Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus62 kgsp 150828 

Area forecast discussion
National Weather Service Greenville-Spartanburg SC
328 am EST Fri Nov 15 2019

a surface low pressure center will move from the Florida coast to
the coast of of the Carolinas today. The system will linger along
the southeast coastline through Saturday before moving away to the
northeast on Sunday. A couple of weak cold fronts move through the
region Monday and Tuesday. High pressure builds in on Wednesday into


Near term /through tonight/...
as of 325 am: a fairly Stout deformation zone of rain has set up
parallel but south of the I-85 where rainfall rate of around one ten
of an inch per hour has been noted. This band will lift northeast
while gradually weakening through early this morning as the best
upper level support rides the southwest flow aloft towards the mid-
Atlantic states.

An elongated positively tilted trough over the mid-Mississippi
Valley will swing east into the deep south while cutting off and
becoming a closed low at 500 mb. This will support continued surface
low development along the southeast coast and gradual backing of
moisture transport (gulf to Atlantic fetch) through the near term.
The NAM is the most bullish in developing moderate banding of
rainfall with gusty winds near the I-77 corridor late tonight
associated with the easterly flow. Have trended the forecast in this
direction, but by no means is this scenario slam dunk as surface
high pressure to the north will continue to supply drier air at
lower levels, undercutting the fetch of moisture, and possibly
limiting rainfall to the region. Rainfall rates and amounts will be
light north of I-85, especially west of I-77 and moderate with a
quarter to locally half an inch south of I-85 through tonight.
Extensive cloud over and cool northerly flow will support continued
cool conditions, especially for daytime highs as many areas will
struggle to reach 50.


Short term /Saturday through Sunday night/...
as of 155 am friday: a short wave diving into the central Continental U.S.
Saturday and Saturday night will help kick the upper low along the
Georgia/Florida coast slowly eastward. The associated surface low starts the
period along the Carolina coast. The low also moves slowly eastward.
Deformation zone precip may remain over much of the Piedmont
Saturday then taper off Saturday evening as moisture and forcing
move east. While below normal, temps remain warm enough for precip
to remain liquid and ends before temps fall below freezing.

The kicking short wave moves into the area by Sunday night. There is
little in the way of moisture moving in with this wave and only a
weak frontal system. Therefore, have kept the forecast dry for now.
Temps warm but remain below normal.


Long term /Monday through Thursday/...
as of 305 am friday: the kicker short wave moves east of the area
Monday but a secondary short wave rotates through the trough over the
eastern Continental U.S. Tuesday. A short wave ridge moves across the area
Wednesday before another short wave drops into the Great Lakes

At the surface, a weak cold front approaches the area Monday and
crosses the area Tuesday. High pressure moves over on Wednesday
before a cold front approaches on Thursday. There may be enough
moisture with the weak front for some light precip across the area,
but will limit pop to slight chance for now. Dry forecast continues
for Wednesday into Thursday as moisture holds off until Thursday
night ahead of the cold front. Temps will be around 5 degrees below
normal Monday and Tuesday then near normal for Wednesday and


Aviation /09z Friday through Tuesday/...
at kclt and elsewhere: below normal confidence in 06z tafs
especially for along the I-85 corridor including kclt as cigs may
bounce back and fourth between low MVFR and VFR through 15z and
again after 00z. The region will be on the backside of a developing
coastal low, supporting periods of rain and MVFR/IFR cigs. Drier low
level air wrapping behind the system should support generally VFR
cigs/vsbys with limited rain to northern areas including kavl and
khky. There is a 30 percent chance that heavier bands of rain and
gusty winds wrap back into the I-77 corridor including kclt towards
the end of the taf period.

Outlook: precipitation and flight restrictions will likely linger
into the weekend, especially along and southeast of I-85 corridor,
as the aforementioned coastal low drifts up along the coast.

Confidence table...

08-14z 14-20z 20-02z 02-06z
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 97% high 100% high 100% high 100%
kand high 85% high 81% high 91% 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:



Gsp watches/warnings/advisories...



National Weather Service Glossary of Abbreviations