Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 162030
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
330 PM EST Thu Feb 16 2017

.SYNOPSIS...
An area of low pressure will continue to intensify as it moves into
the Canadian Maritimes tonight. Weak high pressure will affect the
area on Friday and persist into Friday night. An area of low
pressure will pass well to our north Saturday night into Sunday,
potentially pushing a weak cold front through the northern Mid-
Atlantic during the second half of the weekend. High pressure will
affect the area Monday into Tuesday, before moving offshore Tuesday
night. Another cold front is possible next Wednesday or Thursday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Remainder of this afternoon...isolated flurries diminishing and
skies clearing. Gusty west northwest to 30 mph continuing...isolated
35 mph.

Tonight..it rapidly clears. Any lake effect cold trough aloft flurries
and isolated snow showers near and north of I-80 high terrain dries
out late at night. Lows near normal with diminishing gustiness.

Forecast basis: 50 50 blended 12z/16 GFS/NAM MOS.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Mostly sunny. Some cirrus at times. Northwest winds half as strong
when compared to today and backing to westerly and southwesterly
during the afternoon. Max temps near normal.

Forecast basis: 50 50 blended 12z/16 GFS/NAM MOS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Overview...the period starts with surface high pressure in control
and increasing mid-level heights. The building mid-level ridge looks
like it will peak Saturday morning and weaken a bit Saturday
afternoon and night. A weak or decaying cold front will try to push
through the region early on Sunday, but how far south is in
question. Stronger mid-level ridging ramps up again across the
eastern U.S. on Monday as the SoCal storm pushes into the 4 corners
region and then Rio Grande River Valley region. 500 mb heights peak
over the forecast area Monday night into Tuesday. Weaker mid-level
ridging remains in place on Wednesday and Thursday and should
diminish the effects of the next upstream cold front.

Temperatures...For comparison, normals for KPHL 44/28. Averages will
run above normal through the forecast period...mainly 10 to 15
degrees above daily averages.

Precipitation...Looking dry through the first half of the forecast
period. The second half, Tuesday through Thursday, will be painted
with small pops. Temperatures support all rain with the exception of
the northern zones where they could see some diurnal frozen
precipitation.

Winds...Mainly 15 mph or less through the period. Some higher gusts
possible at times across the higher terrain and along the coast.

Impacts...Probabilities are low through the period, although the
northern zones could see some snow next week. Widespread impacts are
not expected at this time.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

VFR conditions will continue at the terminals through the TAF period.
Ceilings around 5000 ft starting to clear late this afternoon with
mainly clear skies overnight. Some high cirrus will likely be
around the region overnight and through much of Friday.

Main concern rest of today continues to be the winds. A strong
northwest wind will continue through this afternoon with the
higher gusts (27 to 32 kts) dropping off between 22-00Z.
Sustained winds around 15 knots will continue through 03-06Z
tonight and then winds will drop down to around 10 knots
overnight and into early Friday. Winds on Friday will start to
turn more to the west southwest, mainly towards the afternoon
with max gusts under 20 kt.

OUTLOOK...

Friday Night through Tuesday...Mainly VFR expected with light winds
overnight and 10 to 15 kt during the daylight hours.

&&

.MARINE...
Marginal gale in progress Atlantic waters. Extended a few hours
into the evening due to a small uptick in momentum transfer
occuring now and forecast into the evening then a slow subsiding
of winds from there. Once winds drop below gale conditions on
the Atlantic coastal waters, an SCA will be needed.

SCA on DE BAY was extended through most of the night for the
slight uptick in the last gasp cold trough aloft instability
momentum wind transfer occuring now. It could gale on lower
Delaware Nay at times this evening. its possible we may need to
issue a 5 hour Gale Warning depending on 4 PM LWS and SJS CMAY
winds which have increased since 230 PM.

Quieter winds and seas Friday.

OUTLOOK...

Friday Night...Sub Small Craft Advisory conditions expected.
Diminishing offshore winds.

Saturday through Monday...Sub Small Craft Advisory conditions
expected. Offshore winds may gust 15 to 20 knots at times.

Tuesday...Sub Small Craft Advisory conditions expected with winds
becoming onshore.

&&

.CLIMATE...
Updated 245 PM Thu Feb 16 and please do not expect any further
updates prior to late Friday or Saturday.

