Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
528 am EDT Monday Mar 17 2014
low pressure centered off Cape Hatteras, North Carolina early
this morning will move east northeastward and out to sea today.
Cold high pressure will continue to build into our region from the
north for tonight and Tuesday. A frontal boundary is forecast to
approach from the west on Wednesday and it should pass through our
region on Wednesday night. High pressure is expected to follow for
Thursday and Friday. A cold front from the west is anticipated to
arrive on Saturday with another area of high pressure forecast for
Near term /until 6 PM this evening/...
no changes have been made to the winter weather headlines this
morning as snow continues to fall across the southern half of the
area and continues to slowly drift to east-northeast. An area of
low pressure will continue to slide off the North Carolina coast
this morning and move to the east-northeast and out to sea today.
Meanwhile, a short wave located across the Ohio River valley will
continue to move eastward today as well. Moisture continues to
move across the area with the southwest flow aloft. With the cold
high pressure building southward out of Canada and down the
eastern Seaboard, snowfall will continue through the morning
hours. The question is how far north the snowfall will get. The
high is fairly strong, and dry enough that it is expected to
suppress the snow from getting much farther north than where it is
now. We've had several inches of snow so far through the overnight
across southern New Jersey and the Delaware-Maryland-Virginia and will continue to
get several more inches here for a few more hours as the strongest
lift in the snow growth zone and frontogenesis are being maxed
now. These should begin to weaken as we approach sunrise, so
snowfall rates are expected to diminish as we approach the rush
hour. However, there could still be a few inches of accumulation
where our advisories and warnings are now. The highest snowfall
amounts are across central/southern Delaware-Maryland-Virginia and southern New
Jersey where it has been snowing the longest and heaviest.
Most of the guidance keeps the chance of light snow into at least
the middle-late morning hours, and possibly into the afternoon.
However, the RUC and hrrr actually have the snow dissipating
around or shortly after sunrise. Still, we will keep a chance of
snow in the forecast into the afternoon, with lowering chances as
we progress through the day.
For daytime highs, we took a blend of the mav/met MOS. However,
we used a majority of the warmer mav MOS for the northern third of
the area where they have the better possibility of seeing some
peeks of sun today, and the cooler met MOS for the rest of the are
where cloud cover may linger longer into the day.
Short term /6 PM this evening through 6 am Tuesday/...
any remaining snow across the area will have ended by the time
the evening rolls around. We may just have to deal with some
scattered cloud cover overnight, especially across the southern
areas, where some moisture may get trapped in the low levels. As
high pressure continues to nose its way down the eastern Seaboard
out of Canada, it will keep filtering cold air across the area.
Temperatures overnight will continue to be 5 to 10 degrees below
Long term /Tuesday through Sunday/...
cold high pressure is forecast to be centered over Quebec on
Tuesday morning and it will nose down the Lee of the Appalachians.
The center of the high is forecast to drift eastward on Tuesday
and Wednesday and it will lose its influence over our region
gradually. Temperatures will remain below normal for Tuesday and
they should approach normal on Wednesday.
A middle level trough that was moving onto the Pacific northwest
coast early this morning should make its way across the country.
The axis of the trough is forecast to pass over our region on
Thursday. A surface cold front in advance of the feature is
expected to pass through our forecast area on Wednesday night. We
are anticipating showers with and ahead of the frontal boundary
mainly on Wednesday afternoon and Wednesday evening.
Surface high pressure is expected to pass across the southeastern
states on Thursday and Friday. The northern edge of the air mass
should influence our region. Temperatures are forecast to be
slightly above normal.
Another middle level trough from the west should push a cold front
through our region on Saturday. Before the front arrives,
temperatures may rise near 60 degrees across the central and
southern parts of our forecast area, at least those areas not near
the ocean or the bays. The Saturday front is anticipated to bring
another round of rain showers to our region.
Chilly high pressure will follow saturday's cold front.
Temperatures should fall back below normal for Sunday.
Aviation /10z Monday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
Kabe...the snow should remain mostly to the south of kabe with
VFR conditions expected through the taf period.
Krdg and kttn...a period of MVFR conditions in snow is possible
before 1200z, then VFR conditions are expected through the balance
of the taf period.
