Area Forecast Discussion
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FXUS61 KRNK 300548
Area Forecast Discussion
National Weather Service Blacksburg VA
148 AM EDT MON MAY 30 2016
Tropical Depression Bonnie has weakened. It is centered over
eastern South Carolina but will influence our weather over the
next several days as it slowly moves northeast along the coast.
.NEAR TERM /THROUGH TODAY/...
As of 945 PM EDT Sunday...
clouds and scattered showers will remain over the forecast area
through Memorial Day as Tropical Depression Bonnie meanders over
northeast South Carolina.
Abundant cloud cover and tropical moisture extend north through
the Carolinas associated with Tropical Depression Bonnie. This
tropical system is forecast to move very little through Monday,
resulting in considerable cloudiness throughout the Mid Atlantic
Region along with scattered to numerous showers and thunderstorms.
PWATs east of the Blue Ridge are in excess of 1.50 inches, thus
any deep convection will be rain efficient, heavy downpours
potentially leading to poor drainage flooding. Coverage and
rainfall amounts through 8PM have not justified the need for a
flood watch. Highest amounts were from the north side of Roanoke
city into southern Botetourt County with 0.75 to 1.0 inches
Sunday. Have trimmed back the probability of rain overnight. Hi-
Res models as well as HRRR forecast only isolated to scattered
coverage and radar trends are supporting this decrease.
Western edge of deep moisture had advanced into extreme southwest
Virginia and will stay close to the western border of the
forecast area overnight. Have slightly lowered minimum
temperatures to reflect 9PM observations and latest LAV guidance.
For Monday and Monday night the circulation center is expected to
move very little...the Tropical Prediction Center showing a slight
jog to the north. Unlike today were there was abundant mid/upper
level moisture, models on Monday are suggesting some drying in the
mid levels allowing for some breaks in the overcast and subjecting
the forecast area to surface heating. This increase in solar
insolation is expected to increase the CAPE, allowing for
diurnally driven deep convection. Since airmass is of tropical
origin, anything that develops will contain heavy downpours.
Temperatures through Memorial Day will remain mild, elevated
dewpoints keeping the overnight lows above normal. The daytime
high is advertised in the 70s, but could easily eclipse 80 with a
few hours of sun.
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
As of 400 PM EDT Sunday...
Little change through mid week. TD Bonnie is forecast to slowly
move northeast just inland of the coast. Heaviest rain is forecast
to be aligned with the I-95 corridor, however our forecast area
will be subject to a daily threat of diurnally driven deep
convection aligned with the mountain ridges. Steering currents are
forecast to be weak, and with PWATs running AOA 1.5 inches,
expect scattered slow moving showers/storms with heavy downpours.
With more breaks in the cloud cover, temperatures will be warmer
than normal with 80s for highs. Lows generally in the 60s.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 400 PM EDT Sunday...
Thursday 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 late Thursday
into Friday. This boundary 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
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
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
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.