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FXUS61 KPHI 201012

Area Forecast Discussion
National Weather Service Mount Holly NJ
612 AM EDT Sat Jul 20 2019

A strong ridge of high pressure will remain in place through 
the weekend across the eastern US. A few disturbances will pass 
to our north late tonight and Sunday night. By Monday, a 
seasonably strong cold front will begin approaching the Mid- 
Atlantic region from the northwest which will push south of the 
area by late Tuesday. Much cooler and drier weather will be left
in its wake through the end of the work week with cool high 
pressure settling in across the Midwest.


The Excessive Heat Warning remains in effect for all of eastern
Pennsylvania, northeastern Maryland, Delaware and New Jersey. 
We are anticipating highs mainly in the middle and upper 90s. 
Readings in the elevated terrain of the Poconos and far northern
New Jersey should peak around 90 degrees. The same is true 
right along the immediate coast. Dew points are expected to 
favor the middle 70s for today. As a result, where temperatures 
reach the middle and upper 90s, maximum heat index values are 
forecast to range from about 107 to 112.

The wind is forecast to be from the southwest around 5 to 10 

We are not expecting any precipitation in our region for today.
A substantial mid level cap should prevent any convection from 
developing although there will likely be scattered cumulus from 
late this morning into this afternoon. Also, there will be some 
cirrus debris clouds overhead at times from the convection to 
our northwest.


Another warm and muggy night is expected. We should continue to
see occasional patches of high clouds associated with 
additional convection to our northwest. The precipitation is not
expected to reach our forecast area tonight.

Low temperatures will range from the middle 70s to the lower 
80s with a light southwest wind.


A rather significant shift in the sensible weather is in store 
for much of the region throughout the long term period.

The ongoing heat wave will continue into Sunday with rather 
extreme heat indicies area wide. Air temperatures are forecast 
to be well into the mid to upper 90s outside of the highest 
terrain and away from the immediate coast with dewpoints in the 
mid to upper 70s. Resulting heat index values are forecast to 
range from 110-115 across most of central and southern NJ, SE 
PA, and Delmarva away from the immediate coast. Across the 
Lehigh Valley, NW NJ, and immediate coastal areas, widespread 
values of 105-110 can be expected. Values from 95-100 are 
expected across the southern Poconos. Otherwise, it should be a 
mostly sunny but hazy day. A disturbance passing north of the 
area Sunday night may lead to some scattered showers or 
thunderstorms from late evening to overnight. Cannot rule out an
isolated strong to severe storm with this activity as 
instability will remain high even into the overnight hours.

Moving into Monday, an upper level trough will begin digging 
south across the Great Lakes weakening the strong upper ridge 
and finally giving us a break from the heat. Dewpoints are 
likely to remain high (mid 70s) ahead of the front, however 
temperatures will be about 10- 12 degrees cooler on Monday. With
the approaching trough, several shortwaves will cross the 
region ahead of the approaching cold front throughout the day 
and into the overnight hours. As a result, expect to see 
multiple rounds of showers and thunderstorms on Monday into 
Monday night. Heavy rain will be the main threat, however there 
will also be a severe weather threat given enough instability 
and vertical wind shear. Details on this are yet to be seen and 
will come into better focus within the next few forecast cycles.

By early Tuesday, the cold front will finally start to make its
way toward the forecast area before moving offshore by late in 
the day. With its passage, extensive cloud cover and more 
showers and thunderstorms can be expected. The severe weather 
threat appears to be low on Tuesday, however heavy rain is 
certainly still possible. The showers will end with the passage 
of the front, which is still uncertain at this time. 
Temperatures Tuesday are forecast to be below normal and the 
humidity will lessen significantly after the front passes.

By Wednesday, relatively cool and dry high pressure will be 
settling across the Midwest. This high pressure is forecast to 
eventually pass across the Mid-Atlantic by Friday before moving 
offshore into next weekend. Temperatures will start out a few 
degrees below normal on Wednesday then rebound to near normal 
values by the end of the week and into next weekend. Cannot rule
out and isolated shower or storm Thursday and Friday, but 
overall everywhere looks dry through the end of the week. Better
chances of showers and storms will return next weekend.


The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, 
KILG, KMIV, KACY and surrounding areas.

Today...VFR with scattered clouds. Southwest wind 5 to 10 

Tonight...Mainly VFR. Southwest wind 6 knots or less.


Sunday...VFR expected. Hazy skies may limit visibility in some 
areas. Isolated thunderstorms possible during the late 
afternoon. West winds around 5-10 kts.

Sunday night...isolated to scattered showers and thunderstorms 
expected during the evening and overnight. Sub-VFR possible. 
Light and variable winds.

Monday through Tuesday night...Widespread heavy showers and 
thunderstorms expected. MVFR likely with IFR possible. West to 
southwest winds around 5 kts.

Tuesday night through Wednesday night...VFR expected. Northwest
wind around 5 kts or less.


The wind should favor the south and southwest around 10 knots 
for today and tonight.

Wave heights on our ocean waters are expected to be 2 to 3 
feet. Waves on Delaware Bay will likely be 2 feet or less.


Sub-SCA criteria expected through the outlook period. Winds and
seas will likely build Monday and Tuesday with heavy showers 
and thunderstorms expected, but sub-SCA conditions will still 


A southerly wind around 10 MPH is expected for today along the 
coasts of Delaware and New Jersey. Breaking waves around 2 feet 
are anticipated along with a medium period southerly swell. As a
result, there should be a low risk for the development of 
dangerous rip currents for today.

Wave/rip current conditions on Sunday are expected to be 
similar to those of today along the coasts of New Jersey and 

It appears as though there is some upwelling along the New 
Jersey coast, mainly from Long Beach Island down to the Atlantic
City area. Water temperatures right along the shore are in the 
middle and upper 60s in spots.


Record Maximum Temperatures for:

Site    High/Year            Low/Year
ABE      101/1980             76/1942
ACY       97/1991             79/2015
PHL       99/1930             81/2015
ILG      100/1895             79/2015
RDG      100/1980             77/1942
TTN       99/1980             78/2015
MPO       93/1980             69/1988
GED      100/1977             81/2013

Site    High/Year            Low/Year
ABE      101/1980             75/1980
ACY       99/1981             77/1991
PHL      103/1930             79/2017
ILG      102/1957             77/1972
RDG      102/2011             77/2011
TTN      101/1930             78/1980
MPO       94/2011             72/2011
GED      101/1957             79/2017


PA...Excessive Heat Warning until 10 PM EDT Sunday for PAZ054-055-
NJ...Excessive Heat Warning until 10 PM EDT Sunday for NJZ001-
DE...Excessive Heat Warning until 10 PM EDT Sunday for DEZ001>004.
MD...Excessive Heat Warning until 10 PM EDT Sunday for MDZ008-012-



Near Term...Iovino

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