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000
FXUS61 KRNK 250508
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
108 AM EDT Tue Jul 25 2017

.SYNOPSIS...
A weak cold front will slide southeast through the area tonight
before stalling over the Carolinas Tuesday into Wednesday. High
pressure builds north of the region behind the front bringing a
return to more seasonal temperatures later tonight through mid
or late week. Another cold front approaches from the northwest
on Friday and works slowly through the area by the weekend.

&&

.NEAR TERM /THROUGH TODAY/...
As of 930 PM EDT Monday...

Lingering showers Mountain Empire/NRV will be dissipating
shortly as approaching weak frontal boundary starts moving into
the region from the northwest. Clouds will then gradually
decrease overnight and it will feel a bit more comfortable with
lows overnight in the low/mid 60s west of the Blue Ridge, upper
60s/around 70 to the east.

Previous discussion...

This front should finally slide southeast and across the region
later this evening as the upper trough to the north swings by
to the northeast. Should see clearing take shape overnight as
the front sags to the south allowing for a bit more comfortable
air to advect into the mountains where expect lows well into the
60s. Moisture may linger across the south/east so kept lows
mainly upper 60s to lower 70s there. Also despite good drying
today, appears some fog/stratus development possible espcly
valleys given heavy rain from last night and better radiational
cooling west tonight.

High pressure builds in from the north on Tuesday with weak
northerly flow resulting in enough dry advection to limit most
convection to across far southern sections at best. This seen
via model lowering of PWATS from north to south and axis of
deeper moisture well to the south closer to the residual surface
front. Therefore reduced pops to slight chance mainly across
northwest NC where perhaps enough low level moisture/instability
may linger to pop a shower or two but iffy. Otherwise enough
subsidence for overall mostly sunny skies and not quite as
hot/humid with highs low/mid 80s mountains to 87-92 east of the
Blue Ridge.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
As of 1245 PM EDT Monday...

Little change in the weather pattern and no synoptic scale forcing
Wednesday and Thursday. Will keep minimal probability of
precipitation, mainly in southern Virginia and northern North
Carolina each afternoon and evening. Persistence combined with bias
corrected MET/MAV guidance will be reasonable for daily highs and
lows.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 1245 PM EDT Monday...

Upper pattern amplifies starting on Friday with the upper ridge over
the western United States slightly retrograding and a trof digging
in the east. An upper low may eventually close off somewhere over
the Tennessee Valley or Mid Atlantic region by Sunday or Monday.
This closed low solution was not supported by a majority of the
extended guidance. Probability of showers and thunderstorms will
increase on Friday and Saturday with some vorticity advection and
lowering heights. Air mass ahead of the trough stays in the +16 to
+20 range for temperatures at 850MB and will be a little cooler on
Sunday and Monday.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
As of 105 AM EDT Tuesday...

Concerns this morning mainly focus around fog development and
possible low cloud development along the Alleghany front. Will
discuss the later first as that possibility seems limited due to
decreasing upslope W-NW flow becoming near calm or light and
variable, possibly even light northeast. Will include for now as
it remains a possibility per model soundings. Fog development
at LWB and BCB especially seems a better possibility due to
recent rainfall, hence moist ground in the area, clearing skies,
and near calm winds. Have continued earlier thinking on this
and continued potential for IFR-LIFR FG at BCB and LWB in the
08Z- 12Z time frame. Will hold off on fog elsewhere, although
MVFR BR conditions at LYH and DAN do not seem out of the
question, just not enough confidence to include at this time.

Winds will be light WSW-WNW 4-6kts this evening, becoming calm
overnight at most sites. Winds will be light and variable
Tuesday, but good potential for light northeast winds east of
the Blue Ridge.

Medium confidence in ceilings through 13Z, then high confidence
in VFR ceilings.
Medium to high confidence in visibilities through 13Z, then
high confidence in VFR visibilities.
Medium to high confidence in wind speed and direction through
the TAF valid period.

Aviation Extended Discussion...

A frontal boundary will remain stalled to our south through Wed,
with high pressure wedging southward on Wed from the northeast
U.S. Overall VFR, but with flow turning more east, this could
bring some MVFR/IFR ceilings, which should quickly dissipate by
Thursday. Any convection also likely to remain isolated and
south of the TAF sites again later Wednesday. Next best threat
for showers and storms arrives late Thursday as a new front
approaches from the north with more widespread activity in the
area Friday as the front drifts slowly southeast through the
region.

Saturday looks drier with northwest flow, but could see
lingering low end VFR/high end MVFR ceilings in SE WV.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...JH
NEAR TERM...JH/MBS/RAB
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...JH/RAB/WP