Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kakq 150809 
afdakq

Area forecast discussion
National Weather Service Wakefield Virginia
309 am EST Thu Nov 15 2018

Synopsis...
a complex area of low pressure over the southeast affects the
region Thursday. High pressure and dry conditions return Friday
into the weekend.

&&

Near term /through today/...
as of 930 PM EST Wednesday...

Hi pres was located invof New England this evening while complex
lo pres (one area invof Tennessee/Ohio valleys...the other near coastal
sc) will beginning to spread pcpn NE toward the mid-Atlantic
region. Cold/relatively dry air remains locked over the local
area as ceilings gradually lower and the pcpn is beginning to
spread in. All sfc based wet bulbs remain above freezing
attm...however W/ dew points mostly in the 20s...as -ra
begins...temps/wet bulbs expected to fall a bit. Given light
intensity to the initial few hours of pcpn...have expanded -ip
mention east into more of central/scentral Virginia overnight - though
won't discount very short period W/ -ip just about anywhere when
pcpn starts. Will leave the winter wx advisory for the areas
from Prince Edward- western Louisa as those areas will have the
highest potential for -zr/light glaze (esp on elevated surfaces.

At this time, wintry precip is not expected in the
immediate ric Metro...except for perhaps a very brief period of
sleet at the onset. Still...it will be a cold rain in the Metro,
with temps only expected in the mid-upr 30s Thu morning.

Otherwise, across the remainder of the area expect moderate to
locally heavy rain to fall late tonight through tomorrow with many
areas seeing 1-2 inches. The heaviest rain will fall across the far
east near the best frontogenetic forcing and low pres track. Latest
eps and gefs guidance suggests that the probability is quite low for
>2 inches of rain, however with the already saturated ground, it
will not take much for minor flooding and will continue the Flood
Watch for the entire area. Thunderstorms cannot be completely ruled
out across far NE NC with that area being near the low track, but
for now will leave out given the relatively poor lapse rates and
being a very small chance. Latest guidance suggests that the rain
will start to move out late Thu aftn as a dry slot moves in from the
SW.

Lastly, it will become quite windy especially at the coast with
strong east-NE winds developing in the pres gradient between the
low to the south and the strong high over the NE states. Will
issue a Wind Advisory for much of the area close to the coast
for Thursday.

Lows tonight will range from around 32 degs f northwest to the l40s
southeast. Highs Thursday will range from the mid-upr 30s far northwest to
temps in the mid-upr 60s across the far southeast.

&&

Short term /tonight through Saturday/...
as of 315 PM EST Wednesday...

After the low moves out Thu night, expect high pressure to build in
for Friday and into Saturday with mostly sunny skies. Temps will
still be cooler than average with the mean trough and lower than
average heights over the East Coast. Temps will rise into the
50s during the day and drop to 30s at night.

&&

Long term /Saturday night through Wednesday/...
as of 315 PM EST Wednesday...

Much quieter weather expected during the extended period. Sfc high
pressure centered over the area early Sunday morning weakens during
the day on sun, with dry/seasonable weather expected throughout the
area. A weak upper-level shortwave approaches the area on late
Sunday-Monday (coupled with a sfc cold front). Not much in the way
of rain expected with the fropa, but have pops of 15-30% for eastern
portions of the area late Sun night-Mon (best rain chances will be
in coastal NE nc). Northwest flow aloft will prevail from Mon PM through at
least midweek, with mainly dry weather and temperatures a few
degrees below seasonal averages. Another weak upper level shortwave
may swing through the mid-Atlantic on Wed. The GFS is showing a few
showers moving across the area, but the European model (ecmwf)/CMC keep US dry.
Decided not to add any mention of rain to the forecast attm.

Forecast highs Sunday range from the low-mid 50s northwest to around 60 in
in southeast Virginia/NE NC. The cooler air lags behind the front a bit, so highs
on Mon will still be in the 50s to near 60. Cooler on Tue/Wed, with
highs in the upper 40s to near 50 north/mid 50s south. Lows Sunday
night in the mid-upper 30s inland/low-mid 40s near the coast. Cooler
on both Monday and Tuesday night with lows ranging from ~30 northwest to
~40 in coastal southeast Virginia/NE NC.

&&

Aviation /06z Thursday through Monday/...
as of 310 am EST Wednesday...

1038mb high pressure is located over New England as of 08z, with
low pressure deepening off the Georgia coast, and another area of low
pressure centered over ern Tennessee. Light rain is spreading across
the area, with a mix ice pellets possible west of ric. Cigs are VFR
with vsby greater than 6sm. The low pressure system off the Georgia
coast is expected to track up the East Coast today, as the low
to the west weakens. Periods of moderate to heavy rain are expected
to overspread the region around and after 12z. MVFR/IFR vsby is
expected in rain today, with cigs falling to IFR later this
morning (earliest at ric). A line of heavy rain with a slight
chc of tstms is expected to affect ecg around the 19-22z
timeframe today. Elsewhere, expect rain to end from SW-NE late
this aftn through this evening. A NE wind will increase to
10-15kt inland to 15-25kt along the coast, with gusts as high as
35kt along the coast, and ~20kt inland. Cigs are expected to
remain IFR this evening after the rain ends. Drier air arrives
from the west later tonight with the wind becoming northwest and
conditions are expected to improve rapidly after 06z.

