Hail in Georgia, April 23, 2020

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
550 PM EDT Thu Apr 23 2020

.SYNOPSIS...
A cold front will cross the area tonight, ushering in dry high
pressure for Friday. Another crosses the forecast area Saturday,
followed by cool and dry high pressure for Sunday into early next
week.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 550 PM EDT Thursday: Minor adjustments made to
temperatures/PoPs to coincide with the latest trends as the rest
of the near term forecast remains on track. Conditions have
been fairly quiet over the last few hours across the area with
most of the activity well to the south. However, latest radar
imagery depicts storms beginning to develop back across north-
northeastern GA. Expect this activity to push into the Upstate
over the next few hours, with convection possible through this
evening across the area (except for the NC mountains). Though
the main concern will be the more stable/cooler environment in
place across the area attm. Will note SPCs newest run of the Day
1 convective outlook which has brought a marginal risk back
into portions of the area. A Wind Advisory remains in effect for
portions of the NC mountains through this evening.

Previous discussion: Low-lvl warm advection has increased over the
past few hours, and the stronger low-level jet is still expected to
transit the lower Piedmont over the next 4 to 8 hours. By that time,
we should see some better instability at least across our southern
zones. The best upper jet divergence will cross the region around
00Z, and the evening hours will have the best overlap of deep
forcing, a stout low-level jet, sfc-6 km bulk shear values at 60 kt
or better, and a surging warm sector generally southeast of I-85. If
any strong/severe convection develops, this appears to be the most
likely time window. Isolated tornadoes and damaging straight-line
winds are the main concerns, with large hail possible farther south.
Meanwhile, the upper shortwave will gradually weaken as it moves
over the central Appalachians overnight and into the morning. Low-
lvl moisture and lingering pre-frontal instability should continue
thru the overnight hours, but shear will diminish, mid and upper
lvls will dry out, and low-level flow will veer to a more SWLY
direction thereby reducing the severe threat. Nevertheless,
continued showers and isolated thunderstorms along the passing cold
front will be possible thru the overnight hours. The main flooding
threat continues to be from training storms, however a Flash Flood
Watch is not expected.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 230 PM Thursday: A really strong vort max will round the base
of a digging trough over the Mid-South early Saturday, then pivoting
NE to the Central Appalachians by Saturday evening. This will
produce strong DPVA atop the forecast area right at peak heating
Saturday aftn. At the sfc, a compact low pressure system will track
into the Ohio Valley and drag a cold front across the Southeast. The
system will have most of its own moisture to work with, but won't be
able to tap into much Gulf moisture. Despite this, steep mid-lvl
lapse rates should help things destabilize, with guidance showing
1000-1500 J/kg of sbCAPE across the Piedmont by 21z. Shear will be
supportive of organized storms, possibly supercells (SCP on the NAM
of 8-12). But with the lack of moisture, there is still uncertainty
on how much, if anything develops. For now, only a marginal severe
risk area in the Day 3 Outlook.

The system quickly passes by to our NE by early Sunday. There will
be plenty of lingering moisture along the TN border Saturday into
Sunday for NW flow showers, but temps looks too warm for any snow
(except perhaps the highest peaks). Conditions will become breezy to
windy by Sunday aftn, and with dewpts falling, there may be some
fire wx concerns. Temps will be slightly above normal Saturday,
and slightly below normal on Sunday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 250 PM Thursday: Deep upper trough will exit to our east
Monday, with quasi-zonal flow aloft thru Tuesday. The next trough
will dig across Upper Midwest Tuesday night into Wednesday, but the
GFS and ECMWF diverge quickly on that feature, with the EC closing
off a deep upper low over IL. Despite the differences, they both
show a strongly forced front crossing the forecast area either
during the day Wednesday or Wednesday night, depending on the
solution (the GFS is faster). Another polar air mass builds in
behind that front and could have some frost/freeze concerns for the
mountains by Thursday night. Otherwise, temps will be seasonable,
with chilly overnight lows both Sunday and Monday nights in the
mountains.

