LLJ rocking the Coast here, SSW winds @ 28 MPH or so..
Local NWS forecast Grid..
**
.SYNOPSIS...
Strong to severe thunderstorms are expected tonight into early
Tuesday morning, with damaging winds being the main threat,
while large hail and isolated tornadoes are also possible. Dry
and seasonably warm weather is expected for the middle of the
week, but humidity will increase by Friday as southerly winds
develop.
&&
.UPDATE...
Updated POPs slightly slower on precip onset timing. Radar
continues to light up to our northwest. Activity will begin to
move into our far NW counties in the next couple hours.
The 850mb LLJ is slowly starting to crank up,
with 25kts captured at 2000-3000ft, per the latest KLTX VAD Wind
Profile. The LLJ will increase in intensity this evening, with
the left exit region of the jet streak coming into play to the
northwest. Back at the surface, a cold front drapes off the
surface low, sinking into the Ohio River Valley, hiking into
Appalachia, and flattening out just north of ArkLaTex. A
Piedmont trough commands a hold inland. The surface front alone
has been an interesting feature today, as it has barely moved
from this morning. This plays a potential role later...keep
reading.
Here lies one of the best severe weather setups we`ve had in the
last year or so. The Storm Prediction Center (SPC) carries a
"Slight Risk" (threat level 2/5) across most of northeast SC
into parts of the immediate Cape Fear region. Just to the north,
an "Enhanced Risk" (threat level 3/5) persists, which is rather
rare for these parts. Radar feeds remain mostly dry at this
time, with only a few showers moving eastward across the NC/VA
border, which has been a very recent trend. The front will
continue its slow approach eastward, progressing through
Appalachia this evening, and through the Piedmont during the
overnight hours. Showers and thunderstorms will start to fire
ahead of the front and along the Piedmont trough.
High-resolution guidance paints a favorable environment for
severe weather locally. Even with the loss of diurnal heating,
MLCAPE hangs securely in the 2000-2500J/kg range. Bulk shear
hits 30-40kts, with the 0-1km shear hitting 20-25kts. Moisture
kicks up even more overnight, particularly at the coast, with
PWATs hitting at or above 2 inches. DCAPE might eclipse 1500J/kg
in some cases. Low-level lapse rates go to 7C/km, which is not
necessarily unusual around here. What is a little more unusual,
however, is that the mid-level lapse rates hit the same mark.
Most of the CAMs seem to cap the SRH at 150m2/s2 at most levels,
but multiple runs of the HREF show a bullseye of 200-300m2/s2
at 0-3km in northeast SC, which could lead to more significant
concerns with hail and tornadoes specifically. The caveat there
is that there are several ensemble members that contribute to
the HREF that are much too fast with the timing of the storms.
This may also have an impact on the way the model is outputting
some of the severe weather indices. Time will tell.
Bottom line: Strong to severe showers and thunderstorms expected
tonight, with damaging winds being the main concern, while
isolated large hail and tornadoes also possible. Considering the
slow motion of the front and lack of convective initiation this
afternoon, the timing seems to have slowed down a touch from
last night`s big forecast update. Confidence is increasing on a
more nocturnal event, particularly closer to the coast. Best
chance for inland areas to have severe weather appears to be 8
PM - 1 AM EDT west of Highway 701. East of 701, chances get
better in the 1 AM - 5 AM EDT. Depending on how slow the front
is, along with its interaction with the Piedmont trough, some of
this timing may change, and may slow down more still. Some
areas may actually experience two rounds of severe weather, as
the northern periphery of the front looks like a faster, more
easterly progression, while the southern one carries a slower,
more south-southeasterly tilt. Nocturnal inversion looks to
build in early, which may help protect the surface from some of
the severe winds. However, with a more robust setup like this,
not sure how much that helps, particularly with the elevated
DCAPE values, which help promote strong downdrafts.
Big thing here is a nocturnal severe weather event. HAVE A WAY
TO RECEIVE WARNINGS IN THE MIDDLE OF THE NIGHT WHEN YOU ARE
ASLEEP! Charge your devices just in case.
