####018002479####
WTPZ42 KNHC 180239

TCDEP2

 

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