2015 Severe Weather Thread

[Brick Tamland]

[downeastnc]

They did....only to reissue it once it got near fairfield co      The southern rotation (near redbank) was 3 miles to my northwest     I did get a small wind gust as the line passed threw     My firefighter friends in Calhoun Co are on a call Sunny Plains(close to hwy 21) where 3 houses (together) have some damage and there is a family trapped in one of them. They are saying possible tornado, but I don't remember seeing any rotation to my southwest while I was checking out the storms

 

There was a small tight couplet for 2-3 frames about 20 miles or so SE of the Columbia radar location right around 5:30......not sure of that area or if that would be close to where the damage was....

[Solak]

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 82 CONTINUES.

   SUMMARY...OVERALL SEVERE RISK SHOULD CONTINUE TO DIMINISH WITH
   DOWNSTREAM WW ISSUANCE UNLIKELY. BUT LOW THREATS FOR DAMAGING WINDS
   AND A BRIEF TORNADO MAY PERSIST THROUGH THE REST OF THE EVENING
   WITHIN WW 82 AND ELSEWHERE IN ERN NC.

   DISCUSSION...OVERALL OBSERVATIONAL TRENDS DEPICT A WEAKENING
   REFLECTIVITY GRADIENT...DIMINISHING LIGHTNING...AND IR CLOUD TOP
   WARMING DURING THE PAST HOUR...INDICATIVE OF AN INCREASINGLY SHALLOW
   QLCS FROM ORANGE TO BLADEN COUNTIES. 00Z MHX/GSO RAOBS SAMPLED POOR
   TROPOSPHERIC LAPSE RATES WITH ONLY MEAGER BUOYANCY DESPITE PW VALUES
   AROUND 1.75 INCHES. 0-1 KM SHEAR HAS REMAINED AROUND 25 KT WHICH
   COULD STILL SUPPORT A NON-ZERO RISK FOR A BRIEF TORNADO AND
   LOCALIZED DAMAGING WINDS. BUT GIVEN THE OBSERVATIONAL TRENDS AND
   DEARTH OF INSTABILITY IN RAOBS...THESE RISKS APPEAR MARGINAL.
 

[lj0109]

They did....only to reissue it once it got near fairfield co      The southern rotation (near redbank) was 3 miles to my northwest     I did get a small wind gust as the line passed threw     My firefighter friends in Calhoun Co are on a call Sunny Plains(close to hwy 21) where 3 houses (together) have some damage and there is a family trapped in one of them. They are saying possible tornado, but I don't remember seeing any rotation to my southwest while I was checking out the storms

 

Buckeye and Downeast, here is a screenshot I grabbed of that couplet that popped up in the western portion of Calhoun County and would have indeed gone through the Sunny Plains area.  Here it is crossing US21 and eventually I-26 north of the SC Hwy 6 Exit (MM136):

[buckeyefan1]

There was a small tight couplet for 2-3 frames about 20 miles or so SE of the Columbia radar location right around 5:30......not sure of that area or if that would be close to where the damage was....

That area is just a couple of miles to my southeast   

 

Buckeye and Downeast, here is a screenshot I grabbed of that couplet that popped up in the western portion of Calhoun County and would have indeed gone through the Sunny Plains area.  Here it is crossing US21 and eventually I-26 north of the SC Hwy 6 Exit (MM136):

 

Sweet capture! MM136  has some damage there too at Alaglas     

[Shawn]

Well for those around Columbia, Lexington, & Lake Murray.  There was a tornado because I accidentally drove into it.  Details..

 

There was a cell coming out of Edgefield and another bigger cell coming out of Aiken.  The Edgefield cell became the bigger one for a bit while the Aiken cell lost most of it's rotation.  Over the next half-hour or so, the two cells which were a good ways apart from each other kept strengthening and weakening.  They both died out.

 

About 15 minutes later, as the cells approached Highway 378 in Lexington (the Edgefield cell was on the way Western side cutting up the western part of Lake Murray) and the Aiken cell (with no visible rotation on radar) headed right to my Southeast.  I was outside my house in a truck watching all the rotation head to my Northeast across the woods (the funnel was trying to hard to get it's act together to the ground).  I thought that was it.

