Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 232327
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
727 PM EDT MON MAY 23 2016

.SYNOPSIS...
The low offshore will begin to lift northeast away from our
region tomorrow. In the wake of that low, a ridge will build over
our region Wednesday and Thursday. The ridge will slowly shift
east through the remainder of the week. A few small troughs around
the edge of the high will keep unsettled summer like conditions
for through the weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
The early evening forecast was updated to account for the latest
trends in radar, mesoanalysis and short-range forecasts from
convection-allowing mesoscale models for tonight. The bulk of the
convective activity this afternoon and currently as we approach
sunset was confined along a corridor of relatively greater
instability (owing to stronger heating in the afternoon and
moisture pooling that developed) along and just west of the I-95
corridor. Convection as seen on radar has weakened over the past
1-2 hours and will continue to dissipate after sunset as the
boundary layer stabilizes from the loss of solar heating. There
will still be some showers focused along the I-95 corridor and
Delmarva thru the remainder of the evening. The shower activity is
expected to shift toward the coast overnight into early Tuesday
morning as the coastal low and upper low both move northeastward.

Previous Discussion...
The surface is located to the southeast of the area and will make
its way north and then east through tonight. The upper level low
is located just off the Carolina coast and gradually pushing
eastward. As the upper low pushes east, it will help to move the
surface low away from our area.

Scattered showers and thunderstorms have developed across the region
this afternoon. As we head into this evening, these showers will
weaken and dissipate from west to east. The cumulus will start to
dissipate as we lose prime surface heating but cirrus will continue
to push in from the east. While skies may start to clear, we
anticipate that there will still be decent cloud cover overnight.

In areas where we see rain this evening, we may start to see some
fog development overnight as winds will go light and variable. If
the clouds clear more than expected, fog may become more
widespread across the region.

Temperatures are expected to fall into the 50s across the region
overnight.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
The upper low makes it way away from the eastern seaboard on
Tuesday. The surface low will also make its final push off to the
east of the area. Some energy rotating through the flow will help to
spark some showers on Tuesday, possibly an isolated thunderstorms as
well. We should start to dry out from southwest to northeast as we
head through the afternoon and into the evening.

Temperatures will be closer to normal with highs into the 70s
through much of the region. Areas along the coast may remain closer
to the upper 60s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Wednesday and Thursday...Upper level ridge will shift east, with
the ridge axis over our region by Thursday morning. If the
departing upper level low is slower to lift away from the region
than expected, the ridge may flatten a bit as the axis approaches
our region. The few models that are depicting this pattern are
showing showers across the Poconos and NW NJ late Wednesday as the
ridge weakens. For now have kept Wednesday and Wednesday night dry
as even if the ridge weakens slightly, there should be
considerable synoptic scale subsidence over our region. Once the
ridge axis shifts east of our region by late Thursday, we`ll be
close enough to the periphery of the ridge that we could begin to
see primarily diurnally driven showers and thunderstorms,
initially confined to the NW portions of our region. Of more
certainty is that the region will have a very noticeable warming
trend, with 80s expected across much of the region both days.

Friday through Monday...There continues to be poor model agreement
and run to run consistency through this period, primarily as it
relates to a backdoor cold front in the region Friday or Saturday.
Most model solutions keep this front north of the region, but a
few models and ensemble members bring it as far south as our
region. If this scenario is correct, persistent onshore flow could
result in temperatures well below normal especially Saturday and
Sunday, and generally light and steady precip through much of the
period. For now though, have not included this in the forecast, it
seems an unlikely pattern for late May that a cold front would be
able to push this far south under an upper level ridge. Even with
models and ensemble members that show the ridge lingering over the
region, should still see chances for showers and thunderstorms
through the weekend as the region could be on the periphery of the
ridge.

&&

.AVIATION /23Z MONDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Through tonight...Showers are popping up across the region this
afternoon with some isolated thunderstorms affecting the terminals.
As we head into tonight, the showers and thunderstorms are expected
to dissipate from west to east.

Winds will become light overnight and skies may even start to clear.
Should clearing occur, some fog will be possible especially in areas
where low level moisture has increased due to precipitation. We have
included some 4-6sm fog in the taf during the overnight/early
morning hours.

Tuesday...mainly VFR conditions are expected across the region. Any
fog should clear between 12-14z. Another round of scattered showers
is possible and even a few thunderstorms may occur. All activity
will decrease as we head towards the late afternoon/evening. Winds
will turn to the west for Tuesday.

Outlook...

Wednesday...VFR conditions expected.

Thursday through Saturday...Intermittent MVFR conditions with
showers and thunderstorms possible each day.

&&

.MARINE...
The Small Craft Advisory was cancelled farther north for the
Coastal Atlantic zones of southern NJ with seas subsiding to near
4 ft. The Small Craft Advisory was converted to a Small Craft
Advisory for Hazardous Seas for the Coastal Atlantic zones south
of Cape May with seas expected to remain near 5 ft thru midnight
or shortly after in response to an offshore surface low. As the
low moves north tonight and then pulls away to the east, seas will
start to subside.

Outlook...

Wednesday through Saturday...winds and seas should stay below SCA
criteria.

RIP CURRENTS...
There is a moderate risk of rip currents at the Delaware Beaches
through this evening.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory for hazardous seas until 2 AM EDT Tuesday
     for ANZ454-455.

&&

$$
Synopsis...Johnson
Near Term...Klein/Meola
Short Term...Meola
Long Term...Johnson
Aviation...Johnson/Meola
Marine...Johnson/Klein/Meola



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