Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
924 PM EST Thursday Mar 5 2015
Arctic high pressure builds in overnight and Friday. The high
will then settle to our south on Saturday. A weak low pressure
system will track to our north late Sunday into Monday, pulling a
cold front across our region on Monday. High pressure should then
build into the area Tuesday into Wednesday, with the next cold
front scheduled to arrive later Wednesday into Thursday.
Near term /until 6 am Friday morning/...
storm over: pns and rer's are posted. The pns for snow will
further update overnight.
Have raised temperatures overnight because of increased wind.
Record lows still appear to have a good chance of occurring at
kabe and krdg, provided late decoupling occurs near sunrise.
The 18z NAM was much better at at attempting to depict the
gustiness across the forecast area. The 00z NAM suggests wind
gusts will increase 5 knots toward 06z before decoupling attempts to
become more extensive around 09z.
At 02z, the backedge of the thick high cloud deck was moving east
of the Appalachians.
Low temperatures tonight are blended met/mav and additionally for
the east PA and nnj Countryside only, added the modeled GFS two
Wind chills are likely to fall to near zero across most of the
region, with the Poconos seeing wind chills which may get close to
advisory threshold for a few hours. Given the limited window and
marginal values in terms of and advisory, will just continue
mention in the severe weather potential statement.
Short term /6 am Friday morning through 6 PM Friday/...
sunny day with high pressure building in on Friday but still cold.
Did go a touch warmer than mav/met given the cool daytime bias
with snow cover. Other elements straight mav/met. Continued
northwesterly winds under 10 miles per hour or so.
Long term /Friday night through Thursday/...
the overall synoptic setup is comprised of an upper-level trough
from the Midwest to the northeast and middle Atlantic. As short wave
energy moves through the flow, this feature should amplify a little
for a time or two. This should eventually weaken as energy ejects
across the Southern Plains late in the weekend and early next week,
with a ridge potentially building off the southeastern U.S. Coast.
This results in the upper-level flow turning more zonal next week.
We used a model blend for Friday night through Sunday, then went
with the 12z wpc guidance thereafter. We then made some adjustments
after additional collaboration with our neighboring offices.
For Friday night and Saturday...a short wave trough looks to slide
across the area, however a dry airmass results in no precipitation.
At the surface, high pressure builds over the area however its
center slides to our south through Saturday. This will result in a
gradual return flow being established and after a very cold start
Saturday, some moderation is expected in the afternoon.
For Sunday and Monday...a short wave is forecast to track near the
Midwest and Great Lakes Sunday, then well to our north Monday. This
will drive weak low pressure well to our north, however a cold front
is forecast to move through during Monday. It appears that the
moisture will be lacking with this feature as much of the lift
occurs well to our north. There could be a snow shower though Sunday
night into Monday across the far northwest. Otherwise, the airmass
is forecast to continue to modify as the flow comes more from the
west and not the north.
For Tuesday and Wednesday...high pressure should shift to our east
as a cold front moves across the Midwest and the Great Lakes. Low
pressure appears to track well to our north once again, with a warm
front lifting mostly to our northwest. While the flow looks fairly
weak, enough warm air advection is expected to occur to allow for further
moderation of the airmass with many areas getting into the lower 50s
Wednesday afternoon. The cold front should be arriving late
Wednesday, however given the track of the surface low and short wave
aloft it also looks to be moisture starved.
For Thursday...a weak surface high is anticipated to move across the
area, while a frontal boundary is draped from near Maine to the
Great Lakes then into the Central Plains. The airmass should be much
milder with afternoon highs getting into the 50s. The ocean and
Delaware Bay are cold and if there is light enough flow, then a
cooling affect can be expected closer to the coast.
Aviation /02z Friday through Tuesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
Remainder of tonight...VFR ceilings become VFR clear from west to east
between 3z and 6z. North-northwest wind gust around 20 knots
diminishing toward sunrise.
Friday...VFR clear with scattered-broken cirrus at or above 20000 feet late in the day.
Friday night through Sunday...VFR overall. A weak system moving by
later Saturday should result in more clouds, however any
precipitation looks to stay to our north and west.
Monday and Tuesday...VFR overall. A weak cold front moving through
Monday should result in more clouds, however it appears that it
moves through dry.
extending the Small Craft Advisory along lower Delaware Bay through much of the
night. We may need to add a short fuse Small Craft Advisory for upper Delaware Bay around
05z? Small Craft Advisory continues along the altc coastal waters through the
For Friday, winds and seas should remain below Small Craft Advisory criteria.
Friday night and Saturday...the conditions are expected to be
below Small Craft Advisory criteria, however the winds will
increase some from the west-southwest during Saturday. There is a
chance for some light freezing spray Friday night and Saturday
Sunday through Tuesday...we are anticipating sub Small Craft
Advisory conditions as a weak front moves through mainly during
with a snow cover in place and another Arctic airmass settling
into the region and radiational cooling occurring we have another
chance for more record lows across the region.
Acy 10 1888
phl 10 1978
ilg 11 1926
Abe 7 1960
ttn 7 1872
Ged 10 1978
ridge 7 1978
mpo -5 1909
The the 9 PM forecast has krdg and kabe breaking their record low
Acy 10 1890
phl 9 1960
ilg 11 1960
Abe 1 1960
ttn 7 1890
Ged 3 1960
ridge 10 1989
mpo -18 1911
It appears that reading and Atlantic City have the better chance
of getting to their record low Saturday morning.
Record daily snowfall for Thursday March 5
Rer's posted for kilg and kacy...both 7.0 inches.
Phl had 7.5 and Allentown 6.7.
Kacy 0.3 - 1960
kilg 3.7 - 1981
kabe 7.0 - 1917
kphl 8.8 - 1981
Fwiw...water equivalence of total snow depth in portions of eastern
PA is now well over 3 inches.
Marine...Small Craft Advisory until 6 am EST Friday for anz450>455.
Small Craft Advisory until midnight EST tonight for anz431.
near term...drag 923