Scientific Forecaster Discussion
fxus61 kphi 241957
Area forecast discussion
National Weather Service Mount Holly New Jersey
357 PM EDT Sat Jun 24 2017
high pressure will attempt to build into the mid- Atlantic
region for tonight and Sunday. However some trofiness will
persist over the Great Lakes and New England through Tuesday.
Stronger high pressure is forecast to build in for Wednesday and
then move offshore Thursday and Friday. A frontal system
approaching from the northwest may bring a chance for showers
Friday and Saturday.
Near term /until 6 am Sunday morning/...
a shortwave surface ridge is expected to build close to the
region overnight. That combined with the continued dry air
advection in the wake of the cold front this morning means dry
conditions and clearing skies through the overnight hours.
Thanks to the drier conditions and clearing skies, temperatures are
expected to drop off a bit more than what we have seen the last few
nights. Low temperatures are expected to range from the upper 50s to
Short term /6 am Sunday morning through 6 PM Sunday/...
the surface ridge will weaken quickly as a mid and upper level
shortwave trough digs southeast towards New England. The lift
associated with this feature may be enough for convective
initiation across the Poconos and northwest NJ, but we aren't expecting
any widespread precipitation as we will remain quite dry
through the day tomorrow.
Temperatures tomorrow are expected to be near or just below
temperatures today as the northwesterly flow regime redevelops.
Long term /Sunday night through Saturday/...
Monday and Monday night...another cold front is expected move
through the region through this period. In the mid and upper levels,
a positively tilted short wave trough will be trailing close behind.
Despite ample lift and upper level support, do not expect too much
in the way of precipitation across the region primarily because we
are not expecting any significant moisture advection before this
An upper level trough remains over the eastern US on Tuesday
with some associated surface trofiness as well. Guidance
supports just a slight chance for showers or an isolated
T-storm. Then stronger surface high pressure builds in over the
mid-Atlantic region on Wednesday as the upper trof moves
offshore. At this time Wednesday looks to be dry with slightly
below normal temperatures continuing from Tuesday.
On Thursday and Friday the high pressure moves offshore and low
pressure moves across the Great Lakes. This sets up a southwest
flow around the sub-tropical ridge with increasing heat and
humidity towards the end of the week. A frontal system is
forecast to approach from the northwest but is not expected to
reach the area. However the increasing low-level moisture and
typical surface trof in the Lee of the mountains will make
conditions favorable for afternoon showers and T-storms,
especially north/west of phl. High temperatures a few degrees
above normal are expected Thursday through Saturday.
Aviation /19z Saturday through Thursday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
VFR conditions are expected through the taf period. Some mid level
clouds near or above 5000 ft above ground level may move over the region after 03z.
Winds are expected to subside to near or below 10kt by 00z. Wind
direction may back to westerly overnight. Around 18z tomorrow,
expect wind speeds to once again increase with 10g20kt possible for
much of the afternoon at all taf sites.
Sunday night through Monday night...mostly VFR conditions are
expected. There is a small chance for showers and thunderstorms
Monday and Monday night. If any move over the taf sites, MVFR or
lower conditions will be possible.
Monday and Tuesday...mostly VFR but a chance for tempo lower
conditions in isolated thunderstorms, mainly for Abe and ridge.
West wind mainly 10 kt or less.
Wednesday and Thursday...VFR condions expected. Light west winds
on Wednesday become southwest on Thursday with gusts to 20 kt
possible in the afternoon.
winds and seas are expected to subside below Small Craft Advisory criteria early
this evening. Once they do, expect conditions to continue below
criteria through the day tomorrow.
Sunday night through Monday night...winds and seas should
stay below Small Craft Advisory criteria.
Tuesday and Wednesday...winds and seas are forecast to remain
below Small Craft Advisory conditions.
Thursday...Small Craft Advisory conditions may develop in the afternoon.
A moderate risk for the formation of dangerous rip currents
continues through this evening. By tomorrow, decreasing swell and
off shore flow should lead to a low risk for the formation of
dangerous rip currents.
Marine...Small Craft Advisory until 6 PM EDT this evening for anz430-