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Potential severe storms for Sat, Jan 11


Brick Tamland

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I don't see any severe (at this point) for my area, but it could be something to watch for those to my north and east

 

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CST THU JAN 09 2014

VALID 111200Z - 121200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SOUTHEAST
STATES/CAROLINAS...

...SOUTHEAST STATES/CAROLINAS...
AS A PROGRESSIVE LONGWAVE PATTERN PERSISTS OVER THE CONUS ON
SATURDAY...A POTENT UPPER TROUGH IS EXPECTED TO MAKE A STEADY
EASTWARD ADVANCEMENT FROM THE MS RIVER VALLEY VICINITY EARLY
SATURDAY TO THE EASTERN SEABOARD BY EARLY SUNDAY. AMPLE FORCING FOR
ASCENT ASIDE...A CONSIDERABLE STRENGTHENING OF THE DEEP-LAYER WIND
FIELD IS EXPECTED TO OCCUR DURING THE PERIOD...HIGHLIGHTED BY 100+
KT MID-LEVEL SOUTHWESTERLY WINDS WITH 50-70 KT WINDS AROUND 850
MB...COINCIDENT WITH AN INCREASINGLY MOIST PRE-COLD FRONTAL WARM
SECTOR.

FORECAST UNCERTAINTIES INCLUDE THE TIMING OF THE AFOREMENTIONED COLD
FRONT AND THE EXTENSIVENESS OF EARLY DAY PRECIPITATION...ASIDE FROM
THE EXACT DEGREE OF WARM SECTOR MOISTENING AND DIURNAL
DESTABILIZATION. REGARDLESS...IF/WHERE AT LEAST SUFFICIENT
DESTABILIZATION MATERIALIZES OF AT LEAST A FEW HUNDRED J/KG OF
MLCAPE...THE POTENTIAL WILL EXIST FOR HIGHLY ORGANIZED/STRONG STORM
MODES CAPABLE OF WIND DAMAGE AND A TORNADO RISK GIVEN THE HIGH
DEGREE OF VERTICAL SHEAR/SRH.

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Phew I'm glad someone started this thread, I was having a hard time following this threat with all the talk about the upcoming snowstorm in our medium range disco thread. Personally I'm worried the rain drops will be so large it will damage my blades of grass. GSP is going with a high likelyhood of cloud cover tomorrow and Saturday, I hope people are prepared for this as it may catch people off guard.

 

 

:axe:

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Good thread. Winter is boring me numb so time to dream of spring. JIT (just in time) moisture will probably fail, but I could see warming enough with this vigorous system. However JIT moisture and cloud cover present challenges. Wind fields should support locally damaging straight winds. I don't know about TOR but low-top convection can surprise. How about some graupel on the back side? Makes for a good desk/sofa chase while watching NFL.

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Adding the text:

 

  ...SOUTHERN INTO MIDDLE ATLANTIC COASTAL AREAS...

   ALTHOUGH THE APPROACHING MID/UPPER TROUGH IS FORECAST TO EVENTUALLY

   TAKE ON A NEGATIVE TILT ORIENTATION...APPRECIABLE STEEPENING OF

   MID-LEVEL LAPSE RATES DOES NOT APPEAR LIKELY BEFORE LOW-LEVEL COLD

   ADVECTION DIMINISHES CONVECTIVE POTENTIAL SATURDAY NIGHT.

   HOWEVER...AN INFLUX OF SEASONABLY HIGH MOISTURE CONTENT

   /PRECIPITABLE WATER AOA 1.5 INCHES/ PROBABLY WILL CONTRIBUTE TO AT

   LEAST WEAK CAPE EAST OF THE CENTRAL/SOUTHERN APPALACHIANS.  THIS IS

   EXPECTED TO BE BOUNDARY LAYER BASED ACROSS NORTHERN FLORIDA AND

   SOUTHERN GEORGIA...INTO PORTIONS OF THE CAROLINA PIEDMONT AND MID

   ATLANTIC COASTAL PLAIN...WHILE A RESIDUAL COOL/STABLE SURFACE BASED

   LAYER LINGERS CLOSER TO THE BLUE RIDGE AND ACROSS PARTS OF THE

   NORTHERN DELMARVA PENINSULA.

