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June 21-27 Severe Weather


Chicago Storm

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New day 2 likes IN/OH.

 

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1210 AM CDT TUE JUN 25 2013  
 
VALID 261200Z - 271200Z  
 
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MIDWEST TO THE OH  
VALLEY...  
   
..MIDWEST/OH VALLEY/SRN GREAT LAKES  
 
WEAK HEIGHT FALLS ARE EXPECTED TO SPREAD SEWD ACROSS THE UPPER MS  
VALLEY INTO THE GREAT LAKES/OH VALLEY WEDNESDAY AS PROGRESSIVE  
SHORT-WAVE TROUGH TOPS THE CNTRL U.S. RIDGE AND DIGS SEWD. BY 18Z  
THIS FEATURE IS EXPECTED TO EXTEND FROM CNTRL WI SWD ACROSS  
IL...WITH SUBSEQUENT MOVEMENT INTO OH BY 27/12Z. IN RESPONSE TO  
THIS FEATURE VEERED LLJ SHOULD TRANSLATE ACROSS MO INTO IND BY  
AFTERNOON. NET RESULT IS DEEP LAYER SHEAR IS FORECAST TO INCREASE  
ACROSS IL/IND AS 500MB FLOW INCREASES TO 40-45KT...MORE THAN  
ADEQUATE FOR DEVELOPMENT/MAINTENANCE OF DISCRETE SUPERCELL  
STRUCTURES.  
 
EARLY IN THE PERIOD A CONSIDERABLE AMOUNT OF CONVECTION MAY BE  
ONGOING WITHIN WARM ADVECTION ZONE ACROSS SERN MN/NERN IA...EWD  
ALONG THE WI/IL BORDER INTO SRN MI. THIS ACTIVITY MAY BE AN  
EXTENSION OF LATE DAY1 CONVECTION ALONG WITH NEW DEVELOPMENT DUE TO  
FOCUSED UVV ACROSS THIS REGION. LARGE HAIL/DAMAGING WINDS COULD BE  
NOTED WITH THIS ACTIVITY BUT EARLY MORNING INSTABILITY MAY BE  
REDUCED SOMEWHAT AS CLOUDS/PRECIPITATION SHOULD LIMIT SUNSHINE OVER  
WI/MI. HOWEVER...STRONG HEATING IS EXPECTED ACROSS THE MID MS  
VALLEY WITHIN STRONGLY VEERED DEEP LAYER FLOW. BY MID AFTERNOON SFC  
TEMPERATURES SHOULD WARM SUFFICIENTLY FOR SFC-BASED CONVECTION AND  
SCT TSTMS ARE EXPECTED TO DEVELOP AHEAD OF NE-SW ORIENTED CONFLUENCE  
ZONE OVER IL. EXTREME INSTABILITY...SBCAPE ON THE ORDER OF  
4000-5000 J/KG...WITH SFC-6KM BULK SHEAR OF 35-40KT SHOULD ENHANCE  
THE LIKELIHOOD FOR SUPERCELLS. VERY LARGE HAIL AND DAMAGING WINDS  
CAN BE EXPECTED WITH THIS ACTIVITY. DESPITE THE STRONGLY VEERED  
FLOW REGIME DEW POINTS ARE EXPECTED TO HOLD IN THE LOWER 70S AND A  
FEW TORNADOES MAY ALSO BE NOTED.  
 
A FEW SUPERCELLS AND MULTIPLE THUNDERSTORM CLUSTERS SHOULD ADVANCE  
ACROSS THE OH VALLEY DURING THE LATTER HALF OF THE PERIOD IN  
ASSOCIATION WITH AFOREMENTIONED SHORT-WAVE TROUGH. ACTIVITY COULD  
EASILY ADVANCE INTO WRN PA BY SUNRISE THURSDAY AS LLJ SHIFTS INTO  
THIS REGION.  
 
..DARROW.. 06/25/2013

 

 

post-4544-0-90439800-1372137791_thumb.gi

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Wednesday is beginning to look like a moderate risk, given the expectation of convective initiation, excessive instability and adequate shear. If we can get some more directional shear throughout the profile (there already is a decent amount), then tornado possibilities will accordingly rise. Definitely a solid NW flow setup looking to be developing here.

