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FXUS61 KPHI 191315

Area Forecast Discussion
National Weather Service Mount Holly NJ
915 AM EDT Sat Oct 19 2019

High pressure will build to our east later today and tonight. Low 
pressure tracks from the eastern Carolinas later tonight to offshore 
of the Mid-Atlantic coast during Sunday, then it moves out to sea 
into Monday. A cold front moves through our region late Tuesday, 
followed by high pressure Wednesday and Thursday. The next cold 
front should arrive later Friday.


Temperatures will continue to slowly increase through the
morning. Therefore, the frost advisory and freeze warning were
allowed to expire at 9 AM.

Minimum temperatures early this morning dropped to 32 degrees or 
lower for the majority of both Sussex and Warren Counties in New
Jersey, thus, the growing season has ended.

This terminates the Autumn Frost/Freeze Program for these two 
counties. Frost Advisories or Freeze Warnings will no longer be 
issued for both Sussex and Warren Counties for the remainder of 

Otherwise, no significant changes to the forecast with this
update. High pressure centered over central Pennsylvania will 
pass over new Jersey today, and then offshore by the end of the 
period. Abundant sunshine on tap for the day. Return flow sets 
up this afternoon, and temperatures warm up a bit compared to 
Friday. Highs top off in the upper 50s in the southern Poconos, 
and otherwise in the low to mid 60s.


High pressure continues to drift offshore tonight. Meanwhile, 
Tropical Storm Nester will be over the Southeast U.S. this evening, 
and will lift towards the Carolina coast during the overnight hours. 
The significant impacts will remain well to the south of the 
forecast area, but rain will begin to lift into southeast Maryland 
and Delaware towards daybreak Sunday.

With increasing clouds and WAA, lows tonight will be warmer, in the 
low to mid 50s for most of the region, and around 50 in Delmarva.


Summary...Rain associated with current Tropical Storm Nestor moves 
across much of our area Sunday before ending Sunday night. A cold 
front moves through later Tuesday with another cold front arriving 
later Friday.

Synoptic Setup...Amplified flow aloft with a trough ejecting 
into the Plains with another trough from the Great Lakes to the 
Mid- Atlantic Sunday, then ridging builds across the East into 
early next week as a significant trough digs across the Plains. 
This trough shifts eastward through midweek before lifting into 
Canada with some zonal flow in its wake across the northern 
tier. Another trough amplifies into the northern Plains late 
Wednesday, which then shifts eastward through Friday.

For Sunday...Low pressure (remnants of current Tropical Storm 
Nestor) is expected to move northeastward across the eastern 
Carolinas, exiting off the coast near Cape Hatteras during Sunday. 
The low is then forecast to move out to sea during early next week. 
Despite the trough aloft weakening some as it slides across our 
region Sunday, the track of the surface low and ascent to its north 
and northwest side will result in a shield of rain. The highest 
rainfall amounts are expected to be across southeastern New Jersey 
and into southern Delaware. However, much of the guidance brings 
measurable rain to much of region. Based on this and the latest QPF 
forecast from WPC, increased the PoPs north and westward during the 
day Sunday. There will be a period of gusty onshore winds mainly 
along the coast Sunday into Sunday night, and while there is some 
uncertainty with the magnitude some guidance suggests 40-ish mph 
gusts. As of now though, we kept the winds well below advisory 
criteria. The conditions should quickly improve during Sunday night 
from west to east as the system moves far enough away and the flow 
turns more from the north, allowing some drying to work in. 
Temperatures were lowered Sunday across much of the area given 
onshore flow along with clouds and rain. 

For Monday...A sliver of surface high pressure extends southward 
across our area. Any lingering breeze along the coast is expected to 
subside as the pressure gradient collapses due to high pressure 
building in. The return of some sunshine should result in milder 
afternoon temperatures.

For Tuesday...A strong area of low pressure is expected to lift from 
the upper Mississippi Valley and the western Great Lakes Monday and 
into western Ontario during Tuesday. This feature is anticipated to 
pull a cold front through our region late Tuesday. The amplification 
of the parent upper-level trough should result in a slower arrival 
of the cold front. We continue to mention a chance of showers ahead 
of and with the front, however given uncertainty regarding available 
instability held off in adding a thunder mention.

For Wednesday and Thursday...High pressure is forecast to build 
across the southern states Wednesday, then across our region and off 
the coast Thursday. This should have enough of an influence on our 
weather and therefore we anticipate dry conditions.

For Friday...The next cold front arrives later during this time 
frame, although timing is somewhat uncertain. Given the synoptic 
setup that is forecast, there is the potential for a surface low to 
develop along the front as it is crossing our area. If this were to 
occur, the precipitation would be enhanced across our region. For 
now and based on WPC guidance with the front arriving late, kept 
some slight chance PoPs in the gridded forecast.


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

Today...VFR/SKC. LGT/VRB winds this morning, becoming SW less than 
10 kt this afternoon. High confidence.

Tonight...VFR. SW winds less than 10 kt become LGT/VRB after 00Z. 
High confidence.

Sunday...MVFR/IFR conditions probable, especially for PHL/PNE, ILG, 
TTN, MIV and ACY, due to rain and low ceilings. Conditions should 
improve to VFR during the night. East winds 5-15 knots becoming 
northeast, then north at night. At MIV and ACY, winds of 15-20 knots 
with gusts up to 30 knots are possible especially in the afternoon 
and evening. Moderate confidence regarding a period of MVFR or lower 
conditions, but low confidence on the timing and also wind speeds.

Monday...VFR into the evening, then conditions may lower to MVFR or 
IFR during the night with some possible showers especially at ABE 
and RDG. Northeast to east winds 5-10 knots, becoming southeast at 
night. High confidence during the day; low confidence at night.

Tuesday...MVFR/IFR conditions spread across the region through the 
day with showers, then conditions should quickly improve to VFR 
during the night. Moderate to high confidence on conditions below 
VFR, but low confidence on the timing of flight category changes. 
Southeast to south winds around 10 knots, shifting to northwesterly 
at night.

Wednesday...Mostly VFR. Westerly winds of 5-15 knots. Moderate 


Sub-Small Craft Advisory conditions on tap for today and tonight. NW 
winds around 15 kt with gusts up to 20 kt, become around 10 kt this 
morning, then become light and variable this afternoon. Winds 
tonight become S-SE around 10 kt. Seas 2 to 3 ft. 

Sunday...East to northeast winds increase with Small Craft Advisory 
conditions expected in the afternoon and at night. A period of gale 
force wind gusts are possible later Sunday especially south of 
Little Egg Inlet, NJ where a Gale Watch has been issued. Low 
confidence regarding possible gale force gusts in the Lower Delaware 
Bay (around the bay mouth). The seas build significantly especially 
across the Atlantic coastal waters.

Monday...While wind gusts should drop below 25 knots, seas on our 
ocean waters are forecast to remain elevated.

Tuesday...The conditions should be mostly below Small Craft Advisory 
criteria during the day, however a wind shift to northwesterly 
behind a cold front at night may result in a wind surge with gusts 
to around 25 knots.

Wednesday...West or west-northwest wind gusts to around 25 knots 
probable before diminishing at night.


MARINE...Gale Watch from Sunday afternoon through Sunday evening for 


Near Term...Johnson/MPS

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