 

Turns out, right to the South a new area of rotation turned up and it was doing a horizonal/slanted path across highway 378 which is 2 miles from my house... from radar imagery.. so I was like "well, I'll go this way and try to get a glimpse of it"... yeah that wasn't a good idea.  My radar data was outdated on my phone... and I drove into the damn thing not 1,000 foot from my driveway.  I just stopped in the middle of the road and said "****" and it grazed me.. and I headed to a side road and just parked and watched a couple trees and limbs tumble on down.

 

Thank God it was weak, but overall barely any damage.. and the rain made seeing anything of it (until it was in my face) impossible.  It was weird though, I relate the experience of it to a microburst type event... but by the time I got back in, it was a pretty okay NROT signature over the lake heading towards Irmo.  But WHEW!

 

The last event I was basically in was when some Twisters hit Lexington and I happened to be in Kroger that day when the bigger one was tearing the whole area up.  I was too young to understand and all.  August 16, 1994 was the day.  So overall, I was excited to see what I did today, but also felt like an idiot for trusting any radar data at face value so close to my house and trying to drive towards it at all.  Especially with the amount of heavy rain (rainwrapped) situation going on.

 

So overall there were about 4 or 5 cells that were producing brief funnels/weak tors in the line from the Edgefield/Saluda area, all the way across to the East of Orangeburg and North.   As the air became more unstable in the South Central midlands (which was expected), things really ramped up as they blew on through... and made it a bit further North than originally anticipated.  This area was right on the edge of the Meso discussion when it was first issued before the Tor Watch.

[Hvward]

Nice line of showers moving through WNC right now. To my south where the mountains aren't impeding flow those cells look stout. They are also moving into a better environment with better helicity and a bit more cape so this could be something to watch. Wish I wasn't working today and could chase but the real world sucks.

[No snow for you]

Very heavy cells moving into Greenville now. If this line holds, watch out Charlotte. 

[downeastnc]

Nice line of showers moving through WNC right now. To my south where the mountains aren't impeding flow those cells look stout. They are also moving into a better environment with better helicity and a bit more cape so this could be something to watch. Wish I wasn't working today and could chase but the real world sucks.

 

This is my issue as well, working till 7:30, but these setups are hard to chase just ask Shawn lol.....though its appears more discrete this morning and maybe we will get some true supercells versus that QLCS type mess we saw in SC yesterday,

[ILMRoss]

First chase of the year for me today! I'm absolutely enthralled. Should be fun if we actually get anything to develop. Anybody else going out today?

[Cold Rain]

RAH still uncertain on the amount of convection this afternoon across the Piedmont. Pretty good discussion from Vincent:

PRECIPITATION: THE RECENT INCREASE IN CONVECTIVE INTENSITY OVER THE

COASTAL PLAIN IS ASSOCIATED WITH ENHANCED LOW-LEVEL CONVERGENCE

/BACKED LOW-LEVEL FLOW/ AND THE ADVECTION OF A HIGHER THETA-E

AIRMASS INTO EASTERN NC...APPARENTLY IN RESPONSE TO DPVA ATTENDANT

THE NEGATIVELY TILTED SHORTWAVE CURRENTLY TRACKING NE ACROSS THE

REGION. NOW THAT THIS ACTIVITY HAS EXITED CENTRAL NC...EXPECT DRY

CONDITIONS TO PREVAIL THROUGH SUNRISE IN ASSOC/W SUBSIDENCE IN THE

WAKE OF THE AFOREMENTIONED SHORTWAVE AND...FOR THE REMAINDER OF THE

MORNING...A LACK OF FORCING DRYING ALOFT COMBINED WITH DRYING ALOFT

ASSOC/W THE ADVECTION OF A MODIFIED ELEVATED MIXED LAYER INTO THE

REGION FROM THE SOUTHWEST. UNCERTAINTY INCREASES BY EARLY AFTERNOON

REGARD TO WHETHER OR NOT THE ONGOING TN VALLEY MCS WILL CROSS THE

SOUTHERN APPALACHIANS AND RESULT IN A POTENTIAL FOR CONVECTION IN

THE FAR WESTERN PIEDMONT BETWEEN 15-18Z. THE LATEST HIGH-RES CAMS

SUGGEST THAT THE MCS WILL DECAY ON APPROACH TO THE MOUNTAINS ~12Z AS

THE THERMODYNAMIC ENVIRONMENT BECOMES LESS FAVORABLE (I.E.

