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Hurricane Lee--Glorified Nor'Easter or Legit Tropical? Near Miss or Direct Hit?


WxWatcher007
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1 hour ago, Layman said:

Non-meteorologist here (1st post as well...):  is there a formula or other standard to define or predict the reduction in wind speed upon encountering land?

For example, if there are sustained 60mph winds at the coastline, are there high-confidence ways to predict/forecast winds 1 mile, 2 miles, 5 and 10 miles inland?

Where I'm physically situated, and from comments I've seen over the years from others, it seems that forecast gusts rarely reach the speeds predicted in the weather apps.  

Good question with no simple answer.  A few things in play... the friction increase is the most determental item to maintaining the speed you see over the open ocean... also factors such as terrain features, elevation, wide open areas v urban areas, as well as the direction of the wind all play into how much wind speeds will decrease.  Another very important factor is whether or not the low-level atmosphere is stable or not... many times the atmosphere near the coast is more unstable (warmer at the surface through the lower levels of the atmosphere) and this allows the very strong winds often found between 2 and 4 thousand feet to mix down to the surface.  Many times the inland temperature profile is more stable, warms as you go higher into the 2 to 4 thousand foot level.  This prevents the strong winds aloft from mixing down to the surface across inland area. Although high elevations can have an easier time seeing strong winds. The more unstable the lower atmosphere is the easier it is to get the stronger winds to the surface. Most of the time, if I don't think the inland air mass will be unstable (able to mix) I cut modeled land wind gust by 5 to 10% .

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6 minutes ago, FXWX said:

Good question with no simple answer.  A few things in play... the friction increase is the most determental item to maintaining the speed you see over the open ocean... also factors such as terrain features, elevation, wide open areas v urban areas, as well as the direction of the wind all play into how much wind speeds will decrease.  Another very important factor is whether or not the low-level atmosphere is stable or not... many times the atmosphere near the coast is more unstable (warmer at the surface through the lower levels of the atmosphere) and this allows the very strong winds often found between 2 and 4 thousand feet to mix down to the surface.  Many times the inland temperature profile is more stable, warms as you go higher into the 2 to 4 thousand foot level.  This prevents the strong winds aloft from mixing down to the surface across inland area. Although high elevations can have an easier time seeing strong winds. The more unstable the lower atmosphere is the easier it is to get the stronger winds to the surface. Most of the time, if I don't think the inland air mass will be unstable (able to mix) I cut modeled land wind gust by 5 to 10% .

This is so good. Many of these factors are in my head whenever I’m chasing. 

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I am surprised that the National Weather Service has not issued a wind advisory for Inland areas. Gray Maine hasn't done it either. It's not like anything is really going to change with the track or intensity of the storm it's not already known so why the delay unless they don't even think it will meet that criteria?

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1 hour ago, FXWX said:

Good question with no simple answer.  A few things in play... the friction increase is the most determental item to maintaining the speed you see over the open ocean... also factors such as terrain features, elevation, wide open areas v urban areas, as well as the direction of the wind all play into how much wind speeds will decrease.  Another very important factor is whether or not the low-level atmosphere is stable or not... many times the atmosphere near the coast is more unstable (warmer at the surface through the lower levels of the atmosphere) and this allows the very strong winds often found between 2 and 4 thousand feet to mix down to the surface.  Many times the inland temperature profile is more stable, warms as you go higher into the 2 to 4 thousand foot level.  This prevents the strong winds aloft from mixing down to the surface across inland area. Although high elevations can have an easier time seeing strong winds. The more unstable the lower atmosphere is the easier it is to get the stronger winds to the surface. Most of the time, if I don't think the inland air mass will be unstable (able to mix) I cut modeled land wind gust by 5 to 10% .

Thank you for the detailed reply.  It'll be interesting to see how the winds from this one ultimately play out compared to forecasts.

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15 minutes ago, Chrisrotary12 said:

The first post in the tropical thread regarding a potential Lee was on September 1. What a waste of 15 days. While many knew it would pass east and not landfall, the storm itself was only really worth watching for about 12 hrs.

But most did, I'm sure HHH had more potential........:lol:

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