Special Marine Warning 112, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
334 PM EDT Wed Aug 12 2020

.SYNOPSIS...
A cold front will remain stalled over our area through at least
Friday. Several areas of low pressure will develop and track
along this front through the weekend, while high pressure will
build to our north. The boundary may return to our area Sunday
into early next week as a low moves through Canada while a
second low forms along the boundary to our south.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
It's been a busy afternoon across the area, though evolving largely
as expected with numerous thunderstorms mainly along and southeast
of the urban corridor. Reminiscent of the July 6 thunderstorms event
with elliptical outflow propagating away from the initial dominant
storm complex of the day. That outflow has then been initiating new
cells. Lack of shear has kept this event from being a full on repeat
of July 6, but nonetheless a number of reports of flash flooding and
wind damage have come in. It does appear that the boundary made it
far enough southeast to keep the storms away from areas such as the
Lehigh Valley and most of central and northern NJ. Have trimmed back
the Flash Flood Watch to account for this.

Given the lack of shear and lack of much synoptic lift, do not
expect widespread storm activity to carry on for very long this
evening. Most storms should dissipate by around sunset or soon
after. In the meantime, however, locally heavy rain and a couple of
stronger storms with gusty winds remain likely with the remaining
storms.

For tonight, expecting mainly rain-free conditions. Some shortwave
energy will begin approaching from the southwest later in the night,
so some showers or an isolated thunderstorm will be possible
especially heading towards daybreak. And with so much moisture,
can't rule out general pop up showers just about anywhere. The
atmosphere will likely be pretty worked over from the day's
convection, however. Will also once again be watching for patchy fog
and low stratus development. Despite potential for higher level
cloudiness, the plentiful low level moisture and nearly calm winds
should favor another round of this tonight, and have added that
mention into the grids. Otherwise, warm and muggy once again with
lows mainly in the low 70s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
A similar story synoptically on Thursday as on Wednesday as a
stalled frontal boundary remains over the area, making little if any
southeastward progress. Another unsettled day is likely. Several
questions with regard to the extent of convection, however. Cloud
cover is likely to be much greater on Thursday compared to Wednesday
morning, and will keep highs mainly in the low to mid 80s. Morning
fog and low clouds may also take an extra hour or two to lift versus
prior days. So instability will be considerably lower. In addition,
the atmosphere may remain somewhat worked over from the prior day's
activity. So these are negatives for convection. However, we also
have a fairly robust, convectively enhanced shortwave approaching
from the southwest on Thursday. Lift is likely to be better than on
Wednesday, and the approaching shortwave will help increase deep
layer shear up from near zero to around 20 to 25 kt along and south
of the front. The one thing not in question is moisture, which if
anything will be greater than on Wednesday with PWATs mainly above 2
inches across the area.

So putting it all together, another day where at least scattered
showers and thunderstorms are likely. While possible over most of
the region, they should mainly favor the areas that saw the greatest
coverage on Wednesday. Despite the improved lift and shear, the
weaker instability will likely be a major hindrance to severe
weather, and expect that threat to be less than on Wednesday. Storm
coverage in general should be at least somewhat lower as well.
However, with the rich moisture and deep warm cloud layers, heavy
rain will once again be a concern. This will be especially true if
the same areas receiving recent heavy rains get hit yet again. Not
confident enough in storm coverage at this point to extend the Flash
Flood Watch, but this will need to be reevaluated.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Synoptic Overview...

The start of the extended will feature a a pair of H5 ridges
centered over the SW and SE US, while to the north of these features
a succession of shortwave ridges and troughs will be passing through
the Central/Northern US and Southern Canada. For our area the most
impactful shortwave is currently centered near Arkansas/Missouri.
This wave will only very slowly progress eastward over the next few
days, while a fairly amplified (but  progressive) ridge develops to
its north. Although the wave itself may not reach our area until
Sunday/early next week numerous vort maxes will eject out ahead of
it into our area (the most potent likely impacting us on Thursday).
A more amplified trough will push the Canadian ridge eastward Sunday
into Monday, and this trough should ultimately absorb the
aforementioned southern shortwave. By early next week the overall
synoptic pattern over the US will then become characterized by an
amplified ridge over the western US and a longwave trough over the
eastern US, with various shortwaves pivoting SEwrd around the base
of the larger trough towards our area.

At the surface the cold front from today will only very slowly
progress southward with its thermal/moisture gradients washing
out somewhat over the first few days of the long term. Guidance
has become more bullish on developing a stronger frontal low
south of our area on Friday, and that low combined with the High
over eastern Canada will promote a somewhat drier E-NE flow
Friday into Saturday. By early next week another frontal low
will form to our south and begin to phase with a stronger low in
Canada. It is possible the boundary returns northward towards
our area in this time period and there could also be a cold
frontal passage associated with the northern low, but details
remain nebulous.

Dailies...

Friday/Saturday... The current suite of guidance paints a relatively
drier picture for this period as High Pressure builds to our north,
and the boundary is pushed south. This is a somewhat different
evolution than guidance had been depicting the past couple nights so
only partially cut PoPs with this package, but it is possible they
can be decreased further if guidance continues coming in with this
drier solution. Generally expect temperatures to stay on the mild
side given the prevailing onshore flow and cloud cover, with highs
generally in the low to possibly mid 80s. Although dewpoints will
almost certainly come down relative to Wed/Thursday just how much is
still a question. Went with a blend this forecast package, however
some of the drier guidance does hint at dewpoints dropping into the
50s for the northern portion of our area on Saturday.

