2017 General Severe Weather thread

[downeastnc]

SPC has all of NC/SC and a good chunk of GA as a 5% tornado threat.....

[janetjanet998]

I can't believe FL was only in a 2% TOR risk in the 0630 outlook....15% wind low too

they just sent out a meso for an upgrade for FL....

also probs may needed to be raised over SC/NC too 

WS STORM PREDICTION CENTER NORMAN OK  
655 AM EDT WED MAY 24 2017  
  
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
  
* TORNADO WATCH FOR PORTIONS OF   
  NORTH FLORIDA  
  SOUTHERN GEORGIA  
  COASTAL WATERS  
  
* EFFECTIVE THIS WEDNESDAY MORNING AND AFTERNOON FROM 655 AM  
  UNTIL 300 PM EDT.  
  
* PRIMARY THREATS INCLUDE...  
  A FEW TORNADOES POSSIBLE  
  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE  
  ISOLATED LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE  
  
SUMMARY...SEVERE THUNDERSTORMS CAPABLE OF A FEW TORNADOES ALONG WITH  
DAMAGING WINDS ARE EXPECTED TO GRADUALLY INCREASE THROUGH THE  
MORNING. THIS INCLUDES AN EARLY-DAY RISK ACROSS THE NORTH-CENTRAL  
PENINSULA NEAR A REMNANT BOUNDARY, WHILE OTHER STORMS WILL MOVE IN  
FROM THE GULF OF MEXICO AND FLORIDA PANHANDLE AND INTENSIFY WITHIN A  
VERY MOIST AND INCREASINGLY UNSTABLE ENVIRONMENT.  

 

[downeastnc]

Good write up by RAH about todays storm chances...

...Severe storms possible today through this evening, and flood
watch remains in effect into tonight...

The risk of heavy downpours producing localized flooding and high
water on creeks and rivers persists today, with the potential for an
additional 1-2" falling in areas with saturated soil and high water
in creeks. However, severe weather is also a significant concern
today, with several factors appearing to line up ideally to support
vigorous convection, including the possibility of discrete severe
cells this afternoon and a more organized line favoring bowing
segments crossing the area late afternoon into the evening.

A large and strong mid level low will drop S/SE through the mid and
lower Miss Valley into the Mid South today/tonight and weaken, while
another low is spawned over the central Ohio Valley. Three
noteworthy features can be seen on the latest surface analysis: a
roughly west-east but wavy frontal zone across the northern
Piedmont, a warm front extending through central GA and southern SC,
and a cold front to our west through the W Ohio Valley and lower
Miss Valley. The latest high-res models take the Piedmont front
northward gradually this morning. This is expected to be followed by
a northward surge (or perhaps a jump, with the onset of mixing) of
the warm front well into NC by early/mid afternoon, and finally, the
west-to-east passage of the cold/occluded front (featuring a triple
point low tracking near or just NW of the Triad) very late evening
through the overnight hours. We`re already seeing scattered
convection along and north of the warm front over GA/SC, and as this
front shifts/jumps northward with increasing destabilization and an
improving wind field over NC, expect development of discrete
northward-moving cells, starting in the southern CWA, by early to
mid afternoon. Such development is suggested by the NAM Nest, HRRR,
and SPC`s SSEO. The low stratus (NW CWA) and stratocu (SE CWA) will
initially limit insolation and destabilization through the morning
hours, thus limiting shower coverage early today over central NC, so
will start the day with low pops. But the wind field will improve
through a deep layer as afternoon approaches, with a 60-80 kt 500 mb
jet spreading from the FL panhandle NE through the Carolinas, and a
30-40 kt cyclonic 850 mb SSW jet over the Southeast nosing into NC.
The GFS brings MUCAPE up to 750-1500 J/kg (NW-SE) this afternoon,
likely due in part to a batch of higher mid-level lapse rates now
over the north-central/northeast Gulf moving NE through GA/SC/NC
later today, as well as the low level heating and resident moist low
levels. On top of the increasingly favorable kinematics and
thermodynamics is the increase in mid level DPVA and upper
divergence, the latter associated with an accelerating southerly jet
streak extending from SW GA through the eastern Ohio Valley later
today. All of this supports the development and maintenance of
strong to severe convection this afternoon into this evening, with
large hail possible, along with damaging wind gusts. And, with the
retreating N Piedmont frontal zone potentially providing a rich
source of low level vorticity and high shear, there will be a chance
for a tornado or two, with the greatest threat over the N and W
Piedmont.
 

