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Severe March 1st Severe Weather Threat

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inflow notches in the line on the HRRR for us NC folks?


Sent from my iPhone using Tapatalk
 
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:
day1probotlk_1630_torn.gif
SPC really upped the tornado risk for our area.
Click to expand...
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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