[texbirds-freelists] Re: [texbirds] NEXRAD radar observations of migrating birds in the western Gulf coast region, 4/9

Just to chime in on the anomalous weather pattern. By Friday and into early
next week it looks as though the pattern will finally be changing and a
return to the more typical strong southerly winds of spring is expected.
This will be a result of the upper ridge currently over Texas and the
western Gulf shifting eastward ahead of a large storm system digging into
the western United States.

Sustained winds at the surface of 15 to 25 knots or higher out of the SE
will be common from the Bay of Campeche to the northern Gulf coast by
Friday and Saturday into next week. Good tail wind for the birds but not so
great for birders in the field.

The weather system out west could produce some pretty significant weather
for Texas next week. I won't make any promises on cold fronts just yet
given how this year has gone but a rough estimate if things stay on track
would be to have a cold front at the coast by late Tuesday or Wednesday.

John Tharp
Houston, TX

On Mon, Apr 9, 2012 at 1:14 PM, John Arvin <jarvin@xxxxxxxx> wrote:

> The consistent run of extremely low upper air velocities is amazing and
> unprecedented in my experience of attempting to analyze NEXRAD imagery over
> the past 7 spring seasons. Two (that's 2) kt. at Brownsville sounds like a
> rare day ever for late August and unheard of in what is still the first
> half of spring migration. All stations were single digits except a 10
> kt.at
> New Orleans at E to N. Even Merida, Yucatan, was in single digits. There's
> not much incentive for staging migrants to launch a trans-Gulf flight under
> these conditions as it is a long flight if there are no tail winds to add
> to the still-air flight speed of passerines. Some (but not many) have been
> doing so, however, and successfully. The familiar conveyor belt of stiff S
> to SE winds that carries the trans-Gulf migrants each spring appears to
> have broken down. Nevertheless "cyber-birding" the listserves shows that
> the usual species are arriving at more-or-less the usual dates (some
> notably early) if not in great numbers. You would expect that such a
> departure from normal spring weather patterns would produce some notable
> phenomenon and it has - pleasant spring birding conditions.
>
>
> Checking the stations at 13:00 shows some raptor-like flocks in northern
> Willacy and central Kenedy Counties in South Texas and a sprinkling of
> migrants offshore from the Corpus Christi area. I will check later on to
> see if things pick up and update if they do.
>
> John C. Arvin
> Research Associate
> Gulf Coast Bird Observatory
> 103 West Hwy 332
> Lake Jackson, TX 77566
> jarvin@xxxxxxxx
> www.gcbo.org
>
> Austin, Texas
>
>
> TEXBIRDS help file and Texas birding links at:
> http://moonmountaingroup.com/texbirds
>
>

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