989
FXUS61 KLWX 171922
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
322 PM EDT Sat Oct 17 2026
.WHAT HAS CHANGED...
Frost/freeze coverage is trending lower tonight, especially
east of the Blue Ridge. Extended Small Craft Advisories into
Sunday. Lowered minimum temperatures and added mention of frost
Sunday night west of I-95.
&&
.KEY MESSAGES...
- 1) Below normal temperatures with frost and freeze concerns
continue through Monday morning.
- 2) A Nor`easter lurks nearby for the new workweek bringing the
potential for a few showers and breezy conditions, especially
along and east of I-95.
&&
.DISCUSSION...
KEY MESSAGE 1...Below normal temperatures with frost and freeze
concerns continue through Monday morning.
The mid level trough axis is moving across the area this
afternoon. Anafrontal rain is now exiting southern Maryland.
Drier air in the wake of the upper jet streak is seen in water
vapor imagery, with the clearing line reaching the I-95
corridor. Temperatures are holding in the 50s this afternoon,
although more sunshine and deep mixing have allowed them to warm
a few degrees higher than the previous forecast. Northerly
winds gusting 20-35 mph continue through the afternoon before
decreasing tonight.
The trends has continued tonight to keep the center of the
surface high over the upper Ohio Valley. There will be a sharper
pressure gradient on its southeastern flank due to the
developing Nor`easter off the North Carolina coast. While it was
already expected to some extent, winds remaining at least 5 mph
will likely limit how much temperatures can fall east of the
Blue Ridge. Tonight`s cold air will be driven more by advection,
although more widespread decoupling may occur west of the Blue
Ridge closer to the surface high. The elevated winds may
maintain notable temperature/dew point spreads (the latter of
which will be in the upper 20s) to prevent widespread frost
formation, especially east of the Blue Ridge. The Frost Advisory
remains in effect though, since many of these areas in the
piedmont are prone to localized decoupling. While NBM
probabilities of freezing temperatures have decreased from
yesterday, especially east of the Blue Ridge, reliable guidance
does still show pockets of freezing temperatures in the Freeze
Warning area. The highest confidence in widespread subfreezing
temperatures is in the Allegheny and Potomac Highlands, perhaps
over to the central Shenandoah Valley. So in the end, no changes
to those headlines at this time.
The high settles more directly over the area Sunday into Sunday
night, leading to lighter winds and continued dry conditions.
The pressure gradient will increase to the southeast though, so
winds may be a bit more elevated over southern Maryland. Highs
will remain below normal in the mid 50s to near 60. The
position of the high might actually lead to colder conditions in
some areas Sunday night into Monday morning, especially between
I-81 and US-15. Dew points in the upper 20s and lower 30s along
with calm winds make a case for more potential for frost and
freeze conditions west of I-95. Headline decisions will need to
wait until it is determined where the growing season will
continue after tonight.
A gradual warming trend likely starts thereafter, although
temperatures will remain below normal through Monday night.
While there is some uncertainty with the Nor`easter off the
Carolina coast, most guidance keeps it far enough to the
southeast for dry conditions to continue through Monday night.
KEY MESSAGE 2...A Nor`easter lurks nearby for the new workweek
bringing the potential for a few showers and breezy conditions,
especially along and east of I-95.
Uncertainty remains regarding a potential nor`easter developing in
the vicinity of the NC/VA coast during the early and middle part of
next week. The track of this system will dictate any rain chances,
breezy conditions, and coastal flooding risks across the region.
Current 12z guidance remains all over the place when it comes to the
placement of the low and timing as it meanders along the coast. Each
of the models form a coastal low on what was the residual upper
level trough and front from earlier in the weekend. Guidance points
to a low either along the coast of NC or 25-50 miles offshore Monday
before drifting it north toward the Delmarva and NJ coast midweek.
Some of the guidance even retrogrades the low back into southern NJ
and the Delmarva during the back half of the workweek period.
Meanwhile, 1035-1037 mb high pressure will remain wedged along
and west of the mountains Monday into Tuesday before retreating
east midweek. A secondary area of 1028-1030 mb Canadian high
pressure will follow Wednesday and Thursday as it slides east
from Ontario into New England before wedging south late week.
It`s not until next week when a front crosses the region.
