Alex Headed Toward Mexico - FLHurricane.com

One of the most important tools in a weather forecaster's arsenal is the 500 millibar (18,000 feet) Upper Air Analysis with Temperatures, Wind Direction & Speed, Heights in decameters, decamter difference from previous chart (12 hours ago) and dew point depression. I'll try and post the chart here; however if unsuccessful follow this link and print the chart yourself - http://weather.noaa.gov/pub/fax/QHTA11.TIF Replace "11" with "17" and that is the 700 millibar chart (10,000 feet).

A closer re-analysis of the chart reveals the longwave trough axis extending from the Hudson Bay southward through Wisconsin/Michigan through Iowa/Illinois through Missouri, Oklahoma/Arkansas possibly cutting off over Oklahoma/Texas and continuing as a trough through Central Texas. An inverted trough possibly cutoff extending south and southeast is Alex's circulation being reflected at 500 millibars. The entire area from the South Central US extending eastward to Alabama and Western Florida had 10 decameter height falls to the longwave troughs east and 10 to 20 decameters to the west of the longwave axis...this is indicative of a progressive (moving) east. Greatest height falls are north and east over the North Central and Northeast US as expected this time of year. For those of choose to print this chart, I analyzed the 585 and 587 heights and this will reveal the trough over Texas. I also re-analyzed the 588 height and drew it through Slideall/New Orleans, LA depicting the Bermuda ridge axis.

So what does this all mean you ask....it explains Alex's northward movement which is being steered by the longwave trough's current location.

Alex's intensity is reflected by the UW-CIMMS wind shear analysis. Alex is experiencing 15 knots of NW shear and will likely continue to experience this until the trough goes by and lifts out to the Northeast.

As of 1930Z this is the worse I've seen Alex on satellite and closer examination reveals Alex is moving N to NNW. There is some evidence on water vapor of that Alex is not vertically straight up but tilted slightly.

What troubles me is the position of the Mid-Continental and Bermuda ridges in a few days and an area of weakness; a COL (the intersection of two ridges and/or two troughs and/or all four) and today that's TX/LA border.

Those who are speculating in about 4 days the low off West FL is a piece of the trough that becomes cutoff. If it persists, it may bear watching but it's not related to Alex.

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Sincerely,

Bill Berry

"Survived Trigonometry and Calculus I"

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