Georgetown, Delaware 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

487
FXUS61 KPHI 111937
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
337 PM EDT Fri Apr 11 2025

.SYNOPSIS...
Low pressure moves up the coast into Saturday morning, then it
slowly moves away from our area later Saturday and Saturday night.
High pressure arrives into our region later Sunday into Monday
before shifting offshore. A cold front crosses our region later
Monday night into Tuesday followed by a secondary cold front Tuesday
night. High pressure builds in during Wednesday, then a cold front
should arrive on Friday.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
Off and on precipitation will continue through this period as
the coastal low makes gradual progress further north and east.

What has changed: expanded the mention of snow and slightly
increased snow amounts for areas mostly north of the I-78
corridor.

Timing: Precipitation will continue to expand northward through
this evening. The period of the most widespread precipitation
will be this evening through the overnight hours. Towards
daybreak, a dry slot may begin to progress into the coastal
plains. While there will still be off and on rain once it does,
it should be light and much less widespread. Areas northwest of
the Fall Line however, could see banding on the NW side of the
low continue into mid day. Once we get to mid day, expect the
precipitation to gradually diminish in coverage from west to
east as the low begins to get further from the region.

Precipitation Type: High res guidance is colder than most
coarser guidance especially in areas northwest of the fall line.
Given the set up, favored the colder guidance, and thus have at
least some snow mention from the I-78 corridor northward
overnight. Otherwise, expect primarily rain.

Snow amounts/impacts: Relatively warm ground this late in the
season will limit how much snow will accumulate. However, even
this morning (which was a lighter event than what we are
expecting tonight) isolated areas in Monroe County had 1 - 2
inches of accumulation mostly on grassy surfaces. Most areas
should once again see less than one inch, but Carbon, Monroe,
and Sussex (NJ) counties, isolated areas in the higher terrain
may see 2 - 4 inches. Held off on any advisory at this point as
it will be mostly accumulating on grassy surfaces again. That
being said, a light coating on roads (especially bridges) is
possible.

Flooding concerns: The threat for flooding has decreased over
the last few model runs. Additional precipitation amounts are
expected to be between 0.5 and 1.25 inches. As long as rain
rates don`t get significantly higher than what we are currently
forecasting, this should be more of a beneficial rain than
anything else. Will be watching more urbanized/poor drainage
areas for any isolated flooding instances.

Temperatures: Even in areas where the dry slot works its way
into the region, persistent cloud cover will mean a limited
diurnal range tonight, tomorrow, and into tomorrow night.
temperatures throughout the period are going to be in the 30s
and 40s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Improving conditions along with rebounding temperatures.

As a closed low continues to shift farther off to our east during
Sunday, the flow aloft will gradually shift from cyclonic to more
anticyclonic. As some mid level ridging starts to approach from the
west later Sunday, surface high pressure will begin to build in.
Prior to that though, lingering moisture, especially trapped under
an inversion, should hold some cloud cover in Sunday although some
breaks should begin in the afternoon. As the cloud bases rise some
and the influence of the closed low lessens, temperatures will
rebound Sunday afternoon but still be below average. There will also
be northwesterly breeze, although this will be diminishing with time
given a relaxing pressure gradient and the arrival of high pressure.
Some clouds should persist Sunday night and with dew points
recovering some the temperatures should not drop as much.

As we go through Monday, the axis of a weak mid level ridge crosses
our area. This will take surface high pressure offshore by the end
of the day with it even becoming more centered well to our south. An
upper-level trough, which will be amplifying eastward, should close
off in the vicinity of the Great Lakes region during Monday. This
will drive surface low pressure across the Great Lakes and into
adjacent Canada by daybreak Tuesday. A cold front tied to this low
will be crossing our area Monday night into Tuesday. An increasing
southwesterly flow will assist in boosting the warm air advection
and therefore increasing ascent. At least some showers should arrive
from west to east across much of the region by later Monday night.
The timing is not ideal for thunder, and since the main upper-level
trough is hanging back so far to the west this should really limit
the instability due to less cooling aloft (greatest chance for some
thunder should be more toward the Ohio Valley). Overall, some
increasing chances for showers during Monday night with the arrival
of the aforementioned cold front. High temperatures Monday are
forecast to be in the 60s for most of the area (even 70 in parts of
Delmarva), with it cooler along the coast and in the higher
elevations.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Summary...Mild to start followed by some cooling. Precipitation
chances mainly on Tuesday and Friday.

Synoptic Overview...A potentially strong upper-level trough is
forecast to settle into the East Tuesday and Wednesday, then it
departs into Thursday as the flow aloft becomes more zonal. Another
upper-level trough, potentially strong once again, is then forecast
to arrive into the East during Friday. At the surface, a cold front
should be working its way across the area to start Tuesday followed
by a stronger cold front Tuesday night into early Wednesday. High
pressure arrives Wednesday night into Thursday, then a cold front
arrives during Friday.

