Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
336 PM EDT Monday Mar 30 2015
a fast moving low pressure system should sweep through the area
tomorrow. A high pressure system will build into the region for
Wednesday and move offshore on Thursday. The next cold front should
move through the region late Friday. A secondary cold front should
move through the area late Saturday followed by a high pressure
system for the start of next week.
Near term /until 6 am Tuesday morning/...
the surface cold front has crossed the area and an upper vorticity maximum is in
the process of crossing the region. Varying amts of low clouds
expected for the next few hours...with more clouds north. The cloud
cover will diminish tonight as well as the gusty west winds. Mostly
clear skies overnight with some increase in high clouds late. Low
temperatures tonight will drop into the upper 20s or low 30s
north/west and bottom out in the upper 30s/low 40s south.
Short term /6 am Tuesday morning through 6 PM Tuesday/...
a fast moving clipper system will be good for about 6 hours of
precipitation across the area Tuesday. The good news is that most
areas will have rain. Only the higher elevations of the southern Poconos
will have snow Tuesday with a small accumulation...1 to 2 inches
possible. The precipitation will arrive across the west during the
late morning and will overspread the del valley/Delaware-Maryland-Virginia and New Jersey by
afternoon. Overall quantitative precipitation forecast of about 0.25 expected. High temperatures Tuesday
will range from the low/middle 40s north to the middle 50s south. Highs
will remain closer to the middle 30s over the higher elevations north.
Long term /Tuesday night through Sunday/...
long term begins with a split flow pattern and the departing
clipper system, but by the end of the week we see the upper level
pattern transition to more of a zonal flow pattern.
Tuesday night...clipper system exits. Models are in relatively
good agreement of how quickly it will exit (with precipitation cutting
off for all but coastal areas by 06z), even though there remain
some minor differences with the track of the low.
Wednesday and Thursday...surface high builds over our region
Wednesday, but quickly shifts off shore. As it does so, low level
flow will become more southerly and southwesterly resulting in
significant warm air advection. Highs on Thursday should be about
10 to 15 degrees higher than Wednesday, and above normal!
Thursday night into Saturday...models came into considerably
better agreement over the last 24 hours, with the GFS generally
trending more towards the European model (ecmwf) solution. Models are in relativelygood
consensus that we will stay in the warm sector Thursday night into
early Friday until the initial cold front slowly slides through
Friday afternoon into Friday night. Through this time though, a
weak upper level short wave trough, and being under the right rear
quadrant of an upper level jet will allow for some chances of
rain even before the front enters the region. Chance for rain
continue with the passage of the front and as the next upper level
jet approaches the region.
Sunday into Monday...still considerable uncertainty how quickly
the next cold front will move into the region, and when it does
if there will be any precipitation. For now, continued to keep the
frontal passage dry as there will be limited opportunity for
moisture advection between the two frontal passages.
Aviation /19z Monday through Saturday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy, and surrounding areas.
The cold front has crossed through the are with the
drier air arriving along with a decent gusty west to northwest wind.
The winds gusts will continue into the early evening...before
diminishing. Sky cover will be mostly scattered into the evening with
mostly sky clear overnight. A few areas of bkn060 will move across the northern
areas through 6 PM local.
A clipper system will approach quickly Tuesday. Clouds will increase
through the morning and then lower conditions will arrive across the
del valley during the afternoon. Mostly rain expected with snow
possible over the higher elevations of the far north (srn poconos).
MVFR conditions were placed in the 30 hour taf...some guidance
suggests that conditions could be lower...more details on this with
the 00z tafs. Winds will be mostly light Tuesday with SW winds during
the first part of the day.
Tuesday night...conditions improving as precipitation moves out through
the overnight hours.
Wednesday through Thursday...generally VFR conditions. Breezy
southwesterly winds later on Thursday.
Thursday night through Friday night...MVFR conditions expected
with rain showers. Slight chance of thunderstorms Thursday night
into Friday morning as the front moves through.
Saturday...conditions improving as precipitation moves out.
west to northwest winds will continue to freshen behind the
departing front. While with mixing across the cold waters will not
be ideal...we will continue with the present Small Craft Advisory flag for gusts over
del Bay. Looks like most of the gusts will be 20 to 25 kts. Over the
ocean and 5 to 6 feet seas will continue and gusts of 20 to 25 knots
should round out the day/evening. The Small Craft Advisory flag across the ocean
expires at 06z. Sub-Small Craft Advisory late after that and into Tuesday morning. The
next clipper Tuesday could once again produce Small Craft Advisory winds Tuesday afternoon
into the evening. The next shifts can consider this once the present
flags come down.
Tuesday night...winds and seas should remain just below Small Craft Advisory
Wednesday...sub Small Craft Advisory conditions expected.
Thursday through Friday...southerly and southwesterly winds will
likely increase above 25 knots for at least part of this period. Seas
on the ocean will likely increase to Small Craft Advisory criteria as well. Agree
with previous shift that wave watch guidance is a bit too high for
wave heights with this pattern, so undercut guidance slightly.
Saturday...considerable uncertainty, but waves above 5 feet are
Marine...Small Craft Advisory until 2 am EDT Tuesday for anz450>455.
Small Craft Advisory until 6 PM EDT this evening for anz430-