Friday, possibly reaching
20-30 mph.

High pressure remains to our west for Friday night into
Saturday, briefly building over the area Saturday night. This
will keep dry conditions across the area through Friday night
and Saturday. Winds will likely gust again Saturday, but not as
gusty as Friday, generally 15-20 mph.

The high then shifts offshore Sunday, before a warm front
begins to approach Sunday night. Most of the day Sunday is
expected to be dry, however, this could begin to change by late
Sunday into Sunday night as some moisture and a couple of short
waves move across the area and may lead to a chance of showers
and thunderstorms.

High pressure builds into the Northeast Monday as the upper
level trough lifts out of the region into the Canadian
Maritimes. A surface low will move just north of the Great
Lakes, drawing a warm front northward across the mid-Atlantic
during the day. Thus, warmer highs than Sunday can be expected.
Precipitation looks rather limited at this point with the front,
but kept a chance for showers and thunderstorms in the grids
for now. A return to a more humid airmass will occur, though, as
PWATs jump back to near 2 inches across the region.

The surface low continues to deepen as it moves into central
Ontario and eastern Quebec Monday night into Tuesday. As it does
so, a cold front will be pulled out of the Ohio Valley toward
the mid-Atlantic. At this point, model consensus appears to
shunt the precipitation north of the area. Best chances for
showers and thunderstorms looks to be across the northwestern
portions of the CWA at this time. There will be some
instability, so there is the potential for thunderstorms, but
timing will help determine any potential severe risk. If the
front is slower to arrive, coming Tuesday afternoon, the threat
may be greater. Regardless, it looks to be a warm a humid day
with highs in the upper 80s to near 90.

Highs will be a little cooler Wednesday behind the front, with
most places topping out in the mid 80s. Some discrepancy remains
as to how quickly the trough exits the Northeast, thus,
continued a slight chance for showers through the day Wednesday.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...Some showers and isolated thunderstorms through this
evening, then perhaps some more late tonight and toward daybreak.
Much of this should be near ILG to PHL to the north. ceilings
varying from VFR to MVFR or locally IFR are expected to all lower to
IFR overnight. Visibility restrictions with local downpours, then
perhaps some fog overnight. Winds east or southeast 5 knots or less,
to locally light and variable. Low confidence on the on the timing
of widespread IFR ceilings.

Thursday...IFR ceilings improve to MVFR during the morning, then
possibly becoming VFR at PHL and ILG by early afternoon. Some
showers early especially near ILG, PHL, PNE to TTN, then more
widespread showers and some thunderstorms from west to east during
the afternoon. Times of IFR/LIFR especially visibilities with the
downpours. Variable winds, becoming south to southwest 10 knots or
less. Locally higher wind gusts possible with stronger afternoon
thunderstorms.

OUTLOOK...
Thursday night... VFR possible early, lowering to MVFR
overnight. Especially with any showers and thunderstorms.

Friday...MVFR conditions possible early, before improving to
VFR during the day. Chance of showers early. Winds shift to
northwest with gusts 20-25 knots.

Friday night-Saturday night...VFR conditions expected. Northwest
winds may gust 15-20 knots during the day Saturday.

Sunday-Sunday night...MVFR conditions expected. Chance of
showers Sunday night. West to southwest winds may gust around 15
knots during the day Sunday.

Monday...VFR with southwest winds 5 to 10 knots. Gusts to 15
knots possible, especially along the shore.

&&

.MARINE...
Sub-Small Craft Advisory conditions are expected to continue
through Thursday. Winds out of the south to southeast around 10
to 15 knots tonight, becoming southwest on Thursday. Seas around
1 to 3 feet.

Higher winds and waves in showers and thunderstorms.

Outlook...
Thursday night-Friday night...Small Craft Advisory conditions
possible with guts 25-30 knots possible. Gale force winds
possible during the day Friday.

Saturday-Sunday night...Conditions expected to drop below
advisory levels by Saturday and remain below advisory levels
through Sunday night.

Monday...sub SCA conditions expected with southwesterly winds
10 to 15 knots and seas 1 to 3 feet.

Rip Currents...

A low risk for the development of dangerous rip currents is
expected to continue through today with waves in the surf zone 3
feet or less.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flash Flood Watch until 6 AM EDT Thursday for PAZ054-055-
     060>062-070-071-101>106.
NJ...Flash Flood Watch until 6 AM EDT Thursday for NJZ001-007>010-
     012>019.
DE...Flash Flood Watch until 6 AM EDT Thursday for DEZ001.
MD...None.
MARINE...Small Craft Advisory from 8 PM Thursday to 6 PM EDT Friday for
     ANZ430-431-451>455.
     Small Craft Advisory from 8 AM to 6 PM EDT Friday for ANZ450.

&&

Synopsis...Gorse/Robertson
Near Term...Gorse/Meola
Short Term...Gorse/Meola
Long Term...Davis/Robertson
Aviation...Davis/Gorse/Robertson/Meola
Marine...Davis/Robertson/Meola

Hazardous Weather Outlook
National Weather Service Mount Holly NJ
356 PM EDT Wed Jun 19 2019

DEZ001-NJZ001-007>010-012-013-015>019-PAZ054-055-060>062-070-071-
101>106-202000-
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-
Western Monmouth-Mercer-Salem-Gloucester-Camden-
Northwestern Burlington-Carbon-Monroe-Berks-Lehigh-Northampton-
Delaware-Philadelphia-Western Chester-Eastern Chester-
Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
356 PM EDT Wed Jun 19 2019

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

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

.DAY ONE...This afternoon and tonight.

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

   Flash Flood Watch.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Strong to severe thunderstorms are possible Thursday afternoon and
evening.

.SPOTTER INFORMATION STATEMENT...

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

DEZ002-003-MDZ008-012-015-019-020-NJZ020>023-027-202000-
Kent-Inland Sussex-Cecil-Kent MD-Queen Annes-Talbot-Caroline-Ocean-
Cumberland-Atlantic-Cape May-Southeastern Burlington-
356 PM EDT Wed Jun 19 2019

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

.DAY ONE...This afternoon and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Strong to severe thunderstorms are possible Thursday afternoon and
evening.

.SPOTTER INFORMATION STATEMENT...

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

NJZ014-202000-
Eastern Monmouth-
356 PM EDT Wed Jun 19 2019

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

This Hazardous Weather Outlook is for central 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.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Strong to severe thunderstorms are possible Thursday afternoon and
evening.

.SPOTTER INFORMATION STATEMENT...

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

DEZ004-NJZ025-026-202000-
Delaware Beaches-Coastal Atlantic-Coastal Ocean-
356 PM EDT Wed Jun 19 2019

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

.DAY ONE...This afternoon and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Strong to severe thunderstorms are possible Thursday afternoon and
evening.

.SPOTTER INFORMATION STATEMENT...

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

ANZ430-431-450>455-NJZ024-202000-
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-
Atlantic Coastal Cape May-
356 PM EDT Wed Jun 19 2019

This Hazardous Weather Outlook is for Atlantic coastal waters,
Delaware Bay Waters and southern New Jersey.

.DAY ONE...This afternoon and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Some thunderstorms Thursday afternoon and evening may produce local
wind gusts to 34 knots or greater.

There is a chance for occassional gale force winds Friday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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