Hurricane John Discussion Number 14
9:00 PM MDT Wed Aug 8 2018
John has continued to degrade in presentation since the previous advisory, with an open eyewall on microwave imagery and no clear signs of an eye on infrared imagery. Satellite intensity estimates were T4.0/65kt from SAB and TAFB, with T4.5/77kt from UW-CIMSS ADT. The raw values from CIMSS are closer to the previous two agencies, and so the initial intensity is set to 65kt. While wind shear remains light around John, water temperatures have cooled below 26C and will only continue to fall. Mid-level relative humidity values should also decrease over the next few days; John's large circulation will only exacerbate dry air struggles. Therefore, the system should degenerate to a remnant low in about 72 hours, although it's possible this could occur sooner.
The track forecast remains pretty easy. John is moving northwest on the southwestern edge of a mid-level ridge. This motion should continue for the next 2 to 3 days. Thereafter, as John becomes a shallow area of low pressure, it should turn west under the influence of low-level flow before stalling out at the end of the period in a light steering regime.
MAXIMUM WINDS FORECAST
INIT 09/0300Z 65 KT 75 MPH
12H 09/1200Z 60 KT 70 MPH
24H 10/0000Z 50 KT 60 MPH
36H 10/1200Z 40 KT 45 MPH
48H 11/0000Z 35 KT 40 MPH
72H 12/0000Z 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 13/0000Z 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 14/0000Z 15 KT 20 MPH...POST-TROP/REMNT LOW