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Tropical Storm Norma Discussion Number   2
NWS National Hurricane Center Miami FL       EP172023
900 PM MDT Tue Oct 17 2023

Norma is becoming better organized on satellite imagery.  There is 
a developing Central Dense Overcast with very cold cloud tops, and 
some convective banding is evident.  Upper-level outflow is fairly 
well defined over the western semicircle of the circulation.  The 
current intensity estimate is set at 45 kt in agreement with the 
latest Dvorak classifications from TAFB and SAB.

Based on recent center fixes, the motion is now northwestward, or 
around 305/7 kt.  A weak mid-level ridge to the east of Norma 
should maintain a slow northwestward to north-northwestward track 
for the next 48 to 72 hours.  Later in the forecast period, there is 
significant uncertainty in the track, since the model guidance at 3 
to 5 days is not in very good agreement.  The ECMWF and UKMET show a 
weakening cyclone moving along the western side of the guidance 
envelope whereas the GFS show a strong system moving much more to 
the northeast.  The 4- and 5-day official forecast positions
are close to the simple and corrected model consensus predictions.  
However there is low confidence in this forecast, given the spread 
in the model tracks.

For the next couple of days, the storm should be in an atmospheric 
and oceanic environment that will be quite conducive for 
strengthening.  The SHIPS Rapid Intensification (RI) indices and 
the DTOPS probabilities for RI suggest a high likelihood for 
significant strengthening during the next 48 hours or so.  This is 
also reflected in the NHC intensity forecast, which explicitly 
shows RI in the earlier part of the period.  In 3 to 5 days, higher 
south-southwesterly vertical wind shear and drier air is likely to 
inhibit strengthening.  The official forecast is near or above the 
intensity model consensus.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0300Z 13.7N 107.8W   45 KT  50 MPH
 12H  18/1200Z 14.4N 108.2W   55 KT  65 MPH
 24H  19/0000Z 15.5N 108.5W   70 KT  80 MPH
 36H  19/1200Z 16.5N 108.6W   85 KT 100 MPH
 48H  20/0000Z 17.3N 108.8W   90 KT 105 MPH
 60H  20/1200Z 18.2N 109.2W   95 KT 110 MPH
 72H  21/0000Z 19.2N 109.6W   95 KT 110 MPH
 96H  22/0000Z 21.3N 110.2W   90 KT 105 MPH
120H  23/0000Z 22.5N 109.8W   85 KT 100 MPH
 
$$
Forecaster Pasch
 
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