typhoon_tip
(Meteorologist)
Sat Jun 26 2010 06:40 PM
Re: TD1 Upgraded to TS Alex as of 5 am ET

Indeed, obviously the stakes are very high for the coastal communities along the northern and eastern Gulf.

The destiny of Alex will depend upon the accurate handling of a large scale pattern change across North America. This pattern change is well agreed upon by the panoply of Global numerical guidance, and for the time being is encouraging.

Previously, ...the guidance' that were grabbing Alex and pulling the cyclone N through the Yucatán Strait were lowering heights farther south in latitude in association with a trough getting ready to incur into the Ohio Valley and East Coast. This was causing a weakness in the native heights throughout the Gulf - ultimately leading to an earlier polarward turn for Alex. Since, however, guidance is now restricting the lowering height anomalies primarily into the NE conus region, and the resulting loss of weakness over the Gulf is tremendously good news should it prevail (which it appears will be the case). That should keep the general steering field angled left and away from the ecological disaster unfolding in the NE Gulf of Mexico and adjacent areas.

As for populations along the Mexico and southern Texas coasts, these areas look for the time being to be the higher probability for impact.

As usual, the question becomes 'what is left of Alex upon traversing the Yucatan Peninsula?' A lot of that will come down to how strong Alex becomes prior to impact with land. A system with more integrated storm energy will quite naturally be more resistant at first to the hostility of land. One thing also to keep in mind is that the Yucatan Pen. is a very flat, humid land mass. Diurnal convection over the region keeps soil moisture content very high much of the time. While this could never serve physically to strengthen a TC, it may mitigate the rate of decay when comparing other land falling TCs. An example of this was across southern Florida when Katrina traversed; Katrina was strengthening to Cat 1 status upon entering the Atlantic-side Coast, and emerged with no detrimental effects for having spent time over land.

Other than the Yucatan region there does not appear to be any parameters that would interfere with intensification, and this appears to be true in the modeling for the surrounding region out through day 5. In fact, if it were not for the proximity to land one might be concerned that a Rapid Intensification cycle could take place. The probability for that is not 0 prior to land falling on the Yucatan, however, with landfall expected now ahead of schedule, the probability is approaching 0. NHC has noted that the inner core is less organized earlier this morning, but recent IR images of Alex show that a CDO feature may in fact be in the process of developing. The most recent advisory issued at 1pm is holding wind speed at 45mph, with BP of 1003mb. RECON is inbound so we shall soon see what they measure.


John.



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