Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 300757

Area Forecast Discussion
National Weather Service Blacksburg VA
357 AM EDT MON MAY 30 2016

Tropical depression Bonnie will stay near the South Carolina coast
today into tonight, slowly working northeast to the North Carolina
coast Tuesday. A cold front arriving from the west Friday will
finally boot Bonnie out to sea.


As of 330 AM EDT Monday...

Tropical depression Bonnie continues to track very slowly if at all
between Charleston and Myrtle Beach. Water vapor satellite shows a
plume of tropical moisture feeding into the NC coast then northward
across the Virginia piedmont. Drier air is situated across the
Appalachians with more moisture with a shortwave moving across the
Ohio Valley. Early this morning a narrow band of showers had formed
near I-77 in NC north along the Blue Ridge of Virginia. The 04z HRRR
seemed to be picking up on this fairly well with subsequent 06z run
also hitting the southern Blue Ridge into the NC foothills with best
threat of showers this morning with isolated to scattered coverage
to the east. At the same time fog was becoming dense where it had
cleared along and west of the Blue Ridge from Fancy Gap north toward
I-81 from Marion to Christiansburg. Think fog will be periodic based
on in and out lower clouds and possible showers but enough coverage
of lower visibilities to warrant a Special Wx Statement.

For today, any fog will be diminishing by 9am. Following the HRRR
into late morning and blending with the 00z GFS as it seemed to have
a decent handle on synoptic features gives us isolate to scattered
showers til lunchtime. Should see some sunshine enough to destablize
the airmass. More thunder is expected this afternoon, but not
expecting it to be widespread, as it will be dependent on how much
sunshine occurs. This afternoon, thinking the better low level
convergence stays near the Blue Ridge and the across the Piedmont
roughly east of a LYH-DAN line and moreso east of our forecast area.
Looking for high chance to even low likely pops along and either
side of the Blue Ridge this afternoon and then east of South Boston
to Charlotte Court House with low/scattered threat elsewhere. Given
the flow from the sfc-7h mb will be mainly light from the NNE should
see some heavy rain potential with slow moving storms and
precipitable water values of 1.5". At the moment will not highlight
this in the HWO as it will be isolated, but would not be surprised
that a flood advisory or even a flash flood warning is issued later
this afternoon for small scale area.

With a little more sunshine or breaks expected went close to MAV
guidance on highs with mainly upper 70s to lower 80s across a good
deal of the region. Slightly cooler in the lower to mid 70s along
the Southern Blue Ridge.

Tonight, remnants of Bonnie still situated near the NC/SC coast.
Models show deeper moisture well east of us but will still be in a
tropical like airmass and think showers will linger all night, though
coverage will lessen as will thunderstorm threat. Will go with
isolated coverage most of the night and still looks like areas near
the Blue Ridge may stay in more of a favorable low level convergence
zone to keep isolated showers here through the overnight. Drier air
will try to make it at least to the WV/VA border south toward the
NC/TN border. This gradient will likely enhance fog potential with
fog likely most areas overnight.


As of 210 AM EDT Monday...

Tropical Depression Bonnie will continue to linger over the
Carolinas through Thursday. While Bonnie is inland, she will
continue to weaken, losing her closed circulation aloft. However,
she will maintain and generate spiral bands of convection,
especially during the afternoon, fading in the evening. These bands
will likely move east over the piedmont, possibly making it to the
Blue Ridge each afternoon. Even if these bands do not track that far
east, afternoon heating and easterly upslope in a tropical air mass
should be enough to generate scattered showers and an isolated
thunderstorm along and west of the Blue Ridge Tuesday and Wednesday
afternoon. By Thursday, a closed low is expected to move over the
Great Lakes and its associated cold front will enter the Ohio
Valley. This front will give Bonnie a nudge out to sea. This cold
front and remaining tropical moisture will bring a good chance for
widespread showers Thursday and Thursday night.

Temperatures will continue to warm by a degree or two each day until
the front moves east of the area Thursday night into Friday.
Temperatures will generally warm into the upper 70s to lower 80s.
Overnight lows will remain muggy and in the 60s.


As of 400 PM EDT Sunday...

A cold front Friday will result in an increased threat for
showers/storms...its passage bringing a less humid airmass to the
region for the weekend.

Until the frontal passage at the end of the week, temperatures,
especially the overnight lows, will favor above normal readings.
After the frontal passage, lower dewpoints and clearing skies will
support lower nightime lows. Daytime highs are advertised to be close
to normal.


As of 137 AM EDT Monday...

Terminals will be tricky this morning as skies had cleared enough
to allow fog to form and start to form. Any fog is contingent on
how much low and mid deck forms and/or moves in. Have high enough
confidence in the LWB/BCB terminals to put MVFR fog with tempo IFR
to LIFR vsbys and/or cigs. Liked the overall solution of the GFS
and 4z HRRR which paints some light showers near DAN this morning
then develops some toward BCB/BLF after 08-10z.

Further east there should be some breaks as well and with rainfall
earlier fog will be a fair bet at LYH/DAN, and possibly ROA.
Overall keeping them MVFR fog with possible IFR cigs.

Expect some slow deterioration to any lower cigs this morning and
will see a few showers around. As we head toward late morning into
early afternoon look for more of a broken deck of cu/sc rising to
high end MVFR then VFR. Nothing to focus where shra/storms form
but looking at shotgun effect with all terminals possibly having
at least a shower or tsra in the vicinity during the afternoon, so
kept that in from previous taf issuance, but delayed based on the
fact the heating will be delayed with low clouds to start the

Any showers will dissipate somewhat enough to take VCTS out of
the Tafs by 00z/31. Fog will be possible moreso after the end of
this taf cycle.


There may be a repeat of tonight again Monday night into Tuesday
morning. What remains of Bonnie appears to stay situated over the
SC coast with our area staying just close enough to keep a few
showers around at night then scattered storms during the afternoon
again Tuesday. This looks to possibly play out again Tuesday night
into Wednesday.

Finally an stronger upper trough will kick what is left of Bonnie
out to sea Thursday-Friday. Thursday may be our driest day with
frontal showers and storms Thu night into Friday. Overall looking
at possible MVFR to IFR at night through Thursday morning, with
mainly VFR during the day except in showers/storms.




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