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June 15-18 Severe Weather


Chicago Storm

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18z GFS is definitely more aggressive than the NAM with a compact, organized s/w (and resulting SLP) and a near 70 kt H5 jet streak across northern MO nosing into IL on Saturday afternoon/evening, might be some convective feedback issues with it though, looking at some of the vorticity and sfc precip forecasts on COD's page.

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Would not rule out some isolated tornado potential on Saturday in the eastern IA/northern-central IL area. Degree of destabilization is a bit more in question compared to the last event, but models have decent instability/shear parameters in the afternoon and evening, and the NAM in particular has some very good turning with height.

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DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1229 PM CDT FRI JUN 14 2013

VALID 151200Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE LOWER MO

VALLEY AND MID TO UPPER MS VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL HIGH

PLAINS...

...LOWER-MO VALLEY/MID TO UPPER MS VALLEY...

AN UPPER-LEVEL RIDGE WILL DEAMPLIFY ON SATURDAY AND MOVE EWD INTO

THE GREAT LAKES REGION AND OH VALLEY. AT THE SFC...A COLD FRONT IS

FORECAST TO ADVANCE SEWD INTO THE MID TO UPPER MS VALLEY. ELEVATED

THUNDERSTORMS MAY BE ONGOING SATURDAY MORNING IN IA...IL AND WI NEAR

THE NOSE OF THE LOW-LEVEL JET. THE MODELS MOVE THIS ACTIVITY SEWD

INTO THE LOWER OH VALLEY AND DEVELOP A CLUSTER OF SFC-BASED

THUNDERSTORMS ALONG THE FRONT ACROSS IA AND NRN IL SATURDAY

AFTERNOON. SOME OF THE MODELS SUGGEST A LINEAR MCS WILL ORGANIZE AND

MOVE SEWD ACROSS THE SLIGHT RISK AREA DURING THE LATE AFTERNOON AND

EARLY EVENING.

FORECAST SOUNDINGS AT DAVENPORT IA AND SPRINGFIELD IL AT 00Z/SUN

SHOW SFC DEWPOINTS NEAR 70 F WITH MLCAPE VALUES OF 1500 TO 2500

J/KG. O-6 KM SHEAR IS FORECAST TO RANGE FROM 30 TO 40 KT BUT SHOULD

INCREASE DURING THE EARLY EVENING AS A MID-LEVEL JET DEVELOPS TO THE

WEST. THIS ENVIRONMENT SHOULD SUPPORT SEVERE STORMS BUT STORM MODE

IS THE MAIN QUESTION. IF CELLS INITIATE AND REMAIN DISCRETE...THEN

SUPERCELLS WILL BE FAVORED WITH LARGE HAIL AND A FEW TORNADOES

POSSIBLE. HOWEVER...A QUICK TRANSITION TO A LINEAR CONVECTIVE SYSTEM

WILL FAVOR WIND DAMAGE AS THE PRIMARY THREAT. THE GREATEST SEVERE

THREAT SHOULD BE LOCATED NEAR THE STRONGEST INSTABILITY AND ALONG

THE AXIS OF THE MID-LEVEL JET...CURRENTLY FORECAST TO BE FROM NRN MO

EXTENDING ENEWD ACROSS SE IA INTO WCNTRL IL.

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Looks like the action is going to be south of 88.

But if we can get some sun and destabilize, it could fire up here. And some later towards the night.

Just need some sun to have a decent chance tomorrow. I havent looked into it yet, but I think the stuff in Iowa might be a problem in the morning for that

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Looks like the action is going to be south of 88.

But if we can get some sun and destabilize, it could fire up here. And some later towards the night.

Just need some sun to have a decent chance tomorrow. I havent looked into it yet, but I think the stuff in Iowa might be a problem in the morning for that

 

 

00z Nam Hires has stuff hitting all of northern IL.

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Man today's setup is a big challenge.  There's leftover boundaries all over.  Pockets of overturned lapse rates.  Ongoing/festering convection in areas.  Northern Missouri and southern Iowa are getting some decent sun right now.  Don't think that area had much activity last night either.  RAP shows a nice H5 speed max of 50+kts moving over that area later this afternoon.  Forecast soundings in that area look decent.  That will probably be the best area to head for tornadic potential IMO. 

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Complex of storms organizing in northern Iowa will probably roll east, and then east-southeast later today.  Could impact much of northern IL, including Chicago later today. 

 

Interesting looking thin line of elevated hailers from south of Peoria up towards Cedar Rapids.  Updrafts are small, but have reached as high as 40kft.  This line may try to become surface based over the next few hours as surface heating continues upstream. 