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
At KCLT and Elsewhere: Widespread showers have scattered out
over the past few hours with most sites currently reporting MVFR
cigs and a few reporting IFR. Cigs will likely hold thru the
rest of the day and into the evening with most sites expected
to go IFR by roughly 00z. I keep cigs at IFR thru the overnight
and then sct them out back to VFR around 14z tomorrow. Visby
could drop to IFR as well, however confidence is lower compared
to cigs. The best window for TSRA is trending a bit later and
the latest CAMs have the overall coverage looking less impressive.
Best window for convective development appears to be in the 22
to 03z timeframe with TEMPOs for TSRA for all sites except KAVL,
where chances look lower. For them, I just went with VCTS. Winds
will remain SLY to SELY thru the afternoon/evening with some
intermittent gusts likely. As the cold front approaches from
the west later tonight, winds will gradually veer around to a
more SWLY direction and eventually become WLY by tomorrow aftn.
Low-end gusts are likely again tomorrow aftn.

Outlook: After a dry Friday, another storm system may bring flight
restrictions, rainfall, and thunderstorms back on Saturday. Dry
conditions return the latter half of the weekend into early next
week.

Confidence Table...

            22-04Z        04-10Z        10-16Z        16-18Z
KCLT       Med   62%     Low   40%     Med   61%     High  97%
KGSP       High  92%     Med   75%     Low   52%     High 100%
KAVL       Med   67%     Med   72%     Low   47%     High  94%
KHKY       Med   70%     High  97%     High  83%     High  97%
KGMU       High  90%     High  87%     Med   72%     High 100%
KAND       High  95%     Med   77%     High  83%     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

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Wind Advisory above 3500 feet until 8 PM EDT this evening for
     NCZ051-052-058-059-062>064.
SC...None.

&&

SYNOPSIS...ARK
NEAR TERM...JPT/12
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JPT

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
444 PM EDT Thu Apr 23 2020

GAZ010-017-018-026-028-029-NCZ057-068>072-082-SCZ001>014-019-242045-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Rowan-Cleveland-
Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-Oconee Mountains-
Pickens Mountains-Greenville Mountains-Greater Oconee-
Greater Pickens-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
444 PM EDT Thu Apr 23 2020

This Hazardous Weather Outlook is for northeast Georgia, piedmont
North Carolina and upstate South Carolina.

.DAY ONE...Tonight.

Thunderstorms are possible this evening. Any thunderstorm will be
capable of cloud-to-ground lightning. A couple of the storms could
become severe, posing a risk of damaging winds and large hail.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

A cold front will approach the western Carolinas and northeast
Georgia Saturday. There is some uncertainty with the actual timing
of the frontal passage, but strong to possibly severe storms will be
possible from late morning through the afternoon.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ051-052-058-059-062>064-242045-
Swain-Haywood-Graham-Northern Jackson-Macon-Southern Jackson-
Transylvania-
444 PM EDT Thu Apr 23 2020

...WIND ADVISORY IN EFFECT UNTIL 8 PM EDT THIS EVENING ABOVE
3500 FEET...

This Hazardous Weather Outlook is for western North Carolina.

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Wind Advisory.

A few thunderstorms will develop this afternoon and linger into the
evening. These storms will be capable of producing gusty winds and
cloud to ground lightning.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

A cold front will approach the western Carolinas and northeast
Georgia Saturday. There is some uncertainty with the actual timing
of the frontal passage, but strong to possibly severe storms will be
possible from late morning through the afternoon.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ033-035>037-048>050-053-056-065-501>510-242045-
Avery-Alexander-Iredell-Davie-Madison-Yancey-Mitchell-Buncombe-
Catawba-Henderson-Caldwell Mountains-Greater Caldwell-
Burke Mountains-Greater Burke-McDowell Mountains-Eastern McDowell-
Rutherford Mountains-Greater Rutherford-Polk Mountains-Eastern Polk-
444 PM EDT Thu Apr 23 2020

This Hazardous Weather Outlook is for piedmont North Carolina and
western North Carolina.

.DAY ONE...Tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

A cold front will approach the western Carolinas and northeast
Georgia Saturday. There is some uncertainty with the actual timing
of the frontal passage, but strong to possibly severe storms will be
possible from late morning through the afternoon.

.SPOTTER INFORMATION STATEMENT...

None.

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