|Tropical Storm Erick||Winds: 50 kt|
|Pressure: 1000 mbar|
|Advisory 7 / 8:00 PM PDT Sunday, July 28, 2019|
Erick has become substantially better organized this evening, with the formation of a central dense overcast, as well as the expansion of spiral banding and upper-level outflow. A microwave pass shortly after 0z showed that Erick was in the initial stages of developing a sturdy inner core. Satellite intensity estimates range from T3.4/53kt from UW-CIMSS ADT to T3.5/55kt from both SAB and TAFB. These values would support an initial intensity of 55kt. However, I have elected to go slightly lower, 50kt, given that maximum winds as confirmed by ASCAT have tended to lag estimates thus far.
Erick has deviated from expectations this evening, moving a little south of west. A general westward motion is expected for the next 24 hours or so thanks to broad and strong mid-level ridging to the storm's north. Between 24 and 96 hours, Erick should move more west-northwest thanks to a subtle weakness in the area of high pressure. By day 5, the shallow nature of the storm should allow it to be steered by the low-level easterly trade winds; a westward turn should occur as a result. On this trajectory, Erick is expected to pass comfortably south of Hawaii.
Upper-level winds are about as low as you will ever see for a tropical cyclone, with SHIPS analyzing wind shear of 4kt or less for the next 48 hours. Ocean temperatures should remain above 27C during that time, and in fact, throughout the entire forecast period. This is a shift from earlier predictions as a result of Erick's southward dip today; this was discussed as a possibility in last night's advisory. Since water temperatures are expected to remain warmer than first thought, mid-level relative humidity values too should fall at a slower pace than original projections. These shifts have resulted in an upward trend from SHIPS and LGEM, which join the GFS in predicting a Category 2 hurricane. The HWRF also predicts a ~95kt Category 2 hurricane. One fly in the ointment is that SHIPS rapid intensification indices have dramatically increased since earlier, with a nearly 8-in-10 chance for 25kt development over the next day, and even a 7-in-10 chance of a 45kt increase over the next 36 hours. I am still monitoring the potential influence of a convectively-suppressed kelvin wave, but the brunt of this wave has passed now, decreasing the possibility for adverse effects on Erick. Therefore, the intensity forecast has been dramatically increased in the short term and depicts an explicit peak intensity of 100kt in 48 hours, a little above guidance. Weakening is expected on days 3 through 5 because, although ocean temps and moisture values are depicted as higher than previous forecasts for this cycle, upper-level winds are expected to become hostile.
FORECAST MAX WINDS
INIT 29/0300Z 50 KT 60 MPH
12H 29/1200Z 60 KT 70 MPH
24H 30/0000Z 75 KT 85 MPH
36H 30/1200Z 90 KT 105 MPH
48H 31/0000Z 100 KT 115 MPH
72H 01/0000Z 90 KT 105 MPH
96H 02/0000Z 50 KT 60 MPH120H 03/0000Z 35 KT 40 MPH