Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
636 am EST Monday Nov 30 2015
high pressure over northern New England this morning will shift
eastward into the Gulf of Maine this afternoon and tonight. A warm
front will approach from the south on Tuesday before lifting
northward into our area Tuesday night. Meanwhile, low pressure is
expected to track eastward across the upper Midwest and Great Lakes
regions Tuesday into Wednesday. A cold front will move through the
Middle-Atlantic States late Wednesday. High pressure builds in from the
west late in the week and settles overhead this weekend.
Near term /until 6 PM this evening/...
high pressure across southeastern Canada will push eastward today
and off the northern New England coast. The return flow around the
high will allow winds to become more easterly through the day,
ushering in more moisture and in turn more clouds.
With the increased moisture and onshore flow, we will start to see
some showers make their way into our area. Rain is expected mainly
across our southern areas through this afternoon, associated with a
shortwave moving across the region.
Temperatures today will range from upper 30s/lower 40s across the
northern zones to low to maybe middle 50s across the southern zones.
Short term /6 PM this evening through 6 am Tuesday/...
the frontal boundary off to our south will start to push northward
tonight as a warm front. As the front approaches the region, we will
see an overspreading of thicker clouds and rain will push northward
into our area. Rain will gradually spread northward through the
Areas across the far north may remain less cloudy to start the
night but they will eventually cloud up just like the rest of the
area. Depending on how fast the skies cloud up, we may see some
decent radiational cooling take place and this may cause
temperatures to fall below the freezing mark for a period of time
tonight. Should this occur and the precipitation reach these areas
before thicker cloud cover and warming occurs, we may see a period
of light freezing rain or freezing drizzle in the Poconos and
extreme northwest New Jersey. The models are not gung-Ho on the
freezing precipitation scenario as they show the warm air
advection taking over fairly quickly. We will continue a mention
of rain with a slight chance of some freezing rain across the
far northern zones for tonight.
Temperatures tonight will largely remain in the middle/upper 30s to middle
40s. Northern areas may drop down into the upper 20s/lower 30s
before skies really cloud up.
Long term /Tuesday through Sunday/...
a vertically-stacked low over the upper Midwest on Tuesday is
forecast to weaken and eventually become an open wave as it
progresses eastward into the Great Lakes Tuesday night and
Wednesday. Downstream of this system, deep southerly flow up the eastern
Seaboard will cause the frontal boundary that is currently over
the Carolinas to lift back northward through the middle-Atlantic region
on Tuesday. The front should eventually move into the forecast
area as early as Tuesday afternoon but more likely Tuesday night.
We'll most likely have a round of steady light to perhaps locally
moderate rain prior to the arrival of the warm front Tuesday
morning in southern zones and Tuesday afternoon in northern zones (when
low- level isentropic lift is maximized in the cool sector
to the north of the front). There will likely be a lull in the
precipitation late Tuesday once the warm front moves through.
The models continue to trend wetter for Wednesday. In particular,
the 00z NAM and GFS show Lee cyclogenesis on the east side of the
southern/central Appalachians. In these solutions, the wave of low
pressure tracks northeastward along the front and moves through the northern Middle-
Atlantic States on Wednesday. This would slow down the downstream
progress of the front until the low passes to our north and
enhance rainfall over our area. Event total rainfall amounts from
the NAM and GFS are over two inches with over half of it occurring
on Wednesday. Quantitative precipitation forecast amounts from the 00z European model (ecmwf) and Gem are about
half of the NCEP models. These lower totals are likely tied to the
models having a weaker secondary low cut to our west.
Given the latest model trends, clearing in wake of frontal passage may be
delayed in the coastal plain until Wednesday evening. If the low
deepens rapidly enough off the New England coast as indicated by the
00z GFS, the pressure gradient could produce a breezy west-northwesterly winds
late Wednesday night into part of Thursday, especially with
steeper lapse rates supporting the ability for stronger gusts
aloft to mix down to the surface.
Expect a quiet stretch of weather days 4-7 of the forecast with high
pressure building in from the west late in the week and settling
overhead next weekend.
Temperatures in the long term will start off 5-10f degrees above normal
ahead of a cold front Tuesday and Wednesday (could have been even
warmer if it wasn't for the clouds and rain) and near normal
behind the front Thursday through Sunday.
Aviation /12z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
Today... mainly VFR conditions expected with a trend towards MVFR
later today. The model guidance continues to show disparity when it
comes to how fast the lower clouds and precipitations will arrive at
the terminals. Preference remains with the NAM at this time as the
soundings are more indicative of a more progressive solution.
Ceilings will drop to MVFR as the easterly flow increases moisture
in the lower levels.
Tonight...VFR conditions may continue early, especially north and
west of kphl with deteriorating conditions expected as rain expands
northward across the region. MVFR/IFR conditions to develop at
terminals from south to north as a warm front moves northward into
Easterly winds will continue across the terminals, generally
remaining around 10 knots or less.
Tuesday and Tuesday night...periods of MVFR and IFR in low clouds
and rain. Widespread rain may be moderate at times during the day.
Rain could potentially taper off briefly at night but not much
improvement in the ceilings are likely. Light Ely winds become southerly at
Wednesday...MVFR and IFR conditions. Showers may be moderate to
heavy at times ahead of a cold front. Light S-southwesterly in the morning
become westerly in the afternoon. Conditions may start to improve toward the
end of the day out toward rdg/Abe. Uncertainties in the timing of
the front make this a lower confidence forecast.
Wednesday night...MVFR may linger early in the night, especially
near the coast. Conditions eventually improve to VFR from west to
east. West-northwest winds increase thruout the night, becoming 10-15 knots. A
few gusts in the 20-25 knots range possible.
Thursday and Friday...VFR. Northwest wind 10-15 knots with gusts 25 knots to
perhaps near 30 knots Thursday. Winds subside late in the day. Light northwest
winds Thursday night and Friday.
the Small Craft Advisory on the lower Delaware Bay has been
cancelled. Winds have fallen below 25 knots and are expected to
remain down through today.
A Small Craft Advisory remains in effect for the ocean waters
through 6pm Tuesday.
Winds will continue to gust in the northeast to east flow this
morning across the area waters with a trend more to the east through
the day. Winds may lull for a period of time today, especially
across the northern waters.
Seas have risen to 5 feet and are expected to remain elevated.
Tuesday...Small Craft Advisory extended into Tuesday for the Atlantic coastal waters
with Ely winds 15-20 knots and gusts to 25 knots. The 00z NAM was
indicating near gale force gusts but that is an outlier and appears
to be an effect of deepening the offshore low too aggressively. Seas
will increase from 4-5 feet in the morning to 6-7 feet during the afternoon.
Tuesday night and Wednesday...winds eventually turn to southerly Tuesday
night and Wednesday morning before turning westerly Wednesday
afternoon behind a cold front. The winds will weaken but seas in the
Atlantic may remain elevated near the 5 feet threshold for a Small
Wednesday night and Thursday...westerly winds increase to 15-20 knots
Wednesday evening and become northwesterly late. Gusts up to 30 knots are
possible in the southern Delaware Bay and coastal Atlantic waters.
Thursday night and Friday...northwest winds subside a bit to below Small Craft Advisory
the WSR-88D located at Fort Dix New Jersey will be down at least until
sometime today when the parts needed to repair the radar are
expected to shipped on site.
Marine...Small Craft Advisory until 6 PM EST Tuesday for anz450>455.