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Nice line starting to form in southern WI. Cells firing off further east towards the southwest MKE metro.

cells poppin' off south of the lake (prolly just champagne droplets seeding the clouds downwind) and random little buggers poppin' west of 39....looks like a soaker of a night for the WI/IL border on tap

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Wednesday is beginning to look like a moderate risk, given the expectation of convective initiation, excessive instability and adequate shear. If we can get some more directional shear throughout the profile (there already is a decent amount), then tornado possibilities will accordingly rise. Definitely a solid NW flow setup looking to be developing here.

Moderate Risk?  Which area do you think?  Illinois?

 

To answer my own question here... the SREF shows 4000 CAPE and 35 knots of shear near St. Louis and western Illinois. You would tend to think that a 30% or 45%(moderate) would be in that area, if that level of outlook exists.

 

edit(again.) Dang. should have read 05z SPC outlook (Day 2) (for Wednesday) an hour ago, before posting this question. 

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update from LOT...

 

.

NEXT BEST CHANCE FOR CONVECTION APPEARS TO BE MID TO LATE IN THE
AFTERNOON TUESDAY INTO THE EARLY EVENING. MODERATE TO STRONG AND
WEAKLY CAPPED INSTABILITY IS ONCE AGAIN EXPECTED TO DEVELOP EARLY IN
THE AFTERNOON...BUT THE BEST CHANCE FOR MORE WIDESPREAD CONVECTION
WILL BE LATE IN THE AFTERNOON AS A MID LEVEL DISTURBANCE CURRENTLY
OVER CENTRAL KANSAS MOVES OVER THE AREA. CONDITIONS APPEAR FAVORABLE
FOR ANOTHER FORWARD PROPAGATING COMPLEX SIMILAR TO MONDAY AFTERNOON
STORMS TO MOVE ACROSS THE REGION.

.

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cells poppin' off south of the lake (prolly just champagne droplets seeding the clouds downwind) and random little buggers poppin' west of 39....looks like a soaker of a night for the WI/IL border on tap

 

If it's anything like Saturday night, it's going to be a hard rain later on. Milwaukee into Lake County look to be in line for this. 1.5"-2" per hour rainfall rates coming out of Grant, Lafayette, and Iowa Counties.

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Indiana looking very interesting for Wed.  Strong mid levels blasting in from the northwest overtop a nice southerly flow at the surface, along with plenty of instability.  As long as morning leftovers don't mess the setup up too much it could be a big day for far eastern IL and almost all of IN.

 

Yeah, given that the prevailing flow/storm motion should be more easterly today as opposed to southeasterly, that should allow at least some areas to remain relatively untouched for Wednesday.

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Indiana looking very interesting for Wed.  Strong mid levels blasting in from the northwest overtop a nice southerly flow at the surface, along with plenty of instability.  As long as morning leftovers don't mess the setup up too much it could be a big day for far eastern IL and almost all of IN.

Wednesday afternoon, the GFS has 79 dew points south of St. Louis.

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The GFS had dew points too high for a lot of situations last summer, but they fixed the computer code last summer (or something like that). I still wouldn't be surprised if the GFS predicted 5500 J/kg CAPE verifies in SE Missouri that day.

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DTX on Wed

 

