Potential Severe Weather Event 06/13/13

[DaculaWeather]

MESOSCALE DISCUSSION 1061
NWS STORM PREDICTION CENTER NORMAN OK
1219 PM CDT THU JUN 13 2013

AREAS AFFECTED...MIDDLE-ERN TN / NRN AL / NRN GA / WRN NC / UPSTATE
SC

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 131719Z - 131745Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...STORMS ARE EXPECTED TO DEVELOP OVER THE NEXT SEVERAL HOURS
ACROSS TN AND SPREAD E AND S INTO ADJACENT STATES. WIND DAMAGE WILL
BE THE PRIMARY HAZARD WITH THE EXPECTED ACTIVITY...AND ISOLD LARGE
HAIL MAY ACCOMPANY THE STRONGER UPDRAFTS.

DISCUSSION...17Z SURFACE MESOANALYSIS SHOWS A COLD FRONT DRAPED
ACROSS ERN KY WSWWD THROUGH THE KY/MO/TN BORDER VICINITY. VISIBLE
SATELLITE SHOWS A CU FIELD BECOMING AGITATED WITHIN SEVERAL
TRANSVERSE BANDS/GRAVITY WAVES PROPAGATING SEWD ACROSS THE TN VALLEY
--INDICATIVE OF A DESTABILIZING BOUNDARY LAYER. THE 12Z BNA RAOB
SHOWS A VERY UNSTABLE AIRMASS IN PLACE AND MODIFYING FOR EXPECTED
TEMPS IN MID 80S TO LOWER 90S GREATLY DIMINISHES CINH AND
EFFECTIVELY ERODES THE REMAINING CAP. ALTHOUGH LOW LEVEL CONFLUENCE
IS FOCUSES FARTHER NE INTO FAR NERN TN/SWRN VA...HEATING AND THE
TRAILING INFLUENCE OF THE CNTRL APPALACHIANS UPPER TROUGH WILL
LIKELY INITIATE STORMS OVER THE NEXT FEW HOURS...ZIPPERING SWWD WITH
TIME.

STRONG WLY FLOW IN THE 2-4 KM LAYER /40 KT/ AT KHTX AND KOHX AND
STEEPENING LOW LEVEL LAPSE RATES WILL SUPPORT DOWNWARD MOMENTUM
TRANSPORT IN THE FORM OF DMGG WIND GUSTS ONCE ROBUST UPDRAFTS
DEVELOP/INTENSIFY. STRONGER LOW-MID LEVEL WLY FLOW IS NOTED AT KMRX
/50 KT AT 2 KM/...SIGNALING A HIGHER CONCENTRATION FOR DMGG STRONG
TO SEVERE WIND GUSTS. AT LEAST SOME POSSIBILITY FOR A TORNADO MAY
EXIST DUE TO THE STRENGTH OF FLOW. AS SUCH...STORMS WILL LIKELY
CONSOLIDATE INTO A LOOSE CONGLOMERATION OF SMALL LINE SEGMENTS/BOWS
AS THE MOVE EWD.

[Cold Rain]

Its pretty insane outside here right now, a oppressive airmass for sure currently 95 with a 73 DP MLcape is over 5000

Those are some amazing numbers for these parts. Any chance higher CAPE values work back west?

[downeastnc]

Any ideas as to why there is no tornado watch?

 

Cause the wind field doesnt support tornados really, there might be some QLCS type tornadoes similar to what ST Louis saw a few weeks back but it is unlikely, gustnados on the other hand could be a threat....

[Brick Tamland]

Wonder when they will pull the trigger on a severe thunderstorm watch for NC.

[Cold Rain]

Wonder when they will pull the trigger on a severe thunderstorm watch for NC.

Later.

[downeastnc]

Those are some amazing numbers for these parts. Any chance higher CAPE values work back west?

I doubt they get that high further west but they dont have too its plenty unstable there, the real question for my area is timing, this far east we might not see the line till 7-8pm by then the numbers will be back down as we lose the heat of the day a line of storms had formed and moved through here in the next few hrs it would have been like last July 1st with widespread 60-100 mph winds.