[janetjanet998]

I am surprised by the lack of activity in this thread enhanced  risk now for parts of GA and SC

 

10% TOR probs for northern FL

 

AY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
0755 AM CDT WED MAY 24 2017  
  
VALID 241300Z - 251200Z  
  
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF  
FL/GA/SC...  
  
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TN  
VALLEY/SOUTHERN APPALACHIANS/SOUTHEAST...  
  
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE  
SOUTHEAST STATES TO OH VALLEY/MID-ATLANTIC STATES...  
   
..SUMMARY  
  
SEVERE STORMS ARE EXPECTED TODAY INTO TONIGHT ACROSS A LARGE PORTION  
OF THE SOUTHEAST STATES, INCLUDING THE POTENTIAL FOR DAMAGING  
THUNDERSTORM WINDS AND TORNADOES. OTHER MORE ISOLATED SEVERE STORMS  
WILL BE POSSIBLE AS FAR NORTH AS THE MIDDLE OHIO RIVER VALLEY.  
   
..FLORIDA AND SOUTHEAST STATES  
  
AN UPPER LOW OVER THE LOWER MO VALLEY EARLY THIS MORNING WILL  
CONTINUE TO DIG SOUTH-SOUTHEASTWARD TOWARD THE MID-SOUTH AND LOWER  
MS RIVER VALLEY VICINITY. A PRECEDING VORT MAX WILL SPREAD  
NORTH-NORTHEASTWARD ACROSS THE TN/MIDDLE OH VALLEY, WHILE AN  
ADDITIONAL TROUGH-BASED-EMBEDDED VORT MAX SPREADS EAST/NORTHEASTWARD  
ALONG THE GULF COAST TOWARD GA/CAROLINAS BY TONIGHT.  
  
AHEAD OF THE AFOREMENTIONED UPPER TROUGH, A CONSIDERABLE  
STRENGTHENING OF DEEP-LAYER/LOW-LEVEL WINDS WILL OCCUR THROUGH THE  
AFTERNOON AND EVENING, MOST NOTABLY ACROSS NORTHERN/CENTRAL PORTIONS  
OF THE FL PENINSULA AND SOUTH GA NORTHEASTWARD INTO PIEDMONT/COASTAL  
AREAS OF THE CAROLINAS, WITH AN EXPECTED INCREASE TO 40-55 KT FOR  
SOUTHWESTERLY WINDS AROUND 850 MB (OR 1-2 KM AGL) WHILE 700 MB/3-KM  
AGL WINDS INCREASE TO 50+ KT.  
  
MULTIPLE ROUNDS OF POTENTIALLY SEVERE CONVECTION WILL AFFECT PARTS  
OF THE REGION THROUGH THE AFTERNOON AND EVENING. THE LATEST  
OBSERVATIONAL DATA AND SHORT-TERM GUIDANCE SUGGEST THAT THE MOST  
CONCENTRATED AND SEMI-FOCUSED SEVERE RISK SHOULD EXIST ACROSS  
CENTRAL/NORTH-CENTRAL PARTS OF THE FL PENINSULA AND SOUTHEAST GA  
TODAY INTO THIS EVENING. A VERY MOIST AIR MASS WITH SURFACE  
DEWPOINTS IN THE 70S ALREADY EXISTS ACROSS THE FL PENINSULA.  
  
