Statement as of 4:00 PM CDT on July 11, 2003
Claudette is quite disorganized this afternoon. The low-level
center has become elongated east-northeast to west-southwest...and
there are 3 or 4 cloud swirls/vorticity centers rotating around the
mean center. The strongest remaining convection is well east of
the center. Based on the 50-55 kt flight level winds reported
earlier by the reconnaissance aircraft and the degraded satellite
appearence...the initial intensity is reduced to 45 kt.
The initial motion is an uncertain 310/12. Water vapor imagery
shows an upper-level cyclonic shear axis west of Claudette...with a
mid/upper-level trough over the central and eastern United States
extending southwestward to near 32n92w. A large upper-level
anticyclone is centered near Grand Cayman island. Surface and
rawinsonde data indicates low-level ridging over the northern Gulf
of Mexico. Present indications are the trough will reach its
maximum southern extent near 85w or east of the longitude of
Claudette...and that the trough is unlikely to recurve the cyclone.
Most dynamic guidance responds to this pattern by moving Claudette
northwest for 24-48 hours...followed by a gradual westward turn.
The LBAR and the mm5 take the storm toward Louisiana...which looks
strange in light of the northerly 500 mb flow that all models
forecast in that area. The UKMET has also jumped further north...
but is inconsistent with its previous runs and is thus discounted
for the moment. The track forecast will be an update of the
previous package and down the middle of the westward model suite.
Claudette remains in significant southerly shear. This and the
current disorganization will likely prevent strengthening for
12-24 hours. After that...the intensity depends on how a large
upper-level anticyclone forecast by the dynamical models actually
develops. The NOGAPS is now the only model to develop the
anticyclone over Claudette. The UKMET...GFS...and Canadian develop
the anticyclone south of the forecast track... which would expose
the cyclone to some westerly shear. This looks like the most
likely scenario...and the intensity forecast calls for only slow
development in response. It should be noted that if Claudette
strengthens significantly during the first 24 hr...the storm could
move more toward the north due to the southerly upper-level flow.
The chances of this appear low at this time.
The NOAA Gulfstream IV jet is currently conducting a synoptic
surveillance mission...with the data to be used in the 00z models.