Advisories

000
WTNT42 KNHC 220242
TCDAT2
 
Tropical Storm Bertha Discussion Number  11
NWS National Hurricane Center Miami FL       AL022026
1000 PM CDT Tue Jul 21 2026

North-northeasterly vertical wind shear persists over Bertha this 
evening.  The storm continues to produce strong convection with 
cloud tops colder than -70 deg C over its southern semicircle.  
Reconnaissance aircraft and surface observations indicate that the 
low-level center is near the northeastern edge of the main 
convective mass.  Tail Doppler radar winds from the NOAA aircraft 
indicate that the vortex is tilted southward with height, likely due 
to the shear.  The central pressure is about the same as earlier 
today and peak flight-level winds from the Air Force and NOAA 
Hurricane Hunter aircraft support maintaining the current intensity 
at 50 kt, although this may be slightly generous.

Based on the aircraft and satellite center fixes, the initial motion 
estimate is westward, or 270/5 kt. There is little change in the 
track forecast reasoning from the previous advisory.  Bertha had 
been situated between two mid-level high centers, but the larger 
high to the northwest, over the south-central United States, will 
likely become the dominant steering mechanism.  Bertha should move 
generally westward on the southern side of this high, near or along 
the northern Gulf coast, for the next 36-48 hours.  Then the 
cyclone, if it survives, should move over portions of southeastern 
Texas.  The official track forecast is similar to the previous NHC 
prediction and close to the corrected consensus and Google DeepMind 
guidance.

Bertha is likely to remain in an environment of strong vertical wind 
shear and dry mid-level air for the next couple of days. 
Additionally, the storm is expected to move at least partially over 
southeastern Louisiana in 24 hours or so.  Given the hostile 
atmospheric conditions and partial interaction with land, a 
weakening trend is likely to begin tomorrow.  The NHC intensity 
forecast is close to the corrected consensus guidance.
 
Key Messages:
 
1. Tropical storm conditions are expected to spread westward along
portions of the northern Gulf Coast from the Florida Panhandle
westward to southeastern Louisiana, including the Metro New Orleans
area, through Wednesday night. Tropical storm conditions are
possible for portions of the southwestern coast of Louisiana
Wednesday night and Thursday.
 
2. A Coastal Flood Warning is in effect for the Mississippi and
Louisiana coastlines, where moderate coastal flooding is expected.
 
3. Interests elsewhere in extreme western Louisiana and along the
Upper Texas Coast should monitor the progress of this system, as
additional watches or warnings could be required for portions of
that area.
 
4. Isolated areas of flash flooding will be possible through
Thursday along the Gulf Coast from the western Florida Panhandle
into southern Louisiana.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/0300Z 29.4N  87.7W   50 KT  60 MPH
 12H  22/1200Z 29.4N  88.6W   45 KT  50 MPH
 24H  23/0000Z 29.4N  90.2W   40 KT  45 MPH...INLAND
 36H  23/1200Z 29.3N  92.4W   35 KT  40 MPH...OVER WATER
 48H  24/0000Z 29.3N  95.0W   30 KT  35 MPH...INLAND
 60H  24/1200Z 29.5N  97.0W   25 KT  30 MPH...POST-TROP/INLAND
 72H  25/0000Z...DISSIPATED
 
$$
Forecaster Pasch