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WTNT44 KNHC 290839
TCDAT4

HURRICANE CRISTOBAL DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014
500 AM AST FRI AUG 29 2014

Cristobal has begun extratropical transition. The cloud pattern has become much less symmetric and central convection has decreased, along with dry air eroding the southern flank of the cyclone. Dvorak classifications are a little lower and support an intensity of about 70 kt for this advisory. The hurricane has now moved across the north wall of the Gulf Stream over much colder waters. This change in environment usually causes a significant weakening of a tropical cyclone, but in this case strong baroclinic forcing should delay the cyclone's demise. Post-tropical Cristobal will likely remain a powerful extratropical cyclone over the north Atlantic through early Sunday. Beyond that time, the system is forecast to merge with another low near southern Greenland and lose its identity.

The hurricane continues to accelerate, and the motion is now 055/43 kt with Cristobal moving rapidly within the mid-latitude flow. Dynamical track guidance indicates that this general motion will continue during the next couple of days with a decrease in forward speed and a small leftward turn due to Cristobal interacting with the low near southern Greenland in the next day or two. The official track forecast is close to the dynamical model consensus and the latest guidance from the Ocean Prediction Center.



FORECAST POSITIONS AND MAX WINDS

INIT 29/0900Z 42.1N 51.7W 70 KT 80 MPH 12H 29/1800Z 45.4N 45.4W 65 KT 75 MPH...POST-TROP/EXTRATROP 24H 30/0600Z 49.3N 39.1W 65 KT 75 MPH...POST-TROP/EXTRATROP 36H 30/1800Z 52.9N 32.3W 60 KT 70 MPH...POST-TROP/EXTRATROP 48H 31/0600Z 59.0N 24.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 72H 01/0600Z...ABSORBED

$$ Forecaster Blake



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