Major Severe Weather Outbreak November 17

[Hoosier]

Terrifying to think about.

 

mxuphl_f34_1200UTC_20131116.gif

 

That seems kinda slow though I've noticed that about that model.

[A-L-E-K]

For the heck of it I compared 12Z NAM values to the SPC Sig Tor Climatology for Northern Indiana.

 

This is what I got. Tomorrow's values at 18Z are plotted by the yellow arrow. 

 

WxStory.png

 

 

wow

[hm8]

New outlook expanded a bit North and West

 

 

...OH VALLEY INTO THE SRN GREAT LAKES...
OVERNIGHT STORMS MAY BE CONTINUING FROM PARTS OF THE OH VALLEY SWWD
ACROSS THE MID-SOUTH/TN VALLEY IN ASSOCIATION WITH A WEAK SHORTWAVE
TROUGH AND LOW LEVEL WARM ADVECTION. THIS ACTIVITY MAY CONTAIN A
MORE LIMITED SEVERE THREAT FOR HAIL AND STRONG/SEVERE WIND GUSTS AS
IT SHIFTS EWD/NEWD WITH TIME. ALTHOUGH DYNAMIC FORCING FOR LARGE
SCALE ASCENT IS EXPECTED TO REMAIN PRIMARILY NORTH OF THIS
AREA...SUFFICIENT DEEP LAYER SHEAR WILL SUPPORT ORGANIZED STORM
STRUCTURES INCLUDING POTENTIAL FOR ISOLATED SUPERCELLS.

THE PRIMARY SEVERE THREAT IS EXPECTED TO DEVELOP DURING THE LATE
MORNING INTO EARLY/MID AFTERNOON FROM ERN IA INTO PARTS OF
NRN/CENTRAL IL...THEN SPREAD EWD THROUGH THE OVERNIGHT HOURS ACROSS
THE GREAT LAKES AND OH VALLEY. STRONG SSWLY LOW LEVEL WINDS WILL
CONTINUE TO ADVECT MOISTURE NWD TOWARD THE DEEPENING SURFACE LOW
WITH 60-65F DEW POINTS REACHING AS FAR NORTH AS NRN PARTS OF IL AND
INDIANA. A PLUME OF STEEPER MID LEVEL LAPSE RATES IS FORECAST TO
EXTEND EWD FROM THE CENTRAL PLAINS TOWARD THE SRN GREAT LAKES AND
WILL CONTRIBUTE TO INCREASED INSTABILITY WITH CAPE OF 1000-1500 J/KG
FORECAST ACROSS PARTS OF IL AND INDIANA. STRONG/SEVERE STORMS MAY
DEVELOP AS EARLY AS MID/LATE MORNING OVER PARTS OF ERN IA NEAR THE
SURFACE LOW AND ADVANCING COLD FRONT...THEN INCREASE IN COVERAGE
INTO NRN/CENTRAL IL DURING THE AFTERNOON AS STRONG DYNAMIC FORCING
WITHIN THE LEFT EXIT REGION OF THE MID/UPPER LEVEL JET STREAK
OVERSPREADS THE LOW LEVEL MOISTURE/INSTABILITY AXIS.

FORECAST SOUNDINGS INDICATE DEVELOPMENT OF CLOCKWISE TURNING
LOW-LEVEL HODOGRAPH STRUCTURES IN ASSOCIATION WITH STRONG VEERING
WIND PROFILES. SEVERAL 12Z CONVECTION-ALLOWING MODELS /ESPECIALLY
THE 4 KM WRF-NSSL AND 1.3 KM NAM FIRE NEST/ INDICATE DEVELOPMENT OF
SUPERCELLS ALONG/AHEAD OF THE COLD FRONT ACROSS PARTS OF IL/INDIANA
AND SRN LOWER MI ALONG/AHEAD OF THE STRONGEST EWD SURGE OF THE COLD
FRONT. THESE WILL HAVE A WINDOW OF OPPORTUNITY FROM MID-LATE
AFTERNOON INTO THE EARLY EVENING TO PRODUCE SWATHS OF DAMAGING WIND
GUSTS...SEVERE HAIL AND POSSIBLY SEVERAL TORNADOES /SOME STRONG/.
WITH TIME...CONVECTION IS EXPECTED TO DEVELOP INTO BOWING LINEAR
STRUCTURES AND SPREAD RAPIDLY EWD/NEWD ACROSS THE LOWER GREAT
LAKES/UPPER OH VALLEY WITH THE PRIMARY SEVERE THREAT TRANSITIONING
TO POTENTIALLY WIDESPREAD DAMAGING WIND GUSTS. THE FAST-MOVING
LINES WILL MOVE PROGRESSIVELY INTO LESSER INSTABILITY...HOWEVER
VERTICAL TRANSFER OF STRONG HORIZONTAL MOMENTUM TO THE SURFACE MAY
MAINTAIN A THREAT FOR WIND DAMAGE THROUGH MUCH OF THE OVERNIGHT
HOURS.

