• Hello, please take a minute to check out our awesome content, contributed by the wonderful members of our community. We hope you'll add your own thoughts and opinions by making a free account!

Observations Fright Night Halloween Week Severe Obs

From former WRAL met Greg Fishel.

COULD BE A LITTLE ROUGH LATER THIS EVENING

A very strong cold front (temps in the 40s right now in Nashville, TN) is just west of Knoxville, Tennessee and will arrive in the Triangle around 8-10pm this evening. Very strong winds exist at all levels of the atmosphere along with that all important "turning" of the winds with height that we always look for. Clouds are beginning to thin out a bit to our southwest, so a little sun will probably be observed this afternoon, only adding fuel to the fire for the evening storms. Now it is true that these storms will not be blazing through at time of maximum heating, but it still appears that there will be plenty of instability present to support strong storms. Hail is not a threat with these storms, but damaging straight line winds are, and a few tornadoes cannot be ruled out.
 
Brick Tamland said:
From former WRAL met Greg Fishel.

COULD BE A LITTLE ROUGH LATER THIS EVENING

A very strong cold front (temps in the 40s right now in Nashville, TN) is just west of Knoxville, Tennessee and will arrive in the Triangle around 8-10pm this evening. Very strong winds exist at all levels of the atmosphere along with that all important "turning" of the winds with height that we always look for. Clouds are beginning to thin out a bit to our southwest, so a little sun will probably be observed this afternoon, only adding fuel to the fire for the evening storms. Now it is true that these storms will not be blazing through at time of maximum heating, but it still appears that there will be plenty of instability present to support strong storms. Hail is not a threat with these storms, but damaging straight line winds are, and a few tornadoes cannot be ruled out.
Click to expand...
This is a DANGEROUS SITUATION. This storm has produced widespread
wind damage across Roane County. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows.
nws issued pds svr. @Fountainguy97 better look out
 
MCD suggests a watch is likely for parts of western NC soon.
 
mcd2128.gif


Mesoscale Discussion 2128
NWS Storm Prediction Center Norman OK
1012 AM CDT Thu Oct 31 2019

Areas affected...Parts of eastern North Carolina...northeastern
Tennessee...southwestern Virginia...far eastern Kentucky...West
Virginia and southwestern Pennsylvania

Concerning...Severe potential...Watch likely

Valid 311512Z - 311715Z

Probability of Watch Issuance...80 percent

SUMMARY...A more substantial increase in potential for severe wind
gusts, and perhaps isolated tornadoes, is expected with a developing
line of storms during the 1-3 PM EDT time frame. One or more
watches probably will be needed within the next couple of hours.

DISCUSSION...Although mid/upper-level lapse rates across much of the
region are more or less moist adiabatic, latest objective analysis
suggests that boundary layer warming and moistening are contributing
to at least weak destabilization along the western slopes of the
Allegheny Mountains. Mixed-layer CAPE may not become much more than
roughly 500 J/kg, but this is expected to occur in the presence of
strengthening lower/mid tropospheric wind fields, as deepening of
the surface cyclone (now centered near Columbus OH) proceeds more
rapidly through early to mid afternoon.

Model forecast soundings indicate south to southwesterly flow
intensifying to 50-70+ kt, just off the surface through around 500
mb, as the strengthening surface cold front advances toward the
Alleghenies. This is expected to coincide with increasing lift
along/ahead of the cold front, aided by forcing for upward vertical
motion ahead of a vigorous short wave trough gradually pivoting east
of the the Mississippi Valley, to support an intensifying line of
thunderstorms.

It is possible that this may be gradually underway across parts of
northeastern Tennessee through eastern Kentucky and southeastern
Ohio, but a more notable increase/intensification seems more likely
during the 17-19Z time frame, before gradually spreading eastward
into/through the Appalachians.

As convection intensifies, downward momentum transport in downdrafts
will contribute to increasing potential for damaging convective
surface gusts. Large low-level hodographs could also support
supercell structures along and perhaps just ahead of the developing
line of storms, with a risk for tornadoes.

..Kerr/Grams.. 10/31/2019
 
Brick Tamland said:
mcd2128.gif


Mesoscale Discussion 2128
NWS Storm Prediction Center Norman OK
1012 AM CDT Thu Oct 31 2019

Areas affected...Parts of eastern North Carolina...northeastern
Tennessee...southwestern Virginia...far eastern Kentucky...West
Virginia and southwestern Pennsylvania

Concerning...Severe potential...Watch likely

Valid 311512Z - 311715Z

Probability of Watch Issuance...80 percent

SUMMARY...A more substantial increase in potential for severe wind
gusts, and perhaps isolated tornadoes, is expected with a developing
line of storms during the 1-3 PM EDT time frame. One or more
watches probably will be needed within the next couple of hours.

