Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 160130
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
930 PM EDT Fri Sep 15 2017

.SYNOPSIS...
A surface trough will weaken tonight. High pressure will gradually
build to our north and then northeast through this weekend. Tropical
cyclone Jose is forecast to move northward and intensify off the mid-
Atlantic coast through early next week. Mariners are urged to keep
informed on the latest National Hurricane Center forecast.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Tropical wording will in the zone and coastal waters forecast
until the tropical probabilities decrease below our NWS - NHC
standardized mentionable thresholds.

Skies will continue to clear out tonight. With LGT/VRB to
nearly calm winds, there should be good radiational cooling
conditions away from the urban areas. Patchy dense fog, albeit
shallow, but effective, develops in the countryside later on.
Lows generally 5 to 10 degrees above normal.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
There remains a chance of mainly afternoon showers as a weak
trough aloft and associated vorticity should linger. Most of the
lift and showers should be in the hills north of I-78.

Otherwise, we`re looking at a very nice day with plenty of
sunshine but the standard summer diurnally driven afternoon cu
fields. Temps might 2-3F warmer than they were today-Friday the
15th. Light wind probably trending east or south.

This forecast was again a general 50 50 blend of the 12z/15
GFS/NAM MOS. which forecasts max temps generally 4 to 9 degs
above normal, depending on location.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Synoptic overview...The period starts with a mid-level ridge
dominating much of the eastern half of the U.S., and for the most
part, ends that way as well. The exception, will be Jose as it works
up the eastern seaboard, goes extra-topical, and gets absorbed into
the westerlies.

At the surface, a weak trough will persist through the weekend
across the northeast and the Mid-Atlantic. On Monday, we`ll see a
cold front tracking through the Great Lakes and per the official TPC
forecast, Jose moving off the Carolina coast. On Tuesday, the cold
front to our west begins to weaken as Jose moves northward, east of
Virginia. On Wednesday, again using the TPC forecast, Jose weakens
to a TS off the DE/NJ coast. The TPC track has it about 200 miles
off the DE/NJ coasts with the west side of the cone on the NJ coast.
Jose pulls away on Thursday as surface high pressure begins to move
into the region from the west. Surface high pressure, under the
aforementioned mid-level ridge will be featured on Friday.

Temperatures...For comparison, normals at PHL are around 60 and in
the upper 70s. Expect above normal temps on Sunday, both highs and
lows. For Monday, expect above normal lows and near normal highs.
For Tuesday, above normal lows and below normal highs. For Wednesday
and Thursday, above normal lows and near normal highs. For Friday
near normal lows and highs.

Precipitation...Small POPS (chance) have been painted for Saturday
evening, north and west of the I95 corridor. Small POPS (slight
chance/ chance) are in the grids for Sunday across the I95 corridor
and points north and west. Small POPS (slight chance/chance) are in
the grids for Sunday night and Monday across the coastal plain.
Increasing POPS remain in the grids for Monday night across much of
the CWA, especially across the coastal plain. Highest POPS will be
on Tuesday with likelies on the coast. Decreasing chance POPS on
Wednesday. No POPS Thursday and Thursday night. Small POPS (slight
chance/chance) once again on Friday. The WPC 5-day has 0.50 to 0.75
along the coast.

Winds...Benign east to northeast winds are currently expected
Saturday night through Sunday night. Increasing northeast winds
along the coast on Monday peaking on Tuesday...gusts up to 35 mph.
Slackening northwest winds on Wednesday. Benign winds once again
Thursday and Friday.

Impacts...Follow the official TPC track for Jose. Keep in mind,
there are 4 daily updates at a minimum. Attm, as Jose passes the
DE/NJ coasts, it will be about 200 miles offshore. Also, keep in
mind that when a system loses its pure tropical characteristics,
winds spread out. TPC puts about a 20 to 30% chance of tropical
storm force winds across our waters. TS winds are defined as 39 to
73 mph.

Rain and wind, are currently expected to commence late Monday
night/early Tuesday and persist through early Wednesday. An increase
in winds can also be expected during this time as well. Of course,
depending on how close Jose passes to the coast will determine how
strong these effects area. Coastal areas of Delaware and New Jersey
have the greatest chance of seeing any impacts.

Swells from Jose will arrive tomorrow, increase on Sunday, and peak
Monday into Tuesday. This will increase the rip current threat. Some
minor beach erosion and coastal flooding is possible.