For Tuesday and Wednesday...A sharpening upper-level trough, which
could be rather strong, shifts into the East during Tuesday and
continues for much of Wednesday. This will drive surface low
pressure well to our north, however an initial cold front looks to
be continuing to shift east and offshore to start Tuesday. Some
showers should occur, however the colder air looks to lag due to the
main trough axis still to our west Tuesday. As a result, Tuesday
should be on the milder side for most if not all of the area. A
secondary cold front, stronger but drier, moves through Tuesday
night into early Wednesday. This should have little or no showers
with it as the plume of deeper moisture and lift are well offshore.
A gusty wind as well as cooler air settles in for Wednesday. As the
cyclonic flow aloft weakens Wednesday night and surface high
pressure starts to build in from the west and south, the winds will
diminish Wednesday night. How much of this occurs will determine how
cold it will get, however there is some frost and/or freeze
potential for at least parts of the area.

For Thursday and Friday...Following the departure of the
aforementioned upper-level trough, the flow aloft turns zonal for a
time Thursday. This will result in Thursday turning a bit milder
after a cold start. Given the fast flow, the next upper-level trough
is forecast to be amplifying into the East as we go through Friday.
This once again looks to drive surface low pressure to our north,
however a cold front will be arriving during Friday. There does not
appear to be a strong surge of warm air ahead of this system,
however if it does indeed become rather potent and arrives during
peak heating then perhaps some thunder accompanies the cold front.
There are some hints in the model guidance that a pre-frontal trough
may arrive ahead of the actual cold front, which could assist in
focusing more showers. The colder air aloft may end up lagging
behind, however will need to monitor the strength of this as it
could bring some stronger convection to parts of our region.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Remainder of Today...IFR ceilings prevailing at most terminals
through 00Z. A few terminals have been hovering right around 1 kft,
but still expect that ceilings will lower to IFR areawide by 00Z at
the latest. Widespread rain and visibility reductions to 3-4 SM in
the heaviest rain. East-northeast wind 10-15 kt. Some gusts near 20
kt are possible. Moderate confidence.

Tonight...IFR at all terminals. LIFR ceilings are possible 05Z-12Z,
but confidence is low regarding the occurrence, timing, and
placement of any LIFR restrictions. Widespread rain continues with
visibility reductions to 3-4 SM. Northeast wind 10-15 kt with gusts
to 20 kt. Moderate confidence overall, low confidence with regard to
timing and placement of largest cig/vsby reductions.

Saturday...IFR ceilings will continue to prevail through most of the
day, though some gradual improvement is possible, especially after
15-18Z or so. Rain will become less widespread after about 15Z but
widespread showers and patchy drizzle will likely remain further
into the afternoon with continued visibility reductions at times.
Ceilings will begin to improve towards MVFR from west to east
near/after 00Z. Moderate confidence.

Outlook...

Saturday night...Sub-VFR ceilings should gradually improve
overnight.

Sunday...VFR but with lingering cloud cover. Northwest wind gusts
up to 20 knots during the day.

Monday and Tuesday...Some showers Monday night into Tuesday may
result in some times of sub-VFR conditions. Westerly wind gusts up
to 25 knots during Tuesday.

Wednesday...VFR. West northwest winds 15-20 knots with gusts up to
30 knots, diminishing at night.

&&

.MARINE...
Winds will continue to increase, with the peak of the winds expected
generally between midnight and noon. Forecast is still on track
with gale force gusts generally confined to areas north of
Little Egg Inlet.

With (at least initially) a NE wind direction, expect seas to
increase considerably as well, with seas above 9 feet in the
areas with the strongest winds.

Winds and seas will begin to diminish starting Saturday
afternoon, but Small Craft Advisory conditions are expected to
continue across the area for most, if not all of the day.

Outlook...

Saturday night...Small Craft Advisory conditions for at least portions
of our waters.

Sunday...The conditions are anticipated to be dropping below Small
Craft Advisory criteria for all areas.

Monday...The conditions are anticipated to be below Small Craft
Advisory criteria.

Tuesday...Small Craft Advisory conditions should develop at night,
mainly due to wind gusts to around 25 knots.

Wednesday...Small Craft Advisory conditions probable.

&&

.TIDES/COASTAL FLOODING...
Spotty minor coastal flooding possible during the Saturday
evening high tide. A full moon tide along with persistent
northeasterly winds could result in minor inundation along the
coastlines of New Jersey and Delaware.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT Saturday for ANZ430-431.
     Small Craft Advisory until 6 PM EDT this evening for ANZ450-
     451.
     Gale Warning until 6 PM EDT Saturday for ANZ450-451.
     Small Craft Advisory until 6 AM EDT Sunday for ANZ452>455.

&&

$$

SYNOPSIS...Gorse
NEAR TERM...Johnson
SHORT TERM...Gorse
LONG TERM...Gorse
AVIATION...Cooper/Gorse
MARINE...Gorse/Johnson
TIDES/COASTAL FLOODING...WFO PHI