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fxus62 kgsp 132354 

Area forecast discussion
National Weather Service Greenville-Spartanburg SC
654 PM EST Wed Nov 13 2019

a cold air mass will linger over the region through the end of the
week. Meanwhile, a coastal low pressure system will track from the
northern Gulf to the coastal waters of the Carolinas. This will
increase rain chances for the end of the work week, especially for
the eastern half of the forecast area.


Near term /through Thursday/...
as of 630 pm: main update for the 00z taf issuance along with
minor adjustments made to temperatures to coincide with latest
trends, as the rest of the near term forecast remains on track.
Conditions remain quiet this evening with current temperatures
are in the upper 30s to low 40s.

Previous discussion: with cloud cover beginning to increase
overnight, low temps overnight/early tomorrow should be a few
degrees warmer than this morning, but still well-below normal for

Otherwise, the upper-lvl pattern flattens out this evening as the
trof axis lifts farther northeast. As we go into Thursday, another
upper trof digs down across the Central Plains as a closed 500 mb low
moves eastward across northern Mexico and southern Texas. As it does,
it will open up and phase with the above mentioned upper trof. By
the end of the period late Thursday, the trof axis is still to our
northwest with upper lvl flow from the SW. At the sfc, a 1030+ mb high will
slide eastward and then NE later tonight and tomorrow, moving off
the New England coast by late Thursday. As the high moves farther
away from our fcst area, deeper-lyr moisture from the Gulf will
spread into the fcst area from the SW. By late tomorrow morning,
most of the County warning forecast area will likely be seeing bkn to ovc cloud cover with
precip chances gradually increasing thru the day. By tomorrow night,
most of the County warning forecast area has solid chance pops, with likely pops starting
to creep into the southern-most zones. Thru late Thursday, any quantitative precipitation forecast
should be minimal. High temps tomorrow will remain well-below normal,
especially across the lower terrain, where cloud cover should steadily
increase thru the morning. The higher terrain should see less cloud
cover during the morning and early afternoon, and as a result will
likely see warmer temps tomorrow afternoon.


Short term /Thursday night through Friday night/...
as of 200 PM wednesday: the 12z models have definitely come in
wetter for Thursday night thru Friday, especially across the
southeastern half of the forecast area. A vigorous shortwave dive
into the southeast and close off into a compact upper low invof Alabama
by 00z Saturday. The approaching low will bring deep-layer q-vector
convergence over the region, inducing cyclogenesis near the Florida
Panhandle. Moist isentropic lift will ramp up late Thursday, peaking
Friday morning. This should produce a rain shield north of the low
center, which will streak across the southern 2/3rd or so of the
forecast area. An unseasonably cold air mass will be in place, but
thicknesses support mainly a cold rain (with high-elevation wintry
mix or snow in the NC mountains). Pockets of light freezing rain
cannot be ruled out in the northern mountains (mainly the Toe River
valley) around daybreak Friday. Overall, confidence on even advisory-
level impact below like 5000 ft is still low. I have bumped up pop
to likely along and southeast of I-85 (and that will probably get increased
further in later updates). Precip should start to pivot east Friday
aftn, but things may not completely dry out in the east thru Friday
night. Quantitative precipitation forecast will be spotty along the Tennessee line, but could be 0.25-0.50"
along the southeast counties of the forecast area. Temps will be
mainly in the 30s Thursday night, warming to the mid 40s to lower
50s Friday. Temps will be a little cooler Friday night in the
mountains, as northerly flow increases around the developing coastal
low. But overlap of precip and sub-freezing temps doesn't look


Long term /Saturday through Wednesday/...
as of 230 PM wednesday: below normal temps will continue this
weekend, as cold high pressure builds in behind a departing coastal
low. Under mostly clear skies, highs mainly in the 50s and lows
ranging from the mid 20s to mid 30s.

The next deep trough will cross the eastern Continental U.S. Monday thru
Wednesday, being a largely consolidated/full-latitude in nature. The
trough will pivot to a negative tilt by Wednesday (and possibly
closing off into an upper low), but this will be just NE of the
forecast area. The medium range guidance is in relatively good
agreement that another coastal low will develop in response to this
trough, but with any direct impacts just skirting the East Coast.
The deep eastern trough will support below normal temps, but with a
gradual warming trend thru the middle of next week.


Aviation /00z Thursday through Monday/...
at kclt and elsewhere: expect VFR to prevail through tonight with
sfc high pressure in place, with gradually increasing high clouds
overnight. Towards daybreak, expect few/scattered high clouds to gradually
lower to low VFR scattered/broken by the late morning hours, as a system
develops along the Florida. Rain chances will gradually increase late in
the period from southeast to NW, with patchy fog possible Thursday night.
Winds will remain light and variable through the valid taf period,
predominately NE.

Outlook: a slow moving coastal low may bring a period of precipitation
and associated restrictions beginning later Thursday and potentially
lingering well into the weekend. Otherwise, expect VFR.

Confidence table...

00-06z 06-12z 12-18z 18-00z
kclt high 100% high 100% high 93% high 88%
kgsp high 100% high 100% high 92% high 84%
kavl high 100% high 100% high 100% high 98%
khky high 100% high 100% high 100% high 96%
kgmu high 100% high 100% high 90% high 82%
kand high 100% high 98% high 84% high 83%

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:



records for 11-13

Maximum temperature min temperature
station high low high low
------- ---------- ---------- ---------- ----------
kavl 75 1964 32 1906 58 1929 13 1911
kclt 81 1931 40 1920 63 1879 21 2013
kgsp 81 1909 40 1920 61 1929 20 1906

Records for 11-14

Maximum temperature min temperature
station high low high low
------- ---------- ---------- ---------- ----------
kavl 76 1999 32 1906 60 1929 16 1986
kclt 80 1879 37 1976 63 1961 21 2013
kgsp 79 2007 36 1976 62 1929 20 1906


Gsp watches/warnings/advisories...



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