[hm8]

SPC mentioned the NAM fire nest and uh...yikes

 

 

 

 

[tornadotony]

That seems kinda slow though I've noticed that about that model.

Model has a slow bias at that range by probably a couple hours.

[Hoosier]

Obviously trying to pinpoint things on the mesoscale for tomorrow is pretty difficult but thinking bigger picture and playing devil's advocate, should overcast be extensive enough to keep temps down then perhaps this threat would be mitigated somewhat.  Having relatively steep mid level lapse rates and such robust dynamics means that getting prime surface heating is not needed.  Temps ending up 2-3 degrees cooler than model output probably wouldn't make much of a difference but maybe 5+ degrees would.

[tornadotony]

Obviously trying to pinpoint things on the mesoscale for tomorrow is pretty difficult but thinking bigger picture and playing devil's advocate, should overcast be extensive enough to keep temps down then perhaps this threat would be mitigated somewhat.  Having relatively steep mid level lapse rates and such robust dynamics means that getting prime surface heating is not needed.  Temps ending up 2-3 degrees cooler than model output probably wouldn't make much of a difference but maybe 5+ degrees would.

<5% chance of that happening.

[Hoosier]

Looking at a lot of forecast soundings throughout Indiana for tomorrow, they are pretty disgusting and consistent with events that have produced strong and even violent tornadoes around here in the past.  

[Quincy]

For the heck of it I compared 12Z NAM values to the SPC Sig Tor Climatology for Northern Indiana.

This is what I got. Tomorrow's values at 18Z are plotted by the yellow arrow.

WxStory.png

This is very telling. Prerty alarming to see those kind of parameters being progged. Even though CAPE is not through the roof, it doesn't need to be. Yikes.

[Indystorm]

I keep thinking of the 11/10/02 Van Wert F-4.  What we are facing tomorrow seems much more extensive in terms of both geography and wind threat with SPC now mentioning the possibility of some strong tornadoes.  I'm amazed that this year's greatest tornadic potential for our subforum region comes in mid November.  I mentioned this to several people at a meeting I had to attend this morning and they went "Huh?   Getting the word out becomes especially serious in situations like this at this time of year.

[Thundersnow12]

[chase_stormz]

il.jpg

 

 

[Superstorm93]

From the SPC 

 

 

We issued a Day 2 Moderate Risk for severe weather on Sunday. Here are past November Day 2 Moderates (since 1998):

 

[Hoosier]

I keep thinking of the 11/10/02 Van Wert F-4.  What we are facing tomorrow seems much more extensive in terms of both geography and wind threat with SPC now mentioning the possibility of some strong tornadoes.  I'm amazed that this year's greatest tornadic potential for our subforum region comes in mid November.  I mentioned this to several people at a meeting I had to attend this morning and they went "Huh?   Getting the word out becomes especially serious in situations like this at this time of year.

 

I think it's particularly concerning in the northern areas in play.  Once you start getting into places like MI, threats of this magnitude at this time of year are very rare.  

[Superstorm93]

WRF-NMM has a massive line of cells that develop near Chicago and continue on eastward 

 

[PatrickSumner]

I keep thinking of the 11/10/02 Van Wert F-4.  What we are facing tomorrow seems much more extensive in terms of both geography and wind threat with SPC now mentioning the possibility of some strong tornadoes.  I'm amazed that this year's greatest tornadic potential for our subforum region comes in mid November.  I mentioned this to several people at a meeting I had to attend this morning and they went "Huh?   Getting the word out becomes especially serious in situations like this at this time of year.

 

The NWS in Louisville just had a conference call and they mentioned this date...11/10/02. 

[Hoosier]

IWX is mentioning tornadoes in their afternoon zone forecasts...

 

[andyhb]

IWX is mentioning tornadoes in their afternoon zone forecasts...

