Decision Support Page for New Castle County

Forecast Discussion

974
FXUS61 KPHI 181034
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
634 AM EDT Fri Apr 18 2025

.SYNOPSIS...
High pressure will shift offshore Friday as a warm front lifts
northward Friday night. A southerly or return flow will then
set up across the east coast, before a cold front tracks through
the area Saturday night and Sunday. This cold front will stall
to our south on Sunday night and quickly move back northward, as
a warm front, on Monday. A cold front will follow on Monday
night. High pressure will then return on Tuesday and Wednesday,
before weakening on Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
With sunrise now underway, temperatures will be rising into the
40s over the next hour or so and any patchy frost will melt
off. Will therefore go ahead and cancel the Frost Advisory that
was in effect until 8 am.

Otherwise, high pressure will be centered off the Mid-Atlantic
and Southeast coasts. Low pressure over the Upper Midwest and
Great Lakes will approach from the west. A warm front out ahead
of that low will lift north through the region this evening, and
then the cold front continues to approach behind it.

Mostly sunny skies on tap for today. The pressure gradient will
tighten later today between the offshore high and low pressure
moving through the Great Lakes and central Canada. South winds
will increase to 15 to 20 mph with 25 to 30 mph gusts. Warm air
advection will be underway, and highs today will be in the upper
60s to low 70s, except in the low 60s in the higher elevations
of the southern Poconos, and in the upper 50s to low 60s along
the coasts.

Winds diminish after sunset and will generally range from 10 to
15 mph. High clouds will spread in from the west. Lows tonight
will be fairly warm, generally in the low to mid 50s for most of
the region, and in the mid to upper 50s in Delmarva.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
After the warm front moves northward Friday night, we are well into
the warm sector on Saturday as temperatures reach into the low 80s
for most. Winds will also be breezy on Saturday out of the southwest
with gusts at times reaching 25-30 mph. These winds do diminish
into Saturday night. A cold front moves through overnight
Saturday and not too much activity is expected with this front.
It will lack a lot of moisture and a passing shower looks to be
the extent of any precip. The potential for a passing shower is
mainly for the Poconos, parts of the Lehigh Valley, and NW New
Jersey. Lows Saturday night are mainly in the 50s.

A high pressure system briefly builds in from the north on
Sunday and that cold front that moves through Saturday night
stalls to the south of the area. We are 10-15 degrees cooler on
Sunday compared to Saturday with highs reaching the mid 60s to
low 70s and it does look to be a dry day.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A low pressure system approaches from the west on Monday which drags
a warm front northward during the day. The passage of this warm
front looks to lack a lot of moisture and mainly just adds in more
clouds. The cold front that follows leads to some rain showers
Monday evening into Monday night. There is the chance for an
isolated thunderstorm during this timeframe as well.

A high pressure system then builds in for midweek. We also start to
experience a stretch of mainly 70 degree highs for many Tuesday
through Thursday. Another cold front looks to move in from the west
on Thursday night which would lead to another potential for some
rain showers.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR. S winds less than 10 kt this morning will increase to
15 to 20 kt with 25 to 30 kt gusts by 18Z. Winds will diminish a
bit prior to 00Z. High confidence.

Tonight...VFR. S winds 10 to 15 kt. LLWS with SW winds 45 to 50 kt
at 2000 ft. High confidence.

Outlook...

Saturday...Sub-VFR conditions possible with some showers moving
through during the evening and into Saturday night. A south wind
will be gusting to 20-25 knots during the day.

Sunday...VFR conditions expected.

Monday...Sub-VFR conditions possible with some showers moving
through during the evening and into Monday night.

Tuesday...VFR conditions expected.

&&

.MARINE...
Sub-Small Craft Advisory conditions this morning with S to SW winds
10 to 15 kt. Winds then increase this afternoon to 15 to 20 kt with
25 to 30 kt gusts and SCA conditions will persist through tonight.
SCA goes into effect for all waters at 2 pm.

Outlook...

Saturday...Small Craft Advisory conditions continue for much of the
day Saturday.

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

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

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

&&

.FIRE WEATHER...
South winds increase this afternoon to 15 to 20 mph with 25 to 30
mph gusts. Surface dew points will rise into the low to mid 40s, and
with high temperatures in the upper 60s to low 70s, Min RH values
will range from 35 to 40 percent across most of the region, except
for the Pine Barrens of southern New Jersey, where Min RH values
will be 30 to 35 percent. Will reach out to the state fire weather
partners to see if fuels have dried sufficiently to warrant a
Special Weather Statement for the risk of rapid fire spread today.

On Saturday, Min RH values will be 40 to 45 percent with SW winds 15
to 20 mph with 25 to 30 mph gusts. On Sunday, Min RH values will be
30 to 35 percent with NW winds 10 to 15 mph with gusts up to 20
mph.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 6 PM EDT
Saturday for ANZ430-431-450>455.

&&

$$

SYNOPSIS...Guzzo
NEAR TERM...MPS
SHORT TERM...Guzzo
LONG TERM...Guzzo
AVIATION...Guzzo/MPS
MARINE...Guzzo/MPS
FIRE WEATHER...

Latest Observation at Wilmington

Data at: 0000 UTC 03 Sep 2023

METAR for:

KILG (Wilmington/New Castl, DE, US)

Text:

KILG 022351Z 17009KT 10SM CLR 23/18 A3009 RMK AO2 SLP190 T02330178 10283 20233 56008

Temperature:

23.3°C ( 74°F)

Dewpoint:

17.8°C ( 64°F) [RH = 71%]

Pressure (altimeter):

30.09 inches Hg (1019.0 mb) [Sea level pressure: 1019.0 mb]