Synoptically, we sit in an omega block type setup under
predominantly zonal flow. The coastal low offshore combined with the
wedging high in the east, ridging in the center part of the country,
and troughiness in the west. With that said, expect the nor`easter
to have little movement along the coast throughout the week. As the
low fills and potentially occludes Tuesday through Friday, expect
spokes of shortwave energy to pivot it along it. These spokes of
energy will drive any shower threat, especially in locations along
and east of I-95. The highest probabilities for rain (at least
20 percent) remain across southern MD, the northern neck of VA,
and perhaps northeast MD during the Monday through Friday
timeframe. Areas further west will likely remain dry with a few
passing clouds. Downsloping west of the Blue Ridge will keep dry
conditions in place throughout the week. Outside the shower
chances will be the concern for wind, marine issues, and coastal
flooding. Right now, winds look to average between 15 to 25 mph
during the Monday afternoon through Wednesday afternoon
timeframe. Highest gusts of 25 to perhaps 35 mph will be down
across southern MD and along the western shore of the Bay where
the gradient will be tighter compared to locations west. As for
marine and coastal flooding concerns see the corresponding
discussions below.
Highs temperatures will top out in the mid to upper 60s (50s
mountains) each day with overnight lows in the upper 30s and mid
40s. Overnight lows warm into the 50s late week.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
With clouds clearing to the east, the main concern for the TAFs
is the wind. Northerly gusts of 20-30 kt will subside with
sunset, although some 15-20 kt gusts may linger the first half
of the night. High pressure will build closer by Sunday into
Monday, but a nor`easter will lurk off the Carolina coast. Any
north or northeasterly gusts to 20 kt will be limited to the
daytime hours. Dry conditions will continue with few or no
clouds.
Tuesday through Saturday...Primarily VFR conditions are expected
amongst the terminals with periods of sub-VFR mainly east of BWI,
DCA, and MTN. A few showers are possible on the east side of the ZDC
airspace with the nor`easter lurking offshore. Winds will generally
be out of the northeast at 10 to 20 kts with gusts up to 30 kts,
especially near the waters.
&&
.MARINE...
Gusty northerly winds continue this afternoon in the wake of a
strong cold front. Marginal gale gusts continue south of the Bay
Bridge. The Gale Warning continues until 6 AM Sunday, but recent
trends suggest winds may drop below criteria before that point,
perhaps as early as this evening. Elsewhere, Small Craft
Advisories continue. The upper Potomac is expected to drop below
criteria late this evening, but the remainder of the waters
likely won`t see wholesale decreases in winds until sometime
Sunday morning. Locations south of the Bay Bridge and the lower
Potomac will likely keep advisory conditions most of Sunday.
Advisories were issued or extended accordingly. Advisories will
likely need to be extended into Sunday night for portions of the
waters, although the coverage will depend on the position and
strength of a Nor`easter off the North Carolina coast.
Monday through Thursday...A developing nor`easter off the Mid-
Atlantic coast will deliver a prolonged period of SCA conditions
and potential gales (mainly over the wider waters of the mid
bay). Confidence is currently low for gales based upon the track
of the system with projected winds out of the northeast at
10-20 kts with gusts up to 30 kts at times.
&&
.TIDES/COASTAL FLOODING...
After approaching near-blowout conditions in the northern bay
this afternoon, a snapback likely begins tonight as northerly
winds begin to slacken. A developing nor`easter off the Mid-
Atlantic coast will lead to tidal anomalies rising more into the
upcoming week. Sensitive locations (i.e Annapolis) will have a
chance to reach minor flooding thresholds during the high tide
cycle Sunday night and again during the middle of next week.
Considerable uncertainty remains on how exactly this Nor`easter
will track and subsequently affect the tide levels.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 11 AM EDT Sunday for MDZ008.
Freeze Warning from 1 AM to 9 AM EDT Sunday for MDZ003>006-501-
502-507-509-510.
Frost Advisory from 1 AM to 9 AM EDT Sunday for MDZ503-505.
VA...Freeze Warning from 1 AM to 9 AM EDT Sunday for VAZ025>031-
503>505-507-508.
Frost Advisory from 1 AM to 9 AM EDT Sunday for VAZ036>040-050-
051-501-502-506-526.
WV...Freeze Warning from 1 AM to 9 AM EDT Sunday for WVZ050>053-055-
501>506.
MARINE...Small Craft Advisory until 11 AM EDT Sunday for ANZ530-531-538-
539.
Gale Warning until 6 AM EDT Sunday for ANZ532>534-537-543.
Small Craft Advisory from 6 AM to 6 PM EDT Sunday for
ANZ532>534-537-543.
Small Craft Advisory until 11 PM EDT this evening for ANZ535.
Small Craft Advisory until 6 AM EDT Sunday for ANZ536.
Small Craft Advisory until 6 PM EDT Sunday for ANZ540>542.
&&
$$
DISCUSSION...ADS/EST
AVIATION...ADS/EST
MARINE...ADS/EST
NWS LWX Office Area Forecast Discussion