INCREASING CINH). EVEN IF THE MCS DECAYS PRIOR TO CROSSING THE

MOUNTAINS...THE PRESENCE OF AN MCV AND/OR LINGERING CONVECTIVE

DEBRIS/OUTFLOW WOULD INTRODUCE CONSIDERABLE UNCERTAINTY TO THE

CONVECTIVE FORECAST THIS AFTERNOON. EVEN IF ONE ASSUMES THE

AFOREMENTIONED FEATURES ARE ABSENT...THE CONVECTIVE FORECAST REMAINS

UNCERTAIN GIVEN A TEMPORAL/SPATIAL DISCONNECT BETWEEN THE BEST

SYNOPTIC FORCING (DPVA IN SW FLOW ALOFT BETWEEN 00-06Z)...THE BEST

LOW-LEVEL FOCUS (PRE-FRONTAL TROUGH IN THE WESTERN PIEDMONT BY

~00Z)...AND PEAK HEATING. WITH THE ABOVE IN MIND...WILL MAKE LITTLE

CHANGE TO THE PRIOR FORECAST AND INDICATE PRECIP CHANCES OF 40-50%

DURING THE LATE AFTERNOON AND EVENING...ENDING FROM WEST-EAST BY OR

SHORTLY AFTER MIDNIGHT.

SEVERE THREAT: MODERATE DESTABILIZATION (MLCAPE 1000-2000 J/KG) IS

EXPECTED TODAY IN ASSOC/W CLEARING SKIES...A MODIFIED ELEVATED MIXED

LAYER (CHARACTERIZED BY H7-H5 LAPSE RATES ON THE ORDER OF 6.5-7

C/KM)...AND SEASONABLY RICH LOW-LEVEL MOISTURE (DWPTS UPPER

50S/LOWER 60S) WITHIN AN INCREASINGLY WELL-MIXED WARM SECTOR

DOWNSTREAM OF THE APPROACHING COLD FRONT...WITH LITTLE IN THE WAY OF

A CAP /CINH/ PER LATEST FORECAST SOUNDINGS. ANY UPDRAFTS THAT

DEVELOP PRIOR TO ~21Z THIS AFTERNOON ARE UNLIKELY TO SURVIVE

ENTRAINMENT GIVEN A DRY AIRMASS ALOFT AND A GENERAL LACK OF FORCING

THROUGHOUT THE COLUMN...ASSUMING NO CONTRIBUTION FROM UPSTREAM

CONVECTION. BY LATE AFTERNOON...MODERATE/UNTAPPED INSTABILITY AND AN

ABSENCE OF CONVECTIVE INHIBITION ARE EXPECTED TO ALLOW CONVECTIVE

DEVELOPMENT ALONG THE COLD FRONT /PRE-FRONTAL TROUGH/ PROGRESSING

INTO THE FOOTHILLS...WITH UNIDIRECTIONAL DEEP-LAYER SHEAR SUFFICIENT

FOR SPLITTING SUPERCELLS AND UPSCALE GROWTH INTO A LINEAR MCS

THEREAFTER...THOUGH THE LATEST CONVECTION ALLOWING MODELS SUGGEST

MULTIPLE LINE SEGMENTS MAY DEVELOP RATHER THAN A SOLID LINE...WHICH

SEEMS REASONABLE GIVEN THE UNCERTAINTIES MENTIONED ABOVE. SHOULD

SPLITTING SUPERCELLS DEVELOP IN THE WESTERN PIEDMONT...LARGE HAIL

(UP TO GOLFBALL SIZE) AND DAMAGING WINDS WOULD BE POSSIBLE GIVEN

SPEEDY MID-LEVEL FLOW...MDT INSTABILITY AND STEEP MID-LEVEL LAPSE

RATES. FURTHER EAST...DAMAGING WINDS WOULD BE THE PRIMARY THREAT...

