Excessive Heat Watch 2, NWS Philadelphia/Mount Holly

Kent County, DE, New Castle County, DE, Sussex County, DE, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Delaware County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA

Area Forecast Discussion
National Weather Service Mount Holly NJ
228 PM EDT Fri Jul 12 2024

.SYNOPSIS...
Stationary front plagues the region into Saturday with several
waves of low pressure riding along it. Broad high pressure then
returns and persists through Tuesday before another cold front
approaches the area around the Wednesday-Thursday timeframe.

&&

.NEAR TERM /THROUGH SATURDAY/...
A frontal boundary has lifted northward into the area from the
coast. Bermuda high pressure will continue to advect a ribbon
of rich tropical moisture back into the region along and south
of this front as well. Meanwhile, a broad jet located to our
northeast will result in broad diffluence aloft, strengthening
through Saturday. Meanwhile, a closed upper low is passing by
just offshore.

Showers and a few thunderstorms continue to spread across the
area this afternoon. The heaviest rain has occurred near the
coast, which was farther south than anticipated for the daytime
period. Localized amounts of 3-5" of rainfall have been
observed. The showers and storms should continue into this
evening, however a break in activity is expected overnight
as a lull in synoptic forcing occurs. PWats will remain around
2-2.5", near climatological maxima, along with MUCAPE near 1,000
J/kg. The more robust showers and thunderstorms that develop
will be capable of producing very heavy rainfall, with rainfall
rates near 2" per hour. The threat for severe thunderstorms is
very low. PoPs were adjusted to match the latest guidance,
including a lull overnight.

Temperatures will remain below normal through this afternoon,
topping out in the upper 70s to low 80s in most areas. With all
the cloud cover and moisture around tonight, temperatures will
remain quite mild, with lows ranging from the low to mid 70s.
Light southerly winds through Saturday, though winds will become
light and variable at times.

While the heaviest rainfall so far today has occurred near the
coast, guidance continues to pinpoint the heaviest rainfall
potential from across portions of Delmarva and into the urban
corridor through early Saturday afternoon. An additional wave of
widespread heavy showers and thunderstorms is expected to impact
this area beginning around daybreak Saturday through around
midday. Widespread rainfall amounts near 1-2" can be expected,
with locally higher amounts up to 5" possible. Rainfall rates
may exceed 1-2" per hour at times. While much of the area has
been dry recently, the rainfall rates may lead to some areas of
flash flooding, especially in urbanized and poor drainage areas.
The Flood Watch remains in effect as previously issued through
2 PM Saturday to highlight this threat.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Surface stationary front and low pressure riding along it will
continue to plague the region Saturday. Luckily, the stationary
front should begin to dissipate some Saturday night as weak
surface high pressure builds in. Weak surface high pressure
looks to hold influence over us Saturday night through Sunday
night.

Overall, short term looks impactful for Saturday morning into
Saturday afternoon and rather benign thereafter, at least PoP
wise. The concern remains for moderate to heavy rainfall
Saturday leading to flooding concerns. Plenty of low-level
moisture, showers and storms will continue to stream northwards
from the south Saturday morning; storm motions will remain
relatively slow. Any area of rain will be more than capable of
producing heavy rainfall and localized flash flooding; grounds
cold very well be saturated from Friday night. Please see the
NEAR TERM for more details.

PoPs will begin to diminish later Saturday afternoon. The I-95
corridor and areas west should actually start to see clearing
skies in the late afternoon. Highs mainly in the mid to upper
80s can be anticipated. Other than for some areas near the coast
early on, no PoP is included in the forecast for Saturday
night. Fog formation across the region is possible Saturday
night with an overall saturated boundary layer, mostly clear
skies, and very light and/or calm winds.

Heat returns for Sunday with highs mainly in the low to mid 90s
across the region. With dewpoints in the 70s, heat indices will
once again climb back up. Right now, some areas of the I-95
corridor hit advisory criteria in the forecast for Sunday;
Sunday may be the first day advisories are needed. A stray and
isolated shower is not out of the question for Sunday and Sunday
night with the proximity of the decaying front, but the
forecast mainly remains dry.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The high heat and humidity returns for the beginning to midweek
time frame before a cold front crosses through Wednesday-
Thursday. Afternoon highs in the mid to upper 90s with dew
points in the 70s are anticipated for at least Monday and
Tuesday, maybe continuing into Wednesday depending on the timing
and placement of the mentioned cold front. With heat indices of
100-110 across the region, widespread heat headlines are
anticipated for Monday and Tuesday. Headlines may continue into
Wednesday as well. More seasonable conditions will likely return
once the cold front has crossed through.

