Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 300140

Area Forecast Discussion
National Weather Service Mount Holly NJ
940 PM EDT FRI JUL 29 2016

Scattered showers and thunderstorms with locally heavy rainfall
will re-develop Saturday afternoon and linger into Monday with low
pressure and a frontal boundary hung up across the mid Atlantic
States. High pressure will then bring mainly dry and less humid
weather for the remainder of the next work week.


930 PM ESTF: used the hrrr as the primary guidance through 06z
advancing showers south through e PA and w NJ down to KILG around
05z. eventually these heavy showers (no thunder so far all evening)
should dissipate, though dissipation may delay later than now

There is instability and weak low lvl convergence, especially
near the Delaware River. Then dry overnight (after 1 or 2 am).

Winds will be light. This, combined with the recent heavy rainfall
across portions of the region means we could see patchy fog,
especially across the axis of heaviest precip in northern Delmarva,
the Pine Barrens and parts of the area along and north of I-78.
added dense fog to nw NJ and e central PA. An SPS for dense fog
may eventually be needed across parts of our fcst area.


The upper level trough becomes more defined as it moves closer to
the region. As a result, should see an area of precipitation move
into the region (exact timing is uncertain by the higher chances
look to be in the afternoon). As far as hazards, the primary hazard
appears to be heavy rain. Precipitable water values are well above
normal, and storm motions look to be quite slow (<15 kts) as the
flow is weak. However, with limited focus for surface convergence
(at least over our immediate area), not confident that there will be
a widespread flooding threat. Thus, not planning to issue a flash
flood watch at this time.



* Scattered showers and thunderstorms Saturday night/Sunday with the
  potential for heavy rainfall and a very localized flood threat

* Scattered showers/thunderstorms linger Monday, otherwise much of
  the next work week will be dry and less humid


Saturday night and Sunday...

A couple of additional shortwaves will move across our region along
with a frontal boundary in the vicinity.  The result will be periods
of scattered showers and thunderstorms Saturday night into Sunday.
Specific timing is uncertain at this point, but Pwats of 2+ inches
will bring the potential for locally heavy rainfall.  While any
flood threat looks very localized, weak low level wind fields may
result in slow movement and back building of any thunderstorms,
so that will need to be watched. Weak wind fields will also result
in a low overall risk for severe weather, but a few strong storms
can not be ruled out.


Guidance has trended a bit slower over the past 24 hours.  Frontal
boundary will still be across our region along with another piece of
shortwave energy moving in on Monday. The result will be the
continued chance for scattered showers and thunderstorms.

Tuesday Through Friday...

Large high pressure will be building across the mid Atlantic States.
While we can not rule out a few lingering showers Tuesday, mainly
dry and less humid weather is expected through Friday.  High temps
will mainly be in the 80s for much of the next work week.


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

Tonight...VFR with sct clouds aoa 6000 ft. Showers lingering
longer than expected and these may not dissipate until reaching
the vicinity of Philadelphia around 1130 pm or midnight. Light
wind becoming calm with a chance of patchy fog nw NJ and in the
seabreezed areas of coastal NJ and coastal DE.

Saturday...cirrus ceilings lower to sct-bkn aoa 3500 ft during
the afternoon with showers and isolated tstms with heavy rain
spreading newd. showers could begin to move into the western TAF
sites (KABE, KRDG) after 15Z and Delaware Valley TAF sites (KPHL,
KPNE, KILG, and KTTN) after 18Z. east or southeast wind.


Saturday night through Monday...Moderate to high confidence.
VFR dominates but periods of lower conditions expected in
scattered showers and thunderstorms.

Tuesday and Wednesday...Moderate to high confidence in mainly VFR


Winds and seas should remain below SCA criteria through Saturday.
Mainly variable winds overnight becoming predominantly southeast

Outlook...Saturday night through Wednesday...A wave of low
pressure may result in a brief period of marginal small craft
advisory seas across our northern waters Sunday afternoon/early
evening. Otherwise, weak pressure gradient should keep winds/seas
mainly below small craft advisory thresholds through Wednesday.
Main concern for mariners will be the threat of scattered
thunderstorms Saturday night through Monday.

Rip Currents...The probability for the development of dangerous
rip currents on Saturday is low. Sunday may become a moderate risk
along parts of the central and northern NJ shore, dependent on the
strength of the onshore flow. A longer period 2 to 3 foot se swell
may develop around Wednesday August 3.


PHL: heading for top 8 warmest July on record. July avg temp for
PHL will be about 80.9 or 81.0F, 8th warmest July in the period of
record since 1874. if its would be tied for 7th.

ACY: 8.77 inches as of 5 PM ranks 6th wettest July on record with
its monthly record of 13.09 set in 1959. The por is back to 1874.

1959 13.09
1969 12.64
1958 10.92
1945 10.22
1903 10.14
2016 8.77

ACY entire July normal rfall 3.72

Still opportunity for ACY to rise in the monthly rainfall ranking,
though WPC has only about .75 for the rest of the month.




Synopsis...Drag/99 940
Near Term...Drag 940
Short Term...Drag/Johnson
Long Term...99
Aviation...Drag/99 940
Marine...Drag/99 940
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