   GIVEN THE INSTABILITY...FORCING NEAR THE WEAK SURFACE WAVE...AND

   AHEAD OF THE APPROACHING UPSTREAM IMPULSE...IS EXPECTED TO

   CONTRIBUTE TO CONSIDERABLE CONVECTIVE DEVELOPMENT SATURDAY AFTERNOON

   INTO SATURDAY EVENING...WITH ONE OR MORE EVOLVING LINES OF

   THUNDERSTORMS.  IN THE PRESENCE OF STRONG VERTICAL SHEAR AND DEEP

   LAYER MEAN FLOW...INCLUDING A RATHER STRONG SOUTHERLY 850 MB JET

   WHICH MODELS GENERALLY SUGGEST MAY BE ON THE ORDER OF 50 TO 70

   KTS...STRONGEST CONVECTION WILL PROBABLY INCLUDE A RISK FOR DAMAGING

   WIND GUSTS.  THE ENVIRONMENT MAY EVEN BECOME CONDUCIVE TO

   SUPERCELLS...AT LEAST EMBEDDED WITHIN THE LINES...IF NOT

   DISCRETE...WITH A RISK FOR TORNADOES.

 

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Adding the text:

 

  ...SOUTHERN INTO MIDDLE ATLANTIC COASTAL AREAS...

   ALTHOUGH THE APPROACHING MID/UPPER TROUGH IS FORECAST TO EVENTUALLY

   TAKE ON A NEGATIVE TILT ORIENTATION...APPRECIABLE STEEPENING OF

   MID-LEVEL LAPSE RATES DOES NOT APPEAR LIKELY BEFORE LOW-LEVEL COLD

   ADVECTION DIMINISHES CONVECTIVE POTENTIAL SATURDAY NIGHT.

   HOWEVER...AN INFLUX OF SEASONABLY HIGH MOISTURE CONTENT

   /PRECIPITABLE WATER AOA 1.5 INCHES/ PROBABLY WILL CONTRIBUTE TO AT

   LEAST WEAK CAPE EAST OF THE CENTRAL/SOUTHERN APPALACHIANS.  THIS IS

   EXPECTED TO BE BOUNDARY LAYER BASED ACROSS NORTHERN FLORIDA AND

   SOUTHERN GEORGIA...INTO PORTIONS OF THE CAROLINA PIEDMONT AND MID

   ATLANTIC COASTAL PLAIN...WHILE A RESIDUAL COOL/STABLE SURFACE BASED

   LAYER LINGERS CLOSER TO THE BLUE RIDGE AND ACROSS PARTS OF THE

   NORTHERN DELMARVA PENINSULA.

   GIVEN THE INSTABILITY...FORCING NEAR THE WEAK SURFACE WAVE...AND

   AHEAD OF THE APPROACHING UPSTREAM IMPULSE...IS EXPECTED TO

   CONTRIBUTE TO CONSIDERABLE CONVECTIVE DEVELOPMENT SATURDAY AFTERNOON

   INTO SATURDAY EVENING...WITH ONE OR MORE EVOLVING LINES OF

   THUNDERSTORMS.  IN THE PRESENCE OF STRONG VERTICAL SHEAR AND DEEP

   LAYER MEAN FLOW...INCLUDING A RATHER STRONG SOUTHERLY 850 MB JET

   WHICH MODELS GENERALLY SUGGEST MAY BE ON THE ORDER OF 50 TO 70

   KTS...STRONGEST CONVECTION WILL PROBABLY INCLUDE A RISK FOR DAMAGING

   WIND GUSTS.  THE ENVIRONMENT MAY EVEN BECOME CONDUCIVE TO

   SUPERCELLS...AT LEAST EMBEDDED WITHIN THE LINES...IF NOT

   DISCRETE...WITH A RISK FOR TORNADOES.

 

 

That last paragraph does not sound good. Maybe we'll have some storms and not anything severe. Of course, that could be a good thing. You know the old tale about thunderstorms in winter.

