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633
FXUS61 KAKQ 201934
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
334 PM EDT Sun Aug 20 2017

.SYNOPSIS...
High pressure becomes centered off the Mid Atlantic coast tonight
through Tuesday. A cold front crosses the area late Wednesday.

&&

.NEAR TERM /TONIGHT/...
High pressure slides offshore allowing winds to become more srly.
Pockets of moisture after midnight result in some fog development
across srn and ern shore areas. Lows in the upr 60s-lwr 70s.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Models track an area of low pressure north of the fa Mon. This
combined the a trailing trof should be enough of a trigger for
sct convection to develop across the mts then drift e-se across
the northern most zones of the fa after 18Z. Will carry low chc
pops mainly north of RIC for now. Otw, dry with highs upr 80s-lwr
90s except low-mid 80s at the beaches. Evening pops across the
lwr MD ern shore Monday night, otw dry with lows 70-75.

Hot/dry Tues ahead of the approaching cold front. 85-90 along the
coast, 90-94 west of the bay.

Dry most of Tues night except increasing moisture should lead to
a few shwrs by daybreak across nrn most zones. Lows low-mid 70s.

Frontal boundary a bit slower to traverse the fa Wed. This combined
with a weak wave progged to move east along it will spread widespread
moisture and support likely pops in the afternoon. Another round of
mdt to hvy downpours possible ahead and along the fropa. Highs 85-90.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A cold front gradually drops through the area Wednesday
night into Thursday morning. Modest ascent accompanies the front
within the RRQ of a ~110kt jet over New England along with pw values
around +1 st dev. The highest PoPs (high chc/likely) based on 27/12z
data are forecast across srn VA/NE NC. PoPs across SE portions
gradually diminish to 20-40% by Thursday aftn. Thunder will be
maintained into Wednesday evening, with showers thereafter as stable
NE flow prevails in the wake of the front. Drier air gradually
filters in from the NW late Wednesday night into Thursday with
partial clearing across the nrn tier counties. Lows Wednesday night
range from the mid 60s NW to the low 70s SE, followed by highs
Thursday in the upper 70s to low 80s. ~1025mb (+1 st dev) high
pressure builds from the Great Lakes across the Saint Lawrence
Valley and into New England Thursday nigh through Sunday. This will
result in persistent onshore flow, which combined with a drier
airmass will result in a series of pleasant days with highs in the
upper 70s at the coast to low 80s inland, with lows in the upper 50s
to low 60s inland, and mid/upper 60s along the coastlines.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
VFR conditions expected most of the forecast period with only
sct CU btwn 3-4K FT over the next svrl hrs. Concern once again
tonight is for patchy fog development as the winds become SSE.
Kept vsbys in the MVFR range for now between 06Z-12Z, but some
guidance suggests lcl IFR vsbys psbl across inland areas.

Any morning fog burns off around 12Z Monday with VFR conditions
to follow.

OUTLOOK...
The next cold front approaches the region Wed. Sub-VFR conditions
and showers/tstms will be possible Wed, and may linger across SE
terminals into Thu morning.

&&

.MARINE...
Latest surface analysis has a high pressure centered over the
region. The high pressure moves off the coast Monday through Monday
night and a cold front approaches the waters Tuesday night through
Wednesday. The front pushes out of the area by Thursday with high
pressure building back into the region for the remainder of the
forecast period. Obs indicate generally NE/E winds of 5 to 10 knots
over the waters with waves of 1 to 2 feet and seas of 2 feet. The
flow becomes SE around 10 knots on Monday as high pressure moves
offshore. Winds increase and become southerly ahead of the
approaching cold front Tuesday through Tuesday night. Winds speeds
may approach 15 to 20 knots over the bay and ocean with seas
building to 3 to 4 feet, potentially up to 5 feet north/20nm out,
and waves building to 2 to 3 feet. A Small Craft Advisory may be
needed for the Chesapeake Bay Tuesday night. Winds shift to the N/NE
behind the front on Wednesday through Thursday around 10 to 15 knots.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...AJZ
AVIATION...MPR
MARINE...AJB