WITH SEVERE HAIL CONFINED TO ROTATING UPDRAFTS EMBEDDED WITHIN LINE

SEGMENTS. -VINCENT

[Hvward]

This is my issue as well, working till 7:30, but these setups are hard to chase just ask Shawn lol.....though its appears more discrete this morning and maybe we will get some true supercells versus that QLCS type mess we saw in SC yesterday,

Yeah man yesterday was a bust of a chase day.. Got just west of Columbia as the line lost rotation. Had considered the AL/GA line play but chose GA/SC instead. Hopefully a few descrete's get going out in open fields for those who are chasing today. Still not sure if the atmosphere will produce, but unless you're Shawn you got to be in good position to see these. Rain wrapped for sure.

[Brick Tamland]

The enhanced portion is not far away.

 

 

[downeastnc]

Its all about the sun and how much recovery the atmosphere can get I would think chances for severe will be high the further east you go but to far east and the timing might cause you issues as the front gets in too late...

[Brick Tamland]

Sun is out here. Looks like the clouds are breaking.

[downeastnc]

Sun peeking out here as well, so if we can get 5-7 hrs of decent sun and then get the front in here between 5-8 then there could be some decent storms I would also watch Charlotte up to the Triad there is some sun out in front of that nasty little line segment working east this morning....but that appears to be a weak left over MCV and is not to be confused with the main event which should fire later in the day

[Hvward]

Sun peeking out here as well, so if we can get 5-7 hrs of decent sun and then get the front in here between 5-8 then there could be some decent storms I would also watch Charlotte up to the Triad there is some sun out in front of that nasty little line segment working east this morning....but that appears to be a weak left over MCV and is not to be confused with the main event which should fire later in the day

Yeah agreed, didn't mean to confuse anyone if I did with my earlier posts. With the sun out, that is a good sign for anyone who wants severe. Hopefully it will stay out but that MCV is just a little tease.

[Solak]

Whole lot of 'ifs' in the RAH update...

 

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 1015 AM MONDAY...

UPDATE: MOST IMMEDIATE CONCERN IS THE CONVECTIVE COMPLEX WHICH
CROSSED TN OVERNIGHT AND MAINTAINED STRENGTH CROSSING THE FAR SRN
APPALACHIANS. BAND OF STRONG TO SEVERE STORMS WITH BOWING SEGMENTS
IS PROGRESSING QUICKLY EASTWARD AND WILL ARRIVE IN OUR SW COUNTIES
WITHIN THE NEXT 30 MIN. CLT TDWR INDICATES WINDS OVER 45 MPH ARE
LIKELY... AND THE OB SITE AT SHELBY REPORTED 46 MPH JUST UNDER AN
HOUR AGO. UNFORTUNATELY NONE OF THE CONVECTION-ALLOWING MODELS
PICKED UP ON THIS LONG-LIVED SYSTEM VERY WELL... INCLUDING THE HRRR
WHICH CONTINUES TO SHOW THE BAND DYING WITH LITTLE TO NOTHING ON ITS
SOUTHERN FLANK. THIS LINE SHOULD CONTINUE TO PRESS TO THE ENE FOR
THE FORESEEABLE FUTURE WITH DYNAMIC SUPPORT VIA DPVA ALOFT AND GOOD
UPPER DIVERGENCE IN THE LEFT FRONT QUAD OF THE STJ. CLOUDS EAST OF
THIS LINE HAVE LARGELY DISSIPATED... ALLOWING EARLY-DAY HEATING TO
FURTHER DESTABILIZE A COLUMN THAT HAS ALREADY (ACCORDING TO SPC
MESOANALYSIS) ATTAINED AN MUCAPE NEAR 500 J/KG (ALBEIT WITH SOME
REMAINING CINH)... AND INCOMING EFFECTIVE SHEAR OF 40-45 KTS IS
SUFFICIENT TO MAINTAIN THIS CONVECTION. IF THIS INDEED HOLDS
TOGETHER AND FEEDS ON THE EXISTING INSTABILITY... ANY TRAILING
SUBSIDENCE WOULD LIMIT ADDITIONAL CONVECTION THIS AFTERNOON.
HOWEVER... WE'RE ALREADY SEEING INSTABILITY REBOUND OVER CENTRAL AL
INTO NRN GA... AND THE 00Z WRF NMM/ARW DEPICTED A BROKEN BAND OF
CONVECTION FORMING JUST EAST OF HERE AND PROGRESSING ENE THROUGH
CENTRAL NC LATE AFTERNOON AND EARLY EVENING (ALTHOUGH THEY DID NOT
DEPICT THE CURRENT COMPLEX SURVIVING THIS LONG AT ALL). SO MANY
QUESTIONS REMAIN REGARDING TIMING. WILL STAY WITH THE SCENARIO OF
THIS CURRENT CONVECTION HOLDING TOGETHER AS A WAVY BAND WITH
STRAIGHT LINE WIND GUSTS... THEN STILL EXPECT ANOTHER ROUND OF
STORMS LATE THIS AFTERNOON THROUGH MID EVENING... AND GUSTY WINDS
AND LARGE HAIL WILL STILL BE POSSIBLE WITH THESE IF WE CAN ACHIEVE
ENOUGH REBOUND INSTABILITY AHEAD OF THE COLD FRONT. -GIH

