Friday, October 26, 2012

Sandy and Arkansas

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Sandy will not be as nice as the character in Grease.  Am I showing my age? You know I keep this weather blog all about Arkansas weather, but I'm going to take a detour to that approach for this post.  Although, I will be showing you how Sandy will impact our weather so that detour will be a very minor one.

This tropical system will phase with a cold system diving out of Canada to form a massive low pressure area which will affect MILLIONS of people along the east coast.  High winds, heavy rain, heavy surf, and even HEAVY mountain SNOW will all be possible from whatever is left of Sandy next week.  As I have mentioned in previous facebook posts and here on the blog, Sandy will impact travel across the country due to the ripple effect through our nation's airports.  So if you're a traveler next week, especially across the eastern United States, it could turn out to be a nightmare.

There's talk about this being a once in a hundred year storm.  Hype?  Maybe and maybe not.  We just don't know yet.  Plus, some people's perspective only dates back to when they began remembering things as a kid.  You know the movie, "Perfect Storm."  This was a similar situation, but if I remember correctly, it was worse away from the coast.  We have seen very disruptive storms before such as the Blizzard of 1993.  That produced severe weather in Florida and a massive snow storm from Alabama to the northeastern United States.  The way that storm was produced is different, but it was devastating for millions of people.  So I'll leave it up to you to decide if this turns out to be a 100 year storm.  Regardless, as a meteorologist, it will be fascinating to watch.

Sandy will impact our weather here in Arkansas... to a degree.  Pun intended.  Our average high temperatures for the end of October into the beginning of November are in the upper 60s to near 70 degrees.  The flow of air around the storm, will keep readings a few degrees below average and with a northwesterly flow in place... mostly dry.

Check out the model maps below from the European model

This is valid 7PM Sunday.  Look at Sandy just off the coast of North Carolina and Virginia.  The solid black lines are isobars (lines of equal barometric pressure).  The gradient is very steep around the storm indicating very high winds circulating counterclockwise into the storm.  The area of high pressure located in southern Canada is producing a northerly wind flow across Arkansas at the surface.  The colored contours are temperatures at 850 mb (roughly 5000 feet).  This shows very cool air at that level diving south and getting ready to get caught up in Sandy's circulation.  This will eventually make Sandy more of a hybrid system and produce snows on the western side of the system in the mountains along the eastern United States.
24 hours later, Sandy is ashore causing big problems according to the Euro.  Notice the cold air at 5000' is getting wrapped up into the system.  We still have a northerly flow here.  It's dry and cool in the central United States including Arkansas.
By 7 PM Tuesday, it's still going and we're continuing to see dry and cool weather as a result of Sandy.  While still a strong storm, it has weakened a little here.
I wanted to show you the 500 mb pattern.  This upper level chart shows winds coming out of the north/northwest across Arkansas.  This is a flow which continues to bring cool and dry air as we remain on the west side of the upper level system which caught Sandy.  At times, small disturbances can come through and bring clouds, but precipitation is difficult to produce due to the dry air in place.

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