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Major Severe Weather Outbreak November 17

Hoosier

By Hoosier,
in Weather Forecasting and Discussion

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extremewx52

extremewx52

Posted
Posted

I may be driving...oh...5 miles or so. :P

 

I think you may be on to something there IWXwx. Risk area is narrowing and we continue to look like we are in the hot spot. A typical location for severe weather around here is on the nose of the 500 mb jet. The range of the 500 jet nose at 21Z sunday is the southern tip of lake Michigan (NAM) to Indianapolis (ECMWF.)

 

Here is the GFS aiming right at ya.

 

post-8696-0-28286900-1384517902_thumb.pn

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weatherwiz

weatherwiz

Posted
Posted

Sfc winds across the entire length and width of Indiana at 21z Sunday on the Euro are 180-185 deg...that'll play...that'll play big time.

 

I would have to think that in the end (if everything were to play out as modeled right now) sfc winds would be much more backed than what models are showing right now, especially in the vicinity of the warm front.  Seeing the models having a LLJ at 850 approaching 65 knots punching into the core of the warm sector with SBcape projections of near 500 J/KG and LI values -2C or -3C or so and a strengthening nose of the MLJ is quite alarming.  

 

One thing to watch out for is with winds aloft so potent updrfats may not have enough upward momentum to really grow tall enough, however, if some of these instability parameters play out along with extra forcing from the MLJ/ULJ that may not be a problem.  700mb omega values increase throughout the day as well using the SPC SREF probs.  

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Bryan Wood

Bryan Wood

Posted
Posted

I'm still on the fence about chasing Sunday. I think the best tor threat areas are likely SE IL/SW IN, but with heavily forested areas and few crossings of the Wabash River, it's a no go area for me. May try west of US 31/north of I-70/74 in IN if things look like they may pan out during daylight. Of course, the other consideration is getting caught in the subsequent QLCS on the drive back to Ohio, which I don't want any part of.

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OceanStWx

OceanStWx

Posted
Posted

Euro looks close to previous runs, maybe a tad faster.  Threat still looks to extend even down here Sunday night.  I'd say IN is probably the highest threat area, and yeah, I mean the whole state more or less.

 

Definitely agree here, right on the intersection of the instability axis and jet core.

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harrisale

harrisale

Posted
Posted

I trust that IWX will play up the severity of this well for this time of year.  I see they have a good heads up on their webpage at present. The 500 and 300 mb jets are quite scary.  Get those 60 degree dews and some sunshine and we're in business.

 

SPC discussion from this morning mentions that cloud cover and showers will be likely in the warm sector so this could certainly limit the threat (somewhat) and as weatherwiz mentioned prevent updrafts from gaining significant strength.

 

 

 SPC AC 150830

   DAY 3 CONVECTIVE OUTLOOK 

   NWS STORM PREDICTION CENTER NORMAN OK

   0230 AM CST FRI NOV 15 2013

   VALID 171200Z - 181200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE TN AND OH

   VALLEYS AND GREAT LAKES AREAS...

   ...SYNOPSIS...

   A SHORTWAVE TROUGH WITH ATTENDANT STRONG UPPER JET EMBEDDED WITHIN

   BASE OF THE SYNOPTIC TROUGH WILL EJECT NEGATIVELY TILTED THROUGH THE

   MID MS AND OH VALLEYS SUNDAY...REACHING A PORTION OF THE NERN U.S.

   TOWARD THE END OF THE PERIOD. THIS FEATURE WILL INDUCE A SFC CYCLONE

   THAT IS FORECAST TO UNDERGO SIGNIFICANT DEEPENING AS IT MOVES NEWD

   FROM THE UPPER MS VALLEY INTO THE GREAT LAKES SUNDAY AFTERNOON. COLD

   FRONT TRAILING FROM THE LOW WILL SWEEP THROUGH THE MID MS...OH AND

   TN VALLEYS...WHILE A WARM FRONT LIFTS NWD THROUGH THE OH VALLEY AND

   GREAT LAKES.

