Scientific Forecaster Discussion
fxus61 kakq 131136
Area forecast discussion
National Weather Service Wakefield Virginia
636 am EST Wed Dec 13 2017
markedly colder air spreads across the region through this
evening, with temperatures moderating for late week into the
Near term /through tonight/...
latest weather analysis reveals sfc low pressure over eastern
Maine sliding toward Atlantic Canada. Associated sfc cold front
now well offshore of the eastern Seaboard this morning. To the
south, 1026+mb sfc high pressure continues to build across the
deep south toward the Tennessee River valley. Aloft, latest upper air
analysis shows strengthening upper trough taking on a negative
tilt, as it slides offshore of the mid- Atlantic coast and lifts
across the northeast into New England. Weak shortwave ridging
on its heels bringing clearing across the region this morning.
Cold and dry today, as sfc high pressure continues to build
across the southeast. Despite westerly flow aloft, and a mainly
clear sky, afternoon high temperatures will struggle to climb
into the low to mid 30s in most spots, which represent highs
~15-20 deg below normal. Expect wind chill values to linger in
the 20s through the day with winds gusting up to 20-30 mph this
morning before gradually diminishing late.
Precip chances nudge up (slightly) tonight with the latest in a
series of clipper systems sliding from the Ohio Valley into the
northeast. Models remain in good agreement that this feature
will push along and north of the region, with model timing a
bit faster at 00z than 12z. Have maintained a 20% of rain/snow
showers over the lwr Eastern Shore, mainly for a passing rain/snow
shower this evening. Could see a brief flurry/sprinkle farther
south into central Virginia this evening, but have kept pops aob 14%
with chances of measuring quite low even on cams. Otherwise,
look for an increase in clouds this aftn through evening, with
clearing late. Not quite as cold with early morning lows 25-30
inland, lower 30s se coast.
Short term /Thursday through Friday night/...
mostly clear/dry conditions persist for Thu with temps
moderating. Highs mainly in the mid/upr 40s under a partly
cloudy sky. Early morning lows in the low to mid 20
inland...upper 20s to low 30s at the coast.
Models are a bit flatter with the upper level flow for the
Friday system. As such, expect any significant quantitative precipitation forecast to be well
off to our north. Will hang on to a slight to low end chance pop
across the Maryland lower Eastern Shore for now, but would expect any
impacts to be minimal given model trend towards a more zonal
pattern aloft. Highs upper 30s to low 40s north...45 to 50
Long term /Saturday through Tuesday/...
high pressure builds back into the region for Saturday and
Sunday leading to dry conditions and a warming trend with
temperatures climbing into the mid to upper 40s on Saturday and
into the 50s on Sunday. Another system approaches the region
during the day on Sunday bringing another chance of rain Sunday
into Monday. Temperatures continue to moderate into early next
week with highs in the mid to upper 50s on Monday and Tuesday
and lows in the upper 30s to lower 40s.
Aviation /12z Wednesday through Sunday/...
cold front now offshore this morning. West winds have diminished
a bit before sunrise but should increase slightly and remain
gusty through mid aftn, W/gusts to 20-25 kt expected. Otherwise
expect VFR conditions all sites through the 12z taf period.
Outlook: expect VFR conditions to then prevail for much of the
week ahead. Some mid to high clouds expected by early this
evening, associated with next clipper to cross north of the
terminals tonight into early Thu. Low chance of a few flurries
at sby Wed evening, with another low chance on Friday.
Otherwise, dry with VFR conditions for much of the latter half
of the week into the weekend. Rain chances pick up again by late
Sunday/early Monday ahead of next system approaching from the
gale warnings remain in place through this afternoon (4pm) due to
west-northwest winds remaining elevated in the wake of last evening's cold
front. Gusts between 35-40 kt will be common. Kept the local rivers
(except the lwr james) in strong Small Craft Advisory with gusts up to 30 kt. Seas 5-
7 ft, with 3-5 ft waves.
Expect the gales to be replaced with scas this afternoon through
midday Thursday, as the gradient relaxes a bit ahead of the
next weaker cold front approaching from the west. Some guidance
does indicate the potential for gale gusts (~35 kt) across the
outer coastal waters tonight. Confidence in this remains low at
this time. Seas build back to 5-6 ft; waves 3-4 ft.
Next cold front crosses the waters by Thursday afternoon but with
weak cold air advection behind it lending to sub-Small Craft Advisory conditions through Friday.
Next system skirts the coast Friday night with Small Craft Advisory conditions
potential exists for some low water issues during thurs tide cycles
given the gusty offshore flow (w-sw).
Marine...Small Craft Advisory until 4 PM EST this afternoon for
Gale Warning until 4 PM EST this afternoon for anz630>634-638-