IN TERMS OF AN INITIAL EARLY-DAY RISK, AS HAS ALREADY BEEN OBSERVED  
IN THE PRE-DAWN HOURS, A FEW SUPERCELLS REMAIN A POSSIBILITY ACROSS  
THE NORTH-CENTRAL FL PENINSULA IN VICINITY OF A REMNANT BOUNDARY.  
ADDITIONAL SOMEWHAT MORE BANDED STORMS WILL MOVE IN FROM THE EASTERN  
GULF OF MEXICO THROUGH THE AFTERNOON/EARLY EVENING, WITH ADDITIONAL  
INLAND DEVELOPMENT ACROSS NORTH FL INTO GA. ANY CLUSTER-PRECEDING  
SEMI-DISCRETE STORMS MAY POSE A TORNADO RISK AS LOW-LEVEL SHEAR  
GRADUALLY INCREASES AND ADDITIONAL DESTABILIZATION OCCURS, WHILE  
DAMAGING WINDS WILL BE A MORE CERTAIN POSSIBILITY THROUGH THE  
AFTERNOON AND EVENING.  
  
FARTHER NORTH, STORMS ARE EXPECTED TO BEGIN INCREASING IN COVERAGE  
ACROSS CENTRAL AND NORTHERN GEORGIA AND INTO THE CAROLINAS BY  
MIDDAY/EARLY AFTERNOON, WITH STORM MODE LIKELY TO BE A COMBINATION  
OF CELLS AND BROKEN BANDS PER SOME DEGREE OF FORECAST VEER-BACK-VEER  
(WITH HEIGHT) WIND PROFILES. SEE MESOSCALE DISCUSSION 825 FOR  
ADDITIONAL SHORT-TERM DETAILS. MULTIPLE ROUNDS OF CONVECTION ARE  
EXPECTED, WITH ANY LACK OF INSTABILITY SOMEWHAT OFFSET BY AMPLY  
STRONG/WEAKLY VEERING FLOW WITH HEIGHT. ALONG WITH RISK FOR LOCALLY  
DAMAGING WINDS AND MARGINAL HAIL, ISOLATED TORNADOES WILL ALSO BE  
POSSIBLE. A WIND DAMAGE/TORNADO RISK MAY EXTEND AS FAR NORTH AS THE  
MAIN WARM FRONT EXPECTED TO LIE OVER NORTHERN NORTH  
CAROLINA/SOUTHERN VIRGINIA BY MID TO LATE AFTERNOON INTO EVENING.  
   

[janetjanet998]

GENT - IMMEDIATE BROADCAST REQUESTED  
TORNADO WATCH NUMBER 262  
NWS STORM PREDICTION CENTER NORMAN OK  
1000 AM EDT WED MAY 24 2017  
  
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
  
* TORNADO WATCH FOR PORTIONS OF   
  NORTHERN GEORGIA  
  WESTERN NORTH CAROLINA  
  UPSTATE SOUTH CAROLINA  
  SOUTHEASTERN TENNESSEE  
  
* EFFECTIVE THIS WEDNESDAY MORNING AND EVENING FROM 1000 AM UNTIL  
  600 PM EDT.  
  
* PRIMARY THREATS INCLUDE...  
  A FEW TORNADOES LIKELY  
  SCATTERED DAMAGING WIND GUSTS TO 70 MPH LIKELY  
  ISOLATED LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE  
  
SUMMARY...THUNDERSTORMS NOW DEVELOPING EAST NORTHEAST OF THE UPPER  
TENNESSEE VALLEY WILL INCREASE IN COVERAGE AND INTENSITY NEAR AND TO  
THE EAST OF THE SOUTHERN APPALACHIANS THROUGH THIS AFTERNOON.  THIS  
MAY INCLUDE A FEW SUPERCELLS CAPABLE OF PRODUCING TORNADOES, AND  
INCREASING POTENTIAL FOR DAMAGING WIND GUSTS AS ACTIVITY MOVES ALONG  
A WARM FRONT EXTENDING ACROSS THE REGION.  

[jburns]

6 hours ago, janetjanet998 said:

I am surprised by the lack of activity in this thread enhanced  risk now for parts of GA and SC

 

10% TOR probs for northern FL

   

1

This is the SE forum.  We specialize in long threads about non-existant snowfall.  Real weather kind of creeps us out.

[Santa Clause]

Downeast is great here, otherwise we need andy and Chinook to keep it going.