Kphl, kpne and kilg...IFR conditions are anticipated through
about 1200z or 1300z. The snow should become light and spotty
after 1200z or 1300z with conditions improving to MVFR. VFR
conditions are anticipated from about 1800z or 1900z Onward.
Kmiv and kacy...IFR conditions in snow through about 1400z,
lifting to MVFR for the period from around 1400z until 2000z, then
A northeast to east wind at 10 knots or less at krdg and kabe.
For our remaining six taf sites including kphl, a northeast wind
around 10 to 12 knots gusting near 20 knots today diminishing to 6
to 10 knots for tonight.
Tuesday and Tuesday night....mainly VFR.
Wednesday and Wednesday night...mainly VFR with a chance of rain
showers lowering conditions to MVFR at times, especially in the
afternoon and evening.
Thursday through Friday...mainly VFR.
an area of low pressure will continue to slide off the North
Carolina coast this morning and move to the east-northeast and out
to sea today, while high pressure builds south across the eastern
Seaboard through tonight.
The Gale Warning for the northern Atlantic coastal waters off of
Sandy Hook was dropped and converted to a Small Craft Advisory as
winds no longer are expected to gust to 35 knots here.
The Gale Warning across the rest of the Atlantic coastal waters
and lower Delaware Bay was extended through this afternoon. Once
the gale force winds diminish, a Small Craft Advisory will likely
The Small Craft Advisory on the upper Delaware Bay was extended
through this afternoon.
Tuesday...a Small Craft Advisory is in effect on our ocean waters
for wave heights near or in excess of 5 feet.
Tuesday night through Thursday...Small Craft Advisory conditions
are possible, especially on our ocean waters.
Thursday night and Friday...no marine headlines are anticipated.
tidal departures along the New Jersey and Delaware oceanfront
were running about a half foot to a foot above normal early this
morning. The latest guidance and trends continue to suggest the
departures will not increase to more than about a foot to a foot
and a half above normal in the northeast flow. The resulting water
levels would not reach the minor flooding thresholds. Departures
of greater than a foot and a half would be needed around the times
of high tide today to cause a problem.
more snowfall records to fall and/or climbing higher in the
snowfall record department. Acy has the best chances:
Daily snowfall records for:
Allentown 4.2 in 1967
Atlantic City 1.6 in 1965
Philadelphia 3.5 in 1892
Wilmington 2.4 in 1965
In Philadelphia, we have had 13 separate calendar days in which
an inch or more of snow has fallen this season. We have a small
chance to make it 15 calendar days which would give this season
sole possession of second place. A more likely 14 calendar days
would tie US with 1898-99 while the record is 17 calendar days in
the 1917-18 season.
Speaking of second place, an additional 2.7 inches would give
Philadelphia (62.9 inches currently) the second snowiest season on
record, surpassing the 65.5 inches during the 1995-6 season. The
all-time record is 78.7 inches in 2009-10. It appears safe through
this event. If 6.6 inches or more of snow were to fall early next
week, it would be the first time ever there have been four double
digit months of snowfall in one season in Philadelphia.
Atlantic City (33.7 inches currently) needs one tenth of an inch
of additional snow to crack the top 10 snowiest seasons on record
and 8.7 additional inches to supplant 2002-3 as the 5th snowiest.
The most recent snowiest winter was 2010-11 (ranked 8th) at 38.0
inches. Numero Uno is the winter of 2009-10 at 58.1 inches.
Wilmington (52.9 inches currently) needs 3.1 additional inches to
supplant 1995-6 as the second snowiest season on record. The
record is 72.8 inches during the 2009-10 season.
Allentown seasonal snowfall ranks. We might not move up.
75.4 inches in 1993-4
71.4 inches in 1995-6
67.2 inches in 1966-7
66.9 inches in 2013-4
PA...Winter Weather Advisory until noon EDT today for paz070-071-
New Jersey...Winter Storm Warning until noon EDT today for njz016>018-
Winter Weather Advisory until noon EDT today for njz012>015-
Delaware...Winter Storm Warning until noon EDT today for dez001>004.
Maryland...Winter Storm Warning until noon EDT today for mdz008-012-015-
Marine...Gale Warning until 5 PM EDT this afternoon for anz431-451>455.
Small Craft Advisory until 6 PM EDT Tuesday for anz450.
Small Craft Advisory until 5 PM EDT this afternoon for anz430.