161
WTNT42 KNHC 210252
TCDAT2
TROPICAL STORM BERTHA DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL022026
1000 PM CDT MON JUL 20 2026
THE SYSTEM HAS BECOME A LITTLE BETTER ORGANIZED WITH AN AREA OF DEEP
CONVECTION OVER THE SOUTHERN SEMICIRCLE SHOWING SLIGHT CURVATURE AND
LIMITED CURVED CONVECTIVE BANDS OVER THE NORTHWESTERN QUADRANT.
FLIGHT-LEVEL WINDS FROM BOTH NOAA AND AIR FORCE HURRICANE HUNTER
AIRCRAFT WITHIN THE CONVECTION TO THE SOUTHWEST AND SOUTHEAST OF THE
CENTER INDICATE THAT THE INTENSITY IS NEAR 35 KT, SO THE SYSTEM HAS
BEEN UPGRADED TO TROPICAL STORM BERTHA. THE AIRCRAFT ALSO REPORTED
THAT THE CENTRAL PRESSURE HAS DROPPED ABOUT 6 MB SINCE THIS
AFTERNOON. THE STORM HAS WELL-DEFINED UPPER-LEVEL OUTFLOW TO THE
SOUTH AND SOUTHWEST, BUT OUTFLOW IS LIMITED OVER THE NORTHERN
SEMICIRCLE.
THERE HAVE BEEN SEVERAL CENTER FIXES FROM THE AIRCRAFT WHICH
INDICATE VERY SLOW, ERRATIC MOTION. SINCE THE STORM HAS MOVED
VERY LITTLE OVERALL THIS EVENING, THE BEST ESTIMATE FOR THE INITIAL
MOTION IS NEARLY STATIONARY. BERTHA REMAINS SANDWICHED BETWEEN TWO
MID-LEVEL SUBTROPICAL HIGH CELLS, IN A REGION OF WEAK STEERING
CURRENTS. THE HIGH TO THE NORTHWEST OF THE STORM IS FORECAST TO
BECOME THE DOMINANT STEERING INFLUENCE WHICH SHOULD INDUCE A
WEST-NORTHWESTWARD OR WESTWARD MOTION OVER THE NEXT FEW DAYS. THE
OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS NHC PREDICTION,
ON THE SOUTHERN SIDE OF THE GUIDANCE SUITE AND CLOSE TO THE GOOGLE
DEEPMIND ENSEMBLE MEAN.
BERTHA IS BEING AFFECTED BY SIGNIFICANT NORTH-NORTHEASTERLY VERTICAL
WIND SHEAR. DYNAMICAL GUIDANCE INDICATES THAT THIS SHEAR WILL
INCREASE DURING THE NEXT COUPLE OF DAYS. THIS SHOULD LIMIT
INTENSIFICATION OF THE STORM BEFORE THE CENTER REACHES THE COAST.
SIMULATED SATELLITE IMAGERY FROM THE GLOBAL MODELS SHOWS THE DEEP
CONVECTION NEAR OR OFFSHORE OF THE COASTLINE, LIKELY DUE TO THE
SHEAR. UNFAVORABLE ATMOSPHERIC CONDITIONS ALONG WITH THE
INTERACTION OF LAND SHOULD PREVENT STRENGTHENING LATE IN THE
FORECAST PERIOD. THE OFFICIAL INTENSITY FORECAST IS ON THE HIGH
SIDE OF THE MODEL GUIDANCE.
KEY MESSAGES:
1. BERTHA IS EXPECTED TO BRING TROPICAL STORM CONDITIONS TO PORTIONS
OF THE GULF COAST FROM ALABAMA WESTWARD TO SOUTHEASTERN LOUISIANA
TUESDAY NIGHT AND WEDNESDAY, WHERE A TROPICAL STORM WARNING IS IN
EFFECT. TROPICAL STORM CONDITIONS ARE POSSIBLE FOR PORTIONS OF THE
FLORIDA PANHANDLE, METRO NEW ORLEANS, AND THE SOUTHERN GULF COAST OF
LOUISIANA, WHERE A TROPICAL STORM WATCH IS IN EFFECT.
2. A STORM SURGE WATCH IS IN EFFECT FOR THE ALABAMA, MISSISSIPPI,
AND SOUTHEASTERN LOUISIANA COASTS, WHERE A LIFE-THREATENING STORM
SURGE IS POSSIBLE.
3. INTERESTS ELSEWHERE IN LOUISIANA AND TEXAS SHOULD MONITOR THE
PROGRESS OF THIS SYSTEM, AS ADDITIONAL WATCHES OR WARNINGS COULD BE
REQUIRED FOR PORTIONS OF THAT AREA ON TUESDAY.
4. AREAS OF FLASH FLOODING WILL BE POSSIBLE THROUGH THURSDAY ALONG
THE GULF COAST AND ADJACENT INLAND LOCATIONS FROM WESTERN FLORIDA
NORTH OF FORT MYERS TO SOUTHERN LOUISIANA WITH ISOLATED INSTANCES OF
FLASH FLOODING POSSIBLE WESTWARD INTO PORTIONS OF TEXAS COAST LATER
IN THE WEEK.
FORECAST POSITIONS AND MAX WINDS
INIT 21/0300Z 28.2N 85.9W 35 KT 40 MPH
12H 21/1200Z 28.8N 86.6W 40 KT 45 MPH
24H 22/0000Z 29.1N 87.3W 45 KT 50 MPH
36H 22/1200Z 29.3N 88.1W 45 KT 50 MPH
48H 23/0000Z 29.3N 89.4W 40 KT 45 MPH...INLAND
60H 23/1200Z 29.3N 90.7W 35 KT 40 MPH...INLAND
72H 24/0000Z 29.3N 92.1W 30 KT 35 MPH...OVER WATER
96H 25/0000Z 29.3N 94.6W 25 KT 30 MPH...OVER WATER
120H 26/0000Z 29.3N 97.0W 20 KT 25 MPH...POST-TROPICAL
FORECASTER PASCH
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