[Solak]

NWS Raleigh‏Verified account @NWSRaleigh 11m11 minutes ago

 

 

Expecting lots of hail reports today, Here are 2 graphics to help identify the correct size. One for you visual types, the other in a chart.

[nrgjeff]

Sunday May 28 that Carolina Alley marginal risk may turn into more like slight or enhanced. Looks like a lifting warm front and/or outflow with short-wave coming. High dews are driving CAPE values up. LLJ may be awful veered, but always watch a boundary in late May.

[yotaman]

10 minutes ago, nrgjeff said:

Sunday May 28 that Carolina Alley marginal risk may turn into more like slight or enhanced. Looks like a lifting warm front and/or outflow with short-wave coming. High dews are driving CAPE values up. LLJ may be awful veered, but always watch a boundary in late May.

Not to mention temps expected to soar into the low 90's for much of the region.

[Solak]

For Saturday, May 27

[shaggy]

3k ham runs a nice mcs through the central part of the state. Nice line if it comes to fruition.

[shaggy]

Per mhx the nam for monday has some pretty strong instability. Certainly has the potential to be a bad severe day.

Monday-Monday night...Models generally agree on more widespread
convective threat with stronger short wave trough and surface
cold front moving toward area during peak afternoon heating. GFS
and NAM indicating LIs to -10 and CAPEs to near 5000 with deep
layer shear increasing to 40-50 KT, thus increasing concern for
strong to severe storms and SPC day 3 Outook of Slight Risk of
severe for entire area. Keeping POPs in 40-50% range for now.
Guidance indicates low level thicknesses building to near 1430
meters, supportive of max temps 90-94 inland of coast. Lows
Monday night remaining muggy 70-74.

[downeastnc]

3 hours ago, shaggy said:

Per mhx the nam for monday has some pretty strong instability. Certainly has the potential to be a bad severe day.

Monday-Monday night...Models generally agree on more widespread
convective threat with stronger short wave trough and surface
cold front moving toward area during peak afternoon heating. GFS
and NAM indicating LIs to -10 and CAPEs to near 5000 with deep
layer shear increasing to 40-50 KT, thus increasing concern for
strong to severe storms and SPC day 3 Outook of Slight Risk of
severe for entire area. Keeping POPs in 40-50% range for now.
Guidance indicates low level thicknesses building to near 1430
meters, supportive of max temps 90-94 inland of coast. Lows
Monday night remaining muggy 70-74.

NAM 3K flipping all around 00Z was nasty for central and eastern NC especially the northern half....06Z has basically nothing.  If those parameters above play out then it would be a really rough day, probably some serious straight line wind threats, a front hitting during peak heating with that kind of instability....I will believe it when I see it. Almost reminds me of July 1 2012 though not as unstable ( since that is pretty much the  most unstable airmass ever lol ) 

https://www.weather.gov/mhx/Jul012012EventReview

Violent severe thunderstorms swept through Eastern North Carolina during the afternoon and evening of Sunday July 1, 2012, killing three people, one in a collapsed building, and two due to a falling tree. The deadly thunderstorms were fueled by the extreme heat affecting the Southeast, coupled with unusually high levels of moisture. The extraordinary heat and moisture caused high levels of atmospheric instability rarely seen. The Convective Available Potential Energy (CAPE) in Eastern North Carolina and South Carolina at 2 pm EDT Sunday was 5000 to 6000 J/kg, with a lifted index of -14. The Morehead City NWS office analyzed CAPE levels in excess of 7000 J/kg (Figure 1) in the region, which is a truly rare occurrence.

[Solak]

Fire, reload, fire again.

Brad Panovich‏Verified account @wxbrad 32m32 minutes ago

 

 

These will be scattered late day & evening storms so still plenty of nice weather this weekend, but the storms that form strong-severe.

[downeastnc]

The hi res models are not very impressive with today, kinda surprised to see a slight risk.....of course thats means we probably get nailed.

