Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 230125
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
925 PM EDT Mon May 22 2017

.SYNOPSIS...
Low pressure will track off the Mid Atlantic coast overnight, as
a frontal boundary drops south of the area. The front will lift
back north into the region on Tuesday, as a potent low pressure
system tracks across the local area. Unsettled conditions
continue Wednesday and Thursday as an upper level trough
approaches from the west.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...

Latest wx analysis reveals sfc low pressure pushing offshore of
the VA/NC coast this evening. Cooler, more stable air behind
convective line of showers and storms from earlier this evening
has left a temporary lull in rain across the area. Lone
exception for the local area is with a few showers NW of RIC
metro area which will continue through the early overnight
hours. Have accounted for these with a low 20-30 pop for
isolated-widely sct showers through 06z or so. Otherwise, look
for little more than some patchy drizzle through much of the
night...with some partial clearing across the Northern Neck and
the Lower Eastern Shore to lead to some patchy fog through late
tonight.

Rain chcs return (srn VA/interior NE NC) after 08z/4 am EDT. An
upper disturbance currently noted on early evening WV imagery
sliding across the Mid-South will pivot NE ahead of the cool
front toward the Carolinas late tonight, reaching the lower
Mid-Atlantic by early Tuesday morning. Likely to categorical
PoPs arrive for the SW corner of the area during this period
beginning by daybreak Tuesday. RAP/HRRR both implying some
impressive overrunning moisture with the arrival of this wave as
early as 6-8 am, and have accounted for locally heavy rainfall
potential across the southern third of the area for the early
portion of the AM rush. Lows range from the upper 50s far NW
zones...with lows in the low to mid 60s for most, under a partly
to mostly cloudy sky.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
The flow aloft remains SW Tuesday, with aforementioned shortwave
lifting newd across the Carolinas toward southern VA during the
morning, reaching the Mid-Atlantic/Delmarva coastal plain
during the aftn and evening. With deep layer moisture
returning, categorical PoPs quickly ramp up from SW to NE and
overspread the entire area for Tuesday. 22/12z suite of models
(NAM/GFS/GEFS/ECMWF/CMC) continue to show some differences in
timing and location and strength of this wave of low pressure,
but the general theme is for a potent system with deep anomalous
moisture transport per strong H925-H700 southerly flow and pw
values climbing to ~1.75" collocated with the favorable RRQ of a
potent 120-130kt jet over the Northeast Conus. The threat for
heavy rain and possible flooding will continue to be mentioned
in the HWO, and have opted against a flood watch at this time as
6hr FFG is generally 4-6" across much of the area, with some
values of 3-4" across the Piedmont and MD Ern Shore. QPF through
00z Wednesday averages 1-3" across the region, and higher
amounts are possible. Storm total QPF through Thursday ranges
from 1.5-3.5" (tonight through Thursday) The axis of heaviest
rain per 12z model consensus is generally in the I-85/US 360
corridor. The current high temperature forecast shows generally
low/mid 70s SE to the upper 60s/around 70 F central and mid 60s
far NW.

