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Hurricane Delta Discussion Number  12
NWS National Hurricane Center Miami FL       AL262020
1000 AM CDT Wed Oct 07 2020
 
Satellite and surface observations show that Delta made landfall 
along the northeastern coast of the Yucatan peninsula around 1030 
UTC near Puerto Morelos.  A WeatherFlow observing site at Puerto 
Morelos reported near calm winds and a minimum pressure of around 
972 mb when the center passed that location.  Another WeatherFlow 
site near Cancun reported peak sustained winds of 73 kt with a gust 
to 92 kt. Hurricane-force winds gusts were also reported at an 
observing site on Cozumel.  Since landfall, Delta has moved across 
the northeastern portion of the Yucatan peninsula and is now about 
the emerge off the northern coast of the peninsula into the 
southern Gulf of Mexico. Assuming some weakening has occurred, the 
initial intensity has been set at 90 kt, but this could be a little 
generous.  An Air Force Reserve Hurricane Hunter aircraft is 
scheduled to investigate Delta early this afternoon.  A NOAA P-3 
aircraft has been preforming a Tail Doppler Radar mission this 
morning.
 
Once Delta moves over the southern Gulf of Mexico, warm waters and
expected low vertical wind shear conditions are expected to allow
for re-strengthening during the next 24 to 36 hours. After 48
hours, increasing southwesterly shear and cooler waters over the
northern Gulf are likely to induce some weakening.  The intensity
guidance has trended downward this cycle, and the NHC forecast has
been adjusted accordingly.  Delta, however is still expected to
regain major hurricane status and the wind field is likely to grow
in size during its approach to the northern Gulf coast, which will 
increase the storm surge and wind threats.  Regardless of Delta's 
landfall intensity, life-threatening storm surge and strong winds 
are likely over a large portion of the northwestern and northern 
Gulf coast, which has necessitated the issuance of Storm Surge, 
Hurricane, and Tropical Storm watches for portions of that area.
 
Delta is moving northwestward or 305/15 kt. The hurricane should 
continue moving northwestward around the southwestern portion of a 
subtropical ridge that extends over Florida and the northeastern 
Gulf of Mexico through early Thursday.  After that time, a 
developing mid-level trough over the south-central United States 
should cause Delta to slow down and turn north-northwestward on 
Thursday.  Delta is forecast to begin accelerating northward or 
north-northeastward toward the northern Gulf coast ahead of the 
trough Thursday night and Friday.  There has been little change to 
the early portion of the track forecast, but there has been a little 
westward shift in the guidance envelope after 24 hours, and the NHC 
forecast has been moved in that direction.  The new forecast track 
lies near or just left of the TVCA multi-model consensus and a 
little right of the HFIP corrected consensus aid, again close to the 
GFS, GFS ensemble mean, and UKMet models. 

Key Messages:
 
1. Life-threatening storm surge and dangerous winds will continue 
within portions of the northern Yucatan Peninsula of Mexico into 
early afternoon. Heavy rainfall, which could lead to significant 
flash flooding, will affect the northern Yucatan Peninsula through 
early Thursday. 

2. Delta is expected to grow in size as it approaches the northern 
Gulf Coast, where there is an increasing likelihood of life- 
threatening storm surge and dangerous hurricane-force winds 
beginning Friday, particularly for portions of the Louisiana coast. 
Storm Surge and Hurricane Watches are in effect, and residents in 
these areas should follow advice given by local officials.  

3. Flash, urban, small stream, and minor river flooding is likely 
Friday through Saturday from portions of the central Gulf Coast 
northward into portions of the Lower to Middle Mississippi Valley. 
As Delta moves farther inland, additional heavy rainfall is 
expected in the Ohio Valley and Mid Atlantic this weekend. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/1500Z 21.4N  88.0W   90 KT 105 MPH...INLAND
 12H  08/0000Z 22.8N  90.2W   95 KT 110 MPH...OVER WATER
 24H  08/1200Z 24.3N  92.4W  100 KT 115 MPH
 36H  09/0000Z 26.0N  93.3W  105 KT 120 MPH
 48H  09/1200Z 28.1N  93.3W  105 KT 120 MPH
 60H  10/0000Z 30.8N  92.4W   70 KT  80 MPH...INLAND
 72H  10/1200Z 33.2N  90.9W   40 KT  45 MPH...INLAND
 96H  11/1200Z 36.5N  86.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  12/1200Z 39.5N  81.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Brown
 
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