Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 181930
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
230 PM EST Sat Nov 18 2017

.SYNOPSIS...
A strong cold front moves across the area late tonight then pushes
off the coast Sunday morning. High pressure builds into the area
Sunday afternoon through Tuesday. The next cold front crosses the
area early Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Latest MSAS has a warm front located ivof the Mason-Dixon line. The
main low lifts across the Gt Lakes and into southern Canada late
tonight with the trailing cold front not progged into the area until
after midnight. Latest data supports a dry evening across the fa
with pcpn not moving east of mts until around 04Z. Expect rising
dewpoint temps as the low level S-SW flow quickly increases PW`s
into the 1"-1.25" range. Thus, temps not falling much this evening
with readings between 55-60.

Latest data continues to support a quick-moving band of showers
along and ahead of the cold front just after midnight out in the
piedmont, reaching the coast by Sunday morning. The increasing PW,
along with a narrow axis of low-level convergence/forcing, will lead
to a broken line of showers through the overnight period. Thus have
maintained likely to categorical pops, highest across the north. No
CAPE to speak of, so kept thunder out of the grids.

Breezy to windy conditions continue through the night. H92-850 winds
increase to 40-50 kt as gradient tightens just ahead of the front.
Expect strongest winds to be within a few hours of frontal passage
as subsidence behind the departing boundary mixes down some of that
wind. Mild most of the night east cooling off late across the west.
Lows upr 40s west to mid-upr 50s along the coast.


&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Cold front and any lingering shwr activity along the coast arnd 12Z
quickly moves offshore by 15Z. Tsctns show rather quick drying of
the column so expect skies to become mstly sunny. Blustery with
gusty W-NW winds and only a slow rise in temps despite the sun.
Winds diminish towards sunset. Highs in the mid 50s-lwr 60s.

Sfc high settles over the sern states Sun night and Mon then drifts
off the coast Tues. Passage of an upr level system will usher in one
last surge of CAA Sun night. Otw, dry with a slow warming trend.
Lows Sun night in the upr 20s NW to mid 30s SE. Highs Mon in the upr
40s-lwr 50s. Lows Mon night in the 30s to near 40 se. Highs Tue in
the upr 50s to lwr 60s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Model differences make for a challenging mid week and holiday fcst.
The next cold front progged to cross the area Tues nite. Challenge
comes from just how much moisture gets entrained ahead of the front
from a trof off the Carolina coast and weak low progged to move ne
along it? GFS much more aggressive with the moisture than the ECMWF.
For now, elected to keep measurable rainfall east of I95 Tue nite
and Wed with slght chc pops across the east Thurs. Lows Tue nite in
the 40s to near 50 se. Highs Wed 55-60.  Lows Wed nite in the 30s to
lwr 40s se. Cool Thurs with highs mid 40s-lwr 50s.

Dry and cool Fri and Sat as high pressure builds into the area.
Highs Fri 50-55. Lows mid 30s-lwr 40s. Highs Sat 55-60.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
VFR conditions to start the forecast period with only high/mid
level clouds overspreading the region through 04Z. South winds
become gusty btwn 15-25 kts. Main concern this forecast will be
one of wind shear tonight with models showing 35-50kt at 2K ft
AGL. Added WS to all TAF sites ahead of the cold front tonight.

The cold front crosses the area btwn 08Z-13Z Sun with a band of
showers. TSCTNS show some short-lived MVFR ceilings with the
showers along and just ahead of the fropa. Winds quickly swing
around to the W-NW post-frontal and will be highest within a few
hours of frontal passage, but will remain gusty through Sunday.
West winds avg 15-25 kt with gusts 30-35 KTS.

Outlook: High pressure builds over the area later Sunday through
Monday then tracks off the sern coast Tuesday. VFR conditons
expected during this time frame.

&&

.MARINE...
High pressure slides off the Carolina coasts today as a strong
cold front approaches the area from the west today. Winds a tad
slower to increase through this morning. By this aftn, SW winds
will increase to 15-20kt as the pressure gradient tightens
significantly with the high offshore and the cold front passing
through the Ohio Valley. 00Z model guidance shows impressive
pressure falls of 6-9mb occurring this aftn into this evening
ahead of the front. Expect SW winds to increase to 20-30kt with
gusts ranging from 25-35kt. The pressure gradient tightens up
more after midnight tonight with gusts increasing to 40kt all
coastal waters...mainly due to a strong temperature gradient
associated with this low pressure system. In addition, gusts
could reach up to 35kt over Currituck Sound between 200 AM to
900 AM. Will need to monitor gale gust potential here and
possibly the mouth of Ches Bay. Seas build to 3-5ft north/3-4ft
south this aftn...then build to 5-8ft north/5-6ft south after
midnight tonight. Waves build to 3-4ft this aftn...then build to
4-5ft late this evening.

Cold front crosses the waters around sunrise Sunday morning.
Strong cold air advection, a very persistent tight pressure
gradient, and rapid pressure rises (5-9mb) behind the front will
all contribute to a continuation of strong NW winds 20-30kt with
gusts of 25-40kt through Sunday. Windy conditions will be common
everywhere on Sunday (including over land areas) and generally
uniform with slightly stronger winds occurring over the warmer
waters. Winds should remain generally unchanged Sunday night
with NW winds averaging 15-25kt with gusts averaging 30kt. A
secondary surge in NW winds may be possible Sunday night as
coldest part of airmass swings across the area. However,
relaxing pressure gradient with high pressure building over the
Southeast States may prevent a surge from happening. High
pressure continues to build over the Southeast States into the
srn Mid Atlantic Region Mon/Mon night... sliding offshore on
Tuesday. Adverse boating conditions to subside during Monday
with more benign/quiet sub-SCA conditions anticipated through
Wednesday.

Gale warnings now in effect for all coastal waters from this
evening through early Monday morning. SCA flags begin on Ches
Bay by mid morning today through mid morning Monday morning.
River/Sound begin this aftn and persist through roughly sunrise
Monday morning. For specific details, please visit
www.weather.gov/wakefield/marinebrief.

&&

.EQUIPMENT...
KDOX remains down until further notice due to a pedestal fault.
Updates will be provided as they become available.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 7 AM EST Monday for ANZ633-635>638.
     Small Craft Advisory until 10 AM EST Monday for ANZ630>632-634.
     Small Craft Advisory until 7 PM EST this evening for ANZ650-
     652-654-656-658.
     Gale Warning from 7 PM this evening to 4 AM EST Monday for
     ANZ650-652-654.
     Gale Warning from 7 PM this evening to 3 PM EST Sunday for
     ANZ656-658.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR/MAM
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...MPR
MARINE...BMD



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