ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM
Tropical Storm Karina Discussion Number 3
NWS National Hurricane Center Miami FL EP162020
900 AM MDT Sun Sep 13 2020
Karina's center is a little bit closer to the deep convection this
morning, resulting in intensity estimates increasing slightly.
Based on Dvorak estimates of T3.0/45 kt and T2.5/35 kt from TAFB
and SAB, respectively, and an overnight SATCON estimate of 42 kt,
Karina's initial intensity is assumed to be 40 kt. The moderate
northeasterly shear currently affecting the cyclone is not expected
to change appreciably during the next few days. However, Karina
will remain over ocean waters warmer than 26 degrees Celsius for
the next 48 hours, which should allow for a gradual intensification
trend during that period. The shear is forecast to lighten up in
3-4 days, but by then Karina will be over colder waters and in a
drier, more stable environment, which should induce weakening.
Karina is likely to lose all of its deep convection and become a
remnant low by the end of the forecast period. The NHC intensity
forecast is generally close to the HCCA aid and the IVCN intensity
consensus and shows weakening starting a little sooner than before.
Karina is moving toward the west-northwest (300/9 kt), south of a
mid-level ridge axis which extends from northwestern Mexico
southwestward over the Pacific. This ridge should keep Karina on
this general heading with a very gradually decreasing forward speed
through day 4. Once the cyclone weakens to a remnant low, it is
expected to turn westward, steered by lower-level trade winds. No
significant changes in the track forecast were required compared to
the previous prediction, and the official forecast lies generally
close to the multi-model consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 13/1500Z 17.6N 114.7W 40 KT 45 MPH
12H 14/0000Z 18.3N 115.8W 45 KT 50 MPH
24H 14/1200Z 19.0N 117.4W 45 KT 50 MPH
36H 15/0000Z 19.7N 119.0W 50 KT 60 MPH
48H 15/1200Z 20.2N 120.4W 55 KT 65 MPH
60H 16/0000Z 20.9N 121.6W 50 KT 60 MPH
72H 16/1200Z 21.7N 122.8W 50 KT 60 MPH
96H 17/1200Z 22.6N 125.2W 35 KT 40 MPH
120H 18/1200Z 22.8N 127.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
Forecaster Berg
NNNN