Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 281513
Area Forecast Discussion
National Weather Service Mount Holly NJ
1113 AM EDT TUE JUN 28 2016
Cold front will approach the region later today. It is expected to
slowly drift east offshore on Wednesday. High pressure builds in for
Thursday, before another cold front is expected to approach the
region late in the day on Friday. High pressure should build in for
the remainder of the weekend, before a warm front lifts into the
region Monday or Tuesday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The showers/isolated thunderstorms associated with the initial
short wave/vorticity impulse across southern New Jersey and
Delmarva have mostly moved south of the area and offshore. There
does remain some some showers/isolated thunderstorms across far
southern Delaware that will hang around into the early afternoon
however. For the rest of the area, we will be mostly
precipitation free for a few hours, outside of an isolated shower
or sprinkle. Clouds will hang around through the day, but some
breaks should begin developing in the cloud cover from west through
Eventually, the cold front to the west will overtake the lee side
trof that`s across our western areas, while the next short
wave/vorticity impulse approaches as well. This will lead to
another round of showers and thunderstorms developing to our west
and moving into our area later afternoon and into this evening.
SPC still has the Poconos, the Lehigh Valley, and northwest NJ in
a slight risk. Marginal is surrounding the slight risk. Higher
POPS, in the likely category, remain for the mid-afternoon across
the northern and western zones and drift south and east to finish
off the period.
Gusty winds, small hail, and heavy rain can be anticipated today
with the heavier showers and thunderstorms, even though PW`s will
be decreasing across most of the CWA today. The exception will be
the Delmarva. This is a good thing because soundings don`t suggest
the showers and thunderstorms will be moving at a quick pace.
Still, ponding in low lying or poor drainage areas could very well
Normals for KPHL today are 86 and 67. We will probably run just a
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
The question for tonight will be how far east the cold front gets by
daybreak Wednesday. The 00z models did offer some quicker/slower
solutions. As far as how this relates to any precipitation. We`ll
start the northern half of the CWA with likely POPS. Slightly less
further south. This will transition into chance and slight chance
POPS, along with some fog, by 6 AM Wednesday.
With the front dropping through our northwest zones, temps should
drop into the mid 50s to lower 60s. Further south and east where the
front still has a presence, 60s will be the rule. The front should
be right along the coast early Wednesday morning.
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Wednesday...Question this day will be where the front stalls. The
GFS has it offshore by 12Z Wednesday morning, while the ECMWF and
NAM are not quite as progressive. For now, have favored the slower
solutions given the upper level short wave trough will still be
lagging behind the surface front until at least mid day Wednesday.
Wednesday night through Thursday night...High pressure briefly
builds in, in the wake of the cold front. An inverted surface
trough may develop by Thursday...resulting in low level southerly
flow, warm air advection, and moisture advection. As this
continues Thursday night, could see some showers and thunderstorms
as a mid and upper level jet develops just northeast of the
region, which may leave our region under the right rear quadrant.
Friday and Saturday...next cold front and associated upper level
short wave trough sweep through the region. Unlike the early week
front, models depict this front sliding through the region rather
quickly, with the possible exception of Delmarva. Given the time
of year, and a lack of any strong pressure rises behind the front,
am not confident that this front will clear the region as quickly
as most models are depicting. Thus, given the uncertainty, kept
close to the previous forecast.
Sunday through Independence Day...Weak high pressure should build
in for Sunday and Independence Day. Thus at this point, we still
expect this period to be dry (once lingering showers and
thunderstorms on Sunday morning across the south move out of the
Tuesday...Depending on how quickly the high shifts off shore, low
level flow will shift to southerly sometime on Tuesday, bringing
warm air and moisture advection. No especially distinct features
to suggest widespread precipitation at this point, however.
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Today...mainly IFR to MVFR with ample low-level moisture. There
could be a transitions to some VFR later this afternoon,
especially across the northern half of the area. The first round
of showers have moved south of the TAF sites this morning. The
second round of showers and possible thunderstorms are expected to
develop to our west and move into our area later this afternoon
and into this evening. Winds will be mainly from the south-southeast
less than 10 kts.
Tonight...More of the same with at least MVFR conditions. Much of
the precip should come to an end late. South winds will veer to the
west as the front tracks through, but speeds should be less than 10
Wednesday through Thursday...After any MVFR ceilings move offshore
with lingering showers Wednesday morning, VFR conditions are
Thursday night through Friday...MVFR and brief IFR conditions will
be possible with any showers and thunderstorms that move through
the region during this time.
Saturday...mostly VFR conditions are expected.
Today and tonight...No headlines, although south winds will be in
the 10 to 15 kt range with gusts up to 20 kts. Showers and
thunderstorms will be likely this morning across the southern
waters. A better shot of showers and thunderstorms will be again
possible this evening and portions of the overnight, more so
across the northern waters.
Wednesday through Saturday...winds and seas should remain below
SCA criteria. Although gusty winds are possible in the vicinity of
any thunderstorms Thursday night or Friday.
RIP CURRENTS...We will go with a low risk for the development of rip
currents for Delaware and a moderate afternoon risk for New Jersey.
The rip current risk will be low to possibly moderate at times
during the balance of this week, in part dependent on the amount of
onshore wind. In other words, not much change from the somewhat
active month of June. AWARENESS: weak swimmers for their own safety
should swim only in the presence of lifeguards. It is not worth
being a rip current victim by swimming near jetties, or after the
lifeguards go home, or with untrained weak swimming bystanders who
wont be capable of saving a distressed swimmer, except to call 911,
which then could be too late.