 

Still I suspect this will be one of those massive squall lines that will have 100's of wind reports with it and lots of folks in NC gonna see winds 50-75 mph and a few places further east ( RAH to the east)  might see 75-100 mph in a few spots if it gets here soon enough.

[Brick Tamland]

I doubt they get that high further west but they dont have too its plenty unstable there, the real question for my area is timing, this far east we might not see the line till 7-8pm by then the numbers will be back down as we lose the heat of the day a line of storms had formed and moved through here in the next few hrs it would have been like last July 1st with widespread 60-100 mph winds.

 

Still I suspect this will be one of those massive squall lines that will have 100's of wind reports with it and lots of folks in NC gonna see winds 50-75 mph and a few places further east ( RAH to the east)  might see 75-100 mph in a few spots if it gets here soon enough.

 

It might still be around 90 here at 7:00.

[Solak]

Just pulled this off Facebook from NWS-RAH

 

 

US National Weather Service Raleigh NC

 

GOES-14 will be collecting special 1-minute visible satellite imagery today to support severe weather operations. The Super Rapid Scan refresh rate is a preview of what will be available regularly with future GOES-R spacecraft.

The data can be accessed at the URL below. The loop is courtesy of the Cooperative Institute for Research in the Atmosphere (CIRA). Crank up the animation speed and enjoy.

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=dev%2Flindsey%2Floops%2Fgoes14_vis2&image_width=1020&image_height=720&number_of_images_to_display=50

[jburns]

You should stop by and see Burns!

 See my post in the banter thread.

[Cold Rain]

I doubt they get that high further west but they dont have too its plenty unstable there, the real question for my area is timing, this far east we might not see the line till 7-8pm by then the numbers will be back down as we lose the heat of the day a line of storms had formed and moved through here in the next few hrs it would have been like last July 1st with widespread 60-100 mph winds.

 

Still I suspect this will be one of those massive squall lines that will have 100's of wind reports with it and lots of folks in NC gonna see winds 50-75 mph and a few places further east ( RAH to the east)  might see 75-100 mph in a few spots if it gets here soon enough.

Thanks! I think the parameters are there across the board for many to see severe, as you said. If the line hangs together over the mountains, I would think it would be able to intensify and organize better, which would increase the liklihood of widespread damaging winds. With the wet ground, as has been mentioned, it won't take nearly as much of an effort to down trees. Should be lots of lightening as well. Looking forward to a noisy evening.

[Brick Tamland]

MESOSCALE DISCUSSION 1062
   NWS STORM PREDICTION CENTER NORMAN OK
   1253 PM CDT THU JUN 13 2013

   AREAS AFFECTED...SERN VA AND NERN NC

   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

   VALID 131753Z - 131930Z

   PROBABILITY OF WATCH ISSUANCE...95 PERCENT

   SUMMARY...THUNDERSTORM CLUSTERS AND LINE SEGMENTS WILL ENTER
   PORTIONS OF SERN VA AND NERN NC THIS AFTERNOON. AS THIS OCCURS...THE
   THREAT FOR WIDESPREAD DAMAGING WINDS AND LARGE HAIL WILL INCREASE.
   WW WILL LIKELY BE NEEDED.

   DISCUSSION...EARLY AFTERNOON SURFACE OBSERVATIONS AND OBJECTIVE
   ANALYSIS GUIDANCE INDICATE THE ENVIRONMENT ACROSS SERN VA AND ERN NC
   IS BECOMING STRONGLY UNSTABLE...WITH TEMPERATURES NEAR 90F AND
   DEWPOINTS IN THE LOW 70S AIDING IN MLCAPE VALUES FROM 2500-4000
   J/KG. AREA VWP/S SHOW MAINLY DEEP-LAYER WLY FLOW INCREASING TO 50 KT
   AT 3 KM AGL. GIVEN THIS COMBINATION OF CAPE AND SHEAR...NUMEROUS
   MULTICELL CLUSTERS/LINE SEGMENTS AND A FEW SUPERCELLS WILL BE
   POSSIBLE AS A COLD FRONT APPROACHES FROM THE W. THESE STORMS WILL
   POSE A THREAT FOR WIDESPREAD DAMAGING WINDS AND LARGE HAIL. AREA
   WILL NEED A WW ISSUANCE DURING THE NEXT HOUR.

