001 
FXUS61 KPHI 042228
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
628 PM EDT Fri May 4 2018

.SYNOPSIS...
Surface trough is situated ahead of a cold front that will move
across our area tonight. This front will stall to our south, 
and a new area of low pressure will move along this front, 
passing to our southeast on Sunday. High pressure will build in 
behind this system through early next week before another area 
of low pressure moves through the Great Lakes and approaches our
area by the end of next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
The area of showers that moved across eastern Pennsylvania and 
northern New Jersey late this afternoon had all but dissipated 
by 6:00 PM.

Another area of showers was developing from the lower 
Susquehanna River Valley to the Poconos early this evening. It 
should move east northeastward across our region during the 
evening hours. There may be some thunder embedded within the 
area of showers.

A line of heavy showers and thunderstorms extended across 
central New York and western Pennsylvania at 6:00 PM. It was out
ahead of the approaching cold front. The showers and 
thunderstorms are expected to weaken this evening as they move 
into increasingly stable air. If the line of showers and 
thunderstorms holds together, it is anticipated to reach the 
Poconos around 8:30 PM.

Any remaining showers and isolated thunderstorms in our region 
at 9:00 PM should continue to weaken with most of the 
precipitation expected to dissipate by midnight.

The actual cold frontal passage is forecast to take place in 
eastern Pennsylvania and northern New Jersey between about 10:00
PM and midnight. The boundary should work its way across the 
upper Delmarva and southern New Jersey between about midnight 
and 2:00 AM.

Minimum temperatures are expected to range mainly from the 
middle 50s to the lower 60s in our region.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
A secondary cold front moves through the region Saturday 
morning then stalls out over the Mid-Atlantic area. Upper trough
will move through the lower Midwest and into the Tennessee 
Valley and Gulf Coast states and begin to interact with the 
stalled boundary. Surface low pressure develops over the 
Southeast U.S., and some showers begin to lift north into the 
Delmarva and Delaware Valley in the afternoon.

Much cooler and more seasonal temps on tap for Saturday as 
highs will be in the low to mid 70s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Cold front that moves through our area this evening will stall 
to our south. An upper-level trough will aid in the formation of
a new area of low pressure along this front over the Southeast.
Precipitation moves back into the area Sunday morning as the 
low tracks along the East Coast. GFS and ECMWF keep majority of 
the precipitation offshore, but showers are expected to persist 
northwest of the low in much of our CWA through Monday morning.

High pressure moves in behind the low and dominates our weather
through Wednesday. This will provide fair and seasonable 
weather for the first half of next week. 

Another area of low pressure attempts to form along the 
Southeast Coast on Thursday as the high begins to move off to 
the northeast. To the west, an upper-level trough moves across 
the Hudson Bay with a shortwave trough to its south over the 
Great Lakes Region. At the surface, a cold front moves across 
the Midwest with an embedded area of low pressure. This could 
bring the next chance of showers and thunderstorms to our area 
by the end of next week. Temperatures are anticipated to 
gradually warm ahead of this front as the high shifts off to the
northeast.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, 
KILG, KMIV, KACY and surrounding areas.

Tonight...Best chances for SHRA/isold TSRA this evening are for
KRDG/KABE, but scattered SHRA/isold TSRA are possible for I-95 
corridor terminals as well. Brief MVFR/IFR VSBY restrictions are
possible. SW winds diminish to less than 10 kt this evening, 
then veer to the NW after midnight tonight.

Saturday...NW winds less than 10 kt, backing to the west in the
afternoon. Generally VFR. Some showers may move into Delaware, 
Maryland, southern New Jersey, and portions of southeast 
Pennsylvania in the afternoon.

OUTLOOK... 
Saturday night and Sunday: Sub-VFR conditions possible with a 
chance of showers through the period. East to northeast winds 5 
to 15 kts, perhaps with a few gusts to 20 kts on Sunday. 
Moderate confidence. May see some patchy fog near the coast, 
though confidence of this is low.

Sunday night and Monday: May see residual sub-VFR Sunday 
evening before winds become northwesterly by late Sunday night 
and Monday. Some low VFR or even MVFR BKN CIGs may develop on 
Monday as north/northwest winds increase to 10 to 15 kts with 
higher gusts possible. Moderate confidence.

Monday night through Wednesday: Generally VFR with east or 
northeast winds around or below 10 kts, though possibly a bit 
stronger at times near the coast. Moderate confidence.

&&

.MARINE...
A Small Craft Advisory remains in effect as near shore waters 
as winds may gust 25 knots at times through early this evening. 
Farther offshore may have a more difficult time mixing down the 
strong gusts with an inversion over the waters. Additionally, 
seas of 4-6 ft are expected through this evening in the coastal 
waters.

Conditions fall below SCA levels tonight. Sub-SCA conditions 
expected Saturday. 

OUTLOOK... 
Saturday night and Sunday: Sub-advisory conditions expected 
with a chance of showers. Some visibility restrictions are 
possible with the showers, and there is some potential for 
patchy fog on Sunday.

Sunday night and Monday: Seas may build to around 5 feet during
the period with longer-period southeasterly swell developing. 
Patchy fog may develop with onshore flow on Sunday night, but 
winds should switch to northwest and increase on Monday, 
dissipating any fog that is able to develop. There is some 
potential for advisory- level winds Monday. A chance of showers 
with local visibility restrictions and erratic waves/wind.

Monday night and Tuesday: Residual/marginal advisory conditions
possible Monday evening, but winds/seas should subside during 
this period. 

Tuesday night and Wednesday: Sub-advisory conditions expected. 
A slight chance of showers on Wednesday.

&&

.FIRE WEATHER...
Southwest winds should range from around 15 mph with gusts of 
20-30 mph into this evening. Minimum relative humidity values 
are expected to be in the mid to upper 30s through early evening
across southeastern Pennsylvania, southern and central New 
Jersey, eastern Maryland and Delaware this afternoon. So despite
windy conditions this afternoon, an enhanced threat for fire 
spread is not anticipated at this time.

The passage of a cold front tonight will bring a chance of 
showers and thunderstorms as well as cooler temperatures, 
helping to further decrease the fire weather threat. Additional 
shower activity is expected over the weekend.

&&

.CLIMATE...
Below are the daily high temperature records for today, May 4th
at our first-order climate sites:

         DAILY HIGH TEMPERATURE RECORDS:  MAY 4TH 
         ----------------------------------------                           
Site			              Temperature       Year(s) Set
----                          -----------       -----------
Allentown, PA		          92                2001
Atlantic City (Pomona), NJ	  91                1965
Georgetown, DE		          89                1965, 2001
Mount Pocono, PA	          84                1944
Philadelphia, PA	          91                2001
Reading, PA			          90                1913, 2001
Trenton, NJ			          89                2001
Wilmington, DE		          88                1965

Records highs have occurred today at Georgetown and Wilmington.

Over the past two days, a total of 9 additional daily high 
temperature records have been set during this current early 
season heat episode:

Atlantic City-  91 on May 2; 93 on May 3
Georgetown-     90 on May 2; 90 on May 3*
Philadelphia-   91 on May 3 
Reading-        90 on May 3* 
Trenton-        88 on May 2*; 91 on May 3 
Wilmington-     90 on May 3*

(* denotes temperature tied the previous daily record)

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ450>455.
     Small Craft Advisory until midnight EDT tonight for ANZ430-431.

&&

$$

Synopsis...Davis/Staarmann
Near Term...Iovino
Short Term...MPS
Long Term...Davis/Staarmann
Aviation...CMS/MPS
Marine...CMS/MPS
Fire Weather...MPS
Climate...MPS