Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
359 PM EST Wednesday Feb 10 2016
low pressure over the Saint Lawrence valley will move into the Bay
of Fundy Thursday, while high pressure over the upper Mississippi
Valley moves into the middle Atlantic on Friday. A strong Arctic
cold front will move through our region on Saturday, sweeping low
pressure over the Outer Banks of North Carolina well out to sea.
High pressure will move into our area from the Ohio Valley on
Sunday, and move off the middle Atlantic coast on Monday. Two storm
systems are expected to join forces over the middle Atlantic,
and move up the East Coast on Tuesday and Wednesday.
Near term /until 6 am Thursday morning/...
tonight...negative tilt short wave probably produces flurries and
scattered dusting snow showers in the 02z-10z time frame, and
thought mostly I-78 corridor northward (possibly a connection to
Lake Erie snow shower plume) but there may be a batch that crosses
the Delmarva, enhanced by the Chesapeake Bay. Any snow amts under
1 inch. Will Post an overnight sts graphic which says less than 1
inch but in reality, expecting less than 1/2 inch within scattered
bands, mostly PA. Temperatures near normal. Gusty west winds to 25
miles per hour probably diminish for a while tonight. It may tempo clear after
sunset this evening and than probably partially clear toward dawn
after the short wave passage.
Short term /6 am Thursday morning through 6 PM Thursday/...
partly sunny and brisk. Scattered brief snow showers or flurries,
mainly I-78 nwwd where very unstable 925-700mb lapse rates and
semblance of a trough. Btv snow squall parameter prediction tool
has supportive indication. Gusty west northwest winds to 35 miles per hour
11 am to 3 PM. Maximum temperatures about 10f below normal.
Long term /Thursday night through Wednesday/...
the main concern is a period of wind-driven much below normal
temperatures, the coldest of the season so far, Saturday into
Sunday with increasing confidence of dangerously low wind chills.
Otherwise, the Friday through Wednesday time frame is generally
expected to be unsettled, with a cyclonic flow aloft.
Friday and Friday night, clouds will increase in advance of two
seperate short waves, one over the Great Lakes and another over the
middle Atlantic. These are expected to remain largely separate, with
only a chance of snow showers in the forecast for the Friday night
portion of the forecast.
Saturday and Sunday, with the passage of an Artic cold front
Saturday morning, much below temperatures are forecast. During this
time frame, 850 mb temperatures will plunge to around -25c at kphl!
We also expect northwest winds of 15 to 25 miles per hour with the potential
for gusts to 40 miles per hour Saturday into Saturday evening, tapering down 10
to 20 miles per hour with continued gustiness through Sunday morning. Low
temperatures of zero to 10 below zero are forecast for the entire
region, which leads to wind chill values dangerously cold in the
10 below to 25 below zero range Sunday night.
Monday through Wednesday, temperatures moderate quickly, returning
to near normal on Tuesday. The main uncertainty is the track of low
pressure organizing near the East Coast, with the 12z European model (ecmwf) near
the Appalachians and the GFS more offshore. In any event, this
will be an unsettled period of weather with the potential for both
snow and rain.
Aviation /21z Wednesday through Monday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
Remainder of today...VFR generally broken ceilings at or above 4000 feet. West
wind gust 20-25 knots.
Tonight...VFR with ceilings redeveloping mainly at or above 4000 feet. Those
ceilings may briefly lower to MVFR conds in bands of snow showers
sometime between 03z and 09z, especially vicinity kabe/kttn/krdg.
West wind gusts to 20 knots. Confidence: average.
Thursday...VFR scattered-broken at or above 4000 feet. West-northwest wind gusts
around 30 knots in the afternoon, possibly isolated 35 knots. Some brief
MVFR restrictions in isolated snow showers and flurries possible
vicinity krdg/kabe. Confidence: average.
Thursday night...VFR conditions.
Friday and Friday night...predominantly VFR. MVFR possible in
scattered snow showers.
Saturday and Sunday...VFR conditions expected. Northwest winds
15 to 25 knots with gusts to 30 knots possible, mainly Saturday
and Saturday night.
Monday...VFR conditions. MVFR possible in rain or snow showers.
sst's are around 5 to 8f warmer than normal for February and these
water temperatures warmed about 5 degrees from the middle January water
temperature tumble. The reasoning for the warming, even in Delaware Bay
is not well understood by myself but it has occurred and I think
becomes a more important player in aiding momentum Transfer through
these cold air advection episodes by steepening the boundary layer
Glw continued. Funneling and earlier start to the deepening boundary
layer mixing for Delaware Bay should permit a few gusts to 35 knots vicinity
sjs, bwine...lws sometime between 1 am and 4 am Thursday.
Confidence on the starting time of gale gusts there is average.
Thereafter...west-northwest gale gusts spread to the Atlantic waters of New Jersey
and Delaware during the morning, becoming most persistent Thursday
afternoon/evening when a few gusts to 40 knots are expected. High confidence.
We have no wind data at 44009 so to verify, we have 44065 and we
use multiple coastal wind observations adjacent the water including
nos/USGS/weatherflow mesonet platforms.
Thursday night...Gale Warning in effect through 6z...followed by
Small Craft Advisory /sca/ winds through early Friday morning.
Winds will increase again to Small Craft Advisory levels Friday night ahead of an
Arctic cold front. Winds increase to gale force late Friday night
and may maintain gales through Saturday night. A Small Craft Advisory may be needed
on Sunday, with sub-Small Craft Advisory on Monday.
near record cold is expected for portions of our area Sunday
morning and by far the coldest air of the season so far.
Anticipating temperatures throughout our forecast area within several
degrees of zero (wind is the equalizer) anytime from midnight
through 8 am Sunday except colder kmpo (near -12f). This has been
advertised by the GFS/European model (ecmwf) 2m temperatures cyclically since at least the
00z/7 operational cycles. Therefore, best chance for record equaling
or exceeding for Valentines day the 14th would be kabe, kttn, kphl
Snowcover may help a bit I-95 northwestward...and we'll see where
we are with snowcover by Thursday evening. New dustings appear on
the way the next 30 hours.
2015-16 so far rer 14th
Abe 8......... -1 1979
Acy 10........ -6 1979
Phl 12........ +2 1979
Ilg 12........ -4 1979
Ridge 10........ -4-1983
Ttn 9......... 0 1916
Ged 13........ -7 1979
Mpo -1........ -12 1970
So, this will be wind driven cold with many areas experiencing
wind chill values of 15 to 25 below zero...possibly 30 below in
the hills and mountains of northwest New Jersey and northeast
Marine...Small Craft Advisory until 6 am EST Thursday for anz450>455.
Gale Warning from 6 am Thursday to 1 am EST Friday for
Gale Warning from 1 am to 11 PM EST Thursday for anz430-431.