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November 11th-12th storm system


Thundersnow12

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GFS forecast soundings would indicate some high wind warning criteria possibilities for northern IL early Thu.  The soundings indicate mixing up to about 900mb, where winds are in the 55-60kt range.  That's 60-70mph just off the deck.  Considering unidirectional wind profiles, mixing up to around 900mb, and possible precipitation helping to bring down some higher momentum air I think a 2-4hr period of warning criteria winds are quite possible over eastern IA and northern IL Thursday morning.

 

 

Not quite like the GFS runs from a few days ago but still pretty nice.  I'm hoping for stronger ticks as we get closer. 

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00z RGEM is out for Wed. 4mb deeper than the NAM.

 

RGEM did well last year in calling for a slightly stronger storm than some of the others had forecast.  Wouldn't be surprised to see this thing come in even deeper on subsequent runs given the tremendous kinematics.  GFS has ticked a little stronger tonight compared to the past several runs.  NAM will probably catch up and come in deeper as well the next few runs.

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Even in November 1998, ORD had 40+ mph gusts from about 7 AM on the 10th to about 4 AM on the 11th.

There's that event, and then Octobomb too. That had two periods of winds around or well over 40mph, which when combined added up to around 24hrs.

So this event looks to have a higher ceiling length wise, but we'll see how it goes.

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For posterity the Day 2 text:

 

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CST TUE NOV 10 2015

VALID 111200Z - 121200Z

...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF SRN IA...MO AND
IL...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE GREAT
PLAINS...MS VALLEY...ARKLATEX...OH VALLEY AND TN VALLEY OUTSIDE THE
ENHANCED RISK AREA...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE GREAT
PLAINS...UPPER MIDWEST...MS VALLEY...LOWER MS VALLEY...OH VALLEY AND
TN VALLEY OUTSIDE THE SLIGHT RISK AREA...

...SUMMARY...
SEVERE THUNDERSTORMS CAPABLE OF LARGE HAIL AND WIND DAMAGE ARE
EXPECTED TO DEVELOP IN THE CENTRAL PLAINS AND LOWER TO MID MISSOURI
VALLEY LATE WEDNESDAY MORNING INTO EARLY AFTERNOON. THE POTENTIAL
FOR WIND DAMAGE AND TORNADOES SHOULD INCREASE DURING THE AFTERNOON
ACROSS THE MID MISSISSIPPI VALLEY REACHING THE OHIO VALLEY DURING
THE EARLY EVENING. A MORE ISOLATED THREAT FOR LARGE HAIL...WIND
DAMAGE AND TORNADOES WILL ALSO BE POSSIBLE DURING THE AFTERNOON
ACROSS THE ARKLATEX...OZARKS AND LOWER MISSISSIPPI VALLEY.

...CNTRL PLAINS/MID MS VALLEY/LOWER TO MID MO VALLEY/OH VALLEY...
A VIGOROUS UPPER-LEVEL TROUGH WILL MOVE QUICKLY EWD ACROSS SRN
ROCKIES TUESDAY NIGHT AND INTO THE CNTRL HIGH PLAINS WEDNESDAY
MORNING. AN UPPER-LEVEL LOW IS FORECAST TO CLOSE OFF OVER THE CNTRL
HIGH PLAINS AS AN IMPRESSIVE 90 TO 110 KT MID-LEVEL JET MOVES
QUICKLY ENEWD ACROSS THE SRN AND CNTRL PLAINS. THE EXIT REGION OF
THE MID-LEVEL JET AND THE ASSOCIATED STRONG LARGE-SCALE ASCENT WILL
OVERSPREAD THE LOWER AND MID MO VALLEY. THIS WILL COINCIDE WITH
DEVELOPMENT OF A POCKET OF INSTABILITY IN NE KS...FAR SE NEB...SWRN
IA AND NW MO WHERE THUNDERSTORM DEVELOPMENT SHOULD TAKE PLACE DURING
THE LATE MORNING AND EARLY AFTERNOON. THIS ACTIVITY SHOULD QUICKLY
EXPAND IN COVERAGE DURING THE AFTERNOON AND MOVE EWD INTO THE MS AND
OH VALLEYS DURING THE LATE AFTERNOON AND EARLY EVENING.

FORECAST SOUNDINGS WEDNESDAY AFTERNOON ACROSS THE ENHANCED THREAT
AREA FROM NRN MO INTO WRN IL SHOW SFC DEWPOINTS NEAR 60 F WITH
MLCAPE NEAR 500 J/KG. 0-6 KM SHEAR IS EXPECTED TO BE FROM 70 TO 85
KT WITH VERY STRONG SPEED SHEAR FROM THE SFC TO 850 MB. THIS
ENVIRONMENT COMBINED WITH A FAST EWD MOVEMENT OF STORMS SHOULD BE
FAVORABLE FOR DAMAGING WIND GUSTS WITH CELLS ALONG THE FRONT. AN
ENHANCED WIND DAMAGE THREAT SHOULD DEVELOP AS LARGER-SCALE LINE
SEGMENTS ORGANIZE. DIRECTIONAL SHEAR IN THE LOW-LEVELS WILL ALSO
SUPPORT STORM ROTATION. DISCRETE CELLS THAT DEVELOP EARLY IN THE
EVENT OR WITH CELLS THAT CAN REMAIN DISCRETE AHEAD OF THE FRONT
SHOULD BE ACCOMPANIED BY A TORNADO THREAT. THE TORNADO THREAT IS
EXPECTED TO BE GREATEST FROM SRN IA SWD INTO CNTRL MO AND EWD INTO
SRN AND CNTRL IL JUST TO THE WEST OF A FOCUSED 55 TO 65 KT LOW-LEVEL
JET. A STRONG TORNADO OR TWO WILL BE POSSIBLE ALONG THIS CORRIDOR.