[Solak]

Mesoscale Discussion 874

< Previous MD

Mesoscale Discussion 0874 NWS Storm Prediction Center Norman OK 0511 PM CDT Sat May 27 2017 Areas affected...far southeastern WV...western and southwestern VA...eastern TN...and northwest NC Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 272211Z - 272315Z Probability of Watch Issuance...80 percent SUMMARY...Severe thunderstorms capable of large hail/damaging gusts will likely move into the area from the west early this evening. DISCUSSION...Radar mosaic shows scattered strong to severe thunderstorms generally to the west of the spine of the Appalachians but this activity is forecast to move east of the the existing severe thunderstorm watches early this evening. Surface temperatures into the upper 70s-lower 80s degrees F and dewpoints in the 62-66 degrees F range ---resulting in moderate buoyancy (1500 J/kg MLCAPE). Effective shear more than adequate for storm organization (35-40 kt) will facilitate both severe multicell and supercell structures with the stronger storms. Large hail and damaging gusts (50-65 mph) are possible with the more intense cores.

[kvegas-wx]

This bowed line of tstorms is exploding over the triad.  Folks southeast are in for a bumpy ride the next 2-3 hours.  Just came through kernersville and certainly got my attention.

[NCSNOW]

Davie county had some 50 mph gust. Not good after mid week tornado. Line fixing to roll through mby. Several more to go next couple of days.

[calculus1]

Crazy severe storm rolled through around 1 AM here. 1.25 inches of rainfall in about 30 min. Tons of lightning.

Sent from my 6045O using Tapatalk

[LithiaWx]

6 hours ago, calculus1 said:

Crazy severe storm rolled through around 1 AM here. 1.25 inches of rainfall in about 30 min. Tons of lightning.

Sent from my 6045O using Tapatalk
 

We had a severe warned storm hit about 4-5am last night.  Woke up the whole house.  Had a scared 4 year old and a crying infant.  

 

The lightning was intense!  I wish I had captured the radar image because it was a nasty large bowed out line.  

[downeastnc]

Nam has a cluster firing over central NC and heading east this afternoon, the HRRR is weaker with it, of course neither of them really called for that squall line out west late last night either, so it looks like it has more to do with timing these MCS or their remnants which is giving the hi res models trouble. 

Might be seeing the cap finally breaking down in south central NC, also you can kinda see a mid level rotation lifting NE out of NC on this loop as well , and the storms firing in NE NC as a result....

http://www.ssd.noaa.gov/goes/east/wfo/rah/mflash-vis.html

[downeastnc]

Appears the Nam was on to something as a cluster/line is trying to get going just east of Hickory to Triad.....just need to see if it can hold up and move east and last till the coast.

[LithiaWx]

Slight risk today in the SE.   

[Solak]

Day 3 of slight risk. Nothing to show around here so far. Wondering if the Gulf storms will interfere with moisture transport later today?

NWS SPC‏Verified account @NWSSPC 23s24 seconds ago

 

 

7:56am CDT #SPC Day1 Outlook Slight Risk: from near the northern georgia/alabam... http://go.usa.gov/YWq5 

[SN_Lover]

1 hour ago, Solak said:

Day 3 of slight risk. Nothing to show around here so far. Wondering if the Gulf storms will interfere with moisture transport later today?

NWS SPC‏Verified account @NWSSPC 23s24 seconds ago

 

 

7:56am CDT #SPC Day1 Outlook Slight Risk: from near the northern georgia/alabam... http://go.usa.gov/YWq5 

Storms in Raleigh,  what a joke. Clt has gotten storms almost everyday now. Makes me miss home

[snowlover91]

Well fwiw the HRRR has done well each day with depicting the "no show" of storms across our area contrary to the SPC and other models. Today it actually shows some strong storms in the area so I think we have a good chance. 

[Solak]

NWS Newport/Morehead‏Verified account @NWSMoreheadCity 1h1 hour ago

 

 

After a quiet evening, storms will move back into eastern NC after 11 pm. Some storms could be strong. Here's the forecast radar at 2 am.

[a5ehren]

Looking at these cells on radar, things would be popping off if there were any kind of shear. Kinda funny how that happens.

[downeastnc]

The cell SE of Southern Pines NC sure looks like it has hooked out, there is a fair amount of rotation with it but its still broad at the moment....has had a nasty hail core from time to time though surprised it doesnt have at least a STW on it.