 

Strongest worded discussion I've seen in quite awhile from them.

 

CHANCES FOR A SEVERE WEATHER OUTBREAK SUNDAY AFTN/EARLY EVE CONTINUE

TO LOOK BETTER AND BETTER WITH EACH MODEL RUN. LATEST GUIDANCE HINTS

AT SOME POTENTIAL FOR A BROKEN LINE OF LOW TOPPED DISCRETE

SUPERCELLS TO DEVELOP WITHIN WARM SECTOR BY LATE MORNING OR EARLY

AFTN GIVEN POTENTIAL LOW LVL CONVERGENCE ALONG A PRE-FRONTAL TROUGH

FEATURE WITH NO CAP AS DEEP UVM PLUME OVERSPREADS THE REGION.

THIS WILL DEPEND ON DEGREE OF DESTABILIZATION WHICH REMAINS A

QUESTION MARK AT THIS FORECAST RANGE. ALL MODEL GUIDANCE DEVELOPS

A LINE OF CONVECTION ALONG THE PRIMARY COLD FRONT SUNDAY

AFTN...DEVELOPING OVER NORTHEAST ILLINOIS AND THEN MERGING INTO A

LEWP/QLCS/SQUALL LINE INTO WESTERN PORTIONS OF THE FA BY MID AFTN

AND EASTERN ZONES LATE AFTN/EARLY EVE. HOW SEVERE/WIDESPREAD THIS

CONVECTION ENDS UP WILL BE DEPENDENT ON HOW EFFICIENT THE

NORTHWARD ADVECTION OF INSTABILITY IS WITHIN THE WARM SECTOR.

EXPECTATIONS ARE THAT AT LEAST 700-1000 J/KG OF SBCAPE WILL BE

ATTAINABLE WITH SEVERAL MODELS SUGGESTING UP TO 1500 J/KG.

FLOW/SHEAR/LOW LVL HELICITY IS OFF THE CHARTS WITH A 120-130 KT

MID LEVEL JET MAX NOSING INTO THE AREA. THE EXPECTATION FOR

WEAK/MODERATE DESTABILIZATION AND SUCH A STRONG WIND FIELD (LINE

NORMAL 0-3 KM BULK SHEAR MAGNITUDES APPROACHING 50 KNOTS!) HINT AT

A POTENTIAL HIGH IMPACT SEVERE WX EVENT...WITH RIJ/BOWING SEGMENTS

AND STEEPENING LOW LVL LAPSE RATES AUGMENTING THE POTENTIAL FOR

DAMAGING WINDS AND MESOVORT TORNADOES. LOW LCL`S IN MOIST

ENVIRONMENT AND SLIGHT BACKING OF LOW LEVEL WINDS IN RESPONSE TO

PRESSURE FALLS ALSO SUGGEST AN ELEVATED RISK FOR TORNADOES WITH

0-1 KM SHEAR PUSHING 40 KNOTS. GIVEN THIS ADDED A TOR MENTION TO

THE GRIDS. STAY TUNED AS THIS HAS THE POTENTIAL TO BE A

SIGNIFICANT SVR WX/TORNADO OUTBREAK ACROSS THE LOWER LAKES AND

OHIO VALLEY. OTHERWISE...UNSEASONABLY MILD WITH ADVISORY LEVEL

WIND GUSTS POSSIBLE OUTSIDE OF CONVECTION SUN AFTN/EVE.

[AppsRunner]

 Definitely is not a good sign to see something like this. Eastern IL and Indiana are going to see a ton of action tomorrow afternoon. 

[andyhb]

LOT:

