Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 230552
Area Forecast Discussion
National Weather Service Mount Holly NJ
152 AM EDT Fri Sep 23 2016
A cold front will move south across the area tonight and Saturday
morning. High pressure will build across the northeast United
States over the weekend into early next week. A warm front is
expected to lift north of the area around Tuesday, while a cold
front remains to our west.
.NEAR TERM /THROUGH TODAY/...
Early this morning...clear cool and calm most of the area with
spotty countryside fog. Exception: low clouds will hug the southeast
NJ coast and much of southern DE. coolest temps will be in the upper
40s to around 50 in nw NJ and ne PA where radiational cooling occurs,
per the continued 2m temp fcst of the 00z/23 GFS (am really liking
the GFS 2m temp data for radiational cooling mins in the countryside
and then adding 3-4F to the max 2M temp at 18z for max temps on partly
to mostly sunny non-marine influenced days).
Today... Sunny and very warm with max temps 88 or 89 in PHL/ABE and
mid-upper 80s elsewhere. MAX temps may occur today between 4 and
5PM when the BL temp is warmest. winds become light west. Max
temps are forecast generally 10-15F above normal but below record.
Wont be surprised at isolated 90F this afternoon at the typically
hotter I-95 spots.
Forecast basis is a 50 50 blend of the 00z/23 gfs/nam mos except
as noted which in this case...raising guidance max temps based on
GFS2m temp of 85 at 18z and an expected 17C at 850MB.
.SHORT TERM /TONIGHT/...
Cold frontal passage from north to south. Have doubts about CFP
passage prior to 6 AM fm KESN to KGED southward. Low or mid clouds
and a briefly gusty ne wind to 20 mph accompany the CFP. It`s
possible the max temp for the calendar day of Sept 24 will occur
at 1 am in a few spots around PHL (74-75F). Small chance of a shower
or isolated tstm near and north of I-78 this evening. NCAR WRF
(00z/23) confused display this evening and SPC WRF so far hasnt run.
pwat 1.4-1.5 inches this evening dries to .5 inches I80 north by
morning so that mins kmpo to KFWN and KMPO may again be near 50.
Forecast basis:50 50 blend of the 00z/23 gfs/nam mos guidance.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
High pressure will build across the northeast over the weekend
and into Monday of next week. This will bring cooler weather to
the area, along with dry conditions.
There are differences between the GFS and ECMWF as we move into
Tuesday, as the GFS lifts a warm front through the area, while the
ECMWF moves a cold front across the area. We decided to stay
closer to WPC and continuity. This would keep the cold front to
our west through the end of the week, before it possibly reaches
the area Thursday into Friday. There will remain a slight chance
of showers each day from Tuesday through the end of the week,
although it will only be 20 percent at this time.
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Early this morning...cigs 700-1500 ft vcnty KACY and KMIV with
VFR conditions elsewhere. calm or light north wind.
Today....VFR few cirrus with the wind becoming west or southwest
this afternoon around 5 to 10 kt.
Tonight...VFR to start then sct-bkn layers aoa 2500 ft spread southward
with a wind shift to ne and gusty to 20 kt for an hour subsequent
to a cold frontal passage. There is a slight chance of rain
showers with the front at KABE and KTTN late but not in the TAF
attm due to low confidence.
Saturday-Tuesday...VFR conditions expected.
No marine headlines today. We may need an sca for ne wind gusts 25
kt in ANZ450-51 and seas building to 5 ft there late tonight.
Otherwise winds becoming westerly for a time today (after sunrise) then
south southwest this afternoon (sea breeze influence) before shifting
light northwest this evening and then north northeast gusty to at
least 20 kt behind the cold frontal passage early Saturday morning.
Saturday...Conditions may approach Small Craft Advisory levels.
Winds may gust around 20 to 25 knots at times behind a cold frontal
passage into Saturday morning. Seas should build to 4-5 feet during
the day Saturday.
Saturday night-Tuesday...Sub-Small Craft Advisory conditions
expected through. Winds may gust around 20 knots at times.
The probable risk for the formation of dangerous rip currents
today is low.
Weekend...There is a chance of a moderate risk for the formation of
dangerous rip currents on at least one of the weekend days, as a 3
to 4 foot east-southeast swell from Tropical Cyclone Karl arrives
along with a gusty northeast wind. Karl`s lack of development may
result in a lower swell which would help reduce the potential
risk for the formation of dangerous rip currents.
Will update the previous morning climate JAS discussion with new
reality and forecast data. No major changes anticipated.
Near Term...Drag 152a
Short Term...Drag 152