Area Forecast Discussion
Issued by NWS Wakefield, VA
FXUS61 KAKQ 202023
Area Forecast Discussion
National Weather Service Wakefield VA
323 PM EST Fri Jan 20 2017
A frontal boundary will weaken as it stalls across the Mid Atlantic
region tonight. Low pressure over the nations mid section Saturday
and Sunday will intensify as it slowly tracks east across the Mid
Atlantic region Sunday night and Monday. The intense low will move
off the New England coast Tuesday.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Latest MSAS has high pressure off the New England coast with a warm
front still west of the mts. 12Z data now showing this boundary
weakening/washing out across the region tonight leaving the fa in a
saturated airmass as weak high pressure builds aloft. Tsctns showing
abundant low level moisture but little if any support for measurable
pcpn after 00Z. Thus, expect any light rain to end early with patchy
fog/drizzle developing across the area. Bufkit showing a combo of
stratus and fog so have trended the grids towards that solution.
Lows upr 30s-lwr 40s.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Not much change in synoptic features seen on Saturday as the fa
remains in between systems with weak high pressure overhead. Thus,
expect patchy fog/drizzle to continue into the morning hours with a
slow improvement (albeit remaining mstly cldy to cldy into the mid
day and afternoon hours). Moisture begins to increase from the
s/sw late. Will carry low chc shwrs across swrn most zones after
21Z. Mild despite no sun. H85 temps support highs from the mid-
upr 50s Delmarva to upr 50s-lwr 60s west of the Ches Bay.
Challenging forecast thereafter as model differences appear Saturday
night and continue through Monday. Given how dry the 12Z GFS is
compared to the previous run (basically dry through 12Z Sun), have
trended this forecast more in line toward a NAM/ECMWF blend where
shortwave energy moves NE Saturday night resulting in chc to likely
pops overspreading the fa. Data shows little instability but a decent
amount of Atlantic moisture getting entrained from the SE. Thus, could
see some mdt rainfall rates at times across the south. The high to
the north keeps nern zones with chc pops. Lows from the mid 40s
Delmarva to lwr 50s srn most zones.
Next shortwave tracks across the fa Sunday with categorical pops as
a good amount of lift and low level moisture is noted. Increasing
PW`s will result in mdt to locally heavy rainfall. Warm frontal
boundary progged to drift north to near the NC - VA border so
will keep slght chc thunder across southern half of fa during
the afternoon. Warm with highs in the upr 50s to lwr 60s north
to mid-upr 60s south.
Models continue to have trouble with the stacked upr level low
progged to slowly cross the region late Sunday night and Monday.
Categorical pops for shwrs Sunday night. Lows upr 40s - mid 50s.
At some point in time, a triple point low is forecasted to cross
Virginia. Current timing is Monday which will continue to produce
widespread shwrs across the north with a dry slot potentially
cutting off pcpn across parts of the area Monday afternoon.
However, enough instab noted to keep thunder mentioned across
the SE in the warm sector. Highs mid 50s to lwr 60s.
Qpf through Monday should average one to two inches with locally
higher amounts possible.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Upper low pressure lifts northeastward away from the region Monday
night and Tuesday, with precipitation chances winding down by
Tuesday morning. High pressure is expected to return Tuesday night
into Wednesday. A cold front associated with an upper low lifting
over eastern Canada is progged to push across the region late
Wednesday night and Thursday. Will hold onto slight chc to low chc
pops (20-30%) during this time. High pressure returns again next
Friday with temperatures falling back below normal for this first
time in awhile. Highs Tuesday mostly in the 50s. Highs Wednesday
from the mid 50s Eastern Shore to the low 60s inland. Thursday`s
highs back in the 50s, then cooling into the 40s next Friday.
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Rain moving across the fa this afternoon ahead of an approaching
warm front. Initially, the pcpn is falling out of a fairly high
cloud deck (6-8K FT), but obs to the west showing IFR stratus
overspreading the western piedmont as the second wave of pcpn
tracks across the region. Thus. a TEMPO group was added over
the next 2-4 HRS given the changable conditions. Latest data
continues to show abundant low level moisture tonight along with
areas of fog/drizzle. This will likely result in widespread IFR
(with local LIFR) conditions from this evening right on though
abt 15Z Sat. Expect a slow improvement toward the end of the
OUTLOOK...Ceilings and visbilities will deteriorate again
Saturday night and Sunday morning with IFR possible at each of
the TAF sites. Periods of widespread rain are expected Sunday
through Monday as a strong low pressure system moves from the
southern Great Plains and across Virginia Monday to off the New
jersey coast Tuesday. This will result in unfavorable conditions
for aviators. The weather improves by Tuesday.
Winds remain E aob 10kt this afternoon into this evening before
becoming NE and N tonight. Long period swell will keep seas between
3-4 ft into this evening. Winds become E then SE Saturday with
speeds remaining 10kt or less. Seas 2-3ft; waves 1-2ft.
Winds become SE 10-15 kt on Sunday as the first of two low pressure
systems impact the region. Seas build to 3-4 ft, except up to 5 ft
southern outer waters. The second low pressure system begins to
impact the region Sunday night with winds remaining 10-15 kt, except
increasing to 20-25 kt north of Chincoteague early Monday morning. A
brief period of gale gusts is possible early Monday morning across
the northern coastal waters. However, models continue to push the
highest wind threat further north into DE/NJ. Seas 3-5 ft across the
south Sunday night, building to 5-8 ft off Ocean City by early
Monday morning. Low pressure lifts north through the interior Mid-
Atlantic during Monday before lifting north of the area on Tuesday.
Winds will vary from SE to SW 10-15 across much of the marine area
Monday, while generally remaining E across the northern coastal
waters and diminishing through the day from 20-25 kt down to 15 kt.
Seas build to 6-10 ft north while remaining 3-5 ft south. Winds
become NW all waters on Tuesday with SCA conditions probable,
especially for the coastal waters. Seas 4-8 ft.
KDOX remains offline until further notice. Replacement parts are