HURRICANE BERTHA DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032014
1100 AM EDT MON AUG 04 2014
In spite of its unimpressive appearance on satellite imagery, with
scant evidence of banding features and relatively disorganized deep
convection, aerial reconnaissance data indicate that Bertha has
intensified into a hurricane. Flight-level, dropsonde, and SFMR
winds from Air Force and NOAA Hurricane Hunter planes support an
intensity of 70 kt for this advisory. Bertha does have well-defined
anticyclonic upper-level outflow over the eastern and southern
portions of the circulation. Recent infrared imagery shows warming
cloud tops, so the intensity is probably leveling off. Dynamical
guidance predicts a very large increase in shear beginning in 24-36
hours, and a weakening trend is forecast to begin around that time.
In about 72 hours, the global models show the cyclone interacting
with a baroclinic zone in the vicinity of Newfoundland, so the NHC
forecast shows Bertha becoming extratropical by that time.
Center fixes from the Hurricane Hunter aircraft indicate that the
motion is now 360/15 kt. The track forecast remains relatively
straightforward. Over the next couple of days, Bertha should turn
toward the northeast and accelerate in the flow between a
mid-tropospheric anticyclone over the southwestern Atlantic and a
broad trough moving off the United States east coast. Later in the
forecast period, the cyclone should continue moving quickly to the
northeast or east-northeast within the mid-latitude westerlies.
The official forecast track is not much different from the previous
one, and close to the dynamical model consensus.