great lakes and storms

[Danny Neal]

well im not exactly sure about the other lakes but i know living on the southside of chicago, that anytime severe weather moves into the area 7 out of 10 times the lakes influences help kill the storm, first of all is this because of the storms inflow sucking the cooler air off the lake and secondly do you think that one day the lakes will warm up enough for this not to happen?

Dan Neal

 

[Justin Turcotte]

The lakes can work both ways. Since the lakes are generally cooler than land at peak heating during the convective season you get that lake breeze circulation. The lake breeze creates a zone of convergence which can actually help initiate or enhance convection. Since the cool side of the sea breeze front is more stable it makes sense that surface based storms that cross the boundary would tend to weaken though they may experience a brief period of intensification right along the boundary. I suspect the lakes are not as significant a factor for strong to severe elevated convection that is moving into the area.

To answer the latter question: No. If the water temp is heating up from global warming then the land would heat up too. The air over the lake will always be more stable during the warm convective season barring some extremely odd weather scenario.

 

[Danny Neal]

ahh i see thanx for the reply, yeah because i have lived here all my life and it seems more often than not all the counties besides Lake and Cook County(chicago) have seen severe weather but it seems once it gets to that zone a town maybe 10 miles from me will report a severe wind but by the time it reaches me its little more than a garden variety thunderstorm with 30 mph winds, ive also noticed that most of the storms around my neck of the woods are MCS forms that hit between 10PM - 4 AM, so im sure lack of heating is another factor, i just find it wierd how storms tend to die late at night around my area and by the time daytime heating hits the next day the storms flare up 30-50 miles to my south and east, so i always figured the lake killed night time storms even on the huge outbreak on march 12th the town of bridgeview which is literally 5 miles west of me had 80 mph downburst winds which caused a 3 block swath of damage but when it reached here no later than 5-10 mins later we had a couple of close flashes of lightning and flooding rain so with that being said i guess i was under the impression that the lake inflow especially late at night aided in killing the severity of the storm

 

[David Draun]

Every once in a while, the lake breeze will help to trigger severe weather, this can be especially true with a backdoor cold front dropping south out of Wisconsin, or a stationary front waving across the Chicago metro area. The boundaries may intersect, allowing for strong convergence and lift, especially on a hot, humid summer afternoon. Flooding rains are a common result due to echo training eastward over the same area, with little southward progress. Hail and high winds can also occur. I'm not sure if tornadoes have occured in this scenario, but I wouldn't rule one out. Correct me if I'm wrong, but I seem to remember a theory where a lake induced boundary may have been an ingredient to tornadogenesis on August 28th 1990.

Many supercell storms rely on warm moist inflow from the S or SE to maintain their strength. The lake breeze contaminates the inflow, making it cooler and causing the storm to weaken.

On days with strong SWly surface flow, the lake is not much of an issue, however. Maybe the issue is the timing of convection? I've noticed many storms reaching this area long after initiation, and they are usually linear or multicellular. In most weather systems I've seen, storms fire well to the west and have time to evolve into a different convective mode before they reach the metro area.

 

[Danny Neal]

Every once in a while, the lake breeze will help to trigger severe weather, this can be especially true with a backdoor cold front dropping south out of Wisconsin, or a stationary front waving across the Chicago metro area. The boundaries may intersect, allowing for strong convergence and lift, especially on a hot, humid summer afternoon. Flooding rains are a common result due to echo training eastward over the same area, with little southward progress. Hail and high winds can also occur. I'm not sure if tornadoes have occured in this scenario, but I wouldn't rule one out. Correct me if I'm wrong, but I seem to remember a theory where a lake induced boundary may have been an ingredient to tornadogenesis on August 28th 1990.

Many supercell storms rely on warm moist inflow from the S or SE to maintain their strength. The lake breeze contaminates the inflow, making it cooler and causing the storm to weaken.

On days with strong SWly surface flow, the lake is not much of an issue, however. Maybe the issue is the timing of convection? I've noticed many storms reaching this area long after initiation, and they are usually linear or multicellular. In most weather systems I've seen, storms fire well to the west and have time to evolve into a different convective mode before they reach the metro area.
[/b]

Hey, yeah thats what im saying tho, i just wasnt clear on why it seems my local area practically gets nothing while the suburbs further away from the lake seem to be getting most if not all of the action, maybe i should move to the mini - alley down by peoria and enjoy! And the plainfield tornado is really what got me hooked because it happened 10 miles from my house and i have vivid memories of my dad who is a local fireman, telling my family to get down to the basement and then him leaving to do triage, but thanks for the input i just want to be clear on this issue and i had the idea about the storms inflow from the S SE but i didnt post it because i didnt wana be completely wrong bout it, I remember back on August 1st of 2003 when the lakebreeze fired up a big multi cell cluster over the city and dropped a funnel cloud in justice but then again i remember all the supercells on may 30th 2003 i think on the NWS website they were storms A B C, but how the second they made it into the CWA by the lake they became linear or else weakened completely

 

[Dan Robinson]

Interesting topic. So are there a known synoptic setup that is favored for thunderstorms to maintain their strength across the Chicago metro? I'm assuming you'd need the lake breeze front to be either close to the shoreline or weak/nonexistent, so that storms moving over town would not start pulling in the stable lake air at the surface until they were actually over the lake.

