Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 241933
Area Forecast Discussion
National Weather Service Mount Holly NJ
333 PM EDT TUE MAY 24 2016
Low pressure near Cape Cod will track northeast overnight into
Wednesday. At the same time, high pressure will shift from the Ohio
Valley to the Eastern Seaboard. A frontal boundary is forecast to
settle across the Northeast and northern Mid-Atlantic Thursday
through Monday. High pressure is expected on Tuesday.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Low will continue to lift away from the region overnight leading to
clearing skies. Removed mention of fog overnight as we have already
seen dew points drop into the 30s in the Poconos, and the dry air
advection should continue through the remainder of the day. Even
with many locations near 80 this afternoon, still expecting
temperatures to drop into the 50s overnight thanks to prime
radiational cooling conditions.
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
The big story tomorrow will be a dramatic warming trend as the
ridge axis slides closer to our region. Have gone slightly above
the highest guidance for max temps tomorrow given that the models
have recently had a cold bias. With large 1000-500mb thickness
increases and mostly clear skies, there are several factors
promoting a warming trend and only one factor - a sea breeze, if
it develops - that could temper the highs.
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Overview...the period will be dominated by an east coast ridge and
west coast trof aloft and a weak surface front that is forecast to
meander across the Northeast and northern Mid-Atlantic through
Monday. The front could sag as far south as northern PA and NJ from
time to time and help to trigger showers and thunderstorms as well
affect temps with a stronger onshore flow on the northern side of
it. A washout is not anticipated, but with the front in place
combined with afternoon instability, some locales will get wet.
Temps...Normals for PHL through the period are in the mid 70s and
mid 50s. With 925 temperatures rising at or above 18 degrees C
through Sunday (we`re about 13 degrees C this afternoon), an
extended period of above normal temps can be expected. On Monday and
Tuesday, a slightly cooler synoptic airmass is forecast to arrive.
An onshore flow could also help to lower temps.
Temps are going to be the warmest across the interior, with highs
about 10 degrees above normal through Sunday, cooling Monday and
Tuesday. Along the coastal plain, temps will rise into the mid to
upper 70s through Saturday. Sunday is expected to be cooler closer
to the ocean as a more onshore gradient develops. Right along the
beaches and boardwalk, a chilly seabreeze can be expected each
afternoon through Saturday with water temps still in the 50s and
the interior forecast to be in the 80s. Sunday through Tuesday,
beach temps should be cooler altogether with a more persistent
Keep an eye on the surface front to our north. If the surface high
building across Quebec is stronger than expected, the front could sag
further south and cool temps to levels that are lower than what`s
forecast. The further south one goes along the NJ coast and along
the DE beaches, confidence is higher that the front will be a non-
Precipitation...with the front just to our north or in our vicinity,
combined with climbing dewpoints (up to the mid 60s) and
instability, afternoon showers and thunderstorms could pop any day
across the interior through Saturday. A washout is not expected.
We`re talking about isolated to scattered POPS common in a
summertime regime. Precip chances spread to the coast on Sunday and
Winds...mainly from the south or southwest through Saturday and less
than 15 mph. Winds could turn more easterly on Sunday, more likely
on Monday and Tuesday. With ocean temps in the 50s and the I95
forecast to be in the mid 80s, a seabreeze will no doubt develop and
push inland. So during the afternoon hours through Saturday, winds
are forecast to become more southeast to east.
Hazards...The probability for widespread hazardous weather is low
through the period.
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Mostly VFR conditions are expected through the TAF period. Isolated
showers and thunderstorms are possible through 22Z. However, have
not included this in most of the TAFS as the limited coverage means
that there is low confidence that any one TAF site will be affected.
Winds will be generally shifting between northwesterly and
southwesterly though direction could be variable between 00 and 12Z
as winds become light.
Wednesday night...VFR. West to southwest winds up to 10 knots.
Thursday through Sunday...VFR overall, however brief times of
MVFR/IFR conditions are possible each afternoon and evening due to a
few showers and thunderstorms, especially across the I95 terminals
westward. South to southwest winds 15 knots or less. A seabreeze
front in expected to track westward through the afternoon hours, so
a turn to the southeast should result where the seabreeze front
Winds may gust above 20 kt at times this evening on the southern
coastal waters, but winds and seas are expected to stay below SCA
criteria tonight and tomorrow.
Wednesday night through Sunday...A ridge aloft over the area
combined with high pressure at the surface to our south and east
will allow for mainly a prolonged southerly flow across our area,
potentially through Saturday night. Winds could back more onshore on
Conditions are expected to be below Small Craft Advisory criteria
through the period. Seabreeze circulations are expected to develop
each day, so an increase in winds can be expected along with a bit
of chop across the nearshore waters during the afternoon hours.