COLD SEASON SEVERE WEATHER IN OUR AREA OFTEN FEATURE SBCAPE OF LESS
THAN 1000 J/KG...YET GUIDANCE CONTINUE TO ADVERTISE SBCAPES
APPROACHING 1500 J/KG SUNDAY AFTERNOON AS POCKET OF VERY COLD AIR
ALOFT MOVES IN WITH 700-500MB LAPSE RATES >8C/KM. THE INSTABILITY
COMBINED WITH THE TYPICALLY STRONG/EXTREME SHEAR WITH DEEP COLD
SEASON CYCLONE RAISES THE THREAT OF A POTENTIALLY DANGEROUS SEVERE
WEATHER EPISODE ACROSS THE REGION. MODEL FORECASTS SUGGEST THAT
THERE WILL BE A FAIRLY BROAD WARM SECTOR SUNDAY AFTERNOON WITH
MODERATE INSTABILITY AND MINIMAL CINH. CERTAINLY THE MOST LIKELY
SCENARIO WOULD BE FOR CONVECTION TO BE FOCUSED ALONG THE COLD FRONT
AND LIKELY GOING LINEAR FAIRLY QUICKLY AFTER INITIATION...BUT WITH
THE POTENTIAL FOR A DEVELOPING LARGE STRONGLY SHEARED AND WEAKLY
CAPPED WARM SECTOR CANNOT RULE OUT SUPERCELLS DEVELOPING AHEAD OF
CONVECTIVE LINE DUE TO LARGE SCALE ASCENT IN LEFT EXIT REGION OF JET
COUPLED WITH MODEST LOW LEVEL THETA-E ADVECTION. INITIAL DEVELOPMENT
OF CONVECTION ALONG THE COLD FRONT COULD ALSO BE SUPERCELLS
BEFORE MORPHING INTO A LINE...IN EITHER OF THESE SCENARIOS POTENTIAL
WOULD EXIST FOR TORNADIC SUPERCELLS. CLIMO SUGGESTS THAT NOVEMBER
TORNADOES IN OUR AREA ARE VERY RARE...BUT WHEN THEY OCCUR THEY ARE
FREQUENTLY STRONG. DAMAGING WIND THREAT WITH CONVECTIVE LINE LOOKS
TO BE QUITE HIGH GIVEN THE ALREADY STRONG FIELDS IN PLACE...WITH
ATTENDANT THREAT OF EMBEDDED MESOVORTEX DEVELOPMENT LEADING TO
ENHANCED WIND DAMAGE AND/OR QLCS TORNADO THREAT.

DEFINITELY WORTH NOTING THAT THERE ARE MANY MESOSCALE VARIABLE THAT
NEED TO FALL INTO PLACE JUST RIGHT TO RESULT IN SIGNIFICANT SEVERE
WEATHER OUTBREAKS. ITS CERTAINLY NOT HARD TO ENVISION MULTIPLE
SCENARIOS WHERE OUR CWA DODGES ANOTHER SEVERE WEATHER BULLET...BUT
CURRENT INDICATIONS ARE THAT A SIGNIFICANT TORNADO/DAMAGING WIND
THREAT COULD DEVELOP SUNDAY EITHER IN OR CLOSE TO OUR AREA. DESPITE
THE UNCERTAINTIES AND BUST POTENTIAL...ENOUGH INGREDIENTS APPEAR TO
BE FALLING INTO PLACE TO REALLY RATCHET UP THE "HYPE" FOR THE
POTENTIAL EVENT. A COUPLE OF THINGS TO CONSIDER ABOUT THIS EVENT IS
THAT IT WOULD BE AN "OUT OF SEASON" EVENT ON THE WEEKEND WHICH COULD
CATCH PEOPLE OFF GUARD. IN ADDITION...THE VERY STRONG WIND FIELDS
WILL RESULT IN AN EXTREMELY FAST WITH BUNKERS FORECAST RIGHT MOVING
STORM MOTION SUGGESTING THE POTENTIAL FOR STORMS TO BE MOVING AT
CLOSE TO 60KT.

[hm8]

Dtx leary about degree of destabilization

BOTH MAX TEMPERATURE POTENTIAL, WHICH COULD APPROACH RECORD

TERRITORY, AND DESTABILIZATION WILL PARTIALLY DEPEND ON CLOUD COVER.

ATTM, CONTINUE TO FAVOR A MORE PESSIMISTIC CLOUD FORECAST GIVEN

AGGRESSIVE LOW-LEVEL MODEL RH FIELDS AND PROBABLE STOUT INVERSION

ASSOCIATED WITH THE 50-60KT LLJ. AS A RESULT, THE THERMODYNAMIC

ENVIRONMENT DURING SUNDAY EVENING'S FROPA SEEMS MOST LIKELY TO BE

CHARACTERIZED BY INCREDIBLE SHEAR AND MARGINAL-AT-BEST INSTABILITY.

