Scientific Forecaster Discussion
fxus61 kphi 241020
Area forecast discussion
National Weather Service Mount Holly New Jersey
620 am EDT Sat Jun 24 2017
tropical low pressure just west of the Appalachians will lift
to the northeast through the mid-Atlantic and northeast this
morning, and then a cold front will move across the region this
afternoon. Surface high pressure builds into the Midwest as an
upper trough digs into the eastern Great Lakes and northeast
tonight through Sunday. A weak cold front is expected to move
through the region Monday night through Tuesday. High pressure
returns to the area for the middle of next week before moving
off the coast late in the week as low pressure passes north of
Near term /until 6 PM this evening/...
the front with a band of heavy rains and sct tstms is crossing
the Delaware valley attm. Gusts in the 35 knot range have occrd
at kilg recently and can be expected elsewhere with the line.
The heavy showers should last 1-2 hours and produce some
localized poor drainage flooding in a few areas.
Much of the weather action will begin shortly after afd release
with a decent batch of showers and scattered thunder associated
with a front and the remnant moisture from ts Cindy moving
across the area. The warm and tropical airmass in place will
create decent rainfall rates this morning with some 1-2 inch
totals expected thru mid- morning. Once the front crosses the
area, winds will shift to northwest and rapid improvement from northwest to southeast
will progress thru the area. Sunny skies will be across the
region by this afternoon. It will remain very warm, but the
airmass will become drier as the day progresses. Highs will
reach the mid-upper 80s in most areas today. Winds will gust to
20-25 mph for much of the day.
Short term /6 PM this evening through 6 PM Sunday/...
high pressure well to the west will begin to ridge across the
area tonight. Fair weather with mostly clear skies are expected.
Low temperatures will remain in the mid 60s to around 70 in
most areas. The airmass will be much more comfortable tonight
than in recent nights.
Long term /Sunday night through Friday/...
surface high pressure builds into the Midwest and western Great
Lakes Sunday morning. Dry conditions with low humidity on tap
for most of the region, and downsloping westerly flow will push
temperatures into the mid and upper 80s across the Delmarva,
southeast PA, and much of NJ, and in the low to mid 80s for the
Lehigh Valley, Poconos, and northwest New Jersey. Surface dewpoints will
generally be in the 50s. With an upper trough digging through
the eastern Great Lakes and northeast, some shortwave energy
will pass through the base of the trough, and could touch off
some isolated showers and thunderstorms in the afternoon, mainly
over the Poconos.
Conditions dry out Sunday night. Cool and dry with lows in the
50s to low 60s.
Surface high pressure continues to build into the Ohio/Tennessee valleys
on Monday as 500 mb low moves into Great Lakes and upper trough
becomes entrenched over the Great Lakes, northeast, and into the
mid- Atlantic. With shortwave energy rotating around the base
of the trough, some isolated to scattered showers and
thunderstorms are possible, and then coverage becomes slightly
more widespread on Tuesday as the base of the trough and a
surface cold front passes through the region and moves offshore.
Surface high pressure continues to slowly build east through
Wednesday, and then the center of the high moves off the mid-
Atlantic coast by Wednesday night.
For Monday through Wednesday, temperatures will be on the cool
and dry side, with highs generally in the upper 70s to low 80s
to start the week, and then in the low to mid 70s for the mid-
week period. Dewpoints will be in the 50s. Overnight lows will
be in the 50s to low 60s.
With high pressure now off the mid-Atlantic coast, return flow
sets up, and temperatures return back into the mid 80s, and
surface dewpoints creep back up into the low to mid 60s.
By Friday, low pressure moves into the Great Lakes, and some
mid-level shortwave energy spins off ahead of the low, and may
touch off some scattered showers and thunderstorms. Temperatures
once again rise into the upper 80s to around 90, along with
dewpoints in the mid to upper 60s.
Aviation /10z Saturday through Wednesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
A period of poor flying weather thru the mid-morning before a
return back to VFR across the region. Prior to the mid-morning,
showers and isolated thunder with lower ceilings and visibilities expected
across most areas with the remnants of Cindy and a front
affecting the weather. S to SW winds ahead of the system will
swing abruptly to northwest around dawn and gust around 20-25 kts at
times. Later today, clearing and northwest winds backing to west late.
Tonight...VFR, clear skies and light winds expected.
Sunday...VFR. West winds 8-12 knots. Gusts to 19 knots possible in
Sunday night...VFR. Light northwest winds.
Monday...VFR. West to southwest winds 5-10 knots. Isolated
rain showers/thunderstorms and rain possible in the afternoon, mainly north/west of the
I-95 corridor terminals.
Monday night...VFR. Light west winds.
Tuesday...mainly VFR. Sub-VFR conditions possible in scattered
rain showers/thunderstorms and rain in the afternoon.
Tuesday night through Wednesday...VFR.
we will add the Small Craft Advisory flag for Delaware Bay with frequent gusts to 25
knt attm which will likely continue until after the low/front cross
the area this morning. The Small Craft Advisory for the ocean will remain for the day
with seas expected to remain above 5 ft thru the period. Rains and
psbl thunder this morning, then rapid improvement by early
afternoon. Fair weather expected tonight.
Sunday through Wednesday...winds and seas are expected to remain
below Small Craft Advisory criteria. Scattered thunderstorms possible on Tuesday.
today, winds will be shifting off shore, but a 5 to 6 ft swell
may lead to a moderate risk for the formation of dangerous rip
currents. The rip current risk will probably decrease later
today, possibly back to low risk.
Marine...Small Craft Advisory until 6 PM EDT this evening for
Small Craft Advisory until noon EDT today for anz430-431.