   ...OH AND TN VALLEY REGIONS...

   A STRONG 50+ KT SWLY LLJ WILL ADVECT PARTIALLY MODIFIED GULF AIR

   WITH DEWPOINTS IN THE UPPER 50S TO LOW 60S INTO THE OH VALLEY AND

   GREAT LAKES REGION WITH MID 60S LIKELY FARTHER SOUTH ACROSS THE TN

   VALLEY AREA. THE MOISTURE RETURN WILL BE ACCOMPANIED BY WIDESPREAD

   CLOUDS THAT WILL LIMIT DIABATIC HEATING OF THE BOUNDARY LAYER IN

   MUCH OF PRE-FRONTAL WARM SECTOR. MOREOVER...AREAS OF SHOWERS AND A

   FEW THUNDERSTORMS WILL PROBABLY BE ONGOING OVER A PORTION OF THE OH

   VALLEY WARM SECTOR. THUS THE PRIMARY DESTABILIZATION MECHANISM WILL

   PROBABLY BE MOISTURE ADVECTION...BUT SFC BASED INSTABILITY WILL

   LIKELY REMAIN SOMEWHAT MARGINAL /MLCAPE AOB 500 J/KG/...ESPECIALLY

   WITH NWD AND EWD EXTENT INTO THE OH VALLEY AND GREAT LAKES.

   NEVERTHELESS...THE DEEPENING CYCLONE WILL BE ACCOMPANIED BY AN

   INCREASE IN FRONTOGENETIC FORCING ALONG THE COLD FRONT SWEEPING EWD

   THROUGH THE OH VALLEY. STORMS MAY INCREASE DURING THE DAY ALONG

   PRE-FRONTAL WARM CONVEYOR BELT BENEATH DIFFLUENT UPPER JET EXIT

   REGION. OTHER STORMS WILL INITIATE ALONG STRENGTHENING COLD FRONT.

   POTENTIAL WILL EXIST FOR PRE-FRONTAL STORMS TO DEVELOP SUPERCELL

   STRUCTURES GIVEN STRENGTH OF VERTICAL SHEAR AND SIZE OF HODOGRAPHS

   ALONG LLJ...BUT EXTENT OF ANY TORNADO THREAT WILL DEPEND ON DEGREE

   OF BOUNDARY LAYER DESTABILIZATION. OTHERWISE...STORMS WILL LIKELY

   EVOLVE INTO LINES ALONG THE COLD FRONT WITH A THREAT FOR WIDESPREAD

   DAMAGING WIND AS THE ACTIVITY DEVELOPS EWD THROUGH THE OH AND TN

   VALLEY REGIONS.

   ...NY AND PA...

   STORMS WILL EVENTUALLY OUTPACE THE MOIST AXIS SUNDAY NIGHT AND

   ENCOUNTER MUCH WEAKER INSTABILITY AS THEY APPROACH THE NERN STATES.

   HOWEVER...AT LEAST A MODEST THREAT FOR ISOLATED DAMAGING WIND WITH

   REMAINING LOW TOPPED CONVECTION CANNOT BE RULED OUT LATE THIS

   PERIOD.

 

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harrisale

harrisale

Posted
Posted

Ontario-wise, SPC extends the 30% risk area well into Southern Ontario. The majority of this risk will likely be wind damage as instability will struggle this far north to produce any real robust updrafts for rotation. CAPE will have trouble pushing over 500 J/kg although some instability will remain after the sun goes down.

 

qgbb3.gif

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OceanStWx

OceanStWx

Posted
Posted

SREF_prob_combined_sigtor__f060.gif

 

I find it interesting that the latest SREF run has this dual-area threat. Peeking at the CIPS analog page, you can see this plays out in the top analog storm reports.

 

SVRgfs212F072.png

 

Many of the individual top analogs look this way as well, with a cluster of reports near the surface low/warm front, and another cluster in the Southeast (on what is likely the leading edge of the deep moisture).

