Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
359 am EST sun Nov 29 2015
a cold front will move south of the region today and tonight while
high pressure builds in from eastern Canada and New England. The
high will move offshore into the Gulf of Maine Monday. The frontal
boundary to our south will start to return back to the north as a
warm front Tuesday before it lifts through our area Tuesday night.
Meanwhile, low pressure is expected to track eastward across the
Great Lakes Tuesday. A cold front will move through the Middle-Atlantic
States Wednesday as the low lifts into eastern Canada. High pressure
builds in from the west late in the week and into the weekend.
Near term /until 6 PM this evening/...
a frontal boundary located just south of the region will continue to
slowly move even further south today. The result will be cooler and
drier advecting into the region from north to south. From
Philadelphia to central New Jersey and points north, clouds will be likely
start to break up some in the morning and early afternoon hours.
Locations even further south such as the Delaware-Maryland-Virginia will likely hang
on to cloudy skies for the day. Some light rain showers will depart
the region as well today. The latest hrrr and rap runs show the
potential for these to linger across southeast PA and central New Jersey through
the morning and into the early afternoon across the Delaware-Maryland-Virginia.
Temperatures will range from near 30 in the Poconos and northwest New Jersey to the
middle 40's near Philadelphia to around 50 in the southern Delaware-Maryland-Virginia
this morning. Cloud cover will likely mean little change in
temperatures today across the Delaware-Maryland-Virginia with the cold air advection. Further north,
some warming into the upper 40's is likely with more sunshine. The
exact timing of clearing will have an impact on high temperatures.
Raw model temperatures, particularly the European model (ecmwf) linger clouds and rain
which would imply the forecast is to warm. On the other hand, the
faster GFS may make the forecast a couple of degrees to cool. The
met and mav guidance sets may not be capturing the northerly winds
and cloud cover enough today, so the forecast is a degree or two
cooler than met/mav.
Short term /6 PM this evening through 6 am Monday/...
the frontal boundary will still be close enough for a mostly
cloudy night across the Delaware-Maryland-Virginia. For the remainder of the region,
skies will be clear as high pressure moves across New England.
Northerly winds from 5 to 10 miles per hour may be just strong enough to
prevent ideal radiational cooling along with any fog. However, this
forecast does show some typical spots radiating a few degrees
cooler than the met/mav guidance sets with lows. Lows will range
from the 20's north to the 30's south.
Long term /Monday through Saturday/...
high pressure over New England Monday morning will move into the
Gulf of Maine in the afternoon and evening. The high will still
continue to ridge down the eastern side of the Appalachians. An
easterly flow off the ocean will likely lead to the development of
marine stratocu in the morning near the coast that expands inland
throughout the day. Additional cloud cover is expected to develop
during the day across our southern zones (and expand northward
during the night across our northern zones) as winds back more out
of the south once the low-level ridge axis progresses downstream of
US and produce an overrunning setup. We may even see isolated
sprinkles or very light rain showers develop later in the day and
evening from approximately the Delaware Bay southward. High temperatures on
Monday will be slightly below normal with the cad wedge overhead,
onshore flow and increasing cloud cover.
A closed low is forecast to track eastward from the upper Midwest
late Monday night to the Great Lakes on Tuesday and Tuesday night.
Southerly flow aloft ahead of this system will strengthen over the eastern
Continental U.S. During this time. This will produce an overrunning setup over
our region with the west-east oriented front that just moved through our area
positioned just to our south. Expect rain to expand back into our
area late Monday night into Tuesday.
There is a small window for the airmass to radiate to near freezing
Monday evening in our northern-most zones (carbon-Monroe-Sussex
counties) if the cloud cover moving in from the south holds off
until later. If this happens, then precipitation could begin as a brief
period of freezing rain or drizzle early Tuesday morning in the
sheltered valleys along and north of I-80 (where The Pocket of cold
air near the surface is typically hardest to scour out). Based on
the latest wpc ice and sref temperature/ptype probabilities, the chance for
ice accrection is only about 20 percent...not high enough odds to
mention in the severe weather potential statement but at least communicate it to the public in the
The rain will probably be steadiest and possibly moderate for a
period sometime late Tuesday when the warm front lifts northward
through our area and then again on Wednesday when the cold front
arrives from the west. There is still some timing differences with
the fropa, so it is unclear if precipitation ends early (gfs solution) or
late in the day (ecmwf/Gem solution) on Wednesday.
Expansive high pressure builds eastward into the area Thursday and
Friday. Guidance continues to trend with a more amplified ridge
building over the eastern Seaboard next weekend while the surface
high sits over US. Expect dry conditions and temperatures to be at or
slightly below normal late in the week and into the weekend.
Aviation /09z Sunday through Thursday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
MVFR ceilings and visibilities are present with the band of showers in
association with the cold front at ilg-miv-Acy while terminals to
the north have improved to VFR overnight.
Winds will be northerly to northeast and continue today with
wind speeds generally 5-10 knots. Ceilings and visibilities will slowly
improve from north to south with our southern taf sites in VFR
range by this afternoon.
Monday...MVFR ceilings should develop initially near the coast (acy/miv)
in the morning and then possibly expand inland toward the I-95
terminals through the afternoon. Light Ely winds at or below 10 knots.
Monday night...MVFR ceilings at most terminals during the evening. Light
rain will gradually expand northwest-wd late. Some terminals such as ridge-
ilg could deteriorate to IFR toward daybreak if steady rain develops.
Tuesday and Tuesday night...MVFR with periods of IFR in rain likely.
Light Ely winds become southerly as a warm front lifts northward through the
Wednesday...MVFR/IFR conditions with showers at the onset improve
from west to east behind a cold front. Timing of the front still
a bit uncertain.
Wednesday night through Thursday...VFR. Westerly winds behind the cold front
may occasionally gust to 25 knots through Thursday morning.
seas are currently around four feet on the ocean waters and will
likely remaining around four feet through this evening. Overnight seas
should increase to around five feet with increasing northeasterly
winds as well. Some of the gusts may get close to 25 knots but the
majority of data suggests top gusts through tonight will be below
25 knots. With the prospects for five foot seas on the increase will
issue a Small Craft Advisory starting at 10 PM this evening.
Monday...Small Craft Advisory issued for the Atlantic coastal zones with seas of 5-7
feet expected. Ely winds will be 15-20 knots but gusts to 25 knots with
perhaps a few gusts to 25 knots at our offshore buoys.
Monday night and Tuesday...onshore flow around 15-20 knots continue but
with seas 4-6 ft, the Small Craft Advisory will likely need to be extended into this
Tuesday night and Wednesday...winds eventually turn to southerly Tuesday
night and Wednesday morning before turning westerly Wednesday
afternoon behind a cold front. We may see a brief lull in Small Craft Advisory
conditions during this time.
Wednesday night and Thursday...Post-frontal surge will produce a westerly
wind near 20 knots but strong mixing may yield gusts that approach
gales through early Thursday.
the WSR-88D located at Fort Dix New Jersey will be down at least until
Monday, November 30. The parts needed to repair the radar are on
Marine...Small Craft Advisory from 10 PM this evening to 6 PM EST
Monday for anz450>455.