Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 300058
Area Forecast Discussion
National Weather Service Mount Holly NJ
858 PM EDT Sat Apr 29 2017
A cold front across the Delmarva will slide south then stall
before returning northward into our area as a warm front Sunday
night. Low pressure and its associated fronts move toward the
Middle Atlantic states later Monday and Monday night. High
pressure will build in for the middle of next week. Another low
will affect our area towards the end of next week.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
930 PM ESTF: expecting the sfc convergence to increase during
the night in the high PWAT air along the front across the
Delmarva and expect showers to develop, possibly heavy with
maybe isolated thunder.
Otherwise, a wind shift to the north and northeast will move
from north to south overnight as part two of the cold front
works southward. Low temperatures were mostly a MOS/continuity
blend and the downward trend was delayed a little.
Max temps for ACY PHL Sunday may be occuring at 1 am.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
The 630 PM Saturday update added chance of sprinkles to much of
the area Sunday morning and the 930 PM raised pops slightly and
called it isolated showers or scattered sprinkles. The
reasoning...some of the models are producing qpf and while there
is a generally ely bl flow, there is waa above the inversion
(above 900mb) and small sign of a lobe of instability moving
newd during the morning that also gives a deep vertical 2 hr
wide spike in rh. I wanted to put the uncertainty of a shower in
the fcst for Sunday morning.
The weather will be rather different Sunday compared to today
(Saturday) in the wake of a cold front. This front is expected
to clear our entire area before stalling in a west to east
orientation. An upper-level ridge axis should be moving across
our area, allowing surface high pressure to build to our north
and east. This will allow for a northeast low-level flow which
should become east and then southeast with time. This will allow
for a much cooler airmass to be over our area, enhanced by the
flow off the colder ocean waters.
While there may be areas of stratocumulus, the cloud bases may lower
especially in the afternoon as the flow turns more east and
southeast resulting in some increase in the moisture. Overall
though, there should be a fair amount of cloudiness across the
region during the day.
High temperatures were a MOS/continuity blend, then some tweaks were
made mostly along the coast.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
A weak ridge of high pressure will be across the area during the
start of the long range. It will remain in place through Monday
before moving to the east. Dry weather is expected Sunday night,
then clouds will increase Monday along with the chances for a few
showers across the N/W areas Monday afternoon. Temperatures will be
above normal with highs Monday in the low 80s over srn NJ and
Delmarva while highs will be in the mid/upper 70s across the N/W
A low pressure system across the upper Great Lakes Monday morning
will move NE across southern Canada through Wednesday. A strong cold
front will move across the Middle Atlantic Mon night and into early
Tue. There appears to be a decent chc for showers and tstms with
this front, so only small changes to the already high pops were made
today. We have categorical pops N/W and high Likely S/E. It could be
a 1/4 to 1/2 inch rain producer, higher in tstms. On Tuesday, the
front will be east of the area, but the lingering upper low aloft
will lead us to keep the chc for some showers into the early
afternoon. High temps Tue will still be a little above normal S/E
but by Wed, readings will be close to normal for early May.
A short period for far weather Wed/Wed night with an area of high
pressure across the area. Another low will approach Thu and will
again bring decent chc for showers and sct tstms (Delmarva) for the
end of next week. We have some likely pops for many areas Thu/Thu
night and chc pops for Fri/Sat. Temperatures will be near or
below normal towards the end of the week.
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Tonight...VFR with a few clouds near 5000 feet and cirrus on top.
A broken deck of clouds near 5000 ft will form...develop newd
into the TAF sites toward 09z/30 and there may be a few showers
vcnty KILG. Winds northwest then shifting northeast after 06z/30.
Gusts generally under 18 kt. Please see TAFS for the details.
Sunday...VFR ceilings may lower to MVFR through the day, however
confidence is below avg on timing any lowering to MVFR CIGS.
Chance of a morning sprinkle or shower (waa- elevated instability)
Northeast winds around 10 knots, becoming east and southeast in
Sunday night-Monday morning...IFR conds in st/fog and possible
drizzle in light moist maritime easterly flow north of a
Mon Afternoon...Mostly VFR expected.
Mon night thru Tue...Restrictions with showers especially Mon
Tue night thru Wed night...Mostly VFR. Patchy morning fog
Thu...Restrictions possible with showers.
A cold front has sort of stalled from the vicinity of Cape May
NJ westward to the northern part of Chesapeake Bay, there will
be a reinforcing of the front from the northeast toward 12z and
hat will force it further to the southwest during the day Sunday.
There could be a northeast to east wind surge Sunday especially
across the northern coastal waters zones, however for now, gusts
are below 25 knots. The duration of this does not look long
enough and therefore kept seas 4 feet or less.
Sun night thru Mon morning...Sub-SCA conditions with Patchy fog
and possibly some drizzle.
Monday afternoon thru Tue night...SCA expected. Showers with
Tue night...SCA on the ocean and sub-SCA across Del Bay. Fair.
Wed thru Thu...Sub-SCA. Fair thru Wed night then sct showers
RER for the new record high temperature at Georgetown, DE...91
at 241PM was issued. Atlantic City was 1 shy (91). Atlantic
City doesn`t normally reach 90 until June 11 although the long
term statistical database may be skewed to cooler temperatures
closer to the coast. The earliest 90 degree day at Atlantic City
occurred April 7, 2010.
**Record or number 2 warmest April on record**
Presuming our forecast temps these last 30 hrs of April are
accurate, we are assured of a top 2 warmest April on record in
much of our forecast area. Sunday temps determine record or
Just Below: April projected within the top April average temps,
the normal for April and the period of record (POR).
This includes todays (29th) high and low temperatures through 4
Sundays max temps may occur at 1 am and the min temps Sunday
PHL normal 54.0 POR 1874
59.5 2017 Projected warmest ever: still could slip .2 degrees.
ABE normal 49.9 POR 1922
56.8 projecting record and almost cant miss a record.
ACY normal 51.7 POR 1874
57.6 projecting record and almost cant miss.
We are aware of the DOV dewpoints being excessively high the
past two days and even far too high this evening.
Near Term...Drag 859
Short Term...Drag 859