Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Mount Holly New Jersey
1227 PM EDT sun Aug 2 2015

Synopsis...
high pressure extending over the Ohio Valley to middle Atlantic region
will gradually move southeast through Monday. A cold front from the
Great Lakes is forecast to cross our region late Monday into early
Tuesday, eventually stalling just south of our area Wednesday and
Thursday as a wave of low pressure moves along it. This stalled
frontal boundary should remain just south of the Delaware-Maryland-Virginia peninsula
into Friday and Saturday as additional waves of low pressure move
along it.

&&

Near term /until 6 PM this evening/...
no major changes needed to the forecast. Only a few hourly grid
changes and in increase in cloud cover as some cumulus build up
has begun to occur and some cirrus moving northward from the
south. Otherwise, we continue to expect a dry forecast today.

There looks to be a cap right around 700mb this afternoon which
should help to keep US dry today...especially with dewpoints
remaining on the drier side as precipitable waters remain well below normal.
Ample sunshine should allow for another close to if not low-90s
kind of day. Light southwesterly flow should allow for better
seabreeze inland penetration and possibly Bay/River Breeze close
to ilg/phl.

&&

Short term /6 PM this evening through 6 am Monday/...
another mostly clear night is expected with high pressure continuing
to pass overhead and out to sea late tonight. Weak low-level
moisture advection commences with light southerly winds in
place...dewpoints remain on the drier side north of Delaware-Maryland-Virginia late
tonight. Could be some pockets of ground fog across southern New
Jersey and Delaware-Maryland-Virginia late tonight. Temperatures dip back into the low
to middle-60s with good radiational cooling conditions expected.

&&

Long term /Monday through Saturday/...
a more active, unsettled pattern is expected through much of the
long term period. A cold front will approach our region from the
northwest, around the Great Lakes, during Monday. The cold front is
prognosticated to gradually pass through the region from late Monday into
early Tuesday. While timing and coverage of shower/tstorm activity
associated with this boundary and some shortwave energy aloft still
remains a little uncertain, it does appear that a few stronger
storms with gusty winds are possible as there is adequate modeled
cape and shear. Into Tuesday, the cold front is prognosticated to be
passing south and east of our area, eventually stalling offshore.
While overall coverage of any pop-up showers/thunderstorms looks to be low,
some slight chance probability of precipitation have been kept as some model guidance shows
another possible shortwave aloft perhaps moving over the region
later in the day.

This overall pattern looks to continue through Wednesday and
Thursday, and also into the Friday/Saturday timeframe, with the
stalled frontal boundary remaining near or just south of the
Delaware-Maryland-Virginia. Timing and coverage of shower/tstorm activity remains highly
uncertain at this extended range, and while a complete washout is
not likely in the middle to late week period, both the GFS and European model (ecmwf)
show the potential for a wave of low pressure to develop and move
along the stalled boundary in the Thursday timeframe and also
possibly for Friday into Saturday. We therefore have focused some
higher chance probability of precipitation for the area on Thursday. Otherwise with the
continued uncertainty through this extended range, we mostly used a
blend of wpc guidance with continuity for temperatures, pops, and
winds.

&&

Aviation /18z Sunday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

Today...VFR. Light and variable winds to start the today before they
pick more of a southwesterly direction. Should see seabreeze and Bay
breeze circulations affect Acy and ilg for a time this afternoon.

Tonight...VFR. Winds back more towards the south late this evening
but decrease becoming light and variable once again with high
pressure overhead.

Outlook...
Monday...possible patchy MVFR conditions in fog early, mainly at the
more rural terminals. Then primarily VFR conditions through the day,
but a lowering to MVFR with ceiling/visibility restrictions in scattered
showers/thunderstorms from late-day into the night.

Tuesday...mostly VFR conditions. Isolated to perhaps scattered
showers/thunderstorms are possible.

Wednesday...mainly VFR conditions.

Thursday...MVFR conditions possible during showers and thunderstorms.

&&

Marine...
sub-Small Craft Advisory conditions expected today and tonight. Seas remain around 3
feet as winds slacken this afternoon and remain primarily offshore.
High pressure overhead tonight will allow for even more tranquil
conditions to set in.

Outlook...
Monday and Tuesday...conditions may approach Small Craft Advisory criteria. Some wind
gusts could be around 25 knots plus with seas increasing for the
coastal waters late Monday into early Tuesday associated with a cold
front passage.

Wednesday and Thursday...mostly sub-Small Craft Advisory conditions; however, a
stalled front and a wave of low pressure moving along it could
enhance seas and/or winds for the coastal waters, especially into
Thursday.

&&

Phi watches/warnings/advisories...
PA...none.
New Jersey...none.
Delaware...none.
Maryland...none.
Marine...none.

&&

$$
Synopsis...gigi/Kline
near term...Heavener/Robertson
short term...Heavener
long term...Kline
aviation...Heavener/Kline
marine...Heavener/Kline

National Weather Service Glossary of Abbreviations