####018003089####
WTPZ42 KNHC 190856

TCDEP2

 

Hurricane Norma Discussion Number   7

NWS National Hurricane Center Miami FL       EP172023

300 AM MDT Thu Oct 19 2023

 

Norma has rapidly intensified into a major hurricane. Overnight, a

20 n mi wide eye emerged on infrared satellite imagery, with cold

cloud tops wrapping around the eyewall and some evidence of warming

within the eye.  Subjective intensity estimates from TAFB and SAB

were both T5.5/102 kt, and the initial intensity was raised to 105

kt, slightly above the estimates given the improved structural

organization.

 

The hurricane is likely nearing its peak intensity and environmental

conditions are expected to become increasingly hostile soon.  Global

model guidance is already analyzing moderate southerly deep-layer

wind shear over Norma.  However, there is still some potential for

strengthening in the next 12 h.  Beyond that time frame, strong

shear and dry mid-level humidities will likely induce a gradual

weakening trend through the end of the forecast period.  The latest

NHC peak intensity forecast has been raised to 115 kt in 12 h and is

on the upper bound of the intensity guidance envelope.

 

Norma is moving northward slower than expected, at an estimated 5

kt.  There is still a considerable spread in the model guidance

envelope and therefore a high level of uncertainty in the track

forecast.  The ECMWF continues to favor a slower forward speed that

essentially stalls Norma off the southern coast of the Baja

California peninsula this weekend and early next week.  This is

contrasted by the GFS which shows Norma accelerating and turning

northeastward prior to the peninsula in stronger steering flow.  The

official forecast is a blend of these solutions and shows the center

of Norma reaching the southern tip of the Baja California peninsula

in 72 h.  A slow northeastward motion is possible by days 4 and 5.

Based on the possibility of hurricane-force winds within 48 hours,

the government of Mexico has issued a hurricane watch for the

extreme southern portion of the Baja California peninsula.

 

 

Key Messages:

 

1. Norma is expected to be near hurricane strength as it approaches

the southern tip of Baja California and a hurricane watch has been

issued for that area.

 

2. Heavy rainfall from Norma will begin to impact the far southern

portions of Baja California Sur late Friday, continuing through

Sunday.  This rainfall may produce flash and urban flooding, along

with possible mudslides in areas of high terrain.

 

 

FORECAST POSITIONS AND MAX WINDS

 

INIT  19/0900Z 16.7N 107.7W  105 KT 120 MPH

 12H  19/1800Z 17.5N 108.1W  115 KT 130 MPH

 24H  20/0600Z 18.6N 108.5W  100 KT 115 MPH

 36H  20/1800Z 19.8N 109.1W   90 KT 105 MPH

 48H  21/0600Z 21.2N 109.6W   80 KT  90 MPH

 60H  21/1800Z 22.3N 109.6W   70 KT  80 MPH

 72H  22/0600Z 23.0N 109.7W   60 KT  70 MPH

 96H  23/0600Z 23.4N 109.3W   50 KT  60 MPH

120H  24/0600Z 24.0N 108.4W   40 KT  45 MPH

 

$$

Forecaster Bucci