Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 301453

Area Forecast Discussion
National Weather Service Blacksburg VA
1053 AM EDT Sat Jul 30 2016

Low pressure will drift east through the Ohio Valley today and
Sunday with a weak front trailing east to the Mid Atlantic coast
and west into the Central Plains. Monday into Wednesday the low
will be offshore with the front extending into the Carolinas.


As of 1030 AM EDT Saturday...

Very little change in the forecast, though lowered pops this
morning based on radar/high-res model trends. Models still are
favoring two distinct areas of convection this afternoon, one over
the WV mountains into portions of Southwest VA, and the other
across the piedmont north of Danville, especially in the Amherst
to Appomattox corridor. Main shortwave energy is expected to shift
from Indiana/Kentucky this morning into northern Wv by late this
afternoon. Increase in westerlies with some backing will be key on
severe potential. MLCAPEs around 1000-1500 J/kg expected in the
east. Cloud cover in the west appears to be limiting severe threat
with sunshine prevalent across the Blue Ridge north of Floyd this
morning. No other major changes to the forecast wit this update.

Previous valid discussion...

Maximum temperatures today will be similar to Friday. Lows
tonight will remain mild. Stayed close to MAV guidance for both


As of 300 AM EDT Saturday...

An upper level trough centered over the Great Lakes Saturday night
will track east to Lake Erie on Monday. Bulk of the dynamics and
energy will remain to our north over Ohio-Pennsylvania-New York
through the period. A prefrontal short waves will bring a chance for
showers and thunderstorms to the region Sunday afternoon and
evening. A cold front will bring another round of thunderstorms to
the area on Monday. Overall chances for strong to severe storms are
low each day as deep westerly flow persist each morning. Low level
winds back during the afternoon across the piedmont, however
westerly flow will have reduced pwats and instabilities to limit
severe activity. Model pwats Sunday are around 1.60 inches and near
normal (1.40 inches) on Monday.

Temperatures will run near normal both days with 80s west to lower
90s east. A noticable drop in dewpoints will be felt, dropping from a
week long run in the upper 60s to lower 70s down into the lower to
mid 60s.


As of 300 PM EST Friday...

Extended range models (GFS/Euro) show upper trough over the
northeast slowly lifting out on Tuesday with surface high pressure
in control and generally dry conditions. Significant exception is
12z Canadian model which brings a strong short-wave across the
central Appalachians late Monday into Tuesday with high chances
for rainfall. Elected to discount that solution for now and go
mostly dry on Tuesday with slightly lower humidity, could even see
a few dewpoints under 60F in the western mountains and under 70F
east, which may actually be noticeable. Temps generally seasonable
for early August. Front drifts back toward the north on Wednesday
with increasing pops and and humidity as heights begin to build
aloft once again. With upper ridge and rising heights continuing
to shift eastward Thursday and Friday should see warmer temps and
higher humidities again with renewed pattern of scattered
afternoon storms but nothing particularly organized.


As of 745 AM EDT Saturday...

Scattered showers and isolated thunderstorms were moving northeast
across northern North Carolina and southwest Virginia this
morning. MSAS analysis still showed some weak instability and
CAPES around 500 J/KG in this area. With a short wave supporting
this precipitation, expect the showers and thunderstorms to
continue to move across KLYH and KDAN but WILL be east of KLYH and
KDAN after 13Z/9AM. IFR to LIFR Stratus and fog over the mountains
will dissipate by 14Z/10AM.

Another vorticity maximum tracking out of the Ohio Valley will
cross West Virginia and Virginia today and will trigger showers
and thunderstorms this afternoon and evening. Only medium
confidence on the times these storms may impact local airports.
Strong gusty winds are possible with the more intense thunderstorms
this afternoon.

Extended aviation discussion...

The region will remain in an active weather pattern into early
next week. A nearly stationary frontal boundary will be across or
near the region, all while a series of upper level disturbances
moves along this feature through the area. By Wednesday the front
may move south of the region enough to take the focus for
additional showers and storms with it. VFR conditions are expected
for most of the time. The exception will be temporary sub-VFR
conditions under the heavier showers or thunderstorms, and during
the night with patchy light fog and stratus cloud development over
parts of the region.




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