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extremewx52

extremewx52

Posted
Posted

Yeah, this thing may get started earlier than expected...I'd caution people using an early frontal passage as a reason for a lesser threat.  Diabatic heating's role in this may not be that great to begin with anyway...

 

Exactly. Moisture advection will be the primary destabilization factor. Any diabatic heating will just add fuel to the already burning fire. 

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weatherwiz

weatherwiz

Posted
Posted

Holy cow is the 12z NAM quite scary.  Generating SBcape values upwards of 1000 J/KG with LI values as low as -4C to -5C with a LLJ in the warm sector approaching 60 knots and even showing 120-125 kt 500mb jet streak showing up.  It's much more impressive with moisture return and not sure if perhaps dews are slightly underdone but regardless, given the level of cold air heading into the mid levels and at least adequate moisture return, the NAM mau not be far off with it's projected instability values.

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Hoosier

Hoosier

Posted
  • Author
Posted

Yeah, this thing may get started earlier than expected...I'd caution people using an early frontal passage as a reason for a lesser threat. Diabatic heating's role in this may not be that great to begin with anyway...

Great point. It's very possible this gets going in the morning hours. Surface based instability already looks good by then.

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Gilbertfly

Gilbertfly

Posted
Posted

Great point. It's very possible this gets going in the morning hours. Surface based instability already looks good by then.

 

SREF has been advertising this for quite a few runs now....at least in regards to aspects closer tied to the LP

 

I am far from an expert on this stuff though...so the thing I was wondering is if Saturday night convection washes things out a bit or not (again, in terms of things further north closer to the LP)

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Jim Marusak

Jim Marusak

Posted
Posted

Holy cow is the 12z NAM quite scary.  Generating SBcape values upwards of 1000 J/KG with LI values as low as -4C to -5C with a LLJ in the warm sector approaching 60 knots and even showing 120-125 kt 500mb jet streak showing up.  It's much more impressive with moisture return and not sure if perhaps dews are slightly underdone but regardless, given the level of cold air heading into the mid levels and at least adequate moisture return, the NAM mau not be far off with it's projected instability values.

the talk about a day or so ago was that the moisture return wasn't going to be as much as the models are projecting. now we're starting to talk that the moisture return is being a bit underdone? wow. but yea, the Canadian regional runs are even hinting at dew points approaching 50 in the twin cities. Add that to the 12Z GFS which is continuing the trend, with the dynamics above, and I am also worried a bit for tomorrow in IA, WI, IL, and MO, more than the current "see text" issued. we are starting to converge on the solution in this morning's runs, and like everyone is saying, I am getting a bit concerned here for Sunday, mainly from a wind threat standpoint.

 

canadian regional severe wx parameters 36hr panel, then 48 hr below that

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_SUMRSVRWX_036.jpg

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_SUMRSVRWX_048.jpg

 

same model, low level winds and moisture, 36 and 48 panels

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_LOLVLWIND_036.jpg

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_LOLVLWIND_048.jpg

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weatherwiz

weatherwiz

Posted
Posted

Early starts are far from unprecedented this time of year.  Just think about 10/26/10, 12/31/10, etc...if you already have this anomalous of an airmass needed to feed this stuff, how much can diabatic heating really matter?

 

This is absolutely true.  This time of year, when we start getting more into the cold season setups, dynamics/kinetics play a much larger role than thermodynamics...not that thermodynamics aren't important but they can be compensated for.  

 

At this juncture earlier timing would favor more in the way of perhaps discrete activity with then everything progressing into a more linear mode and probably some weakening as the activity slides east of OV

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weatherwiz

weatherwiz

Posted
Posted

the talk about a day or so ago was that the moisture return wasn't going to be as much as the models are projecting. now we're starting to talk that the moisture return is being a bit underdone? wow. but yea, the Canadian regional runs are even hinting at dew points approaching 50 in the twin cities. Add that to the 12Z GFS which is continuing the trend, with the dynamics above, and I am also worried a bit for tomorrow in IA, WI, IL, and MO, more than the current "see text" issued. we are starting to converge on the solution in this morning's runs, and like everyone is saying, I am getting a bit concerned here for Sunday, mainly from a wind threat standpoint.

