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000
FXUS61 KPHI 270721
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
321 AM EDT Thu Jun 27 2019

.SYNOPSIS...
As high pressure across the southern states expands northward
across the Mid-Atlantic region through Friday, a weak front
settles into our area. Low pressure tracking to our north
Saturday will pull a cold front across our area later Saturday
before settling to our south Sunday. High pressure builds in for
Monday, then a weak cold front arrives late Tuesday into
Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A broad area of high pressure will influence much of the
country east of the Mississippi River for today. We are
expecting mostly sunny and warm conditions.

Maximum temperatures are forecast to be slightly higher than
those on Tuesday. Dew point readings are expected to be around
60 in the afternoon, so heat index values should be near of
slightly below the actual air temperatures.

A light northwest to west wind is anticipated. However, the sea
breeze front should make some progress inland during the
afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
High pressure will continue to bring a mainly clear sky to our
region for tonight. The wind is forecast to be light and
variable with low temperatures favoring the range from the
middle 60s to the lower 70s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Summary...Hot and becoming more humid through Saturday, then
some temporary cooling and lower dew points Monday. The heat and
humidity should build again during the first half of next week.
Some showers and thunderstorms over the weekend, then again
Tuesday into Wednesday with a weak cold front.

Synoptic Overview...A strong ridge across the southern states
builds northward across the Plains and into south-central Canada
Friday into Saturday. Meanwhile, a closed low centered near
Hudson Bay Friday is forecast to shift southeastward and across
the Northeast during the weekend. Prior to the troughs arrival
in the Northeast, a hot airmass continues for our region and dew
points will be on the rise especially for Saturday. The trough
should push a weak cold front across our area by later Saturday,
which will result in cooler and less humid air on Monday. The
heat and humidity then should build Tuesday and Wednesday.

For Friday...Our area will remain on the southern edge of the
westerlies. A closed low centered near Hudson Bay Canada will
gradually amplify/spread southeastward. A short wave on the
south side of this closed low will be responsibly for some
convection across the Great Lakes region. Nearly all of this
activity looks to remain to our northwest. A few isolated
showers/thunderstorms though may develop to our west during peak
heating and mainly tied to terrain influences (lee-side
trough). We therefore bring in some slight chance PoPs mainly in
the evening across the far northern zones and parts of eastern
Maryland. It will be another hot day for the majority of the
region, with temperatures topping out in the upper 80`s to low
90`s. A southwesterly flow looks light and therefore a sea
breeze front should develop starting around midday. This will
keep the coastal locales cooler. While the surface dew points
will be a little higher than Thursday, enough drier air above
the surface should help to keep the dew points low enough during
daytime heating. As a result, the maximum heat indices are not
expected to be much higher than the air temperatures.

For Saturday and Sunday...As an upper-level trough overspreads
the Northeast, surface low pressure tracks to our north Saturday
with an associated weak cold front crossing our region by later
in the day. This front is forecast to be clearing our southern
areas early Sunday morning. On Saturday, temperatures should be
at or a little above Friday`s however dew points will be near
70F in advance of the front. Assuming convection holds off long
enough, the combination of the hot temperatures and higher dew
points should result in peak heat indices Saturday afternoon
approaching 100 degrees in Delmarva and along the urban I-95
corridor. Some showers and thunderstorms are anticipated to
accompany the cold front, however coverage is less certain.
Strong northwest flow aloft along with ample instability may
result in some robust convection Saturday with locally strong
wind gusts possible especially if enough organization can occur.
Some strong convection may occur Sunday as well given the
passage of the trough axis and a strong shortwave. This will be
refined as we get closer and resolve the timing and forcing
mechanisms better. Despite the cold front clearing our area to
start Sunday, the passage of a strong shortwave with the upper-
level trough axis should result in some additional showers and
thunderstorms.

For Monday and Tuesday...A strong trough is forecast to be
moving away from the Northeast Monday with weak high pressure
building in. Temperatures should be seasonably warm Monday as
the trough and associated cold pool pull away. High pressure to
our south Tuesday should result in a more south to southwest
flow, allowing warmer air to once again overspread the area. As
a result, some areas will make a run at 90 degrees Tuesday
afternoon. A trough sliding across New England should send a
weak cold front across our area Tuesday night with the potential
for some convection.

For Wednesday...Our region remains within nearly northwest flow
aloft with a ridge axis to our south and west. Some mid level
shortwaves embedded within the northwest flow aloft may still
trigger some convection despite a weak cold front settling to
our south. There does not look to be much of an airmass change,
therefore more hot weather is anticipated.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today...VFR with few clouds. Northwest to west wind 4 to 8
knots. The sea breeze front will likely reach KACY early in the
afternoon resulting in a wind shift to the southeast at that
location.

Tonight...VFR with few clouds. Variable wind 6 knots or less.

Outlook...
Friday...VFR. Light and variable winds becoming southwesterly
around 5 knots, however becoming south or southeast at ACY due
to an anticipated sea breeze.

Saturday and Sunday...Some showers and thunderstorms around
especially each afternoon and evening, which will result in
local and brief MVFR/IFR conditions. Southwest winds Saturday
around 10 knots becoming west to west-northwest and then
continuing Sunday.

Monday...VFR. Northerly winds 5-10 knots, potentially becoming
light and variable by late afternoon.

&&

.MARINE...
A westerly wind less than 10 knots this morning should become
variable toward midday, then southerly in the afternoon. The
wind is forecast to go back to the west tonight.

Waves on our ocean waters and on Delaware Bay will be 2 feet or
less.

Outlook...
Friday and Saturday...The conditions are anticipated to be
below Small Craft Advisory, despite a southerly wind increasing
some which then becomes west to west-northwest late Saturday.
Some showers and thunderstorms are anticipated on Saturday
afternoon and evening.

Sunday and Monday...West to northwest winds Sunday becoming
north Monday, however the conditions are anticipated to be below
Small Craft Advisory criteria.

Rip Currents...
The wind direction is forecast to be westerly this morning,
becoming onshore for this afternoon. Speeds are expected to be
10 MPH or less. Breaking waves should be 2 feet or less. As a
result, there is a low risk for the development of dangerous rip
currents for today.

For Friday, a low risk for the development of dangerous rip
currents is anticipated with southerly winds around 10 mph and
waves (6-9 second period) in the surf zone of 1-2 feet.

&&

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

&&

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