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Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Fri Sep 17 2021

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The Weather Prediction Center is issuing advisories on 
Post-Tropical Cyclone Nicholas, located over Louisiana. 

1. Recent satellite images indicate that a new and better-defined 
center of circulation has developed in association with a low 
pressure area located about 250 miles east of Norfolk, Virginia.  
In addition, shower and thunderstorm activity is becoming more 
organized near this new center.  If these development trends 
continue, then a tropical depression or tropical storm is likely to 
form later today or tonight while the low moves toward the 
northeast or east-northeast at 10 to 15 mph, away from the United 
States Mid-Atlantic and Northeast coasts.  The low is expected to 
transform into a non-tropical gale-force low Saturday or Saturday 
night while it is located south of Atlantic Canada, and it is 
likely to bring strong winds and heavy rains to portions of 
Newfoundland by Sunday and Sunday night.  This system is also 
expected to bring high surf to portions of the Mid-Atlantic and 
Northeast U.S. coasts and Atlantic Canada through this weekend.  
Additional information on this system, including gale warnings, can 
be found in High Seas Forecasts issued by the NOAA Ocean Prediction 
Center. 
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 5 days...high...80 percent.

2. Showers and thunderstorms associated with a tropical wave and broad 
area of low pressure located about midway between the Lesser 
Antilles and the Cabo Verde Islands have become a little better 
organized since yesterday.  Environmental conditions are expected 
to be conducive for further development during the next couple of 
days, and a tropical depression is likely to form over the weekend 
or early next week while moving toward the west-northwest at about 
15 mph across the central tropical Atlantic and then near the 
northern Leeward Islands by Monday and Tuesday.  Upper-level winds 
could become less conducive for development over the southwestern 
Atlantic by the early to middle part of next week.  Interests in 
the Leeward Islands should monitor the progress of this system 
during the next few days.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...80 percent.

3. A broad area of low pressure located a few hundred miles 
south-southeast of the Cabo Verde Islands continues to produce 
disorganized showers and thunderstorms.  This system is expected to 
move toward the west and then northwest at 5 to 10 mph over the far 
eastern Atlantic, and some gradual development is possible over the 
weekend before upper-level winds increase and the low moves over 
cooler waters.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...30 percent.

Public advisories issued by the Weather Prediction Center on 
Post-Tropical Cyclone Nicholas can be found under AWIPS header 
TCPAT4, WMO header WTNT34 KWNH, and on the web at 
https://www.wpc.ncep.noaa.gov or hurricanes.gov

High Seas Forecasts for the system off the United States 
Mid-Atlantic coast issued by the NOAA Ocean Prediction Center can 
be found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and 
online at ocean.weather.gov/shtml/NFDHSFAT1.php

Forecaster Berg