Maybe a decent southwest flow at the surface to keep the lake breeze from pushing too far inland?

 

[rdale]

Correct - any good wind from the west will do. But much of our area's "severe" weather (as in 58.1mph winds and 0.751" hail) come from weakly forced days which is when the lake has a BIG influence.

 

[Robert Dewey]

I guess it depends on storm mode and motion when crossing the lake.

I suspect that if a storm is slow moving and being driven predominately by instability, it will weaken over the lakes. If a storm is slow moving but is driven by dynamics (or feeding on elevated instability), it's less likely to weaken.

On the other hand, if you have a fast moving line (May 31st, 1998 derecho @ +70MPH), it crosses the lake rather quickly, so the effect is small. In fact, during that particular derecho, there were a few >130MPH reports (and many >90MPH reports). That system was driven primarily by dynamics and moderate instability (LI's were around -6C I believe).

 

[David Draun]

The marginally severe storms that dropped out of WI on the evening on the 28th seemed to be ehanced by a lake breeze front. On the radar display, weakening storms encountered the lake boundary and re-exploded.

 

[Danny Neal]

the lake breeze boundary usually is a N-S oriented line with a bulge thru the center as seen on KLOT, it seems to me that almost anytime of the storms being inhanced by the boundary they are travelling North To South or Even Northwest to Southeast, what i dont understand is how this rarely if ever works for a SouthWest to NorthEast or West to East moving storm, does it have to do with the storms riding the boundary to enhance svr weather potential and to diminish it does it have have to do with a westward moving line sucking in the cool air on the otherside of the boundary as the boundary runs into it? the 28th as i left for my job it seemed like the storms were diminshing and i thought we were getting a shower until a large gust front with vivid lightning was visible...........just wondering if anyone else noticed or had a thought about the boundary

 

[Tony Lyza]

This storm might be the PERFECT example of lake breeze enhancement. This formed on 7/17/03. That day was dominated by multicellular convection (a normal ring-of-fire day). This storm hit a weak lake breeze and absolutely EXPLODED. As it hit my house, we had downburst/microburst winds of 90-100 MPH and golf-ball with isolated tennis-ball-sized hail CONCURRENTLY. It stands today as one of THE most severe non-tornadic storms in this area's history.

p.s. On that image, the arrow should be pointing a bit more southerly. It's hard to mark storm movement on a still image without a zoomed-in loop off of memories from three years ago. Everything else is correct. The meso was beginning to occlude; a funnel cloud was sighted seven miles due south of "me", and the storm was moving SE; the new meso formed due south of the location in the image. The storm was becoming outflow dominant gradually; by the time it reached the southern end of Lake County, it was outflow dominant and quickly merged with other storms to the SE to form an MCS.

 

[Danny Neal]

that storm knocked down 100-200 trees in my town had gusts i clocked easily over 70 mph i live across the street from a cemetary and all i remember is a whooshing noise and then tree after tree going down, one of those trees barely missed my car.......weird thing was they issued a svr for my town AFTER the storm hit

 

[Tony Lyza]

We had a TOR on that storm (for good reason as you can see). I don't know exactly what kept it from producing. My first guess would be LCLs; however, I can't remember the specific conditions that day.

 

[Laura Hedien]

Here's a thought by SPC regarding today..... note the end of the paragraph!!

" ...UPPER MS VALLEY/GREAT LAKES...
FRONTAL ZONE WILL DEVELOP EWD/SEWD INTO INCREASINGLY UNSTABLE AIR
MASS FROM WI/UPPER MI TO LOWER MI AND SWRN ONTARIO. GREATER LOW
LEVEL MOISTURE ADVECTING ENEWD FROM THE CORN BELT COUPLED WITH
DIURNAL HEATING WILL CONTRIBUTE TO THE DEVELOPMENT OF MODEST
INSTABILITY /MLCAPE 1000-1500 J/KG/ AS THE SHORT WAVE TROUGH AND
FRONT APPROACH DURING THE AFTERNOON. LOW THROUGH MID LEVEL FLOW WILL
INCREASE THROUGH THE DAY AND LEAD TO MORE THAN SUFFICIENT SHEAR FOR
ORGANIZED STORMS. LINEAR FORCING WITH THE FRONT SUGGESTS POTENTIAL
WILL EXIST FOR LINE SEGMENT/BOW ECHO FORMATION WITH THE WIND DAMAGE
THREAT INCREASING FROM WI ACROSS LOWER MI THROUGH THE AFTERNOON AND
INTO THE EVENING. SUPERCELL TORNADO AND LARGE HAIL POTENTIAL CANNOT
BE RULED OUT WITH FORECAST SOUNDINGS DEPICTING INCREASINGLY STRONG
LOW LEVEL FLOW AND EFFECTIVE SRH VALUES IN EXCESS OF 200 M2/S2
ACROSS WEAKLY CAPPED WARM SECTOR. LAKE BREEZE BOUNDARY/CELL
INTERACTIONS MAY ALSO LOCALLY ENHANCE THE CHANCE FOR BRIEF
TORNADOES."

http://spc.noaa.gov/products/outlook/day1otlk.html

I just thought that an interesting thing based on this particular discussion the last few days.
I live about 11 miles from Lake Michigan also....
Laura

 

[Dan Cook]

I remember that day. My dad got bombarded with hail coming home from work while here in Lombard we got nothing.