DISCUSSION...Although mid/upper-level lapse rates across much of the
region are more or less moist adiabatic, latest objective analysis
suggests that boundary layer warming and moistening are contributing
to at least weak destabilization along the western slopes of the
Allegheny Mountains. Mixed-layer CAPE may not become much more than
roughly 500 J/kg, but this is expected to occur in the presence of
strengthening lower/mid tropospheric wind fields, as deepening of
the surface cyclone (now centered near Columbus OH) proceeds more
rapidly through early to mid afternoon.

Model forecast soundings indicate south to southwesterly flow
intensifying to 50-70+ kt, just off the surface through around 500
mb, as the strengthening surface cold front advances toward the
Alleghenies. This is expected to coincide with increasing lift
along/ahead of the cold front, aided by forcing for upward vertical
motion ahead of a vigorous short wave trough gradually pivoting east
of the the Mississippi Valley, to support an intensifying line of
thunderstorms.

It is possible that this may be gradually underway across parts of
northeastern Tennessee through eastern Kentucky and southeastern
Ohio, but a more notable increase/intensification seems more likely
during the 17-19Z time frame, before gradually spreading eastward
into/through the Appalachians.

As convection intensifies, downward momentum transport in downdrafts
will contribute to increasing potential for damaging convective
surface gusts. Large low-level hodographs could also support
supercell structures along and perhaps just ahead of the developing
line of storms, with a risk for tornadoes.

..Kerr/Grams.. 10/31/2019
Click to expand...
So possibly this could turn out to be a derecho?
 
Nick_boynton_ said:
Look deeper... the tornado and wind probabilities have increased .. this is an “upper” end enhanced risk
Click to expand...
And this is a moderate risk because of the 45 wind, but it is an enhanced risk due to the sig not being there.
day1probotlk_1630_wind.gif
 
Tornado watches issued
TORNADO WATCH OUTLINE UPDATE FOR WT 685
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM EDT THU OCT 31 2019

TORNADO WATCH 685 IS IN EFFECT UNTIL 700 PM EDT FOR THE
FOLLOWING LOCATIONS

NCC005-009-189-312300-
/O.NEW.KWNS.TO.A.0685.191031T1645Z-191031T2300Z/

NC
. NORTH CAROLINA COUNTIES INCLUDED ARE

ALLEGHANY ASHE WATAUGA
$$
TORNADO WATCH OUTLINE UPDATE FOR WT 685
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM EDT THU OCT 31 2019

TORNADO WATCH 685 IS IN EFFECT UNTIL 700 PM EDT FOR THE
FOLLOWING LOCATIONS

TNC019-091-163-171-179-312300-
/O.NEW.KWNS.TO.A.0685.191031T1645Z-191031T2300Z/

TN
. TENNESSEE COUNTIES INCLUDED ARE

CARTER JOHNSON SULLIVAN
UNICOI WASHINGTON
$$
TORNADO WATCH OUTLINE UPDATE FOR WT 685
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM EDT THU OCT 31 2019

TORNADO WATCH 685 IS IN EFFECT UNTIL 700 PM EDT FOR THE
FOLLOWING LOCATIONS

VAC021-027-051-071-077-155-167-169-173-185-191-195-197-520-640-
720-312300-
/O.NEW.KWNS.TO.A.0685.191031T1645Z-191031T2300Z/

VA
. VIRGINIA COUNTIES INCLUDED ARE

BLAND BUCHANAN DICKENSON
GILES GRAYSON PULASKI
RUSSELL SCOTT SMYTH
TAZEWELL WASHINGTON WISE
WYTHE


VIRGINIA INDEPENDENT CITIES INCLUDED ARE

BRISTOL GALAX NORTON
$$
TORNADO WATCH OUTLINE UPDATE FOR WT 685
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM EDT THU OCT 31 2019

TORNADO WATCH 685 IS IN EFFECT UNTIL 700 PM EDT FOR THE
FOLLOWING LOCATIONS

WVC001-005-007-013-015-017-019-021-025-033-039-041-043-045-047-
055-059-063-067-075-081-083-085-087-089-091-095-097-101-105-109-
312300-
/O.NEW.KWNS.TO.A.0685.191031T1645Z-191031T2300Z/