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That last paragraph does not sound good. Maybe we'll have some storms and not anything severe. Of course, that could be a good thing. You know the old tale about thunderstorms in winter.

 

Yep.  If it thunders in winter, ten day later it will have thundered ten days ago.  Works every time.

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Severe wx indies are going up with each run of the GFS over eastern NC and eastern SC. This is definitely getting interesting. Haven't looked at the soundings but definitely seeing some hook like hodographs in some places.

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Severe wx indies are going up with each run of the GFS over eastern NC and eastern SC. This is definitely getting interesting. Haven't looked at the soundings but definitely seeing some hook like hodographs in some places.

 

I hope people pay attention to this. I think a lot of folks are thinking it's winter so we don't have to worry about anything. It's not even getting much attention here.

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Why did they take the 30% area out if indices are going up with each run?

Maybe they believe short term models over the GFS. There isn't much support for the GFS, I was just posting about a trend I saw.

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Why did they take the 30% area out if indices are going up with each run?

I'm not sure the 30% was warranted for the early Day 2 update, but based on their discussion, they seem to feel that the best pre-frontal convection stays offshore, hence backing down to 15%. This was based off of the 12z SPC WRF. The 15z SREF is coming in more robust with the severe potential.

 

While this setup could perform, there are some red flags. While wind fields are good on the speed side, directional shear is modest at best. Hodographs show some turning, but they're not classic by any means. Instability is not very impressive and clouds/debris during the morning could even further limit destabilization.

 

With all of this said, I think there will be some isolated severe wind gusts with a squall line associated with a cold front. While there could be a few discrete cells out in front, this is not looking like an outbreak. I'd imagine is there is a narrow band from the eastern Carolinas into southeastern Virginia that could have the greatest potential, but at the end of the day, I think severe reports will wind up more isolated as opposed to widespread.

 

Here's the 12z GFS sounding for RIC at 18z Saturday. You'd like to winds turning more around to the west with height:

post-533-0-21368700-1389386870_thumb.gif

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I'm not sure the 30% was warranted for the early Day 2 update, but based on their discussion, they seem to feel that the best pre-frontal convection stays offshore, hence backing down to 15%. This was based off of the 12z SPC WRF. The 15z SREF is coming in more robust with the severe potential.

 

While this setup could perform, there are some red flags. While wind fields are good on the speed side, directional shear is modest at best. Hodographs show some turning, but they're not classic by any means. Instability is not very impressive and clouds/debris during the morning could even further limit destabilization.

 

With all of this said, I think there will be some isolated severe wind gusts with a squall line associated with a cold front. While there could be a few discrete cells out in front, this is not looking like an outbreak. I'd imagine is there is a narrow band from the eastern Carolinas into southeastern Virginia that could have the greatest potential, but at the end of the day, I think severe reports will wind up more isolated as opposed to widespread.

 

Here's the 12z GFS sounding for RIC at 18z Saturday. You'd like to winds turning more around to the west with height:

attachicon.gifRIC.gif

I agree with the bolded........Thanks for stopping by Quincy :hug: 

 

Areas of NC look like the severe threat definitely ramped up possibly weak tor wise per 15z SREF just looking at low res stuff, no graphs or anything.

 

KCAE is in it a little bit more for SC also.

I'm not expecting any more than a rumble of thunder, a little breeze and a brief downpour as the front comes threw. The line will get a little stronger (as usual) just to the east of us  :lol: 

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Here's the 12z GFS sounding for RIC at 18z Saturday. You'd like to winds turning more around to the west with height:

attachicon.gifRIC.gif

 

Um, there is a ton of directional shear in that sounding. SSE at the surface veering to WSW in the upper levels is perfectly sufficient. Analysis of that sounding on twisterdata shows a long, sickle shaped hodograph in the lowest 3 km.

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Um, there is a ton of directional shear in that sounding. SSE at the surface veering to WSW in the upper levels is perfectly sufficient. Analysis of that sounding on twisterdata shows a long, sickle shaped hodograph in the lowest 3 km.

 

RAH's afternoon disco...

