老農民版夜神月

NHC21Z報判定Elsa已轉溫

637
WTNT45 KNHC 092042
TCDAT5

Post-Tropical Cyclone Elsa Discussion Number  39
NWS National Hurricane Center Miami FL       AL052021
500 PM AST Fri Jul 09 2021

Surface, satellite, and radar data indicate that Elsa's deep
convection remains limited to a shield north of its center and that
a front extends through the center of the cyclone. For those
reasons, Elsa was designated as a post-tropical cyclone at 1800 UTC.
Surface observations of sustained winds a little above 40 kt were
reported across portions of southern Massachusetts and the nearby
waters as Elsa crossed the state, so the intensity estimate remains
45 kt.

Elsa is moving quickly just off the northeast coast of the U.S. with
an initial motion estimate of 040/27 kt. A faster northeastward
motion is expected tonight and on Saturday while the system remains
embedded within a deep mid-latitude trough. Very little change was
made to the NHC track forecast. All available guidance indicates
that Elsa will gradually weaken during the next couple of days. The
GFS, ECMWF, and CMC global models now indicate the cyclone will open
into a trough within the next 48 h or so, and this is reflected in
the NHC forecast.

It is estimated that center of Elsa made landfall along the coast of
Long Island near Southampton around 1430 UTC (10:30 am EDT), and
again near Watch Hill, Rhode Island near 1615 UTC (12:15 pm EDT).
Elsa's classification at the time the center crossed the coast will
be determined in the post-storm analysis. It should also be noted
that the landfall position had little bearing on the location or
timing of the strong winds and heavy rain which were well removed
from the cyclone's center.

Since Elsa is now post-tropical and all coastal tropical storm
warnings have been discontinued, this is the last NHC advisory.  
Additional information on this system can be found in High Seas
Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and online at
ocean.weather.gov/shtml/NFDHSFAT1.php


Key Messages:

1. As Elsa moves off the coast of Maine through this evening, heavy
rainfall could lead to considerable flash and urban flooding.

2. Gusty winds will continue across portions of the southern New
England coast during the next couple of hours. The post-tropical
cyclone is also expected to bring gusty winds to portions of
Atlantic Canada tonight and Saturday.


FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 43.0N  69.5W   45 KT  50 MPH...POST-TROPICAL
12H  10/0600Z 46.2N  64.7W   40 KT  45 MPH...POST-TROP/EXTRATROP
24H  10/1800Z 50.3N  56.1W   40 KT  45 MPH...POST-TROP/EXTRATROP
36H  11/0600Z 54.7N  46.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
48H  11/1800Z...DISSIPATED

$$
Forecaster Zelinsky