Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kphi 230822 
afdphi

Area forecast discussion
National Weather Service Mount Holly New Jersey
422 am EDT Mon Sep 23 2019

Synopsis...
a cold front will approach today and then move across the
region tonight. High pressure returns for the mid-week period,
followed by another cold front late Thursday and Thursday night.
High pressure builds back into the northeast for the end of the
week into next weekend.

&&



Near term /until 6 PM this evening/...
expect another warm day today as high pressure finally starts
pushing to the east. A surface trough will bring a cold front
through during the late afternoon but not until temp warm up
again into the upper 80s to near 90. When the front swings
through expect showers to move into the Poconos first and then
through the 95 corridor. The best chance for showers will be
along and ahead of the front as we should destabilize briefly
allow for some modest instability. I've kept the idea of some
isolated rumbles of thunder generally from philly northwards.

As for the rest of this morning, patchy fog will likely continue
to build into the favored locations. VAD wind profiles show
modest boundary layer flow so expect the best chance for some
light ground fog near the protected river basins and in more
rural locations. Temps will bottom our in the mid 60s shortly
before warming quickly this morning. As the cape breaks this
afternoon expect it to become fairly breezy with winds gusts up
to 20 mph generally out of the southwest. Winds will be a fair
bit stronger just along the coastline with gusts up to 25-30mph
along the waters. Hope you get to enjoy your day!

&&

Short term /6 PM this evening through 6 am Tuesday/...
overnight Monday should be a fairly pleasant evening. Temps
behind the cold front will drop into the upper 50s to low 60s
and the rainfall will be exiting to the east. Clouds will be
clearing from west to east across the region as high pressure
starts building back across the mid-Atlantic setting up for a
nice week!

&&

Long term /Tuesday through Sunday/...

Tuesday through Wednesday night...

Low pressure with its associated cold front will continue to slowly
move off to the east through Tuesday while high pressure sits across
the Ohio Valley. This will keep the area in a cooler, dry northwest flow
with temperatures a good 10 degrees or so cooler compared to Monday.
Most of the area should see mainly sunny skies but there will be a
fair bit of cu developing across the Poconos into northwest New Jersey. Highs will
be mainly in the 75-80 range except a bit cooler in these northern
areas where it will be in the upper 60s to low 70s.

High pressure drifts east towards the region Tuesday night resulting
in mainly clear skies and light winds. This will allow for good
radiational cooling conditions so lows will be comfortably
cool...generally in the mid to upper 50s with some upper 40s over
the southern Poconos. This will be followed by sunshine, light west
winds and seasonably warm temperatures for Wednesday under dominant
high pressure with highs generally in the 70s to around 80.

By Wednesday night, high pressure moves eastward off the coast with
the flow turning light SW ahead of the next approaching cold front.
This will allow for somewhat warmer overnight lows under continuing
mainly clear skies. Lows will be mainly in the 50s to low 60s,
coolest in the southern Poconos and warmest over the Delmarva NE
through the philly urban area.



Thursday through Sunday...

In the big picture, large scale upper level ridging looks to
continue dominating in the east bringing generally fair weather with
seasonably warm temperatures. That said, there is some uncertainty
in the forecast by next weekend as the GFS brings a cold front
through the area flattening the ridge while the European model (ecmwf) maintains
strong ridging.

To start the period Thursday, a cold front approaches and then moves
through the area late day. However this still looks to be largely a
dry front as most of upper level energy associated with a
progressive upper trough will be to our north. So for this reason,
expect an overall partly to mostly sunny day with highs mainly in
the low to mid 80s along with moderate humidity levels. Exception
will be the southern Poconos where it will be in the 70s.

Cold front quickly sweeps east of the region Thursday night with
high pressure and strong ridging aloft moving back in by Friday.
This will bring more sunshine with seasonably warm temperatures and
low humidity. Beyond this time, as mentioned above, some uncertainty
in the forecast for next weekend. GFS brings a cold front through
from north to south Saturday along with some scattered showers and
then stalls this front near or just south of the area Sunday as high
pressure moves back in from the north. European model (ecmwf) maintains strong ridge
keeping conditions warm and dry. At this point, made little change
from previous forecast and keep conditions mainly dry for next
weekend with highs mainly in the 80s. However if GFS solution ends
up coming to fruition it could be cooler and a little bit unsettled
with a few showers around at times but not a washout.
&&



Aviation /07z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

Rest of tonight...mainly VFR. However, some patchy fog may
develop late. Winds light and variable. Low confidence on fog
formation/timing.

Monday...any fog early in the day will dissipate rapidly.
Mainly VFR with winds increasing from the south/southwest around
10 kt, possibly with some gusts 15-20 kt (especially at
phl/acy). Scattered light rain showers will start to move
through late in the afternoon into the evening as a cold front
moves through. High confidence.



Outlook...

Tuesday and Tuesday night...VFR. Northwest winds 10-15 knots
during the day, then around 5 knots or less overnight.

Wednesday and Wednesday night...VFR. Westerly winds around 5
knots becoming southwesterly less than 5 knots.

Thursday...mostly VFR. Cold front expected to move across the
area during the afternoon, but likely to remain dry for most of
the area except northeast Pennsylvania and northern New Jersey.
Wind shift from southwest to west, then northwest behind the
front and may gust 15-20 knots in the afternoon.

Thursday night...VFR conditions expected. Northwest winds 5-10
knots.

Friday-Friday night...VFR conditions expected. Light and
variable winds early, becoming southerly around knots late in
the day and overnight.

&&

Marine...
south to southwest winds 10 to 20 kt are expected to continue
through Monday with gusts approaching 25 kt by afternoon. Expect
winds to continue into the overnight hours for the Atlantic
waters, with winds expected to be somewhat lower on Delaware
Bay.

In addition, seas will increase to around or slightly above 5
feet by afternoon. As a result, have issued a Small Craft
Advisory beginning at 9 am Monday for the Atlantic waters.

Outlook...

Tuesday...conditions expected to be sub Small Craft Advisory with northwest winds 10-15
knots and seas 3-5 feet.

Wednesday...sub-sca conditions expected with northwest winds around
10 knots turning southwesterly through the afternoon and seas
from 3 to 5 feet.

Thursday...sub-sca conditions expected with southwesterly winds
continuing from 10 to 15 knots and gusts to 20 knots. Seas
building to 2 to 4 feet.

Friday...sub-sca conditions expected with northeasterly winds
from 5 to 10 knots turning easterly by the afternoon. Seas to
sit from 1 to 3 feet.

Rip currents...

There is a high risk for the development of dangerous rip
currents at New Jersey and Delaware beaches on Monday due to
increasing winds and seas. A rip current statement has been
issued for this risk.

&&

Phi watches/warnings/advisories...
PA...none.
New Jersey...high rip current risk from 6 am EDT this morning through this
evening for njz014-024>026.
Delaware...high rip current risk from 6 am EDT this morning through this
evening for dez004.
Maryland...none.
Marine...Small Craft Advisory from 10 am this morning to 6 am EDT
Tuesday for anz450>455.

&&

$$
Synopsis...fitzsimmons
near term...deal

National Weather Service Glossary of Abbreviations