Tuesday, October 23, 2012

Sandy will she come and visit the Northeast?



I thought I would post a very quick update on Sandy.


Sandy:


Here is the latest Euro model run.


 17106_3576024169309_1032298207_n I think we can agree this looks very ominous. But it is only one model. We have 6 days where lots of things can change. The weather models have had some trouble handling tropical systems this year. Also, no storm that was once a hurricane has made a Northeast landfall after September, going all the way back to 1900.







The track forecast from the National Hurricane Center has not changed. Winds are 50mph, central pressure is down to 993mb, she is moving north northwest at 8 mph. The tropical storm wind field extends 90 miles.

 Here  is a little on Sandy. I think it is fairly safe to say most of us have been thinking and talking about Sandy and what she might do.   While she is only moving at 8 mph now, she will pick-up speed has she moves north over the next few days. She will be moving into an area where there is little in the way of vertical shear and the Sea Surface Temperatures are over 80 degrees. So she should become a hurricane around Jamaica.

We're going to have a negatively tilted trough moving south during the later part of the work week. What this trough does will be critical to Sandy's track.

The European and Canadian models are very amplified and show Sandy interacting with an arctic air mass and pull the storm inland, phasing it and dragging down unseasonably cold air. The earlier GFS runs had Sandy farther east and out to sea. However, As of this writing, the 18z GFS run had a major shift westward. It remains to be seen if it will shift more to the west or trend back to the east. As for the QPF, we only have to look back at Wilma to know what can happen when tropical moisture rich air, meets cold arctic air.....Lots of heavy snow...... in-fact some of the models are showing QPF amounts of 6-10 inches of precipitation. The Euro and Canadian have a very tight < 950mb pressure gradient , throw in the highly supportive low level jet , cold 0C H85 Temperatures, and dropping surface temps. It doesn't take much imagination to see snow in parts of Pennsylvania, New York, and New England. How much snow there is (if any) will depend on Sandy's track and intensity.  


 Severe weather:

We will also have severe weather Friday and Saturday in the Midwest. The Trough that is going to affect Sandy will also kickoff a bit of severe weather. An upper level low will be moving into the Plains. Cape Values will be marginal as will lapse rates. But, there will be a lot of shear and moisture in place. There will be enough directional shear that any thunderstorms that do develop will start to rotate. Right now, I think the major treats will be wind and hail......but there will be a few tornadoes thrown in as well. The upper level low will bring snow to the Great Lakes.

So what is the bottom line:

There isn't one really, there are still details to be ironed out. But the chances of a Northeast hit from Sandy, have gone up a notch.  I think the 00 GFS will come into alignment with the Euro. One thing I want to mention, the models are only a tool, there are many factors in play, only some of which I've mentioned here. We have a lot of time for things to change. One only has to look back at Isaac and New Orleans, the models will still making adjustments at land fall, so don't panic.   I will continue to watch the upper air patterns and see what the models do.

That’s about it…….I will post more blog updates as we get closer to the weekend.


Rebecca


























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