ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM Tropical Storm Sandra Discussion Number 2 NWS National Hurricane Center Miami FL EP192021 100 PM PST Sun Nov 07 2021 This afternoon, deep-convective activity has decreased in coverage and intensity, shearing off to the east and revealing a well-defined low-level circulation. Even though the convection has waned, an earlier 1549 UTC ASCAT-A pass revealed a fairly large region of 30-35 kt winds primarily to the east of the circulation. Based primarily on the scatterometer data, TD 19-E was upgraded to 35-kt Tropical Storm Sandra at 1800 UTC and that will be the intensity for this advisory. It should be noted that the satellite presentation was better organized this morning, when both SAB and TAFB provided CI 2.5/35 kt estimates, and it is likely this system was already tropical storm earlier today. The exposed low-level circulation has been moving left of the previous forecast track this afternoon, with the current estimated motion at 285/10 kt. The track guidance is insistent that a more poleward motion will resume soon, but its possible the storm's direction of motion is dependent on additional down-shear convective bursts helping to tug the center more poleward. As the system becomes more vertically shallow, the west-northwest motion should bend more westward and then west-southwestward as the circulation gradually decays. The track guidance this cycle is further to the left in the short-term, mainly based on the initial motion, but corrects to near the same place by the end of the forecast period. The latest NHC track forecast has also been shifted further south early on, but ends up near the previous one by 60 hours, close to the tightly clustered consensus aids. Assuming that convection will redevelop near or east of the center, possibly during the diurnal convective maximum tonight, Sandra is expected to maintain its intensity for the next 12-24 hours. Thereafter, increasing vertical wind shear should help to import drier mid-level air that should finish off any additional convection. Forecast simulated IR imagery from the GFS and ECMWF suggests Sandra becoming devoid of convection by 48-60 h, and the latest NHC forecast still shows the cyclone becoming a post-tropical remnant low by this time frame. The NHC intensity forecast is in decent agreement with the intensity guidance and is quite similar to the latest SHIPS/LGEM, though remains lower than the HWRF/HMON runs. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 14.0N 115.2W 35 KT 40 MPH 12H 08/0600Z 14.5N 116.1W 35 KT 40 MPH 24H 08/1800Z 15.3N 117.5W 35 KT 40 MPH 36H 09/0600Z 15.7N 119.0W 30 KT 35 MPH 48H 09/1800Z 15.5N 121.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 10/0600Z 15.0N 124.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 10/1800Z...DISSIPATED $$ Forecaster Papin NNNN
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
NOAA/
National Weather Service
National Centers for Environmental Prediction
National Hurricane Center
11691 SW 17th Street
Miami, Florida, 33165-2149 USA
nhcwebmaster@noaa.gov
Disclaimer
Privacy Policy
Credits
About Us
Glossary
Career Opportunities
Page last modified: Friday, 31-Dec-2021 12:10:15 UTC