396 
FXUS61 KPHI 081750
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1250 PM EST Fri Feb 8 2019

.SYNOPSIS...
Intense low pressure will track across central Quebec this 
afternoon, pulling a strong cold front farther off our coast. 
High pressure builds in later Saturday before moving offshore, 
however a stronger high builds to our north Sunday through 
Tuesday. A weak area of low pressure moves through Sunday night 
into Monday, then a stronger low pressure system follows for 
Tuesday into Wednesday with high pressure returning for 
Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The cold front was pushing off our coast at midday, with 
clearing building overhead from the west. The west wind was 
increasing to 15 to 25 MPH. Gusts of 30 to 40 MPH are expected 
for this afternoon.

Maximum temperatures were likely occurring just behind the cold
front as the passing of the boundary mixed the atmosphere. 
Readings should reach the upper 50s and lower 60s from 
Interstate 95 southeastward. Highs should be in the upper 40s to
the middle 50s in areas to the northwest. Temperatures will 
likely drop slightly during the afternoon with the more 
substantial cold air not arriving until after dark.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
Dry conditions tonight behind the front. Skies should clear 
rather quickly as drier air moves into the region. It will 
remain windy with northwest winds of 15 to 20 MPH and gusts of 
30 to 40 MPH. Less frost development overnight with these winds,
however. It will be the coldest night we've seen in awhile with
overnight lows ranging from the low teens across the southern 
Poconos to the mid 20s across southern Delaware.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Summary...Colder over the weekend with a weak system bringing 
some wintry precipitation Sunday night into Monday. Rather 
unsettled for the first half of next week, with the potential 
for a wintry mix or snow to rain Tuesday into Wednesday. Drier 
weather is anticipated for Thursday.

Synoptic Overview...A strong upper-level trough is forecast to 
exit the Northeast and eastern Canada Saturday into Sunday, 
although another trough swings across eastern Canada during 
Sunday. Meanwhile, a significant upper-level trough across the 
West will eject pieces of energy eastward within the southern 
stream. As this occurs, a strong ridge from the Gulf of Mexico 
eastward remains in place through early next week. The initial 
split flow sends a quick but weak system across our region 
Sunday night into Monday, then strong energy sliding across the 
Plains and Midwest drives a deepening surface low to our 
northwest early in the week with the potential for redevelopment
in the vicinity of the Delmarva coast. As this occurs, cold 
surface high pressure centered in eastern Canada looks to setup 
a wedge into the northern Mid-Atlantic. This all offers the 
potential for a couple rounds of wintry precipitation, but the 
details are less certain at this time.

For Saturday and Sunday...Northwesterly winds remain gusty at 
least through early Saturday afternoon, although not as strong 
as Friday. However, by late Saturday afternoon the winds 
diminish as high pressure moves into the eastern Great Lakes and
the pressure gradient relaxes. Despite a lack of clouds it will
be seasonably cold with high temperatures mostly in the low to 
mid 30s (except 20s over the Poconos). Low wind chills Saturday,
then much less wind Saturday night and Sunday. As the winds 
drop off Saturday evening, a lack of clouds and a very dry 
airmass, temperatures should drop rather quickly with much of 
the area down into the teens.

On Sunday, high pressure will slowly drift offshore leading to 
increasing clouds especially in the afternoon as the next system
approaches from the west. However, any precipitation looks to 
hold off at least through the daylight hours. As the high moves 
offshore, a light southwest flow will allow temperatures to 
moderate some. 

For Sunday night through Thursday...The pattern does not look 
to change too much as and upper-level trough will tend to 
dominate over the central and western U.S. with ridging in the 
western Atlantic. This will result in a tendency for the 
dominant storm track to remain right along the coast or inland 
generally favoring rain or mixed precip events over all snow 
events. Also, after a reprieve over the weekend the pattern does
look to become more active through the first half of next week.

An initial weak disturbance moves through Sunday night into 
Monday bringing light precipitation, mostly in the form of snow 
but a rain/snow mix should occur over parts of Delmarva and 
southern New Jersey. While amounts are anticipated to be on the 
light side, there is some uncertainty on the northern extent of 
the precipitation shield. This system will have to be watched 
especially given an overrunning setup, which can over perform 
sometimes. This system should quickly shift offshore by late 
Monday with high pressure moving across to our north. Conditions
should stay mainly cloudy though with temperatures near 
average.

A much stronger and moisture laden system then looks to move 
northward from Texas towards the Great Lakes by later Monday 
night into Tuesday. Considering this is still several days out, 
the guidance is in relatively good agreement on this so the PoPs
are on the higher side (likely). The precipitation types are a 
challenge, especially since a secondary low may develop right 
along or just off the coast which could keep cold air (at least 
in the low levels) in place longer. This could be another mixed 
precipitation event for Tuesday with snow changing to rain 
across a good portion of the area and even a period of a wintry 
mix or icing during the transition. The details are rather 
uncertain given the setup and evolving thermal profiles at this 
time range, therefore the forecast includes most types of 
precipitation as derived by a model blend mostly from a partial 
thicknesses approach. The pattern though looks to remain 
progressive so the system should be moving out by early 
Wednesday with drier conditions to follow by late Wednesday into
Thursday.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, 
KILG, KMIV, KACY and surrounding areas.

This afternoon...Clearing with VFR conditions. West wind 15 to 
20 knots with gusts of 25 to 35 knots.

Tonight...VFR under a mostly clear sky. West northwest wind 10 
to 20 knots with gusts of 25 to 30 knots.

Outlook... 
Saturday and Sunday...VFR, although clouds increase later 
Sunday. Northwest winds 10-20 knots with gusts to around 25 
knots Saturday, diminishing Saturday night, then light 
southwesterly Sunday. 

Sunday night and Monday...MVFR conditions should develop, 
possibly IFR, with light snow or a rain/snow mix Sunday night 
into early Monday. Lingering low ceilings through Monday. Light 
winds overall. Low confidence on the northern extent of the 
precipitation. 

Monday night and Tuesday...MVFR or lower conditions probable 
with snow or mixed precipitation possibly changing to rain for 
some areas.

&&

.MARINE...
Small Craft Advisory continues through 23Z. West winds this 
afternoon at 15 to 20 knots with gusts of 25 to 30 knots. Some 
gusts above 35 knots will be possible this evening and into the 
overnight, thus have kept the Gale Warning in place. Seas from 
2-4 feet will build to 3-5 feet by this afternoon and into the 
overnight.

Outlook... 
Saturday...Gale Warning through 18z with gusts to around 35 
knots, then the winds diminish in the afternoon and especially 
at night. 

Sunday and Monday...The conditions are anticipated to be below 
Small Craft Advisory criteria.

Monday night and Tuesday...Winds and seas on the increase with 
a Small Craft Advisory looking likely.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ430-
     431-450>455.
     Gale Warning from 6 PM this evening to 1 PM EST Saturday for 
     ANZ430-431-450>455.

&&

$$

Synopsis...Gorse
Near Term...Iovino
Short Term...Davis
Long Term...Fitzsimmons/Gorse
Aviation...Gorse/Iovino
Marine...Davis/Gorse