000
WTPZ42 KNHC 171445
TCDEP2

Tropical Storm Norma Discussion Number  13
NWS National Hurricane Center Miami FL       EP172017
900 AM MDT Sun Sep 17 2017

Deep convection associated with Norma is restricted to a curved
band to the north and the west of the center.  Dvorak
classifications continue to fall and a blend of the SAB/TAFB
numbers indicates initial maximum winds of 40 kt, consistent with
some weakening since the overnight ASCAT pass.

Norma should continue to decay due to the combination of dry air,
cooler SSTs, and a convergent upper-troposphere.  Transition to a
remnant low is expected in about three days.  The official
intensity forecast is based upon the IVCN consensus technique and
is slightly lower than the previous advisory.

Norma is moving north-northwestward at about 4 kt, steered by a
deep-layer ridge over the Gulf of Mexico.  The tropical storm
should turn toward the northwest or west-northwest at about the
same rate of forward speed during the next couple of days.  By days
3 to 5, Norma's remnant low should meander west of the southern tip
of Baja California.  The official track forecast is based upon a
blend of the HFIP Corrected Consensus Approach and the ECMWF - the
best performing model for this system.  The new prediction is
slightly west of the previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 20.9N 110.5W   40 KT  45 MPH
 12H  18/0000Z 21.4N 110.9W   35 KT  40 MPH
 24H  18/1200Z 21.7N 111.6W   35 KT  40 MPH
 36H  19/0000Z 22.0N 112.5W   30 KT  35 MPH
 48H  19/1200Z 22.2N 113.2W   25 KT  30 MPH
 72H  20/1200Z 22.8N 114.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  21/1200Z 23.5N 114.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  22/1200Z 24.0N 114.0W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Landsea