Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
744 am EST Thursday Dec 18 2014
low pressure to our northeast will continue to move towards the
northern Atlantic while high pressure begins to nose in from the
northwest. Weak low pressure in Georgia Saturday morning is forecast
to stay south of the region on Sunday. A better defined low will
form along the Carolina coast and move northeast off the New Jersey
coast. A much more potent system looks to deepen across the southern
Great Lakes on Wednesday as it impacts our region.
Near term /until 6 PM this evening/...
93o am first cut estf update...added more cloud cover through 20z i95
corridor nwwd and boosted winds 3-5 knots. 35 knots at kmpo at
12z...going to be a breezy day.
From this point forward lwx issues our public products today as
we are down for software updates. Mount Holly resumes its normal
County Warning Area responsibility around 4 or 5 PM.
From the previous forecast shift:
With continued northwest flow, and the Continental polar air mass
continuing to settle in over the region, expect a cooler day
today. Expect highs to be about 5 to 10 degrees lower as compared
to yesterday, near the normals for this day. Breezy northwesterly
winds will continue through at least the first half of the day,
before the pressure gradient decreases, resulting in decreasing
Short term /6 PM this evening through 6 am Friday/...
one last short wave trough on the back side of the departing upper
level low will approach the region over night, but with continued
dry air advection in the boundary layer, do not expect any
precipitation, only increasing middle and upper level clouds across the
northern half of the region. With the surface high sliding closer to
the region, expect boundary layer winds to decouple soon after
sunset. This could set up prime radiational cooling conditions over
the southern half of the region if previously mentioned middle and
upper level clouds stay confined to the north. For now however, have
generally stayed close to the guidance which is near normals.
Long term /Friday through Wednesday/...
middle-level flow the next couple of days is rather flat though a
change to that pattern appears likely by the end of the weekend. A
deep trough emerges across the central U.S. By Tuesday as multiple
Pacific northwest waves round the base of the trough and across our
region...we are heading for a very unsettled period by early next
Friday - Saturday...both days look dry. Friday should be dominated
by Great Lakes high pressure which should yield party cloudy skies.
The past couple of days Saturday looked to be the transition day
into the stormier pattern but with the once East Coast storm began
to trend weaker and weaker we look to be drier and drier. There is
some northern stream energy to contend with late Saturday night that
could touch off a few showers as it passes through but these should
be of little consequence.
Sunday...an inverted trough may throw back some moisture across the
area as a weak wave of low pressure moves well offshore of our
region. Where we once had likely probability of precipitation have now trended to chance or
slight chance and there is the possibility of no chance in the
coming days. As for ptypes, the interior zones have the best chances
of seeing snow on Sunday morning before a slight warming trend is
expected. Precipitation looks to be light in nature everywhere.
Monday - Tuesday...once the aforementioned system above departs
another, better defined system moves off the Carolina coast and out
to sea on Tuesday. Onshore flow ahead of the system will allow for a
warming low-level thermal profile so any precipitation will be
liquid with some mixing possible in the far northwestern zones.
Wednesday...still watching a large low pressure form to our west and
track into the Great Lakes region on Wednesday. This would keep our
region under a warming thermal profile with a lot of moisture to
work with...an all liquid event is expected at this point. What is
interesting with the latest model runs is how they are seemingly
weakening the primary low as it moves into the lakes allowing for
another, stronger, piece of Pacific northwest energy to produce cyclogenesis
across the mid-Atlantic. If this eastward trend and cyclogenesis
continues we could be singing a different tune over the next several
days. None-the-less, lots of moisture, winds, and possibly
convection, are looking better and better...we continue the likely
probability of precipitation this far in advance.
Aviation /13z Thursday through Monday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
Klwx issues tafs from this point forward through the day. Mount
Holly resumes taf issuance around 21z. Software upgrades for Mount
Holly today. Mount Holly will be on the aviation related phone
Today...VFR scattered-broken 3500-4500 feet. Northwest wind gusts 22-30 knots subside
Tonight...VFR with SC slowly diminishing though SC may hold on much
of the night near and just north of kabe/krdg due to a developing inversion
near 5000 feet. There will be a period of middle and high clouds racing
eastward basically near and south of klns-kmjx near 06z/19. Gusty northwest
winds subside somewhat...few gusts 15-20 knots.
Friday - Saturday...VFR. Northwest winds veer towards the
north-northeast by Saturday.
Sunday - Monday...sub-VFR possible with scattered rain/snow showers.
a Small Craft Advisory, primarily for winds, continues over the Bay
through noon, and over the Atlantic coastal waters through late this
afternoon. Northwesterly winds of 15 to 25 kt, with occasional gusts
above 30 knots can be expected through this time. Winds should diminish
slightly this afternoon. However, gusts near or above 20kt will be
possible through the overnight hours.
Friday...mostly sub-advisory conditions are expected. Some northwest
wind gusts could still be in the 20 plus knot range, though.
Confidence: above average.
Saturday - Sunday...sub-sca expected for the most part. Seas remain
around 3 to 4 feet. Confidence: average to slightly below average.
Monday...Small Craft Advisory conditions should present themselves later on Monday
under a strengthening easterly flow and building seas. Confidence:
Marine...Small Craft Advisory until 5 PM EST this afternoon for
Small Craft Advisory until noon EST today for anz430-431.
near term...drag/Johnson 743