-- Discussion containing changed information from previous version are highlighted. --
954
FXUS61 KPHI 171514
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1114 AM EDT Mon Jun 17 2024

.SYNOPSIS...
Surface high pressure southeast of New England will slide south
on Wednesday and will remain anchored offshore into next
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
No significant changes needed to the forecast so far today. Only
minor houly adjusments needed.

A large surface high pressure system continues to drift to the
north and east of the region. This will lift a warm front
through the area during the day today with southerly warm air
advection developing and starting to usher in the higher heat
this week.

With the broad ridge aloft building, and ample dry air, the
sensible forecast remains dry today. Temps this afternoon should
easily warm into the upper 80s to low 90s under mostly clear
skies. By mid afternoon, mixing in the boundary layer should be
strong enough to occasionally see winds gust to 15-20 mph
however its unlikely to be consistently gusty.

By sundown the boundary will start to decouple so the gust
potential should quickly weaken. However the warm air advection
from the offshore surface high should continue through the
evening keep temps fairly stable early before cooling into the
mid 60s overnight.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
1030 mb surface high pressure will be centered some 560 miles
east of Nantucket Island on Tuesday as a 500 mb ridge envelops
the East Coast. A warm front will lift north through the region
on Tuesday, and an increasingly hot and humid airmass will begin
to spread into the region.

High temperatures both Tuesday and Wednesday will generally top
off in the low to mid 90s mainly along the I-95 corridor as
well as for areas north and west of the I-95 corridor. For
southern New Jersey and Delmarva, highs will top off in the
upper 80s to low 90s. Meanwhile, surface dew points will
generally climb into the mid and upper 60s during peak heating
of the day. As a result, max heat index values will be in the
upper 90s to around 100 for the hotter areas along the I-95
corridor and inland, while max heat index values will be in the
low to mid 90s for the southern portions of the forecast area.

Will keep the Heat Advisory in place for Tuesday and the
Excessive Heat Watch in effect for Wednesday. It is becoming
more likely that The Excessive Heat Watch will be converted to a
Heat Advisory on Wednesday, but it is also the start of a
prolonged period of building heat.

Low temperatures at night will generally be in the low to mid
70s in Philadelphia and in the mid to upper 60s elsewhere. It
will remain quite humid at night, providing little relief.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Surface high pressure east of Nantucket Island will slowly
build south and will be some 550 miles east of Cape Hatteras by
the end of the week. Meanwhile, 500 mb ridge remains over the
East Coast until sliding south by Sunday as a cold front
approaches from the west.

During this time, a prolonged period of increasing heat and
humidity will build into the region. High temperatures will rise
into the mid and upper 90s on Thursday, and then into the upper
90s to around 100 on Friday and Saturday. By Sunday, the
hottest temperatures will slide south, and highs will climb into
the low to mid 90s. In terms of low level moisture, a light
south to southwest flow will prevail. Although dew points will
rise into the mid and upper 60s, then into the upper 60s to
around 70 by the weekend, it looks like dew points will not get
into the mid 70s. This results in max heat index values ranging
from around 100 to as high as 110 by Friday, then max heat index
values will abate somewhat over the weekend with conditions
below Heat Advisory criteria by Sunday.

Will keep the Excessive Heat Watch in effect through Saturday.

Meanwhile, low pressure will track across Canada, dragging a
trough down into southern Ontario and southern Quebec. Along
with some strong shortwave energy, some afternoon and evening
showers and thunderstorms will be possible Friday afternoon and
evening, then again on Saturday afternoon and evening. As a cold
front approaches from the west on Sunday, additional showers
and thunderstorms are possible. For now, PoPs will be capped at
chance.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR. South to southwesterly winds becoming occasionally
gusty mid afternoon.

Tonight...VFR. Light southerly flow.

Outlook...

Tuesday through Thursday...VFR.

