706
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
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