[downeastnc]

Whole lot of 'ifs' in the RAH update...

 

.NEAR TERM /TODAY AND TONIGHT/...

AS OF 1015 AM MONDAY...

UPDATE: MOST IMMEDIATE CONCERN IS THE CONVECTIVE COMPLEX WHICH

CROSSED TN OVERNIGHT AND MAINTAINED STRENGTH CROSSING THE FAR SRN

APPALACHIANS. BAND OF STRONG TO SEVERE STORMS WITH BOWING SEGMENTS

IS PROGRESSING QUICKLY EASTWARD AND WILL ARRIVE IN OUR SW COUNTIES

WITHIN THE NEXT 30 MIN. CLT TDWR INDICATES WINDS OVER 45 MPH ARE

LIKELY... AND THE OB SITE AT SHELBY REPORTED 46 MPH JUST UNDER AN

HOUR AGO. UNFORTUNATELY NONE OF THE CONVECTION-ALLOWING MODELS

PICKED UP ON THIS LONG-LIVED SYSTEM VERY WELL... INCLUDING THE HRRR

WHICH CONTINUES TO SHOW THE BAND DYING WITH LITTLE TO NOTHING ON ITS

SOUTHERN FLANK. THIS LINE SHOULD CONTINUE TO PRESS TO THE ENE FOR

THE FORESEEABLE FUTURE WITH DYNAMIC SUPPORT VIA DPVA ALOFT AND GOOD

UPPER DIVERGENCE IN THE LEFT FRONT QUAD OF THE STJ. CLOUDS EAST OF

THIS LINE HAVE LARGELY DISSIPATED... ALLOWING EARLY-DAY HEATING TO

FURTHER DESTABILIZE A COLUMN THAT HAS ALREADY (ACCORDING TO SPC

MESOANALYSIS) ATTAINED AN MUCAPE NEAR 500 J/KG (ALBEIT WITH SOME

REMAINING CINH)... AND INCOMING EFFECTIVE SHEAR OF 40-45 KTS IS

SUFFICIENT TO MAINTAIN THIS CONVECTION. IF THIS INDEED HOLDS

TOGETHER AND FEEDS ON THE EXISTING INSTABILITY... ANY TRAILING

SUBSIDENCE WOULD LIMIT ADDITIONAL CONVECTION THIS AFTERNOON.

HOWEVER... WE'RE ALREADY SEEING INSTABILITY REBOUND OVER CENTRAL AL

INTO NRN GA... AND THE 00Z WRF NMM/ARW DEPICTED A BROKEN BAND OF

CONVECTION FORMING JUST EAST OF HERE AND PROGRESSING ENE THROUGH

CENTRAL NC LATE AFTERNOON AND EARLY EVENING (ALTHOUGH THEY DID NOT

DEPICT THE CURRENT COMPLEX SURVIVING THIS LONG AT ALL). SO MANY

QUESTIONS REMAIN REGARDING TIMING. WILL STAY WITH THE SCENARIO OF

THIS CURRENT CONVECTION HOLDING TOGETHER AS A WAVY BAND WITH

STRAIGHT LINE WIND GUSTS... THEN STILL EXPECT ANOTHER ROUND OF

STORMS LATE THIS AFTERNOON THROUGH MID EVENING... AND GUSTY WINDS

AND LARGE HAIL WILL STILL BE POSSIBLE WITH THESE IF WE CAN ACHIEVE

ENOUGH REBOUND INSTABILITY AHEAD OF THE COLD FRONT. -GIH

 

Yeah they were kinda gung ho last week and we got nada so there seems to be a bit more CYA in this disco than usual....timing and mid level drying seem to be a issue and for what it is worth MHX basically wrote it off

 

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...