VERY ACTIVE SUMMER WEATHER WILL CONTINUE ON WEDNESDAY. MIDLEVEL
TROUGH OVER THE GREAT BASIN AT 25.00Z WILL CUT THROUGH/SHEAR OFF THE
RIDGE STRUCTURE IN THE CENTER OF THE CONTINENT. THE TROUGH AND
COLLECTION OF VORTICITY ENERGY BLOCKED UP BEHIND IT WILL SLIDE
THROUGH SOUTHEASTERN MICHIGAN DURING THE DAYTIME HOURS ON WEDNESDAY.
A LOW TO MIDLEVEL LOW PRESSURE SYSTEM IS SHOWN TO BE AMPLIFYING
IMMEDIATELY UPSTREAM AS IT ARRIVES. THERE IS HIGH CONFIDENCE WITH
THIS FEATURE GIVEN VERY GOOD CONVERGENCE/WAA/JET STREAM CONTINUITY.
VIRTUALLY IMPOSSIBLE TO KNOW EXACTLY WHAT WILL BE GOING ON AT THE
START OF THE PERIOD...BUT ANOTHER EASY CALL FOR HIGH CHANCE POPS
SOME 30 TO 40 HOURS OUT. THE SOUNDING IS CAPPED FOR SFC BASED
CONVECTION DURING THE MORNING...TRANSITIONING TO WEAKLY CAPPED BY
THE AFTERNOON. PATTERN PERSISTENCE AND NOTABLY STEEP MIDLEVEL LAPSE
RATES SUGGESTS THAT MLCAPES WILL BE NORTH OF 1500 J/KG...EITHER OVER
THE SOUTHERN CWA OR AVAILABLE FOR INGEST IMMEDIATE SOUTH. 0-6KM BULK
SHEAR PROGS ARE NOW ADVERTISING OVER 40 KNOTS DURING THE DAYTIME
COURTESY OF ANOTHER DYING LOW LEVEL JETLET. WHAT MAY BE THE MOST
IMPORTANT OF ALL IS THAT MODELS ARE COMING INTO AGREEMENT WITH A
SECONDARY WARM FRONT FEATURE LIFTING INTO SOUTHEASTERN MICHIGAN
DURING THE LATE MORNING/EARLY AFTERNOON ALONG WITH A SPIKE IN SRH
VALUES IMMEDIATELY IN ADVANCE OF IT. NWP IS DEPICTING STRONGLY
BACKED FLOW OVER SOUTHEASTERN MICHIGAN AS WELL AS A TRIPLE POINT
RELEASING OFF OF LAKE MICHIGAN BETWEEN THE PEAK DIURNAL PERIOD
18-21Z. THESE ARE SIGNS THAT AN ELEVATED POTENTIAL FOR
TORNADOGENESIS MAY EXIST. THE LIMITING FACTOR IN CONFIDENCE THOUGH
IS PLACEMENT/COVERAGE OF THUNDERSTORMS EARLY IN THE DAY AND WHAT
SORT OF EFFICIENCY THERE WILL BE TO TURN THE AIRMASS OVER. A SLIGHT
RISK FOR SEVERE WEATHER WILL EXIST FOR ALL OF THE CWA...ALTHOUGH THE
SOUTHERN ONE THIRD APPEARS TO BE IN LINE FOR THE MORE SIGNIFICANT
SEVERE THREAT.

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MESOSCALE DISCUSSION 1217

NWS STORM PREDICTION CENTER NORMAN OK

0752 AM CDT TUE JUN 25 2013

AREAS AFFECTED...NRN IL INTO NWRN IND AND SWRN LOWER MI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 251252Z - 251345Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...A SVR TSTM WATCH MAY BE NEEDED FOR PART OF NRN IL INTO

NWRN IND /INCLUDING THE CHICAGO METRO AREA/...AND POSSIBLY SWRN

LOWER MI. A LINE OF TSTMS WILL MOVE E/ESEWD THIS MORNING...POSING A

THREAT FOR DAMAGING WINDS --- ESPECIALLY WITH EWD EXTENT AS THE

BOUNDARY LAYER DESTABILIZES.

DISCUSSION...A CLUSTER OF TSTMS THAT WAS LOCATED IN CENTRAL TO NERN

IA HAVE GROWN UPSCALE INTO A FORWARD PROPAGATING MCS ACROSS THE

UPPER MS VALLEY EARLY THIS MORNING. AT 1220Z...MOSAIC RADAR IMAGERY

SHOWED A LINE OF STORMS WITH THIS MCS EXTENDING FROM EXTREME SOUTH

CENTRAL WI /GREEN COUNTY/ TO ALONG THE NWRN IL/IA BORDER /CARROLL

COUNTY IL TO CLINTON COUNTY IA/. ADDITIONAL STORMS WERE DEVELOPING

FARTHER TO THE SOUTH...JUST TO THE EAST OF KMLI. THIS LINE OF

STORMS WAS MOVING ESEWD CLOSE TO 45 KT...AND THUS FAR HAS REMAINED

LOCATED NORTH OF AN E-W ORIENTED OUTFLOW BOUNDARY FROM AN EARLIER

CONVECTIVE SYSTEM. DESPITE THE CURRENT LOCATION OF THE CONVECTIVE

LINE...WHICH HAS SHOWN SOME TENDENCY TO BOW...VISIBLE SATELLITE

IMAGERY INDICATED POTENTIAL FOR SURFACE HEATING OVER NRN IL AND

TEMPERATURES ARE ALREADY RISING PER TRENDS IN SURFACE OBSERVATIONS.

