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NUTTY EAST COAST JUNE WEATHER
Is El Niño to Blame?
By:
Mike Watson
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In the last installment ,
we addressed the issue of what constitutes a normal hurricane season in the Atlantic Ocean and where we generally expect storms to form and track on a month-by-month basis. We alluded to the fact that we have a developing El Niño and indeed, on July 9th NOAA announced that we are now officially in the warm ENSO state known as El Niño.
A very astute and obviously frustrated surfer Robert Gannon writes: |
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"We deserve an explanation. You almost gave us one for the January to mid-February flat spell. This one's about to start week seven. It was fun for one afternoon, June 18th. Other than that, we've had absolutely nothing. Do not play the summer or Florida card. Something is wrong. Like Eskimos and snow, we have 40 different words for flat and the fish derivatives to make flat rideable. This is not our normal flat, broken up by extremely marginal but manageable trade dribble. Usually the onshore is up by 10:30am. It's been WSW or SW wind all day every day for weeks. This is not normal. This summer is different. Why is there no seabreeze? Why is the Bermuda High depressed so far south? Obviously it's impossible to say when it will change, but could you offer insight on to what exactly must take place (jet stream change, etc.) so we can think the proper thoughts when we burn boards, groms, etc. in sacrifice? We deserve an explanation. Many thanks." Being in Florida myself, I too share the frustration of Mr. Gannon and I too want to know just what in the hell is going on. So I dug in and did some research and came up with some very interesting results. "Like Eskimos and snow, we have 40 different words for flat and the fish derivatives to make flat rideable." - Robert Gannon
I used data from the NCEP Reanalysis project; this data is widely used in scientific peer reviewed studies and very much suitable for this study. The data is gridded every 2.5 x 2.5 degrees; the long-term means for both pressure and wind use calculations from years 1948 through 2008. The June 2009 means are calculated using the same 2.5 x. 2.5 degree gridded data and compared to the long-term mean. For the pressure plots, I subtracted the June 2009 average daily surface pressure from the long-term daily average June surface pressure. This gives us our pressure anomaly which is the departure from average. For comparison, the ambient average mean sea level pressure for the earth is 1013mb - thus anything larger than that can be regarded as high pressure and anything lower can be regarded as low pressure. For the wind plots, I simply plotted the long-term mean and the average daily June 2009 wind. The first pressure plot shows the long-term mean surface pressure for June. The average location of the Atlantic ridge is centered towards the east-central Atlantic. The ridge extends well over much of the East Coast and into the Gulf of Mexico towards the Texas coast. The second pressure plot shows what we have seen in June 2009 - the center of the ridge is centered further west and south than the long-term average. The extent of the ridge is attenuated with the western extension only just nudging in over the Florida peninsula. The pressure anomaly plot really tells the rest of the story: over the eastern Atlantic towards Europe there are large negative pressure anomalies. This means that this region of the Atlantic has seen much lower pressure than what would be expected - up to 7mb below the average which is very significant! As we look westward over the East Coast and Florida, we can see that there also exists a rather large region of lower than normal pressure anomalies up to 3mb below normal which is also fairly significant. Also the extent of this anomaly is large with values of negative 2mb out to 60W, extending westward over the Gulf of Mexico. This nicely depicts our abnormal June with an East Coast trough generally remaining in place. We even saw a rare June northeaster that developed early in the month, dumping heaps of rain on golf's U.S. Open held on Long Island. It should be noted that while Florida has suffered a lengthy flat spell (with only a brief but fun swell for North Florida on July 10th-12th), this pattern has put some fun surf in the water for surfers in the Northeast region and even some fun days in the Southeast region as well. The wind plots finish off the story. The long-term average meshes well with our long-term average June pressure plot. Upon inspection of our plots, winds over the Florida peninsula average S/SE direction in a normal year. However in June 2009 we saw predominantly SW winds which matches up well with the average pressure field from our displaced Atlantic ridge. Now the question remains: why has this pattern taken shape? Well one potential answer is tied into El Niño. We have been in a positive phase of climate variability known as PNA or Pacific-North American teleconnection during the month of June. One result of this pattern is lower than normal surface pressures along the southeast US, which, by the data I have provided, we can clearly see has been the case. This positive PNA phase is generally associated with the warm phase of ENSO or El Niño. It is highly likely that the onset of El Niño over the past few months (El Niño does not just magically 'appear,' it takes time to develop) has resulted in the positive PNA pattern which has resulted in lower surface pressures over the East Coast and a displaced Atlantic ridge. So one more question remains - what does this mean for our Atlantic tropical season? I still think it is too early to tell but what we can examine further is El Niño and why this warm ENSO phase is associated with less tropical activity in the Atlantic basin. For the third installment in this series we will examine El Niño and the atmospheric circulation changes that occur as a result of this phenomenon. Pacific North American (PNA) image courtesy - Climate Prediction Center Reanalysis Data courtesy - Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470, 1996 MORE FORECAST SURFLINE HOME PAGE |
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Comments: (13) Add Your Comment
L 07/17/2009 11:13 AM
well the gulf side of FL has had unexpected fun surf.. end last weeks of june-1st week o july!..
Daniel Williams 07/17/2009 07:28 AM * PREMIUM MEMBER - Real Name
In case anyone forgot...
SURFING IS A WINTER SPORT!!!!!!
Daniel Williams 07/17/2009 07:26 AM * PREMIUM MEMBER - Real Name
Summer flats = Fall swell.... even on the East Coast. Be patient grasshoppers.
Crabbie 07/17/2009 06:24 AM
Skim boarding has become the flat summer time fix down here in South Florida. Kite surfers have had no good wind to ride too. time to go on a surf trip...
boz 07/17/2009 02:18 AM
I can explain the flat surf misery, it's because I just moved back east from 6yrs in the desert, bought a new longboard and didn't pay homage to the wave god ;)
Wolly Crookwell 07/16/2009 11:14 PM
There is no god. Atlantic summer flatness is utterly heartbreaking.
thor 07/16/2009 02:19 PM
Here's the secret for surf-starved east-coaster's: move
Tom in LB 07/16/2009 01:29 PM
Cold water temps and flat surf have plagued NY/NJ for months, I haven't seen this poor of a spring/summer in years. Here's to hoping the Fall delivers
flat-in-SC 07/16/2009 08:54 AM
We've had unusually high tides this summer as well in South Carolina--- could the lower sea surface pressures mentioned cause this?
editor reply:
No - this would have a negligible effect if any on the tides.
CABEZA 07/16/2009 06:55 AM * PREMIUM MEMBER - Nickname
Maybe you should make the same analysis for the 97-98 season when the last Niño occured and compare the results with the ones from june 2009. That might give us an idea of what to expect from the current anomalies.
Dude 07/15/2009 03:15 PM
plenty of surf this summer on south facing NC beaches. Sucks for you
Pete 07/15/2009 02:57 PM ** EDITOR'S PICK
2 words - "Surf Trip"
alex 07/15/2009 02:22 PM
let us know as soon as you can how this will effect the coming months as far as tropical activity. cause i have august off and i am debating buying a ticket to cali or chancing it for some storms in FL
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