Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
000
FXUS61 KLWX 040800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Tue Oct 4 2022

.SYNOPSIS...
An upper level low will remain centered overhead today as a
coastal low continues to churn offshore. These features will
finally begin to move off toward the east Wednesday afternoon,
allowing high pressure to move back in for Thursday. A cold
front will pass through the area either Friday or Friday night.

&&

.NEAR TERM /THROUGH TONIGHT/...
The upper level low which has impacted our weather over the last
several days will remain overhead today, while an associated
coastal low continues to spin away offshore. This pattern will
result in yet another day of dreary conditions, with ample low
cloud cover, rain, and well below normal temperatures. In fact,
most of the local climate sites will likely set new record low
high temperatures for the date. For further details, see the
climate section below.

Current radar imagery shows that most of the rain is located
over MD and VA (along and north of I-66/US-50), as well as
extreme eastern portions of the WV Panhandle. This same region
will continue to be the most favored region for rain through the
remainder of the day into tonight. However, a few showers may
make it further south and west. Northeast MD should see the most
persistent and heaviest precipitation, with the Baltimore area
potentially receiving over an inch of additional rainfall
through tonight. Rain rates won`t be overly intense, so hydro
issues aren`t expected. If any instances of flooding were to
occur, they`d likely be of the nuisance/poor drainage variety.
Temperatures will exhibit very little in the way of a diurnal
cycle today, with temperatures holding in the mid 40s to lower
50s for most through tonight.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The aforementioned upper level low and associated coastal low
will finally ever so slowly start to drift eastward during the
day tomorrow. That being said, their influence will still be
felt, with lingering showers to the east of the Blue Ridge
during the morning hours. A fair amount of cloud cover will also
remain in place, with some clearing from west to east during the
mid-late afternoon. Temperatures will be a bit warmer, but still
below normal, with highs in the mid 60s for most.

A weak ridge of high pressure will build into the area at the
surface on Thursday. At upper levels, a potent trough will dig
into the Upper Great Lakes, while a weaker lead shortwave
approaches the area from the west. This lead disturbance
shouldn`t have much of an impact on our sensible weather, other
than producing some high clouds. Skies should be most sunny
across the area, with much warmer temperatures, as warmer air is
drawn northward ahead of the approaching upper trough. Highs on
Thursday will reach into the mid 70s for most.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Conditions remain mild to finish out the work week. A strong cold
front tracks through the region on Friday with post-frontal
downsloping flow in the wake. Expect highs to top out in the low/mid
70s with breezy west-northwesterly winds. This boundary is largely
moisture starved although a few showers are not out of the question
across the Alleghenies. The cold air advection with this system does
not become evident until Friday evening and into Saturday. A number
of models depict 850-mb temperatures dropping to the 0 to -3C range.
Consequently, the coolest day during the extended forecast period
will be on Saturday with highs in the upper 50s to low 60s. A number
of mountain locations should struggle to escape the 40s.

The impact of these chilly temperatures will be most evident
overnight, particularly on outdoor vegetation. As the growing season
is still going, there is a decent chance for a widespread frost or
freeze both Friday and Saturday nights. Initially this focuses
across the Alleghenies before expanding into the Blue Ridge
mountains and adjacent mountain valleys by the following night. A
seasonably strong surface ridge (1028-1030 mb) settles in from the
Ohio Valley into the Mid-Atlantic. Depending on how this potential
freeze pans out, a number of these locations could see a conclusion
to the growing season. Surface high pressure remains over the region
on Sunday maintaining cool, dry conditions. Mid/upper heights begin
to rebound into early next week which allows for temperatures to
moderate. Highs are expected to return to the upper 60s by Monday,
but with continued dry weather and abundant sunshine.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Conditions are VFR at the terminals early this morning. Ceilings
are expected to drop to MVFR at all sites except CHO today. DMH
and BWI may eventually go IFR later this afternoon into the
overnight hours. Gradual improvement in ceilings is expected
through the day tomorrow, but MVFR ceilings may linger through
at least the morning. VFR conditions are expected tomorrow night
through Thursday. Periods of rain today will become more
showery in nature tonight into tomorrow morning, with dry
conditions moving in tomorrow afternoon. Winds will be gusty out
of the north both today and tomorrow.

Breezy westerly winds are anticipated behind the midday Friday cold
frontal passage. These gradually turn more northwesterly into the
night and Saturday. Such winds may gust up to 20-25 mph during the
afternoon hours. Expect VFR conditions with dry weather.

&&

.MARINE...
Northerly winds will persist over the waters through Wednesday
as a coastal continues to churn away off the Atlantic Seaboard.
Gales are in effect through this evening for the middle and
lower portions of the Bay, as well as over the Lower Tidal
Potomac. SCAs are in effect elsewhere. SCAs are in effect for
all waters tonight through tomorrow. SCA level winds may linger
over the wider waters through tomorrow night. Sub-SCA winds are
expected on Thursday.

In response to the cold front, breezy west to northwesterly winds
are expected across the area waters. At this point, the wind
strength should fall in the category of Small Craft Advisories
Friday afternoon into Saturday. Conditions remain dry with high
pressure building in from the west.

&&

.TIDES/COASTAL FLOODING...
It`s a highly uncertain and dynamic situation with water levels in
the Chesapeake Bay right now with strong northerly winds. The north
end of the bay has blown out fairly well (most notably at Havre De
Grace in Harford County with tidal levels staying between 0 and -1
feet), but anomalies of 1.5-2 feet have piled up at the mouth of the
bay. The northerly winds should keep higher anomalies confined to
the south end of the bay for a time, but as offshore low pressure
drifts away and winds slowly decrease, there could be a significant
snapback. How much anomaly returns northward is very uncertain,
although most guidance is not predicting anything more than minor
flooding. However, that anomaly won`t likely decrease too much until
a cold front arrives Friday, so there could be multiple cycles near
minor flooding during the second half of the week.

&&

.CLIMATE...
Record cool high temperatures may be set Tuesday. Below are
records for October 4th.

Washington DC area: 56 (set in 1998)
Baltimore MD area: 54 (set in 2010 and 1998)
Sterling/Dulles VA area: 56 (set in 2010 and 1998)
Martinsburg WV area: 54 (set in 1998)

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ530-531-
     535-536-538-539.
     Gale Warning until 6 PM EDT this evening for ANZ532>534-537-
     540>543.
     Small Craft Advisory from 6 PM this evening to 6 PM EDT
     Wednesday for ANZ532>534-537-540>543.

&&

$$
SYNOPSIS...KJP
NEAR TERM...KJP
SHORT TERM...KJP
LONG TERM...BRO
AVIATION...BRO/KJP
MARINE...BRO/KJP
TIDES/COASTAL FLOODING...BRO/DHOF
CLIMATE...DHOF


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.