Please stay tuned to the National Hurricane Center for the latest
official track and forecast regarding Tropical Storm Jose. Remember,
we are at the peak of hurricane season for the Atlantic Basin, so it
is important to have a hurricane plan in place. For tips as to what
to have in your hurricane plan, please check
http:/www.nws.noaa.gov/om/hurricane/plan.shtml

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...VFR with PATCHY IFR conds in st/fog late at night in
the countryside. METMOS vsbys look potentially as better
indicators of the fog vsby than the GFS. Nearly calm wind.

Saturday...VFR sct-bkn developing aoa 5000 ft during the afternoon.
Small chc of a mid or late afternoon showers vcnty KRDG/KABE
but not in the TAF due to low probability of occurrence. Light
wind.

OUTLOOK...

Saturday-Sunday night...Mainly VFR. Best chance of MVFR north and
west covering KABE/KRDG, Patchy fog/stratus during the late
night/early morning hours. Scattered showers also possible during
the afternoon and evening.

Monday-Tuesday...An increase in MVFR possible as Jose approaches the
area. Rainfall chances will increase later Monday and persist
through Tuesday night. Depending on the track of Jose, winds could
increase across the area as well with KACY being the terminal with
the greatest chance.

Wednesday...Becoming VFR with decreasing northwest winds.

&&

.MARINE...
Winds and seas should stay below small craft advisory criteria
through most of Saturday. SCA seas may develop late Saturday
afternoon in our s NJ and De Atlantic waters when swells from
Jose are expected to arrive. At this time, due to a sometimes
bias of swells arriving too soon, we`ve reserved this long
period Hazardous SEAS SCA for Saturday night.

Outlook...

Saturday night...long period swells expected building to 5 or 6 feet.

Sunday and Sunday night...long period swells expected building to 5
to 7 feet.

Monday and Monday night...Winds are forecast to increase through the
day and into the night with gusts of 25-35 knots possible. Seas will
continue to increase to 6 to 10 feet.

Tuesday...Depending on the track of Jose, winds could continue to
increase...gusts to 40 knots. Seas could increase to 10-15 feet.

Wednesday...Winds and seas subsiding. Northwest winds 10 to 15
knots. Seas subsiding to 4 to 6 feet.

Rip Currents...

For the remainder of today, we are forecasting a moderate risk
for the formation of dangerous rip currents. Long period (10-12
second) southeasterly swells.

Saturday: A moderate risk for the formation of dangerous rip
currents is expected to redevelop by afternoon as swells build
a foot or two from the values of this Friday afternoon.

High risk for the formation of dangerous rip currents is
expected Sunday through at least Tuesday (17th through at least
the 19th) as long period and larger swells from Jose become more
pronounced along our shores, especially as it passes to our
east on Tuesday into Wednesday (per the track cone of
uncertainty as posted by the National Hurricane Center).

&&

.TIDES/COASTAL FLOODING...
Coastal flooding is possible starting with the high tide cycles
on Monday and continuing through Wednesday with the approach
and passage of what is currently Tropical Storm Jose on Tuesday.

A prolonged period of east to northeast winds will allow water
to pile up along the shores. In addition, there is a new moon on
Wednesday, September 20, so astronomical tide levels will be
running high. In some cases, minor coastal flooding thresholds
could be met without the influence of Jose.

Depending on how close Jose tracks to the coast changes how
significant the coastal flooding will be. Based on the latest
guidance, we can expect minor coastal flooding to begin with the
high tide cycle possibly as early as Sunday evening in
Delaware, but not until Monday evening in northern New Jersey.
There is then the potential for moderate coastal flooding with
the passage of Jose on Tuesday and Wednesday. If Jose tracks
closer than the current forecast indicates, there could be
moderate to major coastal flooding in some areas.

&&

.EQUIPMENT...
The Somerville (SMQ) observation remains unavailable due to a
web issue.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory for hazardous seas from 6 PM Saturday to
     6 AM EDT Sunday for ANZ452>455.
     Small Craft Advisory for hazardous seas from midnight Saturday
     night to 6 AM EDT Sunday for ANZ450-451.

&&

$$
Synopsis...Kruzdlo
Near Term...Drag/MPS
Short Term...Drag
Long Term...Kruzdlo
Aviation...Drag/Kruzdlo/MPS
Marine...Drag/Kruzdlo/MPS
Tides/Coastal Flooding...MPS
Equipment...MPS



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