High pressure prevails Friday through Monday with VFR conditions
expected.

&&

Marine...
as of 415 PM EST Wednesday...

High pressure centered north of the region has temporarily allowed
the pressure gradient to slacken enough for winds to now avg
10-15 kt except for 15-20 kt over southern waters. Conditions
will rapidly deteriorate later tonight from S to north however as
secondary area of low pressure intensifies along the Carolina
coast and lifts north-northeast with strong sfc high over New England.

Replaced The Ramp-up Small Craft Advisory headlines with gale warnings (and
upgraded to gales for the York/Rappahannock river). The only
zone remaining in Small Craft Advisory is the upper James. With pressure falls of
~15 mb in 6 hrs progged from 15 to 21z Thu, winds are expected
to reach gale force by early Thursday morning over the south and
by mid/late morning farther North. East/NE winds will likely gust
to 35-40 kt in the Bay and southern coastal waters, and a little
higher to 40-45 kt on the ocean north of Cape Charles. Seas will
increase to 8-12 feet south and to 10-15 ft by late Thu
aftn/evening off the Eastern Shore. Bay waves will avg 4 to 6
feet with higher waves at the mouth of the Bay.

A brief lull in the winds is expected late Thursday night as
the low moves off the mid-Atlc coast. Winds turn to the west/northwest
Thursday night into Friday morning and potentially gust to gale
force once again over the coastal waters. Have extended the
gales north of Cape Charles through 10 am Fri morning for now
(elsewhere it looks more marginal so did not extend the gales
beyond thu). Winds will remain in the 20 to 30 knot range into
Friday afternoon. Winds and seas will remain stirred up into
early Saturday morning, likely requiring additional Small Craft Advisory
headlines. Calmer conditions return for the weekend as high
pressure settles over the region.

&&

Hydrology...
as of 315 PM EST Wednesday...

River flood warnings remain in effect for Stony Creek on the
Nottoway, and Mattoax on the Appomattox, Lawrenceville on the
Meherrin and Sebrell on the Nottoway. Expect additional rises
and possible warnings on local rivers given the expected
rainfall Thursday.

&&

Tides/coastal flooding...
as of 415 PM EST Wednesday...

Issued high surf advisories along the entire coast on Thu.

Strong surge of east/NE winds on Thu will bring cause tidal
departures to rapidly increase Thu morning. However, tidal
departures are currently minimal (and actually negative in upper
portions of the bay). Thus, even with 1.5 to 2 ft rises in
departures from current levels, most locations will only
approach or just barely get to minor flood thresholds. The high
tide of concern will not be until Thu aftn (or perhaps the
following tide early Fri morning for the ocean side of the Maryland
eastern shore). Will continue to watch trends overnight and Thu
morning but have not issued any coastal flood advisories at this
time.

&&

Akq watches/warnings/advisories...
Maryland...Flood Watch from 7 am EST this morning through this evening
for mdz021>025.
High surf advisory from 10 am this morning to midnight EST
tonight for mdz025.
Wind Advisory from 10 am this morning to 7 PM EST this evening
for mdz024-025.
NC...Flood Watch from 7 am EST this morning through this evening
for ncz012>017-030>032-102.
High surf advisory from 4 am early this morning to 7 PM EST
this evening for ncz102.
Wind Advisory from 4 am early this morning to 1 PM EST this
afternoon for ncz017-102.
Virginia...Flood Watch from 7 am EST this morning through this evening
for vaz048-060>062-064>069-075>090-092-093-095>100-
509>525.
Winter Weather Advisory until 10 am EST this morning for
vaz048-060-061-509.
Wind Advisory from 7 am this morning to 4 PM EST this
afternoon for vaz095-098-100-525.
High surf advisory from 4 am early this morning to 7 PM EST
this evening for vaz098.
High surf advisory from 10 am this morning to midnight EST
tonight for vaz099-100.
Wind Advisory from 10 am this morning to 7 PM EST this evening
for vaz099.
Marine...Gale Warning until 10 am EST Friday for anz650-652-654.
Gale Warning until 7 PM EST this evening for anz630>636-656-
658.
Small Craft Advisory until 7 PM EST this evening for anz637.
Gale Warning until 4 PM EST this afternoon for anz638.

&&

$$
Synopsis...mrd
near term...alb
short term...mrd
long term...eri

National Weather Service Glossary of Abbreviations