National Weather Service Raw Text Product

051 
FXZS60 NSTU 220020
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago  AS
Issued by National Weather Service Honolulu HI 
220 PM HST Fri Feb 21 2020

.Discussion...
Satellite imagery this afternoon places the center of Tropical 
Cyclone 10F (18P) about 180 west-northwest of Tutuila. The latest
forecast from the Joint Typhoon Warning Center (JTWC) has 10F 
moving to the southwest over the next 18 to 24 hours, and then 
moving to the south away from the Samoan Islands. The JTWC 
forecast shows winds of 34 kts, about 40 mph, extending about 35 
miles to the northeast of the center of the system tonight and up 
to 60 miles to the northeast of the system by tomorrow. This 
will bring tropical storm force winds to Savaii and Upolu, and 
could bring tropical storm force winds to Tutuila and Aunuu 
overnight and tomorrow. The Manua Islands are on the far eastern 
side of the current track for the strong winds, but will certainly
experience high surf and the ongoing possibility of flooding 
rain. 

The morning sounding from Pago Pago reported precipitable water
(PW) values of near 2.5 inches, which corresponded well with the 
satellite derived PW at that time. The latest satellite derived PW
shows plenty of moisture, upwards of 3 inches, over and upstream 
of the Samoan Islands, so expect little change in the amount and 
intensity of rain. While most of today has seen fewer showers than
last night, expect an uptick in the number and intensity of 
showers and thunderstorms tonight and tomorrow as 10F passes the 
region.

As a result of 10F, a Tropical Storm Warning, Flash Flood Watch 
and High Surf Warning remain in effect for Tutuila, Aunuu and the 
Manua Islands. 

The GFS and ECWMF models continue to show a very active trough
remaining over the region through the upcoming week, with 
additional lows developing along the trough. At this time, it 
appears winds will decrease by tomorrow afternoon, but it would be
prudent to closely monitor the forecast as details for the new
week get worked out in the models. What is fairly certain is
additional rain will fall through the upcoming week.

&&

.Marine...
Tropical storm force winds are expected through much of tomorrow
as 10F moves over and to the south of the coastal waters. Strong
winds, rough seas and reduced visibility due to showers and
thunderstorms will be possible during this time, with some 
improvement late Saturday as 10F moves to the south. A Tropical 
Storm Warning is in effect as a result. 

Beyond 10F, the models indicate a very active trough remaining
over the region through the upcoming week, with additional lows
developing along the trough. Anticipate an ongoing potential for 
thunderstorms, but winds and seas should generally trend down. It
would be prudent to closely monitor the forecast as details for 
the new week get worked out in the models.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
Tropical Storm Warning
Flash Flood Watch 
High Surf Warning


&&

$$

M Ballard