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June 7-8 Severe Weather Threat


snowlover2

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Gino is thinking morning complex stays north, backed off to a 30% probability of thunderstorms at the airports in his terminal forecasts this evening.

 

 

Are you leaning any particular way right now?  Personally, I wouldn't be surprised to see some remnant convection make it into the area during the morning (which has at least some model support), but I don't think it's going to be enough to be a deal breaker for later in the day as I anticipate enough recovery behind whatever boundary may come through.  Thinking initiation/refiring right in the metro area tomorrow.

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Are you leaning any particular way right now?  Personally, I wouldn't be surprised to see some remnant convection make it into the area during the morning (which has at least some model support), but I don't think it's going to be enough to be a deal breaker for later in the day as I anticipate enough recovery behind whatever boundary may come through.  Thinking initiation/refiring right in the metro area tomorrow.

 

Yeah that's what I'm thinking as well.  The models show the LLJ ramping up quite a bit later tonight which should maintain it through tomorrow morning.  Most of the models move it out by mid-morning, which should leave plenty of time to recover.  

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What will most likely happen (which typically does in these setups) is that the MCS will split into 2 parts. The strong/severe storms will dive SE into western IL/MO along the instability gradient, while the stratiform rains continue to track ENE with the shortwave into WI/MI. In between, they'll probably be a ton of cirrus debris and an outflow bubble.

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Interesting to see what the 18z 4km is doing...storm blows up in northern IL and moves SE (with mostly veered flow on the synoptic scale) but if you look closely at the sfc winds, it seems to modify the near storm environment to it's southeast and locally backs the sfc winds which would really increase your 0-1km SRH values..

 

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At first glance, 0z NAM might have a slower/further north front location. 500mb eight field at 12/15z is def further north compared to 18z run.

It is further north with the overnight MCS as well which it better represents the current radar.
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SPC update last hour expanded the slight risk tonight into eastern Iowa.  There should be a line of storms reaching Cedar Rapids around 4am.  Previous complexes this spring have died overnight, but a nice low level jet veering into eastern Iowa is forecast to keep the storms going longer this time.  Strong wind gusts should be the main risk.

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Are you leaning any particular way right now? Personally, I wouldn't be surprised to see some remnant convection make it into the area during the morning (which has at least some model support), but I don't think it's going to be enough to be a deal breaker for later in the day as I anticipate enough recovery behind whatever boundary may come through. Thinking initiation/refiring right in the metro area tomorrow.

I'm pretty much leaning that way as well. I like that the 4km NAM has been pretty consistent in that general scenario for several runs in a row. Things could go linear pretty quick but assuming the idea of refiring over the metro pans out, the better chance for discrete/semi-discrete could be within 1-2 hrs of initiation.

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New day 1

 

 

 

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1259 AM CDT SUN JUN 07 2015  
 
VALID 071200Z - 081200Z  

 
...THERE IS AN ENH RISK OF SVR TSTMS TODAY INTO THIS EVENING ACROSS  
PARTS OF NORTHERN AND CENTRAL ILLINOIS...NORTHERN AND CENTRAL  
INDIANA...AND EXTREME SOUTHWEST LOWER MICHIGAN...  
 
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ENH RISK AREA  
ACROSS THE SOUTHERN GREAT LAKES AND OH VALLEY THROUGH THE LOWER MO  
VALLEY TO PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS...  
 
...THERE IS A MRGL RISK OF SVR TSTMS EXTENDING FROM THE GREAT LAKES  
AND OH VALLEY TO THE CENTRAL AND SOUTHERN HIGH PLAINS...  
   
..SUMMARY
 
 
SEVERE THUNDERSTORMS WILL BE POSSIBLE TODAY FROM PARTS OF THE LOWER  
GREAT LAKES AND OHIO VALLEY REGION TO THE CENTRAL AND SOUTHERN HIGH  
PLAINS...WITH THE GREATEST POTENTIAL ACROSS NORTHERN AND CENTRAL  
PORTIONS OF ILLINOIS AND INDIANA...AND FAR SOUTHWEST LOWER MICHIGAN.  
   
