Scientific Forecaster Discussion
fxus61 kphi 231414
Area forecast discussion
National Weather Service Mount Holly New Jersey
1014 am EDT Sat Sep 23 2017
the remnant low of Jose, currently southeast of Nantucket
Island, will continue to weaken and drift offshore through the
weekend. Meanwhile, high pressure remains entrenched over the
northeast before moving offshore by the middle of the week.
Hurricane Maria will track northward over the Atlantic waters,
approaching the mid-Atlantic coast on Wednesday, then curving
out to sea on Thursday as a cold front passes through the
region. High pressure builds east to close out the week.
Near term /until 6 PM this evening/...
no changes needed to the ongoing fcst.
The impressively resilient Jose will continue its slow decay
southeast of Cape Cod today as a 590+ dam 500-mb ridge continues
to build in the Great Lakes region. Meanwhile, Hurricane Maria
will continue to be drawn northward toward the weakness in the
ridge provided by Jose. More on Maria in the long-term
discussion. In the near term, the midlevel ridging will be our
region's dominant player, as Jose will remain well away from the
coast. Subsidence downstream of the ridge will generate a
nearly cloud-free sky by afternoon, and a northerly to
northwesterly surface flow will provide sufficient mixing and
downsloping (combined with a notable lack of cold-air advection)
to warm temperatures a few degrees more from those seen Friday.
The near-surface drying will prevent apparent temperatures/heat
indices from separating much from ambient temperatures, which
are forecast to reach the 80s across the area (mid to
potentially upper 80s in the urban corridor; around 80 in the
southern Poconos and along the immediate coast).
The surface pressure gradient will diminish somewhat today as
Jose drifts a bit more offshore. As such, there is a good chance
for the sea breeze to move inland a bit this afternoon.
Short term /6 PM this evening through 6 am Sunday/...
as Jose drifts a bit more offshore tonight, the surface ridge
to our west will edge eastward into our region. This will allow
winds to relax after dark. Meanwhile, surface dew points will be
a few degrees higher than the previous night (perhaps aided to
some degree by progression of a vort Max across eastern Canada,
with subtle moist-air advection occurring southeastward around
the Great Lakes/Appalachians ridge). As temperatures nocturnally
decline, surface decoupling should allow a bit more patchy fog
to develop than that seen Friday night. Have included mention in
the grids for the particularly susceptible valley locations
northwest of the fall line and in The Pine Barrens of New
Temperatures should be a few degrees warmer than those observed
Friday night as well, generally around 60 in the southern
Poconos to around 70 in the Philadelphia metropolitan area --
well above average for this time of year.
Long term /Sunday through Friday/...
surface high pressure will be firmly entrenched over the region
on Sunday before lifting to the north and east on Monday. Sunny
skies with very warm temperatures will be in place with highs
topping off in the upper 80s to low 90s on Sunday, and then
slightly cooler on Monday as a northeast flow takes place. This
will usher slightly cooler temperatures across the region,
especially for right along the coast, where highs will be in the
upper 70s to around 80.
During this time, Hurricane Maria will lift to the north over
the western Atlantic waters. Latest model runs, and the
ensembles reflect this as well, show Maria taking a bit more of
a western track, possibly approaching the East Coast of North
Carolina Tuesday into Wednesday. Outer rain bands associated
with Maria will lift to the north, and spreading from east to
west into the region during this time. Please see the forecast
discussion from the National Hurricane Center for the latest
information on the track and forecast.
A cold front moves across the region Wednesday, followed by
another cold front on Thursday. High pressure returns on Friday.
During this time, showers and possible thunderstorms will
develop with the passage of each cold front. Temperatures drop
off to the upper 70s to low 80s Wednesday and Thursday, and then
much cooler weather returns for Friday with highs in the low
The week starts off with temperatures well above normal, then
closes with temperatures below normal.
Aviation /14z Saturday through Wednesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
VFR through tonight. Light/variable winds will become northerly
around or below 10 kts during the day. Very few clouds are
expected by late morning. Patchy fog may occur in more
susceptible valley locations tonight (i.E., Krdg, kabe, and
kmiv), but confidence is too low and occurrence too transient
for mention in the tafs at this time.
Sunday through Monday...VFR conditions with NE winds less than
Tuesday through Wednesday...mainly VFR conditions expected, but
there may be some showers each day. NE winds as high as 10-15
Small Craft Advisory for hazardous seas remains in effect for
the Atlantic coastal waters, though conditions may become
marginal (i.E., Seas may subside slightly below 5 feet for a
time), especially for the northern/central New Jersey coastal
marine zones, this afternoon and tonight. Winds should remain
below advisory criteria through tonight, though northerly
breezes may gust 15-20 kts during the day. Winds may become more
variable late this afternoon into this evening before re-
establishing a primarily northerly direction tonight. Long-
period easterly swells should continue through tonight, with
components both from Maria (southeast) and the remains of Jose
(northeast) potentially generating some undesirably choppy
Sunday through Wednesday...elevated seas due to swells
associated Hurricane Maria will impact the waters during this
time. Seas 4-6 feet Sunday will gradually build to 8-12 feet
Tuesday and Wednesday. NE winds will range from 10-15 kt,
increasing to 15-20 knots with gusts up to 25 knots for the ocean
Swells from the remains of Jose will continue today (generally
4 to 6 feet from the northeast with a period of 9-10 seconds),
but with time, swells from Maria will become a bigger player
(generally 2-3 feet from the southeast with a period of 13-16
seconds). For today, this could create rather chaotic surf.
Though swell heights will likely be lower than seen recently,
the combined effects of Jose and Maria will maintain at least a
moderate risk of dangerous rip currents today. If entering the
surf zone, be especially cautious today. Only swim in the
presence of lifeguards/beach patrols, and heed the advice of
A prolonged period of moderate to high risk for the development
of dangerous and life threatening rip currents is on tap for
most of the upcoming week due to swells emanating from Hurricane
spotty minor flooding may occur with this morning's high tide
thanks to the continued influence from Jose, but any flooding is
not expected to be widespread enough or severe enough for
issuance of an advisory. Forecasts for this evening's high tide
are even lower.
with high temperatures making a run at 90 Sunday and Monday
across the region, some record high temperatures may be tied or
broken. The highest chances are on Monday where all locations
but Georgetown are expected to be within three degrees of a
Here are the records for both days.
Ged-92(2010 and 1970)
Marine...Small Craft Advisory for hazardous seas until 6 am EDT Sunday