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WTPZ44 KNHC 280853
TCDEP4

HURRICANE ULIKA DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192016
200 AM PDT WED SEP 28 2016

Ulika has continued to improve in organization, and recent microwave data have shown that the cyclone has maintained a well-defined eye in the 89-GHz channel during the past few hours. Hints of an eye have also been observed in shortwave infrared imagery, embedded within a compact central dense overcast. Subjective satellite intensity estimates have risen to T4.0/65 kt from TAFB and T3.0/55 kt from SAB, and the objective ADT from UW-CIMSS is even higher around 75 kt. A couple of CIMSS AMSU intensity estimates also provided values of 60-65 kt several hours ago. Based on these data, Ulika is upgraded to a hurricane with 65-kt winds, and this could be conservative.

Ulika has rapidly intensified during the past 24 hours, which in hindsight was probably helped by the cyclone's small wind field and radius of maximum winds. Vertical shear is expected to remain low for another 12 hours or so, which could allow Ulika to intensify some more in the short term. By 24 hours, however, southwesterly to westerly vertical shear is forecast to increase markedly, exceeding 30 kt in a couple of days. Given Ulika's small size, the cyclone will be particularly sensitive to the increase in shear, and its intensity is likely to decrease quickly. Ulika is expected to become a remnant low by day 4 and then dissipate southeast of the Hawaiian Islands by day 5. The NHC intensity forecast is very close to the intensity consensus for the entire forecast period, and is higher than the previous forecast during the first 36 hours to account for Ulika's recent intensification trend.

A mid- to upper-level low northwest of Ulika is steering the hurricane north-northeastward, or 030/6 kt. Ulika is expected to turn northward and northwestward around this feature during the next couple of days. After it becomes a weaker system, it should then come under greater influence from the low-level trades, turning west-northwestward and westward on days 3 and 4. With the exception of the GFDL, which is well north of the rest of the guidance suite, all of the track models are tightly clustered during the forecast period. The NHC track forecast is therefore close to the various consensus aids and not too different from the previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 13.9N 139.0W 65 KT 75 MPH 12H 28/1800Z 14.7N 138.9W 70 KT 80 MPH 24H 29/0600Z 15.6N 139.1W 65 KT 75 MPH 36H 29/1800Z 16.4N 139.6W 55 KT 65 MPH 48H 30/0600Z 17.0N 140.6W 45 KT 50 MPH 72H 01/0600Z 17.7N 143.3W 35 KT 40 MPH 96H 02/0600Z 17.7N 147.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 03/0600Z...DISSIPATED

$$ Forecaster Berg

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