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Post-Tropical Cyclone Olga Forecast Discussion


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000
WTNT42 KNHC 260253
TCDAT2

Post-Tropical Cyclone Olga Discussion Number   3
NWS National Hurricane Center Miami FL       AL172019
1000 PM CDT Fri Oct 25 2019

Earlier this evening, the last 2 passes through Olga made by an Air
Force Reserve Hurricane Hunter aircraft showed that the cyclone
becoming embedded within a cold front. Strong northwesterly flow was
observed within 10 n mi northwest of Olga's center and a sharp
temperature and dew point gradient was measured across the cyclone.
It does not appear that Olga has separated from the front in any
significant way since the plane left. In fact, recent surface
observations suggest that either the front passes through the center
of the cyclone or its circulation has become poorly defined. Based
on all these data, Olga is now classified as post-tropical and this
is the last NHC advisory.

Since Olga is entangled with the front, the winds and seas
associated the front are now considered to be representative of the
overall system. The intensity of the post-tropical cyclone is set at
45 kt based on SFMR winds of 48 kt and flight-level winds of 54 kt
found by the plane behind the front. No substantial change in Olga's
strength is anticipated before it reaches the coast Saturday
morning, and the winds should decrease quickly thereafter. The
post-tropical cyclone is forecast to move quickly up the Mississippi
Valley on Saturday, before turning northeastward toward the Great
Lakes late Saturday or early Sunday. Dissipation is anticipated
before the end of the weekend.

Severe weather, including heavy rain, gusty winds, and isolated
tornadoes will be the primary hazard associated with post-tropical
Olga as it races northward. Coastal flooding is also possible
tonight along portions of the Louisiana coast. For more information
specific to your area, please see products from your local weather
service office at weather.gov.

Key messages:

1. Olga is now a post-tropical cyclone. Detailed information about
hazards related to wind, rainfall, coastal flooding, and tornadoes
can be found in products issued by local National Weather Service
forecast offices, available at weather.gov


FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 27.8N  92.2W   45 KT  50 MPH...POST-TROPICAL
 12H  26/1200Z 31.8N  90.4W   35 KT  40 MPH...POST-TROP/EXTRATROP
 24H  27/0000Z 38.0N  88.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  27/1200Z 43.5N  83.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  28/0000Z...DISSIPATED

$$
Forecaster Zelinsky