Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRNK 310537
Area Forecast Discussion
National Weather Service Blacksburg VA
137 AM EDT TUE MAY 31 2016
The remnants of Bonnie will linger along the South Carolina coast
tonight, before slowly working northeast to the North Carolina
coast Tuesday. A cold front arriving from the west Thursday into Friday
will finally boot Bonnie out to sea by the end of the week.
.NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --As of 114 am EDT Tuesday...
Updated forecast reflects radar trends which closely resemble a
mix of the 04z HRRR and the 00z Local WRF. Still seeing some
instability gradient per mesoanalysis along/east of the Blue
Ridge. Will see showers mainly isolated linger here for most of
the early morning. Added more fog to the grids, but will be
contingent on clearing. Best bet over the New River Valley and
near the Blue Ridge.
Previous valid discussion...
Expecting another mild overnight given moist dewpoints with lows
mainly 60 to 65 except for a few cooler 50s mountains.
Faint boundary should shift east of the mountains Tuesday as the
remnant tropical low remains stuck near ILM/MYR through the
afternoon. Models again attempt to swing a band or two of deeper
moisture into far eastern sections while keeping a low level
convergence zone out west. This would again support more scattered
nature deeper convection mountains as forecast CAPE values climb
to above 1k J/KG despite only weak forcing aloft. However pwats
remain quite moist so expecting more heavy rain potential as the
continued low level north/ne trajectory under sw flow aloft will
likely keep showers from moving too much. This more in line with
the latest drier 12z ECMWF, so running again with mainly chance
pops, although spots along and just east of the Blue Ridge may
stay dry per lingering subsidence once fog/low clouds burn off.
Kept highs closer to the warmer mos after a mild start with most
in the 80-85 range.
-- End Changed Discussion --
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
As of 230 PM EDT Monday...
Continued sluggish pattern will result in a repeat performance
Tuesday night of that seen tonight with early convection likely
giving way to fog and only isolated pops per latest drier Nam.
Flow over the west should finally start to turn more southerly
later Wednesday afternoon as the Bonnie remnant slides toward the
Outer Banks by Wednesday night and a weak backdoor front slips
toward the region from the north. Guidance also suggests that weak
shortwave energy may eject across the mountains from the west
later in the day with tropical moisture and instability still in
place. This may allow for a bit more widespread scattering of
convection Wednesday afternoon but still not overly impressed.
Therefore bumped up pops a little but still moreso on the side of
the drier Nam/Euro solutions at this point with still some weak
subsidence in place. Again expect any evening convection to fade
by midnight Wednesday night with added fog around overnight.
Upper heights should start to decrease on Thursday with developing
upper troffiness heading southeast toward the region preceded by a
weak surface cold front in the afternoon. This will allow for a
very congested scenario with the Bonnie remnant near HSE, weak
subsidence over the Piedmont, and a pre-frontal convergence zone
working into deep pwats over the west where aided by orographics
and decent instability. However just how far east lift across the
west gets remains uncertain given latest slower trends, but
perhaps enough to include afternoon likely pops far western
sections and higher chances out to the Blue Ridge.
Temps again of the warm/humid flavor with lows mostly 60s and
highs in the low/mid 80s.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 1245 PM EDT Monday...
Gradual lowering of heights will continue into next weekend as
the upper zonal flow starts to break down and eventually gives way
to a more pronounced trough across the region into early next
week. This should be preceded by passing surface cold fronts with
the initial boundary approaching Thursday night and crossing the
area Friday pending timing of a few differing model solutions.
This looks to put the best coverage of convection over the
mountains Thursday evening and then perhaps southern/eastern
sections Friday. However appears decent chances to likely pops in
order across the CWA per a typical slower scenario than guidance
suggests given the lagging mean upper trough well to the
northwest. Initial boundary should be to the south Saturday with a
brief lull in showers possible before the true secondary front
arrives Sunday. This boundary ahead of a rather potent chilly
upper cold pool for early June that will pivot east across the
region by Day7 and likely knock temps back to below normal levels
for early next week. Ahead of the front looks like added bands of
shra/tsra Sunday followed by more post frontal upslope nature
western showers Monday. Otherwise warm and humid temps with highs
at or above normal to prevail into Saturday despite some drying
early in the weekend. This before seeing somewhat cooler and even
drier air especially mountains by Monday as deeper cool advection
arrives with highs mostly in the 70s west to around 80 east.
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --As of 130 AM EDT Tuesday...
Fog will be good bet across LWB/BCB with clearing, but not sure
how low it will go elsewhere. Dealing with more clouds east of
Roanoke and Bluefield seems to have a larger dewpoint spread.
Still could see some tempo periods of IFR fog at all sites, with
LWB/BCB falling to LIFR after 09z.
Confidence on having even VCTS in the tafs is low. Axis seems to
setup across the Blue Ridge or just east Tuesday afternoon. At the
moment took out VCTS or VCSH from the forecast except BCB. This
can be amended later today once we see where convection forms.
Otherwise look fog/low clouds to start to lift out to VFR
conditions after 12-14z.
Mainly VFR with scattered to broken cu field with some AC/CS
aloft, with less cloud cover as you head toward BLF.
Any convection should still hang on into the evening, but again
lack of coverage is such that not needed in the terminals at this
Similar setup again Tuesday night with more fog around after any
evening convection ends. Appears convection may be more isolated
Wednesday as the area slides in between the next upstream cold
front and the remnants of Bonnie near the coast. Thus more
potential to see more widespread VFR Wednesday with exceptions
over the east and with any pop up storms across the mountains.
Finally an stronger upper trough will kick what is left of Bonnie
out to sea Thursday-Friday. Expect more widespread showers Thursday
afternoon into Friday ahead of a cold front, making for periods
of sub-VFR ceilings and visibilities. Saturday may be VFR behind
this front and before moisture and lowering conditions return by
-- End Changed Discussion --