Cindy_Fitzgibbon's Blog

Morning....

"BrooklineRSfan" asked a question about El Nino or La Nina on my last post... so I thought I'd create a separate blog for it here.  Here's what he asked:

Are we currently in a sort of El Nino or La Nina? It seems precip has been above normal for quite a few months, but the temps haven't swayed too far one way or another. Also, I've found the storms to be more frequent, too (resulting in the greater precip totals). It feels like we haven't gone more than 2 quiet days before another storm is upon us, with many Tues/Wed and Fri/Sat storm patterns. Or is this just a case of an active jet stream?

We actually are in a La Nina pattern right now... it started during the second half of 2007 and is expected to continue through at least the spring.  There are signs though just in the past couple of weeks that it is starting to get weaker. 
Here's a link to current SST from the Climate Prediction Center http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJ
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La Ninas typically last 8 months to up to 2 years.   Our active weather pattern as of late does indeed have to do with the jet stream being so close by... which relates to La Nina.

Just a quick synopsis of La Nina/El Nino for those that aren't sure:  These terms refer to Sea Surface Temperatures (SST) in the equatorial Pacific.  The full term is ENSO- or the El Nino Southern Oscillation- indicating that the SST oscillate back and forth either side of what is considered 'normal'.  La Nina is when they are colder than average (happens when persistent stronger winds in this region create what's called 'upwelling' or drawing colder water from below to the surface).  El Nino is when SST are warmer than average (happens when the winds relax allowing surface to heat up).  Warmer or colder SST in turn change 'normal' weather patterns in this region (warmer =more storminess- warmer moist air rises, cools, condenses.... colder= less storminess) which in turn can change weather patterns around the globe. 

The past few months have been classic La Nina weather in the U.S. - partcularly with all the flooding in the Ohio Valley region.  For us... La Ninas often bring more precipitation in the colder months with no strong temperature signature.  Indeed, we've had a decent amount of rain (and snow) with temperatures near average (especially in Feb and March).  La Ninas though, seem to have a more pronounced impact on our local weather during the winter months than they do in the spring heading into the summer.  Here's a link to  the climate prediction center with a map showing global impacts for the winter and summer months
http://www.cpc.ncep.noaa.gov/products/analysis_monitor
ing/impacts/cold.gif 

The longer range forecast (90 Day Outlook- April, May, June) from the Climate Prediction center also calls for us to have near normal weather conditions during this time period with no significant swings above of below average for temps or precip.  Here's a link:

http://www.cpc.ncep.noaa.gov/products/predictions/m
ulti_season/13_seasonal_outlooks/color/page2.gif>

So no real obvious clues from La Nina as to what lies ahead this spring.  I can tell you that I see another rain event Fri into Sat with lighter showers possible next Monday/Tue and again Thursday... It looks to remain fairly active for the next 10 days.  Beyond that... I guess we'll just have to wait and see.

Have a great day!
Cindy