Hurricane Bertha Advisory 19, Storm Intensifies Into A Major Hurricane

BULLETIN
HURRICANE BERTHA ADVISORY NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
5:00 PM ATLANTIC STANDARD TIME MON JUL 07 2008
BERTHA STRENGTHENS TO A MAJOR HURRICANE WITH 115 MPH WINDS...
AT 5:00 PMATLANTIC STANDARD TIME, 2100Z, THE CENTER OF HURRICANE BERTHA WAS
LOCATED
NEAR LATITUDE 20.1 NORTH...LONGITUDE 52.1 WEST OR ABOUT 730 MILES...
1175 KM EAST-NORTHEAST OF THE NORTHERN LEEWARD ISLANDS AND ABOUT
1150 MILES, 1855 KM SOUTHEAST OF BERMUDA.
BERTHA IS MOVING TOWARD THE WEST-NORTHWEST NEAR 12 MPH, 19 KM/HR.
A GRADUAL TURN TOWARD THE NORTHWEST WITH A DECREASE IN FORWARD SPEED
IS EXPECTED OVER THE NEXT COUPLE OF DAYS.
MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 115 MPH, 185 KM/HR, WITH
HIGHER GUSTS. BERTHA IS NOW A CATEGORY THREE HURRICANE
ON THE SAFFIR-SIMPSON HURRICANE SCALE. FLUCTUATIONS IN INTENSITY
ARE LIKELY DURING THE NEXT DAY OR TWO.
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 948 MB, 27.99 INCHES.
REPEATING THE 5:00 PM ATLANTIC STANDARD TIME POSITION:
20.1 N, 52.1 W. MOVEMENT TOWARD WEST-NORTHWEST NEAR 12 MPH. MAXIMUM
SUSTAINED WINDS 115 MPH. MINIMUM CENTRAL PRESSURE, 948 MB.
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT 11:00
PM ATLANTIC STANDARD TIME.
HURRICANE BERTHA DISCUSSION NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
5:00 PM EDT MON JUL 07 2008
BERTHA'S SATELLITE PRESENTATION HAS CONTINUED TO IMPROVE THIS
AFTERNOON WITH A VERY DISTINCT EYE NOW SURROUNDED BY A RING OF COLD
CLOUD TOPS. SUBJECTIVE DVORAK T NUMBERS WERE UNANIMOUSLY 5.0 BUT
OBJECTIVE NUMBERS HAVE INCREASED TO 6.0 FOR THE PAST 3 HOURS. THIS
SUPPORTS AN INITIAL INTENSITY OF 100 KT MAKING BERTHA A MAJOR
CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON HURRICANE SCALE.
BERTHA'S INTENSIFICATION TO MAJOR HURRICANE TODAY HIGHLIGHTS THE
DIFFICULTIES OF FORECASTING RAPID INTENSITY CHANGES. IN THE
SHORT-TERM, SHEAR IS EXPECTED TO BE LOW AND THE INTENSITY WILL BE
PRIMARILY CONTROLLED BY EYE-WALL CYCLES. AS A RESULT, SOME
FLUCTUATIONS IN INTENSITY ARE LIKELY. IN A DAY OR TWO, THE GFS
MODEL STILL INDICATES INCREASING SHEAR. THE SHIPS AND LGEM
STATISTICAL MODELS, WHICH BASE THEIR SHEAR ESTIMATES FROM THE
GFS, SHOW WEAKENING BEYOND 24 HOURS AND SO DOES THE OFFICIAL
FORECAST.
BERTHA HAS BEEN MOVING MORE TOWARDS THE NORTHWEST DURING THE LAST
COUPLE OF HOURS WITH A REDUCTION IN FORWARD SPEED. BOTH INDICATIONS
THAT THE HURRICANE HAS REACHED THE MUCH-ANTICIPATED WEAKNESS IN THE
RIDGE. SINCE BERTHA COULD BE WOBBLING, THE INITIAL MOTION
ESTIMATE BASED ON A 12 HOUR AVERAGE IS 300/10. TRACK GUIDANCE
REMAINS IN GOOD AGREEMENT ON A GRADUAL NORTHWARD TURN DURING THE
NEXT 2-3 DAYS. THEREAFTER, GLOBAL MODELS SUGGEST THAT THE
STEERING CURRENTS COULD BECOME WEAK LEADING TO INCREASED UNCERTAINTY
IN THE TRACK FORECAST. EVEN THOUGH THE OFFICIAL FORECAST IS
SHIFTED A LITTLE TO THE EAST, IT IS STILL WAY TOO SOON TO
DETERMINE WHETHER OR NOT BERTHA WILL AFFECT BERMUDA.
This information is provided as a public service from the
National Hurricane Center
http://www.nhc.noaa.gov

or
http://hurricanes.gov