Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 290750

Area Forecast Discussion
National Weather Service Blacksburg VA
350 AM 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 330 AM EDT Sunday...

Early this morning, the center of Tropical Storm Bonnie was located
off the South Carolina coast. This system has been slow to move.
However, showers have made it as far northwest as I-40 in NC, but
even that is light coming from a mid deck. The 00z GFS seemed too
fast with rainfall this morning, and overall followed the 00z Local
WRF/NAM and ECMWF solutions.

With these solutions still sharp gradient between where the heavier
showers fall today into this evening and where it hardly rains at
all. Cut back on pops today with still some likely to categorical
pops in the Piedmont and to the Blue Ridge. Subsidence zone may
allow for some drying in the north today with models allowing for
possible scattered showers to move over the WV/Far SW VA mountains
this afternoon. At this time will see higher PWATS of 1.5" or higher
edge into the Piedmont with an inch over the mountains. Given fairly
different solutions in terms of where heavier rains will fall, the
overall setup does not show a high probability for flooding rains.
Will still have to watch for any slower movement later today. For
may add possible localized flooding in the Hazardous Weather Outlook
in the Piedmont, with low probability elsewhere.

As far as thunderstorms go, seems enough cloud cover and low topped
showers given tropical setup to limit thunder. Will keep isolated
thunderstorms with heavy rain over the Southside Virginia into NC
piedmont area.

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 139 AM EDT Sunday...

Problem for aviation will be remnants of tropical storm Bonnie
along the SC/NC today into tonight. Not a lot of consistency in
model solutions on how west and north the rain and in turn the
lower cigs make it this period. Based on latest guidance will lean
toward the local 00z WRF combined with a blend of the 00z nam/gfs.
With this in mind will see a delay in rainfall and lower cigs. At
this time seems Roanoke and points east will have better threat of
seeing rainfall causing cigs/vsbys to drop to mvfr or worse at
times in the 18-end of taf period time though look for
improvements at Roanoke after 03z/30. Further west will see some
rain make it to BCB/LWB but not confident will see cigs/vsbys
below 3kft.

Before that already seeing a dewpoint depression of 2f at LWB and
with slow down of cloudier skies, models show potential for mvfr
fog after 09z at LWB so added a tempo group.


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 Sunday night and Monday.




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