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November 11th-12th storm system


Thundersnow12

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Always nice to have the storm still strengthening (quite quickly at that) during the event.  Shear vectors are pointing 90 degrees away from the arcing dryline surge.  Very strong vorticity advection.  Can definitely see why the high-res models are keeping things fairly discrete through early evening.  Pretty impressive given such strong forcing.  

With a storm speed of 60-70 MPH, the storms should outrun the front as well.

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Was looking forward to doing the forecast and AFD today for this event for LOT but unfortunately we're experiencing major technical difficulties in our system so MKX will be doing forecast for us today.

Sent from my SM-G900V

 

 

That sucks.

 

I think Gino pointed out something important in the overnight afd...this event has lower dewpoints for the LOT cwa than some of the CIPS analogs that produced severe weather.  Still can't rule it out obviously. 

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How high dewpoints get is a tough call. 12z guidance does get low-mid 50s dewpoints into the CWA by Wednesday evening. Looking at the 12z CIPS, the #2 analog, 11/10/98 and the #4 analog, 11/16/1988, produced severe wind reports within the CWA with dewpoints reaching the mid 50s.

Sent from my SM-G900V using Tapatalk

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How high dewpoints get is a tough call. 12z guidance does get low-mid 50s dewpoints into the CWA by Wednesday evening. Looking at the 12z CIPS, the #2 analog, 11/10/98 and the #4 analog, 11/16/1988, produced severe wind reports within the CWA with dewpoints reaching the mid 50s.

Sent from my SM-G900V

 

 

I was looking at the 11/16/1988 analog more closely earlier, and it looks like the severe reports in LOT mainly came late in the evening on the 15th or perhaps just after midnight on the 16th.  Looking at hourly obs from RFD and ORD, dews were actually a bit higher at that time...around 60.

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I was looking at the 11/16/1988 analog more closely earlier, and it looks like the severe reports in LOT mainly came late in the evening on the 15th or perhaps just after midnight on the 16th. Looking at hourly obs from RFD and ORD, dews were actually a bit higher at that time...around 60.

Ah okay, I was only looking at thumbnails on the CIPS page. If we had an extra day of moisture return ahead of this system, would be much more concerned for a fairly widespread outbreak, though mid 50s may be enough to at least get some severe into the CWA given everything else going for this.
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Ah okay, I was only looking at thumbnails on the CIPS page. If we had an extra day of moisture return ahead of this system, would be much more concerned for a fairly widespread outbreak, though mid 50s may be enough to at least get some severe into the CWA given everything else going for this.

 

 

fwiw, from what I can tell, the wind fields are better this time than November 1988, especially aloft.

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Although it's not likely, the line could sustain through southern MI if the NAM verifies.

 

also FWIW 12 GFS/NAM/ECMWF is more windy.

 

First High Wind Watch up for the System:

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE DODGE CITY KS
1216 PM CST MON NOV 9 2015

...POWERFUL LOW PRESSURE SYSTEM WILL TRACK ACROSS CENTRAL PLAINS
ON VETERANS DAY...

.A VERY INTENSE LOW PRESSURE SYSTEM WILL MATURE ACROSS WESTERN
KANSAS WEDNESDAY MORNING. AS THE LOW BEGINS TO MOVE INTO NORTHERN
KANSAS BY MIDDAY, HIGH WINDS WILL DEVELOP IN ITS WAKE. HIGH WINDS
ARE LIKELY FROM LATE MORNING THROUGH THE AFTERNOON HOURS
WEDNESDAY.