AS OF 430 AM MONDAY...THE FRONT WILL CROSS THE AREA EARLY

TUESDAY. THE CHALLENGE WILL BE THE EXTENT OF PRECIPITATION AHEAD

OF THE FRONT AND IF STORMS WILL DEVELOP/MOVE INTO THE AREA. GIVEN

THE TIMING OF THE FRONT...FEEL THE CHANCE OF THUNDERSTORMS WILL BE

LIMITED AS PEAK HEATING WILL HAVE ALREADY OCCURRED.

FURTHERMORE...THE BEST SYNOPTIC FORCING...SFC FRONT AND PEAK

HEATING WILL NOT COEXIST GIVING THIS SCENARIO A LOW CONFIDENCE

LEVEL IN TERMS OF THUNDERSTORM DEVELOPMENT AND SUBSTAINABILITY.

GIVEN MARGINAL LIFT...INSTABILITY AND SHEAR...WE CAN NOT RULE OUT

DISCRETE THUNDERSTORMS POSSIBLY BECOMING LINEAR IN NATURE DURING

THE EVENING HOURS...BUT THE OVERALL SPATIAL EXTENT LOOKS MINIMAL.

BY THE TIME THE MID-LEVEL DRY AIR BECOMES BETTER

SATURATED...INSTABILITY WILL HAVE DIMINISH QUITE A BIT. IF THE

FRONT MOVES A BIT FASTER THAN ANTICIPATED OR THERE IS BETTER

LIFT/SATURATION AHEAD OF THE FRONT...THEN THERE MAY BE BETTER

SPATIAL COVERAGE OF THUNDERSTORMS. AT THIS TIME...WE FEEL ANY

ACTIVITY WILL WANE AS IT CROSSES EASTERN NC DURING THE EVENING

HOURS. KEPT A CHANCE POP IN FOR THE TIME BEING.

[Brick Tamland]

Whole lot of 'ifs' in the RAH update...

 

 

 

Goes along with all the uncertainties they had earlier. Also said the models didn't show the current strong storms already happening.

[Brick Tamland]

Yeah they were kinda gung ho last week and we got nada so there seems to be a bit more CYA in this disco than usual....timing and mid level drying seem to be a issue and for what it is worth MHX basically wrote it off

 

 

 

The severe storm discussions are starting to sound like the winter storm discussions around here.

[metalicwx366]

Under a severe thunderstorm watch here. Been cloudy and drizzle all day. Haven't even been paying attention to today's threat.

[Solak]

Well, there aren't any more strong storms.... that convection is barely a few showers now and diminishing even further. Noticed they've dropped our expected high for the day from 83 to 79. A few storms starting to pop in N. GA which could migrate into the Carolinas this afternoon/evening.

[mackerel_sky]

The line that came through this morning was like a mini derecho! Lots of reports of tree damage and very strong , roaring winds. Missed just to my North

[Brick Tamland]

SPC expanded the enhanced threat area further southwest.

 

[lj0109]

 

@NWSColumbia

EF-1 Tornado damage from Sunday night storm confirmed by NWS along Sunny Plain Road in Calhoun County.

Just saw this note from CAE

[kevinbente]

well, if stuff looks interesting after my atmospheric instrumentation class i could drive north to FLL to see if any mischief could arise.

[Solak]

Disco to go with Brick's updated map...

 

   ...NC/SC...
   12Z CAM SOLUTIONS CONTINUE TO SUPPORT THE DEVELOPMENT OF A LINE OF
   THUNDERSTORMS THIS AFTERNOON FROM WESTERN NC INTO UPSTATE SC.  THESE
   STORMS WILL TRACK EASTWARD ACROSS MUCH OF NC DURING THE AFTERNOON
   AND EVENING...POSING A RISK OF DAMAGING WINDS AND HAIL.

