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 46 47 48 49 50
000
FXUS61 KPHI 300803
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
403 AM EDT Tue May 30 2017

.SYNOPSIS...
A stationary front remains along the Mid-Atlantic through the
middle of the week. Low pressure develops along the boundary and
passes off the Mid-Atlantic coast on Tuesday, followed by
another area of low pressure passing south of the area on
Wednesday. A cold front crosses the region Wednesday night. High
pressure passes through the area Thursday through Friday,
followed by a series of low pressure systems that will impact
the area through next weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Another cloudy, dreary day is expected again today across much
of the area. High pressure across eastern Canada will continue
to nose its way down the eastern seaboard, while a weak area of
low pressure to our south moves offshore and slowly drifts out
to sea. There is a stationary boundary to our south that will
remain to our south with an occluded frontal boundary
approaching from the west. There could be a couple of periods
for a scattered showers today. First this morning across the
south as a short wave moves across the Delmarva, north of the
low to our south. This could create some scattered showers
mainly across the southern areas this morning. Additional
showers could approach the area this afternoon ahead of the
approaching occluded front and associated short wave/vorticity
impulse. Instability is weak this morning, but there is a small
chance of an isolated lightning strike. The better chance for
thunderstorms is late this afternoon and evening, especially
across the western half of the area as the front approaches.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
The occluded front continues to weaken and dissipate as it
approaches the area from the west this evening and overnight.
Nevertheless, there continues to be some weak instability
forecast and as there will continue to be some vorticity
affecting the area, there could be enough lift to create some
scattered showers and an isolated thunderstorm during the
evening. The precipitation will then likely dissipate through
the night. However, there could be some patchy fog develop
during the night with very saturated air remaining across the
area.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
A prolonged period of unsettled weather on tap for the long
term.

Deep trough over the Great Lakes presses east on Wednesday,
pushing a cold front through the Ohio Valley and into the
Northeast/Mid-Atlantic. Low pressure develops at the base of
the trough and moves off the Mid-Atlantic coast during the day.
Scattered showers and thunderstorms develop in the afternoon,
and then move offshore with the passage of the cold front
Wednesday evening.

Upper trough then in place over the Northeast as surface high
pressure builds across the area with dry conditions Thursday
through Friday. Temperatures will be near normal on Thursday,
and then will warm up several degrees above normal on Friday as
return flow sets up behind the departing high.

From there, upper trough flattens out as low pressure
approaches from the west. Aided by upper level shortwave energy,
scattered afternoon showers and thunderstorms look to encroach
from the west. Most of the models are holding off the bulk of
the precip until after 18Z, and latest guidance seems to be
holding the bulk of the precip off until after 00Z Saturday.

Wet weather sets up for the weekend as a series of low pressure
systems work their way across the region. There are some timing
differences among the GFS/ECMWF/CMC-GDPS, but the general trend
is for activity through the weekend. Given the low confidence
due to the timing differences, will generally carry chance PoPs
Saturday through Monday, but the models do seems to be keying in
on a more developed area of low pressure passing through the
East Coast sometime Sunday night through Monday, and will carry
the highest PoPs then.

Near normal temps expected through the weekend, but then below
normal temps expected for the start of the new week due to the
clouds/rain.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Low MVFR to IFR conditions are in place across the TAF sites as
an abundance of low level moisture has kept low clouds across
the area. Any sites that are not IFR are expected to drop to IFR
through the early morning hours and remain IFR through the TAF
period. Scattered showers are possible through the day. A line
of showers and thunderstorms may develop to our west this
afternoon, but may have a hard time making their way into our
area. At least not until this evening. So while there is a
chance of thunderstorms late this afternoon and into this
evening, especially across the west, we have kept them out of of
the forecast at this time.

Winds will generally be out of the east to southeast through today
around 5-10 knots.

OUTLOOK...

Wednesday...Improving conditions in the morning, then sub-VFR
conditions possible in the afternoon in scattered
showers/thunderstorms.

Wednesday night...Scattered showers/thunderstorms in the
evening, then VFR.

Thursday through Thursday night...VFR.

Friday through Saturday...Scattered showers and thunderstorms.

&&

.MARINE...
The Small Craft Advisory has been extended through 12 noon for
the northern New Jersey Atlantic coastal waters, and through 6
pm for the remainder of the New Jersey and Delaware Atlantic
coastal waters. After that, the seas are expected to be below 5
feet. Winds could gust around 20 knots through today, but will
likely remain below 25 knots.

OUTLOOK...

Wednesday through Thursday...No marine headlines anticipated.
Scattered showers and thunderstorms possible Wednesday afternoon
and evening.

Friday through Friday night...Small Craft Advisory conditions
possible due to wind gusts greater than 25 KT and seas building
to around 5 ft. Scattered afternoon/evening showers and
thunderstorms.

Saturday...Sub-SCA conditions expected. Scattered showers and
thunderstorms.

RIP CURRENTS...
The potential for the development of dangerous rip currents is
low for today.

&&

.TIDES/COASTAL FLOODING...
As astronomical tides continue to fall, the threat for coastal
flooding will be reduced, even through the onshore flow
continues. Therefore, no Coastal Flood Advisory is anticipated
for tonight.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory for hazardous seas until 6 PM EDT this
     evening for ANZ452>455.
     Small Craft Advisory for hazardous seas until noon EDT today
     for ANZ450-451.

&&

$$
Synopsis...MPS
Near Term...Robertson
Short Term...Robertson
Long Term...MPS
Aviation...Robertson/MPS
Marine...Robertson/MPS
Tides/Coastal Flooding...


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