Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

369
FXUS61 KLWX 101407
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1007 AM EDT Sat Oct 10 2026

.WHAT HAS CHANGED...
The leading edge of some light rainfall is ahead of schedule as
it nears I-64 this morning. Otherwise, continue to monitor the
12Z high-resolution guidance for expected rainfall on Sunday as
well as degree of severe weather/tornado threat.

&&

.KEY MESSAGES...
- 1) Remnants of Hurricane Isaias to bring rain, breezy to
  windy conditions, and the threat of tornadoes Sunday.

- 2) Above normal temperatures Tuesday will fall the second
  half of the week as moisture starved fronts move through.

&&

.DISCUSSION...
KEY MESSAGE 1...Remnants of Hurricane Isaias to bring rain, breezy
to windy conditions, and the threat of tornadoes Sunday.

Although the remaining circulation from Isaias is still down
across Georgia, the extent of this system extends well to the
north. While a longstanding high cirrus shield remains overhead,
some weak to modest radar returns are evident south of I-64.
While there is still low-level dry air to contend with, expect
the column to saturate in time. Otherwise, the forecast remains
on track (read below for more information).

Hurricane Isaias is forecast to move north toward the TN Valley
today as it weakens and eventually loses all of its tropical
characteristics. The mid-level circulation strengthens and becomes a
large cutoff low later tonight. To the east, surface high pressure
over the Northeast today moves offshore off southern New England
tonight.

The interaction of Isaias` remnants to the west and surface high to
the east will create a large area of convergence / broad frontal
zone over the Mid-Atlantic. There is good model agreement that rain
steadily moves from south to north this evening into tonight as
forcing for ascent increases with some mid-level height falls in
response to the approaching cutoff low. It`ll take a bit of time for
the surface to truly saturate, so any rain late afternoon to this
evening in Central Virginia is going to be light. Eventually,
tropical moisture with PWATs at or above 2" surges in after
midnight.

It is worth mentioning again that conditions are favorable for a
widespread soaking rain, and 00Z models have responded with more QPF
across the region. Forcing for ascent increases tonight, and
especially Sunday morning into Sunday afternoon as mid-level heights
fall with the approach of the cutoff low. Enhanced low-level
convergence and moisture transport will peak Sunday morning into
early Sunday afternoon. Strengthening easterly flow into the Blue
Ridge could also produce enhanced rain amounts due to orographic
effects. As a result, forecast rain amounts have increased to 1.5-
2.5", with locally higher amounts of 3-4" possible. No Flood Watch
issued with this forecast update as the heaviest rain is forecast to
occur in areas that can handle it, but will continue to monitor the
latest guidance today.

Another noticeable trend in the 00Z guidance is the higher
probabilities for severe weather Sunday afternoon. The main
synoptically forced rain moves north of the area early Sunday
afternoon. Rapid height-falls and increasing low-level winds provide
a few hour window where some breaks in the clouds area possible,
leading to pockets of instability. A surface wave of low pressure
moves right through our area Sunday afternoon. Forecast soundings
indicate large, swooping hodographs, with ample shear in place  to
support organized severe convection. Clusters of thunderstorms
develop along the leading edge of the surface low pressure, with
tornadoes and damaging wind gusts as the main threats (looks mostly
to be east of the Blue Ridge). The NAM12, RRFS, and 06Z HRRR all
show this scenario. The big question still remains how much
instability actually develops. SPC has introduced a Slight Risk for
Sunday just to our south, with a Marginal Risk north to the MD/PA
border.

The strong mid-level circulation is going to bring windy conditions
to the Alleghenies and Blue Ridge, starting late tonight into Sunday
morning. Wind Advisories have been issued for downsloping easterly
winds in the Alleghenies (western Garrett, western Grant, and
western Pendleton Counties), and the Blue Ridge. The current
forecast for peak wind gusts is 40-50 mph in the Alleghenies/Blue
Ridge and 20-30 mph elsewhere.

The remnants of Isaias push offshore Monday, bringing an end to any
lingering showers. While conditions return humid and warm Monday,
there likely won`t be much in the way of shower activity due to
subsidence behind the departing trough.


KEY MESSAGE 2...Above normal temperatures Tuesday will fall the
second half of the week as moisture starved fronts move through.

Brief ridging in the wake of the tropical remnants may bring high
temperatures Tuesday to near 80 degrees. Low pressure passing north
of the area will send a cold front southward Tuesday night. Most of
the rain likely remains across Pennsylvania, although some showers
may sneak southward. Showers will also be possible along the
Allegheny Front. There`s still some significant model spread on the
progression of this front during the middle of the week, with a
large spread of temperatures possible on Wednesday. However, the
general trend will be downward for the second half of the week. A
wave of low pressure or cold front may approach toward the end of
the week which could bring some rain, but model spread remains high
on the details.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions prevail through this evening, then conditions
deteriorate tonight into Sunday as the remnants of Hurricane Isaias
impact the region. IFR conditions are likely to overspread all
terminals late tonight through Sunday afternoon, as periods of rain
and gusty winds cross the region. There could be a few hour period
of thunderstorms Sunday afternoon, some of which could be severe,
though this threat is greatest east of the Blue Ridge. Conditions
improve Monday morning, with the return of VFR conditions. Northwest
winds gusting around 20-25 knots possible Monday afternoon.

VFR conditions are most likely Tuesday and Wednesday. A dry cold
frontal passage Tuesday night may be followed by gusty northwest
winds Wednesday.

&&

.MARINE...
Marine conditions are expected to deteriorate tonight through Sunday
night as the remnants of Hurricane Isaias move across the Mid-
Atlantic. SCA conditions develop this evening in the central
Chesapeake Bay, then across all the waters tonight. The strongest
winds, gusts around 30 knots, will occur Sunday morning. Special
Marine Warnings may be needed Sunday afternoon for thunderstorms
capable of producing strong wind gusts and waterspouts. The remnants
of Isaias move offshore Monday morning, but SCA conditions continue
through Monday evening due to gusty northwest winds in its wake.

Sub-SCA conditions are likely Tuesday with brief high pressure. SCA
conditions are possible in southerly flow Tuesday night and
northwesterly flow on Wednesday as a cold front pushes through.

&&

.TIDES/COASTAL FLOODING...
Widespread tidal flooding is likely during the Sunday afternoon to
evening high tide cycle. Several conditions are coming together to
produce a surge of water up the Chesapeake Bay and Potomac River.
Strong onshore winds coming during the highest of the daily tides,
which happens to coincide with the New Moon are going to produce
minor tidal flooding at most forecast locations. A Coastal Flood
Watch has been issued for Annapolis where Moderate tidal flooding is
possible. Water levels quickly decrease Monday morning as offshore
winds follow.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory from 1 AM to 11 PM EDT Sunday for MDZ008.
     Coastal Flood Watch from Sunday afternoon through Sunday
     evening for MDZ014.
     Wind Advisory from 8 PM this evening to 11 AM EDT Sunday for
     MDZ509.
VA...Wind Advisory from 2 AM to 11 AM EDT Sunday for VAZ507-508.
WV...Wind Advisory from 8 PM this evening to 11 AM EDT Sunday for
     WVZ501-505.
MARINE...Small Craft Advisory from 1 AM to 11 PM EDT Sunday for
     ANZ530>533-535-536-538>542.
     Small Craft Advisory from 7 PM this evening to 11 PM EDT
     Sunday for ANZ534-537-543.

&&

$$

DISCUSSION...ADS/BRO/KRR
AVIATION...ADS/KRR
MARINE...ADS/KRR
TIDES/COASTAL FLOODING..KRR