For a more recent update on hurricane bill, CLICK HERE
Hurricane Bill continues to behave itself. It has become very strong with the 5pm EDT Wed Advisory suggesting 135 mph maximum winds with gusts to 155 mph. The forecast calls for a further increase in strength. The current pressure of 947 mb can support winds up to 145 mph and it looks like the boys at the NHC are taking it up to that level. In that instance, gusts are forecast to be kicking up to 165 mph. I don’t think that there is another big tropical cyclone on the planet right now so this makes Hurricane Bill the most powerful force on the face of the earth. Total energy release of Hurricane Bill is a few hundred times the global electrical generating capacity. The atomic bombs dropped by the US in World War II were some 10-20 kilotons. Hurricane Bill is releasing an energy equivalent of a 10 megaton nuclear weapon every 20 minutes! That means that the energy release every 20 minutes with Bill is an order of magnatude higher than the the Hiroshima bomb because that was kilotons…thousands of tons…this is megatons..millions of tons. This is why it is foolish when people suggest we drop an atomic weapon into a hurricane to stop it. Bill is a giant heat engine and so adding a nuclear bomb may just add more heat and certainly would make nothing more than a radioactive hurricane.
Anyway, Bill has an outstanding structure, as one might expect with such a formidable storm. It’s over pretty warm water so there’s no problem there. What will probably happen is variance in the wind speed as it goes through eye-wall replacement cycles. Typically, an inner eyewall collapses and a new one forms. As that occurs the energy gets dispersed and so the inner core winds may fall off but the broad wind field is pretty strong. As the cycle completes, then the inner winds go back up to where they were. Hurricane Katrina was going through a eyewall replacement at landfall, which is why the max winds were only Cat 3 but the broad winds of over 100 mph stretched all the way to Mobile and the storm surge was consistent with a very strong Cat 5 hurricane.
A few days I ago I suggested that the problem down the road would probably be the strength of the ridge in the Atlantic. It has broken down some and Bill has curved. Tuesday at 5pm it was tracking to 290 degrees. On Wednesday at 5pm it was tracking at 305 degrees. So, the curve continues and it is missing the Caribbean Islands. The spaghetti models do an interesting thing which is that some take it into Maine while others take it to Nova Scotia and others farther east. The National Hurricane Center chooses a solution in the middle, which is Nova Scotia. I’m sure that alarmed some people as I did get a note from someone in Halifax. The storm is way way out and it is simply not possible to pinpoint a landfall. Bermuda will feel some effects. To what degree, I don’t know but even if Bermuda is 200 miles away from the center, this cat is so big and strong the island could expect pretty tough seas and also probably hurricane force winds. So, they better hope that they are more than 200 miles away.
The GFS wants Maine as does the latest Canadian Model that I saw. A cold front is expected to be through Louisville on Friday morning….that’s the issue..the mean trof is slow. But, the trof is also deep digging all the way down to the Dixie States. So, its a strong long wave trof which means that the southwesterly flow ahead of it will also probably be strong. All this means is that I would think that Bill will start increasing in forward speed by Thursday night or Friday. Its already moving about 20 mph and will really start to hoof. That may allow it to threaten the extreme NE US or the Canadian Maritimes. But, a strong southwesterly flow would also tend to start to rip it up. In fact, the satellite image indicates that some of the outflow is displaced to the north. Bill also will eventually be moving into cooler water. For this reason, you see in the National Hurricane Center Forecast Discussion that they weaken the hurricane from major status. I would expect a weakening hurricane at landfall, most likely in the Canadian Maritimes, though the seas off of New England may be enormous and Maine will need to watch out, though a landfall to the east of Maine will mean and off shore flow. I would expect that, due to the anticipated forward momentum and the fact its been a big bopper, the storm surge will be higher than normal for a storm of Bill’s stature, whatever it is when landfall occurs…provided of course that it makes landfall, which I think it will be tough not to do…especially with that mass at that forward momentum. It can’t stop and turn on a dime.
WTNT43 KNHC 192031
HURRICANE BILL DISCUSSION NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
500 PM AST WED AUG 19 2009
VISIBLE SATELLITE IMAGES SHOW THAT BILL IS AN IMPRESSIVE HURRICANE
WITH MESOCYCLONES NOTED IN THE EYE…CURVED BANDING FEATURES IN ALL
QUADRANTS AND A WELL-ESTABLISHED OUTFLOW PATTERN. AN FORCE RESERVE
HURRICANE HUNTER RECENTLY MEASURED 135 KT AT 700 MB…ALONG WITH
SFMR WINDS OF 103 KT AND A MINIMUM PRESSURE OF 947 MB. IN
ADDITION…THERE WAS AN SFMR MEASUREMENT OF 106 KT FROM THE NOAA
MISSION THIS MORNING. SATELLITE CLASSIFICATION ARE 127 KT FROM
TAFB/SAB AND THE INITIAL INTENSITY IS KEPT AT 115 KT AS A
COMPROMISE OF ALL THESE DATA.
