Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 240938
Area Forecast Discussion
National Weather Service Wakefield VA
538 AM EDT Mon Oct 24 2016
Low pressure pushes off the southern New england coast early this
morning, pushing a dry cold front through the local area late this
morning and afternoon. Cool Canadian high pressure builds in from
the northwest tonight through midweek. Low pressure will track
northeast through Great Lakes Thursday and Thursday night.
.NEAR TERM /THROUGH TONIGHT/...
The current surface analysis shows ~1025 mb high pressure
centered along the Gulf coast. To the north, ~982mb low pressure
was noted over eastern Canada...with a second area of ~1007 mb
sfc low pressure pushing E to near Long Island. The associated
sfc cold front extended WSW of this system back into the OH
Valley, with a sfc trough also in place to the lee of the
Appalachians. SW flow keeping a mixed atmosphere over the region
and the result is temperatures nearly 20 degrees warmer this
morning than yesterday at this time (most areas avg in the mid 50s
to around 60 F).
The trough and associated low pull offshore later this morning with
the trailing cold front pushing through the area during the aftn.
The frontal passage will be dry and produce deep mixing, and caa
will be delayed until tonight with downslope flow. This will
allow for slightly warmer temperatures today with highs ranging
from from the low to mid 70s under a mostly sunny sky, with some
sct aftn cu (mainly e of i-95). There should be enough mixing
tonight with caa to keep lows generally in the low/mid 40s (upper
40s se). However, the piedmont could decouple late, which will
allow lows to fall into the upper 30s to around 40 F. Not
expecting much more than patchy frost over the piedmont.
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Sunny and much cooler on Tuesday as models remain in good
agreement with strong/ 1032mb+ high pressure centered over the
Great Lakes and ridging SE into the Carolinas. N/NW low level
wind flow and NAM/GFS 850mb temperatures plummeting to -1 C over
the MD eastern shore would only support high in the mid- upper 50s
there, with highs near 60 F/lower 60s across interior VA/NC (850mb
temps of +3 to +5C).
The high continues to build in from the NNW Tuesday night. This
appears to be the coldest night through midweek (and probably of
the season so far, with lows ranging from the mid/upper 30s over
much of the CWA (with the potential for a light freeze in a few of
the coldest spots in the Piedmont), with low/mid 40s near the
immediate coast. This will bring the potential for frost except
along the coast. One thing that could keep temperatures a little
warmer is that the models continue to show modest mid-level
700-850 mb WAA, which could result in some clouds (mainly W).
If this were to occur, the potential for frost would be lower. Continued
cool Wednesday under a partly to mostly sunny sky with highs in
the upper 50s N, to low 60s S. There is the potential for highs to
hold in the 50s CWA-wide if more clouds do develop.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A series of northern stream disturbances will impact the region
through the extended period. The first developing upper trough will
drop over the Great Lakes Wednesday night and Thursday, pushing a
cold front into the Mid Atlantic region Thursday afternoon. Moisture
return will be limited in west to southwest flow aloft, with
precipitable waters progged around one inch. Best dynamics also
expected to pass north of the region, but sufficient height falls
and winds aloft will provide forcing for ascent along the cold front
for chance to solid chance POPs south to north across the forecast
area on Thursday...with lingering chc pops Thursday night. Highs
Thursday range from the low 60`s northwest to upper 60`s southeast
under a partly cloudy to mostly cloudy sky. High pressure builds
into the region Friday for dry wx all areas. Highs generally in the
mid to upper 60`s. Confidence decreases thereafter as medium range
guidance struggles to handle the evolution of the next northern
stream disturbance. GFS is generally more progressive with the late
week system, pushing it quickly offshore Friday night/Saturday.
ECMWF suggests cyclonic flow will linger over the Northeast into
Saturday. The main difference becomes the next trough that will
impact the region late in the weekend into early next week. The
associated cold front will impact the region late weekend into early
next week. For now, will introduce chances for precip
Saturday/Saturday night across the north to northeast forecast area.
Saturday looks to be the warmest day with highs in the upper 60`s to
around 70. Highs Sunday generally in the mid to upper 60`s. Mild
overnights are forecast Thursday night through Saturday night, with
lows generally in the mid/upper 40`s to low 50`s.
.AVIATION /10Z MONDAY THROUGH FRIDAY/...
Dry weather with no flight restrictions to prevail during the 06Z
TAF period. Have continued with low level wind shear for the RIC
TAF given around a 40-45 KT low level Jet through 10-11Z.
Elsewhere, SW winds to avg 10-15 KT through 12Z, shifting to the
WNW by late morning/noon as a cold front passes through the area.
Some scattered cumulus possible this aftn but if any CIGS do
briefly occur they would be at or above 4000 ft.
OUTLOOK...Dry and VFR conditions can be expected through
Wednesday. Fog and/or low clouds will be possible Thursday
morning as high pressure moves off the coast and moisture
increases over the area. Another cold front crosses the area
Thursday night bringing a chance of showers. Dry weather returns
SCA conditions will continue for much of the marine area this
morning with SW-W winds of 15-25kt. Pressure gradient relaxes
briefly late this morning into mid-afternoon as a cold front
approaches and then crosses the waters. Expect another northwest
surge late this afternoon through tonight with a NW-N wind of 15 to
25 knots. Winds expected to remain below SCA levels on the rivers
with the second surge but may briefly reach 15-20 kt on the
Currituck Sound. Due to low confidence will not extend SCA for the
Sound past Noon at this time. Seas 3-5 feet (up to 6 ft southern
outer waters tonight). Waves 2-4 feet. Seas will linger AOA 5 ft
across the southern waters thru Tuesday morning so have extended SCA
for the southern waters until 1 pm Tuesday. High pressure builds in
from the northwest Tuesday, with sub-SCA conditions expected through
mid week. The next cold front pushes across the waters on Thursday.
-- Changed Discussion --Modest west to southwest winds have resulted in negative tidal
departures in the middle to lower Chesapeake Bay and the Atlantic
coastline. Water levels will come close to low water thresholds
during the low tide cycle this morning. However, low water
advisories are not anticipated.
-- End Changed Discussion --
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ630>632-634-
Small Craft Advisory until noon EDT today for ANZ633-638.
Small Craft Advisory until 1 PM EDT Tuesday for ANZ656-658.