000
WTNT43 KNHC 090843
TCDAT3

Tropical Storm Chris Discussion Number  11
NWS National Hurricane Center Miami FL       AL032018
500 AM EDT Mon Jul 09 2018

After the expansion of deep convection during the evening it
appears that some drier air has been entrained into the
circulation which has caused a general warming of the cloud tops
and some erosion of the deep convection overnight. However, the
banding remains well organized and the overall structure of the
cyclone has not changed appreciably.  An Air Force Reserve
reconnaissance aircraft investigating the system has found that the
minimum pressure has dropped to 999 mb, but the flight-level and
SFMR winds still support an initial intensity of 50 kt.

Recent aircraft and satellite fixes indicate that Chris is
drifting southward.  Steering currents are expected to remain
quite weak during the next 36 hours as Chris is situated between a
couple of mid-level highs and a mid- to upper-level trough to its
northeast.  By late Tuesday, a deep-layer trough moving across the
Great Lakes region should begin to lift Chris out toward the
northeast.  The cyclone is predicted to accelerate northeastward
during the remainder of the forecast period as it gets caught in
strong southwesterly flow ahead of the aforementioned trough.  The
track models are in good agreement on this general scenario but
there are some differences in how fast Chris accelerates over the
western Atlantic.  The new NHC track forecast has been shifted
slightly northwestward to be in better agreement with the latest
guidance, and it remains near the model consensus to account for
the forward speed differences among the various track models.

The cyclone should be able to mix out the dry air that it entrained
while it is located over warm water and in light to moderate
vertical wind shear conditions.  This should allow strengthening
during the next couple of days, but there could be some upwelling
beneath the slow moving cyclone which could temper the rate of
intensification.  The new NHC track forecast shows a slightly slower
rate of deepening during the next 24 to 36 h, but still forecasts
Chris to become a hurricane later today or tonight, and reach about
the same peak intensity as shown in the previous advisory.  The
hurricane should become extratropical by 96 h, and the global models
indicate that steady weakening will occur after that time.


FORECAST POSITIONS AND MAX WINDS

INIT  09/0900Z 32.4N  74.6W   50 KT  60 MPH
 12H  09/1800Z 32.4N  74.6W   55 KT  65 MPH
 24H  10/0600Z 32.5N  74.7W   65 KT  75 MPH
 36H  10/1800Z 33.0N  73.9W   70 KT  80 MPH
 48H  11/0600Z 34.2N  72.2W   80 KT  90 MPH
 72H  12/0600Z 39.0N  66.4W   80 KT  90 MPH
 96H  13/0600Z 45.5N  59.3W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  14/0600Z 49.5N  49.5W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown