ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM
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
NNNN