Local NWS forecast Grid..
**
.SYNOPSIS...
Strong to severe thunderstorms are expected tonight into early
Tuesday morning, with damaging winds being the main threat,
while large hail and isolated tornadoes are also possible. Dry
and seasonably warm weather is expected for the middle of the
week, but humidity will increase by Friday as southerly winds
develop.
&&
.UPDATE...
Updated POPs slightly slower on precip onset timing. Radar
continues to light up to our northwest. Activity will begin to
move into our far NW counties in the next couple hours.
The 850mb LLJ is slowly starting to crank up,
with 25kts captured at 2000-3000ft, per the latest KLTX VAD Wind
Profile. The LLJ will increase in intensity this evening, with
the left exit region of the jet streak coming into play to the
northwest. Back at the surface, a cold front drapes off the
surface low, sinking into the Ohio River Valley, hiking into
Appalachia, and flattening out just north of ArkLaTex. A
Piedmont trough commands a hold inland. The surface front alone
has been an interesting feature today, as it has barely moved
from this morning. This plays a potential role later...keep
reading.
Here lies one of the best severe weather setups we`ve had in the
last year or so. The Storm Prediction Center (SPC) carries a
"Slight Risk" (threat level 2/5) across most of northeast SC
into parts of the immediate Cape Fear region. Just to the north,
an "Enhanced Risk" (threat level 3/5) persists, which is rather
rare for these parts. Radar feeds remain mostly dry at this
time, with only a few showers moving eastward across the NC/VA
border, which has been a very recent trend. The front will
continue its slow approach eastward, progressing through
Appalachia this evening, and through the Piedmont during the
overnight hours. Showers and thunderstorms will start to fire
ahead of the front and along the Piedmont trough.
High-resolution guidance paints a favorable environment for
severe weather locally. Even with the loss of diurnal heating,
MLCAPE hangs securely in the 2000-2500J/kg range. Bulk shear
hits 30-40kts, with the 0-1km shear hitting 20-25kts. Moisture
kicks up even more overnight, particularly at the coast, with
PWATs hitting at or above 2 inches. DCAPE might eclipse 1500J/kg
in some cases. Low-level lapse rates go to 7C/km, which is not
necessarily unusual around here. What is a little more unusual,
however, is that the mid-level lapse rates hit the same mark.
Most of the CAMs seem to cap the SRH at 150m2/s2 at most levels,
but multiple runs of the HREF show a bullseye of 200-300m2/s2
at 0-3km in northeast SC, which could lead to more significant
concerns with hail and tornadoes specifically. The caveat there
is that there are several ensemble members that contribute to
the HREF that are much too fast with the timing of the storms.
This may also have an impact on the way the model is outputting
some of the severe weather indices. Time will tell.
Bottom line: Strong to severe showers and thunderstorms expected
tonight, with damaging winds being the main concern, while
isolated large hail and tornadoes also possible. Considering the
slow motion of the front and lack of convective initiation this
afternoon, the timing seems to have slowed down a touch from
last night`s big forecast update. Confidence is increasing on a
more nocturnal event, particularly closer to the coast. Best
chance for inland areas to have severe weather appears to be 8
PM - 1 AM EDT west of Highway 701. East of 701, chances get
better in the 1 AM - 5 AM EDT. Depending on how slow the front
is, along with its interaction with the Piedmont trough, some of
this timing may change, and may slow down more still. Some
areas may actually experience two rounds of severe weather, as
the northern periphery of the front looks like a faster, more
easterly progression, while the southern one carries a slower,
more south-southeasterly tilt. Nocturnal inversion looks to
build in early, which may help protect the surface from some of
the severe winds. However, with a more robust setup like this,
not sure how much that helps, particularly with the elevated
DCAPE values, which help promote strong downdrafts.
Big thing here is a nocturnal severe weather event. HAVE A WAY
TO RECEIVE WARNINGS IN THE MIDDLE OF THE NIGHT WHEN YOU ARE
ASLEEP! Charge your devices just in case.
