BULLETIN
HURRICANE BERTHA ADVISORY NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
11:00 AM AST MON JUL 07 2008
BERTHA STRENGTHENS OVER THE CENTRAL ATLANTIC, COULD REACH CATEGORY TWO
INTENSITY LATER TODAY...
AT 11:00 AM Atlantic Standard Time, 15:00Z, THE CENTER OF HURRICANE BERTHA
WAS LOCATED
NEAR LATITUDE 19.6 NORTH, LONGITUDE 51.3 WEST, OR ABOUT 775 MILES, 1250 KM
EAST OF THE NORTHERN LEEWARD ISLANDS. BERTHA IS MOVING TOWARD THE
WEST-NORTHWEST NEAR 15 MPH, 24 KM HR. A GRADUAL TURN TOWARDS THE NORTHWEST,
WITH A REDUCTION IN FORWARD SPEED, IS EXPECTED OVER THE NEXT COUPLE OF DAYS.
MAXIMUM SUSTAINED WINDS ARE NEAR 90 MPH, 150 KM HR, WITH HIGHER GUSTS. SOME
STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS, AND BERTHA COULD BECOME
A CATEGORY TWO HURRICANE LATER TODAY OR TONIGHT.
HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 25 MILES, 35 KM FROM THE CENTER,
AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 115 MILES, 185 KM.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB, 29.35 INCHES.
REPEATING THE 11:00 AM Atlantic Standard Time POSITION:
19.6 N, 51.3 W. MOVEMENT TOWARD WEST-NORTHWEST NEAR 15 MPH. MAXIMUM
SUSTAINED WINDS, 90 MPH. MINIMUM CENTRAL PRESSURE, 994 MB.
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT 5:00 PM
Atlantic Standard Time.
HURRICANE BERTHA DISCUSSION NUMBER 18
NWS TPC NATIONAL HURRICANE CENTER MIAMI FL AL022008
11:00 AM EDT MON JUL 07 2008
BERTHA'S SATELLITE PRESENTATION HAS BECOME MORE IMPRESSIVE DURING
THE LAST 6 HOURS WITH A DISTINCT EYE NOW APPARENT. THE INITIAL
INTENSITY IS INCREASED TO 80 KT IN LINE WITH THE CONSENSUS OF THE
VARIOUS SATELLITE ESTIMATES. IN THE SHORT-TERM, THERE ARE NO
APPARENT ENVIRONMENTAL FACTORS WHICH WOULD INHIBIT FURTHER
INTENSIFICATION TODAY AND THE OFFICIAL FORECAST NOW CALLS FOR
BERTHA TO BECOME A CATEGORY TWO HURRICANE. HOWEVER, THE INTENSITY
FORECAST BECOMES MORE UNCERTAIN BEYOND 36 HOURS AS THE GLOBAL
MODELS DISAGREE ON THE DETAILS OF THE DEVELOPMENT OF AN UPPER-LEVEL
TROUGH OVER THE WESTERN ATLANTIC. THE GFS FORECAST THE MOST
UNFAVORABLE ENVIRONMENT WITH BERTHA ESSENTIALLY RUNNING INTO THE
TROUGH. NOT SURPRISINGLY, THE SHIPS AND LGEM STATISTICAL
MODELS, WHICH INCLUDE ATMOSPHERIC INFORMATION FROM THE GFS, SHOW
CONSIDERABLE WEAKENING. MEANWHILE, THE UKMET, GFDL AND HWRF
MODELS SHOWS A MUCH MORE FAVORABLE ENVIRONMENT AND DELAY WEAKENING
UNTIL THE VERY END OF THE FORECAST PERIOD. THE OFFICIAL INTENSITY
FORECAST LEANS MORE TOWARDS THE HIGHER SHEAR SCENARIO INDICATED BY
THE GFS, BUT DOES NOT WEAKEN BERTHA AS FAST AS THE SHIPS AND LGEM
MODELS.
THERE HAS BEEN LITTLE CHANGE IN THE HURRICANE'S HEADING DURING THE
LAST 6 HOURS WITH THE INITIAL MOTION ESTIMATE ESSENTIALLY
UNCHANGED... 285/13. HOWEVER, BERTHA IS BEGINNING TO ENCOUNTER A
WEAKNESS IN THE SUBTROPICAL RIDGE WHICH SHOULD RESULT IN A GRADUAL
TURN TOWARDS THE NORTH AND A REDUCTION IN FORWARD SPEED. THE
MODELS GENERALLY AGREE ON THIS EVOLUTION, BUT THERE REMAINS SOME
SPREAD AMONGST THE MODELS ON WHAT LONGITUDE BERTHA WILL TURN NORTH.
WHILE THE DEGREE OF THE TURN HAS IMPORTANT IMPLICATIONS REGARDING
POTENTIAL IMPACTS TO BERMUDA, IT IS MUCH TO EARLY TO DETERMINE IF
BERTHA WILL ACTUALLY THREATEN THAT ISLAND. HOWEVER, INTERESTS IN
BERMUDA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. THE NEW
OFFICIAL FORECAST IS NUDGED SLIGHTLY EASTWARD TOWARD THE TRACK
MODEL CONSENSUS.
This information is provided as a public service from the
National Hurricane Center
http://www.nhc.noaa.gov
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