Forecast discussion
What forecasters are seeing
Plain-English forecast narrative from the local NWS office. Issued by NWS PHI.
332
FXUS61 KPHI 100756
AFDPHI
Area Forecast Discussion
National Weather Service Mount Holly NJ
356 AM EDT Wed Jun 10 2026
.WHAT HAS CHANGED...
A Heat Advisory has been issued for portions of the region,
which is in effect for Thursday through Friday.
Aviation section updated for the 06Z TAFs.
A Small Craft Advisory has been issued for the Atlantic coastal
nearshore waters.
&&
.KEY MESSAGES...
1. Scattered showers and thunderstorms will develop this
afternoon and early evening, with a Marginal Risk of severe
thunderstorms.
2. Dangerous heat and humidity is expected for portions of the
region on Thursday and Friday.
3. Chances for thunderstorms continuing Thursday through
Friday, including an increasing threat of severe thunderstorms
both days. The weekend has trended drier.
&&
.DISCUSSION...
KEY MESSAGE 1...Scattered showers and thunderstorms will
develop this afternoon and early evening, with a Marginal Risk
of severe thunderstorms.
A weak shortwave trough will propagate through a broader ridge
aloft this afternoon and evening. At the surface, a warm front
will lift north of the area today with high pressure offshore,
allowing for deep moisture return amid strengthening warm
advection.
Following some isolated morning showers, dewpoints will surge to
near 70 degrees by this afternoon as the warm front lifts north.
Considerable cloud cover will keep temperatures at bay though,
with highs mainly in the mid 80s for most areas. The dewpoints
will still make for an unpleasantly muggy day.
The high humidity will result in an unstable airmass later
today despite the cloud cover. Scattered showers and
thunderstorms are forecast to develop by mid to late afternoon
and early evening aided by forcing aloft from the shortwave
trough. Instability won`t be overly impressive, mainly around
1000-1500 J/kg. More importantly, deep layer shear is weak, only
around 10-20 kts. So anticipate the convection will be largely
disorganized and single to multi-cellular in nature. DCAPE is
modest at best, so cold pools won`t be too strong especially
given a shallow mixed layer today.
Nevertheless, cannot completely rule out a few stronger storms
producing marginally severe, damaging wind gusts from water
loaded downdrafts. If a cluster of storms can congeal into a
broken line of sorts, this could be a focus for locally damaging
wind gusts. PWats will be quite high near 2", so brief blinding
downpours will also be possible with any stronger storms today
which could cause some urban or poor drainage flooding. The main
timing for this activity looks to be from around 4-10 PM. SPC
maintains a Marginal Risk (1 out of 5) for severe storms for the
entire forecast are today.
Warm and muggy tonight with lows in the mid 60s to low 70s. Some
fog or low clouds may develop late, especially near any areas
that get a decent amount of rain during the day.
KEY MESSAGE 2...Dangerous heat and humidity is expected for
portions of the region on Thursday and Friday.
In general, mid-level ridging is expected to build into the
region during the middle and latter part of the week. However,
guidance has been trending southward with placement of an upper-
low over Canada and associated troughing over the CONUS, and
therefore featuring a slightly weaker ridge axis through our
region. At the surface, the region will largely be under the
influence of high pressure centered over portions of the
Southeast.
Despite this, dangerous heat is still expected across the area
on Thursday and Friday. Temperatures on both days look to climb
into the low to mid 90s across most of the area, though highs
may be a smidge warmer on Friday compared to Thursday. Dew
points will start out in the low to mid 70s, but with afternoon
heating and mixing, should mix down to the upper 60s and low
70s. This still results in max heat index values from 95 to 104
degrees across the majority of the area, outside of the Poconos.
The greatest threat for heat indicies over 100 degrees will be
found across southeast PA, central and southern NJ, and
Delmarva. This level of heat and humidity can become dangerous
quickly for sensitive individuals and those outdoors for
extended periods of time. A Heat Advisory has been issued to
highlight this threat, which is in effect from Thursday through
Friday. The exception is for coastal Monmouth County, which is
only in effect for Thursday.
A cold front is forecast to move through the region late Friday,
which will is expected to knock temperatures and dewpoints down
several degrees. Though it will still be hot with highs upper
80s to low 90s over the weekend, dewpoints will return to more
comfortable levels, minimizing the threat for additional heat
headlines.
KEY MESSAGE 3...Chances for thunderstorms continuing Thursday
through Friday, including an increasing threat of severe
thunderstorms both days. The weekend has trended drier.
The pattern in place will continue to support convection
chances across the region Thursday through Friday. Much of this
activity looks to be in the form of diurnally driven
convection, though better synoptic forcing will arrive on
Friday.
The next opportunity for storms following today comes Thursday.