 

"SOUNDING HODOGRAPHS DEPICT

LONG CURVED PROFILES INDICATIVE OF CONVECTIVE LINES WITH POSSIBLE

SUPERCELLS. CONSIDERING THE STRENGTH OF THE WINDS IN THE LOWEST 10K

FEET...EXPECT STRONG WIND GUSTS WITH ANY BANDS OF CONVECTION THAT

DEVELOP WITH ISOLATED DAMAGING WIND GUSTS POSSIBLE. COULD SEE A FEW

ROTATING STORMS...ONE OR TWO EMBEDDED IN THE CONVECTIVE LINE ALONG

OF THE FRONT...AND A FEW STORMS WELL AHEAD OF THE LINE. THIS SUGGEST

A SLIGHT RISK FOR BRIEF TORNADOES SATURDAY AFTERNOON...MAINLY ALONG

AND EAST OF HIGHWAY 1."

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RAH's afternoon disco...

 

"SOUNDING HODOGRAPHS DEPICT

LONG CURVED PROFILES INDICATIVE OF CONVECTIVE LINES WITH POSSIBLE

SUPERCELLS. CONSIDERING THE STRENGTH OF THE WINDS IN THE LOWEST 10K

FEET...EXPECT STRONG WIND GUSTS WITH ANY BANDS OF CONVECTION THAT

DEVELOP WITH ISOLATED DAMAGING WIND GUSTS POSSIBLE. COULD SEE A FEW

ROTATING STORMS...ONE OR TWO EMBEDDED IN THE CONVECTIVE LINE ALONG

OF THE FRONT...AND A FEW STORMS WELL AHEAD OF THE LINE. THIS SUGGEST

A SLIGHT RISK FOR BRIEF TORNADOES SATURDAY AFTERNOON...MAINLY ALONG

AND EAST OF HIGHWAY 1."

 

 

And guess where I am? Right off US 1. Going to have to keep an eye on this. Seems the threat gets bigger and bigger as we get closer to tomorrow.

 

What a crazy winter. We have record cold, a ton of rain, and now severe weather to worry about, but still no snow.

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Um, there is a ton of directional shear in that sounding. SSE at the surface veering to WSW in the upper levels is perfectly sufficient. Analysis of that sounding on twisterdata shows a long, sickle shaped hodograph in the lowest 3 km.

 

RAH's afternoon disco...

 

"SOUNDING HODOGRAPHS DEPICT

LONG CURVED PROFILES INDICATIVE OF CONVECTIVE LINES WITH POSSIBLE

SUPERCELLS. CONSIDERING THE STRENGTH OF THE WINDS IN THE LOWEST 10K

FEET...EXPECT STRONG WIND GUSTS WITH ANY BANDS OF CONVECTION THAT

DEVELOP WITH ISOLATED DAMAGING WIND GUSTS POSSIBLE. COULD SEE A FEW

ROTATING STORMS...ONE OR TWO EMBEDDED IN THE CONVECTIVE LINE ALONG

OF THE FRONT...AND A FEW STORMS WELL AHEAD OF THE LINE. THIS SUGGEST

A SLIGHT RISK FOR BRIEF TORNADOES SATURDAY AFTERNOON...MAINLY ALONG

AND EAST OF HIGHWAY 1."

Yeah I saw some interesting hodos but haven't checked much recently as in on my cell. Definitely anything that spins up will be brief and the window is small but it's there.

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SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
948 PM EST FRI JAN 10 2014

NCC101-163-191-110300-
/O.CON.KRAH.SV.W.0001.000000T0000Z-140111T0300Z/
JOHNSTON NC-SAMPSON NC-WAYNE NC-
948 PM EST FRI JAN 10 2014

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1000 PM EST
FOR SOUTHERN JOHNSTON...NORTHEASTERN SAMPSON AND SOUTHWESTERN WAYNE
COUNTIES...

AT 946 PM EST...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE
OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS
LOCATED NEAR SPIVEYS CORNER...OR 15 MILES NORTH OF CLINTON...MOVING
NORTHEAST AT 30 MPH.

LOCATIONS IMPACTED INCLUDE... NEWTON GROVE... KEENER...VANN
CROSSROADS...SPIVEYS CORNER...PLAIN VIEW... GRANTHAM.

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