Important Hurricane Sandy Update! 10/27/12

Sandy was “only” classified as a Category 1 hurricane Saturday morning with maximum sustained winds of 75 mph and gusts to 90 mph. Don’t let that fool you into letting your guard down. Sandy’s central pressure is very low (958mb), which means she will hold her strength extremely well while transitioning to a sprawling Über-Hybrid Nor’easter. Call it Frankenstorm if you wish……

The most important trend of the short range models is the forecast acceleration of Sandy on Monday. Latest NAM is showing that Sandy should make landfall over New Jersey before Monday evening. That is nearly 12 hours sooner than previously expected!

Inland Sandy
Effects of Sandy’s rapid acceleration will include:

1) Increasing the high wind potential for the Adirondacks:

Atmospheric pressure gradient is the main force that drives wind. The rapid movement of Sandy on Monday will compress the pressure gradient ahead of her prior to landfall, which further increases wind speeds. Locations that are highly vulnerable to easterly winds may experience wind gusts over 60mph Monday afternoon and into the first half of Monday night!

2) Cause freakish local variations in rainfall totals:

Strong easterly winds will favor heavier rain over the eastern Adirondacks and lighter rains over the western Adirondacks. The sheer strength of Sandy will cause further local variations due to small scale precipitation banding that the models won’t accurately pick up:

Sandy precipitation

Precipitation (inches) through 8PM Tuesday

The chart includes precipitation through 8PM Tuesday and additional rain will continue through Wednesday as Sandy pinwheels over Pennsylvania. However, widespread flooding should NOT be expected for the Adirondacks, with rainfall potential capped at 1-3 inches in most spots for the entire event (Monday thru Wednesday).

Comparing 2012 Sandy to 2011 Irene:

In terms of heavy rain, Irene was much worse than Sandy will be. Irene tracked up the Connecticut Valley, which placed much of the Adirondacks in the sweet zone for heavy rainfall (3-6+ inches) to the left of the storm’s track. We will be to the right of Sandy’s track as she tracks through New Jersey into Pennsylvania. Dry air entrainment to the right of Sandy’s path will cut down on rainfall for the Adirondacks.

On the other hand, I think that Sandy may generate stronger wind than Irene did. With tropical systems, the highest winds usually occur to the right of the storm’s track, which will be the case for us with Sandy.

Either way you slice it, Sandy will likely cause widespread and significant tree blow down throughout the Adirondacks on Monday. Make sure that your generator and chainsaw work before she gets here! You have all weekend to prepare….

Comments welcomed!

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