Scientific Forecaster Discussion
fxus61 klwx 191901
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
301 PM EDT Sat Oct 19 2019
high pressure over the Delmarva will shift offshore through tonight
as Post-tropical cyclone Nestor moves through the southeastern U.S.
And toward the Carolinas on Sunday. The remnants of Nestor will move
offshore of the Outer Banks by Sunday evening. A cold front will
approach from the Ohio Valley Monday, then cross the region Tuesday.
High pressure will follow for Wednesday through Friday before
another cold front approaches by Saturday.
Near term /tonight/...
high pressure centered over the eastern half of the County Warning Area and the
Delmarva Peninsula this afternoon will migrate offshore through
tonight. Post-tropical cyclone Nestor made landfall near St. Vincent
island Florida this afternoon, and it will continue tracking
northeastward through tonight. Plenty of upper level clouds have
streamed over the region this afternoon as Nestor moves into the
southeastern U.S. Clouds will continue to increase and thicken
overnight, with the remnants of Nestor bringing rain to central
Virginia by daybreak. Overnight temperatures will remain mild with
the increased cloud cover and weak warm air advection, holding in
the middle 40s to lower 50s.
Short term /Sunday through Monday night/...
periods of rain will continue to spread across the area from
southwest to northeast Sunday morning, with the heaviest rainfall
expected to fall over southern/eastern Virginia and southern Maryland. The rain
will come to an end around midday or early afternoon on Sunday as
the core remnants of Nestor track off the Outer Banks. Have favored
the higher side of guidance in terms of qpf, painting 0.50-0.75"
along and south of the district, with a half inch or less further
north and west. Up to an inch to an inch and a half will be possible
across portions of central VA, the Northern Neck, and across
southern Maryland. With plentiful cloud cover and elevated rain chances,
temperatures won't budge much from the upper 50s to near 60 degrees
Clouds try to break Sunday night as a drier northerly wind prevails
in the wake of Nestor, which could result in patchy fog across the
area. Lows will bottom out in the 40s to near 50 degrees. High
pressure builds over the area Monday and Monday evening, before
shifting offshore, promoting near normal temperatures and dry
conditions. A cold front will near the Ohio Valley Monday night,
increase shower chances by early Tuesday morning. For now, will
advertise chance pops into the predawn hours Tuesday mainly west of
the Blue Ridge. Lows Monday night will be mild in the 50s.
Long term /Tuesday through Saturday/...
a strong cold front will push across the region Tuesday, bringing
rain showers nearly everywhere. High temperatures should be in the
middle to upper 60s during the day.
There will be a chance for lingering showers Tuesday evening, prior
to a ridge of high pressure building into the region overnight
Tuesday through Wednesday night. Slightly cooler and drier air will
accompany the high. Tuesday night's low temperatures should bottom
out in the upper 40s. Wednesday's high temperatures will be lower to
The high moves east to and off the East Coast Thursday and Thursday
night. A return flow around the west side of the high will bring
slightly more humid and warmer conditions into the region Thursday
and Thursday night. Highs Thursday could reach the lower 70s with
lows near 50.
On Friday into Friday night, the deterministic models are in
generally good agreement with another cold front approaching from
the northwest. A chance for rain showers late Friday into Friday
night appears to be the flavor. Highs Friday middle to upper 60s
with a possible influence from cloud cover.
Aviation /19z Saturday through Thursday/...
VFR conditions at the terminals through the first half of the night
under a light southerly flow. The remnants of Nestor will near the
Carolinas Sunday morning, bringing periods of rain and low cigs to
the terminals through midday Sunday. MVFR/IFR conditions forecast
during this timeframe. Rain exits east of the terminals Sunday
afternoon, however low cigs will persist into Sunday evening. Drier
northerly winds will allow for improving conditions Sunday night,
with patchy fog possible. High pressure will build over the
terminals Monday and Monday evening with VFR conditions expected. A
cold front will approach from the west late Monday night, bringing
the chance for showers to iad/mrb/cho by daybreak Tuesday, with sub
VFR conditions possible.
MVFR conditions Tuesday into Tuesday evening due to rain showers at
the terminals. Winds southeast 5 to 10 knots with higher gusts,
shifting westerly around 10 knots Tuesday night. VFR conditions
Wednesday and Wednesday night. Winds west 5 to 10 knots with higher
gusts Wednesday afternoon, becoming southwest around 5 knots
Small Craft Advisory conditions expected to develop over the waters late tonight as
the remnants of Nestor nears the Carolinas and the gradient
increases. Winds will remain near Small Craft Advisory through the day on Sunday,
perhaps nearing gale conditions across the southern Bay and tidal
Potomac waters Sunday afternoon and early evening. Winds will
finally abate late Sunday night into Monday morning as high pressure
builds over the waters through Monday night, with sub Small Craft Advisory conditions
Small craft advisories possible Tuesday night into Wednesday morning
with frontal passage and building high pressure from the west. Winds
southeast 10 to 15 knots Tuesday, shifting west 10 to 15 knots gusts
up to 20 knots Tuesday night into Wednesday morning. Winds mainly
west around 10 knots later Wednesday into Wednesday night.
southerly winds have commenced over the area this afternoon and we
are seeing anomalies rise to around a half a foot. The current
forecast maintains only action stage being reached at our sensitive
sites, however minor flooding is not out of the question at
Annapolis with this evenings high tide cycle. Water levels are
expected to remain elevated Sunday night into Monday as southerly
breezes pick back up again ahead of an approaching cold front late
Monday night into Tuesday, with minor flooding thresholds more
likely to be met as anomalies near 1-1.5 feet.
District of Columbia...none.
Marine...Small Craft Advisory from 10 am to 10 PM EDT Sunday for anz531-
Small Craft Advisory from 1 PM to 6 PM EDT Sunday for anz530-
Small Craft Advisory from 7 am Sunday to midnight EDT Sunday
night for anz532-533-541-542.
Small Craft Advisory from 4 am Sunday to 6 am EDT Monday for
Small Craft Advisory from 10 am to 4 PM EDT Sunday for anz536.