076
FXUS61 KPHI 170136
AFDPHI
Area Forecast Discussion
National Weather Service Mount Holly NJ
936 PM EDT Wed Apr 16 2025
.SYNOPSIS...
High pressure will build to our south Thursday, while nosing
its way northward into southeast Canada. This high will shift
offshore of the Mid Atlantic coast Thursday night into Friday as
a warm front lifts north of the area. Return flow sets up
across the east coast, before a cold front moves across the area
later Saturday then stalls to our south. This front will move
back northward as an occluded frontal system moves across the
area early next week. High pressure may briefly return for the
middle of the week.
&&
.NEAR TERM /THROUGH THURSDAY/...
935 PM...Cloud cover has been a bit slower to diminish and
recede northward this evening so sky cover grids were increased
some through this evening. Clearing should still occur
overnight, however. Otherwise, as of mid evening high pressure
was centered over the Great Lakes with a large area of low
pressure over Atlantic Canada. This is keeping a fairly strong
pressure gradient in place resulting in gusty winds. The
gradient gradually relaxes through tonight and Thursday as the
high gradually shifts eastward just to our southwest. As the
upper trough moves away this evening and heights increase, we
should also quickly lose our stratocumulus cloud deck, resulting
in mostly clear skies overnight. With winds potentially going
fairly light at least in more sheltered spots, along with the
aforementioned clear skies and low dew points, we`ll likely have
the colder spots across much of the region drop to freezing or
below. Given that we`re now in the growing season for much of
the region, opted to issue a "frost advisory", though really its
more of a "patchy freeze warning" as dew points will mostly be
a bit too high for widespread frost, and the wind may stay just
up enough to prevent frost anyhow. However, given we`ll likely
see at least some scattered spots radiate efficiently, it seems
like a reasonable "heads up" regarding temps tonight. Some areas
in the advisory likely stay above freezing with no frost, for
sure, but cold spots will need to take precautions for sub-
freezing temps. A tricky forecast for sure.
Thursday will be a much nicer looking day, at least, with high
pressure and rising heights helping promote wall-to-wall
sunshine. There will be enough of a gradient left on the north
side of the high, combined with efficient mixing of the dry air
under the strong April sun, to bring some gusty winds back, but
only 20-30 mph at most, versus the 30-40 mph gusts we`ve seen
today. Temps will also rise 5-10 degrees compared to today, with
many areas reaching near or above 60. Overall, a much nicer day
than today, though still a bit cool for mid-April.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
High pressure begins to build offshore of the Mid Atlantic coast
Thursday night, while beginning to nose its way northward across the
area into southeast Canada. The high will fully shift offshore
Friday as a warm front moves north of the area. While dry weather is
expected Thursday night and most of Friday, there could be a few
showers associated with the warm front for portions of northeast
Pennsylvania and northern New Jersey during the afternoon Friday.
Return flow sets up across the area Friday into Saturday, before a
cold front moves into the area later Saturday into Saturday night.
Shower chances increase across the area for Saturday into Saturday
night.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The front pushes south of the area Sunday, while high pressure may
briefly affect the area bringing a brief rain free forecast.
However, this front will return back northward as an occluded
frontal system moves across the Mid Atlantic region Monday into
Tuesday as a low pressure system move across the Great Lakes region.
This will once again lead to an increase in rain chances early next
week. High pressure may briefly return for the middle of next week,
bringing a brief period of dry weather.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...VFR. Cigs breaking for mostly clear skies overnight,
with winds west-northwest 10-20 kts gusting to 30 kts early
dropping to 5-10 kts late. High confidence.
Thursday...VFR/SKC. West-northwest winds increasing back to
10-15 kts with gusts up to 25 kts. High confidence.
Outlook...
Thursday night-Friday night...VFR conditions.
Saturday-Saturday night...Chance of showers which may lead to sub-
VFR conditions.
Sunday-Sunday night...Mostly VFR conditions.
Monday...Sub-VFR conditions possible with a chance of rain.
&&
.MARINE...
The winds have diminished so the Small Craft Advisory that was
in effect has been cancelled. We should remain below advisory
criteria as high pressure builds overhead later tonight through
Thursday.
Outlook...
Thursday night...Sub Small Craft Advisory conditions expected.
Friday-Saturday night...Small Craft Advisory conditions due to winds
and waves likely.
Sunday-Monday...Sub Small Craft Advisory conditions are likely, but
seas may be close to advisory levels.
&&
.FIRE WEATHER...
Today, the fuels were deemed too moist for a Special Weather
Statement, but with another windy dry day behind us, they will
likely have dried out some more for Thursday, which will feature
both lower winds but lower humidity. Winds will be about 10 mph
lighter (gusting 20-30 mph instead of 30-40 mph) and RH`s about
10 percent lower (reaching 20-30 percent versus today`s 30-40
percent). In addition, Thursday will feature full sun with
temperatures rising towards 60. With several days of mostly dry
weather behind us by then, we`ll need to reach out to fire
weather partners early in the day to see if fuels have dried
enough to support a Special Weather Statement.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory from 2 AM to 9 AM EDT Thursday for PAZ060-070-
071-101>104-106.
NJ...Frost Advisory from 2 AM to 9 AM EDT Thursday for NJZ012-013-
015>022-027.
DE...Frost Advisory from 2 AM to 9 AM EDT Thursday for DEZ001.
MD...None.
MARINE...None.
&&
$$
SYNOPSIS...Robertson
NEAR TERM...Fitzsimmons/RCM
SHORT TERM...Robertson
LONG TERM...Robertson
AVIATION...Fitzsimmons/RCM/Robertson
MARINE...RCM/Robertson
FIRE WEATHER...