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Tropical Depression Five-E Discussion Number 1
NWS National Hurricane Center Miami FL EP052023
400 PM CDT Mon Jul 31 2023
Through this morning and afternoon, the system we have been
monitoring several hundred miles offshore to the south of the coast
of Mexico has improved in organization on satellite imagery, with
plenty of curved convective bands along its northern semicircle. A
couple of bulls-eye ASCAT passes earlier this afternoon indicated
that a closed circulation had formed at the surface, with believable
25-30 kt winds on its northern flank. We also received a subjective
Dvorak intensity estimate of T2.0/30-kt from TAFB this afternoon.
The aforementioned data supports initiating advisories on the system
as a tropical depression, with maximum sustained winds of 30 kt.
The initial motion of the depression is north of due west at 280/12
kt. A prominent mid-level subtropical ridge is located poleward of
the cyclone and is expected to move westward with the system
throughout the forecast period. The orientation of the ridge ahead
of the system may even result in a west-southwestward motion by the
middle to latter part of this week. The track guidance is in fairly
good agreement, especially for a system that has only recently
formed, though some speed differences exist towards the end of the
forecast period. The initial NHC track forecast has opted to remain
close to the reliable consensus aids, roughly in between the faster
HCCA and slower TVCE guidance.
Environmental conditions appear quite favorable for intensification
over the next few days. Both the GFS- and EC-based SHIPS guidance
shows deep-layer vertical wind shear remaining 10 kt or below
throughout the forecast period as sea-surface temperatures
underneath the system remain above 28 C for the next 3 days. While
there will likely be some mid-level dry air lurking near the system
during this time-span, this may not harm the cyclone as much as
just keeping its convective core small. In fact, most of the
hurricane-regional models show the system significantly intensifying
as a small tropical cyclone during the forecast period. The NHC
intensity forecast follows this evolution, with significant
intensification expected, especially between 36-72 h after the
system has an opportunity to develop an inner core that takes better
advantage of the favorable conditions. A period of rapid
intensification during this time frame is also possible. This
initial intensity forecast is in best agreement with the SHIPS
guidance this cycle, and is roughly a split between the higher
HWRF/HMON and lower HAFS-A/B runs.
FORECAST POSITIONS AND MAX WINDS
INIT 31/2100Z 14.8N 104.4W 30 KT 35 MPH
12H 01/0600Z 15.5N 106.4W 35 KT 40 MPH
24H 01/1800Z 15.8N 109.0W 40 KT 45 MPH
36H 02/0600Z 15.5N 111.7W 50 KT 60 MPH
48H 02/1800Z 15.1N 114.3W 65 KT 75 MPH
60H 03/0600Z 14.7N 116.7W 75 KT 85 MPH
72H 03/1800Z 14.3N 119.3W 85 KT 100 MPH
96H 04/1800Z 13.3N 125.1W 90 KT 105 MPH
120H 05/1800Z 12.7N 130.9W 90 KT 105 MPH
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Forecaster Papin
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