Area forecast discussion
National Weather Service Mount Holly New Jersey
405 am EDT Wednesday may 22 2013
Synopsis...
high pressure will remain anchored off the southeastern United
States coast through Thursday. Low pressure will approach from the
west, passing to our north, and will drag a cold front through the
region late Thursday into Friday. Canadian high pressure will then
build into the region for the Holiday weekend and last into early
next week.
&&
Near term /until 6 PM this evening/...
low clouds and fog will be in place to start the day once again
today. This should burn off/lift by middle-morning, but we should
continue to have a partly cloudy day.
High pressure remains off the southeast coast today, while low
pressure moves into the Great Lakes region. This will keep a
return flow across the area, continuing to keep warm, moist air
flowing across the region. Temperatures today should generally
reach the middle-upper 80s across much of the area; the coastal strip
should remain cooler, and probably not reach 80.
With the warm, moist airmass remaining in place, there will continue
to be quite a bit of instability across the area. The limiting
factor for showers/thunderstorms will be a slight cap, and lack of a
strong short wave/vorticity maximum. However, there could be some weak
vorticity aloft moving through later in the day, which could help
spark off some showers/thunderstorms. The greatest chance for
activity looks to be north and west of the I-95 corridor. Any
showers/thunderstorms that do develop could contain heavy rain as
well as gusty winds and even some small hail.
&&
Short term /6 PM this evening through 6 am Thursday/...
a couple of rounds of showers/thunderstorms look possible overnight
Wednesday into Thursday morning. The first round looks to be early
in the evening associated with short wave/vorticity maximum moving through
late in the day and into early evening. We may then get a break for
a portion of the overnight, followed by another possible chance of
precipitation closer to sunrise Thursday. This would be associated
with a second short wave/vorticity maximum moving through.
With dewpoints remaining elevated across the area, overnight lows
will remain high. Generally temperatures are expected to only drop
into the middle-upper 60s.
&&
Long term /Thursday through Tuesday/...
with high pressure sitting to our southeast, we will continue to
see a south to southwesterly flow which will continue to advect
warm and moist air to our area. This will keep our temperatures at
or above normal for Thursday.
A low pressure system will approach from the west on Thursday, with
the center passing off just to our north. The attached cold front is
forecast to move through our area Thursday into Friday, most likely
later in the day Thursday into early Friday. The latest model
guidance continues to slow down the frontal passage and also starts
to develop a middle level feature along the middle-Atlantic coast. With
precipitable water values around 1.5 inches, any slowing of the
frontal passage may end up contributing to flooding as heavy rain
will be possible. This will need to be monitored, especially for the
areas with lower ffg values, mainly across central and northern New
Jersey.
Showers and thunderstorms may develop ahead of the front on Thursday
as surface heating and some weak instability will be in place. While
the severe threat does not look to be all that great at this time,
there is a chance that some storms may become strong and Storm Prediction Center has
highlighted our area in their day 2 outlook with a see text.
The front pushes through and offshore on Friday morning. Some
lingering showers may continue through Friday morning but overall
the areas should dry out by Friday afternoon. Cooler air will be
pushed into the region on a northwest flow and temperatures will
fall below normal for Friday. Highs will generally be in the upper
60s to lower 70s.
Canadian high pressure will build into the region behind the front,
bringing in some cooler and drier air for the Holiday weekend and
into early next week. The models hint at a shortwave moving through
the middle levels on Saturday and another one on Sunday. The airmass
looks to be too dry for anything to make it to the surface and we
have kept the Holiday weekend and early next week dry. Temperatures
will remain below normal through the early part of the week with
highs in the upper 60s to lower 70s across the region. Temperatures
will gradually start to warm toward the midweek time frame.
&&
Aviation /08z Wednesday through Sunday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
A brief period of MVFR/IFR ceilings/visibilities are expected again early this
morning. Any low clouds/fog that does develop should burn off/lift
by mid-morning. VFR conditions should then remain across the taf
sites for the remainder of the day and into the evening hours. There
is the chance for scattered showers/thunderstorms this afternoon.
The greatest potential looks to be for our northwestern tafs. The
overnight 06z tafs did not include shower/thunderstorm potential,
however, the 12z tafs may be updated to include a tempo shower group
for late in the day. Confidence in thunderstorms occurring would be
low enough not to include. Winds today may gusty around 15-20 knots
after the sun breaks out and some mixing occurs during the afternoon.
Low ceilings/visibilities are once again forecast for Wednesday night/Thursday
morning with the moist airmass in place. There is also the potential
for some showers, but timing these is difficult, so they were left
out for now.
Outlook...
Thursday and Thursday night...mainly VFR. MVFR, possibly IFR,
conditions possible in any showers and thunderstorms or heavy rain.
Friday...mainly VFR with a chance of showers mainly in the morning.
Northwest winds 10 to 15 knots.
Saturday and Sunday...VFR. Northwest winds 15 to 20 knots.
&&
Marine...
south-southwest flow will remain across the waters today and
tonight. The gradient may tighten some late today into tonight, and
winds may gust close to 25 knots. Wavewatch has been running a
little high, but even if we knock a foot off of the seas, 5 foot
seas could start late today into this evening. Therefore a Small
Craft Advisory has been issued starting late this afternoon and
continuing into at least tonight.
Outlook...
high pressure anchored off the southeastern United States coast will
continue to bring a to southwest flow through Thursday on the area
waters. Small craft conditions are expected to continue on Thursday.
The cold front will cross the area waters late Thursday into Friday.
The pressure gradient will tighten as the front departs to the east
and high pressure starts to build down from Canada. This may cause
winds to gust up around 25 knots, especially on Saturday. Seas will
likely remain at or above 5 feet into the early part of the weekend.
Both winds and seas are expected to subside by late Saturday and
then remain below advisory criteria through the rest of the Holiday
weekend.
&&
Climate...
knowing the first 20 days of may temperatures have averaged almost
spot-on normal for almost every climate site in our area...we
projected the remainder of the month for kphl. We used the kphl
maximum/mins for the next 7 days, and then the ftprha phl 2m maximum/min
temperatures beyond through the 31st.
The projected monthly average temperatures is in the normal range...slightly above
but within 1/2 degree of normal.
We discuss temperatures tonight since we're coming into the Memorial Day
weekend which will be cool and less favorable for ocean swimming but
guidance is showing increasing chances for a warmer than normal
pattern developing here between roughly the 30th of may well into
the first week of June.
Sst's are already generally several degrees above normal. If we
advance into a hot spell by the end of next week...we do not want
a repeat of last year when hot weather...warmer than normal waters and
seemingly benign ocean swells encouraged swimmers to take unnecessary
risks at early season "unguarded" beaches with rip current related
drownings. The dangers of rip currents are worthy of a few minutes
of dinner table discussion...especially since there is access to
the beaches for millions of swimmers over interior sections of our
area who may be less experienced with the dangers of ocean swimming.
The chances of drowning at a life guarded beach is 1 in 18 million.
Rip current awareness week is June 2 through 8.
&&
Phi watches/warnings/advisories...
PA...none.
New Jersey...none.
Delaware...none.
Maryland...none.
Marine...Small Craft Advisory from 5 PM this afternoon to 6 PM EDT
Thursday for anz450>455.
&&
$$
Synopsis...meola
near term...Robertson
short term...Robertson
long term...meola
aviation...Robertson/meola
marine...Robertson/meola
climate...
