510
WTNT42 KNHC 212057
TCDAT2
TROPICAL STORM BERTHA DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL AL022026
400 PM CDT TUE JUL 21 2026
BERTHA REMAINS A SHEARED TROPICAL STORM. THE LOW-LEVEL CENTER IS
EXPOSED AGAIN, WITH BURSTS OF DEEP CONVECTION DISPLACED TO THE SOUTH
BY STRONG NORTHERLY SHEAR. SCATTEROMETER DATA FROM AROUND 1520 UTC
INDICATED THAT THE EXTENT OF THE TROPICAL-STORM-FORCE WIND FIELD WAS
LARGER THAN PREVIOUS ESTIMATES, AND THE INITIAL WIND RADII HAVE BEEN
EXPANDED AS A RESULT. SURFACE OBSERVATIONS TODAY SHOWED THAT
TROPICAL-STORM-FORCE WINDS SPREAD ACROSS SOME COASTAL PORTIONS OF
THE FLORIDA PANHANDLE. THE CENTRAL PRESSURE HAS LEVELED OFF AROUND
995 MB BASED ON THE LAST AIRCRAFT PASS THROUGH THE CENTER, AND THE
INTENSITY IS HELD AT 50 KT BASED ON EARLIER AIRCRAFT DATA. THIS
COULD BE A BIT GENEROUS, BUT AN AIR FORCE RESERVE HURRICANE HUNTER
MISSION SCHEDULED FOR TONIGHT WILL HELP REASSESS THE INTENSITY.
AFTER MOVING NORTHWARD EARLIER TODAY, BERTHA APPEARS TO HAVE RESUMED
A NORTHWESTWARD MOTION (305/5 KT). A MID-LEVEL RIDGE OVER THE
CENTRAL UNITED STATES IS EXPECTED TO BUILD EASTWARD ON WEDNESDAY TO
THE NORTH OF BERTHA. THIS SHOULD BECOME THE DOMINANT STEERING
FEATURE AND CAUSE BERTHA TO MOVE GENERALLY WESTWARD THROUGH MIDWEEK.
THIS TRACK WILL TAKE THE CENTER OF THE STORM NEAR OR ALONG THE
NORTHERN GULF COAST AND TOWARD SOUTHEASTERN LOUISIANA ON WEDNESDAY.
FROM THERE, IT IS STILL UNCLEAR WHETHER BERTHA WILL SURVIVE ITS
INTERACTION WITH LAND AND/OR REDEVELOP UNDER HOSTILE CONDITIONS. THE
GFS AND UKMET MODELS SHOW THE POTENTIAL FOR CENTER REDEVELOPMENT OFF
THE COAST OF LOUISIANA LATE WEDNESDAY, WHILE THE ECMWF AND CANADIAN
MODELS FAVOR A MORE INLAND SOLUTION WITH STEADY WEAKENING. A NOTABLE
CHANGE IS THAT THE TRACK GUIDANCE THIS CYCLE TRENDED FASTER, AND THE
NHC FORECAST WAS SPED UP BETWEEN 24-60 H TO CATCH UP TO THE SIMPLE
AND MULTI-MODEL CONSENSUS AIDS. OTHERWISE, THERE WAS LITTLE
CROSS-TRACK CHANGE WITH THIS FORECAST UPDATE.
BASED ON ITS CURRENT STRUCTURE AND UNRELENTING SHEAR, ADDITIONAL
STRENGTHENING SEEMS UNLIKELY. WHILE CONVECTION SHOULD CONTINUE
PULSING TO THE SOUTH OF BERTHA'S CENTER, THE NHC FORECAST SHOWS
GRADUAL WEAKENING DURING THE NEXT 2-3 DAYS IN AGREEMENT WITH THE
BULK OF THE INTENSITY GUIDANCE. WHILE THIS FORECAST SHOWS BERTHA
SURVIVING AS A SHEARED TROPICAL CYCLONE ACROSS THE NORTHERN GULF, IT
REMAINS POSSIBLE THAT THE SYSTEM DEGENERATES INTO A TROUGH OVER
SOUTHERN LOUISIANA SOONER THAN FORECAST.
BASED ON THE LATEST FORECAST UPDATES, TROPICAL STORM WATCHES AND
WARNINGS HAVE BEEN EXTENDED WESTWARD ALONG THE COAST OF LOUISIANA.
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 21/2100Z 29.4N 87.2W 50 KT 60 MPH
12H 22/0600Z 29.6N 87.9W 45 KT 50 MPH
24H 22/1800Z 29.5N 89.3W 45 KT 50 MPH
36H 23/0600Z 29.3N 91.4W 40 KT 45 MPH...NEAR THE COAST
48H 23/1800Z 29.4N 93.4W 35 KT 40 MPH...OVER WATER
60H 24/0600Z 29.8N 95.6W 30 KT 35 MPH...INLAND
72H 24/1800Z 30.3N 97.6W 25 KT 30 MPH...POST-TROP/INLAND
96H 25/1800Z...DISSIPATED
FORECASTER REINHART
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