Does a Wet Winter = More Severe Spring?

[Michael Rogers]

Hello everyone. I would have put this in the educational section for beginners (as I definitely am one), but it seems I don't have "rights" to post there.

We've received much more precipitation than usual here in the Chicago area and it got me to thinking. Does a wetter winter cause for a potentially more severe spring? I remember a couple years where we've had a very dry winter. In early spring, it seems all the storms die out quickly once they reach the drought area due to lack of moisture. Is this just a coincidence? I'd think severe thunderstorms would draw moisture on a much larger scale than a metropolitan area. But it seems that if there were more moisture available in our lakes, wetlands, soil, etc. than the added moisture would be more beneficial for severe storms so long as all other aspects of a severe storm are present. Whereas if we are dry, it could "starve" the storm of moisture.

I hope I've made sense in all that. Any feedback?

 

[Mike Smith]

In an "every other factor equal" situation, the severe weather in the Plains would probably be farther west than otherwise due to the dry line not racing as far east.

 

[Scott Weberpal]

Evapotranspiration (the release of moisture from plants/soil into the atmosphere) can play a role by increasing the overall moisture content of the local atmosphere. Typically evapotranspiration yields a shallow layer of increased moisture, but over extended periods of time can yield enough moisture to make a difference in maintaining high levels of deep moisture needed for convection.

On the other hand, if there is little or no surface moisture available for evapotranspiration (ie very dry winter and spring), moisture advected from the gulf, if shallow enough, will mix out relatively quickly leaving you with a dry boundary layer.

Please don't insinuate that ET is going to be a saving grace with ample surface moisture, a good fetch of deep gulf moisture is the first thing you want no matter how moist or dry the surface is.

To answer your question, yes, having a wetter than usual winter or spring can influence the severity of storms. You are much more likely to maintain decent BL moisture in and environment with shallow gulf moisture and ample moisture for ET than you are in an environment with shallow gulf moisture and little or no moisture available from ET.

 

[Gerrit Gulden]

Because I do not live in the plains and am on the left side of the rockies (gulf moisture is blocked out), My winter has been extremely long and very wet (white), does the theory of a More severe spring/summer still come into play for The Northwest? I certainly hope so. That would mean more lightning for me to shoot and better structure. =)

-gerrit

 

[Greg McLaughlin]

"Does a wet winter = more severe spring?" It would be nice if it did, however I try not to put hope in such ideas. There is no real way to determine if we will have an above average severe weather season from one year to the next. There are so many factors that go into developing a pattern condusive for severe weather (especially tornadoes) it is impossible to know more than few days in advance (at best a week or so) if we will be in an active pattern.

 

[Chris Bowman]

I think Mike hit the nail on the head. I would also add that "every other thing being equal" higher soil moisture and higher evapotranspiration rates may add to the available low level moisture slightly which likely feeds back to what Mike said.

 

[rdale]

The problem is that "every other thing being equal" part of the equation...

 

[Bob Schafer]

Not too long ago, someone suggested to me that the Rocky Mountain snowpack, especially in CO, has a significant impact on severe wx in The Alley. I wish I could credit that person, but I no longer have a clue who it was.

The hypothesis is that the greater the snowpack, the cooler the 700mb temps will remain over the central USA throughout the severe wx season, since the air that flows over the mountains apparently ends up more or less at about the 700mb level once it advects eastward. Of course, cool 700mb T's tend to lead to greater instability.

Right now, there is some buzz here in CO about the potential for snowmelt flooding in the next couple months because the snowpack is so deep this spring.

 

[Laura Duchesne]

The way I look at it is... if it gets real hot, the strong sun will just evaporate the moisture out of the ground eventually anyways... so I usually don't put too much faith in such theories.

While out chasing last Friday, we noticed some of our fields here have turned into mini lakes. Perhaps if there is enough moisture, maybe it could help out a bit but it's still uncertain.

 

[J.K Oudshoorn]

Guess these things are more theories. it's not a smart idea to put your hope on this.. as it is not really proved to get more severe weather when the winter is very wet?

Are there any articles about this?

Regards,

Koos

 

[rdale]

No, because it's too vague of a theory to be studied...

 

[Adam Lucio]

This is from an article on an event that Happened in July of 2004 where a lone supercell formed over northwestern IL and went on to produce 4" hail and a couple tornadoes...

"Evapotranspiration was likely a dominant contributor to the warm dewpoints due to the extensive corn fields in the area. The corresponding CAPE values as calculated at the SPC revealed a maxima of over 7500 J/kg coincident with the highest dew point air."

Heres the link, as mentioned in the article, many other key ingredients were in place, tho ET alone probably wouldnt brew up such a storm, it certainly can add fuel to the fire.

http://www.crh.noaa.gov/lot/science/13Jul2004/index.php