Scientific Forecaster Discussion
fxus61 kphi 290135
Area forecast discussion
National Weather Service Mount Holly New Jersey
935 PM EDT sun may 28 2017
a low pressure system stalls over Ontario tomorrow. Two cold
fronts associated with this low are expected to move through our
region, one on Monday, and another late Tuesday or early
Wednesday. High pressure will build in over the region on
Thursday. Another low pressure system is expected to approach
the region Saturday.
Near term /until 6 am Monday morning/...
showers continue to move across the region this evening. While a
small chance exists for a rumble of thunder, in general, most
areas will see light showers through tonight.
Clouds will remain across the area all night, so low temperatures
will not be that cool. Readings will only fall into the upper
50s (north) and low 60s elsewhere.
Short term /6 am Monday morning through 6 PM Monday/...
Monday, Memorial Day, looks to feature cloudy conditions across the
area with some improvement later in the day. Showers will be across
the North/East areas during the morning, but these will move away by
afternoon. Temperatures will be cool early, but then jump once the
clouds begin to thin. High temperatures will range from the low 70s
north to the low 80s over Delmarva. Winds will switch from
onshore...to wrly at 5 to 10 knots.
There is a growing chance that the cloud cover remains thicker
across the region, especially across the northern areas. As a
result, high temperatures may not break out of the lower 60s through
northern New Jersey and the Poconos.
Long term /Monday night through Sunday/...
the main thing to watch through the long term period will be the mid
and upper level low that is expected to mostly stall out over
Ontario early this week.
Monday night...added fog to the forecast...areas along the coast
and patchy inland. It clears aloft, though some cirrus at times.
That leaves mondays stratus deck likely to settle to the sfc as
fog...possibly dense in a light wind field with the weak sfc
Tuesday and Wednesday...a secondary cold front (the first one, a
rather weak and dissipating one is expected tomorrow) is expected to
move through the region either late Tuesday or early Wednesday at
the same time a mid level short wave trough digs along the south
side of the main low. Synoptic scale lift isn't especially
impressive through this time period, but there could be enough
instability both days to support some thunderstorms. Despite the
cold front, temperatures through this period should stay near or
even slightly above normal, with highs generally in the 70s and 80s.
Thursday...with a surface high building over the region, this looks
to be the day with the best chance of dry weather of the week. It
also looks like the coolest day of the work week, with temperatures
slightly below normal.
Friday through Sunday...as mentioned by the previous shift, the
details in this period are uncertain at this time as it will be
highly dependent on how the mid and upper level low evolves. At this
point, there are rather large differences both between models and
with run to run consistency. Therefore, stayed close to the previous
forecast and a guidance consensus through this period.
Aviation /02z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
VFR conditions remain at most of the terminals with MVFR at
kacy and kmiv. Expect conditions to deteriorate through the rest
of the night as rain spreads across the terminals. Ceilings will
drop further to IFR through the overnight period.
Scattered showers will remain across the terminals through much
of the night, which will help to keep low clouds/fog in place
through much of the taf period. A small chance for thunder
exists overnight but confidence is too low to include in the
tafs at this time.
Winds will be mostly out of the east to southeast around 5 to
10 knots tonight.
Skies are expected to lift a little on Monday but remain
IFR/MVFR into the afternoon. Some improvement might occur into
Monday evening but confidence is low.
Tuesday and Wednesday...some possible fog or low clouds to
start Tuesday, otherwise generally VFR through Wednesday. There
is a chance for showers and thunderstorms each day which could
also lead to conditions below VFR.
Thursday...VFR is anticipated with dry conditions.
Friday...increasing shower and thunderstorm chances. If any affect
the taf sites, it may result in MVFR or lower conditions.
we will continue with the Small Craft Advisory flag for the northern New Jersey coastal
waters as previously outlined. While conditions have been sub-Small Craft Advisory
today, a gradual increase in seas is expected overnight with the
continuing southeast flow across the waters. Scattered showers are expected
overnight. There is a chance for a thunderstorm too, mainly across
Delaware Bay and possibly the Delaware ocean waters.
Tuesday through Friday...winds and seas are expected to stay below
Small Craft Advisory criteria. However, seas may begin to build above 4 ft on Friday.
The outlook for Monday is still a low risk for the development
of dangerous rip currents. A 2-3 foot east or southeast swell
and a south or southwest wind is expected to develop from
southern New Jersey southward (atlantic and Cape May counties in New Jersey and
Sussex County de).
A somewhat enhanced but still low risk for the formation of
dangerous rip currents may develop for Monmouth County and possibly
the beaches of northern Ocean County New Jersey where an east or northeast
wind of 15 mph may persist through the entire day.
onshore flow continuing into the evening hours and the
continued high astronomical tides should result in another round
of minor coastal flooding tonight. As a result, the coastal
flood advisory continues for the high tide cycle tonight. It
covers the coastal counties of New Jersey and Delaware, as well
as the counties along Delaware Bay and the lower Delaware River
up to the area just below the Commodore Barry bridge.
Based on the guidance and on the fact that the astronomical
tides are decreasing as we move away from the new moon,
tonight's coastal flood advisory should be the last one for a
may rainfall as 2 PM today:
Acy 7.11 inches ranked #2. Record 8.80 1948. Por 1874.
Phl 6.12 inches. Ranked #11 record 9.46 1894. Por 1872. #10 is
6.65" just last year.
Ilg 5.70 inches. Ranked #16. Record 11.99 1894. Por 1894.
May rainfall in central Delaware without todays amts...ie through the 27th
Dover 6.03 and 6.50 (two different deos reported sites)
New Jersey...coastal flood advisory until 3 am EDT Monday for njz012>014-
Coastal flood advisory until 4 am EDT Monday for njz016.
Delaware...coastal flood advisory until 3 am EDT Monday for dez002>004.
Coastal flood advisory until 4 am EDT Monday for dez001.
Marine...Small Craft Advisory until noon EDT Monday for anz450>452.