Hurricane Chris Discussion Number 16
Wiki-Hurricanes Forecast Center
11:00 PM EDT Wed Jul 11 2018
Chris is beginning to make its steps toward becoming an extratropical cyclone. The eye has collapsed, and dry air is wrapping into the southern semicircle of the hurricane. Satellite intensity estimates at 0z were T4.0/65kt from both TAFB and SAB, and the final T-number from UW CIMSS ADT has decreased to T4.8/84.8kt. A simple blend of these values yields 70kt; however, given that Chris is still over marginally warm waters and its degradation in appearance is fairly new, the initial intensity has been set at 75kt instead.
The amount of time left for Chris to remain as a tropical entity is rapidly closing. The storm is beginning to cross the sharp gradient of the Gulf Stream and should enter ocean temperatures cooler than 12C within 18 hours. Increased interaction between the storm and the upper-level trough directing it northeast should increase southwesterly wind shear to over 25kt by that time as well. Finally, mid-level relative humidity values are forecast to fall below 50 percent; in the absence of an inner core and in the presence of strong wind shear, this should prove harmful to Chris. Extratropical transition is now expected around 18 hours from now, although this process could occur a few hours earlier given how cold the waters of the North Atlantic are.
On its current trajectory, Chris is expected to just southeast of Newfoundland in about 24 hours, delivering tropical storm-force winds and heavy rainfall, in addition to rough surf and high rip currents offshore. Chris should continue into the far North Atlantic thereafter, bending more eastward on the southern periphery of a broad mid-latitude low to the east of Greenland.
FORECAST POSITIONS AND MAX WINDS
INIT 12/0300Z 75 KT 85 MPH
12H 12/1200Z 65 KT 75 MPH
24H 13/0000Z 55 KT 65 MPH...POST-TROP/EXTRATROP
36H 13/1200Z 45 KT 50 MPH...POST-TROP/EXTRATROP
48H 14/0000Z 35 KT 40 MPH...POST-TROP/EXTRATROP