Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
1217 am EST Sat Nov 28 2015
high pressure will weaken across the region overnight. A cold
front will cross the region late on Saturday, stalling near or
just south of our area. High pressure will slide across to the
north of the region Sunday night through the early part of the
week. Low pressure developing over the midwestern United States
will push a warm front northward through the region on Tuesday,
followed by a cold front Wednesday. High pressure will then build
across the region for the remainder of the week.
Near term /until 6 am this morning/...
cirrus is forecast to continue building overhead during the night
in the west southwest middle level flow. Middle level clouds are
expected to reach eastern Pennsylvania. Some localized fog is
possible as temperatures drop near the dew point readings in
spots. However, the fog is not anticipated to be nearly as
widespread as it was this morning due to the light southwest to
west surface flow.
Temperatures are expected to drop into the 40s in most of our
forecast area. Any precipitation should off till after daybreak as
depicted on the latest rap and hrrr runs. Any precipitation
chances were removed with the 12:30 am update through sunrise.
Also, temperatures were adjusted in a few spots based on localized
Short term /6 am this morning through 6 PM Sunday/...
the cold front is expected to push southward across the forecast area on
Saturday. However...the slower forecast timing now allows for maximum
temperatures in the 60s generally south of phl...but cooler in the 50s
farther north. This is due to extensive cloud cover behind the
front as well as low- level cold air advection. Again...this could change if the
front is slower than forecast.
We continue to show chance probability of precipitation spreading southward with front on
Saturday. Models still indicate at best weak forcing for upward vertical velocity so
quantitative precipitation forecast amounts are just a few hundredths. The front is expected to
push through the phl area during the afternoon and reach southern New Jersey/northern Delaware
Long term Sunday night through Friday/... a cold front slowly
sags southward through our area Saturday night but looks to get
hung up a bit and may not drop south of the region until late
Sunday or early Monday.
As the front pushes southwards, there will be some chances for
rain. The models are not showing a ton of moisture available with
the front when it moves through but there looks to be enough for
some showers to occur across the region. Southern areas will
likely remain cloudier as a result of remaining closer to the
Temperatures on Saturday night will be much cooler than recent
nights as the air behind the front taps into some of the colder
air seeping down from Canada. Expect a much colder night over the
region as well as temperatures respond to the air entering the
area. One limiting factor may be the amount of cloud cover we
retain, which may allow temperatures to remain a smidgen higher than the
guidance shows. Overall, expect lows to range from the upper 20s
north to the lower 40s across the south.
High pressure will slide across to the north of the region
through the early part of the week. This high should be able to
help push the cold front, at this point a stalling boundary, just
to our south. Areas across the south may continue to see off and
on showers as a result of their proximity to the frontal boundary
but for the most part, we should see some drying conditions for
late Sunday into Monday across our area.
By Tuesday, the surface high pushes off towards the Canadian
Maritimes. Low pressure starts to organize across the northern
plains/upper midwestern states, largely associated with a strong
cut off low in the middle levels. As this system start to push
towards the Great Lakes region, the stalled boundary looks to move
northward as a warm front. This will once again bring showers to
our area. As the system continues to eastward push, a cold front
will move across the area on Wednesday.
With the warm front moving through on Tuesday, we should see some
warming occur as warm air advection takes place. Temperatures will
rise into the 50s again for Tuesday and Wednesday, with the
potential for some 60s, as we start to tap into the warm moist air
emanating from the Gulf region.
The cold front looks to arrive sometime on Wednesday. Showers are
expected to accompany the front and once it moves through, high
pressure returns and we should clear out with a return to some
cooler and more seasonable temperatures across the region.
Aviation /05z Saturday through Wednesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy, and surrounding areas.
VFR conditions are expected for overnight with cirrus and
eventually some middle level clouds building overhead. Localized fog
is possible. However, the fog should not be nearly as widespread
as it was this morning. We have indicated a visibility
restriction at kmiv before daybreak on Saturday.
Conditions are forecast to favor VFR on Saturday with ceilings
lowering gradually. We have indicated a transition to MVFR
ceilings at krdg and kabe during the afternoon with the arrival of
of some scattered showers. This timing is a few hours later for
kphl, kttn and taf sites further southeast. IFR conditions are
even possibile from middle evening on, low probability at this time to
include with 06z tafs.
A light southwest to west wind tonight will become light and
variable in spots. The wind should be light and from the west on
Saturday morning, veering toward the northwest in the afternoon.
Saturday night...mainly VFR conditions expected. Scattered
showers as a cold front moves through with MVFR conditions
possible. Northerly winds around 5 to 10 knots.
Sunday through Monday...mainly VFR conditions expected. A chance
for showers and sub-VFR conditions, mainly across the southern
terminals. Northerly winds becoming more easterly throughout
Monday. Winds will generally be 5 to 10 knots but some gusts up to
20 knots are possible, mainly towards the coast.
Tuesday...MVFR conditions, with IFR or lower possible, in
widespread rain. East to southeast winds around 10 knots or less.
Wednesday...improving conditions to VFR from northwest to
southeast behind a cold frontal passage. Southwest winds will turn
to the west as the front moves through. Winds around 10 knots with
gust up to 20 knots possible.
Small Craft Advisory for seas is in place for all coastal waters through 600 PM
Saturday. Seas are due mainly to a southeasterly swell which is forecast by
wave watch model to increase somewhat further. So Small Craft Advisory will be left
as is although it may turn out to be marginal for our northern
waters. The ending time late Sat afternoon still looks reasonable for
Saturday night...seas may be near 5 feet as we head into Saturday
night but they are expected to subside through the night. A Small
Craft Advisory may be needed for a brief period Saturday night.
Sunday...sub-advisory conditions are expected.
Sunday night through Tuesday...seas will increase across the area
waters as we see an increasing easterly flow develop. Seas should
start to subside starting Monday but especially the southern
waters may take longer to drop, remaining elevated through late
Tuesday. Winds may gust around 25 knots on Monday with a
tightening pressure gradient taking place.
Wednesday...winds will turn more to the south and then to the
west with both seas and winds expected to increase. A Small Craft
Advisory may be needed.
a new record high temperature was recorded at Allentown yesterday and
the record was tied at reading. Record event reports were issued
for both locations.
Allentown PA - 65 - yesterday
62 - previous record set in 1959 and
Reading PA - 65 - yesterday
65 - previous record set in 2011
kdix radar is currently inoperable. Technicians have been notified about the out
age. The return to service time is unknown at this time.
Marine...Small Craft Advisory for hazardous seas until 6 PM EST this
evening for anz450>455.