Area Forecast Discussion
Issued by NWS Wakefield, VA

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575
FXUS61 KAKQ 250600
AFDAKQ

Area Forecast Discussion
National Weather Service WAKEFIELD VA
100 AM EST Sat Feb 25 2017

.SYNOPSIS...
A cold front tracks across the Ohio Valley tonight as low
pressure persists off the Southeast Coast. The front crosses
the local area Saturday afternoon and evening. High pressure
and more seasonal conditions return for Sunday and Monday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Mild temperatures late this evening, with many locales across
the forecast area still in the 60`s. A southerly wind of 5-10
mph has helped keep temperatures warm as high pressure slides
farther offshore. Less wind near the surface ridge axis across
the southeast local area in tandem with low level moisture
indicated in BUFKIT soundings and less cloud cover should be
able to support patchy, shallow fog late tonight into tomorrow
morning. Otherwise, increasing clouds from the west ahead of an
approaching cold front. Lows in the mid to upper 50`s.

Previous Discussion...
A potent sfc low entering Michigan late this aftn will continue
to intensify/deep overnight as it tracks NNE into Canada. The
associated sfc cold front is expected to cross the Ohio Valley
and become located over the wrn Appalachians by morning.
Conditions for the Mid Atlantic Region tonight will be warm and
calm with lows generally in the mid 50s (lower 50s Atlantic/Ches
Bay beaches north of the York River). Patchy ground fog may be
possible again closer to daybreak.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
Potent sfc low now in Canada (just NE of Lake Huron by daybreak)
will continue to track NNE to the east of Hudson Bay by Saturday
evening. As the strong mid-level shortwave feeds into this
system, models are trending twd a more longitudinal tilt to the
upper level features which would likely slow the arrival of the
cold front (into the local area) until mid aftn. The main
caveat working against this will be the strong, unidirectional
westerly flow throughout the atmospheric column and the much
colder air behind the front that could actually accelerate the
front through the region. With the best dynamics located farther
north, am leaning twd the slower timing. If fog develops around
daybreak, this could effectively prime the atmosphere to support
airmass thunderstorms ahead of the cold front in the aftn due to
more low-level moisture present than models are really showing.
In addition, breezy S-SW winds gusting to 25 mph and ample warm
air advection ahead of the front will warm daytime temps into
the mid 70s NW to upper 70s (maybe 80?) SE. We may flirt with a
few record highs. Please see Climate Section below for more
information. The aforementioned unidirectional wind shear will
also be a huge proponent in the development of strong, gusty
winds with any thunderstorms that develop as well as the
formation of line segment type convection. SPC has the area
within Marginal Risk for isolated severe storms. Since best
dynamics/instability remain across the nrn half of the CWA, will
maintain the thunderstorm wind threat in the HWO and add in the
rest of the VA counties.

Once the front exits the area Saturday evening, winds veer to
the NW and remain breezy overnight (especially at the immediate
coast) as much colder air rushes into the region. Temperatures
will be more seasonal with lows in the low-mid 30s NW to the
upper 30s/around 40F SE. Sfc high pressure builds across the
Southeast States Sunday, up along the SE VA coast Sunday night,
and then moving well off the Mid Atlantic Coast on Monday.
Conditions will be dry and more seasonal on Sunday with mostly
sunny skies and breezy west winds. Highs in the lower 50s
(mid-upper 40s Nrn Neck and MD/VA Eastern Shore). Winds decouple
Sunday night with light south winds but the area remains
somewhat wedged in the cooler airmass. Lows generally 31-35F
inland (upper 30s to around 40 immediate coast). Clouds increase
late Sunday night into Monday as the sfc high moves offshore
and shortwave moisture/energy begins streaming into the region
from the southwest. Forecast remains dry with temperatures
generally warming into the lower 60s (upper 50s far nrn counties
and MD/VA Eastern Shore).

