Area Forecast Discussion
Issued by NWS Mt. Holly, NJ-- Remove Highlighting --
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FXUS61 KPHI 230349
Area Forecast Discussion
National Weather Service Mount Holly NJ
1149 PM EDT SUN MAY 22 2016
Low pressure continues to develop off of the North Carolina coast
overnight, which will then slowly drift northeastward and linger
just offshore of our region through Tuesday. A ridge will build
over our region by mid week, then it will slowly shift eastward
through the remainder of the week.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A developing closed low centered to our southwest will pivot
southeastward overnight. This places our area on the northern side
with much of the forcing being pulled to our south. As a result,
some lingering showers across mainly our southern zones should be
pushed farther south. Some showers off the central New Jersey coast
are tending to weaken as they slowly move westward. Otherwise,
breaks in the cloud cover continues to occur and this is already
leading to some shallow fog development in open areas such as
fields. This is expected to continue, however the extent of the fog
will depend on the coverage of mid/high clouds.
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
A low pressure system will start the day to our southeast and move
northeast toward Cape Cod by nighttime. While the system will be
offshore, daytime heating will result in some instability by the
afternoon hours. This will likely result in another round of
scattered showers forming and even some thunderstorms with CAPE
values of a few hundred J/KG. The highest chances look to be across
Eastern PA where the terrain may help out a little as well.
Temperatures should rise into the low and mid 70`s for the region
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Tuesday...the upper level low will linger over the northeastern
U.S. for one more day before lifting further northeast. As such,
should see any lingering showers across the region taper off by
the evening. A modest warming trend is expected going into Tuesday
resulting in temperatures once again near normal.
Wednesday and Thursday...Upper level ridge will shift east, with
the ridge axis over our region by Thursday morning. However,
unlike previous model runs, the 12z ECMWF and GFS now show the
center of the high much further south. As such, though there
should be a lull in rain chances on Wednesday, rain chances will
increase once again on Thursday, primarily for locations expected
to be west of the ridge axis (Generally E Central PA and NW NJ).
Of more certainty is that the region will have a very noticeable
warming trend, with 80s expected across much of the region both
Friday through Sunday...The GFS has poor run to run consistency
through this period, as it now shows a backdoor cold front
arriving in the region by Friday. 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, not only due to the poor
run to run consistency, but also because 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 /04Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Overnight...VFR overall as some lingering showers have shifted south
of KMIV. Some fog development is expected, especially where the
clouds thin out more. Some light fog has been included for all TAF
sites, with the lowest restriction potential at KRDG. Light winds.
Monday...MVFR/IFR visibility due to fog early for some terminals,
otherwise VFR. Showers are expected to develop from about midday
on, with the greatest chance from KTTN-KPNE/KPHL-KILG on westward.
A few thunderstorms are anticipated as well. Given low coverage of
thunderstorms it was not included in the TAF`s. Light and variable
winds to start, becoming mostly northeast 4-8 knots then possibly
becoming southeast toward evening.
Monday night...Local restrictions due to showers or a
thunderstorm in the evening, however the showers should be
diminishing through the night. Otherwise, mainly VFR. Light
southerly winds overall, which if enough clearing takes place
overnight then local fog should develop.
Tuesday...Occasional MVFR conditions possible with showers and fog
especially Tuesday morning.
Wednesday and Thursday...VFR conditions likely. Small chance of MVFR
conditions with showers and thunderstorms Thursday afternoon and
Friday...Intermittent MVFR conditions with rain showers possible.
SCA tonight through late tomorrow afternoon on the ocean. While
winds will generally be northeasterly from 10-15 knots, seas will
remaining around five feet through tomorrow afternoon on the ocean
waters. Seas will likely be slower than wavewatch indicates coming
down because of an easterly, onshore flow component in the wind
direction. However, it is still expected that seas fall below five
feet by days end on Monday.
Tuesday through Friday...winds and seas should stay below SCA
MARINE...Small Craft Advisory until 6 PM EDT Monday for ANZ452>455.
Small Craft Advisory until 6 AM EDT Monday for ANZ450-451.