...SRN PLAINS/ARKLATEX/LOWER MS VALLEY/TN VALLEY...
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE INTO THE SRN PLAINS ON
WEDNESDAY AS A LOW-LEVEL JET STRENGTHENS ACROSS THE ARKLATEX AND
LOWER TO MID MS VALLEY. THIS WILL RESULT IN MOISTURE ADVECTION
DURING THE DAY ACROSS EAST TX...LA AND AR. IN ADDITION...SFC HEATING
SHOULD ENABLE INSTABILITY TO INCREASE AHEAD OF A FAST MOVING COLD
FRONT. SCATTERED THUNDERSTORM DEVELOPMENT WILL LIKELY TAKE PLACE
DURING THE AFTERNOON ALONG THE FRONT FROM AR SSWWD INTO EAST TX AND
NRN LA. THIS ACTIVITY SHOULD MOVE EWD INTO THE LOWER MS VALLEY
DURING THE LATE AFTERNOON AND EARLY EVENING.

AFTERNOON FORECAST SOUNDINGS AHEAD OF THE FRONT AT LITTLE ROCK AND
SHREVEPORT SHOW MLCAPE OF 500 TO 1000 J/KG WITH SFC DEWPOINTS IN THE
MID 60S TO NEAR 70 F. ALTHOUGH BOUNDARY LAYER WINDS ARE FORECAST TO
BE VEERED TO THE SOUTH-SOUTHWEST...STRONG DEEP-LAYER SHEAR IS
FORECAST ALONG WITH SOME DIRECTIONAL SHEAR IN THE LOW-LEVELS. THIS
SHOULD BE SUPPORTIVE OF SEVERE THUNDERSTORM DEVELOPMENT AS SEVERAL
LINE SEGMENTS ORGANIZE ALONG THE FRONT. IN ADDITION TO LINEAR
DEVELOPMENT...SUPERCELLS WILL BE POSSIBLE ASSOCIATED WITH LARGE HAIL
AND WIND DAMAGE AND A FEW TORNADOES.

..BROYLES.. 11/10/2015

 

Sounds like if supercells DO develop, a small moderate risk could eventually be introduced. 

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Sounds like if supercells DO develop, a small moderate risk could eventually be introduced. 

 

 

IF we do eventually see a moderate risk, I think it would be for tornadoes and probably in a concentrated area.  I'm not at all convinced there will be enough of a widespread wind damage threat to warrant a moderate risk.  I could easily see this staying as an enhanced risk all the way through though and I'd probably lean toward that outcome at this point.

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Agreed, I didn't think about timings, I screwed up. Direct any hate mail to my inbox.

Just sit back, read more and post less. Learn the etiquette and flow, and then feel free to add to the discussion. Flying off with posts of minimal information, and/or completely erroneous information rub many posters (including myself) the wrong way.

I am a winter guy, so I don't chat up too much in these severe setups, so I sit back and watch/learn. Do the same.

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IF we do eventually see a moderate risk, I think it would be for tornadoes and probably in a concentrated area. I'm not at all convinced there will be enough of a widespread wind damage threat to warrant a moderate risk. I could easily see this staying as an enhanced risk all the way through though and I'd probably lean toward that outcome at this point.

I would agree. I think someone (Alek maybe) eluded to it, but the action zone may be the radar hole in NE Mo and W Il. I may make a trip to Decatur to visit my parents, and head east on 72 towards Jacksonville/Quincy to do some chasing depending on how conditions play out.

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I would agree. I think someone (Alek maybe) eluded to it, but the action zone may be the radar hole in NE Mo and W Il. I may make a trip to Decatur to visit my parents, and head east on 72 towards Jacksonville/Quincy to do some chasing depending on how conditions play out.

 

 

I mean, I could be wrong and perhaps we end up with a solid line that has a lot of damaging wind reports, but the NAM/4 km NAM with its more discrete looking activity gives me pause and makes me wonder if it will be more in the way of discrete cells/broken lines.  Storm mode is definitely up in the air. 

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4 km NAM has been pretty adamant from the beginning about a primarily semi-discrete/discrete mode. Its 12 km counterpart and the Euro have generally been suggesting the same thing. I suppose this isn't surprising with such extreme deep layer shear present with vectors not parallel to the boundary.

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