Tropical Storm Kristy Discussion Number 6

Wiki-Hurricanes Forecast Center

8:00 AM PDT Wed Aug 8 2018

Kristy has continued to fire deep convection this morning, perhaps aided by the oceanic diurnal maximum. However, this deep convection is being driven by a mid-level center offset east of the center, and thus Kristy has adopted a fairly classic look of a sheared tropical cyclone with the low-level circulation embedded somewhat in the convection, but not under deep developing shower activity. Shortwave infrared and nighttime microphysics products show the displacement, and microwave all but removes any doubt, depicting a clear cut circulation delineated by low-level cloud lines hinging on the edge of deep convective activity. UW-CIMSS ADT has held out the lower end of satellite estimates at T2.3/33kt, while SAB and TAFB are higher with each estimating T3.0/45kt for a current intensity. SATCON offered a good blended compromise between low infrared and high microwave estimates with a 40 kt consensus, so I am going with this value for the current intensity.

Kristy is crawling slowly towards the west-northwest, but should be in the process of turning towards the northwest as it begins to feel the combined pull of both Hurricane John's expansive circulation and a small localized upper-level low positioned to John's southwest. Model solutions are now more in agreement in this turn, with EPS ensemble guidance now showing interaction, but diverge oncemore after about 72 hours; at this point, Kristy could either continue interacting with John and be pulled towards its circulation if it maintains some intensity, or it could be weak enough to thin out and move west with the dominant low-level easterlies. The intensity forecast is generally bleak for Kristy, with the storm's current structure unsupportive of intensity maintenance over the marginal sea surface temperatures it is expected to encounter over the next few days. Upper-level wind shear is expected to decrease with time, though this is not particularly of use if Kristy is not already an organized system independently driving its own environment like Hector in similar conditions in the Central Pacific. Most guidance shows some strengthening in the short-term before gradual weakening occurs. Degeneration to a remnant low is shown by day 5 as dry conditions take root, but the transition could occur sooner.


INIT 08/1500Z 40 KT 45 MPH

12H 09/0000Z 40 KT 50 MPH

24H 09/1200Z 45 KT 50 MPH

36H 10/0000Z 45 KT 45 MPH

48H 10/1200Z 45 KT 50 MPH

72H 11/0000Z 40 KT 50 MPH

96H 12/0000Z 35 KT 45 MPH

120H 13/0000Z 30 KT 35 MPH...POST-TROP/REMNT LOW

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