THE INABILITY OF SUCH AN ENVIRONMENT TO SUSTAIN ORGANIZED CONVECTION

WOULD LEAD TO CONCERN BEING FOCUSED ALMOST EXCLUSIVELY ON FROPA

ITSELF AND THE ASSOCIATED STRONGLY-FORCED CONVECTION LOCATED

IMMEDIATELY ALONG THE FRONT. CONVECTION IN THIS PREFERRED SCENARIO

WOULD RACE ACROSS THE CWA WITH A FORWARD SPEED OF AROUND 60 MPH AND

WOULD STILL BE EASILY CAPABLE OF TRANSPORTING SEVERE WINDS TO THE

GROUND. WEAK TORNADOES EMBEDDED WITHIN ANY TYPE OF EVOLVING BOW

ECHO/LEWP STRUCTURE ARE OF SECONDARY CONCERN WITH SEVERE HAIL

NEGLIGIBLE/TERTIARY. IT IS WORTH NOTING, HOWEVER, THAT

DESTABILIZATION IS THE KEY FORECAST POINT - AND THE MOST UNCERTAIN

ONE. ANY POTENTIAL FOR GREATER UPDRAFT ORGANIZATION OFFERED BY AN

INCREASE IN POTENTIAL ENERGY WOULD DRASTICALLY RAMP UP SEVERE

POTENTIAL NOT ONLY ALONG THE FRONT BUT ALSO WITHIN LATE AFTN

PRE-FRONTAL/LLJ ACTIVITY. SUCH AN ENVIRONMENT WOULD SUDDENLY BECOME

MUCH MORE CONDUCIVE FOR DEEPER/SUSTAINED CONVECTION AND SUPERCELL

STRUCTURES.

Sent from my HTCONE using Tapatalk

[andyhb]

GRR:

ELEMENTS SEEM TO BE COMING TOGETHER FOR STRONG TO SEVERE STORMS ON
SUNDAY. MAIN FOCUS IS ON THE SEVERE THREAT DURING THIS TIME FRAME.
POTENTIAL IS THERE FOR WIDESPREAD DAMAGING WINDS AND THE THREAT FOR
TORNADOES SUNDAY. MODERATE RISK ACROSS THE BULK OF THE AREA LOOKS
GOOD WITH STRONG WIND FIELDS IN PLACE. 850MB LLJ REACHES 60 KNOTS
WITH MID LEVEL WINDS PUSHING 80 KNOTS AT 500MB/S. 0-6KM BULK SHEAR
EXCEEDS 70 KNOTS. CAPE VALUES ARE FORECAST TO PUSH TOWARD 1000 J/KG
WHICH SEEMS REASONABLE AS I94 DEW POINTS WILL NEAR 60F. DYNAMICS
WITH THE SYSTEMS ARE VERY STRONG AS A NEGATIVE TILT SHORTWAVE TROUGH
DRIVES INTO THE REGION. LEFT EXIT REGION UPPER DIVERGENCE WILL AID
THE CAUSE AS WELL. LOOKING FOR A WARM FRONT TO LIFT INTO THE AREA
SUNDAY MORNING AFTER DAYBREAK WITH A COLD FRONT SWEEPING THROUGH
DURING THE AFTERNOON.

LOOKING AT SIMULATED REFLECTIVITY FROM MESOSCALE MODELS LIKE THE
NSSL WRF AND VIA THE NAM12 IT APPEARS AS THOUGH WE COULD BE LOOKING
AT DISCRETE SUPERCELLS ALONG THE WARM FRONT LIFTING NORTHEAST
THROUGH THE AREA IN THE MORNING FOLLOWED BY A SQUALL LINE SWEEPING
EAST AHEAD OF THE COLD FRONT IN THE AFTERNOON. THE SQUALL LINE WILL
LIKELY FEATURE LINES AND BOWS EMBEDDED IN A BROKEN LINE. ENHANCED
WIND DAMAGE WILL BE POSSIBLE WITH THIS LINEAR ACTIVITY GIVEN THE
WIND FIELDS IN PLACE. GUSTS OVER 70 MPH WILL CERTAINLY BE POSSIBLE.
TORNADOES CANNOT BE RULED OUT GIVEN STRONG LOW LEVEL HELICITY
VALUES. 0-1KM SRH EXCEEDS 300 M2/S2 OVER THE ENTIRE CWA SUNDAY
AFTERNOON. TORNADO THREAT EXISTS REALLY WITH BOTH THE CELLULAR
MORNING ACTIVITY AND EMBEDDED IN THE SQUALL LINE. A HEIGHTENED
AWARENESS WILL BE NEEDED GIVEN THE PARAMETERS COMING TOGETHER ON
SUNDAY.

