Eastern Pacific Basin Tropical Cyclones

Tropical Storm Orlene Forecast Discussion


000
WTPZ41 KNHC 292042
TCDEP1

Tropical Storm Orlene Discussion Number   4
NWS National Hurricane Center Miami FL       EP162022
300 PM MDT Thu Sep 29 2022

Satellite imagery shows that Orlene has the same convective features 
that it had earlier today, with a small central dense overcast and 
an outer convective band that wraps about three-quarters of the way 
around the central feature. However, both the central and outer 
convection have become more ragged, and some parts of the outer band 
currently look like an arc cloud.  This structure suggests the 
possibility of some dry air near the cyclone despite an overall 
moist environment. A recent scatterometer overpass indicated maximum 
winds near 40 kt, and based on this data, the initial intensity 
remains 40 kt.  This is also close to the 35 and 45 kt satellite 
intensity estimates from SAB and TAFB, respectively. 

The initial motion is west-northwestward or 295/7 kt.  Orlene is 
being steered by a mid-level ridge over Mexico, with the cyclone 
forecast to reach the western end of the ridge during the next 12-24 
h.  This should lead to a turn toward the northwest and north during 
this time-frame.  After 24 h, Orlene should move generally 
northward to north-northeastward in the flow between the ridge and a 
mid- to upper-level trough currently developing over northwestern 
Mexico and the northern Baja California peninsula. The UKMET and 
ECMWF now forecast a stronger Orlene, and as a result they have 
joined the other models in forecasting a northward motion.  However, 
those models have a slower forward speed than the GFS. Overall, the 
guidance envelope has shifted eastward since the last advisory, and 
the new forecast track is also adjusted eastward after 24 h.  The 
new track lies near or to the west of the various consensus models, 
and it calls for the center to move into Mexico between 96-120 h.

Orlene is forecast to be within an environment of moist air and low 
vertical wind shear for the 72 h or so. The guidance is now in good 
agreement on at least steady intensification during this time, and 
the various rapid intensification indices in the SHIPS model 
suggest rapid intensification is possible during the next 24-36 h. 
After 72 h, Orlene is likely to encounter increasing shear and a 
drier air mass, which should cause weakening.  However, the GFS and 
HMON models continue to forecast the cyclone to make landfall as a 
hurricane, and the new intensity forecast again follows that 
scenario.  It should be noted that Orlene is very small.  This could 
allow the cyclone to more easily intensify when the environment is 
favorable, but it could also make it more vulnerable to subtly less 
favorable environmental conditions.


FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 15.4N 106.5W   40 KT  45 MPH
 12H  30/0600Z 16.0N 107.5W   50 KT  60 MPH
 24H  30/1800Z 16.9N 108.1W   60 KT  70 MPH
 36H  01/0600Z 17.6N 108.3W   70 KT  80 MPH
 48H  01/1800Z 18.6N 108.2W   80 KT  90 MPH
 60H  02/0600Z 19.6N 108.0W   85 KT 100 MPH
 72H  02/1800Z 20.8N 107.8W   80 KT  90 MPH
 96H  03/1800Z 23.5N 107.0W   65 KT  75 MPH
120H  04/1800Z 26.1N 106.5W   25 KT  30 MPH...INLAND

$$
Forecaster Beven



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