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Severe March 1st Severe Weather Threat

metwannabe said:
Webber, SD for most of us east of the Apps the tor threat should be extremely low correct (maybe a quick spin up along the line) but if any discrete cells can pop out front of that line environment appears a little more favorable for a possible tor.... am I correct in what I'm seeing? Thanks
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I would say so. I doubt we get much development ahead of the line and most of the tor threat would be the QLCS spinups. Just my thoughts though
 
SD said:
I would say so. I doubt we get much development ahead of the line and most of the tor threat would be the QLCS spinups. Just my thoughts though
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Which is a good thing.... clouds gonna temper our chances today but still should be a good wind threat tonight
 
Bulk shear at 60-70kts definitely enough for Wake County by 9pm on the HRRR but it looks like the timing is going to suck, we'll be limited by night..not saying a tornado can't happen at night of course, just move this up 4 hours earlier and we'd be at a higher risk I'm sure. To me there's no indication at all for discrete cells or any development ahead of the line...so if there's a tor it's going to be an embedded, rain wrapped mess. We also won't get the wind TN and to the west will. Despite the HRRR soundings I'll have to see the daily trends to bite.
 
Yeah this is mainly a wind damage threat anyway, even if we had adequate destabilization. An isolated tornado embedded within a bookend vortex or near a bowing segment is still possible, and there probably will end up being 1-2 somewhere east of the apps.
 
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60kt 850mb winds with some 70kt winds along the NC/VA border....wind damage incoming this evening
 
Looks like an active day. Hate I can't keep up with things at work like I used to. Going to try to check in every once and a while, especially since it look like we're on the border here for some good storms and wind.
 
Tornado watch likely forthcoming for parts of northern Alabama, north-central Mississippi, and northwestern GA
Mesoscale Discussion 0241
NWS Storm Prediction Center Norman OK
1008 AM CST Wed Mar 01 2017

Areas affected...Northern/central MS...southern middle/eastern
TN...northern/central AL...and northwestern GA

Concerning...Severe potential...Tornado Watch likely

Valid 011608Z - 011815Z

Probability of Watch Issuance...80 percent

SUMMARY...An increasing severe threat is expected over the next
several hours, with all severe hazards possible, including a few
tornadoes. New tornado watch issuance is likely by 18Z.

DISCUSSION...Mid-level southwesterly flow along a cold front in
middle/western TN has slowed the southeastward movement of the
front. A line of convection along/just ahead of the front has
displayed some strong to damaging wind threat over the past several
hours. The airmass across northern MS/AL ahead of the will continue
to destabilize through the afternoon even with partly to mostly
cloudy skies present. Steep mid-level lapse rates with an elevated
mixed layer are present on the 12Z Jackson, MS sounding and
sufficient low-level moisture across the area will support MLCAPE of
500-1000 J/kg this afternoon. 50-60 kt of effective bulk shear will
support supercell structures both within and ahead of the line,
particularly across northern MS into northern/central AL where
semi-discrete convection is already developing as of 16Z. Although
low-level flow is veered generally to southwesterly, sufficient
curvature in the 0-3 km layer will support effective SRH around
250-300 m2/s2, which suggests at least some tornado threat will
likely develop. Large hail will able be possible with the initial
discrete convection, with damaging winds becoming more probable with
time as thunderstorms congeal into a line.

..Gleason/Hart.. 03/01/2017


ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MEG...JAN...

LAT...LON 33048725 32588875 32449003 32409092 32899121 33579106
34419052 34818974 35428794 35648655 35508550 35258414
34708403 33948531 33048725

mcd0241.gif
 
Wow, seems like the threat has really ramped up for my area. I was not expecting this
 
FFC:
SPOTTER INFORMATION STATEMENT...

Spotter aactivation will likely be necessary across much of north and
central Georgia, especially after 2 PM this afternoon, through this
evening.
 
Yea the timing is virtually unchanged in NW Georgia, the storms will be coming through near peak heating, but yea a few isolated, discrete super cells forming out ahead of the main QLCS/squall line is definitely likely... Surface based CAPE and relative helicity is impressive over northeastern AL and northwestern GA.

Here's a link from a research page one of our PhD students and Dr. Parker run regarding high shear, low CAPE environments here in the southeastern US... You can get real time plots of their SHERB parameters from various models. Basically, without going into too much detail, when the SHERB parameters are equal to or over 1, significant severe defined as..."* ... tornadoes rated EF2 or higher, wind reports of 65 knots or higher, and hail reports of 2" diameter or larger" are more probable-likely
https://www.meas.ncsu.edu/mdparker/sherb/

Here's SHERB from the RAP for NC as the squall line is getting into central-eastern NC. Not too shabby w/ values ~ 1.3
shrbtiles.06.gif
 
New Tornado Watch:

ww0057_overview_wou.gif


URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 57
NWS Storm Prediction Center Norman OK
1150 AM CST Wed Mar 1 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Northern and Central Alabama
Northern Georgia
Central and Northeast Mississippi
Extreme Western North Carolina
Southeast Tennessee

* Effective this Wednesday morning and evening from 1150 AM until
600 PM CST.