..SYNOPSIS
 
 
A MIDLEVEL SPEED MAX WILL CROSS PORTIONS OF THE MIDDLE/UPPER MS  
VALLEY AND GREAT LAKES REGION ON THE SOUTH SIDE OF A  
BROAD/AMPLIFYING TROUGH ACROSS THE UPPER/MIDDLE MS VALLEY AND GREAT  
LAKES REGION. A RELATED SURFACE LOW WILL ADVANCE ACROSS PARTS OF  
NRN WI AND UPPER MI INTO ADJACENT ONTARIO...REACHING SWRN QUEBEC BY  
12Z MONDAY. A COLD FRONT EXTENDING SW OF THE SURFACE LOW TO THE CO  
ROCKIES FRONT RANGE WILL ADVANCE EAST AND SOUTH TOWARD LOWER  
MI...INTO THE MIDWEST...LOWER MO VALLEY AND THROUGH THE CENTRAL  
PLAINS. THE LEADING EDGE OF THE WARM SECTOR WILL ADVANCE NNEWD  
ACROSS SRN AND ERN PORTIONS OF THE GREAT LAKES REGION...ESTABLISHING  
A BROAD CORRIDOR OF RICH GULF RETURN MOISTURE AHEAD OF THE COLD  
FRONT. MEANWHILE...A MIDLEVEL TROUGH WILL ELONGATE ENE/WSW OVER  
PARTS OF THE GREAT BASIN TO CENTRAL ROCKIES...BETWEEN FLANKING  
RIDGES OVER THE SRN PLAINS AND NWRN STATES.  
   
..SRN GREAT LAKES/OH AND MID MS VALLEYS
 
 
AN ONGOING MCS...POSSIBLY PRODUCING STRONG TO SEVERE STORMS...SHOULD  
BE MOVING THROUGH ERN WI...FAR NRN IL AND WEST-CENTRAL IL PER RECENT  
HRRR RUNS/00Z NAM/12Z ECMWF. MODERATE-STRONG INSTABILITY IS  
EXPECTED ACROSS THE WARM SECTOR...GIVEN LOW-LEVEL MOISTENING  
/SURFACE DEW POINTS IN THE MID-UPPER 60S/ AS FAR EAST AS SRN LOWER  
MI AND WRN OH AND DIABATIC HEATING. THE LEADING EXTENT OF THE EARLY  
MORNING MCS SHOULD RE-INTENSIFY IT REACHES SWRN LOWER MI AND NRN IL  
/INCLUDING THE CHICAGO METRO AREA/ BY EARLY AFTERNOON. EFFECTIVE  
BULK SHEAR OF 30-35 KT ORIENTED GENERALLY PARALLEL TO THE CONVECTIVE  
OUTFLOW BOUNDARY SUGGESTS LINE SEGMENTS/BOWING STRUCTURES AS THE  
PRIMARY STORM MODE WITH DAMAGING WINDS THE PRIMARY THREAT.  
HOWEVER...ENHANCED LOW-LEVEL SHEAR ALONG MODESTLY STRONG SWLY  
LOW-LEVEL WINDS WILL FAVOR A TORNADO THREAT.  
 
THE POTENTIAL EXISTS FOR AFTERNOON STORMS TO CONGEAL INTO A  
WSW/ENE-ELONGATED QUASI-LINEAR MCS THROUGH THE EARLY EVENING HOURS.  
THIS ACTIVITY SHOULD BE LARGELY ORIENTED PARALLEL TO THE MEAN  
CLOUD-LAYER FLOW...WHILE GRADUALLY SPREADING ESEWD/SEWD INTO PARTS  
OF CENTRAL IL...CENTRAL INDIANA...NWRN OH...SERN IL AND PARTS OF WRN  
OH. DAMAGING WINDS AND MARGINALLY SEVERE HAIL WILL REMAIN POSSIBLE  
WITH THIS ACTIVITY AS CONVECTION REGENERATES/SPREADS INTO A  
MOIST/MODERATELY UNSTABLE AIR MASS.  
   
..PORTIONS OF NRN/CENTRAL MO WWD TO ERN CO
 
 
ASCENT SUPPORTING CONVECTION WILL BE PRIMARILY CONFINED TO LOW-LEVEL  
CONVERGENCE PROCESSES RELATED TO THE COLD FRONT AND THE TRAILING  
EXTENT OF THE OUTFLOW BOUNDARY ATTENDANT TO THE WI/NRN IL MCS AS IT  
SETTLES SWD. ISOLATED TO WIDELY SCATTERED TSTMS WILL LIKELY DEVELOP  
NEAR THESE BOUNDARIES AND WWD TO DIURNALLY ENHANCED OROGRAPHIC  
CIRCULATIONS OVER THE CO FRONT RANGE AND MOIST/UPSLOPE FLOW TO ITS  
E. THE PRESENCE OF 25-35 KT OF DEEP SHEAR WILL HAVE THE POTENTIAL TO  
SUPPORT ORGANIZED/SUSTAINED CONVECTIVE STRUCTURES/POSSIBLE  
SUPERCELLS. IN THE ABSENCE OF A STRONG EQUATORWARD SURGE OF LOW  
THETA-E AIR...CONVECTION SHOULD ALSO EVOLVE BEHIND THE COLD FRONT IN  
PARTS OF E-CNTRL CO INTO NRN KS AND PERHAPS FAR SRN NEB WHERE  
POST-FRONTAL DIRECTIONAL-FLOW VARIABILITY IN THE LOW-LEVELS WILL  
BOLSTER DEEP SHEAR /POTENTIAL FOR ORGANIZED STORMS/. A  
STRENGTHENING SWLY LLJ FROM OK INTO SERN KS AND MO MAY AID IN  
SUSTAINING TSTMS THROUGH THE EVENING INTO THE EARLY OVERNIGHT PERIOD  
ACROSS SERN KS TO CENTRAL MO WITH A LINGERING THREAT FOR STRONG TO  
SEVERE STORMS.  
 