   ...FL/GA...
   SCATTERED THUNDERSTORMS ARE CURRENTLY AFFECTING PARTS OF NORTH FL.
   OTHER MORE INTENSE CONVECTION IS EXPECTED TO DEVELOP BY MID
   AFTERNOON OTHER THE NORTHERN AND EASTERN FL PENINSULA AS DAYTIME
   HEATING LIFT AHEAD OF AN APPROACHING UPPER SYSTEM HELP TO
   DESTABILIZE THE AIR MASS.  STRONG TO SEVERE STORMS MAY OCCUR OVER
   THIS REGION WITH HAIL AND WIND POSSIBLE.  REFER OF MCD NUMBER 395
   FOR FURTHER DETAILS.

   ...SOUTHEAST AL/SOUTHWEST GA...
   WILL MAINTAIN LOW SEVERE PROBABILITIES FOR PARTS OF EASTERN
   AL/WESTERN GA WHERE ISOLATED STRONG THUNDERSTORMS MAY FORM ALONG THE
   COLD FRONT LATER TODAY.  WIDESPREAD CLOUDS CURRENTLY IN THIS AREA
   LIMIT CONFIDENCE IN A GREATER SEVERE THREAT.

[Brick Tamland]

SPC seems to think the threat for here is increasing, while RAH is still unsure.

[Brick Tamland]

 

MESOSCALE DISCUSSION 0396
   NWS STORM PREDICTION CENTER NORMAN OK
   1203 PM CDT MON APR 20 2015

   AREAS AFFECTED...FAR NE GA...UPSTATE SC...PORTIONS OF WRN AND
   CENTRAL NC

   CONCERNING...SEVERE POTENTIAL...WATCH NEEDED SOON

   VALID 201703Z - 201800Z

   PROBABILITY OF WATCH ISSUANCE...95 PERCENT

   SUMMARY...SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO
   DEVELOP ACROSS PORTIONS OF UPSTATE SC INTO WESTERN AND CENTRAL NC.
   HAIL AND STRONG WINDS WILL BE THE MAIN THREAT BUT A TORNADO CAN NOT
   BE RULED OUT. A WATCH WILL LIKELY BE NEED SOON.

   DISCUSSION...ISOLATED THUNDERSTORMS WERE DEVELOPING OVER NORTHEAST
   GA AHEAD OF THE SURFACE COLD FRONT. WHILE INITIAL STORMS MAY PRODUCE
   SOME GUSTY WINDS OR SMALL HAIL...THE GREATER THREAT FOR SEVERE
   WEATHER WILL BE FURTHER DOWNSTREAM ACROSS PARTS OF UPSTATE SC INTO
   WESTERN AND CENTRAL NC. HERE...TEMPERATURES HAVE WARMED INTO THE 70S
   WITH SOME AREAS NEAR 80 DEGREES EARLY THIS AFTERNOON. WHILE SOME
   HIGH CLOUDS ARE MOVING OVER THE REGION...SUFFICIENT INSTABILITY
   EXISTS WITH MESOANALYSIS INDICATING A NEARLY UNCAPPED ENVIRONMENT.
   AS EVIDENCE OF THIS...CU DEVELOPMENT WAS NOTED IN LATEST VIS
   SATELLITE IMAGERY FROM NEAR THE SC/NC BORDER INTO CENTRAL NC. STRONG
   DEEP LAYER SHEAR WILL SUPPORT SUPERCELL STRUCTURES THAT COULD REMAIN
   SEMI-DISCRETE. MODEST MIDLEVEL LAPSE RATES AND COOL TEMPERATURES
   ALOFT /-14 DEG C AT 500 MB PER GSO 12Z RAOB/ WILL SUPPORT SEVERE
   HAIL. FAST STORM MOTION AND DCAPE NEAR 1000 J/KG ALSO WILL SUPPORT
   STRONG/LOCALLY DAMAGING WIND GUSTS. WHILE THE TORNADO THREAT IS
   EXPECTED TO REMAIN LOW...HI-RES GUIDANCE SUGGESTS SOME BACKING OF
   LOW-LEVEL WINDS IS POSSIBLE AS A WEAK SURFACE TROUGH DEVELOPS AHEAD
   OF THE COLD FRONT ACROSS CENTRAL NC INTO N-CENTRAL SC. A BRIEF
   TORNADO CANNOT BE RULED OUT IF THIS OCCURS.