Area Forecast Discussion
Issued by NWS Wakefield, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 250127
Area Forecast Discussion
National Weather Service Wakefield VA
927 PM EDT Mon Apr 24 2017
Low pressure off the Carolina coast tonight, will slowly track
across the North Carolina coastal plain Tuesday, then continue
northeast along the Mid Atlantic coast Tuesday night and Wednesday.
High pressure builds into the area for the rest of the week.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Latest MSAS shows low pressure just offshore from CHS with a coastal
front extending NE to near HAT. Deep moisture flow around this cut
off low continues to push waves of rain NNW into the wedged cool air.
Latest high res model trends are for this to continue into this eve
with the pcpn becoming more spotty light rain/drizzle after ss thru
through 06Z. Airmass begins to recover from the wedge especially
east of I95 where pcpn becomes more showery than stratiformed. Data
also suggests a bit of (elevated) instability well north of the
coastal front. Thus, will continue the high likely to cat pops all
areas and keep thunder chcs east of I95 after midnight. Expect a
general rain over the piedmont where wedge remains locked in place.
Additional moisture arrives from the se late. Nearly steady temps
with lows from the lwr 50s NW to the lwr 60s SE.
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Models differ on exact track / intensity of the tropical moisture
progged to get absorbed then rotate around the low Tues. NAM /
ARW`s track seems a bit out of place (to far north) given the
synoptic setup, thus leaned toward a GFS / SREF blend of taking
the moistures center inland over the NC coastal Plain (merging
both systems into one) by 18Z with the entire system then slowly
lifting ne to a position near VA Beach Wed eve, then tracking
ne from the Delmarva coast to just east of OXB by 12Z Wed.
Cat pops all areas Tuesday with periods of mdt to lclly hvy rainfall
shifting ne towards the ern shore by 21Z. Low thunder chcs ern half
of fa with even some brightening or partial sun across the se as a
dry slot may tend to cut off the deep moisture feed. Highs lwr 60s
NW to low-mid 70s SE.
Likey to cat pops cont Tue evening as the system slowly moves up the
eastern shore. Pops taper off west to east after 06Z as the best
moisture gets shunted towards the coast. Lows 55-60.
Low pressure progged to move slowly away from the Delmarva coast Wed
morning then gets pushed farther offshore after 18Z as high pressure
builds into the area from the west. Kept low chc pops along coastal
areas during the morning (wrap around moisture), otw decreasing
cloudiness west to east. Milder with highs in the 70s, except mid-
upr 60s along the eastern shore.
Mainly clr and mild Wed nite. Lows upr 50s-mid 60s. Upr level ridge
builds across the area in the wake of the departing low Thurs. Dry
with summer-like temps expected. Highs in the mid-upr 80s west of
the Bay, upr70s-lwr 80s along the coast.
Headline wise, decided to not issue any flood headlines attm. QPF as
of this writing has been around 2 inches on a line from AVC-RZZ, less
than one inch elsewhere. Seems models have overdone QPF up to this
point and have now shifted the heaviest QPF a bit farther to the west.
Quick check with the countys reveal no water issues. Although another
1 to 2 inches of rain are possible there, 3-6 HR FFG levels are not
expected to be reached. Could have some minor issues given lclly
hvy rates Tues morning, best handled with short fused statements.
Some 2+ inch amounts are also possible along the nrn Outer Banks
in convection closer to the front.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Long term period will feature above normal temps with mainly dry wx.
For Thu night/Fri, deep SWly flow continues across the eastern
seaboard as an upper-level ridge then builds in through the weekend
allowing for warm temps and dry wx as most of the energy aloft will
stay N and W of the local area. At most a 20% chance of a late day
shra/tstm Fri and Sat. High temps Fri through Sun in the 80s,
pushing near 90 Sat and Sun. Low temps in the mid/upr 60s.
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --Complex low pressure system over the Carolinas and off the
Carolina coasts will merge overnight and move through NE NC and
SE Virginia. IFR/LIFR conditions expected to prevail through
the overnight with periods of rain and IFR/MVFR conditions
through the day on Tuesday as the low continues to lift north.
Periods of light to moderate rain will continue into Tuesday
aftn/evening. Northeast winds will overnight as the low
approaches the area. Very windy conditions will be possible
along the coast tomorrow morning with gusts potentially in
excess of 30 knots.
Outlook: The low will be slow to move up the coast on Tuesday
with rain, wind, and IFR/MVFR conditions continuing into the
early to late evening. Conditions will begin to slowly improve
overnight Tuesday into Wednesday as the system moves farther
north. Dry weather is in store for Thursday and Friday as high
pressure builds over the southeast states.
-- End Changed Discussion --
Deteriorating marine conditions for tonight as E/NE flow strengthens
in response to sfc low pres developing near the SE coast in
association with a mid-level cutoff low. Mainly 15-25 kt winds this
eveng...increasing to 20-30 kt over the Bay and coastal wtrs after
midnight. Seas build to 5-8 ft tonight. The sfc low slides up the NC
coast through Tue, with gale warnings in effect for 35-40 kt gusts
for the entire marine area except the Upr James/York/Rappahannock
Rivers where gusts up to 30 kt are expected. Think much of the wind
may stay aloft due to strong WAA, but with decent pres falls over
the area, upgraded the northern Bay and Sound to gale warnings also.
Seas up to 8-11 ft, with a high surf advisory remaining in effect
for 8-9 ft waves in the surf zone. Marine conditions then steadily
improve Wed into Thu as the sfc low pulls off to the NE, and a weak
pres gradient is expected on the back side of the low.
Current tidal departures are averaging around 1 to 1.5 feet in
the lower Bay and southern coastal waters due to ongoing onshore
flow. Have issued another round of coastal flood statements for
the high tide cycle tonight. Levels are expected to stay below
minor flooding thresholds. Increasing easterly flow ahead of
low pressure lifting over the Carolinas tonight will push tidal
departures toward 2 feet Tuesday morning. Depending on the
exact track of the low, high end minor to low end moderate
coastal flooding is possible Tuesday night. Departures subside
Wednesday as low pressure lifts along the Northeast coast and
flow becomes offshore.
MD...High Surf Advisory from 6 AM to 6 PM EDT Tuesday for MDZ025.
Wind Advisory from 7 AM to 1 PM EDT Tuesday for MDZ025.
NC...Wind Advisory from 2 AM to 8 AM EDT Tuesday for NCZ017-102.
High Surf Advisory from 4 AM to 11 AM EDT Tuesday for NCZ102.
VA...High Surf Advisory from 6 AM to 6 PM EDT Tuesday for VAZ099-
Wind Advisory from 7 AM to 1 PM EDT Tuesday for VAZ099-100.
Wind Advisory from 2 AM to 8 AM EDT Tuesday for VAZ098.
High Surf Advisory from 4 AM to 11 AM EDT Tuesday for VAZ098.
MARINE...Small Craft Advisory until 4 PM EDT Tuesday for ANZ635>637.
Gale Warning until 1 PM EDT Tuesday for ANZ630>632-634-654-656-
Gale Warning until 10 AM EDT Tuesday for ANZ633-638.
Gale Warning until 4 PM EDT Tuesday for ANZ650-652.