Scientific Forecaster Discussion
fxus61 kakq 160838
Area forecast discussion
National Weather Service Wakefield Virginia
338 am EST Mon Dec 16 2019
a slow moving front will become nearly stationary
across the area today. A low pressure system crossing the mid
Atlantic region Tuesday will drag a cold front across the area late
Tuesday into early Wednesday. High pressure returns for the end of
Near term /until 6 PM this evening/...
as of 330 am EST Monday..
Early this morning, a weak area of high pressure is settled NE of
the area while a nearly stationary boundary is draped near the
Virginia/NC border. Some returns on radar have been noted just to the
north of the area this morning, but it appears much of this is not
making it to the ground at this time. Do however expect
precipitation chances to increase across these areas over the next
couple of hours. Temperatures this morning generally range from the
upper 30s to lower 40s (some mid 30s SW where clearing occurred.)
Still looking at a tricky temperature forecast today that will be
highly dependent on where the stationary front decides to set up
shop. For now, sided closest to the NAM which tends to handle this
kind of situation the best along with a blend of some high-res model
guidance. This forecast has the front largely staying south of the
Richmond Metro today, positioned from around central Lunenburg
County to south of Petersburg to around Norfolk. North of the
boundary temperatures will only make it up into the lower to mid 40s
(perhaps struggling to make it out of the upper 30s across the far
northwest until late) while south of the boundary, highs will be in the
upper 50s to upper 60s. There will likely exist a pretty substantial
temperature gradient from north to S right across the Richmond Metro
Precipitation-wise, it still appears that the bulk of today's precip
chances will stay confined to the northern third of the forecast
area. Low precip chances for the remaining forecast area (roughly
ric south). Precipitation may start out as a mixture of rain/snow,
across the far northwest (northern Louisa/Caroline counties) and northern
portions of the Maryland Eastern Shore. Quantitative precipitation forecast amounts are expected to remain
light and surface temps a few degrees above freezing, thus am not
expecting accumulation/significant impacts from this. Any wintry
precip should come to an end across these areas shortly after
Short term /6 PM this evening through Wednesday night/...
as of 330 am EST Monday...
Tonight, the front will begin to makes its slow progression back to
the north as a warm front as low pressure tracks from the Tennessee Valley
to the mid-Atlantic. Temperatures should remain fairly steady and
then rise as the front tracks northwest. Early lows will range from the
upper 30s northwest to the mid 50s S. Rain chances increase area-wide
through the night into the morning hours ahead of the associated
cold front that will cross western portions of the area Tuesday
afternoon and exit offshore Tuesday night. The previously mentioned
warm front should make it north of most of the forecast area by
Tuesday afternoon (a little less certainty across the far nw). With
the front north of the region, the area will be in the warm sector
with highs climbing into the low to upper 60s (70 across the far s).
For the far north/NW, have highs making it up into the mid to upper 50s.
Finally, there will be a touch of instability across the far southeast by
Tuesday afternoon/evening, thus would be not be shocked if we get a
rumble or thunder or two with the cold frontal passage, but not high
enough confidence to include in the forecast at this time.
Conditions improve quickly Tuesday night after the cold frontal
passage and high pressure building back into the region through
Wednesday. Modest cold air advection and clearing skies should drop temps to the
20s northwest to the low/mid 30s southeast. High pressure remains in control
during the day Wednesday, allowing for dry conditions/sunny skies
but chilly temperatures. Did not stray too far from the nbm with the
Wednesday high temperature forecast and have highs in the mid to
upper 40s. Cold Wednesday night with high pressure over the region,
lows will generally be in the 20s area-wide, potentially upper teens
across the northwest.
Long term /Thursday through Sunday/...
as of 230 PM EST Sunday...
High pressure remains in control Wednesday through Friday. This will
result in dry weather and slightly below normal temps during this
period. Low temps Thursday and Friday in the low 20s, near 30
at the coast, and high temps in the 30s/40s. Overnight model
runs had a coastal developing over the southeast and riding up the
Atlantic coast next weekend. 12z runs of the GFS and European model (ecmwf) today
have a low developing over the eastern Gulf and then slowly
drifting off the southeast coast over the weekend, while the CMC still
tracks the low up the Atlantic coast. With the high uncertainty
this far out, just went with low chance pops for next weekend.
Aviation /09z Monday through Friday/...
as of 1230 am EST Monday...
VFR conditions at all sites to start the 06z taf period with
some scattered to broken mid-level clouds (especially northern half of
the area) around ~10k feet. Kric may reach MVFR conditions
Monday morning due to cloud bases around 3000 feet due to a
stationary boundary lingering across the area. Ksby will likely
fall to MVFR by late Monday morning or afternoon with -ra
showers and remain MVFR for the majority of the day on Monday
into Monday night. Winds will be light and variable to calm
Sunday night. South of a stalled boundary winds will become SW
around 10 kt (mainly for kphf/kecg/korf)
Outlook...Tuesday has the potential for degraded flight
conditions due to low clouds and rain across all airports ahead
of a cold front which passes through the region Tuesday evening.
High pressure builds Wednesday with VFR conditions returning.
as of 330 am EST Monday...
A backdoor cold front dropped swd along the mid-Atlantic
coast and has settled near the Virginia/NC border early this morning. The
wind is NE 10-15kt north of the boundary, with seas generally 2-3ft,
with up to 3-4ft offshore north of Chincoteague, and ~2ft waves in the
Bay (although some areas of 2-3ft are possible early this morning).
The boundary gradually lifts nwd this morning into early aftn, with
the wind becoming E, the se, and even S from the Lower Bay swd with
speeds aob 10kt. The boundary sharpens and creeps back swd late this
aftn and evening, with the wind becoming north-northeast for the Middle Bay and
NE off the Maryland coast while remaining S to the south of the front, again
with speeds aob 10kt. The boundary retreat back nwd late this
evening through the overnight hours, with the wind becoming southeast the S
and increasing to 10-15kt. The boundary is forecast to lift north of the
region Tuesday morning into early aftn as a strong cold front
approaches from the NW, with the wind becoming SW 15-20kt, with 3-
4ft seas, and 2-3ft waves in the Bay. There is a potential for pre-
frontal scas, but it is still early to issue any flags as there is
some uncertainty with respect to the onset and extent.
The cold front is expected to cross the coast late Tuesday aftn and
evening, with a period of strong cold air advection occurring by Tuesday night with
a north-northwest wind increasing to 20-25kt with gusts up to 30kt. There is a
potential for gusts to 35-40kt with 3-5mb/3hr pressure rises with
the initial surge, but the current thinking is that the duration for
stronger gusts will be less than 3hrs and more on the order of an
smw rather than a gale watch/warning. A secondary cold front and
another round of cold air advection are expected by Wednesday night a north-northwest wind
again increasing to 20-25kt with gusts up to 30 kt. Seas are
expected to build to 4-6ft Tuesday night and again Wednesday night,
with 3-4ft waves in the Bay. Small Craft Advisory conditions are likely to prevail
Tuesday night through early Thursday, with perhaps a lull during the
day Wednesday. High pressure returns Thursday aftn into Friday.