NWS Greenville-Spartanburg, SC wrote its last area forecast discussion before the first event at Apr 13, 5:54 AM EST, 3 hours 36 minutes earlier.
Area forecast discussion, Apr 13, 5:54 AM EST, 3 hours 36 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
654 AM EDT Sat Apr 13 2019
.SYNOPSIS...
A weak cold front will stall across the region through Saturday
maintaining a chance of showers and storms. A stronger system will
bring more widespread storms to the area on Sunday and Sunday night,
with severe weather possible. The weather will improve significantly
through mid-week next week, with the next system expected Thursday
through Friday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 650 am: Deep/moderately strong SW flow will persist across the
Southeast through the near term, downstream of a strong cyclone that
will impact the lower Miss Valley and surrounding areas today. The
gradient between this cyclone and quasi-stationary high pressure
over the western Atlantic will continue to supply ample low level
moisture to our area through the period. Surface analysis reveals an
axis of low level confluence persisting along the western periphery
of this area of high pressure, and this has been responsible for
initiation of scattered to numerous coverage of deep convection
(mainly in the form of showers) across the eastern third of the
forecast area over the past couple of hours. Pops have been
increased to 60-80% across the southern NC and eastern SC Piedmont
through about mid-morning, with only a token 20-30% across much of
the remainder of the area.
As the day progresses, and the surface cyclone deepens across the
Arklatx, a broad warm sector will become established across the
Southeast, and the thermodynamic environment will become
increasingly typical of a warm sector air mass, i.e., unstable but
also somewhat capped. As such, guidance more or less agrees in the
idea of convection being most likely this morning, although the
unstable air mass interacting with differential heating and related
terrain effects warrants maintaining at least a slight chance
through the afternoon. Can't rule out a stray severe storm today,
but the greater risk should exist to our east, where convective
coverage should be greater during the afternoon.
Tonight will see accelerating southerly flow in advance of cold
front marching across the TN Valley. Very gusty winds will develop
on the high peaks and ridge tops of the southern Appalachians, with
advisory-level winds most likely being contained to elevations above
4000 ft (or higher) in the warm advection flow. Increasing
mechanical lift near the Blue Ridge escarpment will also lead to
increasing chances for showers/perhaps a TS or two through the
night. Temps will remain well above normal through the period.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 345 AM EDT Saturday: Per latest guidance, confidence for the
risk of severe weather continues to increase for Sunday and Sunday
night for northeast GA and the western Carolinas. The entire
forecast area is under an Enhanced Risk for the Day 2 Convective
Outlook from the Storm Prediction Center. Numerous strong to severe
thunderstorms will be possible.
Northeast GA and the western Carolinas will be well situated in the
warm sector beginning Sunday morning as temperatures are expected to
already be in the mid to upper 60s east of the escarpment around
daybreak, with dewpoints in the mid 60s. With the approaching cold
front well to the west as it's parent sfc low pressure enters the TN
Valley and it's warm front remains to the north in the morning,
temperatures will climb throughout the day into the mid to upper 70s
(again east of the escarpment), remaining slightly cooler across the
mountains. Latest guidance continues to prog the sharp, digging
upper trough entering the MS Valley throughout the morning hours,
slowly propagating eastward and moving overhead the Carolinas Monday
morning. Ahead of this feature, expect the parent sfc low to push
eastward and then lift northeastward roughly along the Appalachian
mountains as it's associated cold front pushes through the FA Sunday
evening through the overnight hours.
Ahead of the cold front will be the window of opportunity for strong
to severe thunderstorms on Sunday and Sunday night across the FA.
Guidance continues to hint at the possibility of prefrontal
convection earlier in the day before the main line/QLCS pushes
through the area Sunday afternoon/early evening. Whether or not the
timing of any prefrontal activity will affect the instability of the
atmosphere for afternoon convection remains a primary question at
this time, though keep in mind this is quite the dynamic system. The
main line looks to coincide with daytime peak heating and the more
favorable forcing/upper dynamic support (quite the healthy LLJ
around 50kt+), despite SBCAPE values 1200-1400 J/kg primarily east
of the escarpment. Overall, the severe weather threat will still
apply to the entire FA. The main notable severe weather parameters
continue to be the deep layer shear anticipated across the Carolinas
and northeast GA. Both the NAM and GFS continue to prog 0-6km bulk
shear values roughly 5 kts higher than the ECWMF, but overall
looking at a range of 50 to 60 kts. The primary threat with these
storms will be damaging straight line winds, however, large hail and
an isolated tornado cannot be ruled out. In addition, with PWATs
over 1.5 inches and given the potential for training storms along
with rainfall over the past few days and saturated soils, cannot
entirely rule out isolated flash flooding on Sunday as well.