 

[calculus1]

Wonder when they will pull the trigger on a severe thunderstorm watch for NC.

 

Does it even matter?  We know T-storms are possible whether the NWS decides to issue a watch or not.  The watch is for the public at large; it has no really meaningful addition to our discussion here other than to say that true mets agree with what many on here have already posted.  It's similar to WWAs and WSWs in the cold months:  whether we get those warnings is irrelevant; whether it snows is what we all care about, with or without a WWA or WSW.

 

I've been in Ocean Isle Beach, NC, all week.  I'm interested to see whether we'll get much strong stuff tonight here on the coast.  Several of our party are going shark fishing (not me) from 6-10 tonight.  That should be fun to experience in the midst of possible severe thunderstorms on the open water!  

[1234snow]

First line of storms was intense. Winds were probably around 50 mph with heavy rain. Some people lost power. Now warned for the second line about to hit. Can't wait to see what these storms do after they cross the mountains and head y'all's way.

[Brick Tamland]

Oh wow!

 

2:10 PM: A Particularly Dangerous Situation Severe Thunderstorm Watch has been issued for central and eastern NC through 10 PM EDT. Widespread damaging winds up to 80 MPH are expected across the watch area. Dangerous lightning, large hail, and isolated tornadoes are also possible.

[jburns]

Does it even matter?  We know T-storms are possible whether the NWS decides to issue a watch or not.  The watch is for the public at large; it has no really meaningful addition to our discussion here other than to say that true mets agree with what many on here have already posted.  It's similar to WWAs and WSWs in the cold months:  whether we get those warnings is irrelevant; whether it snows is what we all care about, with or without a WWA or WSW.

 

I've been in Ocean Isle Beach, NC, all week.  I'm interested to see whether we'll get much strong stuff tonight here on the coast.  Several of our party are going shark fishing (not me) from 6-10 tonight.  That should be fun to experience in the midst of possible severe thunderstorms on the open water!  

 

Boat could capsize and the hunters become the hunted.  That could make some exciting stories for future generations sitting in front of the fire and listening to Grandpa Stumpy.

[jburns]

It looks like the second line is catching up with the first over the mountains.

[ILMRoss]

Most of NC just got put in a PDS severe watch.

[Brick Tamland]

210 PM EDT Thu Jun 13 2013


The National Weather Service has issued Severe Thunderstorm Watch
308 in effect until 10 PM EDT this evening for the following
areas

In North Carolina this watch includes 31 counties

In central North Carolina

Alamance              Anson                 Chatham             
Cumberland            Davidson              Durham              
Edgecombe             Forsyth               Franklin            
Granville             Guilford              Halifax             
Harnett               Hoke                  Johnston            
Lee                   Montgomery            Moore               
Nash                  Orange                person              
Randolph              Richmond              Sampson             
Scotland              Stanly                Vance               
wake                  Warren                Wayne               
Wilson               

This includes the cities of...Albemarle...Asheboro...Burlington...
Chapel HIll...Clinton...Durham...Fayetteville...Goldsboro...
Greensboro...Henderson...High Point...Laurinburg...Lexington...
Lillington...Louisburg...Nashville...Oxford...Pittsboro...
Raeford...Raleigh...Roanoke Rapids...Rockingham...Rocky Mount...
Roxboro...Sanford...Smithfield...Southern Pines...Troy...
Wadesboro...Warrenton...Wilson and Winston-Salem.

