Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
334 PM EDT sun Jul 5 2015
weak high pressure that was located overhead today will pass off
the coast for tonight and Monday. A warm front is forecast to lift
northward and through our region from Monday night into Tuesday
morning. Another frontal boundary is expected to arrive from the
northwest on Wednesday. The front is anticipated to meander in or
near our region from Wednesday night into Friday as low pressure
moves along boundary. Weak high pressure may try to build down
from the northwest and north for next weekend as the frontal
boundary remains nearby to our south.
Near term /until 6 am Monday morning/...
weak high pressure will move offshore. As it does wk, low pressure coupled
with wm advection will bring an area of showers and some embedded
thunderstorms and rain toward the region from the SW. By daybreak there could be some
precipitation over the Delaware-Maryland-Virginia. Otherwise most locations will be dry
through the night. Temperatures look to be in the middle to upper 60s.
Short term /6 am Monday morning through 6 PM Monday/...
the aforementioned area of showers will bring the best chances of
rain to the Delaware-Maryland-Virginia and western sections of the area during the day on
Monday. It is possible that eastern areas remain dry, but will carry low very
low probability of precipitation in these locations, in case some showers do make it into
these places. Overall quantitative precipitation forecast appears to be low. High temperatures will be in
the middle to upper 80s.
Long term /Monday night through Sunday/...
the middle level ridge that was over the western states is forecast
to disappear for the new week as low pressure meanders off the
California coast, moves inland and fills. The middle level flow east
of The Rockies is expected to become somewhat zonal, resulting in
another potentially active week for our region. The western ridge
is anticipated to return next weekend.
It continues to appear as though a wavering frontal boundary to
our south will return northward as a warm front on Monday night.
The boundary is expected to pass through our region from Monday
night into Tuesday morning. As a result, we may see some low
clouds and patchy fog and haze, along with a chance of showers or
A middle level short wave trough is forecast to be located over the
upper Ohio River valley and vicinity on Monday evening. The
feature will drift eastward and it is expected to pass over our
region on Tuesday afternoon. The increase in moisture and the
development of instability due to daytime heating along with the
middle level trough passing overhead could result in the development
of scattered showers and thunderstorms on Tuesday afternoon. The
greatest potential appears to be in eastern Pennsylvania and
northern and central New Jersey where mixed layer cape values are
forecast to rise around or just above 1000 j/kg.
The timing of additional impulses in the nearly zonal middle level
flow during the middle and late week period becomes a bit of a
challenge after the initial middle level trough passes on Tuesday
afternoon. While it seems that convection will occur in parts of
our area on Wednesday, and perhaps on Thursday and Friday, as
well, the exact location of the greatest potential remains a low
Presently, it looks as though our highest chance for severe
thunderstorms may be on Wednesday afternoon and evening with the
arrival of the front from the northwest. The forecast wind
profiles for that time period suggest that if convection develops
it could become organized. Cape values in excess of 1000 j/kg are
The latest general timing of the main surface low riding along
the frontal boundary brings it across our region on Thursday
night. As is the case with the middle level features, the timing of
the surface wave remains in question. We will keep a chance of
showers and thunderstorms for Thursday into Thursday night, with
mainly a slight chance of showers and thunderstorms for Friday.
Precipitable water values are forecast to rise near or above 2
inches during the middle and late week period. 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 guidance differs with the forecast for next weekend. The main
question concerns whether the frontal boundary will be pushed far
enough south to allow weak high pressure to build into our region
from the northwest and north. As a result, we will continue to
carry either a low or slight chance for precipitation.
Daytime temperatures are anticipated to be within a few degrees
of normal for the period from Monday night through Sunday.
Nighttime temperatures are forecast to be solidly above normal.
Aviation /19z Sunday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
There have been some pesky low clouds that have lingered today
especially at krdg and kmiv. As a result some local MVFR conds have
been occurring in a generally VFR environment. Most taf sites have
been VFR and expect this to continue through the taf period. However,
will bring some low clouds in again overnight at krdg and kabe as
it could be a repeat performance of what happened last night this
morning. There could be some rain showers by the end of the taf period at kabe/krdg
but confidence was not high enough to mention in the individual
A light SW to S flow will continue through the afternoon and Erly evening
before wind becomes very light overnight or almost calm. The wind
will be more southeasterly on Monday with speeds generally 10 knots or less.
Monday night and Tuesday morning...conditions possibly lowering
to MVFR or IFR in low clouds, haze and fog especially during the
late night and early morning hours. A chance of showers and
Tuesday afternoon and Tuesday evening...mainly VFR with a chance
of showers and thunderstorms.
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.
no marine headlines are anticipated through the near and short term
Monday night through Friday...no marine headlines are
a southeast to south wind and swells have resulted in a moderate
risk of the development of dangerous rip currents along the New
Jersey shore this afternoon. There is a low risk at the Delaware