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Nice update from our very own RC.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

215 PM CDT SAT JUN 15 2013

MESOSCALE DISCUSSION

215 PM CDT

CONTINUING TO MONITOR CONVECTIVE TRENDS EARLY THIS AFTERNOON. STILL PLENTY OF UNCERTAINTY REGARDING EXTENT OF SEVERE THREAT BUT CURRENT SATELLITE AND SURFACE OBS AND MESOANALYSIS GIVE SOME HINT AT HOW THINGS MIGHT PLAY OUT. MCV ASSOCIATED WITH LATE MORNING COMPLEX CURRENTLY PIVOTING SOUTHEAST FROM EASTERN CWA...WITH BREAKS IN CLOUDS DEVELOPING ON BACK SIDE OF MCV. EASTERN HALF OF CWA IS QUITE STABLE INITIALLY...BUT RECOVERY OF DEWPOINTS INTO MID AND UPPER 60S INTO WEST AND SOUTHWEST CWA...ALONG WITH TEMPERATURES ALREADY WARMING INTO UPPER 70S TO AROUND 80 HAS RENEWED DESTABILIZATION PROCESS FOR THESE AREAS. RAP IS MOST BULLISH/LIKELY TOO BULLISH ON MLCAPE VALUES BY LATE AFTERNOON...BUT EVEN NAM SUPPORTS MLCAPES OF ABOUT 1000-1500 J/KG BY LATE AFTERNOON OVER THE WESTERN CWA...WITH MINIMAL TO NO CAPPING BY THEN AND ONLY MINIMAL CAPPING RETURNING BY EARLY EVENING.

EXPECT THE COMPLEX OVER WEST CENTRAL ILLINOIS TO BE STEERED SOUTH OF THE CWA...WITH THE LIKELY FOCUS FOR ROBUST DEVELOPMENT IN THE LATE AFTERNOON INTO THE EVENING TO BE THE WAVE NOTED ON W/V AND RADAR OVER NORTH CENTRAL IOWA. HI RES MODELS SUCH AS SPC-WRF NMM AND HRRR SEEM TO HAVE A DECENT HANDLE ON TRENDS AND SHOW CLUSTER OR CLUSTERS DEVELOPING SOUTH OF THE CURRENTLY WEAKENING CONVECTION OVER NORTH CENTRAL IOWA OVER EASTERN IOWA AND NORTHERN MO. THESE THEN FOLLOW THE 850-300 MB THICKNESS LINES EAST OR EAST-SOUTHEAST FROM WESTERN ILLINOIS BY THE LATE AFTERNOON AND EARLY EVENING (23Z-01Z) TO NORTHEAST IL AND NORTHWEST INDIANA A FEW HOURS LATER (02-04Z).

0-6 KM BULK SHEAR STRENGTHENING TO 40 TO AS MUCH AS 50 KT BY EARLY EVENING WILL SUPPORT ORGANIZATION...AND INCREASING LOW LEVEL JET/0-3 KM SHEAR COULD RESULT IN DAMAGING WIND THREAT. ALSO...MID LEVEL LAPSE RATES STEEPENING FROM THE WEST WITH APPROACH OF WAVE COULD PRESENT A SEVERE HAIL THREAT...MAINLY FOR NORTH CENTRAL IL AND POINTS WEST. THINK THAT COMPLEX WILL BE ON WEAKENING TREND AS IT HEADS EAST INTO NORTHEAST IL AND NW INDIANA DUE TO LOWER AND DIMINISHING INSTABILITY BY THAT TIME...BUT STILL CAN FORESEE LIGHTNING AND GUSTY WINDS AFFECTING OUTDOOR EVENTS OVER THESE AREAS. IN ADDITION...MORE INTENSE STORMS TODAY OVER REGION HAVE PRODUCED VERY HEAVY RAINFALL WITH PWAT OVER 1.5 INCHES AND WITH 850 MB MOISTURE TRANSPORT INCREASING THIS EVENING...IMPRESSIVE RAINFALL RATES AND LOCALIZED FLASH FLOODING ARE CERTAINLY POSSIBLE. FINALLY...SOME CONCERN THAT THE INCREASING 850 MB MOISTURE TRANSPORT AND FLOW COULD ALSO MAINTAIN SEVERE THREAT FARTHER EAST THAN CURRENTLY EXPECTED...SO WILL CONTINUE TO MONITOR THIS POSSIBILITY AS WELL. THIS IS SOMETHING THAT THE LATEST 17Z HRRR SHOWS.

RC

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I thought there would be some hope for today given how far east the MCS was by late last night...but obviously that's not the case.

