Tropical Depression NINE-E (Text)

Tropical Depression Nine-E Discussion Number   6
NWS National Hurricane Center Miami FL       EP092021
500 PM HST Sat Jul 31 2021
The tropical depression's classification as a tropical cyclone is in 
doubt. It has not produced sustained organized deep convection for 
over a day and is nearly devoid of even moderate convection at this 
time. In addition, the surface wind field is poorly defined. A 
prominent swirl noted in the previous forecast package moved quickly
southeastward and dissipated, leaving only a broad, elongated low 
centered east of previous estimates. The most recent TAFB Dvorak fix 
still supports an intensity of 25 kt. 

If organized deep convection does not redevelop soon, the system 
could become a remnant low or open into a trough at any time. Even 
if the depression is able to maintain its status as a tropical 
cyclone, the close proximity of rapidly intensifying Hilda to the 
east will likely prevent it from strengthening during the next 72 
h, and this is reflected in the new NHC intensity forecast. After 
that time, Hilda is forecast to weaken, which could open a window 
for intensification (or re-formation) late in the forecast period. 
The official intensity forecast is now below the intensity consensus 
at most forecast hours. It is worth noting that the operational 
regional hurricane models do not capture storm-to-storm interactions 
very well, and this is likely influencing the relatively high 
intensity forecast produced by the HWRF.

The eastward adjustment of the initial position has necessitated a 
large eastward shift in the forecast track based on the new center 
position. Otherwise, the general reasoning behind the NHC track 
forecast is similar to the previous advisory. A slow, westward to 
west-northwestward motion is expected for the next few days. Beyond 
that time, differences regarding the specifics of any direct 
interaction with Hilda is the primary source of uncertainty in the 
track forecast. Confidence in the forecast, especially at that long 
range, remains low. The NHC forecast is based primarily on a 
consensus of the GFS and ECMWF global models.
INIT  01/0300Z 11.5N 127.5W   25 KT  30 MPH
 12H  01/1200Z 11.8N 128.4W   25 KT  30 MPH
 24H  02/0000Z 12.0N 130.0W   30 KT  35 MPH
 36H  02/1200Z 12.2N 131.5W   30 KT  35 MPH
 48H  03/0000Z 12.5N 133.0W   30 KT  35 MPH
 60H  03/1200Z 12.9N 134.2W   30 KT  35 MPH
 72H  04/0000Z 13.5N 135.6W   30 KT  35 MPH
 96H  05/0000Z 14.5N 138.0W   35 KT  40 MPH
120H  06/0000Z 15.5N 141.0W   40 KT  45 MPH
Forecaster Zelinsky

Standard version of this page

Alternate Formats
About Alternates - E-Mail Advisories - RSS Feeds

Cyclone Forecasts
Latest Advisory - Past Advisories - About Advisories

Marine Forecasts
Latest Products - About Marine Products

Tools & Data
Satellite Imagery - US Weather Radar - Aircraft Recon - Local Data Archive - Forecast Verification - Deadliest/Costliest/Most Intense

Learn About Hurricanes
Storm Names Wind Scale - Prepare - Climatology - NHC Glossary - NHC Acronyms - Frequently Asked Questions - AOML Hurricane-Research Division

About Us
About NHC - Mission/Vision - Other NCEP Centers - NHC Staff - Visitor Information - NHC Library

Contact Us

NOAA/ National Weather Service
National Centers for Environmental Prediction
National Hurricane Center
11691 SW 17th Street
Miami, Florida, 33165-2149 USA
Privacy Policy
About Us
Career Opportunities
Page last modified: Friday, 31-Dec-2021 12:09:56 UTC