453
FXUS61 KLWX 080839
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
339 AM EST Fri Nov 8 2024

.SYNOPSIS...
A dry cold front over the Great Lakes will quickly dive
southeastward and cross the Mid-Atlantic by this evening. An
area of high pressure will follow for the first half of the
weekend. A frontal system with a better moisture connection to
the Gulf of Mexico will approach from the Ohio River Valley
Sunday, then cross the Mid-Atlantic Monday. A secondary cold
front will likely cross the region Tuesday into Wednesday, then
another frontal system may approach Thursday into Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The cold front that crossed the region yesterday evening has
settled into the Carolinas as of early this morning. A band of
stratocumulus clouds laid in its wake generally south of I-70.
This cloud cover should erode and slip southward pretty quickly
shortly after daybreak as drier air advects in from the north.

A secondary cold front will drop in from the Great Lakes by this
afternoon. Cool, dry advection induced by this pair of fronts
and ahead of building high pressure will result in gusty northwest
winds today. The strongest winds are most likely (1) over the
higher terrain, and (2) near and north of US-50/I-66; wind gusts
of 20 to 30 mph are most likely over these areas this afternoon,
with gusts of 15 to 20 mph lingering into the evening behind
the secondary front.

No precipitation and very little cloud cover is expected today.
When combined with the gusty winds, dropping humidity, and very
dry antecedent conditions/fuels, the threat for rapid fire
spread will exist this afternoon (see Fire Weather section).

Due to the dry northwest downsloping flow and lack of clouds,
have gone with the warmer guidance for temperatures and lower
guidance for dew points/relative humidity.

As mentioned earlier, some breezes could linger into the evening
in the wake of the secondary cold front. This will lead to a
slow but steady drop in temperatures this evening, with a
sharper drop in sheltered valleys possible late overnight as
winds go light.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
The first half of the weekend looks dry under the influence of
sprawling high pressure building from the Great Lakes and Ohio
River Valley to the Northeast and Mid-Atlantic. Temperatures
look to be right around normal for mid November.

A compact shortwave trough/upper low will eject from the mid
Mississippi River Valley to the Great Lakes on Sunday. A warm
front will lift northeastward ahead of this system`s surface low
Sunday, followed by its cold front late Sunday night into Monday
morning. Unlike many fronts recently, this one will have a
connection to the Gulf of Mexico. However, it will be running
into persistent ridging that has anchored itself near the
Eastern Seaboard in recent weeks. So, although the chance for
rain will be higher than with recent systems, it still looks
generally light in nature. Early projections are for a broad
quarter to half inch of rain (with a couple more tenths than
that along and west of the Alleghenies), but I wouldn`t be
surprised if this trended a bit drier given the front will be
battling a persistent dry ridge pattern over the area.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A progressive longwave pattern will continue across the nation which
will generally favor a frontal passage every 3 to 4 days over the
local area. A formerly potent closed low is forecast to pass by to
the north early Monday. This draws a cold front through the Mid-
Atlantic region early Monday morning. Given minimal thickness falls
behind the front, subsequent days only yield temperatures near
normal for early/mid November. Rain shower chances quickly diminish
beyond the morning hours on Monday with increasing sunshine for the
afternoon. A west to northwesterly wind will usher in drier air
through mid-week with temperatures returning to the mid 50s to low
60s, locally falling into the mid 40s to low 50s over the higher
terrain. With a strong anticyclone settling over the northeastern
U.S., expect some cooler nights, especially by Tuesday night.
Forecast lows fall into the 30s, with low 40s along and east of I-
95.

The next system in the chain brings another shot of rain showers by
Wednesday evening into Thursday. While global ensembles differ on
timing, they all agree on the passage of this trough. Some
deterministic solutions (i.e., 00Z Canadian) show some interesting
coastal low development. However, this scenario certainly appears
like an outlier at this time. Beyond this forecast period, the
Climate Prediction Center favors a mild pattern into the following
week.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
VFR stratocumulus should quickly erode from north to south
between 12Z-16Z this morning, with perhaps a brief bout of MVFR
CIGs near KCHO around daybreak. Otherwise, today looks mainly
sunny (if not SKC) with increasingly gusty NW winds. After
starting at a 330-360 heading this morning, winds likely back to
280-310 this afternoon ahead of a secondary (dry) cold front.
Gusts of 20 to 25 kts look likely for most TAF sites, but will
be lower for KCHO where the gradient will be a bit weaker.

Winds will shift to more of a due north direction in the wake of
the secondary front tonight, with the wind shift most likely to
occur just after the evening push. Gusts of 15-20 kts may linger
into the evening, perhaps as late as 03Z-06Z before gradually
subsiding overnight.

High pressure will result in VFR conditions Saturday and
Saturday night as light northerly flow turns easterly. Sub-VFR
conditions are possible Sunday especially late as a warm front
lifts across, then a cold front follows Sunday night. Scattered
to numerous rain showers are forecast during this time.

Low ceilings could linger into early Monday morning, but expect
improvement thereafter behind the cold front. Expect VFR conditions
through Tuesday with initial west-northwesterly winds giving way to
northerlies by Tuesday. Afternoon gusts may push up to around 15 to
20 knots each day.