* Primary threats include...
A few tornadoes likely
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible

SUMMARY...Thunderstorms will slowly intensify this afternoon along a
boundary extending from northern MS into southeast TN, and spread
across the watch area. Large hail and isolated tornadoes are the
main threats with these storms.

The tornado watch area is approximately along and 60 statute miles
north and south of a line from 40 miles southwest of Greenwood MS to
65 miles east of Chattanooga TN. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU7).
 
New Tornado Watch until 6:00pm for AL

TORNADO WATCH OUTLINE UPDATE FOR WT 57
NWS STORM PREDICTION CENTER NORMAN OK
1150 AM CST WED MAR 1 2017

TORNADO WATCH 57 IS IN EFFECT UNTIL 600 PM CST FOR THE
FOLLOWING LOCATIONS

ALC009-015-019-033-043-049-055-057-059-063-071-073-075-077-079-
083-089-093-095-103-107-115-119-125-127-133-020000-
/O.NEW.KWNS.TO.A.0057.170301T1750Z-170302T0000Z/

AL
. ALABAMA COUNTIES INCLUDED ARE

BLOUNT CALHOUN CHEROKEE
COLBERT CULLMAN DEKALB
ETOWAH FAYETTE FRANKLIN
GREENE JACKSON JEFFERSON
LAMAR LAUDERDALE LAWRENCE
LIMESTONE MADISON MARION
MARSHALL MORGAN PICKENS
ST. CLAIR SUMTER TUSCALOOSA
WALKER WINSTON
 
HRRR is impressive for late this afternoon for central AL. It gets SBCapes close to 2000 with good wind fields. Tornado risk is still low. The analogs on PW did show some good hail events though.
 
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Mesoscale Discussion 0243
NWS Storm Prediction Center Norman OK
1150 AM CST Wed Mar 01 2017

Areas affected...Northern NC...eastern VA...the Delmarva
Peninsula...NJ...and southeastern PA

Concerning...Severe potential...Watch likely

Valid 011750Z - 011845Z

Probability of Watch Issuance...80 percent

SUMMARY...A damaging wind and isolated tornado threat will increase
with a line of storms approaching from the west. Watch issuance is
likely.

DISCUSSION...An ongoing line of showers and thunderstorms across
central/western VA is quickly advancing eastward. As it does so,
this line should strengthen as it encounters an increasingly moist
and unstable airmass. Diurnal heating has allowed temperatures to
warm into the upper 60s to upper 70s as of 1745Z, with surface
dewpoints generally in the mid 50s to lower 60s. The instability
should build northward with time across NJ. 15Z sounding from GSO
and 16Z sounding from RNK both reveal steep mid-level lapse rates
around 8 degrees C/km that will support weak to moderate instability
across this area through the afternoon. Widespread damaging winds
appear likely as the convective line restrengthens. In addition, RAP
forecast soundings show enlarged low-level hodographs across the
eastern VA into Delmarva Peninsula and southern/central NJ, as winds
veer from generally southerly to southwesterly with height while
also strengthening. This should support an isolated tornado threat
with embedded circulations within the line.
 
Halifax-Northampton Regional Airport (my local airport) already recorded wind gust of 46 mph today, very strong winds out front of the line... also some reports of power outages in Va border counties.
 
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Mesoscale Discussion 0244
NWS Storm Prediction Center Norman OK
0107 PM CST Wed Mar 01 2017

Areas affected...Portions of western NC...western SC...far northeast
GA

Concerning...Severe potential...Watch likely

Valid 011907Z - 012100Z

Probability of Watch Issuance...80 percent

SUMMARY...A risk for severe storms will spread across portions of
the southern Appalachians and adjacent Piedmont region, affecting
the area around and after 20Z. Watch issuance will be likely.

DISCUSSION...A squall line with embedded rotating updrafts from
eastern TN to north MS will continue spreading eastward through the
afternoon. Diurnal heating of a modestly moist boundary layer is
supporting MLCAPE around 250-750 J/kg ahead of this activity. With
strong deep shear, organized convective structures including
occasional bowing segments will spread across the region. This
activity will be capable of producing damaging wind gusts. A brief
tornado or two cannot be ruled out with line-embedded meso-vortices.
Watch issuance will be likely within the next hour or so.
 
ForsythSnow said:
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SPC really upped the tornado risk for our area.
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Kind of surprised to see an increased risk down this way since I thought the main tornado threat was further north. As long as the storms stay in a line and don't separate into individual super cells we may just have a wind and hail threat.
 
New watch out. Wake isn't in it. But everyone west of Wake is.
 
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