Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 231453
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1053 AM EDT Tue May 23 2017

.SYNOPSIS...
A low pressure system will pass to the south and east of our
area tonight, followed by weak high pressure for Wednesday.
Another system develops over the Ohio Valley affecting the mid
Atlantic states late Wednesday through early Friday. Weak high
pressure returns for Saturday with yet another low pressure
forecast to affect the region for Sunday or Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
1037AM update: withdrew shower threat for much of the area today
except Delmarva. Lowered temps several degrees today based on
more cloud cover. Plenty of virga southern part of our forecast
area this afternoon. Confidence on whether it will rain beyond a
trace for our area late today is below average.

Our climate section has some information of use.

A briefing package is being considered for 3 PM to highlight
tidal inundation potential for the Wed-Thu evening high tide
cycles on the Atlantic coasts of DE and NJ, and also less
confidently, a possible QLCS svr wx event late Thursday.

This afternoon...lots of clouds. A brief period of lower clouds
this morning is advecting swwd but its predominantly high cloud
today. How far north the rain late today? Uncertainty but
enough confidence to lower the POPs.

Tonight: Low pressure off the mid Atlantic coast will continue
to slide northeast, with showers possible, especially through
the evening hours for a part of the Delmarva and se NJ coast..
A mid level short wave ridge is expected to build over the ridge
beginning late tonight though. The associated subsidence should
help to bring a quick end to the precipitation after midnight.

&&

.SHORT TERM /WEDNESDAY/...
Wednesday...the coastal low remains to the south and east of our
area and pushes to the northeast fairly quickly. We dry out through
Wednesday and rain looks to hold off for much of the day as weak
high pressure crosses the area.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Wednesday night and Thursday...Low pressure over the Ohio Valley
will move northeast on Thursday. Another low forms along the cold
frontal boundary as it nears our area, and will cross our area later
Thursday.

Rain will start to overspread the region late Wednesday night and
continue through much of Thursday. Marginal instability is noted and
we continue to mention the chance for convection across the area.
With PWAT`s once again rising up around 1.5-1.7 inches, we have the
potential for moderate to heavy rain. With the wet period we have
had of late, we will need to continue to monitor any heavy rain
threat.

Friday...Some showers possible Friday, mainly early and across the
northern half of our forecast area. Overall, it should start to
clear out across our area. Although, a slight cool down can be
expected in the westerly flow.

Saturday...High pressure will build in for Saturday and it should be
a great start to the holiday weekend. A shortwave moves through the
mid levels and across our area Saturday afternoon/evening. This may
spark off a few light showers, mainly across the northern areas.

Sunday and Monday...The rest of the holiday weekend looks unsettled
as another low pressure system develops and heads towards the Mid-
Atlantic. A chance for some showers and/or thunderstorms will be
possible. A cooler day on Sunday with highs only into the low to mid-
70s but warming is expected for Monday, with highs into the upper
70s to lower 80s.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today...A band of MVFR cigs lasting an hour or two was moving swwd
and soon should be a non-factor in the TAFS. Otrw VFR CIGS,
mostly abv 10000 ft. Northeast Wind may gust 15 kt.

Tonight...VFR lowering CIGS with potential MVFR Conds in showers
KACY/KMIV late at night. Northeast wind, may gust 20 kt ACY.

Wednesday...VFR. MVFR/IFR conditions early, mainly at KMIV/KACY.
Easterly winds around 10 knots or less except gusty 15-20 kt at
KACY.


Outlook...

Wednesday night and Thursday...Deteriorating conditions as rain
moves into the area. VFR conditions with periods of MVFR/IFR in
showers/thunderstorms. Easterly winds around 10 to 15 knots
becoming south to southeast around 10 knots or less late.

Friday...Improving conditions with a return to VFR expected. Showers
possible early. West winds around 10 to 15 knots.

Saturday...Mainly VFR conditions expected. West to southwest winds.

&&

.MARINE...
No marine headline today in a general ne flow.

SCA was issued at 1027AM for the DE Atlantic coastal waters
ANZ454-455) tonight into Wednesday.

Outlook...

Thursday and Friday...Seas are expected to build in the
prolonged easterly flow. Small Craft Advisory will likely be
needed. Improving conditions on the waters through Friday as
seas start to subside and winds diminish.

Saturday...Both winds and waves are expected to stay below SCA
criteria.

&&

.HYDROLOGY...
After rain amounts over 3 inches in some places across south
Jersey yesterday, levels for many creek and rivers on the
coastal Plains were slowing their rises or receding. At this
time, all remain below bankfull and flood stages, but we continue
to monitor this area. Models have trended further southeast and
later with heavy rain today. Thus, though these areas will
likely see additional rain late today, we are expecting
generally light rain amounts (near or below one quarter inch).

A wet pattern looks to continue for much of the week. The next
period of heavy rain could come as early as Wednesday night into
Thursday.

&&

.TIDES/COASTAL FLOODING...
The plan is to probably issue a briefing package around 3 PM this
afternoon for multi high tide cycle advisory potential, beginning
Wed evening through Thursday evening, including possible Watch-
moderate potential for the Sandy Hook related tides Thursday
evening.

Some of the highest astronomical tides of the year are occuring
late this week. The new moon cycle on Thursday, combined with a
possible prolonged easterly flow, we will probably see some of
our coastal sites exceed minor tidal flooding levels during the
Wednesday and Thursday evening tide cycles. There is also a
small chance that we could reach moderate levels in a few spots.

&&

.CLIMATE...
ACY is #6 wettest May on record with its 6.07. The record there for
May is 8.80 set in 1948....POR back to 1874.

Monthly avg temps should end up within .7 degrees of where they
are now, possibly edging on the warmer side of the current
departures as seen in our climate data ending the 22nd.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from midnight tonight to noon EDT
     Wednesday for ANZ454-455.

&&

$$
Synopsis...Meola
Near Term...Drag 1053
Short Term...Drag/Johnson
Long Term...Meola
Aviation...Drag/Johnson/Meola 1053
Marine...Drag/Johnson/Meola 1053
Hydrology...1053
Tides/Coastal Flooding...1053
Climate...1053



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