[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 091446
TCDAT5

Tropical Storm Elsa Discussion Number  38
NWS National Hurricane Center Miami FL       AL052021
1100 AM EDT Fri Jul 09 2021

The extratropical transition of Elsa is well underway.  A frontal
boundary located over southern New England nearly wraps into the
circulation center, and the primary area of cold cloud tops and
heavy rainfall has now shifted to the northwestern portion of the
cyclone.  Elsa is expected to complete its extratropical transition
this afternoon.  Buoy and surface observations indicate that the
cyclone's intensity has changed little since early this morning.
Based on those data, Elsa's peak winds and minimum pressure
remain 45 kt and 1000 mb for this advisory, respectively.

Elsa continues to move quickly northeastward or 045/27 kt.  The
post-tropical cyclone is forecast to continue accelerating
northeastward over the next day or two as it remains embedded
within deep-layer southwesterly flow.  After 48 hours, the system is
expected to slow before it dissipates over the north Atlantic
around day 3.  The track guidance remains in good agreement, but has
shifted slightly southward after 24 hours and the NHC forecast has
been adjusted accordingly.

Little change in strength is anticipated in the short-term as Elsa
completes its extratropical transition.  After that time, gradual
weakening is anticipated and the wind speed forecast calls for the
system to weaken below gale-force in a couple of days.  The global
models show the post-tropical cyclone dissipating over the north
Atlantic by early next week, and the official forecast follows
suit.

Key Messages:

1. As Elsa moves near southern and coastal New England today, heavy
rainfall could lead to considerable flash and urban flooding.

2. Tropical storm conditions are expected to continue in portions
of the warning area in Long Island and southern New England
through this afternoon. Gusty winds are expected over portions of
Atlantic Canada tonight and Saturday.


FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 41.0N  72.1W   45 KT  50 MPH
 12H  10/0000Z 44.0N  67.7W   45 KT  50 MPH...POST-TROP/EXTRATROP
 24H  10/1200Z 48.4N  60.3W   40 KT  45 MPH...POST-TROP/EXTRATROP
 36H  11/0000Z 52.2N  51.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  11/1200Z 56.5N  41.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 60H  12/0000Z 60.0N  32.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  12/1200Z...DISSIPATED

$$
Forecaster Brown
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