Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
737 am EDT Sat Oct 22 2016
high pressure will build east from the lower Mississippi Valley
today as strong low pressure remains over New England. This
pattern will bring breezy northwest winds through this afternoon.
The high will become centered across the southeast states Sunday
into Monday, bringing dry conditions with seasonable temperatures
to the local area.
Near term /through tonight/...
current analysis indicates cold front now well off the coast, with
a sfc trough crossing the local area. A few isolated showers
passing through southern Virginia/northeast NC, and another batch
persists over the Eastern Shore/Northern Neck so will carry
scattered shower wording there through 15z. Skies are still
mostly cloudy, but clearing from SW to NE will continue through
the rest of the morning hrs. Temperatures will hold in the 50s
most areas through noon, skies become mostly sunny except for
some lingering clouds across the NE this morning. Much cooler
conditions prevail under strong cold air advection...high temps only in the low-
mid 60s. Winds will be highest along the NE zones where sustained
winds will average 20-30 mph with gusts of 30-40 mph. Farther
inland and across the southern coastal zones, gusts will average
25-30 mph. Winds then decrease tonight as sfc high pressure builds
east from the lwr MS valley. Quite chilly tonight, and W/ low dew pts
expect a rapid fall in temperatures later this evening. Sfc high
stays centered well SW of the region however, so this is not an
ideal radiational cooling setup despite the dry air and clear
skies. Guidances has trended a little colder and have lowered mins
tonight into the upper 30s to low 40s well inland (primarily along
and west of the I-95 corridor). This is where winds likely fall
off/decouple after 06z. Patchy frost possible, though dew pts may
be too low for much to develop. Farther east, expect lows mainly
in the mid-upper 40s as winds remain somewhat elevated even
Short term /Sunday through Tuesday/...
a fairly deep upper low remains over eastern Canada sun-Mon, with
another shortwave diving east-southeast around the base of this upper low
from the Great Lakes through New Jersey Mon morning. Sunny on Sunday with
highs mainly 65-70 f. Not as cool Sun night due to some return SW
flow ahead of a dry cold front with lows in the mid-upper 40s
interior S to the upper 40s/lower 40s near the coast and across
the north. The front pushes through the local area Mon shifting the
winds back to the northwest in the afternoon. However, downslope warming
will keep the cold air advection to our northwest through the aftn with highs into the
mid 70s south and central to around 70 f across the north. Mostly
sunny skies prevail (partly sunny across the ne). Cooler Mon night
with lows in the upper 30s/lwr 40s west to near 50 f southeast. Highs Tue in
Long term /Tuesday night through Friday/...
strong/1030mb Canadian high pressure builds south across the area
tues then slowly shifts east to a position off the New England
coast Wed. Continued dry but cool. Lows Tue nite in the upper
30s/low 40s to upper 40s southeast. Highs Wed in the low to mid 60s. Lows
Wed nite in the mid 40s to lwr 50s.
Low pressure tracks from the nations mid section Wed into the gt
lakes region thurs. An assctd warm front progged to lift north-northeast across
the mts and into PA Thu. Best support for pcpn with this feature
remains north of the fa but European model (ecmwf) does show some weak lift as far
south as Virginia late thurs / thurs nite. GFS a bit slower spreading the
moisture east of mts. Kept low chc pops across northern half of fa
during this time frame. Highs thurs 65-70. Lows thurs nite in the
50s. Warm Fri with highs in the upr 60s to mid 70s.
Aviation /12z Saturday through Wednesday/...
as of 12z...the sfc cold front has shifted well offshore, but
strong upper low centered over central PA/New York state continues to
bring enough instability aloft across NE sections of the County Warning Area this
morning for scattered showers through 15z that may affect ksby,
with variably cloudy skies/VFR cigs of 4-10 k ft elsewhere. Skies
become mostly sunny by 14 to 15z or so (remaining mostly cloudy
through 18z at ksby).
Gusty northwest winds can be expected through the aftn all sites as
the low pressure system over the northeast states intensifies.
Gusts of 25 to 30 knots can be expected toward the coast and at
ric through about 21z today. Diminishing winds/mainly clear skies
overnight all areas (some gusts to 20 knots at ksby still expected
Outlook...high pressure builds across the southeast Sunday. A
dry cold front sweeps across the area Monday, with high pressure
returning Tuesday and Wednesday. VFR conditions dominate.
the well advertised cold front will move farther offshore this
morning with high pressure returning late today into tonight. Northwest
winds behind the front have already reached Small Craft Advisory levels early this
morning and still expecting winds to increase to gale force thru the
morning hours. Strongest gusts up to 40 kt still look to be across
the northern coastal waters and middle ches Bay with gusts to 35 kt
across the south. Winds expected to drop below gale on the ches Bay
and coastal waters south of Parramore this afternoon and will be
replaced by scas at that time. Still anticipating a secondary
surge/increase in mixing this evening, so have maintained gale/Small Craft Advisory
headlines into tonight.
The offshore northwest flow will keep seas from building to much higher
than 5-7 ft most areas (highest out 20 nm offshore). Bay waves build
to 4-5 ft. Winds remain elevated on Sunday but should diminish to
some extent and avg 15-20 knots by afternoon. The next front crosses
the area Mon. Appears another surge (albeit much weaker) will likely
require Small Craft Advisory headlines late Sunday into Monday.
National oceanic and atmospheric administration wx-radio transmitter at driver/Norfolk is offline (see pns
Marine...Small Craft Advisory until 4 am EDT Sunday for anz633-635>638.
Gale Warning until 4 PM EDT this afternoon for anz630>632-634-
Gale Warning until 2 am EDT Sunday for anz650-652.