Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
351 PM EST Friday Nov 27 2015
high pressure will weaken across the region tonight. A cold front
will cross the region 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 Saturday morning/...
the surface ridge of high pressure has shifted somewhat south of our forecast area
as it gradually weakens. This has allowed a light southwesterly surface wind to
develop this afternoon. Temperatures are running a couple of degrees higher than
yesterday and are approaching records at some locations. Maximum temperatures might
be a bit higher except for cirrus moving across the area. Deeper
layered clouds associated with a frontal boundary are will to our west
over Ohio/northwest PA/western New York.
For tonight...a cold front will be moving east through PA and is expected
to reach the Poconos and extreme northwest New Jersey by around 12z. This forecast timing
is somewhat slower than yesterday and the flow aloft is somewhat parallel to the
front some it could end up being a bit later than forecast now. Min
temperatures overnight should be a few degrees milder than last night due
to increased high level clouds/moisture and also light SW to west winds
continuing through the night. At this time we do not expect a repeat of the
fog from early this morning. The overnight period should be precipitation-
free except for chance probability of precipitation in the Poconos towards dawn...as the cold
front reaches that area.
Short term /6 am Saturday morning through 6 PM Saturday/...
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 by evening.
Long term /Saturday 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 stalling boundary.
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 /21z Friday through Wednesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy, and surrounding areas.
VFR conds are currently indicated at all our taf sites and should
continue through the evening and overnight. We do not expect a
repeat of the fog from this morning due to high-cloud cover tonight
and warmer temperatures as well as continuing light southwesterly winds.
A cold front will work its way north to S across the area on Saturday.
VFR conds are expected south/ahead of the front but may become MVFR
or eventually IFR north of/behind the front. The front should affect
Abe/ridge Sat morning and points farther south 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
Small Craft Advisory for seas is in place for all coastal waters through 600 PM
Saturday. Seas are above 5 feet at buoy 44009 and are approaching 5 feet
at 44091. Seas are due mainly to a southeasterly swell which is forecast by wave
watch model to increas 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 now.
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.
with the well above normal temperatures we have seen across the
region today, we had a couple of our climate site break their
records! Rers have been sent for both Allentown and reading.
Allentown, PA set a new temperature record while reading, PA tied
the previous record. Mount Pocono, PA and Atlantic City, New Jersey
almost got there but missed by one degree. Georgetown, Delaware also
looks to have missed the record by a couple of degrees.
Here's how things Shook out today (temperature wise)...
Allentown, PA - 62 -1988 and 1959 (previous)
Reading, PA - 65- 2011
65- 2015 (tied)
Mount Pocono, PA - 60- 1984 and 2006
Atlantic City, New Jersey - 69- 1981
Georgetown, Delaware - 71- 1988
Marine...Small Craft Advisory for hazardous seas until 6 PM EST
Saturday for anz450>455.