Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
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FXUS61 KRNK 290156
Area Forecast Discussion
National Weather Service Blacksburg VA
956 PM EDT SAT MAY 28 2016
An area of low pressure is centered near the coast of South
Carolina. This system is forecast to move very slowly northward
along the coast the next several days causing unsettled weather
across the mid atlantic region through mid week.
.NEAR TERM /THROUGH SUNDAY NIGHT/...
-- Changed Discussion --As of 950 PM EDT Saturday...
Forecast models are in general agreement, tropical low pressure
near the south carolina coast resulting in increasing cloudiness
across the carolinas overnight and a northwest drift of showers
from the coast...reaching the VA/NC border by daybreak Sunday.
Have slowed down the arrival time of the precipitation in the
southern county warning area until between 06Z/2AM and 09Z/5AM
based on several of the latest short range models.
Differences in the models arise Sunday and Sunday night as to how
far west there will be precip and how fast the precip exits, or
not exits the area Sunday night. This will also have ramifications
to the QPF.
Attm will heavily weight forecast to the Weather Prediction Center
(WPC) guidance in lieu of consistency and need to see if/when
tropical system gets its act together with respect to
strengthening or not strengthening with time and eventual track.
That said, forecast is for showers moving into the southern CWA
vicinity of the VA/NC border by daybreak Sunday, then spreading
NNW into VA during the morning. Not confident of much precip
making it into WVA or far western Va so will maintain a tight
gradient of POPs west of the Blue Ridge...with chance in the
western CWA and near categorical east.
The airmass is of tropical origin, so dewpoints will remain high
thus supporting mild temperatures. In spite of cloud cover, highs
will still be in the 70s and lows in the 60s.
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.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 340 PM EDT Saturday...
Tropical low lingering near the mid-Atlantic 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
scattered showers and thunderstorms over the mountains.
With more breaks in the cloud cover, temperatures should be warmer
with 80s for highs. Lows generally in the 60s.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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.
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
As of 750 PM EDT Saturday...
High clouds will continue to spread north across the region
tonight. Ceilings will lower gradually late tonight and Sunday
morning. The mid/high clouds should prevent fog development at KBCB and
KLWB Sunday morning. High confidence that ceilings will remain
VFR through at least 15Z/11AM. Have slowed down arrival of rain
that is associated with Tropical Storm Bonnie. Medium to high
confidence on this timing with KDAN into the rain around 12Z and
KLWB not getting the rain until after 21Z. Soundings still have a
deep layer of dry air but guidance has been consistent bringing up
high precipitable water values and shifting the area of subsidence
north and west of the forecast area.
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.