KSZ030-031-043>046-061>066-074>081-084>090-100600-
/O.NEW.KDDC.HW.A.0001.151111T1400Z-151111T2200Z/
TREGO-ELLIS-SCOTT-LANE-NESS-RUSH-HAMILTON-KEARNY-FINNEY-HODGEMAN-
PAWNEE-STAFFORD-STANTON-GRANT-HASKELL-GRAY-FORD-EDWARDS-KIOWA-
PRATT-MORTON-STEVENS-SEWARD-MEADE-CLARK-COMANCHE-BARBER-
INCLUDING THE CITIES OF...WAKEENEY...CEDAR BLUFF RESERVOIR...
HAYS...ELLIS...SCOTT CITY...DIGHTON...NESS CITY...LA CROSSE...
RUSH CENTER...SYRACUSE...LAKIN...DEERFIELD...GARDEN CITY...
KALVESTA...JETMORE...HANSTON...LARNED...BURDETT...ST. JOHN...
STAFFORD...HUDSON...JOHNSON CITY...ULYSSES...SUBLETTE...SATANTA...
CIMARRON...MONTEZUMA...DODGE CITY...BUCKLIN...KINSLEY...LEWIS...
GREENSBURG...HAVILAND...PRATT...ELKHART...RICHFIELD...HUGOTON...
MOSCOW...LIBERAL...KISMET...MEADE...FOWLER...ASHLAND...MINNEOLA...
COLDWATER...PROTECTION...MEDICINE LODGE...KIOWA...SUN CITY
1216 PM CST MON NOV 9 2015 /1116 AM MST MON NOV 9 2015/

...HIGH WIND WATCH IN EFFECT FROM WEDNESDAY MORNING THROUGH
WEDNESDAY AFTERNOON...

THE NATIONAL WEATHER SERVICE IN DODGE CITY HAS ISSUED A HIGH WIND
WATCH...WHICH IS IN EFFECT FROM WEDNESDAY MORNING THROUGH
WEDNESDAY AFTERNOON.

* TIMING...LATE MORNING THROUGH AFTERNOON WEDNESDAY.

* WINDS...NORTHWEST AT 35 TO 45 MPH WITH GUSTS TO 60 MPH.

* IMPACTS...INTENSE CROSSWINDS ON OPEN HIGHWAYS WILL MAKE TRAVEL
DIFFICULT, ESPECIALLY AROUND GRAIN ELEVATORS. LIGHT STRUCTURAL
DAMAGE IS POSSIBLE, ESPECIALLY TO ROOFS. SOME COMMERCIAL POWER
INTERRUPTION IS ALSO POSSIBLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HIGH WIND WATCH MEANS THERE IS THE POTENTIAL FOR A HAZARDOUS
HIGH WIND EVENT. CONTINUE TO MONITOR THE LATEST FORECASTS.

&&

$

UMSCHEID

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I just looked at ILN's criteria for high wind watch/warnings and wind advisories... looks like we're gonna have a high-end wind advisory. If the criteria is the same for North Illinois, they might barely meet the criteria for high wind watch (gusts >58 MPH)... but certainly, the lower GL should light up with wind advisories.

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I almost wonder if 700-500 mb lapse rates may not be as crucial in this setup...I'm not saying to ignore and that they don't matter, but a lot of the forecast soundings I've been looking at don't even have the EL reaching up to 500 mb, especially as you move farther east.  I think something like 850-700 mb lapse rates may be better.

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I almost wonder if 700-500 mb lapse rates may not be as crucial in this setup...I'm not saying to ignore and that they don't matter, but a lot of the forecast soundings I've been looking at don't even have the EL reaching up to 500 mb, especially as you move farther east.  I think something like 850-700 mb lapse rates may be better.

 

I have to agree with you here. If this is going to be a low topped supercell threat then perhaps we should be focusing more on the 0-3km CAPE values anyway. And some of them from yesterday looked pretty potent. I haven't looked at any today and I don't have access to my normal tools. Perhaps some of you guys can post a SHARPpy sounding or two or at least report on what the low level CAPE is looking like?

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ILX has another good AFD

 

SPC has most of the CWA in a slight risk of severe weather for Wed
along with an enhanced risk area in southwest parts of the CWA. With
Bulk Shear at 0-6km over 80kts and 0-3km SRH over 400 m/s, believe
storms/strong showers that develop will likely rotate. With dwpts
only getting into the 50s in IL, instability may be limited, but
models continue to show near 500 CAPE in southeast IA, west IL, and
northeast MO. This is also where some of the best wind turning will
be as it is closes area to the sfc low moving across IA. With higher
moisture being southwest of the area, agree with SPC that enhanced
area should be where best instability should be. Besides the limited
moisture, another negative with this event will be the storms should
be moving around 50 mph...which combined with the strong shear, the
updrafts could have trouble holding together. Looking at everything,
still believe strong to severe weather is likely in our CWA
beginning last Wed afternoon through Wed evening. Mid and upper
level lapse rates do not look high enough to support hail with this
event, so thinking is that main severe weather concern will be
damaging winds. With ML LCLs forecasted to be below 500m and the
environment being High Shear/Low CAPE, think a few tornadoes will
also be possible. Will definitely take a closer look at the models
the next several runs.

