Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
128 PM EDT Thursday Oct 30 2014
high pressure will build over our region today. By tomorrow, a low
will begin to dig southeast from the Great Lakes region. At the same
time, an off shore low will lift northeast. By Saturday night, the
two lows will merge off shore resulting in cool and unsettled
weather for our region. High pressure will then build in early next
Near term /until 6 PM this evening/...
fog has burned out this morning. Drier air will continue to
filter across the area over the next few hours. With the 9:30 am
update we slightly adjusted some of the temperatures due to
morning for or the lack thereof. Remainder of forecast looks on
track. Still think 60 is a reasonable expectation at phl given
quick response in temperatures this morning.
Today should end up being a pretty nice day as high pressure
builds to our west and tries to push into our western areas. A
short wave/vorticity maximum will move through the area this morning,
although no precipitation is expected across our area as any precipitation to
the northwest should dissipate before it gets here. Some stratocu
will move down across the area from the northwest and have raised
sky cover northwest of phl for this. A patchy area of clouds will impact
southeast New Jersey here over the next few hours as well.
Highs today were a blend of mav/met MOS and blended European model (ecmwf) 925mb
temperatures which keeps everyone pretty close to normal.
Short term /6 PM this evening through 6 am Friday/...
high pressure will dissipate as it moves into our area overnight,
although we are still expecting a quiet night. Any clouds from the
day should dissipate after sunset and mostly clear skies are
expected early in the night, before a return of some clouds
overnight. Overnight lows were a blend of mav/met MOS which keeps
everyone pretty close to normal.
Long term /Friday through Wednesday/...
the biggest story through the long term will be the low that digs
southeast from the Great Lakes region Friday, sliding off the Carolina
coast Saturday and merging with an off shore low.
Friday and Friday night...though we will technically still be in
the warm sector of the system, it won't feel much like it. Thanks
to the off shore surface low, onshore flow is expected to develop
rather early in the day Friday leading to cool and cloudy weather.
Expect most location to see highs in the 50s, with the exception
of the higher terrain of the Poconos it likely won't get out of
the 40s. Precipitation associated with the Continental low could begin
to move into the Poconos from the west as early as Friday
afternoon. Meanwhile, the onshore flow could result in light
precipitation along the coast. By Friday night, expect the onshore, and
upslope flow to result in light precipitation further inland.
Saturday and Saturday night...the now occluded cold front will
move through on Saturday, bringing slightly cooler conditions. One
interesting thing to watch will be how quickly the drier air moves
in. If the middle and upper levels dry out as quickly as the GFS is
suggesting, snow seems very unlikely as by late Saturday evening,
only the boundary layer will be nearly saturated. This would
suggest more of a drizzle/freezing drizzle event. However, the
European model (ecmwf) and NAM still show some chance of seeder feeder clouds
through at least 09z, which could lead to a brief period of snow
for the Poconos and Lehigh Valley. Even if precipitation does change
over, precipitation amounts are expected to be very light.
Sunday night...as skies clear and winds begin to decrease, this
will set the stage for prime radiational cooling conditions. As a
result...expect much of the region to see lows near or below
freezing, including the 15 remaining counties (primarily in
Delmarva, the urban corridor, and far southern nj) that have not
yet had a hard freeze.
Monday through Tuesday...a broad high amplitude ridge begins to
build east. Expect modest warming each day thanks both to air mass
modification ad increasing 1000-500mb thicknesses.
Wednesday and Thursday...could see an upper level trough and
associated cold front move through the region during this time.
However both the GFS and European model (ecmwf) are disagree about timing and track
of this feature. Thus, have stayed close to the previous forecast.
Aviation /18z Thursday through Tuesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
Cloud cover is moving across the area from the northwest with
bases around 3,500-5,000 feet, and should vary from broken to
scattered from northwest to southeast. This cloud cover will dissipate
after sunset. With a drier airmass moving in, no fog is expected
Winds will be from the north/northwest at 5-10 knots this
afternoon then become light and variable overnight.
Another VFR day is expected Friday with an increase in middle-level
clouds around 4,000 feet in the afternoon. Expect any MVFR ceilings
to hold off until Friday night in advance of the next rain maker.
Friday night: -shra could move in by Friday night resulting in
occasional MVFR visibilities.
Saturday...IFR ceilings are possible by Saturday morning. Breezy
northerly winds possible.
Saturday night...conditions will slowly improve from west to east
through the night. Breezy northwest winds may continue especially at Acy.
Sunday and Monday...mostly VFR conditions.
sub-Small Craft Advisory conditions are expected across the waters
through tonight as high pressure noses it's way across the area from
Friday...winds and seas should remain below Small Craft Advisory criteria.
Friday night through Sunday...winds will build into Small Craft Advisory criteria,
and then gales, with peak gusts near 40kt possible during the day
on Saturday. Gale conditions could continue through much of the day
Sunday night into Monday...winds will stay in Small Craft Advisory criteria through
an onshore component of the breezy to windy conditions on Saturday
will lead to elevated water levels this weekend. Minor tidal
flooding may occur with the high tide cycles Saturday and Saturday