Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Wakefield Virginia
628 am EST sun Jan 21 2018
high pressure remains centered off the southeast coast through
Monday. A cold front crosses the region Tuesday morning.
Near term /through tonight/...
weak upper level trough slides across the southeast states and off the
coast today as ridging aloft dominates from the Tennessee-Ohio valleys
to the mid-Atlantic states. Very lo prob for patchy fog early
this morning...otherwise scattered-broken clouds (averaging out mostly
sunny). Winds vrb-south-southwest aob 10 kt. Highs in the l-m50s on the ern
shore to the u50-l60s elsewhere.
Short term /Monday through Tuesday/...
sfc hi pres remains off the East Coast through Mon while lo pres
tracks from the Central Plains to the wrn lakes. South-southwest flow will
keep mild wx over the region W/ partly cloudy conditions. Lows
tonight in the M-u30s. Highs Mon 55-60f near the Bay/ocean and
on the ern shore to 60-65f for most other locations.
Rain chances increase quickly after midnight Mon night through
Tue morning as lo pres tracks through the lakes region...pushing
its associated cold front across the local area. Models now in
general agreement wrt timing that front through the forecast area. Keeping
chance to likely pops for most of the area during 06z-17z/23 (tue)
then pcpn moving out of the entire area by 00z/24 (wed). Will
also keep hidden/very lo pops for isolated tstms. Lows Mon night
from the u40s-l50s. Highs Tue from 60-65f north and on the ern shore
to the u60s-l70s S.
Long term /Tuesday night through Saturday/...
models are in very good agreement in the extended range from 00z
Wed through Saturday with the long wave trough pulling out of
the northeastern US Wed and Thursday with a shortwave ridge
building in for Friday and Saturday. At the surface, the period
begins with northwest flow as the surface low over deepens over the
nern US. The surface low will lift NE into the Canadian
Maritimes by Wed evening. With the northwest flow, expect the clouds
to clear tues night into Wednesday but with the cold advection,
temperatures will be cooler into the upper 40s to lower 50s.
Another shortwave will move through the eastern trough on
Tuesday and will bring a reinforcing cold front to the area.
This may knock temperatures down a couple more degrees on
Thursday, but with little moisture expect to see just a few
clouds across the northern portion of the County Warning Area.
High pressure will build into the area on Thursday night into
Friday. The high will remain in place through Saturday before
slowly sliding off the coast by late Saturday with SW flow
returning. This will allow for good radiation cooling both thurs
and Fri night with temps in the u 20s to l30s thurs night and
low to mid 30s Friday night. For Friday should see lots of sun
with highs around the mid 40s over lower Maryland and m50s in
southern Virginia. On Saturday with the return flow the models are
indicating return moisture getting in and some showers possible
late day, but at this point, not ready to introduce pops so have
gone with just slight chance values in the 15 to 20% range.
High should continue to modify into the 50s to around 60f.
Aviation /12z Sunday through Thursday/...
VFR conditions will continue through the 12z taf period as sfc
hi pres continues to dominate. Winds will be vrb-south-southwest aob 10 kt.
Sfc hi pres settles off the southeast coast through Mon W/ mainly and dry
conditions continuing. The next chance for widespread
precipitation and flight restrictions comes late Mon night into
Tue night with a passing cold front. High pres returns later
high pressure, centered over and just off the southeast US coast,
will remain in control of the weather thru Monday with winds 10 kt
or less and generally benign boating conditions. By Monday night,
winds will begin to increase again out of the south as a deepening
low over the Great Lakes pushes its associated cold front toward the
region. Wind will increase to 15 to 25 kt from the S-SW prior to
daybreak tues, continuing thru midday, with seas on the coastal
waters building to 4-6 ft; waves 3-4 ft on the Bay. Scas will likely
be needed. Once the front clears the area tues afternoon, winds will
shift to the west 10-15 kt tues night/Wed and then northwest on
Thursday. Waves/seas subside to 1-3 ft.