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A couple of opportunities for much-needed-rain are showing up in
the medium range model guidance for next week. The first such
opportunity is Monday night into Tuesday as a disturbance lifts
NE across the region in the mid/upr levels. Will carry solid chc
pops (40-50%) during this time with models in decent agreement.
There is a brief reprieve Tuesday night before the next system
is expected to impact the region during Wednesday. Subtle timing
differences exist between the GFS and ECMWF with regards to
timing of the onset of pcpn. However, agreement is good enough
in the models at this point for solid chc pops (~40%). Drier
weather looks to return late next week with high pressure
attempting to rebound. Highs will remain unseasonably warm
Tues/Wed from the mid 60s to the mid/upr 70s (warmest Wed).
Trending cooler next Thursday/Friday with highs returning to the
mid 50s to low 60s and lows in the 30s.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
High pressure is centered off the coast as of 06z and is ridging
to the SW along the Southeast Coast. Mostly clear conditions
are prevailing with some cirrus, and a light S/SE wind around
5-8kt. Bkn cigs ~5kft are developing W of RIC. Surface high
pressure will continue to prevail through the morning.
Statistical guidance seems too aggressive with fog/stratus,
with the latest numerical guidance showing less fog. A period of
MVFR vsby has been included for SBY/PHF/ORF/ECG but confidence
for fog remains low. Showers/tstms are expected to develop
during the aftn with a strong line possible from 20-00z. High
pressure builds in from the W Saturday night into Sunday, with a
gusts NW wind possible tonight into early Sunday, and into
Sunday aftn for SBY. High pressure slides offshore Sunday night
into Monday, followed by weak low pressure Monday night into
Tuesday, which brings a chc of rain. Another cold front
approaches from the W by Wednesday.

&&

.MARINE...
High pressure will move further off the Mid-Atlantic coast
tonight as low pressure lifts NE well off the Carolina coast. A
cold front will push from the Ohio Valley tonight and ewd across
the mountains Saturday. A SSE wind will remain aob 15kt through
tonight, and may increase a few kt Saturday due to a tightening
pressure gradient, but should still remain sub-SCA, although
locally stronger gusts are possible with tstms Saturday
aftn/early evening. Seas are currently running 4-5 ft off the NC
OBX, and will increase to 4-5ft all ocean zones tonight into
Saturday as long period swell arrives from the low offshore.
Waves in the Bay will average 1-2ft. The cold front will cross
the coast Saturday eve/night followed by modest CAA and strong
pressure rises. NW winds will average 15-25kt with gusts to 30kt
and 4-6ft seas/3-4ft waves thru midday Sunday. SCA flags have
been hoisted this afternoon for the Bay, Sound and Rivers. SCA
flags will remain in effect for the coastal waters now thru
midday Sunday to account for both events. The wind diminishes
Sunday afternoon as high pressure builds into the region. High
pressure quickly pushes offshore Sunday night into Monday with
the wind becoming S.

&&

.CLIMATE...
Feb 2017 is shaping up to rank among the warmest on record
given continued warmth over the next week. Daily record highs
are listed below for today and Sat, with the top 3 warmest
February`s on record listed below that. Expecting RIC, ORF to be
the 2nd warmest and ECG to be at least into the top 3 warmest. SBY
looks on track to be 4th or 5th warmest.

Daily Record Highs for Saturday 2/25:

        2/25
     ----------
RIC  83 in 1930
ORF  81 in 1930
SBY  80 in 1930
ECG  77 in 1985

Warmest February`s on record (average temps):

* RIC: (most likely finish for 2017: 2nd warmest)
  1) 49.9 (1890)
  2) 48.5 (1976)
  3) 48.1 (1884)

* ORF: (most likely finish for 2017: 2nd warmest)
  1) 52.4 (1890)
  2) 50.5 (1909)
  3) 50.1 (1990)

* SBY: (most likely finish for 2017: 4th warmest)
  1) 46.1 (1976)
  2) 45.8 (1984)
  3) 45.7 (1925)

* ECG: (most likely finish for 2017: 3rd warmest)
  1) 52.1 (1990)
  2) 51.8 (1939)
  3) 50.3 (1976)

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 6 PM this evening to 4 AM EST Sunday
     for ANZ635>638.
     Small Craft Advisory from 6 PM this evening to 6 AM EST Sunday
     for ANZ630>634.
     Small Craft Advisory until noon EST Sunday for ANZ650-652-654-
     656-658.

&&

$$
SYNOPSIS...BMD/MAS
NEAR TERM...BMD/SAM
SHORT TERM...BMD/MAS
LONG TERM...JDM
AVIATION...AJZ
MARINE...JDM
CLIMATE...AKQ



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