Un récent rapport des spécialstes fait état de l'émergence de La Nina récemment. Comme ce phénomène a d'importantes conséquences sur le climat, il est intéressant d'en savoir un peu plus car cela aide à comprendre certains évènements météorologiques. À mon avis, cela va contribuer à la formation de bons systèmes côtiers sur le territoire américain cet hiver. Bonne lecture.
Définition : http://fr.wikipedia....rg/wiki/El_Niño
Rapport de la NOAA : http://www.cpc.ncep....s-fcsts-web.pdf
Ci-dessous, un condensé d'un article d'Henry Margusity d'Accuweather. Il parle de La Nina dans le 3e paragraphe :
Thursday, January 08, 2009 3:34 PM
Snow Map and Long Range
CLIPPER STREAKS SOUTHEAST WITH A BAND OF MODERATE TO HEAVY SNOW... BITTER COLD NEXT WEEK WITH MORE SNOW...
I like forecasting clippers because they behave in regards to the snow areas. You still get some surprises with respect to the snowfall, but for the most part, things work out. Now, I have gone with a slightly southern storm track which means the heaviest snows will ride along I-80. That area will see 3-6 inches in general with up to 8 inches in spots across PA into southern New England. The cut off between snow and rain will be rather dramatic. For example, the northern suburbs of Baltimore may have 1-3 inches of snow while south of Baltimore, it could be raining. It's that type of cutoff between rain and snow that will occur from the Midwest all the way to the Delmarva.
Next week, things get quite interesting depending on what computer model you believe or who you believe. Right now the models are going with a series of clippers coming through but some models suggest a coastal storm develops. My concern is the extent of the cold air. You ever heard of the old saying, "it's too cold to snow." What that saying means, if you are deep in the cold air mass under a big high, you're not going to get snow. So next week when the huge high comes down and overwhelms much of the country east of the Rockies, a lot of places will be just too cold to snow and all the storminess will be shoved into the Gulf of Mexico and Atlantic.
On another note, I did find it interesting that NOAA has declared an La Nina is active. Given what I have seen so far this winter, the La Nina was probably around through fall and into December. It helps to explain why the Southeast has been so warm and why the storm track has been into the Great Lakes. Check out the image below and you tell me if that has not been the typical La Nina patter in December.
Modifié par uranium, 08 janvier 2009 - 19:36.