Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 261401
Area Forecast Discussion
National Weather Service Mount Holly NJ
1001 AM EDT SUN JUN 26 2016
High pressure was centered over the mid-Atlantic and New England
this morning. The high will move offshore tonight and Monday. Low
will track across northeastern Canada early in the week. The cold
front from this system will slowly progress through the area
Tuesday before moving off the coast by early Wednesday. High
pressure returns later Wednesday into Thursday. Another cold front
is expected to approach from the northwest Friday and then move
through sometime next weekend.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
No big changes today as quiet weather remains in across the area
with high pressure in control. We did raise max temperatures a
degree or two in most areas based on 925 mb temps and latest near
term guidance. Some cirrus will move across the area during the
day, with some cumulus development possible, but it should still
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
The high pres moves ewd tonight as low pres moves acrs ern Canada.
Its assocd cdfnt will be approaching from the w by the end of the
pd. However, overnight still looks dry and mainly clear.
.LONG TERM /MONDAY THROUGH SATURDAY/...
The mean upper pattern across the CONUS through the end of the week
will feature persistent ridging along and west of the Rockies and
troughing centered over the Great Lakes. This setup will keep the
heat over the western U.S., well away from the forecast area over
the next seven days. Temperatures in the northern mid-Atlantic
region are expected to be near normal (generally highs in the 80s
and lows in the 60s) for the duration of the long-term period. The
large-scale pattern signals at least a potential for somewhat
unsettled conditions with several chances for precipitation to the
area from Monday afternoon through part of Wednesday and then again
Friday into Saturday. However, the smaller-scale details will
determine exactly how unsettled it will be. However, the appreciable
spread seen in the model guidance (e.g., fropa timing issues and
lack of clarity on the mesoscale) casts some uncertainty on exactly
how unsettled the week will be.
On Monday, shortwave energy rounding the base of the large-scale
trough will move into the upper Midwest. At the surface, this system
will feature a cold front that will be advancing southeastward
across the Great Lakes region as well as a pre-frontal trough that
sharpens along the lee side of the Appalachians. While there are
timing differences between operational models, most of the guidance
shows a band of precipitation ahead of the pre-frontal trough that
arrives in our western zones of eastern PA and far northwest NJ late
in the day Monday. Once again removed any mention of thunder from
the forecast for the daytime on Monday with the mid-level subsidence
inversion providing a cap for convection while our area is
positioned underneath the ridge. There is a slight chance that a
thunderstorm develops Monday night, especially across eastern PA and
the Delmarva, as modest elevated instability arrives in conjunction
with the surface trough.
The 00Z guidance has come into better agreement regarding the timing
of the cold front as it passes through the area Tuesday. Except for
the 00Z NAM, the latest guidance has trended toward a more
progressive solution. Although the front slows down as it approaches
the East Coast on Tuesday as a result of downstream blocking over
the western Atlantic Ocean, it likely will not have the chance to
stall over the area as a weak wave of low pressure that develops
along the front should provide a push offshore once the low moves
northeast of the area Tuesday night. Expect scattered showers and
thunderstorms to develop ahead of the front during peak heating
Tuesday afternoon and then continue into Tuesday night. The threat
of heavy rain is trended lower with the front no longer expected to
stall over the area.
On Wednesday, we expect precipitation to end and skies to clear from
west to east behind the front. Dry conditions continues through
Thursday night as high pressure builds in from the Midwest and
The longwave trough sharpens over central Canada-Great Lakes region
late in the week as more shortwave energy digs around the back-
side of the trough. Chances for showers and storms increase Friday
afternoon and Saturday as a cold front approaches from the northwest.
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
VFR conditions continue across the TAF sites today and tonight.
Some cirrus will move across the area during the day, with some
cumulus development possible, but it should still look sunny.
A S to SW wind will increase durg the day but will remain under
10 kts. After sunset wind will decrease to under 5 kts once again.
Monday through Tuesday night...Temporary/local MVFR or IFR
restrictions possible with scattered showers and storms. Showers
look to arrive into our western terminals late Monday afternoon and
I-95 terminals Monday night. Best chance for thunderstorms appear to
be Tuesday afternoon and evening.
Wednesday and Thursday...VFR.
With high pres over the region today and moving over the waters
tonight, relatively tranquil conds are expected and no headlines are
Monday through Thursday... Winds and seas should remain below SCA
criteria. There is a chance for thunderstorm to impact the waters on
Tuesday, especially during the afternoon and night.
Light southerly winds will continue across the waters through
Sunday. We are expecting a low risk for rip currents today.