Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/09/20
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1037 PM EDT Fri May 8 2020
.SYNOPSIS...
A cold front sweeping across the area will bring colder Canadian air
for the weekend, which will maintain below normal temperatures and
possibly cause early morning frost and freeze conditions across the
region. Temperatures will rebound later next week as strong, dry
high pressure develops over the Atlantic.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1030 PM EDT...The axis of an upper trough is just pushing east
of us, taking the widespread light rain with it, and leaving just
some scattered NW flow showers along the TN border. A cold front is
roughly along the eastern escarpment, and should push across the
Piedmont over the next 2-3 hours. Meanwhile, there is some varying
degrees of lingering cloudiness seen on the RGB product and on area
metars. But most of this cloud cover should dissipate over the next
few hours, as cold and dry air filters in behind a passing cold
front. On the Beech Mountain web cam, it`s hard to tell if there`s
light snow or drizzle. But there was a Tweet from someone driving on
Roan Mountain with video of some heavy snow. This lines up with some
echoes on radar, but is fairly isolated. Still expect just spotty
light snow accums, as moisture becomes limited by the time the
colder air really sets in.
As for the Frost/Freeze concerns, the advective freeze in the
mountains looks good. And while the evening is starting out mild and
mixed, with cloud cover, conditions are expected to become more
supportive of frost by daybreak in the current Frost Advisory area.
So no changes were made to that with the evening update.
High pressure will build in on Saturday, giving us a sunny but
cool and very dry day. Temps will top out nearly 15 degrees below
normal, more typical of mid-March.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 215 pm EDT Friday: Anomalously deep/cold upper trough
dominating East Coast weather will be reinforced by another region
of height falls/associated cold front on Sunday/Sun night. Sprawling
dry surface high pressure covering much of the Southeast means that
the Gulf is more or less closed for business, so this front will be
primarily dry, although an isolated shower cannot be ruled out over
the mtns late Sunday. The main story will therefore continue to be
temperatures, which will be 10-15 degrees below climo through the
period. This will place much of the forecast area into at least
frost territory Sunday morning, and it in fact appears that
widespread freezing temps are likely across the mtns...and are at
least a good bet across the northern foothills and far northern
Piedmont of NC. A Freeze Watch is therefore being issued for those
areas. Better mixing should yield a bit warmer conditions Sunday
night, although at least patchy frost will again be possible in
sheltered mountain valleys.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 230 pm EDT Friday: During the medium range, the atmosphere is
going to skip the formalities...with a quick transition from early
spring to late spring expected as low amplitude is forecast to build
across the East. As such, although the cool weather of the short
term will extend into the early part of the extended, above-normal
temps are likely by Thu, with max temps in the lower 80s expected to
be widespread across the forecast area by the end of the week.
Conditions will generally remain dry. However, with SW return flow
finally expected to set up during mid-week, gradually increasing
dewpoints combined with the increasing heat may yield sufficient
instability for diurnal convection to fire...mainly over the high
terrain Thu and Fri afternoon.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and Elsewhere: At time of the 00z TAF issuance, a cold front
was seen over eastern TN. The front should push thru the area late
this evening. Before fropa, generally 5-7 kft cigs, with spotty 1500-
3500 ft cigs out there. May see brief MVFR cigs at mainly KHKY/KCLT,
but also possibly KAND with low clouds just to the west over
northern GA. But overall, flow will turn westerly then
northwesterly, and this will lift and scatter the low cigs out by
around 4-5z, and mid and high clouds clear during the pre-dawn
hours. Winds start out SW/WSW, then shift to N/NW with fropa. They
should really pick up and become gusty at KAVL, with channeling up-
valley flow. Not expecting much gusts at the other sites, except
possibly a gap wind at KGSP/KGMU from the north, but confidence is
low on how persistent those would be. Deep mixing after daybreak
will likely result in more frequent gusts at all sites thru early
aftn.
Outlook: Frost on aircraft could become an issue over the weekend,
especially Sunday morning. Otherwise expect VFR.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 97% High 100% High 100% High 100%
KAVL High 87% High 98% High 100% High 100%
KHKY Med 71% High 100% High 100% High 100%
KGMU High 97% High 100% High 100% High 100%
KAND High 98% 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 are available at
the following link:
www.weather.gov/gsp/aviation
&&
.CLIMATE...
RECORDS FOR 05-09
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 90 1889 48 1908 65 1979 34 1984
KCLT 94 1889 60 1923 69 1916 39 1984
1906
1893
KGSP 96 1916 58 1989 70 2003 35 1917
1985 1979
1917
RECORDS FOR 05-10
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 89 1936 53 1924 65 1927 32 1966
1896 1906
KCLT 94 1896 59 1966 70 1927 38 1906
1889
KGSP 96 1889 56 1924 71 1895 32 1906
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Freeze Warning until 10 AM EDT Saturday for GAZ010.
Frost Advisory until 10 AM EDT Saturday for GAZ017-018.
NC...Freeze Watch from late Saturday night through Sunday morning
for NCZ033-035>037-048>053-058-059-062>065-501>506.
Freeze Warning until 10 AM EDT Saturday for NCZ033-048>053-058-
059-062>065-501-503-505-507-509.
Frost Advisory until 10 AM EDT Saturday for NCZ035>037-056-057-
068-069-502-504-506-508-510.
SC...Frost Advisory until 10 AM EDT Saturday for SCZ001>003.
&&
$$
SYNOPSIS...JDL
NEAR TERM...ARK/PM
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...ARK
CLIMATE...GSP