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658
FXUS61 KPHI 181731
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
131 PM EDT Mon Sep 18 2017

.SYNOPSIS...
Hurricane Jose will continue to track northward and remain well off
the Mid Atlantic coastline over the next couple of days as it
weakens. By Wednesday, it will move slowly northeastward near
southeastern New England through the remainder of the week. High
pressure will also become established to our north through the mid
and late week time period.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
No changes to the tropical storm watches at this time, and
these will be re-evaluated with a 4 PM NHC conference call.

The water vapor imagery shows a ridge into the Northeast
especially New England, however Hurricane Jose continues to
track northward as it parallels well east of the East Coast.
Jose looks to be taking on some non-tropical characteristics
with a dry slot near and east/south of the center as shear is
affecting the system. Meanwhile, high pressure at the surface
is centered near the Canadian Maritimes. The combination of this
high pressure system and the hurricane will continue to result
in a northeast wind today, which will increase some especially
closer to the coast. The water vapor also shows plenty of dry
mid level air, which is also confirmed by the 12z raobs from
Sterling, VA and Upton, NY. Below this layer however continues
to be moisture beneath an inversion. The stratus which has been
beneath an inversion is gradually breaking up at midday given
heating and some dry air entrainment from aloft. This trend
should continue to allow for at least a bit more sunshine to
develop. While a few showers cannot be ruled out, this appears
to be isolated. We do note some instability arriving from the
southeast though.

Temperatures are dependent on the amount of breaks in the
cloud cover. We are warming, although slowly which is reflected
in the latest update, however the lingering cloud cover should
keep it a bit cooler. If enough subsidence and dry air
entrainment can overcome the moist layer, then there will be a
window of opportunity later this afternoon when more sunshine
occurs. The hourly temperature, dew point and wind grids were
adjusted based on the latest observations, then the LAMP
guidance was blended in for a bit.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Tonight, we start to see more influence from Hurricane Jose, both in
terms of increasing winds (along the shore) and increasing chances
for outer rain bands to reach our Coastal Plains. Based on the
current forecast from the National Hurricane Center, it doesn`t look
like we will have many outer rain bands through the overnight hours,
so kept rain amounts generally less than a half of an inch (at least
through the tonight period).

Persistent clouds should limit radiational cooling, so lows are
forecast to range from the upper 50s to mid 60s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Hurricane Jose to have an impact on our weather Tuesday and
Wednesday but still expected to track well offshore. Please
refer to NHC for track and intensity forecasts. Expected impacts
to our region discussed below.

Tuesday through Wednesday night:

Winds: Most of the region will have a windy period Tuesday and
Tuesday night with top wind gusts 20-30 mph inland and 40-45 mph
along the coast. These wind gusts may down a few trees and
wires.

Rainfall: General rainfall of an inch or less is expected with
locally higher amounts on the coast. The 00z RGEM/UKMET and GFS have
come in fairly dry early this morning which gives some pause to the
wetter EC suite and the NAM. Trends of being slightly further
offshore this morning has allowed for the trim back of some
pops and QPF with this forecast update.

Also, clouds will keep temperatures down in the 70`s at least
Tuesday and possibly Wednesday as well. Overnight lows will be
warm, mainly in the 60`s due to the clouds and increased wind.

Thursday through Monday:

Right now about one-third of all ensemble guidance shows Jose making
a loop back to the southwest by the end of the week. A slightly
higher amount of 00z GEFS members are doing this than with
previous runs though. Any southwest movement will depend on the
strength of mid- level ridging developing to our west and north
throughout the remainder of the week. For now, the forecast
will go with the mainstream idea that Jose will continue to be
located east enough of the region to limit impacts besides
coastal flooding past Wednesday.

With the ridging building to our north, mid-level temperatures will
warm even more than we have seen so far allowing highs to make a run
into the 80`s most days with above normal lows as well in the 60`s.
A further east Jose will also allow for ample sunshine. This
forecast went a few degrees warmer than mean ensemble guidance most
days.

If Jose were to trend back to the southwest, it would be much weaker
but bring clouds along with somewhat cooler temperatures.

In conclusion...

Please refer to the NHC for the latest track and advisory and to the
TCV for a more detailed summary of impacts from Jose.

