Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRNK 260828
Area Forecast Discussion
National Weather Service Blacksburg VA
428 AM EDT THU MAY 26 2016
High pressure staying off the coast through Friday with typical
summer like weather impacting us increasing humidity. This weekend,
a potential tropical low may arrive toward the South Carolina coast
and linger in the general area into early next week.
.NEAR TERM /THROUGH TONIGHT/...
As of 350 am EDT Thursday...
Moisture to continue to increase today with a weak upper trough
moving across. Should see an increase in cloud cover with a threat
for showers and storms more in the afternoon and into the evening.
Still coverage to stay more scattered. Will see a few showers this
morning across the mountains. Looks like activity will wane after
dusk with most places dry after midnight.
Highs today will range from the upper 70s to lower 80s mountains,
to the mid to upper 80s east. Tonight will maintain persistence with
lows in the lower to mid 60s. Fog may be an issue where it rains
this afternoon and evening as well as in the river valleys.
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 400 am EDT Thursday...
Broad...weak upper ridging will be over the region Friday into
Saturday...with a broad and highly diffluent upper low across the
western and central U.S. A deep conveyor belt of Gulf moisture
will be tracking northward through the southern and central Plains
through the period with a continued active severe convective
pattern there. For our region...steering currents will be weak
and dynamics fairly non-existent. The disturbance that will
result in increased diurnal convection Thursday...will have moved
into New England by Friday...leaving little triggering mechanism
to work with Friday. However...a very moist summerlike atmosphere
will be present across the region with PWATS in around 1.5 inch.
Scattered convection should develop...especially across the
Alleghanys and western mountains in association with differential
heating. Areas east of the Blue Ridge should continue to see the
least chance for convection...owing to subsidence along the
western periphery of a developing tropical system across the
The remainder of the forecast period continues to hinge heavily on
the track...intensity...and duration of a tropical system
developing across the Bahamas. The GFS remains very aggressive
with this system...tracking what appears to be a true...tropical
warm core system northwest and inland toward northwest NC. PWATS
approach 2.0 inches...well above normal values...per the GFS.
Meanwhile...most of the other models keep the core of the system
near or just off the SC/NC coast...but do depict tropical moisture
spiraling inland away from the core into our region by Sunday. The
GFS solution would bring heavy rain into the CWA and arouse
flooding concerns...while the other models suggest much less
potential...barring a predecessor rain event (PRE). Will need to
watch closely...but the consensus among most models is for
scattered to numerous showers/thunderstorms by Sunday across the
region...especially east of the Blue Ridge...requiring at least
high chance pops for now. It will not be widespread continuous
rain event...but largely diurnally driven.
Humidity levels will definitely be on the increase through the
period and overall it will feel very muggy and summerlike with
mild to warm nights and warm/humid days. Looks for lows mainly in
the 60s with highs in the 80s...70s mountains.
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 415 am EDT Thursday...
Forecast challenge through the period will continue to depend on
the track of an area of tropical low pressure across the southeast
states. As noted above...the GFS brings this system well inland
into the GA/SC/NC region and leaves it lingering across the region
through the period thanks to a stagnant upper atmospheric pattern
with an upper high to our north and a broad upper low continuing
in the western U.S. Therefore...if the tropical system does drift
into the GA/SC/NC area as the GFS suggests...it will likely linger
for several days with non-existent steering currents and blocked
upper flow. Rainfall may become a concern as a result. The ECMWF
continues to paint the least ominous solution, keeping the bulk of
the precipitation and higher PWATS closer to the coast. At a
minimum, we can expect scattered diurnal convection with
warm/humid conditions through the period. Chance to high chance
pops are in order through the entire period. Max temps will remain
mostly in the 70s mountains and 80s elsewhere, with lows mainly in
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
As of 140 AM EDT Thursday...
Generally VFR conditions expected through the TAF valid
period...with a few exceptions...mainly in the form of early
morning fog in some of the mountain valleys/BCB/LWB. Expect some
mid and high cloud debris from showers and thunderstorms well to
the west of the region. Medium confidence that this cloud cover
will not be enough to hamper fog formation.
A short wave ejecting from a broad upper low over the southwest United
States moves northeast Thursday, bringing a better opportunity
for showers and a few storms to over the mountains and across
areas east of the Appalachians Thursday afternoon. MVFR ceilings
and visibilities are likely in any of these storms. Coverage will
be limited enough to just have VCTS in the TAFs for now.
Wind flow through Friday will be out of the southwest with the
weather pattern more reflective of summer conditions, primarily
VFR except for widely scattered afternoon and evening showers
during the peak heating part of the day. Nightime fog also
possible in the mountain valleys, but mainly after midnight up
until an hour or two after daybreak.
Potential wind flow change is advertised by the models this
weekend per development of a storm system off the southeast
Atlantic Coast. Models differ quite a bit on timing and movement
of this feature so low confidence forecast beyond Saturday attm.