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fxus62 kgsp 180543 

Area forecast discussion
National Weather Service Greenville-Spartanburg SC
1243 am EST Mon Nov 18 2019

seasonably cool conditions are expected early this week. A couple
of minor disturbances may bring light precipitation to some areas
as they pass through. Temperatures will gradually warm Wednesday
and Thursday ahead of the next cold front expected late in the week.


Near term /through today/...
as of 140 am: guidance has come into better agreement showing precip
developing and spreading across the area this morning as a short
wave moves into the area. Have adjusted pop to show these trends.
Temps continue to only slowly cool with the increased cloud cover.
This will keep precip as all liquid.

Previous discussion: the pattern becomes more progressive tonight
and Monday as a strong short wave comes in from the W/NW to kick out
the old upper low off the NC coast. The sensible weather will be
fair and dry this evening as high pressure ridges down from the
northeast, however, its influence will diminish as the short wave
moves in toward daybreak Monday. Remaining low level moisture will
be trapped under the persistent subsidence inversion, thus it is
likely we will cloud up again overnight. What remains to be seen is
if the wave, which will acquire a negative tilt, will have enough
moisture to go along with the mid/upper forcing to bring some light
precip to the area in the early/middle part of the morning. Not
really buying the extent of precip in the operational models and
prefer the lower probs seen in blended guidance, mainly because
whatever falls is unlikely to be more than a trace. Temps will be
borderline concerning the small potential that a few snow flakes
could fall at the high elevations. Think this is not Worth
mentioning at this point because it is highly unlikely to cause any
problems. Low temps will be close to normal. On Monday, the short
wave quickly pivots on past and we end up in a fast cyclonic flow at
the bottom of the upper trof in the afternoon, so we can look
forward to clearing in the afternoon with temps rising a few degrees
warmer than today because of the strong downslope flow east of the


Short term /tonight through Wednesday/...
as of 1:30pm EST sunday: Monday night, area will be on the back side
of the mostly dry upper system that passed through on Monday. Upper
trough will continue to makes its way up the East Coast with
northwesterly flow aloft over the gsp region as well as
northwesterly flow behind the frontal system at the surface. This
flow pattern will keep moisture out of the area through Wednesday,
with upper pattern progressing and flattening ahead of next system
due later in the week. Temperatures will be at or slightly above
seasonal normals Tuesday and Wednesday with mild northerly to
northwesterly surface winds. Strong drying from northwest flow will
producing mostly clear conditions on Tuesday, with clear skies on


Long term /Wednesday night through Sunday/...
as of 2pm EST sunday: next chance for significant precipitation
lies in the Friday to Saturday time period where both the ec and GFS
models are in fairly good agreement on timing of next system, a
complicated longwave trough with a large piece of energy entering
the Great Lakes region Thursday night connected with a second piece
over the 4-corners region. This system shoves flattening ridge over
the gsp region eastward Thursday morning, and manifests at the
surface as a well-defined significant front that reaches the Tennessee
state line area Friday afternoon, progressing across the gsp area on
Friday. Timing errors in this forecast, of course, are at least a
half day this far out in the forecast. The Friday frontal passage is preceded
by a shift in winds from northerly to southwesterly on Thursday,
along with a strong advance in moisture/dewpoints with dewpoints
rising 5 to 10 degrees on Friday. Passage of front and upper system
gives a good chance from rain in the Friday-Saturday period, with
GFS and ec both suggesting amounts around a tenth to a half inch of
moistly rain. 850mb temps are cold enough behind the front for a
chance for some snow at the highest elevations Friday night.

Behind the front Saturday and Sunday, models diverge significantly,
with ec showing southern stream shortwaves causing a continued
chance for precipitation, while the GFS scours moisture out of the
area. Temperatures will remain just above normal ahead of the cold
frontal passage on Friday, dropping 5 to 10 degrees on Saturday behind it.
Windiest period in the forecast will be ahead of front on Friday,
with southwesterly winds of 10 to 20 mph.


Aviation /06z Monday through Friday/...
for kclt and elsewhere: guidance now in better agreement that rain
and low clouds develop by daybreak ahead of an approaching short
wave. Vsby restrictions will also accompany the rain. Low clouds
scatter out and rain and vsby restrictions end from west to east
from late morning through the afternoon as the wave moves east of
the area. VFR continues through the evening. Fog and possibly low
stratus returns across the area overnight. NE wind this morning
becomes light northwest or light and variable for the afternoon. Light and
variable winds expected overnight. Kavl the exception with light south-southeast
wind early this morning becoming north-northwest after daybreak and remaining
there overnight.

Outlook: VFR, except for morning Mountain Valley fog through
Thursday. Precipitation and associated restrictions expected for

Confidence table...

05-11z 11-17z 17-23z 23-00z
kclt high 100% high 100% high 94% 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:



Gsp watches/warnings/advisories...



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