Projecting widespread top 10 warmest February on record in our
forecast area. Confidence: above average. Details below.

Seasonal average (DJF) temperature projecting widespread top 14.
PHL is projecting #9 warmest, ABE #6 and ACY #12. Confidence:
above average.


February:

The month as a whole has so far averaged 3.4 to 5.5 degrees above
normal through the 15th, except 1.4 above normal at KMPO. There
still isn`t any sign of long duration substantially colder than
normal air coming this month and in fact some of the guidance
is suggesting near record warmth is possible either this
weekend and maybe the middle of next week (date and climate
location dependent).

Just the 7 day period of tomorrow through the 23rd should average
close to 10 degrees above normal.

The following projection is for Philadelphia with remainder of
the area relationship discussed.

Using this mornings low of 33 and the NWS forecast through the
22nd (see SFTCTP), and then FTPRHA max/min for PHL D8-11, and
the normal the last two days of February (max min of 47/30) we
project a monthly average of 41.9 degrees at PHL (2 degrees
higher than the current first 15 day average). Normal for
February is 35.7 or a projection of 6.2 degrees above normal.
This would make February the 2nd warmest in our period of record
dating back to 1874. The warmest February on record was 42.2F
in 1925. Ninth warmest is 40.1 degrees, so you see that we have
1.7 degrees to give = be wrong, and still enjoy a top 10 warmest
February.

Average temperatures at all our other climate sites should average
at least a degree warmer than what has occurred through the first
15 days.

Lack of snow cover is partly to blame and goes in tandem with
the primary storm track northwest of our area across the Ohio
Valley-Great Lakes this winter (DJF) as evidenced by above normal
pcpn fm KY northward into the Great Lakes.

Detailing ACY and ABE for February as per PHL data process input.
ACY projects #2 warmest at 41.1F with the record being 41.6F in
1890. The 30 normal is 35.3 or a positive departure of nearly 6
degrees. The projection has 1.2 degrees to give on the down side
for a #9 rank with the POR back to 1874. ACY climate is subject
to radiational cooling which at times may force a colder solution
so confidence on ACY maintaining a #2 projection is less than PHL.
Still, if the pattern doesn`t change significantly from the outlook
of the past two days...it will be a noteworthy top 10 warmest February
on record through most of our Mount Holly forecast area.

ABE projects 7th warmest with a 36.1 average, or 5.4 degrees above
the norm of 30.7. ABE has less room to give on the down side.

NOTE: there has been no talk here of even warmer avg temps since
climatologically the error would favor this projection being
too warm.

Finally...PHL for the winter season (DJF) is projecting an average
of 39.6 degrees...the 9th warmest DJF in the period of record
dating back to 1873-1874. Room to give is 0.4 degrees on the down
side to #10 warmest winter. Essentially its going to take all
of at least a 1.2 degree warm side error to drop back to #10
warmest seasonal average. While this could happen, am thinking
via ensemble guidance that this is unlikely.

Projected seasonal rankings for ACY and ABE follow:

ABE seasonal average temp projects 34.9 or #6 in the POR back
to the winter 1922-23. 0.7 to give to drop out of top 10 so #6
looks pretty solid.

ACY seasonal average temp projects to 39.2 or #12 in the POR
back to the winter 1873-74. .6 to give to drop back to #14.


Past two years: PHL through February 2017 will have recorded above
average temperatures for 22 of the last 23 months. May 2016 was
below normal. Then we have to go back to Jan Feb March 2015 for
below normal monthly temps.



Split flow = no snow was something I heard in Boston and it seems
to apply for the next 10 days as the pattern is devoid of much
phasing of the northern and southern streams.

Change is ensembled sometime between the 25th and the first week
of March with a storm track nearby and a better shot at colder
temps and some winter wx. Because of that i hesitate to look at
seasonal snowfall records. Allentown current #7 least snowy winter
will most likely drop out of the top 10, needing only 1.5" the
rest of the way. PHL ILG are already out of the top 10 least
snowy.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Gale Warning until 11 PM EST this evening for ANZ450>455.
     Small Craft Advisory until 5 AM EST Friday for ANZ430-431.

&&

$$
Synopsis...Kruzdlo
Near Term...Drag
Short Term...Drag
Long Term...Kruzdlo
Aviation...Kruzdlo/Meola
Marine...Drag/Kruzdlo 230P
Climate...



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