Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
937 PM EDT Monday Jul 6 2015
a warm front is forecast to lift northward through our region
from tonight into Tuesday morning. Another frontal boundary is
expected to arrive from the northwest on Wednesday. The front is
anticipated to meander in our vicinity from Wednesday night
through Thursday night as weak areas of low pressure move along
it. The front is forecast to move to our south for Friday and for
the weekend, allowing high pressure to nudge down from the
northwest and north. The boundary may return as a warm front early
Near term /until 6 am Tuesday morning/...
most of the earlier convective activity has started to wane.
However, the upper level low is forecast to open and move towards
the northeast late tonight. Our northwestern zones will still have
the better chances for showers through the overnight hours, even
with the lack of instability...ill-defined cold core aloft, but
does not appear cold enough for stronger updrafts.
Overnight temperatures will drop back into the upper-60s to low-
70s as dew points remain quite moist across the region. This will
setup pockets of fog, not sure how dense at this time, with the
prolonged onshore flow in place.
Short term /6 am Tuesday morning through 6 PM Tuesday/...
as one middle-level wave moves out there is another one right on its
tails. Timing is still a bit suspect but it appears that the middle
to late afternoon time period is when the better chances for
showers exists...peak heating, and mostly across our northwestern
zones. By the time we will be in the warm sector, as the warm
front from Monday continues to lift towards the north-northeast.
Precipitable waters should be at their highest, around 1.75-2.00 inches, so any
of the showers will become heavy rainers. Temperatures will be
several degrees warmer with the addition of a more westerly
surface flow component so we could reach 90f in and around the
philly metropolitan area tomorrow afternoon.
Long term /Tuesday night through Monday/...
the middle level flow is expected to remain somewhat zonal east of
The Rockies from Tuesday night through Wednesday night as low
pressure meanders off the California coast, moves inland and
fills. The model guidance is trending toward greater amplification
of the middle level pattern over the central and eastern states late
in the week with ridging developing over the Great Lakes.
Eventually, a long wave ridge is anticipated to return over the
Rocky Mountain states during the weekend with a trough settling
over the east.
A middle level short wave trough is forecast to be pulling away from
our area on Tuesday evening. Any residual showers and
thunderstorms should come to an end at that time. A break in the
precipitation potential is anticipated for much of Tuesday night
into early Wednesday.
It continues to appear as though a frontal boundary will drop
into our region on Wednesday and it should remain across our
forecast area through Thursday night. The nearly zonal flow will
make it difficult to time any middle level impulses and associated
weak surface waves. Regardless, a chance of showers and
thunderstorms will exist through that period of time. The guidance
is suggesting that a middle level short wave trough and weak surface
low may pass across our forecast area on Thursday night pulling
the surface boundary to the south of Maryland and Delaware.
Precipitable water values are forecast to rise near or above 2
inches during the middle week period in much of our region. Any
thunderstorms could bring heavy downpours along with localized
flooding of roadways and areas of poor drainage. Also, we will
keep an eye on the flash flooding potential especially if certain
areas are affected by heavy rainfall on more than one day.
The amplifying middle level flow should allow high pressure to work
its way toward our region from the northwest and north for the
coming weekend. As a result, we will not indicate a chance of
showers and thunderstorms for that period of time.
We will forecast a returning chance of showers and thunderstorms
for early next week with the surface boundary expected to return
northward as warm front.
Daytime temperatures are anticipated to be within a few degrees
of normal for the period from Tuesday night through Monday.
Nighttime temperatures are forecast to be above normal.
Aviation /02z Tuesday through Saturday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
VFR conditions will lower to MVFR for much of the region near or
after 06z. There remains a small chance for showers overnight, but
coverage is too limited to mention in the tafs at this time. The
larger story will be with a slight on shore component in the
winds, br or fog is expected to develop after 06z. At this time,
it looks like kabe and krdg have the highest risk of IFR
conditions, with mostly MVFR conditions expected elsewhere.
Tuesday...as the wind shifts more westerly, conditions should
gradually improve to VFR between 12 and 18z. More scattered
showers are possible during the afternoon, but mostly north of
Tuesday night and Wednesday morning...conditions possibly
lowering to MVFR or IFR in low clouds, haze and fog especially
during the late night and early morning hours.
Wednesday afternoon through Thursday night...a chance of showers
and thunderstorms which may cause conditions to lower to MVFR or
IFR at times.
Friday through Saturday...mainly VFR.
sub-Small Craft Advisory conditions expected tonight and tomorrow with
southeasterly winds veering towards the south-southwest by Tuesday
afternoon around 15 knots. Seas will increase upwards of 4 feet by
Tuesday afternoon as well.
Tuesday night through Saturday...no marine headlines are