[Thundersnow12]

Yeah that was a terrific AFD by Gino

[stormtrackertf]

Terrifying to think about.

 

mxuphl_f34_1200UTC_20131116.gif

 

 

SPC mentioned the NAM fire nest and uh...yikes

 

 

 

 

I try not to buy into hype much (maybe even to a fault) but I can't help but feel in my gut this isn't going to end well for some people.

[Chargers09]

It really seems like DTX has never bought into the event fully, but it's nice to see them at least starting to recognize the enhanced threat of severe weather in the latest AFD. 

[Central Illinois]

ILX with some strong wording:

The second stronger wave is expected to come out of the plains on

Sunday with rapid cyclogenesis over Iowa and Missouri prior to sunrise.

Strong 140+ kt jet currently plunging down the Pacific Coast is

expected to round the base of the trough on Sunday and in

combination with the strong low-level jet produce extremely strong

shear. The intensifying low pressure system is expected to be

crossing southern Wisconsin by Midday with a trailing cold front

extending southward near the Illinois river. As the strong cooling

aloft and the surface cold front encounters the preexisting low-

level jet and boundary layer moisture, thunderstorms will initiate

along the boundary, and possibly in the high moisture air ahead of

the system.

The primary severe weather threat with the front will be strong

and damaging once the convection organizes as momentum is brought

to the surface by the storm. Wild card is the potential for discrete

cells before the line develops and out ahead of the line. Any

discrete cells will be able to quickly spin given the tremendous

amounts of shear being tapped. Can not rule out tornadoes,

possibly strong, in this scenario, Particularly across eastern

forecast area.

The system will move very quickly eastward as the upper jet rounds

the base of the trough. Front and accompanying severe weather

threat will likely be into Indiana by 7 pm or so.

[snowlover2]

ILN finally got their AFD out.

 

 

 

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
A STRONG LOW PRESSURE SYSTEM WILL APPROACH THE AREA ON SUNDAY.
WINDS WILL PICK UP DURING THE DAYTIME HOURS WITH GUSTY WINDS
EXPECTED THROUGH THE DAY AND INTO SUNDAY NIGHT. THE BEST CHANCE
FOR THE STRONGER WIND GUSTS WILL BE WITH THE COLD FRONT IN THE
EVENING HOURS. MODELS ARE INDICATING PRETTY EXTENSIVE CLOUD COVER
ACROSS THE FA DURING THE DAYTIME HOURS ON SUNDAY HOWEVER IF THERE
AREA SOME BREAKS IN THE CLOUDS A FEW WIND GUSTS COULD APPROACH
WIND ADVISORY CRITERIA DURING THE DAY AS WELL. WITH THIS IN MIND
DECIDED TO GO WITH A WIND ADVISORY STARTING AT 15Z ON SUNDAY AND
CONTINUING ACROSS THE AREA THROUGH 05Z.

STRONG SOUTHERLY FLOW ON SUNDAY WILL ALLOW TEMPERATURES TO RISE
INTO THE 60S TO AROUND 70. THE POTENTIAL EXISTS FOR SOME LOCATIONS
ACROSS THE SOUTHERN PORTIONS OF THE FA TO EVEN REACH INTO THE LOW
TO MIDDLE 70S IF THERE ARE SOME BREAKS IN THE CLOUDS. AT THIS
POINT DECIDED TO GO AROUND 70 DEGREES IN THE SOUTH.

PRECIPITATION WILL BE ONGOING AT THE BEGINNING AT THE BEGINNING OF
THE SHORT TERM TIME PERIOD HOWEVER EXPECT THIS PRECIPITATION TO
TAPER OFF FROM WEST TO EAST THROUGH THE MORNING HOURS. A FEW
ISOLATED EMBEDDED THUNDERSTORMS WILL BE POSSIBLE DURING THE
MORNING HOURS ON SUNDAY WITH SOME MINIMAL INSTABILITY PRESENT.

THERE WILL BE A DECREASE AND IN SOME LOCATIONS A LULL IN THE
PRECIPITATION ACROSS THE FA DURING THE MID DAY AND EARLY AFTERNOON
HOURS.

