Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 242343

Area Forecast Discussion
National Weather Service Blacksburg VA
743 PM EDT Tue Apr 24 2018

An area of low pressure will head offshore tonight, but the Mid
Atlantic will remain cool and damp. As this area of low
pressure departs on Wednesday, an additional disturbance could
bring more rain during Thursday and Friday. High pressure should
arrive to provide drier conditions by the upcoming weekend.


As of 300 PM EDT Tuesday...

A closed upper level trough continues to pivot toward North
Carolina this afternoon. The bulk of the steady rain spinning
around this trough has progressed toward eastern Virginia and
left most of our area just cloudy at this time. Meanwhile, east
winds continue to keep us wedged with cool and damp air.
Rainfall amounts varied considerably with this event from less
than a half an inch to over four inches as shown in our earlier
public information statement. Minor flooding of roads was
reported in Watauga County, but creeks and streams across the
entire southern Blue Ridge are currently receding. Thus, the
Flood Watch will be allowed to expire at 4 PM today.

While there will be additional chances of rain this evening and
tonight, it should become more spotty in coverage. Locations
west of a line from Boone to Lewisburg could see showers
lingering all night as winds shift to the northwest. Elsewhere,
rain may arrive from convection forming over South Carolina at
this hour that will head toward the North Carolina Piedmont and
Southside Virginia by early tonight. The stable boundary layer
should inhibit any chance of thunder as this activity weakens.
Expect low clouds and plenty of fog by Wednesday morning due to
lighter winds and plentiful surface moisture, and it may take
most of the morning to see much improvement. By the afternoon,
some clearing should take place. Therefore, a non-diurnal
temperature curve was utilized with a slow warm up early
followed by a late surge toward sunset.


As of 245 PM EDT Tuesday...

During this portion of the forecast, the region will remain
within a progressive pattern of shortwave troughs rounding the
base of a longer wave trough through our region. Each of these
will bring the chance of showers for about a 12 to 18 hour
period as they zip through the area.

The first of these is slated for Thursday night into early Friday,
with the second on its heels late friday into Friday night. While
there is fairly good agreement in the models regarding the placement
and timing of the first system, there is much more uncertainty as to
the impacts for our region regarding the second of these two

As such, confidence in showers impacting the area Thursday night
into Friday is larger than that of the second system. In fact, the
difference is such that likely POPs are forecast much of the area
for the first system, with the second, at this point, only
associated with a continuation of at least a mostly cloudy sky and
no or very little precipitation to mention.

Temperatures during this portion of the forecast will average very
close to normal for this time of the year.


As of 1205 PM EDT Tuesday...

During this portion of the forecast, we expect a transition
from a pattern of a peristent trough across the eastern U.S. to
one of an a building ridge. The result will be a primarily dry
forecast and a trend towards higher temperatures. The one small
chance for precipitation will be isolated showers on Saturday in
the eastern part of the forecast, nearest the axis of the
departing upper trough.

The time period will start with high temperatures on Saturday
ranging from the low to mid 60s across the mountains to the lower
70s across the Piedmont. By Tuesday, highs are forecast to range
from the lower to mid 70s across the mountains to the upper 70s to
around 80 degrees for the Piedmont region.

Low temperatures for the weekend will average the upper 30s to lower
40s across the mountains and low to mid 40s across the Piedmont. By
Tuesday morning, lows will range from the mid to upper 40s across
the mountains to the upper 40s to around 50 across the Piedmont.


As of 736 PM EDT Tuesday...

The combination of high pressure wedged down east of the
mountains and a vertically stacked low sliding across the region
will keep generally IFR conditions across the region into
Wednesday with a good chance of rain at TAF sites. Also expect
some fog development overnight given some cooling and abundant
low level moisture. As the upper trof starts to pull away later
on Wednesday conditions will improve to VFR east of the Blue
Ridge but expect MVFR/IFR to linger from the Ridge westward due
to wind shifting to an upslope northwesterly direction. However,
some breaks of sun in the east may create enough instability to
get some thunder going so will mention VCTS at KLYH and KDAN
toward the end of the period.

Extended Aviation Discussion...

Unsettled weather conditions should continue for the remainder
of this work week as another area of low pressure heads toward
the Mid Atlantic. MVFR/IFR ceilings along with rain showers may
take place during Thursday night and Friday. High pressure
should build overhead to bring VFR conditions for all sites by
Saturday afternoon. Good flying weather will persist through
the remainder of this weekend.




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