 

It doesn't help that ouside of the HRRR the models have not had a clue on what's going on...and they still don't.

 

Looks fairly meh...Still would like to get in a lightning photo op tonight though.

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Subtle wave/boundary trailing into Des Moines has a small cell in Lafeyette Cty (sw Wisconsin). We'll see if that can sustain moving to the ESE perhaps. It also seems the marine influence off LM might be making itself known, as expected per SLT risk boundaries, in extreme NE IL.

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Chances are more numerous sub severe storms will develop with the wave moving eastward toward Lake Michigan.  Hopefully can get a couple of boomers with that.

 

Looking more interesting on the radar now. 

 

RPM showing so healthy storms down this way later on.

 

10605_10151651221871760_1428407248_n.png

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That was an old run though geos. Not a total bust of a tstorm forecast though.

 

Ok, I'm not sure where to find the new runs. That's what Skilling posted on his wall 11 hours ago. 

 

Looks like this area might shoot the gap though.

 

Nevermind - some cells popping to the west of here now.

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Ok, I'm not sure where to find the new runs. That's what Skilling posted on his wall 11 hours ago. 

 

Looks like this area might shoot the gap though.

 

Nevermind - some cells popping to the west of here now.

 

I think most on this subforum in the Milwaukee, Madison, Chicago areas will get some decent storms, at least nearby to hear some boomers and see some flashes.

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Ended up heading into southeast Iowa around Mount Pleasant.  Storm was severe warned and did have some weak mid-level rotation for a time.  By the time I got there it was clearly outflow dominant.  Did have a nice bowing shelf cloud with it though.  Put out quite a few CGs as well.  Nothing spectacular, but sort of a fun backyard chase.

 

5pr.png

 

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DTX throws us a nice, juicy-looking bone for tomorrow...

 

 


000
FXUS63 KDTX 161956
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
356 PM EDT SUN JUN 16 2013

 

.LONG TERM... MONDAY THROUGH SUNDAY

AFTERNOON WATER VAPOR SATELLITE IMAGERY AND SURFACE ANALYSIS
INDICATE THE UPPER LEVEL TROUGH SHEARING SOUTHWARD FROM CENTRAL
CANADA AND CARRYING THE ASSOCIATED COLD FRONT INTO THE UPPER
MIDWEST. THIS SYSTEM WILL BE THE FOCUS OF CONDITIONS IN SE MICHIGAN
MONDAY AND MONDAY NIGHT AND PRESENTS A FAIRLY STRAIGHTFORWARD
FORECAST SCENARIO FOR SHOWERS AND THUNDERSTORMS. AT FIRST, IT LOOKED
LIKE BOUNDARY LAYER MOISTURE RETURN WOULD BE ONE OF THEM BUT PERHAPS
NOT CONSIDERING HOW CONVECTION IS DEVELOPING TODAY OVER THE NORTHERN
GREAT LAKES. LOWER 50S SURFACE DEWPOINT IS GOOD ENOUGH IN THAT
AREA WHERE TEMPERATURES ALOFT ARE ABOUT -16C AT 500 MB. THERE IS
GOOD AGREEMENT AMONG THE NEW MODEL OUTPUT SHOWING SOME OF THIS
COLD AIR ALOFT SETTLING OVER SOUTHERN LOWER MICHIGAN BY MONDAY
AFTERNOON TAKING 500 MB TEMPS DOWN TO BETWEEN -14 AND -16C. EXPECT
THIS WILL PERMIT LOWER TO MID 50S SURFACE DEWPOINT TO GENERATE
CAPE AROUND 1500 J/KG, GOOD ENOUGH FOR CONVECTION TO BECOME
ORGANIZED WITHIN A STRONG WIND FIELD FEATURING NEARLY 60 KNOTS OF
WESTERLY FLOW AT 500 MB AND 45 KNOTS OF 0-6KM BULK SHEAR. THE
STRONG UNIDIRECTIONAL NATURE OF THE SHEAR PROFILE INDICATES A
DISCRETE SUPERCELL MODE IS POSSIBLE EARLY WITH ENHANCED UPDRAFTS
CAPABLE OF LARGE HAIL DUE TO FREEZING LEVEL ON THE LOW SIDE,
ABOUT 10500 FEET, FOR THIS TIME OF YEAR. A QUICK EVOLUTION INTO A
LINEAR MODE COULD FOLLOW WITH A DAMAGING WIND COMPONENT.

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It will be interesting to see how storms initiate tomorrow. I'm concerned about lower level moisture especially after seeing how well things mixed out today. But with the cold front sagging south along the lake shore in the afternoon maybe we can get a nice cell riding along the area of convergence.

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