Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Greenville-Spartanburg SC
634 am EDT Sat may 23 2015
dry Canadian high pressure will linger atop the region through the
Holiday weekend. A southerly flow of moisture around Bermuda high
pressure will gradually return next week.
Near term /through tonight/...
as of 630 am...forecast is on track...so no changes needed with this
As of 230 am...an upper ridge will continue to build along a
negatively-tilted axis from Florida to to Minnesota. The height rises atop the
County warning forecast area will help keep things dry with sunny to mostly sunny skies. The
center of surface high pressure will shift from the central Appalachians
this morning...to just off the middle Atlantic coast tonight. So with
flow turning out of the southeast...temperatures will be a category or two
warmer today than yesterday...still about a category below normal
for most locations. Lows tonight under mostly clear skies will be
Short term /Sunday through Monday night/...
as of 150 am Saturday...dry weather will continue on Sunday as upper ridge
axis continues to build atop the southeast Continental U.S.. low level flow around Bermuda
hipres will steadily advect higher temperatures and dewpoints into the
southern Appalachians. Temperatures will be a few degrees warmer than
Saturday topping out a few degrees above normal. The upper pattern
evolves slowly on Monday with the ridge axis sharpening and moving
east closer to the coast. This combined with a steady increase in
low level moisture due to the increasing southerly flow around the
weakening ridge axis of the surface Bermuda high will create increasing
instability and chance of mainly diurnal convection. Best chance will be
across the NC mountains...NE Georgia and upstate west of I-26...with little to
no chance over the I-77 corridor where the suppressive effects of the
ridge continue. Highs Monday remain nearly steady west and rise a
couple of degrees east.
Long term /Tuesday through Friday/...
as of 255 am Sat...the medium range continues to look Summer-like
with an upper ridge axis along the Atlantic coast and a surface Bermuda
high across the southeast keeping a generally moist flow from the Gulf and
Atlantic at low levels across the County warning forecast area. This will favor above normal
temperatures and mainly diurnal showers and storms each day. The GFS
continues to forecast the ridge breaking down late in the period
allowing short wave energy and a weak cold front to move into the
area. The European model (ecmwf) continues to forecast the upper ridge/Bermuda high
pattern right through the forecast period. Given the discrepancy...have
trended toward the more steady European model (ecmwf) forecast. Convective coverage will
be higher across the mountains and western County warning forecast area each day where better
moisture and instability remain farther from the upper ridge axis.
The chances for severe thunderstorms each day look minimal at this
point because of poor lapse rates and relatively weak instability
with middle level warm air.
Aviation /12z Saturday through Wednesday/...
at kclt and elsewhere...no major changes for the 12z tafs. The
center of dry high pressure will shift from the Appalachians to the
East Coast today...keeping dry air in place...but shifting the winds
from NE to southeast by this afternoon. Winds should remain light...picking up to
around 5-7 knots this afternoon. Other than a few periods of cirrus...not
expecting any other clouds or fog at any of the taf sites through
Outlook...high pressure will shift east off the East Coast early
next week...allowing moisture to gradually return out of the south.
Conditions should remain generally fair through the period.
10-16z 16-22z 22-04z 04-06z
kclt high 100% high 100% high 100% high 100%
kgsp high 100% high 100% high 100% high 100%
kavl high 100% high 100% high 100% high 100%
khky high 100% high 100% high 100% high 100%
kgmu high 100% high 100% high 100% high 100%
kand high 100% high 100% high 100% high 100%
The percentage reflects the number of guidance members agreeing
with the scheduled taf issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link: (must be lower case)