Sunday-Tuesday... Things will likely get more active in this period
as the High to our north moves away and we potentially feel the
influence of both a frontal low to our south and a northern branch
low passing over Canada. Given the uncertainty of how/when these
features would interact and any frontal passages went with a fairly
middle of the road approach for PoPs (generally mid-range Chc) for
Sunday and Monday. Temps should run near or just below climo through
the period. It is possible a more substantial cold front with more
notable postfrontal drying will progress through our area on Tuesday
but there is considerable spread within the guidance on this aspect.

&&

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

Rest of today... Numerous thunderstorms have developed over the
urban corridor and into southern NJ and Delmarva. While prevailing
VFR conditions continue, sub-VFR conditions will occur in any tstms,
mainly through 22z. Storms appear likely to remain southeast of RDG
and ABE. Winds mainly light and variable, but gustier and erratic
winds are possible in the vicinity of any tstms. Moderate confidence.

Tonight... Mainly VFR initially. At least patchy fog and/or low
stratus development is likely again tonight, and have reflected that
in the TAFs. Areas of IFR conditions are likely but it is too early
to pinpoint them. Winds light and variable or calm. Moderate
confidence, except low confidence in how widespread fog and low
stratus will be.

Thursday... Prevailing VFR, however sub-VFR fog or low stratus could
linger through about 14z. Showers and thunderstorms are also
possible again on Thursday, especially near and southeast of PHL.
Winds mainly E at around 5 kt, but may be light and variable or calm
at times. Moderate confidence.

Outlook...

Friday and Saturday... Mostly VFR although some storms will be
possible (mostly on Friday), also can't rule out some restrictions
in lower clouds in the morning. East-northeast winds 5-10kts on
Friday, with easterly winds around 10 kts on Saturday. Moderate
confidence.

Sunday... A chance of showers of thunderstorms in the afternoon.
East-southeast winds 5-10kts. Moderate confidence.

&&

.MARINE...
Through Thursday... Sub-SCA conditions are expected with seas less
than 3 ft. Winds mainly from the S or SW, then becoming SE on
Thursday, with speeds around 10 kt. Areas of fog are possible
overnight. Scattered tstms are possible on Thursday with locally
higher winds and seas.

Outlook...

Friday through Sunday...An increasing onshore flow and building seas
later Friday may require a SCA by Friday night with potential SCA
conditions continuing through Sunday. Thunderstorms are possible
(primarily on Friday), which could produce locally higher winds and
waves.

Rip Currents...

The low risk for the formation of dangerous rip currents is expected
to continue today and Thursday. Breaking waves are forecast to be
less than 2 feet with a medium period swell from the southeast.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flash Flood Watch until 11 PM EDT this evening for PAZ070-071-
     101>104.
NJ...Flash Flood Watch until 11 PM EDT this evening for NJZ016>019-
     021.
DE...Flash Flood Watch until 11 PM EDT this evening for DEZ001>003.
MD...Flash Flood Watch until 11 PM EDT this evening for MDZ008-012-
     015-019-020.
MARINE...None.

&&

Synopsis...Carr
Near Term...O'Brien
Short Term...O'Brien
Long Term...Carr
Aviation...Carr/O'Brien
Marine...Carr/O'Brien

Hazardous Weather Outlook
National Weather Service Mount Holly NJ
340 PM EDT Wed Aug 12 2020

NJZ001-007>010-012-013-015-020-022-023-027-PAZ054-055-060>062-105-
106-131945-
Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-
Mercer-Ocean-Atlantic-Cape May-Southeastern Burlington-Carbon-Monroe-
Berks-Lehigh-Northampton-Upper Bucks-Lower Bucks-
340 PM EDT Wed Aug 12 2020

This Hazardous Weather Outlook is for 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.

There is a low probability for widespread hazardous weather.

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

Thunderstorms Thursday could produce locally heavy rainfall which
may lead to localized flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

DEZ001>003-MDZ008-012-015-019-020-NJZ016>019-021-PAZ070-071-101>104-
131945-
New Castle-Kent-Inland Sussex-Cecil-Kent MD-Queen Annes-Talbot-
Caroline-Salem-Gloucester-Camden-Northwestern Burlington-Cumberland-
Delaware-Philadelphia-Western Chester-Eastern Chester-
Western Montgomery-Eastern Montgomery-
340 PM EDT Wed Aug 12 2020

...FLASH FLOOD WATCH IN EFFECT UNTIL 11 PM EDT THIS EVENING...

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

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

Thunderstorms Thursday could produce locally heavy rainfall which
may lead to localized flooding

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

DEZ004-NJZ014-024>026-131945-
Delaware Beaches-Eastern Monmouth-Atlantic Coastal Cape May-
Coastal Atlantic-Coastal Ocean-
340 PM EDT Wed Aug 12 2020

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

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

ANZ430-431-450>455-131945-
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-
340 PM EDT Wed Aug 12 2020

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

.DAY ONE...This afternoon and tonight.

The probability for widespread hazardous weather is low.

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

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>