Area Forecast Discussion
Issued by NWS Mt. Holly, NJ-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KPHI 230941
Area Forecast Discussion
National Weather Service Mount Holly NJ
541 AM EDT Sun Oct 23 2016
The next cold front will slide through our region late tonight into
Monday morning. A high, currently over central Canada will build
south towards our region through mid week. A warm front, followed
quickly by another cold front is expected in our region at the end
of the week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pres will build in from the s today. As it does, strong low
pres will remain in place over ern Canada. The pgrad between these
2 sys will cause gusty nw wind again this aftn, but not as strong as
Overall, a dry and more pleasant day is in store with high temps
mainly in the 50s n and w and 60s elsewhere.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
A weak disturbance will move acrs nrn areas tonight. This feature
will bring some showers, but any rain will be over with before
daybreak. The vast majority of the guid keeps precip confined to
nrn sections, while the ECMWF wants to bring it a bit further s. For
now will go with the more nrn soln.
.LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --Monday and Tuesday...models have sped up the development of the
northwesterly flow pattern, and thus the cold air advection.
Therefore, expect a bit of a cooling trend with highs tomorrow,
and then even more pronounced on Tuesday. Monday night begins what
will likely be the first of several nights with frost/freeze
potential for much of the area where the growing season continues.
With another day of cold air advection, and even better
radiational cooling conditions, Tuesday night looks to be even
colder, with a freeze likely for much of southeastern PA (with the
exception of the Philly metro area), and the remainder of NW NJ.
Wednesday...as the high moves closer, flow shifts more northerly,
but still quite cool with highs about 10 degrees below normal.
There will be another risk for freeze on Wedensday night. However,
unlike Tuesday night, increasing clouds late may somewhat limit
radiational cooling. If the clouds come in early enough, this
could inhibit frost development. For now, kept a mention of patchy
frost for areas with a forecast min of 36 degrees or less, but may
have to adjust both the min temp forecast and mention of frost if
the trend continues with low and mid level clouds moving in before
Thursday and Friday...Models came into much better agreement with
the track of the extra tropical low lifting across the Great Lakes
region and into Quebec through this time. However, there remain
some timing differences, with the GFS being the more progressive
solution, while the ECMWF and CMC are slower. Still, with this
track, it looks like a warm front will lift through our region
sometime on Thursday. Within the warm sector, we should see
increasing chances for precipitation across the region. Then, a
cold front should sweep through the region on Friday.
Those are the factors that the models agree on. However, the GFS
is depicting a mid level short wave trough lifting through the
region ahead of the warm front on Thursday morning, providing
enough lift for some pre frontal precip. This is significant
because GFS model soundings across the Poconos indicate that if
this does happen, it could be a rain/snow mix. However, it is a
very small chance especially considering that neither the CMC and
ECMWF are depicting this and there would be limited opportunity
for moisture advection ahead of the front. For now have only
mentioned a chance of rain and snow across the Poconos through
Thursday morning, before switching precip to all rain.
Saturday and Sunday...models are depicting the cold front stalling
near or just south of our Delmarva counties. However, this seems
unlikely given the upper level northwesterly flow pattern.
Thus...have kept the forecast dry beyond Friday.
-- End Changed Discussion --
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
VFR conds are expected thru the TAF pd, with high pres genly in
control. A weak disturbance will move acrs nrn sections tonight and
bring some SHRA, but precip shud be light enough that no impacts to
cigs or vsbys are expected. Dry conds are expected again by
A gusty nw wind is expected again this aftn, but it will not be as
strong as on Sat. Gusts to 25 kt are psbl, with wind subsiding to
10 kts or less after sunset.
Monday through Wednesday...mostly VFR conditions expected.
Wednesday night and Thursday...ceilings should lower through the
overnight hours to MVFR (with possible localized IFR) by mid day
Thursday. Visibility restrictions possible with rain showers later
in the day.
The gale warning on upper Delaware Bay has been dropped and replaced
with a SCA which is in effect until 21Z. For lower Delaware Bay,
gusts around gale criteria keep occurring, so the GLW remains and
has been extended. The gale warning remains in effect on the Ocean
waters. The only change is that zone 453 has been added to the
later expiration time.
Monday and Tuesday...SCA conditions are expected to continue as
winds should continue gusting above 25 kt (though seas may drop
off below 5 ft.
Wednesday and Thursday...winds and seas should stay below SCA
Thursday night...winds could increase above SCA criteria on the
coastal waters late.
MARINE...Gale Warning until 6 PM EDT this evening for ANZ450>452.
Gale Warning until noon EDT today for ANZ431-453>455.
Small Craft Advisory until 4 PM EDT this afternoon for ANZ430.