THE FOCUS THEN SHIFTS TO THE SEVERE POTENTIAL LATE SUNDAY
AFTERNOON INTO SUNDAY NIGHT AS A STRONG COLD FRONT APPROACHES AND
THEN MOVES THROUGH THE FA. THE FIRST THREAT WOULD BE ANY ACTIVITY
THAT DEVELOPS OUT AHEAD OF THE MAIN LINE AND THEN THERE WILL BE
SECOND THREAT WHEN THE LINE OF CONVECTION MOVES THROUGH THE FA.
SPC HAS THE ENTIRE FA IN A MODERATE RISK FOR SUNDAY. INSTABILITY
INCREASES ACROSS THE FA DURING THE LATE AFTERNOON HOURS INTO THE
EARLY EVENING HOURS.

THERE IS THE POTENTIAL THAT SOME SCATTERED THUNDERSTORM ACTIVITY
MAY DEVELOP AHEAD OF THE LINE ON SUNDAY. THERE ARE ALSO
INDICATIONS THAT A FEW SUPERCELLS WILL BE POSSIBLE WITH THE
HIGHEST THREAT OF THIS ACROSS NW PORTIONS OF THE FA. A COLD FRONT
WILL APPROACH THE AREA DURING THE EVENING HOURS AND EXPECT A LINE
OF STORMS TO MOVE THROUGH DURING THIS TIME. WITH THE STRONG LOW
LEVEL WIND FIELDS DAMAGING WINDS APPEAR LIKELY. IN ADDITION TO
THE DAMAGING WIND THREAT A FEW TORNADOES WILL ALSO BE POSSIBLE
WITH THE LINE. AN ISOLATED TORNADO THREAT IS ALSO POSSIBLE IF
THERE IS ANY SUPERCELL DEVELOPMENT AHEAD OF THE LINE. CIPS ANALOGS
AGREE THAT THIS PATTERN IS INDICATIVE OF A DAMAGING WIND THREAT
AND ISOLATED TORNADO THREAT. CONTINUED TO HIGHLIGHT THESE THREATS
IN THE HWO AND KEPT THE SEVERE WORDING IN THE FORECAST.

IN ADDITION TO THE SEVERE THREAT WILL BE THE THREAT FOR HEAVY RAIN
SUNDAY EVENING WITH SOME OF THE STORMS. ALTHOUGH HEAVY RAIN WILL
BE POSSIBLE AM NOT EXPECTING A LARGE FLOODING ISSUE DUE TO THE
PROGRESSIVE NATURE OF THE SYSTEM.

THE COLD FRONT WILL MOVE THROUGH SUNDAY EVENING INTO SUNDAY NIGHT.
PRECIPITATION WILL THEN TAPER OFF ACROSS THE FA. WIND GUSTS WILL
ALSO DECREASE AFTER MIDNIGHT.

EXPECT DRY CONDITIONS ACROSS THE FA ON MONDAY WITH HIGH PRESSURE
SLOWLY WORKING INTO THE FA. KEPT MONDAY DRY FOR NOW HOWEVER WITH
WINDS OFF OF THE LAKE DID INCREASE CLOUD COVER ACROSS THE
AREA...ESPECIALLY ACROSS THE NORTH. WITH COOLER AIR WORKING INTO
THE REGION TEMPERATURES WILL STRUGGLE TO RISE ON MONDAY WITH HIGH
TEMPERATURES ONLY IN THE MIDDLE 40S TO LOW 50S. SKIES WILL BEGIN
TO CLEAR OUT MONDAY NIGHT ALLOWING TEMPERATURES TO FALL INTO THE
UPPER 20S TO LOW 30S.

 

[YHM Supercell]

For the Ontario posters here...looks more and more likely with each model run that a sustained fast moving squall line will push into SW ON tomorrow evening and continue eastward from there. Tornado threat will likely be very low here given the lack of instability, but there is always the chance for QLCS type tor's with these squall lines well into the overnight. Extreme shear and mid/upper level winds will promote an enhanced risk of damaging winds for areas of SW/SC ON. Many hi-res solutions have a well organized squall line pushing through SW ON and SC ON including the GTA. Should be interesting to watch this event unfold.

[Thundersnow12]

You can't chase tornadic supercells moving at 60kts.

[Chinook]

They issued a mesoscale discussion for the Kansas City area tonight (0305 PM CST SAT NOV 16 2013)

 

Note: significant tornado parameter could be up to 1 or 2 near Kansas City (see mesoanalysis at +2 hours and +4 hours) Convective inhibition seems to be pretty low now.