WV
. WEST VIRGINIA COUNTIES INCLUDED ARE

BARBOUR BOONE BRAXTON
CALHOUN CLAY DODDRIDGE
FAYETTE GILMER GREENBRIER
HARRISON KANAWHA LEWIS
LINCOLN LOGAN MCDOWELL
MERCER MINGO MONROE
NICHOLAS POCAHONTAS RALEIGH
RANDOLPH RITCHIE ROANE
SUMMERS TAYLOR TYLER
UPSHUR WEBSTER WIRT
WYOMING
$$


ATTN...WFO...JKL...RLX...RNK...MRX...
TORNADO WATCH OUTLINE UPDATE FOR WT 685
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM EDT THU OCT 31 2019

TORNADO WATCH 685 IS IN EFFECT UNTIL 700 PM EDT FOR THE
FOLLOWING LOCATIONS

KYC195-312300-
/O.NEW.KWNS.TO.A.0685.191031T1645Z-191031T2300Z/

KY
. KENTUCKY COUNTIES INCLUDED ARE

PIKE
$$
Click to expand...
 
mcd2129.gif

Mesoscale Discussion 2129
NWS Storm Prediction Center Norman OK
1211 PM CDT Thu Oct 31 2019

Areas affected...Parts of northern North Carolina...much of
Virginia...western and central Maryland...south central Pennsylvania

Concerning...Severe potential...Watch likely

Valid 311711Z - 311945Z

Probability of Watch Issuance...95 percent

SUMMARY...One or more severe weather watches will likely be needed
east of the Allegheny and Blue Ridge Mountains by 4-5 PM EDT.
However, isolated severe storm development, including a risk for
supercells, could require an earlier watch (likely tornado)
issuance.

DISCUSSION...Low-level and deep-layer shear are already strong to
extreme across and east of the Allegheny and Blue Ridge Mountains,
within deepening lee surface troughing, to the southeast of the
intensifying surface cyclone now approaching Lake Erie. Despite
weak mid/upper lapse rates, the northward return of seasonably moist
boundary layer air (including surface dew points near 70F), coupled
with boundary layer warming, is also contributing to modest
destabilization across this region. Mixed-layer CAPE probably will
continue to increase through the 500-1000+ J/kg range into mid to
late afternoon, perhaps as far north as south central Pennsylvania.

The primary increase in severe weather potential to the east of the
Allegheny Mountains still appears likely to occur in association
with an intensifying squall line near/just ahead of an approaching
strengthening cold front, mainly during and after the 21-23Z time
frame. However, it might not be out of the question that the
ongoing destabilization, weakening inhibition, and perhaps forcing
for ascent associated with weak warm advection, may become
sufficient to support isolated to widely scattered discrete
convective development in advance of the front. If this occurs, the
environment will probably be conducive to supercells, which may be
accompanied by the risk for tornadoes, in addition to localized
strong surface gusts.

..Kerr/Grams.. 10/31/2019
 
mcd2130.gif

Mesoscale Discussion 2130
NWS Storm Prediction Center Norman OK
1225 PM CDT Thu Oct 31 2019

Areas affected...Portions of central eastern Georgia...far western
South Carolina

Concerning...Severe potential...Watch possible

Valid 311725Z - 311930Z

Probability of Watch Issuance...40 percent

SUMMARY...Low-topped showers and embedded thunderstorms will
continue east/northeast this afternoon and evening. Damaging wind
gusts will be the primary threat with some potential for brief,
isolated tornado or two. Threat should subside after 00Z as
shortwave trough and associated lift departs to the northeast.

DISCUSSION...A line of showers and embedded thunderstorms has
developed along and ahead of an approaching cold front in western
Georgia. With modest surface heating of a moist (low 70s F
dewpoints) airmass ahead of this activity, storms will move into an
environment with 1000-1500 J/kg MLCAPE. While mid-level ascent is
approaching from the west, this forcing will maximize from around
20-00Z. Thereafter, the shortwave trough will lift to the northeast.
During that time frame, storm intensity is likely to increase due to
the favorable effective shear (40-50 kts) as well as favorable
overlap of upper-level forcing and buoyancy. Given the strong
low/mid-level wind fields, damaging convective wind gusts will be
possible. Low-level flow is quite veered in this region. With that
said, moderate to strong 850 mb winds will continue into the evening
and support some potential for low-level storm rotation. Brief,
isolated tornado or two will also be possible.

..Wendt/Grams.. 10/31/2019
 
You must log in or register to reply here.
Back
Top