Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 241913

Area Forecast Discussion
National Weather Service Mount Holly NJ
313 PM EDT Mon Oct 24 2016

High pressure near Hudson Bay Canada will build closer to our region
through mid week. A warm front on Thursday will be followed by a
cold front Thursday night as low pressure redevelops from near Lake
Erie Thursday to Long Island Friday morning. Weak high pressure
quickly follows Friday night before low pressure and its associated
frontal systems cross the mid Atlantic states Saturday. High
pressure will become dominant over our area by next Monday.


A relatively quiet night expected tonight across the area. Partly to
mostly cloudy skies late this afternoon and early evening will
become mostly clear later this evening overnight. Clouds may begin
increasing across the northern areas as we approach daybreak
Tuesday. Also, with these advancing clouds, it is possible for some
sprinkles or flurries to occur across our far northern areas as some
enhanced moisture/lift moves into the area within the northwest
flow. Any precipitation amounts are expected to be light.

Winds will remain gusty for the late afternoon hours, diminishing
some around sunset and through the evening. With an area of low
pressure well to our north and high pressure well to our northwest,
we continue to keep a tight pressure gradient across the area. This
will keep a steady flow across the area through tonight with winds
generally 5-10 mph overnight, even once the gusts drop off.

Temperatures will cool significantly tonight compared to last night
with widespread 30s, and some 40s. However, with the expected wind
and possible increase in clouds late, we do are not expecting
widespread frost, so we do not anticipate a frost advisory for
tonight/Tuesday morning at this time.


There could continue to be some sprinkles/flurries at the start of
the day Tuesday due to the enhanced moisture/lift across the area
within the northwest flow. Any precipitation should dissipate
through the morning, however, clouds cover should expand and
increase in coverage across the area during the day.

Winds will again become gusty through the day with gusts reaching 25-
30 mph at times across the area. With the winds, it will feel much
cooler than the actual air temperature with is expected to be mostly
in the 50s, with 40s across the far northern areas.



*Long Term will be updated by 4 pm.*

Tuesday...Cold air advection pattern continues with Tuesday night
likely being the coldest night of the season so far for many
locations. Highs on Tuesday are expected to be 5 to 15 degrees
below normal. For Tuesday night, current forecast lows in the
Lehigh Valley, Pine Barrens and the remainder NW NJ (areas that
have not yet had a freeze) are right around freezing (31 to 33).
At the very least, it looks likely that these areas will see frost
and could see a freeze. The Philly metro and Delmarva should be
a bit warmer, but could also see patchy frost.

Wedensday...Cold air advection continues for one more day, so
expect highs on Wednesday to be a few degrees lower than Tuesday.

Wednesday night through Thursday night...Most of the other
deterministic models have come into closer agreement with the more
progressive timing of the GFS. The good news with this solution is
that cloud cover should increase rather early on Wednesday night,
limiting radiational cooling (and also consequently making frost
unlikely). The bad news is that even so, precip arriving ahead of
the surface warm front due to warm air advection aloft and a mid
level short wave trough, could be a wintry mix across the southern
Poconos and NW NJ. Current model soundings of the GFS indicate a
warm layer from just above the surface through 7000 or 8000 ft
AGL. This would suggest more of a rain or freezing rain situation.
However, previous model runs depicted more of a rain/snow mix, so
for now will continue with that in the forecast, and continue to
mention potential for icy spots in these areas on Thursday

In addition to the earlier arrival of the precip, the dry slot and
surface cold front is also now expected to arrive earlier in our
region, leading to precip ending quickly on Thursday night if this
timing holds true.

Friday...a short wave ridge slides over the region through the
day, leading to quickly clearing skies and limiting the period of
cold air advection.

Saturday and Sunday...models are depicting another low pressure
system sliding over or just north of the region. As such, chances
for precip through this time period have increased from previous
forecasts. For now have stayed close to a blend of model guidance
until there is better run to run consistency.


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

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

VFR conditions will continue through the TAF period. The scattered
to broken stratocumulus clouds around 4,000-6,000 feet this
afternoon will dissipate this evening and overnight with the loss of
daytime heating; although there could still a few lingering clouds
around overnight.

The main concern is the gusty winds today and again Tuesday.
Northwest Winds will continue to gust around 25-30 knots this
afternoon. The gusts will diminish some around sunset to around 15-
20 knots, with the gusts expected to drop off overnight. The gusts
will return Tuesday with gusts 20-25 knots again, with some locally
higher gusts 25-30 knots possible.


*Outlook will be updated by 4 pm.*

Tuesday and Wednesday...Mostly VFR conditions expected.

Wednesday night and Thursday...ceilings will lower to MVFR (with
localized IFR) by day break Thursday. Visibility restrictions
possible with rain showers Thursday into Thursday evening.

Friday...Ceilings should return to VFR early in the day.


Small craft advisory remains in place for tonight and has been
extended into Tuesday as winds are expected to continue to gust
25- 30 knots across the waters tonight into Tuesday. Wind gusts on
the Delaware Bay may drop below 25 knots overnight, but are
expected on increase again on Tuesday.


*Outlook will be updated by 4 pm.*

Tuesday...On the coastal waters could have gusts right around 25
kt, but confidence is low at this time.

Wednesday...winds and seas should stay below SCA criteria through
the day time hours.

Thursday and Friday...winds are expected to build through the day
on Thursday and could be near SCA criteria on the coastal waters.


PA...Freeze Watch from late Tuesday night through Wednesday morning
     for PAZ060>062-101>103-105.
NJ...Freeze Watch from late Tuesday night through Wednesday morning
     for NJZ008>010-012-013-019>022-027.
DE...Freeze Watch from late Tuesday night through Wednesday morning
     for DEZ001.
MD...Freeze Watch from late Tuesday night through Wednesday morning
     for MDZ008.
MARINE...Small Craft Advisory until 11 PM EDT Tuesday for
     ANZ430-431- 450>455.



Near Term...Robertson
Short Term...Robertson
Long Term...Johnson
Marine...Franck/Johnson/Robertson is the U.S. government's official web portal to all federal, state and local government web resources and services.