Tropical Storm Chris Discussion Number 5

Wiki-Hurricanes Forecast Center

5:00 PM EDT Sun Jul 8 2018

Chris continues to become better organized this afternoon. Satellite imagery shows that while some dislocation of the low- and mid-level circulations exist, the overall cloud pattern has become substantially better organized over the past 12 hours, with hints of a mid-level eye developing. An Air Force reconnaissance aircraft investigating the storm found peak flight-level winds of 50kt, which would support an initial intensity of 40kt; there was a peak believable SFMR value of 48kt, which would support an initial intensity of 50kt. Therefore, I have taken the middle of the two for a starting strength of 45kt.

There has been little change to the track forecast. Chris is located within a region of collapsed steering currents, with a developing ridge over the Northeast United States and an upper-level low to the northeast of the tropical cyclone. Little motion is expected for the next 48 hours. Thereafter, a broader trough digging south from Canada should erode the aforementioned ridge and act to provide an outlet to the northeast for Chris. Models are in generally good agreement for this evolution. A northeast trajectory in the medium range should send Chris, as a post-tropical cyclone by this point, toward Newfoundland, where adverse conditions are possible.

The environment is currently marginally favorable, with a nearby front imparting moderate wind shear on Chris. However, this front is expected to dissipate tomorrow and give way to expansive anticyclonic flow aloft. Ocean temperatures are very warm, and this warm water extends down with depth as is characteristic of the Gulf Stream. Continental dry air will lurk nearby, but in the absence of strong upper-level winds, any intrusions should be temporary. The SHIPS and LGEM continue to indicate a Category 2 and Category 1 hurricane, respectively. However, global models, particularly the ECMWF, are more bullish and suggest the potential for a major hurricane. Given the environment and its current state of organization, the intensity forecast has been raised. Weakening is expected after 72 hours as Chris moves over frigid waters and interacts with the upper-level trough.


INIT 08/2100Z 45 KT 50 MPH

12H 09/0600Z 55 KT 65 MPH

24H 09/1800Z 65 KT 75 MPH

36H 10/0600Z 75 KT 85 MPH

48H 10/1800Z 90 KT 105 MPH

72H 11/1800Z 85 KT 100 MPH

96H 12/1800Z 60 KT 70 MPH

120H 13/1800Z 45 KT 50 MPH...POST-TROP/EXTRATROP

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