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Area Forecast Discussion

FXUS62 KGSP 261046

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
646 AM EDT SUN JUN 26 2016

A weak cold front stalled out south of the region will wash out
today as drier air continues to move in from the northeast.
Another cold front will sweep in Monday night, nearly stalling out
early on Tuesday leading to continued precipitation chances.  High
pressure should build in from the north for the middle part of next
week leading to a brief period of drying.  Diurnal precipitation
chances will resume through late week.


At 645 AM EDT, low clouds across the area will slowly scatter out
and lift through the morning with mostly sunny skies expected by
early afternoon. The low level flow turns more southeasterly this
afternoon keeping low level moisture, and the resulting instability,
across the mountains and Upper Savannah River Valley. The NAM once
again shows very high instability across the area, but the GFS and
SREF are more reasonable. The result will be scattered diurnal
convection across this area with a dry forecast elsewhere. Thickness
values will be lower across the western CWFA today with similar
values across the east. This will put highs right around normal.

Convection should dissipate this evening with the loss of heating.
The low level flow turns more southerly overnight which may bring a
return of low clouds across the western CWFA. Lows will be a few
degrees above normal.


As of 300 AM EDT Sunday:  The short term fcst period kicks
off Monday morning as a broad H5 ridge dominates across the
central/southern CONUS, while a trof digs south out of central
Canada into the Great Lakes region.  Meanwhile at the sfc, the
prevailing east coast ridge will be retreating to the northeast
allowing for the return of weak southerly waa across the southeast
states ahead of a cold front diving southward beneath the a fore
mentioned H5 trof.

Guidance continues to converge on a prefrontal trof pushing into the
southern Appalachians Monday afternoon/evening, likely accompanied
by an MCS.  This MCS/trof is progged to move into the NC high
terrain by mid/late afternoon, before propagating southeast into
the northeast GA and the NC/SC foothills/piedmont into the the
evening hours.  Upper flow remains relatively weak as the H3/H5
jet maxes reside well to the north across the Great Lakes, thus
providing little/no synoptic scale lift to enhance convection.
Profiles do exhibit modest CAPE ahead of the front/trof in the
building warm sector, generally 1-2k j/kg, all the while displaying
elevated LCL`s that would favor enhanced DCAPE and thus an increased
downburst threat.  Convection looks to die down a bit after heating
in lost into Monday night, however wouldn`t be suprised to see
continued shower activity through early morning given persistence
of elevated CAPE and moistening profiles.

The cold front finally looks to move into the picture on Tuesday
as a sprawling surface ridge spills into the OH valley, while the
old sfc trof looks to wash out over the Midlands.  Profiles are
increasingly moist on Tuesday thus think sky cover will work to keep
temperatures lower and thus yielding less instability.  The front
is progged move into the western NC by early evening,  eventually
spreading across the remainder of the fcst area overnight, likely
with little fanfare given the limited buoyancy.

All said, pops will maximize in the likely range across much of
western NC on Monday, topping out in the high chance range further
south into northeast GA and the SC upstate.  Pops will remain in the
mid/high chance range on Tuesday with the highest pops along/south
of I85 in proximity to the old quasi stationary sfc trof and any
residual boundaries.  Temperatures on Monday will top out near
normal, before falling a few degree below normal for Tuesday.


As of 330 AM EDT Sunday:  The medium range fcst period initializes
on Wednesday morning amidst a broad H5 ridge centered over the
desert southwest while a large trof encompasses the eastern CONUS.
At the surface, high pressure looks to build across the OH/TN
valleys, eastward into the southern Appalachians, while an
old frontal axis remains draped across the deep south possibly
providing focus for wave development.  Guidance suggests that the
surface ridge will move by just to the north, thus allowing for
weaker surface based inhibition along south of the I40 corridor
Wednesday and Thursday, before moving northeast on Friday.
During this time, diurnally favored convection looks probable,
however coverage limitations will keep pops below climo levels.
Late in the period another cold front is fcst to push across the
MO valley, eventually moving into the OH valley region Saturday
evening.  Diurnal convective trends will continue Saturday ahead
of the front into Sunday where precipitation chances looks to
improve further.  Temperatures through the period will gradually
moderate back to normal levels.


At KCLT, MVFR cigs will scatter out by late morning with the
scattered cumulus slowly lifting to higher based VFR by early
afternoon. These clouds will linger through the night with
increasing amounts of cirrus. ENE wind today becomes ESE this
evening, then light S overnight.

Elsewhere, similar conditions to KCLT, but with slightly different
timing. KAND has the least chance of seeing MVFR cigs, but they will
be close by. KAVL will have S winds through the period. Scattered
convection could flirt with KAVL and isolated convection with KAND
later in the afternoon. However, chance too low to include in the
TAF for now.

Outlook: Better shower and thunderstorm coverage is expected on
Monday as a cold front approaches from the NW. Scattered convection
could linger into Tue. Diurnal TSTM chances will build again on
Thursday afternoon. Restrictions should be confined to
thunderstorms, fog in the wake of heavy rainfall, and river valley
stratus each morning.

Confidence Table...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       Med   70%     High 100%     High 100%     High 100%
KGSP       Med   65%     High 100%     High 100%     High 100%
KAVL       Med   73%     High  92%     High 100%     High  91%
KHKY       Low   55%     High 100%     High 100%     High 100%
KGMU       Med   65%     High 100%     High 100%     High 100%
KAND       Med   67%     Med   77%     High 100%     High 100%

The percentage reflects the number of guidance members agreeing
with the schedule TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:






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