Statement as of 11:00 PM EDT on August 18, 2007the inner core of Dean appears to be undergoing some changes. Radar
imagery onboard the Air Force reconnaissance aircraft depicts
concentric eyewalls at radii of about 10 and 20 N mi...with the
outer eyewall recently becoming a little better defined.
Flight-level winds have also revealed double maxima. Wind data at
flight level...from the SFMR...and from dropsondes directly support
an intensity of no more than about 115 kt. The central
pressure...however...has been gradually dropping and was most
recently measured at 918 mb. Assuming that the maximum wind has
not been sampled...the advisory intensity is set to 125 kt...but
this could be a bit on the high side. The aircraft will continue
to investigate Dean for a few more hours to see if the winds come
back up.
Dean wobbled westward earlier this evening...but the longer-term
motion toward 280 degrees at about 15 kt seems to have resumed. As
the models have been forecasting...the mid- to upper-level low that
was east of Florida a couple of days ago is now over the eastern
Gulf of Mexico and headed quickly westward. That low is forecast to
be replaced by a large and strong ridge over the southeastern
United States during the next couple of days...which should
reinforce a general west-northwestward motion of Dean...through the
northwestern Caribbean...over some portion of the Yucatan
Peninsula...and into the southern Gulf of Mexico. The models have
in general shifted slightly southward...including the GFDL which is
no longer the northern outlier. The guidance is now in very good
agreement on the track throughout the entire five-day forecast
period...so confidence in the track forecast is increasing. The
official track forecast has been adjusted a tad to the south and is
very near the dynamical model consensus.
The short-term intensity forecast is a bit uncertain given the
double eyewall structure...but the central pressure is quite low and
the inner core could quickly reorganize at any time...so any dip in
the intensity will probably be short-lived. Throughout its stay in
the Caribbean Sea during the next 48 hours or so...atmospheric and
oceanic conditions remain supportive of a category four or five
intensity as suggested by all of the objective guidance. Since the
new track forecast results in a longer stay over the Yucatan
Peninsula...the official intensity forecast has been lowered
slightly over the southwestern Gulf of Mexico...but still indicates
a major hurricane at final landfall.
Forecast positions and Max winds
initial 19/0300z 16.2n 71.7w 125 kt
12hr VT 19/1200z 16.8n 74.3w 130 kt
24hr VT 20/0000z 17.6n 77.8w 130 kt
36hr VT 20/1200z 18.4n 81.4w 135 kt
48hr VT 21/0000z 19.3n 85.1w 140 kt
72hr VT 22/0000z 21.0n 92.0w 85 kt
96hr VT 23/0000z 23.0n 98.0w 100 kt...inland
120hr VT 24/0000z 24.0n 101.0w 30 kt...inland
$$
forecaster Knabb
From:
HERE