Diurnally-driven thunderstorms are likely to occur each
afternoon, but with the lack of any forcing nearby, the threat
does not appear to be severe. Eventually, the cold front will
approach from the northwest Wednesday into Thursday, which may
result in a more widespread chance of showers/thunderstorms
across the region.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR conditions have generally prevailed thus far today,
however a trend toward more persistent MVFR conditions can be
expected through 00Z or so. Numerous showers and a few
thunderstorms will persist as well, with locally IFR conditions
possible with this activity. Winds will remain near 5 kts
favoring a southerly direction, although will be light and
variable at times. Moderate confidence on overall pattern, but
lower confidence on timing details.

Tonight...Conditions trending toward IFR by 06Z. A lull in the
shower activity is expected early in the night, however another
round is expected to develop after 09Z. Winds light and
variable, favoring a southerly direction. Moderate confidence.

Saturday...Initially MVFR to IFR conditions with potential for
heavy showers and thunderstorms through 18Z, then conditions
improve to VFR thereafter. Southerly winds near 5-10 kts.
Moderate confidence.

Outlook...

Saturday night...Sub-VFR possible due to fog formation.
Moderate confidence.

Sunday through Tuesday...Primarily VFR. A slight chance to
chance of a shower or thunderstorm on Monday/Tuesday. Otherwise,
no significant weather expected. Moderate confidence.

&&

.MARINE...
Southerly winds 10-15 kts with some gusts near 20 kts possible.
Seas will be around 4-5 feet through this evening, so we've
extended the Small Craft Advisory through 10 PM.

VSBY restrictions in showers and fog. Rain may be heavy at
times. Scattered thunderstorms possible as well.

Outlook...

Saturday night...SCA flag possible due to seas around 5 feet.
Some fog development possible Saturday morning and Saturday
night.

Sunday through Tuesday...No marine headlines expected. Winds up
to 20 kt and seas 2-4 feet.

Rip Currents...

South to southeast winds will range from 10 to 15 mph with
breaking waves of 2 to 4 feet. With the flow slightly onshore or
parallel to the shore in New Jersey, there is a MODERATE risk
for the development of dangerous rip currents at the Jersey
Shore. For Delaware, the flow will be more onshore if not a bit
offshore. As a result, there is a LOW risk for the development
of dangerous rip currents at Delaware Beaches.

Conditions on Saturday will be similar to conditions today,
though Jersey Shore beaches in Monmouth county will have a LOW
risk, while the rest of the Jersey Shore will have a MODERATE
risk for dangerous rip currents. Delaware Beaches will once
again have a LOW risk for the development of dangerous rip
currents.

For specific beach forecasts, visit weather.gov/beach/phi

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch through Saturday afternoon for PAZ070-071-101>106.
NJ...Flood Watch through Saturday afternoon for NJZ001-007>010-012-
     013-015>019.
DE...Flood Watch through Saturday afternoon for DEZ001-002.
MD...Flood Watch through Saturday afternoon for MDZ012-015-019-020.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for
     ANZ450>455.

&&

SYNOPSIS...Wunderlin
NEAR TERM...Staarmann
SHORT TERM...DeSilva/Wunderlin
LONG TERM...DeSilva/Wunderlin
AVIATION...DeSilva/Staarmann/Wunderlin
MARINE...DeSilva/Staarmann/Wunderlin

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
111 PM EDT Fri Jul 12 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1250 PM     Flood            1 S Bayville            39.90N 74.16W
07/12/2024                   Ocean              NJ   Dept of Highways

            Flooding on US 9 both directions CR
            618/Central Pkwy/Butler Blvd (Berkeley Twp)
            All lanes shifted. Time given in report.

&&

Hoeflich

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
158 PM EDT Fri Jul 12 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0130 PM     Rain             1 W Dennisville         39.19N 74.83W
07/12/2024  M3.90 Inch       Cape May           NJ   Trained Spotter

&&

Hoeflich

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
159 PM EDT Fri Jul 12 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0130 PM     Rain             Cape May Court House    39.08N 74.82W
07/12/2024  M4.85 Inch       Cape May           NJ   Trained Spotter

            Storm Total so far.

&&

Hoeflich

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
317 PM EDT Fri Jul 12 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0300 PM     Flood            Woodbine                39.24N 74.82W
07/12/2024                   Cape May           NJ   Broadcast Media

            Pictures of standing water flooding parking
            lots in Woodbine. Time estimated.

&&

Hoeflich