Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
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FXUS61 KRNK 210528
Area Forecast Discussion
National Weather Service Blacksburg VA
128 AM EDT Wed Sep 21 2016
An upper low combined with the remnants of former Tropical Storm
Julia will meander about eastern North Carolina and South Carolina
through late week before finally shifting out into the Atlantic
ocean. This will keep fairly unsettled conditions east of the Blue
Ridge over the next several days, less so in western areas. High
pressure will gradually build in from the west during the later
half of the week. A backdoor cold front drops south through the
area later Saturday followed by cooler high pressure Sunday into
.NEAR TERM /THROUGH TODAY/...
As of 945 PM EDT Tuesday...
Have trimmed back probability of precipitation to southeast of
Danville for late this evening with a slight chance of rain
gradually spreading to a Farmville to Yadkinville line by
An upper level low over the southeastern states is expected to pull
the remnants of Julia back south into the North Carolina coastal
piedmont tonight. Some models move remnants into South Carolina,
some into the the interior portion of North Carolina. Subsidence
and dry air intrusion in the northwest quadrant of this system
will keep the northwest counties of the forecast area dry.
Temperatures tonight will remain mild across the piedmont where
thick clouds blanket the area. Elsewhere, clear skies will lead
to some river valley fog, but mixing should deter widespread
dense fog from forming. Opposite trend for daytime temperatures
with cooler than normal conditions expected across the piedmont
with thick cloud cover. Elsewhere, at or above normal temperatures
under partly cloudy skies.
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
As of 309 PM EDT Tuesday...
Closed low over the Southeast coast will interact with the post
tropical remnants of Julia during the period. The challenge in the
weather forecast is the degree to which the richer moisture on the
northern side of this system gets advected into parts of our
Isolated to scattered showers are possible Wednesday night across
southern portions of the forecast area. Low temperatures Wednesday
night will range from the mid 50s in the mountains to the
mid 60s in the Piedmont.
The trend of the ecmwf is further east with low and starting to
weaken in more of an open wave feature similar to GFS. In any case,
the unsettled weather with scattered convection may continue
Thursday into Thursday night across the south and southeast portion
of forecast area. Higher confidence in drier weather under sunshine
across the north on Thursday. High temperatures Thursday afternoon
will vary from the lower 70s in the southern mountains to around 80
degrees in the Piedmont. Clear to partly cloudy conditions will
prevail Thursday night with readings from the mid 50s in the west to
the mid 60s in the east.
By Friday into Friday night, the closed low will transition into an
open wave and progress further eastward into the Atlantic ocean.
Drier air will push into our area and push all the precipitation out
of the area. High temperatures on Friday will climb into the mid 70s
in the west to the mid 80s in the east. The combination of light
winds and low level moisture under a mostly clear skies will result
in areas of river and mountain valley fog Friday night into Saturday
morning. Low temperatures Friday night will general be from the mid
50s in the west to the mid 60s in the east.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 130 PM EDT TUESDAY...
Strong upper ridging centered along the Mississippi River to start the
weekend will gradually get pinched back to the southwest as a rather
high amplitude troughing regime develops over the northeast U.S. by
early next week. This will allow increasing northwest flow aloft to
take shape across the region between the departing 500 mb ridging and
eventual upper level low pressure over New England. Within this setup
should a rather strong backdoor cold front drop south through the area
later Saturday followed by cooler high pressure Sunday into Monday.
This before yet another cold front arrives from the northwest on
Tuesday with the next stronger mid level shortwave. However deeper
moisture looks quite limited with both frontal passages given a dry
west/northwest flow aloft so only including slight shower pops later
Saturday west and again Tuesday. Low level flow turning more
east/northeast behind the initial boundary, per the developing
wedge could allow for a slight uptick in shower coverage southern
sections Saturday night, although iffy for much more than
clouds/sprinkles at this point per lower amplitude/drier
Should see high enough heights ahead of the weekend front to keep warm
temps in place Saturday with highs mostly in the upper 70s to mid 80s.
Subsequent rounds of decent cool advection look to arrive with each
frontal passage into late Tuesday with potential for Sunday into Monday
to remain quite cool if clouds are more widespread. This timing
continues to vary between solutions as each may be too strong, although
thinking highs mostly 70s Sunday-Tuesday, with 50s for lows and
possible 40s valleys Monday morning with high pressure overhead.
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --As of 120 AM EDT Wednesday...
MVFR ceilings are approaching KDAN from the east and forecast
soundings suggest by 09z that ceilings will be around 1500 ft.
LYH should also be dropping to around 3000 ft by 09z. Elsewhere
ceilings stay VFR. Across the mountain taf sites, fog may become
an issue again, but not as much as last night per drying that took
place today. Still expect some periods of LIFR to IFR at BCB/LWB
The upper low will continue to stay near the coast of NC Wednesday
with a few showers stretching toward DAN but more times will be
dry so not impact taf sites yet. The MVFR ceilings should lift by
mid morning with gradient picking up, so gusty winds will be
possible as far west as BCB, mainly in the 15 to 25 kt range at
Winds should subside by 22-00z with VFR continuing through
Extended aviation discussion...
Thursday and Friday, outside of late night/early morning fog/low
clouds, expect mainly VFR conditions. The slight chance of showers
will remain just east of KLYH and KDAN through Thursday night.
GFS/ECMWF have been consistent in filling and lifting out the low
to the northeast on Friday.
A back-door cold front will come through the Mid-Atlantic region
on Saturday. High pressure will build in for Sunday. The chance of
precipitation or any sub VFR conditions will increase through the
day Sunday and into Sunday night.
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