Area Forecast Discussion
Issued by NWS Mt. Holly, NJ-- Remove Highlighting --
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FXUS61 KPHI 160806 CCA
Area Forecast Discussion...CORRECTED
National Weather Service Mount Holly NJ
306 AM EST Thu Feb 16 2017
An area of low pressure will continue to intensify as it moves
into the Canadian Maritimes tonight and lingers there through
Friday. Weak high pressure affects the area Friday into Friday
night. An area of low pressure will pass well to our north
Saturday night into Sunday, pulling a cold front across our area
early Sunday, then another boundary may move into the area
later in the day. High pressure affects the area Monday into
Tuesday, before moving offshore Tuesday night.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Strong cold air advection will continue through the day under a
continued northwest flow pattern. A mid level trough axis
digging southeast on the back side of the closed low will cross
our region later today. The combination of this plus the
continued strong northwesterly flow should result in scattered
snow showers across the Poconos, Lehigh Valley and northern NJ.
As with the snow showers last evening, expect most places to see
a dusting, though localized amounts up to an inch are possible.
As for the winds, expect the strongest winds to be through
early afternoon before the pressure gradient begins to decrease
late in the afternoon. The mixed layer could be as deep as
through 800mb. If this is the case, could see peak gusts up to
Trended the max temperature forecast down slightly as mid level
cloud deck has already moved over much of the region, and
should persist for much of the day, limiting solar insolation.
Highs should be about 10 to 15 degrees below highs yesterday.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
Closed low continues to lift further away from the region. As
it does so, the pressure gradient over the region will continue
to decrease. By late this evening, expect winds across the
region to drop off to around 10 mph.
With the winds dropping off and the mid level cloud deck
expected to erode, should see efficient radiational cooling,
with lows ranging from the teens to mid 20s. Even so, this will
mean lows will be near or just slightly below normal.
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
A mostly dry forecast for the majority of the extended.
For Friday, low pressure will continue to drift through the
Canadian Maritimes and the pressure gradient will weaken across
our area as weak high pressure moves across the area through
Friday night. The northwest winds are not expected to be as
strong as they were during the day Thursday, but they will still
elevated with gusts around 20 mph at times.
On Saturday, a warm front may lift north of the area as low
pressure moves across southern tier of Canada. The low passes to
our north overnight Saturday into early Sunday. This will bring
a couple of cold fronts/surface troughs across the area early
Sunday morning and later Sunday afternoon. The airmass is
forecast to be relatively dry and there is not much in the way
of short waves/vorticity impulses to help create any shower
activity. So we`ll keep the forecast dry.
High pressure is then expected to affect the area on Monday
into Tuesday. Dry weather should continue on Monday, but a warm
front may pass to our west on Tuesday as high pressure begins to
shift offshore. A couple of short wave/vorticity impulses may
cross the area Tuesday through Wednesday which may help create
some isolated showers.
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
VFR conditions are expected through the TAF period. Mid level
deck between 4000 and 6000 ft AGL is expected to persist through
at least 21Z before slowly dissipating.
Winds are expected to stay northwesterly through the TAF
period. Peak winds are expected between 15 and 21Z. At their
peak, winds could be as strong as 20G30KT. We should see a
gradual decrease in speeds between 21 and 03Z, before settling
in around 10KT through the rest of the night.
Friday-Monday...Generally VFR expected, although MVFR CIGS may
be possible during the day if clouds develop. Gusty winds 15-20
knots during the day.
The gale warning on the lower Delaware Bay has been converted
to a Small Craft Advisory. The SCA on all of the Bay now goes
through midnight tonight. No changes to the gale warning on the
Atlantic coastal waters.
We are in a temporary lull in the winds currently, but they are
expected to increase once again in the pre-dawn hours with gale
force conditions expected on the ocean waters and small craft
advisory conditions expected on the Delaware Bay. Winds are
expected to slowly subside through the late afternoon and
evening hours. Once winds drop below gale conditions on the
Atlantic coastal waters, an SCA will be needed.
Friday...Small Craft Advisory level conditions possible early,
then diminishing during the day.
Friday night-Monday...Sub Small Craft Advisory conditions
expected. Winds may gust around 20 knots at times however.
The month as a whole has so far averaged 3 to 5 degrees above
normal through Valentines Day, except just a little more than a
degree above normal at KMPO. There isn`t any sign of long
duration substantially colder than normal air coming in February
and in fact some of the guidance is suggesting near record
warmth is possible this weekend. We`ll take a closer look at
that later today. Suffice to say...February is highly likely to
average above normal. We`ll try and figure to what degree, also
later today. Snowfall continues to average well below normal.
It`s still too early to look at the lower value ranking for the
season, especially since there is some ensemble guidance
indicating a more active storm track developing in our area by
the first week of March.
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MARINE...Gale Warning until 6 PM EST this evening for ANZ450>455.
Small Craft Advisory until midnight EST tonight for ANZ430-431.
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