Friday...VFR. Isolated afternoon/evening SHRA/TSRA possible at
KRDG/KABE/KTTN.
-- End Changed Discussion --

&&

.MARINE...
No marine headlines expected through Monday. South winds 10 to
20 knots this afternoon. Gust may touch 25kts on the northern
Atlantic waters, but with the colder sea surface temps, strong
mixing is not expected thus not expecting an SCA will be needed.
Seas 2-4 feet.

Outlook...

Tuesday through Friday...A prolonged period of sub-SCA
conditions on tap for the upcoming week. However, winds on
northern NJ ocean waters may approach SCA criteria during the
afternoon hours.

Rip Currents...

Winds will increase back to 10-15 mph with a bit of an onshore
component for the New Jersey beaches. With breaking waves around
2 to 3 feet a MODERATE risk for dangerous rip currents will
peak around low tide. With breaking waves expected to be 1-3
feet along the Delaware beaches we are forecasting a LOW risk.

For Tuesday, winds and breaking waves are anticipated to be
lower thus there is a LOW risk for the development of dangerous
rip currents is in the forecast.

Rip currents occur often in the vicinities of jetties and
piers. Utilize any guarded beaches if venturing out into the
water. For specific beach forecasts, visit weather.gov/beach/phi

&&

.CLIMATE...
Record high temperatures Tuesday.

Location          Record High (6/18)

Philadelphia, PA      96/1957
Allentown, PA         95/2018
Reading, PA           97/1957
Mount Pocono, PA      88/1957
Trenton, NJ           96/1957
AC Airport, NJ        95/2014
AC Marina, NJ         94/2014
Wilmington, DE        95/1957
Georgetown, DE        97/2014

Record high temperatures Wednesday.

Location          Record High (6/19)

Philadelphia, PA      100/1994
Allentown, PA         96/1994
Reading, PA           95/1929
Mount Pocono, PA      86/1929
Trenton, NJ           96/1994
AC Airport, NJ        96/1994
AC Marina, NJ         93/1952
Wilmington, DE        100/1994
Georgetown, DE        96/1952

Record high temperatures Thursday

Location          Record High (6/20)

Philadelphia, PA      98/1931
Allentown, PA         100/1923
Reading, PA           101/1923
Mount Pocono, PA      89/2012
Trenton, NJ           98/1923
AC Airport, NJ        95/2012
AC Marina, NJ         90/1908
Wilmington, DE        97/2012
Georgetown, DE        98/2012

Record high temperatures Friday.

Location          Record High (6/21)

Philadelphia, PA      99/1923
Allentown, PA         100/1923
Reading, PA           99/1923
Mount Pocono, PA      90/1953
Trenton, NJ           97/1923
AC Airport, NJ        97/1988
AC Marina, NJ         94/2012
Wilmington, DE        98/2012
Georgetown, DE        99/2012

Record high temperatures Saturday.

Location          Record High (6/22)

Philadelphia, PA      100/1988
Allentown, PA         95/1941
Reading, PA           96/1921
Mount Pocono, PA      90/1908
Trenton, NJ           99/1988
AC Airport, NJ        100/1988
AC Marina, NJ         92/1949
Wilmington, DE        98/1988
Georgetown, DE        97/2012

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory from 10 AM Tuesday to 6 AM EDT Wednesday for
     PAZ054-055-060>062-070-071-101>106.
     Excessive Heat Watch from Wednesday morning through Saturday
     evening for PAZ054-055-060>062-070-071-101>106.
NJ...Heat Advisory from 10 AM Tuesday to 6 AM EDT Wednesday for
     NJZ001-007>010-012-013-015>020-027.
     Excessive Heat Watch from Wednesday morning through Saturday
     evening for NJZ001-007>010-012-013-015>020-027.
DE...Heat Advisory from 10 AM Tuesday to 6 AM EDT Wednesday for
     DEZ001.
     Excessive Heat Watch from Wednesday morning through Saturday
     evening for DEZ001.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...MPS
NEAR TERM...Deal/Robertson
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...Deal/MPS/Robertson
MARINE...Deal/MPS
CLIMATE...