Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 161549
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1149 AM EDT Wed Aug 16 2017

.SYNOPSIS...
High pressure will build across the region today before moving
offshore on Thursday. A warm front will lift northward towards the
area late Thursday and then moves through the area on Friday. A cold
front will approach from the west on Friday, pushing through the
region Friday night through Saturday. High pressure returns for
Sunday through Tuesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast remains on track through the early afternoon hours.
Weak shortwave as seen in water vapor image tracking across
southern PA, and should pass through the region late
afternoon/early evening. 12Z NAM and latest HRRR showing some
precip popping up, but think best chances will be across
southeast NJ and DE. Will bump up PoPs a bit, mainly to slight
chance, for a few hours this afternoon and evening, as a few
isolated showers are possible with its passage.

Light northwest wind trends west during the afternoon with sea
breezes along the coast.

Max temps a couple of degrees above normal.

High Risk for dangerous rc formation continues per the 13
second 4-5 ft se swell from Gert, washing ashore.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
Again, its not impossible to see isolated sprinkles vcnty
Philly to ACY at 00z down into s DE but not lasting long.

Otherwise becoming mostly clear.

The wind shift progresses southward to near PHL by 12z Thursday.
Light north-northeast wind to its north and and light south to
southwest to its south.

Cooler and much more comfortable I78 northward, though short
lived.

Patchy fog probably forms toward dawn Thursday, but not nearly
to the extent we see it this morning and not expecting a dense
fog advy situation.

Forecast basis was a 50 50 blend of the 00z/16 GFS/NAM MOS
guidance.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
High pressure will start to slide offshore on Thursday with a warm
front developing across Virginia. The warm front will push northward
on Thursday and will start to move into our area late Thursday,
pushing through the region on Friday. Showers and thunderstorms will
start to develop just north of and along the warm front on Thursday
afternoon and evening and then will overspread the region Thursday
night and Friday as a warmer and moister airmass moves into the Mid-
Atlantic.

A cold front will approach the region from the west on Friday,
crossing the region late Friday through Saturday. Another round of
showers and thunderstorms are expected as the front moves through
our area. Good shear and forcing across the area means some
storms may be strong, possibly severe, and with PWATs running
high again, heavy rain will also be a threat. SPC has a marginal
risk for severe storms just to our west at this time.

Some cooler air should arrive behind the front but it isn`t all
that cool or dry so little relief is expected. A shortwave will
cross through the region on Saturday keeping the chance for
showers and thunderstorms throughout Saturday evening. As the
wave pushes to the east, the showers/thunderstorms will decrease
in coverage and drier air will start to move in.

High pressure will build in for Sunday and a period of relatively
nice weather should continue for the start of the week with the high
shifting offshore on Monday. Another frontal system will approach
the region for Tuesday/Wednesday with another chance for showers and
thunderstorms.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

VFR sct-bkn clouds aoa 4000 ft develop midday with a west-
northwest wind trending west to southwest late in the afternoon
except sea breezes developing vcnty KACY. Isolated light showers
possible se PA to s NJ after 21z. I think the NAM tsec is best
for fcstg low lvl rh changes. NARRE has completely missed the
dense fog in our area, yet unexpectedly to me has a stratus deck
lingering to around 15z.

Tonight...After any isolated light showers vcnty KILG/KPHL/KACY
southward end by 01z, a VFR night with a wind shift progressing
southward to near KPHL by 12z Thu. Winds turn light north-northeast
north of the boundary and are light south to southwest to its
south.

Patchy IFR fog/stratus may form in the NJ and Delmarva countryside
between 07z-10z/17, but not nearly to the extent of what we see/saw
this morning.

OUTLOOK:
Thursday...Mainly VFR conditions expected. Sub-VFR conditions in
afternoon/evening showers and thunderstorms. Fog possible early
Thursday morning and again late Thursday night.

Friday...Fog possible early morning. Sub-VFR conditions in showers
and thunderstorms.

Saturday...MVFR conditions expected Scattered showers and
thunderstorms possible. Improving conditions late.

Sunday...Mainly VFR conditions expected.

&&

.MARINE...
44009 has dropped to 3.6 feet this past hour, and was down to
3.3 ft the hour before. Will go ahead and cancel the SCA for
ANZ454-455, and will extend SCA for ANZ450-453 until 4 pm as
seas look to remain right around 5 ft into this afternoon.

Light northwest flow becomes southeast to south sea breezes
during this afternoon. A wind shift back to northerly should
develop for the NJ coastal waters late Wednesday night.

OUTLOOK...

Thursday thru Sunday...Sub-Small Craft Advisory conditions
expected on the area waters through Sunday. Some gusts around
20-25 knots are possible Friday afternoon and evening. Showers
and thunderstorms possible late Thursday through Saturday, with
locally higher seas and winds.


RIP CURRENTS...
A high risk for the development of dangerous rip currents is
in effect today. Long period swells from Hurricane Gert will
continue to impact the coasts of Delaware and New Jersey.

Swim only in the presence of lifeguards where safety prevails
and if beaches are closed...respect the decisions of the local
officials. Do we need a reminder? There have been numerous
drowning fatalities this year along the NJ coast, and most of
those at unguarded beaches.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...High Rip Current Risk until 9 PM EDT this evening for NJZ014-
     024>026.
DE...High Rip Current Risk until 9 PM EDT this evening for DEZ004.
MD...None.
MARINE...Small Craft Advisory for hazardous seas until 4 PM EDT this
     afternoon for ANZ450>453.

&&

$$
Synopsis...Meola
Near Term...Drag/MPS
Short Term...Drag
Long Term...Meola
Aviation...Drag/Meola/MPS
Marine...Drag/Meola/MPS



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