Scientific Forecaster Discussion
fxus61 kakq 221903
Area forecast discussion
National Weather Service Wakefield Virginia
303 PM EDT sun Sep 22 2019
surface high pressure pushes farther offshore of the mid-Atlantic
coast tonight and Monday. A weak cold front will push across
the area Monday night, with high pressure rebuilding over the
area Tuesday through midweek.
Near term /until 6 am Monday morning/...
as of 305 PM EDT Sunday...
Latest analysis reveals ~1024mb sfc high pressure centered
offshore of the mid-Atlantic coast, and ridging SW back inland
across the Carolinas and the deep south. To the northwest, a
strong cold front stretched from the upper Midwest back into the
central and southern High Plains at 19z. Mainly sunny conditions
over the coastal plain, with partly to mostly sunny conditions
inland, as some sct cumulus has popped up well inland along the
developing Piedmont leeside trough. A very warm, dry day with
late aftn highs in the low 90s inland/mid to upper 80s along
Clouds erode quickly this evening with loss of heating. Mostly
clear, dry, and mild this evening on a light S-SW flow. Lows in
the low-mid 60s over srn Virginia/inland NE NC with mid-upper 60s north
Short term /6 am Monday morning through Tuesday night/...
as of 255 PM EDT Sunday...
Sfc high pressure remains in control offshore into the deep
south to begin the day. Meanwhile, upper level ridging gets
dampened by upper shortwave crossing from Lake Superior to srn
on/qc, as the trailing cold front approaches the local area.
Another very warm/hot day expected on Mon W/ SW winds and partly
to mostly sunny conditions. Pops remain aob 10% the day, with
aftn highs in the low 90s inland/upper 80s at the coast (went
abt a category above higher end of the guidance envelope given
persistent dry conditions. Forecast dew points Mon aftn are
only in the upper 50s west of I-95, with mid 60s closer to the
Overall, guidance is slightly slower with the approaching front.
Expect front crosses the mountains Mon afternoon into early
evening, which may throw a bit more significant cloudiness into
the Piedmont by late in the day. There is a slight chc of a
shower across the northwest Piedmont sunset Monday night. The
(weakening) front is progged to cross the area from northwest to southeast
Mon night. The best upper level dynamics will stay well to our north
as the front crosses the County Warning Area. In addition, dew points will be
lower when compared to our typical Summer fropas (leading to
marginal instability at best). Therefore, have confined any
mention of thunder to the ern shore (from 00-06z). Have
maintained 20-30% pops...highest north/NE (for mainly showers). Kept
pops aob 14% for south central Virginia into interior NE NC. Lows Mon
night range from around 60f northwest to the upper 60s southeast.
Clearing out and not warm nor as humid Tue as winds turn northwest
ahead of weak sfc high pressure building east through the Ohio
Valley. Highs mainly in the low 80s, with some upper 70s
possible on the ern shore. Clear skies and light winds expected
Tue night as the high becomes centered just west of the County Warning Area. Cooler
with lows in the mid-upper 50s inland/low 60s near the immediate
Long term /Wednesday through Saturday/...
as of 255 PM EDT Sunday...
Strong sub-tropical ridge looks to persist through the period.
This will result in (continued) dry wx and temperatures
remaining aoa normal through latter half of the week. High
pressure will slide offshore to begin the period on Wednesday,
with return flow resuming later Wed/Thu. There is a small
chance for showers with a weakening front approaching by later
Thu/early Fri...but chances of accumulating pcpn are quite low
and pops have accordingly been held under 14%.
Highs Wed in the u70s/l80s east to mid 80s inland...mainly 85-90f
Thu...in the l80s at the coast and m80s inland then from 80-85f
at the coast to the M-u80s inland Fri/Sat. Lows in the l-m60s
Wed night and M-u60s for the remainder of the period.
Aviation /19z Sunday through Friday/...
as of 200 PM EDT Sunday...
VFR/dry conditions expected through the 18z taf period. South-southwest
winds continue 9-12kt this afternoon under a mostly clear sky.
Mostly clear conditions persist tonight and W/ SW winds
diminishing to 5-7kt.
Outlook...mainly VFR conditions expected from Mon-Thu. A cold
front crosses the area late Monday night into Tuesday morning.
There is a 30% chc of showers with the frontal passage at sby. For the
remaining terminals, the chc of pcpn less than 20%. High pressure
then builds over the region through Thursday.
as of 350 am EDT Sunday...
Sfc high pressure will remain centered off the NC coast
today/tonight and will gradually weaken while moving farther
offshore on Monday. No headlines today with winds currently
around 10 kt from the west/SW and 1-2 ft waves in the Bay with
coastal seas 3-4 ft. Winds are expected to shift more to a
southerly direction this aftn in response to another Lee trough
developing in the Piedmont. The winds are also likely to
increase to ~15kt in the Bay and 15-20kt over the coastal
waters by late aftn and especially late tonight into Monday.
Wind gusts may occasionally reach Small Craft Advisory threshold for oceans
zones off the Maryland coast (25 kt) and in the Chesapeake Bay
(20kt) late tonight through Monday morning. Decided to refrain
from raising any headlines as this event will be very marginal
though later shifts may need to issue a short fused Small Craft Advisory for some
of the area if winds gust consistently in the Bay at 20kt+ and
for seas out near 20nm reaching 5 ft for the northern coastal
waters. In any event, seas will avg 3-4 ft S and 4-5 ft north by
Monday with waves in the Bay building to 2-3 ft.
A cold front will approach the area from the northwest late Monday
night and cross the region early Tuesday morning. Winds will
shift to the northwest and briefly increase to 15-20 kt with higher
gusts behind the front as deeper mixing develops with a
drier/cooler airmass moving in from the north. Winds should then
decrease to north/northwest 5-10 kt by Tue aftn. A modest secondary surge
of northwest winds may develop Tue evening before winds diminish Wed
am. Winds will remain light and variable Wednesday as the sfc
high moves slowly off our coast. Winds will once again turn
south on Thursday as a front approaches the area once again at
the end of the week.
kakq radar has returned to service.