While uncertainty is decreasing on Jose, a westward shift could
still increase the potential impacts our region sees.

Hurricane Maria will have to be watched closely as well but
anything in that regard is still +7 days away.

&&

.AVIATION /17Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

This afternoon...MVFR ceilings should lift some to locally VFR
for a time. A few isolated brief showers cannot be ruled out.
Northeasterly winds 6-10 knots, however 10-15 knots closer to
the coast.

Tonight...MVFR to IFR ceilings. A band of showers should start
to move onshore toward daybreak, however the timing and
coverage is less certain. Some MVFR fog possible late especially
at KRDG. Northeast winds 5-8 knots at KABE and KRDG, and 10-15
knots at the other terminals with the highest winds at KACY.

Tuesday...IFR/MVFR conditions mostly due to ceilings, which may
improve to near VFR for a time in the afternoon especially west
of KACY and KMIV. Some showers are expected to occur, however
the timing and especially coverage is less certain. We only
included showers with restrictions for KACY and KMIV for now
with a VCSH for the I-95 corridor terminals.

Outlook...
Tuesday night: MVFR or IFR possible with showers, particularly
from KPHL to the east. Wind gusts 20-25 knots inland and 30
knots on the coast at times.

Wednesday through Friday: VFR. Northerly or Northwesterly winds
around 10-15 knots Wednesday then decreasing to under 10 knots
for Thursday and Friday.

&&

.MARINE...
Winds and seas will begin building later today in advance of
Hurricane Jose passing offshore. Wind gusts above 25 KT will be
possible by mid afternoon today on the Atlantic Coastal waters.
Winds and seas will continue to build through the overnight
hours with gusts near or above 40 KT and seas above 10 ft
possible by early Tuesday morning.

Outlook...
A tropical storm watch is in effect. Details in the MWW.

Late Monday night through Wednesday...Tropical storm conditions
will be possible. Although winds will begin to diminish Wednesday,
it will take time for seas to subside.

Wednesday night through Friday...Northeast to east swells of 5
feet may continue hazardous seas advisory because of the
meandering and slowly decaying remains of Jose.

Rip Currents...

High surf due to Hurricane Jose will continue to create dangerous
rip current conditions through at least mid week.

&&

.TIDES/COASTAL FLOODING...
A coastal flood advisory has been issued starting this evening.
See the CFW product for more details.

Coastal flooding is expected with the Atlantic coast high tide
cycles tonight through Wednesday due to the passage of
Hurricane Jose. A prolonged period of east to northeast winds
due to Hurricane Jose will force water to build along the
shores. In addition, there is a new moon on Wednesday, September
20th, so astronomical tide levels will be running high.

The high tide cycle of greatest concern at this point is the Tuesday
evening high tide, especially Sandy Hook to Cape May. Otherwise,
mostly widespread minor coastal flooding is expected with the high
tide cycle early Tuesday, and those early Wednesday.

&&

.EQUIPMENT...
KSMQ transmission of data remains out of service.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...High Surf Advisory from 8 PM this evening to 6 PM EDT Tuesday
     for NJZ014-024>026.
     Coastal Flood Advisory from 6 PM this evening to 1 AM EDT
     Wednesday for NJZ012>014-020>027.
     Tropical Storm Watch for NJZ013-014-020-022>027.
     Coastal Flood Advisory from 8 PM this evening to 1 AM EDT
     Wednesday for NJZ016.
DE...High Surf Advisory from 8 PM this evening to 6 PM EDT Tuesday
     for DEZ004.
     Coastal Flood Advisory from 6 PM this evening to 1 AM EDT
     Wednesday for DEZ002>004.
     Tropical Storm Watch for DEZ003-004.
     Coastal Flood Advisory from 8 PM this evening to 1 AM EDT
     Wednesday for DEZ001.
MD...None.
MARINE...Tropical Storm Watch for ANZ431-450>455.
     Small Craft Advisory from midnight tonight to 6 AM EDT
     Wednesday for ANZ430.

&&

$$
Synopsis...Gaines
Near Term...Gorse
Short Term...Johnson
Long Term...Gaines
Aviation...Gaines/Gorse
Marine...Gaines/Johnson
Tides/Coastal Flooding...
Equipment...