Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
408 am EDT Monday may 25 2015
high pressure will be anchored off the East Coast this week. A
warm front will move northward through our middle-Atlantic region
today. A cold front will approach from the west Wednesday and
eventually dissipate as it moves through the forecast area
Thursday. Another cold front is forecast to pass through this
Near term /until 6 PM this evening/...
airmass continues to modify today with an increase in low-level
temperatures expected with a weak warm frontal passage to our
north this afternoon. Most, if not all, of the energy and lift
with the front will remain to our north. Even with moisture
streaming into the region the lack of lift and subsidence aloft,
as ridging remains entrenched to our southeast, will keep our
We should be able to mix upwards of 850mb, if not higher, this
afternoon keeping our dewpoints in check with widespread wind gusts
upwards of 25 miles per hour this afternoon. Todays stronger southwesterly
flow, behind the frontal passage, and being fully within the warm
sector a very warm day is expected. Even though 850mb temperatures
may not completely support upper-80s for highs today, given the
amount of sunshine expected and the very dry ground in place, we
should have some home cooking and add a couple degrees on the stat
Short term /6 PM this evening through 6 am Tuesday/...
not much change from the previous couple of nights, just a warmer
starting point and more moisture surging into the region. We do
not completely decouple so we continue with some boundary layer
mixing, though not much in the way of gusts. The added mixing will
keep temperatures well above normal for the overnight period with
lows only dropping into the low to mid-60s...slightly cooler in
The Pine Barrens and along the coast. We continue with a dry
Long term /Tuesday through Sunday/...
high pressure will remain anchored over the western Atlantic Ocean
this week and even into next weekend. Deep southerly return flow
around the offshore high will yield a Summer-like pattern with above
normal temperatures, increasing humidity and a seemingly daily
chance of showers and storms through much of the long-term period.
Both the heat and humidity will be factor on Wednesday when heat
indices may reach 90-92f in the urban corridor.
Convective initiation on Tuesday will be favored over the higher
elevations. Since terrain circulations appear to be primary lifting
mechanism for showers and storms and large-scale subsidence will be
stronger farther eastward as you get closer to the upper ridge that
is just offshore, convection will mainly be confined to NE PA and northwest
New Jersey during the afternoon.
Chances for showers and storms increase Wednesday and Thursday as
troughing develops over the Great Lakes and northeast states. Nwp
guidance shows several shortwave troughs moving through the forecast
area which would provide the required lift for more organized
convection. An cold front is expected to dissipate as it moves
through the forecast area. Depending on how quickly it washes out,
it may provide additional focus for convection Thursday afternoon
and night. The highest probability of precipitation generally reside west of I-95 both days,
where models show a corridor of greater instability and lift.
Upper ridging is expected to develop over the eastern Seaboard
Friday in wake of thursday's trough. The 00z GFS/Canadian/ECMWF
models all show a piece of energy associated with the aforementioned
trough's pv tail hanging back underneath the ridge. It may keep
clouds around and provide lift for additional showers and storms
Friday if it does become trapped underneath ridge. This feature is
rather subtle with inherently limited predictability this far out.
A low pressure system is forecast to move eastward through eastern
Canada next weekend. The cold front associated with this system may
approach the area during this time. There is still uncertainty with
the timing of the fropa, but it will enhance the chances for showers
Aviation /08z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
Today - tonight...VFR. Southerly winds increase later this morning
and veer towards the west of south by the afternoon hours. Expecting
gusts into the low-20 knots range to occur today. Not sure a true
east-southeast seabreeze makes its way Acy with the stronger winds
expected this afternoon. By later this evening the gusts begin to
drop off but we keep winds 8-10 knots through the overnight
Tuesday through Friday...patchy radiational fog is possible in the
early morning each day. Isolated showers and storms near ridge/Abe
Tuesday afternoon. Daily chances for showers and storms expand to
all terminals Wednesday through Friday. Coverage of convection will
likely be highest on Thursday.
today and tonight...small craft for the northern half of our
waters GOES into effect this afternoon as stronger southerly winds
commence. Frequent 25 to 30 knots gusts expected through the
overnight time period before subsiding towards daybreak on
Tuesday. Seas will ramp up towards 5 feet across the northern
waters under the increasing southerly fetch.
Tuesday and Wednesday...southerly winds will gust 20-25 knots during
the afternoon hours each day, especially along the coast as the
deepest mixing will occur on land. Confidence for 25 knots gusts not
high enough to extent the current Small Craft Advisory into Tuesday. Seas may also
approach 5 feet Tuesday night through Wednesday night.
Thursday and Friday...winds and waves will be below Small Craft Advisory threshold.
Marine...Small Craft Advisory from 2 PM this afternoon to 6 am EDT
Tuesday for anz450>452.