 

canadian regional severe wx parameters 36hr panel, then 48 hr below that

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_SUMRSVRWX_036.jpg

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_SUMRSVRWX_048.jpg

 

same model, low level winds and moisture, 36 and 48 panels

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_LOLVLWIND_036.jpg

 

http://weather.gc.ca/data/prog/regional/2013111512/2013111512_054_R1_north@america_I_4PAN_LOLVLWIND_048.jpg

 

Moisture return this time of year can be very, very tricky but it's appearing that moisture return may not really be a big issue at all.  Especially considering the region will be under a southerly flow for over a day and the moisture (higher dews) aren't all that too far south from the region.

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Hoosier

Hoosier

Posted
  • Author
Posted

Early starts are far from unprecedented this time of year. Just think about 10/26/10, 12/31/10, etc...if you already have this anomalous of an airmass needed to feed this stuff, how much can diabatic heating really matter?

I was thinking about 10/26/10 a little while ago and how unusual it is to get a tornado outbreak to initiate N of the OH River during the early morning hours. It just doesn't happen very much, but anomalous setups can produce anomalous results.

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snowlover2

snowlover2

Posted
Posted

Slight risk area added for tomorrow.

 

 

 

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CST FRI NOV 15 2013

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE MO
VALLEY AND MIDDLE/UPPER MS RIVER VALLEY...

...MIDDLE/LOWER MO VALLEY TO MIDDLE/UPPER MS RIVER VALLEY...
AN AMPLIFYING/PROGRESSIVE UPPER TROUGH AND INTENSIFYING POLAR JET
WILL GENERALLY SPREAD EAST-SOUTHEASTWARD OVER THE NORTHERN ROCKIES
AND MUCH OF THE NORTHERN/CENTRAL PLAINS TO MIDWEST SATURDAY AND
SATURDAY NIGHT. IN ASSOCIATION WITH A LEAD SHORTWAVE TROUGH AND/OR
LEADING EDGE OF HEIGHT FALLS...SURFACE CYCLOGENESIS IS EXPECTED TO
OCCUR IN EARNEST SATURDAY NIGHT INTO EARLY SUNDAY OVER THE UPPER
MIDWEST. MEANWHILE...AIRMASS MODIFICATION WILL CONTINUE TO OCCUR
WITH MOIST ADVECTION CONTRIBUTING TO AN INCREASINGLY PREVALENT
CORRIDOR OF UPPER 50S/LOWER 60S F SURFACE DEWPOINTS SATURDAY NIGHT
TO THE EAST OF THE AFOREMENTIONED SURFACE LOW AND A COLD FRONT.

INITIALLY...ELEVATED SHOWERS/TSTMS ARE LIKELY TO OCCUR SATURDAY
MORNING INTO AFTERNOON ACROSS PORTIONS OF THE UPPER MIDWEST/UPPER MS
RIVER VALLEY. WHILE A FEW STRONGER STORMS CAPABLE OF SOME HAIL
CANNOT BE ENTIRELY RULED OUT...THE RELATIVELY MORE PROBABLE SEVERE
RISK SHOULD NOT OCCUR UNTIL SATURDAY NIGHT. REGARDING SATURDAY
NIGHT...THE EXACT TIMING/QUALITY OF THE NORTHWARD FLUX OF LOW-LEVEL
MOISTURE IS A KEY QUESTION...BUT AT LEAST SOME EVENING/OVERNIGHT
SEVERE RISK SHOULD EXIST GIVEN INCREASING MOISTURE AND THE ARRIVAL
OF STRONGER FORCING FOR ASCENT. CURRENT THINKING IS THAT ELEVATED
STORMS CAPABLE OF SEVERE HAIL WOULD BE THE MOST PROBABLE CONCERN
SATURDAY NIGHT ESPECIALLY IN/NEAR THE SLIGHT RISK. THAT
SAID...SUFFICIENT LOW-LEVEL MOISTURE MAY BE IN PLACE BY THE
EVENING/OVERNIGHT HOURS FOR THE POSSIBILITY OF AT LEAST SOME NEAR
SURFACE-BASED STORMS ACROSS PORTIONS OF IA/MO. SHOULD THIS BE THE
CASE...DAMAGING WINDS/ISOLATED TORNADO RISK WOULD BE POSSIBLE.