This is a particularly dangerous situation. Those in the threatened
area are urged to review severe weather safety rules and to listen
to radio... television... and NOAA Weather Radio for further
information and possible warnings.

[Brick Tamland]

From RAH:

 

2:25 PM: The Triad can expect severe thunderstorms between 3:30 and 5 PM this afternoon. The Triangle will see the threat from 4:30 to 6 PM. Exercise caution during evening commutes!

[WxFreak11]

Wow..don't recall the last PDS thunderstorm watch for this area. Keep an eye to the sky folks and be safe.

[downeastnc]

Thanks! I think the parameters are there across the board for many to see severe, as you said. If the line hangs together over the mountains, I would think it would be able to intensify and organize better, which would increase the liklihood of widespread damaging winds. With the wet ground, as has been mentioned, it won't take nearly as much of an effort to down trees. Should be lots of lightening as well. Looking forward to a noisy evening.

 

Its going to be insanely bad regardless I think, the setup is as good as it gets to get big winds to the surface, Dcape which measures the downdraft potential is 1200-1400 for most of NC and that is typically as high as it ever gets around here in the worst ( or best depending on your POV ) setups.

[Brick Tamland]

Wow..don't recall the last PDS thunderstorm watch for this area. Keep an eye to the sky folks and be safe.

 

Same here. The last PDS event I can recall is the tornado watch when we had the 4/16/11 tornado in Raleigh.

[WxFreak11]

Same here. The last PDS event I can recall is the tornado watch when we had the 4/16/11 tornado in Raleigh

It's definitely not a watch that is used lightly and people really need to pay close attention to prospects of severe straight line winds, isolated tornadoes and even hail damage.

[Cold Rain]

Same here. The last PDS event I can recall is the tornado watch when we had the 4/16/11 tornado in Raleigh.

I was just about to post that. That's the last PDS watch I remember being under. I never remember being under a PDS Severe Storm watch.

[nrgjeff]

Sandy type messaging issue. They go PDS severe, and even mention tornadoes. Also they emphasize that widespread straight winds are an acute concern. All great info for us. All confusing for the public. Should be a tornado watch. Just MHO. Remember Chicago had to add counties to the tornado watch yesterday on top of their severe watch in the 'burbs.

[Brick Tamland]

[Cold Rain]

Its going to be insanely bad regardless I think, the setup is as good as it gets to get big winds to the surface, Dcape which measures the downdraft potential is 1200-1400 for most of NC and that is typically as high as it ever gets around here in the worst ( or best depending on your POV ) setups.

Yeah, the elements certainly look to be coming together well. The watch text says the area of greatest concern is near the VA/NC boarder. The SPC Meso page seems to somewhat corroborate. There's an annoying tongue of lower instability right through Raleigh off to the SW. Not sure what that's about, but it's been persistently there all day.

[NCsandhills]

Sandy type messaging issue. They go PDS severe, and even mention tornadoes. Also they emphasize that widespread straight winds are an acute concern. All great info for us. All confusing for the public. Should be a tornado watch. Just MHO. Remember Chicago had to add counties to the tornado watch yesterday on top of their severe watch in the 'burbs.

Exactly what I was saying earlier, I do agree...should just be a tornado watch. They've already stated numerous times that tornadoes can't be ruledout, meaning def possible.  There is 1 tor warning in VA right now, too.  PDS svr storm and mentioning tornadoes, but not even a watch...just a few days ago we had a tornado watch, and conditions seemed less favorable then.

[jburns]

Some nasty stuff around Lynchburg, VA.

[Brick Tamland]

Exactly what I was saying earlier, I do agree...should just be a tornado watch. They've already stated numerous times that tornadoes can't be ruledout, meaning def possible.  There is 1 tor warning in VA right now, too.  PDS svr storm and mentioning tornadoes, but not even a watch...just a few days ago we had a tornado watch, and conditions seemed less favorable then.

 

It certainly is confusing. It looks like the storms are a given, so maybe it would be better to have a tornado watch and issue STS warnings when needed.