Clifton, Virginia Weather

170
FXUS61 KLWX 091918
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
318 PM EDT Fri May 9 2025

.SYNOPSIS...
A cold front will slowly drift south of the area today while low
pressure moves northeastward along the Upper Mid-Atlantic coast.
High pressure will track in on Saturday before a secondary cold
front pushes through on Sunday morning. High pressure then
returns into early next week. Low pressure will approach from
the southwest Tuesday through Thursday next week bringing
unsettled conditons.

&&

.NEAR TERM /THROUGH TONIGHT/...
The latest surface analysis indicates the earlier cold front has
settled off to the south and east. More specifically, this
boundary stretches from the Virginia Tidewater region up across
the Delmarva Peninsula into the southern coast of New England.
Locally, dew points remain in the 50s to low 60s which suggests
the true surge of drier air has not moved through the area yet.

Any ongoing convective activity is focusing along the leading
edge of the upper trough. This is evident on the GOES-19 multi-
layer water vapor channels which features a rather tight
moisture gradient. A preponderance of the shower activity has
begun to exit off to the southeast away from Albemarle County.
Otherwise, a few stray showers are pivoting across northeastern
Maryland. Area-wide trends are favoring drier conditions as
evidenced by the clearing skies from west to east. Those west of
the Blue Ridge Mountains are mainly seeing a mixture of cumulus
and stratocumulus fields. These fair weather clouds should
gradually shift their influences to locations off to the east.

There is a discernible spread in afternoon temperatures across
the region. For those along and east of U.S. 15, thick cloud
cover has held temperatures down in the upper 50s to low 60s.
Farther west across the Shenandoah Valley, increasing sunshine
should help push these areas closer to the mid/upper 60s. The
usual cool spot is along the Alleghenies where highs are in the
upper 40s to mid 50s.

As this frontal system pulls away, gradients remain rather tight
owing to the strong trough overhead. Northwesterly winds remain
breezy through the evening with gusts up to 20 to 25 mph. High
pressure does approach from the Ohio Valley overnight, but its
influence on wind fields remain uncertain at this point. The
Allegheny Front is closest to this anticyclone which suggests
these areas have the best shot of seeing lighter winds
overnight. Most notably, this would be across the Allegheny
mountain valleys which typically decouple more easily. Given the
colder and drier air mass moving in, these Allegheny locations
will likely see some frost development. Consequently, Frost
Advisories are in place starting at 2 AM tonight from Highland
County northward to western Garrett County. While these areas
should see low temperatures in the mid 30s, most others can
expect readings in the 40s. The only exception would be the
central Shenandoah Valley which is forecast to drop into the
mid/upper 30s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Expect a dry forecast across the area this weekend. On Saturday,
the area of high pressure slowly moves in from the west while a
deep low inhabits coastal New England. The combination of these
pressure systems will encourage an increase in northwesterly
winds. Model soundings show decent boundary layer mixing up to
around 850-mb. With forecast temperatures at this level around
5-7C, highs should rise into the low 70s given such dry adibatic
profiles. A few spotty mid 70s are possible farther south
toward the I-64 corridor and across the Shenandoah Valley.
Heights will continue to build aloft as a longwave ridge tracks
through. Subsidence in this pattern will favor mainly sunny
skies for Saturday, but with northwesterly gusts to around 20 to
25 mph.

Mid/upper moisture content increases into the night which should
afford some uptick in cloud cover. High pressure also begins to
break down overnight as a secondary cold front dives down from
Ontario. Low temperatures on Saturday night should fall into the
mid 40s to mid 50s.

Heading into Sunday, this cold front exits the area during the
early to mid morning hours. Given the limited moisture in the
atmosphere, this will be a dry frontal passage. 500-mb heights
further rise into Sunday, generally on the order of 582 dm vs.
562 dm today/Friday. Despite the mainly northerly flow,
temperatures are expected to further warm well into the 70s,
perhaps near 80 degrees. This is accompanied by a mix of clouds
and sun. Some clouds linger into the overnight hours which
raises low temperatures into the upper 40s to 50s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
By Monday, a large upper level low will be centered over the Lower
Mississippi Valley. Broad upper ridging will reside to the north and
east of this upper low across the Great Lakes and Mid-Atlantic,
while upper troughing moves into the West Coast. At the surface, high
pressure initially located off to our north will progress eastward
off the Southern New England coastline. The aforementioned upper low
will very slowly drift northeastward over the course of the week,
potentially progressing off to our northeast by Thursday.

Dry conditions are expected on Monday, but chances for showers and
thunderstorms will increase by Tuesday and Wednesday as the upper
low approaches from the southwest. As is often the case when it
comes to upper lows, forecast confidence is low when it comes to the
details. Ensemble guidance differs substantially with respect to how
much rain will fall. Some members show multiple inches of rain,
while others show much lighter amounts. If the members that produce
multiple inches of rain were to verify, there could potentially be
some flooding concerns Tuesday into Wednesday.

Most guidance shows the upper low shearing out into an open wave as
it lifts off to our north and east on Thursday. This would lead to
decreased chances for steady rainfall, although an afternoon
thunderstorm may still be possible. Temperatures would also
increase, with high temperatures potentially making it into the
80s.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
After contending with low ceilings and numerous showers this
morning, area terminals have seen some gradual improvements
through the day. The D.C. and Baltimore terminals are still
seeing MVFR ceilings (1,500 to 2,000 feet), but these should
erode by later in the day. In the wake of a cold front,
northwesterlies may gust up to around 20 knots through early
this evening.

VFR conditions are likely for the entire weekend. Gradients
remain somewhat tight on Saturday which supports another round
of breezy northwesterly winds to around 25 knots. A secondary
cold front moves through early Sunday with light northerly flow
expected into much of Sunday.

South to southeasterly winds and VFR conditions are expected on
Monday. Sub-VFR ceilings, as well as showers and thunderstorms
appear possible Monday night into Tuesday, along with southeasterly
winds.

&&

.MARINE...
Behind the earlier cold front, a broad north to northwesterly
wind has been gusting to near 18 to 20 knots at times.
Consequently, Small Craft Advisories are in effect for the
Chesapeake Bay and lower tidal Potomac. Within the Chesapeake
Bay, the only exceptions are the Patuxent and Patapsco Rivers
which are more sheltered from these gustier winds. Winds
intensify a bit more into Saturday with northwesterly gusts up
to 20 to 25 knots. Small Craft Advisories are in place for all
waters through early Saturday evening. Winds do drop off rather
quickly with sub-advisory winds expected through the rest of the
weekend.

Sub-SCA level south to southeasterly winds are expected on Monday.
Southeast winds may near low-end SCA levels on Tuesday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 PM EDT Saturday for MDZ008.
     Frost Advisory from 2 AM to 8 AM EDT Saturday for MDZ509.
VA...Frost Advisory from 2 AM to 8 AM EDT Saturday for VAZ503-504.
WV...Frost Advisory from 2 AM to 8 AM EDT Saturday for WVZ501-505-
     506.
MARINE...Small Craft Advisory until 6 PM EDT Saturday for ANZ530>534-
     537-539>541-543.
     Small Craft Advisory from 8 AM to 6 PM EDT Saturday for ANZ535-
     536-538-542.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KJP
AVIATION...BRO/KJP
MARINE...BRO/KJP