ADDITIONAL SURFACE HEATING WILL AID IN THE DEVELOPMENT FOR STRONGER

INSTABILITY AND THE POTENTIAL FOR STRONGER WIND GUSTS TO REACH THE

SURFACE...GIVEN DEWPOINTS ALONG AND SOUTH OF THE E-W BOUNDARY OF

AROUND 70 DEGREES. THIS BOUNDARY EXTENDED FROM FAR NWRN OH WWD

THROUGH NRN IND /15 N KFWA TO 30 SW KVPZ/ INTO NRN IL /15 ENE KMMO

TO 25 NE KMLI/.

THE DESTABILIZATION COMBINED WITH A 40-50 KT WLY MIDLEVEL JET

EXTENDING FROM ERN IA TO SRN LOWER MI SUGGESTS STORMS COULD PERSIST

EWD...AT LEAST TO SRN LAKE MICHIGAN AND POSSIBLY INTO FAR NWRN IND

AND SWRN LOWER MI. HOWEVER...A WEAKENING TREND OF A WLY LLJ COULD

PROVE A LIMITING FACTOR IN THE EWD SPEED OF THIS LINE OF STORMS.

THUS...WW ISSUANCE IS POSSIBLE THIS MORNING IF A BOWING STRUCTURE

BECOMES BETTER ORGANIZED.

..PETERS/HART.. 06/25/2013

ATTN...WFO...IWX...GRR...LOT...DVN...

LAT...LON 41779014 42108982 42478964 42438796 42378723 42198542

41578551 41108591 41298766 41508897 41779014 

 

New MD out for the current MCS.

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Bright sunshine now. Man it's like a swamp out there. Feels like things could really explode if heating continues.

yeah...sun has been out here for a good 30 minutes now....even if things don't blow up this morning there should be a few extra boundaries left hanging around...

 

CAPE's nosing up, but with some CAP lingering around still

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IZZI...

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
825 AM CDT TUE JUN 25 2013

.MESOSCALE DISCUSSION...
826 AM CDT

SMALL MCS WITH BOWING LINE SEGMENT CONTINUE TO RACE EASTWARD ALONG
THE IL/WI BORDER. DESPITE WHAT HAS BEEN A VERY IMPRESSIVE RADAR
SIGNITURE FOR DAMAGING WINDS...THUS FAR THE WINDS HAVE NOT BEEN
PENETRATING TO THE SURFACE. THIS SMALL COMPLEX IS WELL NORTH OF
LAST NIGHTS OUTFLOW BOUNDARY AND WOULD APPEAR THAT BOUNDARY LAYER
STABILITY IS STRONG ENOUGH KEEP WIND THREAT ELEVATED FOR AT LEAST
ANOTHER HOUR OR TWO...LIKELY LONG ENOUGH FOR THIS SMALL BOW TO
MAKE IT TO THE LAKE. ADDITIONAL THUNDERSTORMS DEVELOPING OVER
NORTHWEST ILLINOIS ARE DEVELOPING CLOSER TO THE OUTFLOW BOUNDARY
AND MORE UNSTABLE AIR MASS AND SHOULD THESE STORMS INTENSIFY THEY
WOULD STAND A BETTER CHANCE OF POSING A SEVERE WEATHER RISK LATER
THIS MORNING.

 

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Thankfully it is 830AM and not 230PM.

 

 

you have to actually read, Stebo

 

 

 

the only thing I'm downplaying is this crappy morning MCS. Evening is still up for grabs.

 

 

I don't see any signs of prolonged destabilization in the near term

 

 

I mean, come on dude.

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