...OZARKS VICINITY...
FARTHER SOUTH...THE SEVERE WEATHER POTENTIAL THROUGH 12Z SUNDAY
APPEARS EVEN MORE CONDITIONAL ACROSS AREAS SUCH AS SOUTHERN
MO/NORTHERN AR AND THE ADJACENT MS RIVER VALLEY VICINITY. STEADILY
INCREASINGLY LOW-LEVEL MOISTURE COULD BECOME SUFFICIENT TO SUPPORT
AT LEAST NEAR SURFACE-BASED STORMS LATE SATURDAY NIGHT/EARLY SUNDAY.
GIVEN A HIGHLY SHEARED ENVIRONMENT...THIS REGION WILL BE CLOSELY
REEVALUATED FOR DAMAGING WIND/ISOLATED TORNADO POTENTIAL AND A
POSSIBLE EXPANSION OF THE CATEGORICAL SLIGHT RISK.
 

 

post-4544-0-19200500-1384536987_thumb.gi

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Memphis Weather

Memphis Weather

Posted
Posted

More adding to the continuing discussion at this point, but looking over the latest data today, still seeing distinct differences between the primary three: NAM, GFS and Euro. Nevertheless, all continue to point towards IL/IN/OH/KY as the focal point for severe weather Sunday. SPC's 30% area delineates that pretty well overall, except I would personally trim the TN portion. I remain doubtful on anything worthwhile once you get into TN/MS/AL, as the primary forcing mechanisms remain to the north, along with the cooler mid-level temperatures (thus a better thermodynamic-kinematic balanced environment). Wouldn't rule out some spotty damaging winds, maybe a tornado *if* convection manages to fire late, but the confidence is very low for these areas.

 

Back to the main focus, it seems a swath of discrete supercells could begin rather early in the day over IL (perhaps a continuation of Saturday's events if the latest SWODY2 pans out), congealing by evening into a more widespread QLCS in the eastern OH Valley. If boundary layer conditions are favorable, and data suggests it will, several tornadoes could occur from IL into IN with this activity. The amount of destabilization is being fed nearly solely on the impressive mid-level temperature profile and combined with a moist boundary layer and of course impressive shear profile, this spells trouble for any discrete cells that move through this environment. As the activity develops and spreads into OH/KY, damaging winds become the greater threat into the night, but spin-ups would be a secondary threat very similar to what unfolded in the KPAH region Halloween evening.

 

I'm not sure how to qualify this in terms of outbreak potential, I know 11/10/02 has been thrown around a lot, but that's a very high bar to set, especially considering the southern extent of it which again doesn't appear likely in this setup. Still, for those in the OH Valley, the ceiling *potential* is certainly greater than Halloween and likely in the higher tier possible within November for this region.

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OceanStWx

OceanStWx

Posted
Posted

I have 28 dew point currently this Friday afternoon with 50 degree dews confined to the upper regions of the Gulf States.  It will indeed be amazing to have the moisture pumped northward of the Ohio Valley into IN and Ohio as models prog for Sunday.

 

It might be hard to keep the developing warm sector cloud free, but if it can last that way overnight you should be able to track that moisture return on the IR satellite. The deeper moisture will remain warmer (thus darker on IR) as it moves northward.

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