####018003903####
WTPZ42 KNHC 201500

TCDEP2

 

Hurricane Norma Discussion Number  12

NWS National Hurricane Center Miami FL       EP172023

900 AM MDT Fri Oct 20 2023

 

The center of Norma is embedded underneath a cold central dense 

overcast this morning. The GOES-West derived motion winds and 

satellite images show healthy upper-level outflow to the north, but 

moderate shear continues to impinge on the south side of the 

hurricane. Recent SSMIS passive microwave images show a ragged 

mid-level eyewall structure, with a thinner ring of convection noted 

on the south and west sides of the inner core. The objective and 

subjective satellite intensity estimates from UW-CIMSS, TAFB, and 

SAB have decreased this morning, and the initial intensity is 

lowered to 95 kt based on a blend of these data. An Air Force 

Reserve Hurricane Hunter aircraft is scheduled to investigate Norma 

later today.

 

Norma is moving north-northwestward (335 degrees) at 7 kt. A gradual 

turn toward the north is expected through Saturday while Norma moves 

within the flow between a mid-level ridge to its east and a mid- to 

upper-level trough to its northwest. This will bring the center of 

Norma near or over the southern tip of Baja California Sur between 

24-36 h. From there, a turn toward the northeast with a slower 

forward speed is forecast as Norma approaches the west-central coast 

of Mexico. The overall track guidance envelope has shifted slightly 

westward this cycle. The updated NHC forecast from 24-72 h has been 

nudged in that direction, generally between the simple (TVCE) and 

corrected (HCCA) consensus aids. This track shows Norma reaching the 

west coast of Mexico on Sunday night and dissipating early next 

week. There are still pronounced speed differences between the 

global and regional models regarding when Norma reaches the coast of 

mainland Mexico, so further adjustments could be required. 

 

Although Norma remains over very warm SSTs, it is moving into a more 

hostile environment. Drier mid-level air and increasing 

southwesterly shear will likely cause continued weakening during the 

next few days. Still, Norma is expected to be a hurricane when it 

moves near or over the southern portion of Baja California Sur on 

Saturday within the Hurricane Warning area. The continued shear and 

potential land interaction with the Baja peninsula will likely cause 

Norma to weaken to a tropical storm on Sunday while it approaches 

the west coast of Mexico. Based on the threat of tropical storm 

conditions there, the government of Mexico has issued a Tropical 

Storm Watch for a portion of the west coast.

 

 

Key Messages:

 

1. Norma is expected to bring hurricane conditions to the far

southern portion of the Baja California peninsula within the

hurricane warning area on Saturday.

 

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

portions of Baja California Sur later today and continue through

Sunday, with heavy rains reaching Sinaloa on Saturday. This rainfall

may produce flash and urban flooding, along with possible mudslides

in areas of higher terrain.

 

3. Norma is forecast to approach the west coast of Mexico as a

tropical storm on Sunday and Sunday night, and a Tropical Storm

Watch has been issued for a portion of that area.

 

 

FORECAST POSITIONS AND MAX WINDS

 

INIT  20/1500Z 19.4N 109.2W   95 KT 110 MPH

 12H  21/0000Z 20.6N 109.6W   85 KT 100 MPH

 24H  21/1200Z 22.1N 109.8W   75 KT  85 MPH

 36H  22/0000Z 23.3N 109.6W   65 KT  75 MPH

 48H  22/1200Z 23.9N 109.1W   60 KT  70 MPH

 60H  23/0000Z 24.3N 108.3W   50 KT  60 MPH

 72H  23/1200Z 24.7N 107.4W   40 KT  45 MPH...INLAND

 96H  24/1200Z 26.0N 106.0W   20 KT  25 MPH...POST-TROP/INLAND

120H  25/1200Z...DISSIPATED

 

$$

Forecaster Reinhart