&&

.MARINE...
Northerly flow of 5-10 knots is forecast through mid morning. An
increasing gradient ahead of a secondary cold front will cause
wind gusts to increase to around 20 knots late this morning into
this afternoon, earliest and most frequent across the northern
waters of the upper tidal Potomac River and the upper Chesapeake
Bay, where several gusts in excess of 25 knots are possible.

There may be a lull in the wind for a few hours around dusk, but
the wind will turn north and increase markedly by mid evening as
the secondary cold front drops to the south. Due to the strong
gradient and favorable northerly channeling direction, a few
gusts to near gale force can`t be ruled out over the wider/open
waters this evening. The brief window for such gusts, as well as
the fact that winds are not perfectly aligned in the lowest few
thousand feet precludes the issuance of a Gale Warning for now.

Winds will gradually subside late overnight into Saturday,
eventually dropping below SCA levels by Saturday afternoon as
high pressure builds. A warm front will lift across the waters
Sunday, followed by a cold front late Sunday night into early
Monday morning. Winds likely increase with this frontal system,
which would prompt additional SCAs. Rain showers will likely
accompany this frontal system, as well.

The cold front passes through the waters early Monday with
mainly west-northwesterly winds in the wake. Winds eventually
shift to more northerly by Tuesday. Small Craft Advisories may
be needed at times through Tuesday.

&&

.FIRE WEATHER...
A secondary dry cold front will cross the Mid-Atlantic this
afternoon. Northwest winds will increase as a result, with gusts
of 20 to 30 mph most likely over the higher terrain and near and
north of US-50/I-66. Dry air advection is expected to result in
minimum relative humidity values of 20 to 35 percent this
afternoon. Fuels continue to dry due to the recent very dry
pattern. All of this will result in an increased risk for the
rapid spread of fires this afternoon.

Even as the sun goes down, gusts of 15 to 20 mph may persist
across the higher terrain and northern/eastern areas this evening
in the wake of the front. The breezy conditions and continued
dry advection will lead to rather gradual and poor RH recovery
the first half of the night for many areas. So although elevated
to locally critical conditions are likely to abate after sunset,
locally elevated conditions could persist depending on the exact
extent of mixing and drying into the evening hours.

There may be a brief window of locally elevated fire weather
conditions late Saturday morning into early Saturday afternoon.
The potential for this is highest east of US-15 where the
gradient will be strongest, resulting in a few gusts around 20
mph as RH drops to 20 to 30 percent. Of note, very low RH around
10 percent is possible above 2000 feet due to abundant dry air a
few thousand feet above the surface. Winds will likely be less
further west over the higher terrain since the gradient will be
weaker, but if the gradient ends up a touch stronger or further
west then locally elevated conditions could develop over the
central and northern Virginia Blue Ridge on Saturday.

&&

.CLIMATE...
A record dry spell continues across the Mid-Atlantic. Below is a
list of the longest stretches of consecutive days with no
measurable precipitation observed.

.SITE..DCA, BWI, IAD, MRB have set records for longest dry days...
.DCA...Current stretch: 36 days (ending 2024-11-07)
       Previous record: 34 days (ending 2007-10-18)
.BWI...Current stretch: 36 days (ending 2024-11-07)
       Previous record: 32 days (ending 1963-10-31)
.IAD...Current stretch: 36 days (ending 2024-11-07)
       Previous record: 32 days (ending 1963-10-31)
.MRB...Current stretch: 31 days (ending 2024-11-07)
       Previous record: 30 days (ending 1988-07-09)

.NAK...Current stretch: 31 days (ending 2024-11-07) - ranks 3rd
       Record: 34 days (ending 2001-11-19)
.HGR...Current stretch: 25 days (ending 2024-11-07) - tied for 10th
       Record: 32 days (ending 1913-11-13)
.CHO...Current stretch: 35 days (ended 2024-11-06) - ranks 3rd
       Record: 43 days (ending 2000-11-08)
       CHO observed 0.03 inches of rain on Nov 07, ending the streak

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Red Flag Warning from noon today to 6 PM EST this evening for
     DCZ001.
MD...Small Craft Advisory from 10 AM this morning to noon EST
     Saturday for MDZ008.
     Red Flag Warning from noon today to 6 PM EST this evening for
     MDZ003>006-008-011-013-014-502>508.
VA...Red Flag Warning from noon today to 6 PM EST this evening for
     VAZ028-030-031-053-054-501-505-506-526.
WV...Red Flag Warning from noon today to 6 PM EST this evening for
     WVZ050>053-504.
MARINE...Small Craft Advisory from 10 AM this morning to noon EST
     Saturday for ANZ530-531-538-539.
     Small Craft Advisory from 1 PM this afternoon to noon EST
     Saturday for ANZ532-533-536-537-540>542.
     Small Craft Advisory from 6 PM this evening to noon EST
     Saturday for ANZ534-543.
     Small Craft Advisory from 10 AM this morning to 6 PM EST this
     evening for ANZ535.

&&

$$

SYNOPSIS...DHOF
NEAR TERM...DHOF
SHORT TERM...DHOF
LONG TERM...BRO
AVIATION...BRO/DHOF
MARINE...BRO/DHOF
FIRE WEATHER...DHOF
CLIMATE...DHOF