Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
000
FXUS61 KPHI 210137
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
937 PM EDT FRI MAY 20 2016

.SYNOPSIS...
High pressure shifts off the mid Atlantic coast overnight, giving
way to developing low pressure off the VA Capes late Saturday,
which will progress northeastward well offshore Sunday morning.
High pressure over the Mississippi Valley Monday slowly moves east
and will cross our region by mid week. Low pressure moving through
the Great Lakes Thursday is expected to lead to a cold frontal
passage across our area Friday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Clouds will continue to overspread the region this evening and
overnight. The leading edge of the rain is forecast to arrive
across our southwestern zones right around daybreak. Overnight
lows will drop into the mid 40s and mid 50s which is pretty much
where we should be for this date. Overall, winds will be light out
of the southeast.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
The rain will push across the CWA from southwest to northeast
tomorrow morning. By midday, just about everyone will have the
opportunity to get wet. By midday, the coastal surface low will be
developing well off the Virginia Capes and will push northeast out
to sea the remainder of the afternoon.

QPF amounts have increased the last 12 hours. Through the day
tomorrow, the area could pick up as much as a 0.25 inch well north
and west to between 1.00 and 1.50 across extreme southern NJ and
across the Delmarva. With the rain forecast to be heavy at times,
some poor drainage and nuisance flooding is possible.

Temps will climb into the upper 50s to mid 60s. Winds will begin to
pick up out of the east tomorrow morning across southern NJ and
southern DE. The winds will back to the NE in the afternoon and
could gust into the 25 to 30 mph range across the coastal plain.
Strongest winds will be along the southern beaches.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
A Mid level trough will close off over the northeastern quarter of
the U.S. and become our dominant weather maker in the Sunday thru
Tuesday time frame. Brief ridging will follow in the wake of this
feature Wed, after which the northern stream lifts well north into
Canada, promoting a southwest flow aloft. Several southern stream
shortwaves will eject out of a mean trough over the southwest US and
affect our weather thru the end of the work week. Temperatures will
be below normal thru Monday under the influence of the upper low,
then trend above normal after Tue, as mid level heights rise.

Saturday Night...Surface low is progged just southeast of the mouth
of DE Bay around 00Z Sun, and will be progressive, moving northeast
further offshore overnight. The heavier rainfall should be exiting
the region by midnight, with some lingering scattered showers in the
wake of the system.

Sunday...Mid-level trough cuts off overhead, with cold air aloft,
and ample moisture in the column. Expect considerable cloudiness,
with scattered showers in the afternoon. Cannot rule out a rumble of
thunder, and SPC does have points northwest of I-95 in general
thunderstorms. While it`s cold aloft (-19C at 500 hPa), and there
will be a weak surface trough setting up over the aforementioned
area, mid-level lapse rates are weak and instability is meager.
At this time, expect some low topped showers.

Monday and Tuesday...The cutoff low is progged over Delmarva Mon and
is anticipated to begin moving northeast toward Southern New England
Tue. Ground fog is a possibility Mon morning given the weak gradient
and abundant low-level moisture, but will be dependent on how much
clearing takes place during the overnight. For now, have inserted
patchy fog into the forecast. Otherwise, expect similar weather Mon
and Tue compared to Sun. In addition to showers, there will be a
better chance of isolated pulse-type convection both days, given
better modeled instability. However, uncertainty regarding spatial
extent leads to low confidence, so it`s not reflected in the current
forecast.

Overall, we have kept consistency with the previous forecast of the
last few days, with at least some pops during the Sun thru Tue time
frame. Due uncertainty regarding spatial extent, later shifts can
adjust accordingly.

Wednesday...Weatherwise, the pick of the week at this time. The mid
level ridge crests over the region as surface high pressure moves
offshore. Sunny skies to start with high clouds streaming in aloft
as the day progresses. The flow will become southwest with
temperatures rebounding to several degrees above normal. The
gradient should be weak enough for a sea breeze to develop along the
coast and DE Bay, which will allow for cooler temps.

Thursday and Friday...Low pressure moving through the upper
peninsula of Michigan will promote a pre-frontal trough Thu
afternoon and a gradual cold frontal passage during the day Fri. The
best chance for convection will be Thu, and possibly Fri, depending
on the timing of the fropa. The models indicate sufficient moisture
and instability, but with the upper jet displaced to the north,
shear is lacking for more organized convection. Both days, 850 hPa
temperatures approach 30C, so depending on the extent of mixing,
high temperatures have the potential to reach well into the mid
80s along the I-95 corridor.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

Overnight...VFR with light southeast winds becoming east toward
daybreak.

