Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 230726
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
326 AM EDT TUE AUG 23 2016

.SYNOPSIS...
High pressure over our area today and tonight will shift offshore
Wednesday. A weak cold front is forecast to move through during
Friday, then high pressure builds in Saturday into Sunday before
shifting off the New England coast later Sunday into Monday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pressure will be in control of the weather today. Mostly clear
conditions with only a few clouds are expected today. Temperatures
will be a few degrees warmer than Monday, and end up a couple
degrees warmer than normal. Humidity levels will remain low as
dewpoints remain low today. Precipitation chances today are zilch.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
High pressure remains in control of the weather tonight, keeping
mostly clear skies across the area. Overnight lows will likely end
up a little warmer than Monday night as thicknesses begin to
increase. It is also possible that some patchy fog may develop as
temperatures cool and calm/light and variable winds develop again.
Precipitation chances remain nil.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The synoptic setup is comprised of a ridge across the southern
states that expands into the Mid Atlantic region Thursday into
Saturday. This ridge may then retreat back to the southwest some
later in the weekend and early next week as a short wave trough
tracks across the Midwest and into the Great Lakes region. This will
result in building heat and humidity for the end of the week. We
used a model blend for Wednesday into Friday, then blended in mostly
the 00z WPC guidance with continuity thereafter. Some adjustments
were then made following additional collaboration with our
neighboring offices.

For Wednesday and Thursday...As a ridge remains centered across the
southern states, it begins to expand north-northeastward into the
Mid Atlantic especially Thursday. As this occurs, surface high
pressure slips offshore Wednesday and then farther out to sea
Thursday. This will result in a return flow, however the main
moisture advection looks to take place on Thursday. As a result, a
warm afternoon Wednesday however dew points are expected to be in
the comfortable range overall. The dew points then creep up some
Thursday across much of the area. The flow looks to be light enough
both days where a sea breeze develops and therefore it is possible
that dew points increase in the wake of this boundary especially on
Thursday. A lee-side trough may develop Thursday however it appears
some initial convection develops to our west as enough subsidence
from the southern states ridge mainly dominates much of our area.
Some isolated convection however may move into our western zones
Thursday evening as moisture/thermal advection increases some,
therefore carried a slight chance pop.

For Friday and Saturday...Our area looks to be on the northern
periphery of a large southern states ridge. Some short waves
traversing the westerly flow aloft from the Great Lakes to the
Northeast may be enough to spark some diurnal convection. A lee-side
trough looks to be in place Friday ahead of a weak cold front,
therefore both of these features may focus just enough surface
convergence for some convective development. The overall forcing
looks weak with mostly the northern areas more removed from
lingering subsidence of the ridge. As a result, we will continue to
indicate slight chance pops Friday. It will be hot and much more
humid Friday ahead of the weak cold front, however heat indices are
anticipated to be below advisory criteria. The weak front looks to
be offshore Saturday with high pressure starting to build in from
the northwest. While a temperature drop should occur Saturday in the
wake of the weak front, more of a dew point drop should be more
noticeable for much of the area.

For Sunday and Monday...High pressure builds across the Northeast
into Sunday before it slides off the New England coast by late
Sunday. As the high weakens or separates into two Monday, a short
wave trough is forecast to be migrating across the Midwest to the
Great Lakes. This should result in a warm frontal type feature
developing into the Ohio Valley Monday. A ridge axis is forecast to
be to our west, with a bit of a trough across the Northeast. Some
guidance shows either some weak short wave forced convection Monday
or terrain influenced. Given the timing uncertainty along with
questions regarding the forcing mechanisms, maintained some slight
chance pops for portions of the area Monday.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

VFR conditions will continue today and tonight as high pressure
affects the area. Patchy fog may affect a couple of airports, mainly
RDG which may drop into MVFR range. Winds will generally be 5-10
knots or less today, before becoming calm/light and variable again
overnight.

Outlook...
Wednesday and Thursday...VFR. Winds should favor a south to
southwest direction at less than 10 knots, however turn more
southeasterly each afternoon at ACY/ILG due to a sea/bay breeze.

Friday...VFR overall. A few isolated showers/thunderstorms are
possible as a weak cold front moves through.

Saturday...Mainly VFR.

&&

.MARINE...
The pressure gradient will weaken today as high pressure will move
across the waters today and tonight. Winds will lighten through
today and into tonight and remain well below Small Craft Advisory
levels.

Outlook...
Wednesday through Saturday...The winds and seas are anticipated to
be below Small Craft Advisory criteria. However, a southerly flow
should increase for a time Wednesday and Thursday especially in the
afternoon and evening with some enhancement from sea/bay breeze
circulations. A weak cold front moves through Friday with a wind
shift to the northwest, then more north-northeast Saturday.

RIP CURRENTS...
For today, the risk for the formation of dangerous rip currents looks
to be low.

For Wednesday, the probable risk for the formation of dangerous
rip currents is low. However this may increase to moderate,
especially for the New Jersey beaches, especially if the wind
turns more southeasterly as it increases some in the afternoon.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$
Synopsis...Gorse
Near Term...Robertson
Short Term...Robertson
Long Term...Gorse
Aviation...Gorse/Robertson
Marine...Gorse/Robertson



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