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FXUS61 KPHI 222352

Area Forecast Discussion
National Weather Service Mount Holly NJ
652 PM EST Fri Nov 22 2019

High pressure builds in tonight and Saturday morning before 
moving offshore. Low pressure tracks near our coastal areas 
later Saturday night and Sunday morning before moving offshore 
of New England while strengthening through Sunday night. High 
pressure slides to our south Monday and then offshore Tuesday. 
The next cold front arrives Wednesday followed by high pressure 
later Thursday and Friday.


High pressure located in the southern Great Lakes and the Ohio 
River Valley this evening will continue to build eastward 
overnight. We are anticipating a mostly clear sky along with a 
diminishing wind.

Low temperatures are expected to favor the upper 20s and lower 
30s in our region.


By early Saturday, high pressure across our region will quickly
dissipate as low pressure moves from the Tennessee Valley, 
across the Appalachians, through the Mid-Atlantic, then offshore
by Sunday morning. Clouds will increase from southwest to 
northeast by late Saturday afternoon and into the evening hours.
High temperatures should peak in the mid to upper 40s for most,
but may see a few areas in the far south/east reach 50 degrees.

A shield of light to moderate rain will accompany the low as it
moves toward and cross the region. Rain is forecast to move 
into the area by the evening hours and last through much of the 
overnight hours and even into Sunday morning. As the low moves 
offshore, it will be located under the left exit region of its 
parent trough, which will be favorable for rapid 
intensification. As such, expecting the trend of northwest 
banding shown in the latest guidance to continue. This would 
result in the continuation of precipitation well after daybreak 
Sunday and I have updated the forecast to reflect this trend.

As far as precip type goes, there has been a slight warming 
trend in the guidance over the past couple of runs. Therefore, I
increased temperatures a bit across the northwest. As a result,
backed off quite a bit on the wintry precip in the forecast, 
however still expecting some light wintry precip in the form of 
freezing rain, possibly mixing with sleet or snow, overnight 
Saturday night. Lows Saturday night will generally be in the mid
30s to around 40 degrees for most outside of the higher terrain
of the southern Poconos and NW NJ. As the center of the low 
draws near by around daybreak Sunday, temperatures should favor 
precip type to switch back to mostly rain if not already. Could 
see a few snow flakes as the precip ends across the far northern
portion of the forecast area Sunday morning.

The low pressure will move away from the forecast area through 
the remainder of Sunday and skies will clear from west to east. 
Northwesterly winds of 10-15 mph behind the departing system can
be expected with some gusts up to 25 mph. High temperatures 
will be in the 40s to near 50 degrees.


Summary...Turning warmer through the first half of next week 
ahead of a strong cold front then blustery for Thanksgiving day.
Precipitation chances are centered mostly on Wednesday.

Synoptic Overview...A closed low will exit coastal New England 
and move across the Canadian Maritimes Sunday night and Monday, 
then the flow turns more zonal for early next week. A trough 
amplifying eastward from the Plains Tuesday will result in a 
building downstream ridge and warm air advection across the 
East. The aforementioned trough moves across the Great Lakes and
Northeast Wednesday, pulling a strong cold front across our 
region as strengthening low pressure tracks well to our north. 
The trough gradually moves out Thursday as a ridge gets closer 
from the west, and this results in surface high pressure 
building into our region Thursday night and Friday. 

For Sunday night and Monday...Strong low pressure will track 
near Cape Cod Sunday evening then northeastward into Monday. The
flow in its wake in the East tends to turn more zonal into 
Monday, with surface high pressure sliding across the Southeast 
(it extends into our area on Monday). This high then shifts 
offshore Monday night allowing a northwesterly flow at the 
surface to diminish Sunday night into Monday before turning west
to southwest. It will be chilly Sunday night and as the winds 
diminish temperatures could drop off faster during the evening 
especially in the typically colder locales. As the flow backs 
some Sunday night and especially Monday, warm air advection 
starts to increase however this looks more pronounced Monday 
night. This in combination with more of a westerly flow aloft 
may result in some high level clouds starting to arrive. 
Overall, chilly Sunday night and then milder Monday afternoon 
compared to Sunday.

For Tuesday and Wednesday...As an upper-level trough amplifies 
eastward from the Plains Tuesday, a downstream ridge strengthens
surface high pressure off the East Coast. This will result in a
southerly flow across the region with an uptick in the low-
level warm air advection. This will translate to high 
temperatures both days well into the 50's for much of the area 
with some places topping 60 degrees especially Wednesday. Some 
increase in the clouds takes place especially Tuesday night and 
Wednesday, and despite the warm air advection the bulk of the 
lift should remain to our northwest. A surface low will track 
across the Great Lakes Tuesday night and then continue 
northeastward Wednesday, pulling a strong cold front across our 
region during Wednesday. The main forcing may remain just to our
west and north though, with much of the guidance showing not 
much with the cold frontal passage in our area. Given the depth 
of the incoming upper-level trough, maintained chance PoPs 
mainly for Wednesday as the cold front moves through. The 
southerly flow ahead of the front may get a little gusty 
especially in the coastal plain, then gusty northwesterly winds 
in its wake Wednesday night.

For Thursday and Friday...As the Wednesday systems exits New 
England, ridging slides eastward from the Great Lakes to the 
Gulf coast. This will result in high pressure building eastward 
and arriving over our area during Friday. There looks to be a 
tightened pressure gradient in place as low pressure gradually 
moves into the Canadian Maritimes, therefore much of this time 
frame will feature gusty winds (blustery for Thanksgiving Day). 
It looks to be dry though with much drier air advecting across 
the region.


The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, 
KILG, KMIV, KACY and surrounding areas.

Tonight...VFR conditions under a mostly clear sky. Northwest 
wind around 10 knots, diminishing to 6 knots or less and 
becoming west. High confidence.

Saturday...VFR. Increasing high and mid level clouds in the 
afternoon. West wind 6 knots or less backing toward the south as
the day progresses. High confidence.

Saturday night...Conditions lowering to IFR in rain. Southeast 
wind 6 knots or less, becoming northeast around 10 knots. 
Moderate confidence.

Sunday...IFR in rain in the morning. Conditions improving to 
VFR in the afternoon with rain ending. Northwest wind increasing
to 10 to 15 knots with gusts of 20 to 25 knots. Moderate 

Sunday night and Monday...VFR. West-northwest winds diminishing
to 10 knots or less, becoming west to southwest Monday. 
Moderate confidence.

Tuesday...VFR. Light and variable winds becoming south- 
southwest around 5 knots. Moderate confidence.

Wednesday...A period of Sub-VFR conditions and some showers are
possible. Southwest winds 10-15 knots with gusts to 20 knots, 
becoming west to northwest late with gusts to 25 knots. Low 
confidence with the timing of any sub-VFR conditions and wind 


A Small Craft Advisory remains in effect for lower Delaware Bay
until 10:00 PM, and for our ocean waters until 4:00 AM for 
northwest wind gusts around 25 knots.

Winds and seas should gradually diminish late tonight. By 
Saturday, winds and seas are expected to be below SCA criteria 
on all waters.

Sunday night...Northwesterly winds diminish below Small Craft 
Advisory criteria.

Monday and Tuesday...The conditions are anticipated to be below
Small Craft Advisory criteria. Southerly winds start to 
increase Tuesday night.

Wednesday...A Small Craft Advisory is probable. Southerly winds
becoming west to northwest with the passage of a cold front.


MARINE...Small Craft Advisory until 6 AM EST Saturday for ANZ450>455.
     Small Craft Advisory until 10 PM EST this evening for ANZ431.



Near Term...Iovino

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