Harrisonburg, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

897
FXUS61 KLWX 121910
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
310 PM EDT Sat Sep 12 2026

.WHAT HAS CHANGED...
Showers and thunderstorms continue to develop and expand in
coverage near and west of the Appalachians as well as over
southern Virginia into North Carolina.

&&

.KEY MESSAGES...
- 1) Widespread convection expected through tonight, while
  turning cooler and drier into early next week.

- 2) Seasonably warm & dry conditions anticipated early next
  week ahead of a cold front.

&&

.DISCUSSION...
KEY MESSAGE 1...Widespread convection expected through tonight,
while turning cooler and drier into early next week.

The current setup features a stalled surface boundary still sitting
just south of the Virginia-North Carolina border as of mid
afternoon, with a warm front slowly approaching the Appalachians
from the southwest. This is bounded by a modest area of high
pressure drifting offshore of New England. At the same time, a
shortwave trough is swinging into the upper Ohio Valley. As
this trough axis pushes off toward the east, models continue to
show a low-level response of enhanced moisture/theta-e
advection. With surface to 850-mb winds shifting to mainly south
to southeasterly, precipitable water values will further rise
in time. Increasing isentropic lift atop the poleward advancing
boundary should set the stage for convection through tonight.

The 12Z high-resolution model suite shows two possible areas of
more widespread convective development. (1) As depicted in the
12Z HREF 40-dBZ paintball plots, supported by regional radar
imagery as of mid-afternoon, the more pronounced activity forms
across West Virginia up into western Pennsylvania. As these
cells encroach on the Allegheny Front, the slow-moving nature of
such storm elements coupled with saturated soils (per
satellite) could afford a flash flood risk in the vicinity of
western MD into the overnight hours. (2) Additionally, the warm
conveyor belt along the I-95 corridor will likely be an
additional focus area for storm genesis, as is currently taking
place in southern VA. This may occur more into the evening
hours locally as this activity is driven by instability
along/south of the warm front. How this convection interacts
with development coming off the Alleghenies will determine the
risk of flash flood potential along the I-95 corridor. High-
resolution model depictions of this evolution still feature
quite a bit of spread, but the signal bears watching, especially
given the notably more aggressive 12Z NAM12.

Depending on instability and storm evolution, the mentioned
convective complexes could fester into tonight. A preponderance
of solutions favor shifting this activity into northeastern
Maryland by around 4-7 AM (early Sunday). Patchy fog could
materialize in the wake, particularly for areas seeing some of
the heavier rainfall.

For Sunday into Monday, multiple temperature swings are
expected. Ahead of the approaching cold front, some weak
downslope component to the wind fields should steer highs well
into the 80s on Sunday. As this front crosses during the
diurnal minimum in heating (i.e., overnight Sunday/early
Monday), storm chances will be rather limited. Will maintain
showers and a few rumbles of thunder along the Alleghenies, with
lower (but not quite zero) probabilities further east across the
piedmont. Monday`s forecast features prevailing northwesterlies
with afternoon gusts up to 15 to 25 mph. High temperatures
should range from the mid 70s to low 80s, while being locally
cooler in the mountains. This also comes with falling humidity
and cool temperatures on Monday night. Robust surface high
pressure crossing the northeastern U.S. will support widespread
50s overnight. Even some upper 40s are likely in spots that can
fully decouple and remain cloud-free.


KEY MESSAGE 2...Seasonably warm and dry ahead of a mid-week cold
front.

High pressure will continue to build on Tuesday as mid-level dry air
moves in from the Great Lakes. Expect seasonable and dry
conditions to persist during this time as highs reach into the
lower 80s with dewpoints potentially dipping into the upper 40s
on Tuesday morning.

Strong upper-level ridging builds toward the area Tuesday into
Wednesday, then begins to break down by late in the week as a
retrograding low tracks south into the Florida Peninsula from
the Atlantic. Humidity likely begins to increase again on
Wednesday as any lingering dry air is driven east out of the
region. Meanwhile, a trough will begin to develop over the
Northern Plains with a stemming cold front tracking east through
the Mid-Atlantic sometime in the mid-to-late week period.
Updated model guidance has delayed the arrival of this front
potentially to Thursday & into Friday, with showers &
potentially a few thunderstorms accompanying the front. However,
significant uncertainty remains in the time of arrival here as
models continue to grasp this synoptic setup. Regardless,
severe probabilities continue to look low as we begin to
transition out of the summertime thunderstorm season.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Increasing shower coverage likely holds off until the evening
to overnight period. It remains to be seen whether this is
accompanied by a risk of thunderstorms. Will maintain a mention
of PROB30 thunderstorms at KCHO, but will await additional
guidance to expand this threat northward. Locally heavier
rainfall this evening into the night could lower conditions to
IFR at times. Once showers exit into northeastern Maryland, a
mixture of MVFR to IFR ceilings are expected for all sites.

Despite starting off with restrictions on Sunday morning, expect
improvements through the day with numerous breaks in the clouds.
VFR conditions are likely for the remainder of Sunday into
Monday. Northwesterly winds increase on Monday behind a strong
cold front with afternoon gusts possibly reaching 25 knots.

Prevailing VFR conditions are expected to continue at terminals
Tuesday through Thursday. A few showers forming ahead of a cold
front on Thursday evening could bring temporary reductions.
Winds generally flow between 5-10 knots southerly to southeasterly.

&&

.MARINE...
Enhanced channeling effects will result in gusts around 20 knots
are of the southeast for the middle/lower tidal Potomac, tidal
Patuxent, Tangier Sound and the Chesapeake Bay main channel from
North Beach MD to Smith Point VA into the evening. Small Craft
Advisories may need to be expanded up the bay/extended into the
late evening. Additionally, showers increase in coverage toward
the evening and especially the overnight hours. The most likely
area to see thunderstorms would be south of U.S. 50. It remains
to be seen how far north instability can reach.

Sub-advisory winds are expected for Sunday before a stronger
surge of northwesterlies ensue behind a cold front on Monday.
Widespread advisory-caliber wind gusts are likely which will
necessitate Small Craft Advisories.

Winds likely remain below SCA thresholds Tuesday through Thursday,
shifting NE Tuesday to SE Wednesday, then S by Thursday.

&&

.TIDES/COASTAL FLOODING...
Strengthening onshore flow will bring tide levels up across the
area through tonight. Some locations could reach Action Stage
tonight/early Sunday. Annapolis could near Minor. A cold front
moves through by early Monday which should bring an end to any
coastal flooding potential.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Flood Watch until 2 AM EDT Sunday for MDZ501-509-510.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ533-
     534-536-537-542-543.

&&

$$

DISCUSSION...BRO/DHOF/SRT
AVIATION...BRO/DHOF/SRT
MARINE...BRO/DHOF/SRT
TIDES/COASTAL FLOODING...LWX