Eastern Pacific Basin Tropical Cyclones

Tropical Storm Madeline Forecast Discussion


245 
WTPZ44 KNHC 200849
TCDEP4

Tropical Storm Madeline Discussion Number  11
NWS National Hurricane Center Miami FL       EP142022
300 AM MDT Tue Sep 20 2022

Since the last advisory, Madeline's structure has gone downhill in a 
hurry. The convection that existed earlier today has largely sheared 
away to the west and dissipated, revealing a well-defined low-level 
swirl that is easy to find on nighttime proxy-vis GOES-17 satellite 
imagery. It appears the increase in easterly shear, in combination 
with the tropical cyclone crossing the 26 C sea-surface temperature 
(SST) isotherm, has led to this structural collapse. Subjective 
Dvorak T-numbers were falling as fast as the constraints would 
allow, but based on the rapid deterioration in the structure, in 
addition to some west edge scatterometer wind data indicating only 
29-31 kt winds just 50 n mi west-southwest of the center, the 
initial intensity is being reduced to 35 kt this advisory.

Madeline has nearly completed its turn to the west, with the motion 
now estimated at 280/7 kt. This motion should continue with an 
additional gentle bend leftward as the storm becomes increasingly 
shallow and steered by the low-level flow. The NHC track forecast is 
a touch south of the prior one, in good agreement with the 
multi-model consensus aids. 

Madeline's track overnight has put it over anomalously cold SSTs 
that are a leftover from Hurricane Kay that traversed this area more 
than a week ago. With the overnight evaporation of deep organized 
convection, the clock is now ticking on Madeline's remaining 
lifespan as a tropical cyclone. The latest NHC forecast now shows 
the cyclone becoming a post-tropical remnant low in just 24 hours. 
There is one caveat to this forecast. Along Madeline's track, SSTs 
do start to increase again in 36 hours, and simulated satellite 
imagery from both the GFS and ECMWF suggest some brief puffs of deep 
convection could occur in the day 2-3 period. However, this forecast 
will assume that these convective bursts will not be organized 
enough to allow the system to regenerate. The latest NHC intensity 
forecast is lower than the previous one, but largely follows the 
HCCA and IVCN consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT  20/0900Z 21.2N 111.3W   35 KT  40 MPH
 12H  20/1800Z 21.3N 112.4W   30 KT  35 MPH
 24H  21/0600Z 21.5N 113.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  21/1800Z 21.6N 115.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  22/0600Z 21.5N 116.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  22/1800Z 21.4N 118.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  23/0600Z 21.3N 119.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  24/0600Z 21.0N 123.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  25/0600Z 20.8N 126.6W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Papin




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