A drying trend is expected overnight Sunday into Monday behind the
cold front as upper troughing shifts eastward offshore and sfc high
pressure builds in from the GOM. High temperatures on Monday will
range from the mid to upper 60s east of the escarpment, cooler into
the 50s/60s across the mountains, with clearing skies. Overnight low
temperatures will drop to near or just below normal.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 230 AM EDT Saturday: Expect a dry weather pattern to kick off
the extended forecast period on Tuesday as sfc high pressure
dominates the weather pattern with semi-flattened upper ridging
aloft across much of the CONUS. Into Wednesday, latest guidance
continues to shift sfc high pressure eastward off the Carolinas
coast as, back to the west, upper ridge builds ahead of the next
approaching weather system. While timing remains the main question
for the next approaching system, latest guidance overall continues
to trend towards a cold front pushing through northeast GA and the
western carolinas on Friday. With this system, expect shower and
thunderstorm chances to return, with an unsettled weather pattern on
tap for the end of the week.
Temperatures will remain above normal through the period, with high
temperatures nearing 80 degrees on Wednesday and Thursday along and
south of the I-85 corridor. Overnight low temperatures will remain
above normal as well.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Convection, mainly in the form of showers,
but with isolated TS as well, continued to impact KCLT and vicinity
this morning. Tempo for TSRA continues there through 14Z. Convection
is also beginning to initiate farther west toward KGSP/KGMU, so a
VCSH appears prudent there, but confidence is not high enough to
include a tempo attm. Otherwise, IFR/LIFR will continue at all sites
except KAVL/KHKY through about 15Z. Reduced visby will also continue
until about that time, due to precip at KCLT and due to FG/BR at the
Upstate SC terminals.
Flt conditions will improve at sites currently experiencing
restrictions after 15Z or so, likely becoming MVFR by late morning,
and VFR by mid-afternoon or so. While small chances for convection
will persist through the day, especially for the sites west of KCLT
(where VCSH/VCTS and/or Prob30s are carried), the best chances near
KCLT should remain during the morning hours, as the atmosphere is
expected to become somewhat less conducive to convection during the
afternoon and evening. Cigs will again lower to at least MVFR
tonight, with IFR becoming possible, if not probable by the end of
the period. Light NE winds this morning gradually veer to south of
due east by mid-afternoon, steadily increasing during the evening
and overnight, with south winds at 10-15 kts, with higher gusts
possible at most terminals by 12Z Sunday.
Outlook: Visby and/or cig restrictions will likely persist into
Sunday and Sunday night ahead of and along an approaching strong
cold front. Numerous to widespread showers and thunderstorms are
expected Sunday, some of which will be strong to severe. VFR
conditions should return early next week behind the cold front, and
likely continue through mid-week.
Confidence Table...
11-17Z 17-23Z 23-05Z 05-06Z
KCLT Med 62% Med 66% High 94% High 100%
KGSP Med 75% High 94% High 100% High 87%
KAVL High 100% High 100% High 100% Med 69%
KHKY High 81% High 89% High 94% High 94%
KGMU Med 62% High 100% High 100% High 87%
KAND Med 69% High 94% High 100% High 94%
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:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
SYNOPSIS...JMP
NEAR TERM...JDL
SHORT TERM...SGL
LONG TERM...SGL
AVIATION...JDLSpecial weather statement, Apr 13, 8:37 AM EST, 53 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
937 AM EDT Sat Apr 13 2019
NCZ057-131415-
Rowan NC-
937 AM EDT Sat Apr 13 2019
...A THUNDERSTORM WITH INTENSE LIGHTNING AND TORRENTIAL RAINFALL WILL
IMPACT SOUTHEASTERN ROWAN COUNTY UNTIL 1015 AM EDT...
At 937 AM EDT, Doppler radar was tracking a thunderstorm with intense
lightning and torrential rainfall 4 miles southeast of Salisbury, or
over Granite Quarry, moving northeast at 25 mph.
Locations to be impacted include...
Salisbury, Kannapolis, China Grove, Spencer, Landis, Granite Quarry,
Rockwell, Faith, High Rock Lake and Gold Hill.
Torrential rainfall rates up to 3 inches per hour will be possible in
these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
Frequent lightning is occurring with this storm. If outdoors, try to
get indoors or into a hard topped vehicle. Otherwise, stay away from
open areas and isolated high objects such as trees. When indoors,
stay away from windows and doors and avoid using wired electronic
devices. Do not take a shower or bath. Try to unplug unnecessary
appliances before the storm approaches.
&&
LAT...LON 3550 8023 3551 8064 3576 8047 3573 8045
3572 8038 3572 8035 3571 8032 3568 8033
3567 8031 3563 8029 3563 8027 3559 8021
3555 8021 3553 8019
TIME...MOT...LOC 1337Z 223DEG 21KT 3561 8044
JMP