VERY WARM WATERS ARE ALONG THE PATH OF THE HURRICANE FOR THE NEXT
FEW DAYS. THE BIGGEST QUESTION IS WHETHER THE UPPER ENVIRONMENT
WILL REMAIN FAVORABLE FOR STRENGTHENING. A PAIR OF UPPER-LEVEL
TROUGHS HAVE THE POTENTIAL TO INDUCE SOME SHEAR ON BILL…ONE ALONG
60W AND OTHER AT ABOUT 70W. WHILE THE MODELS DISAGREE ON WHETHER
THE FIRST TROUGH WILL AFFECT THE HURRICANE MUCH…MOST MODELS SHOW
SOUTHWESTERLY SHEAR INCREASING IN A COUPLE DAYS AS A RESULT OF THE
SECOND FEATURE. IN ADDITION…AN EYEWALL REPLACEMENT CYCLE COULD
OCCUR AT ANY TIME WITH A SECONDARY WIND MAXIMUM NOTED AT ABOUT 75 N
MI FROM THE CENTER IN AIRCRAFT DATA. REGARDLESS…ALL OF THE
RELIABLE MODELS KEEP THE HURRICANE QUITE STRONG FOR THE NEXT
SEVERAL DAYS…AND THE OFFICIAL INTENSITY FORECAST REFLECTS THAT
THE ESTIMATED MOTION IS A LITTLE MORE TO THE RIGHT AND FASTER…NOW
305/17. STRONG SUBTROPICAL RIDGING SHOULD KEEP BILL ON THIS
GENERAL TRACK FOR THE NEXT COUPLE OF DAYS WITH A GRADUAL BEND TOWARD
THE NORTH-NORTHWEST BY THE WEEKEND AS THE HURRICANE MOVES INTO A
BREAK IN THE RIDGE. SOME OF THE MODELS…SUCH AS THE GFS…NOW
SHOW A SLIGHTLY STRONGER RIDGE OVER THE WESTERN ATLANTIC AND A
SLOWER MID-LATITUDE TROUGH MOVING ACROSS THE EASTERN UNITED STATES.
IF THIS SOLUTION IS CORRECT…BILL WOULD BE ABLE TO MOVE A LITTLE
FARTHER TO THE WEST BEFORE TURNING TO THE NORTH AND NORTHEAST.
THERE HAS BEEN A SMALL WESTWARD SHIFT IN MOST OF THE AFTERNOON
MODEL GUIDANCE…AND THE OFFICIAL FORECAST IS SHIFTED IN THAT
DIRECTION. THIS IS A GOOD TIME TO POINT OUT THAT THERE IS A LOT OF
UNCERTAINTY IN THE LONG-RANGE TROPICAL CYCLONE FORECAST AND ONE
SHOULD NOT FOCUS ON THE EXACT TRACK AT THOSE TIME PERIODS.
BECAUSE BILL IS A LARGE AND STRONG HURRICANE…SWELLS TRIGGERED BY
THE HURRICANE SHOULD AFFECT THE NORTHERN LEEWARD ISLANDS…THE
BAHAMAS…BERMUDA AND MOST OF THE EASTERN UNITED STATES DURING
THE NEXT FEW DAYS. THESE SWELLS WILL LIKELY CAUSE EXTREMELY
DANGEROUS SURF AND LIFE-THREATENING RIP CURRENTS. PLEASE CONSULT
STATEMENTS ISSUED BY YOUR LOCAL WEATHER OFFICE FOR MORE DETAILS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 19/2100Z 19.8N 57.6W 115 KT
12HR VT 20/0600Z 21.1N 59.7W 120 KT
24HR VT 20/1800Z 23.0N 62.4W 125 KT
36HR VT 21/0600Z 25.2N 64.6W 120 KT
48HR VT 21/1800Z 27.9N 66.6W 120 KT
72HR VT 22/1800Z 34.0N 69.0W 110 KT
96HR VT 23/1800Z 42.0N 65.5W 95 KT
120HR VT 24/1800Z 51.5N 50.5W 55 KT…EXTRATROPICAL