 

 

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Since there's a good shot that this thing kicks off early, the best tor threat may be fairly early on way out west over southeast NE/southwest IA near cold core center.  NAM has consistently forecast cape at it's highest earlier in the day as well.  If I were chasing I'd probably plan on heading out to southwestern IA and hope I didn't have to head even further west into NE, which is possible.

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LMK has an interesting take

 

Wednesday will be dry as surface high pressure and progressive upper
ridge axis hold over our region. A steady south wind and mostly
sunny to partly cloudy skies will allow temps to rise into the upper
60s and low 70s in some spots during the afternoon.

Upstream, a potent upper system (characterized by 150 kt upper level
jet, and 100-110 kt 500 mb jet) will eject out of the southern
Plains and into the mid Mississippi River Valley by Wednesday
evening. 500 mb trough will take on a negative tilt during this
transition. Associated surface low will deepen as it moves from
western KS to western IA. Strong upper divergence will overspread
the mid Mississippi and Ohio River Valleys through the afternoon and
into the evening hours, resulting in a strong low level jet (50-60
kts) response. At the surface, SSE winds will increase in response
to the pressure falls. Expecting to see 15 to 20 mph, occasionally
gusting around 25-30 mph Wednesday evening into Wednesday night.

Wind fields are undoubtedly impressive, however question continues
to remain with regard to instability. Surface based instability axis
continues to look meager to non-existent as only a very narrow
corridor of 55-60 dew points will build ahead of the cold front.
Despite the lack of instability, still think pockets of gusty to
potentially damaging winds will be possible within strongly forced
line via a couple of bowing segments, particularly across our
western CWA. Organized line of storms should overall weaken as they
progress east through the overnight.


Also, am a bit concerned about a secondary line of showers/storms
right along the frontal boundary, which seems to coincide with the
best
instability axis. Low level theta surfaces become vertical
during this time which could allow 30 to 40 mph
gradient wind gusts.
Gust potential could then be enhanced by any shower/storm. It is
entirely possible that this could be the worst part of the event,
with the pre-frontal
trough acitivity too elevated for wind damage
and mainly just gusty
stratiform rain. Either way, the main threat
Wednesday evening will be gusty winds, with a few pockets of
damaging winds likely. Rainfall totals really don`t look all that
impressive given the speed that the system moves through. A brief
spin-up tornado threat is non-zero, but at this point seems pretty
unlikely given the unimpressive dew points and the lack of at least
a little bit of surface based instability.

 

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If the general model solutions hold, I'd bet on a northward expansion of the enhanced risk area especially in IA/IL. Actually I think you could make a case that the northern area looks as good if not better than farther south.

This. I'd bring the slight as far north as S. WI/SW. MI and shift the enhanced north from SGF-PAH up to I-80.
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If the general model solutions hold, I'd bet on a northward expansion of the enhanced risk area especially in IA/IL.  Actually I think you could make a case that the northern area looks as good if not better than farther south.

 

It's becoming kind of obvious that Broyles doesn't really look at a lot of things before issuing his outlooks (or at least it really comes across that way). That 06z D1 outlook for 4/9 is another case, where parts of it literally made zero sense.

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It's becoming kind of obvious that Broyles doesn't really look at a lot of things before issuing his outlooks (or at least it really comes across that way). That 06z D1 outlook for 4/9 is another case, where parts of it literally made zero sense.

 

For those who need a refresher on that

-Note that the wind report in Hillsdale and few other places are later verified tornadoes: day1otlk_v_20150409_1200.gif

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It's becoming kind of obvious that Broyles doesn't really look at a lot of things before issuing his outlooks (or at least it really comes across that way). That 06z D1 outlook for 4/9 is another case, where parts of it literally made zero sense.

 

 

I'm speculating here but I think it's possible there's some thought to be conservative with northern target areas in November, given that instability is often lackluster.  I think there's enough consistency at this point to expand it north on the day 2 outlook later.

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