000
WTNT41 KNHC 080233
TCDAT1

SUBTROPICAL STORM ANA DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012015
1100 PM EDT THU MAY 07 2015

Satellite imagery shows some increase in deep convection this
evening, and the low pressure system off the southeast U.S. coast
is now being designated as a subtropical storm.  Based on adjusted
SFMR winds from a hurricane hunter aircraft that has been
investigating the system, the current intensity is set at 40
kt.  Data from the aircraft also show that the radius of maximum
winds has decreased somewhat from earlier today, but at 80 n mi it
is still too large to justify classifying Ana as a tropical cyclone
at this time.  Since there has been more deep convection occurring
near the center over the past several hours, it is becoming more
likely that Ana will make the transition into a tropical storm
within the next day or so.  The storm should remain situated near or
over the Gulf Stream for the next 24-36 hours, which would allow for
some slight strengthening.  Later in the period, as the cyclone
approaches the coast, weakening is expected due to the influence of
cooler shelf waters.

The system has not moved much over the past 24 hours and the
initial motion estimate is 350/2.  Ana is likely to remain located
to the south of a stubborn mid-tropospheric blocking pattern for the
next 48 hours or so.  Global models show the block breaking down
over the weekend, which should allow Ana to move inland over the
southeastern U.S. Near the end of the forecast period, the system
should accelerate northeastward in the flow ahead of a broad trough.
The official track forecast is close to the dynamical model
consensus.

We appreciate the assistance of the Air Force Hurricane Hunters for
providing valuable observations, given their limited resources
prior to the start of the regular Atlantic Hurricane Season.

Note that the name Ana is pronounced AH-nah.

FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 31.5N  77.6W   40 KT  45 MPH
 12H  08/1200Z 31.6N  77.7W   45 KT  50 MPH
 24H  09/0000Z 31.7N  77.8W   45 KT  50 MPH
 36H  09/1200Z 31.9N  78.0W   40 KT  45 MPH
 48H  10/0000Z 32.3N  78.6W   35 KT  40 MPH
 72H  11/0000Z 33.4N  79.3W   30 KT  35 MPH...INLAND
 96H  12/0000Z 36.1N  77.8W   25 KT  30 MPH...POST-TROP/INLAND
120H  13/0000Z 41.0N  71.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Pasch