..PETERS/DEAN.. 06/07/2015  

 

post-4544-0-70712000-1433657261_thumb.pn

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gonna be a dying complex followed by a re-fire just south tomorrow.

 

nailed part 1

 

Gino is thinking morning complex stays north, backed off to a 30% probability of thunderstorms at the airports in his terminal forecasts this evening.

 

:yikes:

 

these overnight MCS love to dive south into the better instability, no way this thing would hang north

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nailed part 1

:yikes:

these overnight MCS love to dive south into the better instability, no way this thing would hang north

Good call. 850-300 mb winds were basically straight out of the west so based on where it formed, it had no choice but to go east.

Biggest thing in favor of recovery and refiring now is how early this MCS is pushing through.

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nailed part 1

 

 

:yikes:

 

these overnight MCS love to dive south into the better instability, no way this thing would hang north

 

Yeah, RPM forecasts and other short term models failed with how far south this morning crapvection extended, and I could tell it would last night when the strongest storms were in E Nebraska heading E and ESE.

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HRRR recovers most of IL/IN/MI fairly nicely. A nice "cellular" squall line develops later this afternoon. 

 

IT's also assuming widespread highs in the mid/upper 80s and 

 

With the cloud cover expected this afternoon, I'm thinking the HRRR is a little too ambitious. 

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FAirly notable changes on the latest SPC outlook...

 

day1otlk_1300.gif?1433682355596

 

...IL/INDIANA/SRN LOWER MI/WRN OH THIS AFTERNOON/EVENING...
A WELL-DEVELOPED MCV OVER SW WI AND ASSOCIATED MCS WILL CONTINUE EWD
ACROSS SRN WI/NRN IL THIS MORNING...AND WILL REACH SW LOWER MI AND
NW INDIANA BY MID MORNING AS THE CONVECTION WEAKENS. OUTFLOW WITH
THIS MORNING CONVECTION WILL PRECEDE THE SYNOPTIC COLD FRONT
ACCOMPANYING A MIDLEVEL SHORTWAVE TROUGH THAT WILL MOVE ESEWD FROM
THE DAKOTAS/MN THIS MORNING TO THE UPPER GREAT LAKES OVERNIGHT.
ADDITIONAL THUNDERSTORM DEVELOPMENT IS EXPECTED ALONG THE OUTFLOW BY
EARLY-MID AFTERNOON FROM SRN IA/NRN MO ACROSS NRN/CENTRAL IL INTO
NRN INDIANA.

LOW-LEVEL MOISTENING TO THE S OF THE OUTFLOW AND SOME INCREASE IN
LOW-LEVEL SHEAR THIS AFTERNOON WILL PROVIDE A FAVORABLE ENVIRONMENT
FOR MULTICELL CLUSTERS TO GROW INTO LINE SEGMENTS THIS
AFTERNOON...GIVEN RELATIVELY WEAK DEEP-LAYER VERTICAL SHEAR WITH
FLOW LARGELY PARALLEL TO THE BOUNDARY. ISOLATED LARGE HAIL WILL BE
POSSIBLE...THOUGH MODEST MIDLEVEL LAPSE RATES AND RELATIVELY WEAK
DEEP-LAYER SHEAR WILL TEMPER THE HAIL RISK TO SOME EXTENT. ANY
TORNADO RISK WILL LIKELY DEPEND ON STORM-SCALE INTERACTIONS SINCE
DEEP-LAYER SHEAR AND EXPECTED CONVECTIVE MODE DO NOT FAVOR
SUPERCELLS. THUS...DAMAGING WINDS WILL BE THE MAIN CONCERN.

..THOMPSON/COOK.. 06/07/2015

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