This shortwave/surface low push offshore Tuesday evening.
However, 22/12z NAM/ECMWF depict a secondary wave lifting across
the srn half of the are 00-06z Wednesday, so have bumped PoPs
up to 40-70% S to account for this. Yet another wave approaches
from the SW Wednesday aftn as an upper low approaches from the
W. This wave tracks across the region Wednesday evening through
the early overnight hours bringing another round of likely PoPs
along with a chc of embedded thunderstorms. Current 12z guidance
suggests the best instability remains offshore. However, the
potential for some strong to severe storms will need to be
monitored with 500mb height falls and strengthening/veering flow
at the 500mb level. Unsettled conditions continue into Thursday
with chc to likely PoPs continuing along with a chc of thunder.
Mostly cloudy to overcast Tuesday night through Thursday with
lows Tuesday night/Wednesday night in the upper 50s to mid 60s,
followed by highs Wednesday/Thursday ranging through the 70s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Trough axis tracks across the region Thursday night as the
surface low tracks just north of the region. Will keep mention
of chance POPs across the northeast portion of the local area
Thursday night. Dry conditions and a clearing sky is forecast
Friday as the trough axis and deepest moisture push offshore and
westerly flow aloft commences. Temperatures Friday generally
around average in the mid to upper 70`s. Upper level flow
becomes northwest Friday night and Saturday ahead of an upper
level ridge building over the Ohio Valley. A warm front lifts
into the region Saturday, providing a focus for showers and
thunderstorms, but overall moisture is expected to be limited.
Will keep only slight chance POPs for the Piedmont Saturday at
this time. Warmer, with highs in the upper 70`s to low 80`s.
Better chances for showers and thunderstorms are expected
Saturday night as upstream convection develops and tracks along
the frontal boundary and into the region. However, spatial and
timing differences exist so have capped POPs in the low end
chance range. Thereafter, unsettled conditions persist Sunday
through Monday as an upper level trough tracks across the
Midwest into the eastern CONUS. A great deal of uncertainty
exists in the medium range guidance, but it appears moisture
return will be limited. Will keep mention of low end chance POPs
in the forecast. Highs both days generally in the low to mid
80`s.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Low pressure and associated precipitation have moved off the coast.
Much of the stratus has cleared but some remains including southeast
Virginia where ORF continued with an IFR ceiling. A cold front just
southeast of the TAF sites will settle a little farther to the south
before returning to the north on Tuesday. Low pressure develops
along the front and moves northeast across southeast Virginia. The
exact track of the low will impact both wind directions and areas of
IFR. The lower ceilings will generally occur to the northwest of the
track.

IFR ceilings are expected to return overnight and especially toward
sunrise. Widespread precipitation develops Tuesday morning and
continues most of the day. The rain will be heavy at times...
reducing visibility. IFR ceilings will be widespread...
especially northern and western portions of the area.

OUTLOOK...Other low pressure systems will impact the area but not to
the extent as the one on Tuesday. Nevertheless...aviation
conditions will be reduced at times through Thursday. High
pressure builds over the area Thursday night and Friday with
drying. Moisture returns with a chance for precipitation
developing during the weekend.

&&

.MARINE...
Latest surface analysis centers a compact area of low pressure
over southeast Virginia/northeast North Carolina with a cold
front over the Piedmont. Winds were generally from the east to
southeast at or below 15 knots, with a few gusts to around 20-25
knots in convection. Seas average 2-4 feet and waves 1-2 feet.
The compact area of low pressure slides offshore this evening,
slowly drifting to the northeast. The cold front stalls along
the coast. Winds north of the boundary become northerly, and
remain west to southwest south of the front with speeds
generally at or below 10 knots tonight. Low pressure lifts
northeast of the area Tuesday as another area of low pressure
develops along the stalled frontal boundary. That area of low
pressure lifts across southeast Virginia Tuesday afternoon.
Could see an uptick in east to southeast winds Tuesday afternoon
ahead of the surface low, but pressure falls are not
particularly impressive. Have kept speeds around 15 knots
Tuesday afternoon. Have held off on SCA headlines at this time
due to low confidence based on differences in guidance and
marginal conditions. The low slides offshore Tuesday as the
front pushes offshore. Flow becomes north to northwest, but a
lack of cold advection results in sub-SCA conditions. Seas could
build to 4-5 feet out 20 nm in the northern coastal waters
Tuesday night. Again, low confidence so no SCA headlines at this
time. Flow becomes onshore Wednesday as another area of low
pressure tracks into the Ohio Valley. Seas generally 2-4 feet
with speeds of 10-15 knots.

The next front pushes offshore Thursday night, with increasing
southwest winds Thursday ahead of the front. SCA conditions are
possible.

&&

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

&&

$$
SYNOPSIS...AJZ
NEAR TERM...AJZ/MAM
SHORT TERM...AJZ/LKB
LONG TERM...SAM
AVIATION...LSA
MARINE...SAM



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