Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
346 am EDT Monday Sep 22 2014
in the wake of the cold front that moved through last night, a high
will build in over the region to start the week. By Thursday, a low
will lift northeast just off shore. Another high will build in
right behind that and remain the dominant feature through the end
of the week.
Near term /until 6 PM this evening/...
an area of low pressure that pulled a cold front across the area
overnight will continue to lift into eastern Canada today, while
high pressure across the central part of the country starts to nose
into our area from the west. This will create gusty northwest winds
across the area for much of the day today. Drier air will filter in
across the area, especially as a secondary trough slides across the
area later during the day. With precipitable water values below half an inch, no
precipitation is expected. There will be some cloud cover as the
stratocu to our northwest filters across the area in the northwest
flow. Temperatures today were a blend of mixed 925 mb European model (ecmwf) temps,
mav/met MOS, and mosguide. Overall, highs today are expected to be a
couple of degrees below normal, although it may feel slightly cooler
with the breezy conditions and lowering dewpoints.
Short term /6 PM this evening through 6 am Tuesday/...
high pressure will continue to push into the area overnight. Skies
will begin to clear out after sunset, and wind gusts will diminish
as well. Light winds and mostly clear skies will lead to good
radiational cooling. Overnight lows were a blend of mav/met MOS and
mosguide, which brings everyone a few degrees below normal.
Temperatures are expected to drop into the upper 30s across the
Poconos, but we still think most areas should be warm enough to
prevent frost from forming, although a few isolated spots of frost
would not be surprising.
Long term /Tuesday through Sunday/...
Tuesday into Wednesday...the surface high will slowly slide
propagate northeast away from the region. In the upper levels, the
main upper level trough will also be lifting NE towards the North
Atlantic. As a result expect increasing thicknesses. Thus, could
see a modest warming trend through this period from temperatures
slightly below normal on Tuesday to near normal for Wednesday.
Wednesday night into Thursday night...as the upper level trough moves
off over the next few day, a cutoff low is expected on the
southern end of the trough and then drift southeast over the Carolinas
through middle week. This looks to be the start of the off shore
system that could affect our coastal waters and far eastern zones
through this period. Models are still in poor agreement on the
track of this low, and model agreement may not improve much until
the cutoff low develops. At this point, expect any impacts,
limited at that, to be confined to Delaware-Maryland-Virginia and southern and
eastern New Jersey. Kept probability of precipitation in this area limited to slight chance
mention withe the track uncertainty.
Friday and beyond...another high builds over the region by
Friday. The associated upper level ridge is unusually high
amplitude for this time of year, as the center of the high both at
the surface and in the upper levels could be north of the region.
Thus, expect the region to be under easterly flow which could
slightly temper the warming trend through this period, but should
still see temperatures around 5 degrees above normal by Saturday.
The next thing to watch will come at the very end of the period as
the GFS and European model (ecmwf) show an upper level trough digging out of
central Canada into the Great Lakes region towards the end of the
period. There is still considerable uncertainty with the track and
uncertainty of this system.
Aviation /07z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
We expect conditions to be VFR through the taf period, although we
expect cloud cover to increase this morning through sunrise as
clouds filter down across the area from the northwest in the
northwest flow. Ceilings are expected to be in the lower end of the VFR
range, around 3,000-4,000 feet. Cloud cover will begin dissipating
later today into this evening, and mostly clear skies expected
Winds that have not begun gusting yet will begin in the next couple
of hours through sunrise and continue to be gusty through today.
Wind gusts will begin to diminish later this afternoon/evening and
will lighten as high pressure builds into the area tonight, although
there should still be a light breeze overnight.
Tuesday and Wednesday...VFR conditions expected.
Thursday...mostly VFR conditions expected. There is a small risk
of ceilings into the MVFR range and MVFR visibilities with br and
-ra closer to the shore including kacy and kmiv.
Friday...VFR conditions expected.
winds are beginning to increase and should gust around 25 knots for
a good part of the day. Seas are expected to build now the winds are
increasing, and could build to 5 feet. Therefore the Small Craft
Advisory remains across the Atlantic Ocean and lower Delaware Bay.
We ended up extending the advisory a few hours into the afternoon as
winds and seas may remain elevated.
Winds and seas are expected to diminish later this afternoon into
this evening as high pressure continues to build across the area.
Tuesday...winds and seas are expected to be below Small Craft Advisory criteria.
Wednesday and Thursday...winds and seas will likely increase by
middle day Wednesday to Small Craft Advisory criteria. At this point, expect winds to
gust near or just above 25kt, especially for the coastal zones
adjacent to Delaware and southern New Jersey. Expect waves to generally remain
in the 5 to 6 foot range through this period. However, there is some
uncertainty on the track of this system, and wavewatch guidance
shows wave heights up to 9 feet through this period, but this seems
unlikely as the pattern doesn't appear that conducive for such
large waves and it is currently running a bit high.
Friday...waves should fall back below Small Craft Advisory criteria early in the
local guidance indicates that there will be a moderate risk of rip
currents today into tonight.
Marine...Small Craft Advisory until 5 PM EDT this afternoon for anz431-