768
FXUS61 KRNK 170922
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
522 AM EDT Thu Jul 17 2025

.SYNOPSIS...
The weather pattern will remain very warm and muggy with a daily
threat of showers and thunderstorms. There is a marginal risk
of severe storms this afternoon, in addition to storms which may
produce localized flash flooding. Near seasonal summer heat and
humidity will persist.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 400 AM EDT Thursday...

Key Messages:

1) Seasonal summer heat and humidity persists.

2) Another round of afternoon and evening showers and storms.

3) Flood watch from 2PM-Midnight for West Virginia, and for
Virginia and North Carolina primarily along and west of I-77

Large scale weather pattern has remained unchanged with a
stagnant upper level ridge of high pressure centered off the
east coast of Florida, and a quasi-stationary front from the
northern Mid-Atlantic through the Midwest and into the central
Plains. Our forecast area resides on the northern periphery of
the upper level ridge, and well south of the surface front
leaving us in a soupy summery airmass. Mean winds aloft increase
the farther north you go into NoVA and northern WV, and more of
a stagnant wind flow profile the farther south you go into the
Carolinas. In some respects this is typical of summer anyway
with flat ridging, or deamplified flow across Lower 48. Since
the pattern is stuck, whatever you had yesterday and the day
before becomes the forecast for today and tomorrow...aka
persistence.

Even with a stuck pattern, there are still subtleties that lead
to daily differences with respect to the weather. A storm may or
may not form in the same location, so the best we can do attms
is to say, just listen for the thunder. With respect to timing,
the greatest CAPE occurs during the peak heating of the day, so
that is a no-brainer with respect to airmass thundershowers...
wait for High Noon, then look to the sky for cloud build-ups.
From that point on, each thunderhead is like watching a game of
Pac-Man, gobbling up the available CAPE (pac-dots) until the
game is over at the end of the day.

For today, expect more of the same, but watch out for the
subtleties that will make it different from yesterday. Radar
trends from last night have generally validated the upper level
wind structure with faster storm movement across our northern
CWA compared to the south. This is problematic in the since
that outflow boundaries originating from the stationary front
to our north enter the CWA and then become aligned E-W with
time. One such boundary entered the CWA around midnight and now
appears to be aligned with the southern Blue Ridge close to the
VA/NC border. This will be an area to watch for early storm
initiation this afternoon and potential for training of
thunderstorms along this boundary. Another area to watch, is the
stationary front to our northwest. Convective allowing models
indicate storms will develop near this boundary over the Ohio
Valley then move east with the mean wind and into our
northwestern CWA during the late evening and early tonight.

Storms associated with both boundaries may become organized,
thus supporting at least a marginal risk for severe storms this
afternoon and evening...yielding isolated damaging winds. The
atmospheric moisture profile has remained unchanged with PWATs
near 2 inches, so storms will be rain efficient, supporting rain
rates of 2-4 inches an hour. Any storm that lingers, backbuilds,
merges or trains with others will lead to excessive rainfall
leading to flash flooding. Areas which are forecast to have the
greatest coverage today have been placed under a flood
watch...2PM-Midnight.

There is a ghost area that stands out in some of the convective
allowing models showing a QPF minimum today. Usually when winds
are westerly aloft there is enough downslope drying on the lee
side of a mountain range to inhibit storm development and
minimize CAPE. Both the HRRR and NamNest suggest the Shenandoah
Valley may be one of these voids today... so my guess is this
is where to look for Blinky, Pinky, Inky, and Clyde.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 200 AM EDT Thursday...

Key Messages:

1) Confidence is high for showers and thunderstorms each afternoon
with the highest odds during Friday and Saturday.

2) Warm and humid conditions will continue throughout the weekend.

A frontal boundary should reach the Appalachian Mountains on Friday
but stall due to a broad upper level ridge over the Southeast. This
boundary could slowly retreat northward during the remainder of this
weekend. However, the abundant moisture and instability will combine
with orographical and synoptic lift to produce scattered showers and
thunderstorms each afternoon. Coverage of these storms appears more
notable during Friday and Saturday. Any of the stronger storms pose
a risk of heavy rainfall that could lead to localized flash
flooding, wet microbursts that may blow down trees and power lines,
and frequent cloud-to-ground lightning. Temperatures do not change
much overall during this timeframe, but they could trend slightly
lower due to more widespread cloud cover and ongoing convection.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 200 AM EDT Thursday...

Key Messages:

1) Confidence is moderate for scattered showers and thunderstorms
each afternoon.

2) Slightly cooler air may arrive on Tuesday, but the atmosphere
will remain quite moist.

The models depict another frontal boundary approaching from the
northwest by Monday before stalling somewhere across North Carolina
during Tuesday and Wednesday. The flow could swing around towards
the east and allow temperatures to trend downward a little on
Tuesday as high pressure tries to wedge against the eastern slopes
of the Blue Ridge. The atmosphere will remain quite moist, so
scattered showers and thunderstorms may still redevelop each
afternoon across the mountains through the middle of the week.
However, the chances of convection may decrease in coverage and
intensity if the easterly flow becomes strong enough to advect more
stable marine air from the Atlantic Ocean.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
As of 500 AM EDT Thursday...

Mostly VFR conditions expected to prevail until cloud build ups
lead to scattered showers and thunderstorms this afternoon
with MVFR or lower ceilings in the vicinity of thunderstorms.
Until confidence on coverage of storms increases, will use VCTS
for the TAFs this afternoon. Winds today are expected to be a
little stronger across the Virginias with sustained speeds
8-12kts and some gusts near 15 kts attms out of the west or
southwest. Thunderstorm gusts may exceed 25 kts.


.EXTENDED AVIATION OUTLOOK...

The overall pattern remains stagnant for the remainder of this
week with a warm and humid air mass providing daily chances of
afternoon showers and thunderstorms and an overnight potential
for patchy fog. In general, conditions expected to be VFR for
most of this week with the exceptions being the aforementioned
afternoon storms and overnight fog which will result in tempo
sub-VFR conditions.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch from 2 PM EDT this afternoon through this evening
     for VAZ007-009-010-012-015-016-032.
NC...Flood Watch from 2 PM EDT this afternoon through this evening
     for NCZ001>004-018>020.
WV...Flood Watch from 2 PM EDT this afternoon through this evening
     for WVZ042>044-507-508.

&&

$$

SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...PW
LONG TERM...PW
AVIATION...PM