Large scale forcing and shear are expected to remain relatively
weak, however we`ll have a convectively enhanced shortwave from
remnant convection upstream in the Midwest to contend with. This
will help improve forcing at the mesoscale. Hotter temperatures
and high dewpoints will yield steeper low level lapse rates.
This is a pretty typical severe thunderstorm setup for our
region, and will likely trigger at least some diurnally driven
convection. Exact details remain unclear depending on how things
evolve upstream today, but given the increasing risk, the Storm
Prediction Center has upgraded the entire region in a SLIGHT
risk. Damaging winds will likely be the main threat, but large
hail and a brief tornado cannot be ruled out.
On Friday, the region is expected to begin feeling the
influence of the upper trough to the west of the region, in
addition to a cold front that will be approaching from the west.
Scattered showers and storms may focus near and ahead of this
boundary, and with strong destabilization and slightly better
wind fields aloft, a severe threat will once again materialize.
SPC has our entire area highlighted in a SLIGHT risk of severe
thunderstorms. Details remain unclear about how Friday`s
convection may evolve.
Guidance has trended considerably drier for much of the weekend
in wake of the cold front, so it now appears that much of the
weekend will be dry. However, another front may approach towards
the end of the weekend and into early next week, with more
chances of showers and storms returning next week.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Through 12Z...Generally a VFR forecast. A few isolated showers
around, but no restrictions expected with this activity. South
winds near 5 kts. High confidence.
Today...VFR initially. MVFR CIGs develop from west to east
starting right after 12Z for KRDG/KABE, and MVFR CIGs spread to
KTTN/KPNE/KPHL/KILG. One wave of SHRA may impact
KRDG/KABE/KTTN/KPNE/KPHL and KILG in the morning, and will carry
PROB30 groups for those terminals for potential SHRA and lower
ceilings. Scattered thunderstorms will then impact the
terminals in the afternoon, and will carry TEMPO groups for
this. S to SW winds 5 to 10 kt in the morning, increasing to 10
to 15 kt with gusts up to 20 kt in the afternoon. Low
confidence on timing and restrictions resulting from any SHRA
and TSRA.
Tonight...There should be a period of VFR conditions before 06Z
following the afternoon/evening storms, however some low stratus
or fog may develop at some terminals later. Winds southwest
near 5 kts. Low confidence.
Outlook...
Thursday through Friday night...Prevailing VFR expected through
the period. Brief periods of sub-VFR conditions are possible,
with isolated to scattered showers and thunderstorms during the
afternoon and evening hours.
Saturday through Sunday...VFR. No significant weather expected.
&&
.MARINE...
Increasing southerly winds and building seas are forecast as the
day progresses. For the Atlantic coastal waters, winds gusting
up to 25 kts and seas near 4-5 feet are expected. A Small Craft
Advisory was issued to highlight these conditions from 2 PM
through midnight. Some isolated thunderstorms may impact the
nearshore waters and Delaware Bay this evening. Winds and seas
lessening overnight.
Outlook...
Thursday through Sunday...No marine headlines anticipated.
Winds will generally remain between 5-15 kt through Saturday,
with gusts up to 20 kt possible on Sunday. Seas generally around
2-3 feet. Isolated to scattered showers and thunderstorms
possible on Thursday and Friday. Fair weather expected for
Saturday and Sunday.
Rip Currents...
For today, southerly winds increase to 10 to 20 mph with gusts
up to 25 mph, especially in the afternoon. Breaking waves will
vary between 2 to 3 feet. While there will be a light easterly
swell in the morning, a more dominant southerly swell around 7
to 8 seconds should propagate northward in the afternoon. Given
these conditions, have opted to go with a MODERATE risk for the
development of dangerous rip currents for all beaches.
For Thursday, southwesterly winds diminish to around 10 to 15
mph. Breaking waves around 1 to 2 feet with a southerly swell
around 6 to 7 seconds. Given the lighter conditions, have opted
to go with a LOW risk for the development of dangerous rip
currents for all beaches.
Ocean water temperatures are gradually increasing, but remain
mostly in the 60s.
For specific beach forecasts, visit weather.gov/beach/phi
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory from 11 AM Thursday to 8 PM EDT Friday for
PAZ060>062-070-071-101>106.
NJ...Heat Advisory from 11 AM Thursday to 8 PM EDT Friday for
NJZ001-007>010-012-013-015-017>020-027.
Heat Advisory from 11 AM to 8 PM EDT Thursday for NJZ014.
DE...Heat Advisory from 11 AM Thursday to 8 PM EDT Friday for
DEZ001.
MD...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to midnight EDT
tonight for ANZ450>455.
&&
$$
DISCUSSION...DeSilva/MPS/Staarmann
AVIATION...MPS/Staarmann
MARINE...DeSilva/MPS/Staarmann