Saturday...VFR at sunrise will transition to MVFR and than to IFR
around midday. LIFR is possible during the afternoon hours. NE winds
will gust between 20-25 kt during the afternoon from the I95
terminals eastward.

OUTLOOK...
Sat night...Widespread MVFR, particularly I-95 terminals and
points southeast, with IFR possible at ACY in MIV, mainly in low
clouds and SHRA. Northeast winds could gust 20 to 25 knots early
in the night I-95 terminals and points southeast, particularly
ACY.

Sun through Tue...Predominantly VFR, with a low probability of a
short period of MVFR in widely scattered SHRA each afternoon.

Wed...VFR.

&&

.MARINE...
Quiet conditions on the water overnight, then things go downhill
tomorrow with the coastal low tracking just east of our waters.
Forecast soundings did not support a Gale Warning, so SCA`s were
issued. They begin late morning. For the ocean, I have them going
through Saturday night. For Delaware Bay, they`re up through the
evening hours. Winds will gust from the east and seas will build
to 4 to 6 ft on the ocean.

OUTLOOK...
Sat Night and Sun...SCA is in effect for DE Bay thru 02Z Sun and
the Atlantic Waters thru 10Z Sun. The SCA may need to be extended
for hazardous seas over the Atlantic waters into the day Sunday.

Sun night thru Wed...Both winds and seas are expected to remain
below SCA criteria.

RIP CURRENTS: The Surf Zone Forecast began for the season Fri
morning.

The Surf Zone Forecast currently has a news headline on our
homepage. It should also be accompanied by a probable debut of the
Experimental National Beach Forecast page (if not Saturday morning,
then certainly early next week). You will be able to click the beach
located umbrella and comprehensive beach localized forecast
information including beach specific forecasts, the surf zone
forecast, ultraviolet index, rip current preparedness/safety
information for beaches within our forecast area. DIX and DOX live
radar will be posted on the right side as well as a Rip Current
recognition video, and Lightning Safety tips. Comments on the page
will be welcome.

We expect that we will need to adjust the density of the beaches
offered.

All this was tied together in a social media announcement Friday
afternoon.

Ultimately for beach goers maximum enjoyment and safety...swimming
within vision of lifeguards is a best practice.  Rip currents come
and go, tending to repeat only near jetties and piers, particularly
the incident side of the swell. Rip currents may be a little
stronger when the tide cycle is in the lower half of its cycle. Most
rip current fatalities are male, under 40 and unguarded beaches.

Water temperatures are currently a little below normal, mid 50s.

&&

.TIDES/COASTAL FLOODING...
At this time, all available guidance indicates water levels for both
the Saturday evening and Sunday evening high tides will remain below
the threshold for minor flooding.

&&

.CLIMATE...
As we near the conclusion of the 2016 meteorological spring,
preliminary estimates indicate ABE on pace for a top ten driest,
barring significant rainfall over the next 12 days. The average
spring rainfall for ABE is 11.09 inches, with 5.58 inches as of
5/19. If less than 1.89 inches of rain falls for the remainder of
May, ABE will be at least within the top ten.

In terms of the May 2016 monthly climate (as of 5/19), all of the
big four long term climate sites have experienced temperatures below
normal and precipitation above normal. The following table lists:
the normal average vs. May 2015 average and the resultant departure
from normal for both temp and precip.

SITE    TEMPERATURE (F)       PRECIPITATION (IN)
----    ------------------    ---------------------
ACY     59.3 VS. 55.7 -3.6    1.96  VS  3.93  +1.97
PHL     62.1 VS. 57.8 -4.3    2.20  VS  2.96  +0.76
ILG     60.9 VS. 56.4 -4.5    2.35  VS  3.10  +0.75
ABE     58.0 VS. 55.2 -2.8    2.44  VS  2.83  +0.39

note: the above normals represent the month through May 19.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 11 AM Saturday to 6 AM EDT Sunday
     for ANZ450>455.
     Small Craft Advisory from 11 AM to 10 PM EDT Saturday for
     ANZ430-431.

&&

$$
Synopsis...Franck
Near Term...JK
Short Term...Kruzdlo
Long Term...Franck
Aviation...Franck/Kruzdlo
Marine...Franck/Kruzdlo
Tides/Coastal Flooding...
Climate...



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.