Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 291803

Area Forecast Discussion
National Weather Service Blacksburg VA
203 PM EDT SUN MAY 29 2016

Tropical Storm Bonnie will weaken today as it moves to the South
Carolina coast. This system is expected to move very slowly
northward along the coast the next several days causing unsettled
weather across the mid atlantic region through mid week.


As of Noon EDT Sunday...

Lot`s of cloud cover across the forecast area, but not a lot of
rain. Main focus for rain has been along and east of Highway 29.
Morning RNK sounding indicated a dry layer around 800 any
rain that is falling west of the blue ridge is occurring in an
environment that is not quite saturated...PWAT 1.17. The GSO
sounding on the other hand was near saturation with a PWAT of
1.73. Latest meso analysis continued to indicate dry sub cloud
layer in the west with near saturation south and east of danville.
As such expect the most persistent, and heaviest rain this
afternoon to be mainly confined to our southeastern CWA.

Tropical Depression Bonnie has moved onshore vicinity of
Charleston SC, the heaviest of the rain occurring over south
central South Carolina. Scattered to numerous showers extend
northward from the system into our forecast area.

For our forecast area, unless the showers become more organized
the probability of a flooding sort of rainfall appears low attm.
Latest guidance from WPC continues to focus the heaviest rain and
potential for excessive run-off along the I-95 corridor.

The thunderstorm threat this afternoon appears minimal, clouds and
occasional tropical precip inhibiting instability. That said, will
maintain isolated thunderstorm threat with heavy rain over Southside
Virginia into the NC Piedmont where CAPE will increase from
breaks in the overcast over central/eastern NC.

Tonight, the remnants of Bonnie will stay along or just inland of
the South Carolina coast. Setup continues to favor showers over the
east during the night but usually at night tropical systems with
respect to rainfall tighten up, such that areas along and west of
the Blue Ridge appear to dry out after midnight or have limited
coverage. Still confidence is not high to go completely dry as the
00z NAM and ECMWF are hitting an area over the Triad of NC into
portions of Southside VA around Martinsville and Danville with a
heavy band of rain.

As for temperatures, the clouds and showers should be keeping highs
lower today but expect muggy conditions with temps reaching the 70s
most areas. Tonight stays muggy with lows in the upper 50s mountains
to mid 60s east.


As of 210 am Sunday...

Tropical Storm Bonnie, lingering around the Carolina coast, will be
the focus through mid week. High humidity and showers will be in the
forecast as long as it remains with highest pops along and east of
the Blue Ridge, and lowest in the west. Even if the deeper moisture
hugs the coast, any increase in sunshine across our area will result
in increasing instability with diurnally driven showers and
scattered thunderstorms.

With more breaks in the cloud cover, temperatures will be
warmer than normal with 80s for highs. Lows generally in the 60s.


As of 350 PM EDT Saturday...

The air mass will remain warm and humid, with a continuation of
diurnally driven deep convection. A cold front is forecast to
approach the forecast area from the west Friday. If by chance the
tropical low is still around, this front should give it a boot out
to sea. If there is a threat for stronger sort of storms for this
upcoming week, it would come with Friday`s frontal passage.

Temperatures, especially the overnight lows, will favor above
normal readings through the end of the week.


As of 150 PM EDT Sunday...

High confidence in light winds but below average confidence in
cigs/vsbys during this taf period. The circulation of Bonnie
continues to spin over South Carolina. This is pushing moisture in
our direction from the southeast but we are lacking a good
focusing mechanism to realize significant precipitation.
Orographic affects are being minimized since the low level flow is
not favorable for upslope along most of the Blue Ridge so we are
seeing showers move in our direction and lose a lot of vigor as
they enter the cloudy more stable environment that resides over
the TAF sites. Believe the trend will be for showers to be on the
decrease through early this evening as diurnal heating affects
wane but still expect some showers to be floating around east of
the Ridge through at least early tonight.

Guidance is very keen to develop low cigs and fog at all sites
toward daybreak. Believe there will be too much mid/upper cloud
cover west to allow for good radiational cooling and this should
severely limit the changes for sub VFR conditions at KBLF and
KLWB. The chances for lower cigs and vsbys are better further east
where low level moisture will be higher so will introduce some
MVFR conditions further east. However as stated earlier this is
not a high confidence situation so keep a close eye on
satellite/radar trends and observations.


Low confidence on flight category for Monday-Thursday. Models
indicate low pressure will stall over the eastern mid-atlantic and
linger through mid week. Our forecast area will be on the western
periphery of this feature which suggests best flight conditions
will be over and west of the Blue Ridge. MVFR or lower ceilings
are possible at KLYH and KDAN Monday.




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