Hurricane Bertha (Was category-3)

[Iceberg]

Scrub some of the above latest visuals show the eye nice and clearly.

This is indeed a hurricane.!

Edited July 7, 2008 by Iceberg

[Iceberg]

And officailly we have Hurricane Bertha a CAT 1 at 65Kt.

IN THE HOURS LEADING UP TO 00Z...SEVERAL CONSECUTIVE MICROWAVE

OVERPASSES OCCURRED ON ROUGHLY AN HOURLY BASIS...AND ALMOST MADE IT

SEEM LIKE WE WERE RECEIVING RADAR FIXES. THOSE IMAGES REVEALED A

WELL-DEFINED AND VERTICALLY-ALIGNED EYE FEATURE...AND MORE RECENTLY

AN IMAGE FROM AMSU TAKEN AT 0517Z ALSO DEPICTED AN EYE. THE

MICROWAVE EYE DIAMETER APPEARS TO BE ABOUT 15-20 N MI. GOES

INFRARED IMAGERY HAS INTERMITTENTLY EXHIBITED HINTS OF AN

EYE...ESPECIALLY AROUND 06Z WHEN SUBJECTIVE DVORAK INTENSITY

ESTIMATES FROM TAFB AND SAB WERE BOTH 65 KT. OBJECTIVE DVORAK

ESTIMATES REMAIN SLIGHTLY BELOW THE HURRICANE THRESHOLD...BUT GIVEN

THE MICROWAVE SIGNATURES THE SYSTEM IS UPGRADED TO A HURRICANE...

THE FIRST OF THE 2008 ATLANTIC SEASON...WITH AN INTENSITY OF 65 KT.

WHILE A HURRICANE DOES NOT FORM EVERY YEAR IN JULY IN THE ATLANTIC

BASIN...IT HAS CERTAINLY HAPPENED BEFORE...INCLUDING IN 1996 WHEN

ANOTHER HURRICANE BERTHA FORMED...COINCIDENTALLY ALSO ON JULY 7.

[Cookie]

earlier then expected I think!

[dallas]

Scrub some of the above latest visuals show the eye nice and clearly.

This is indeed a hurricane.!

officially a hurricane now from NOAA

[Gray-Wolf]

First of the season and already something you could class as a cape Verde hurricane. I thought the Cape Verde's waited until late Aug/Early sept to put in an appearance?

The 'wave' that she is riding on is pretty well defined, I wonder if it'll take her further west before she does her northerly swing?

Will Big Bertha make land?

[kold weather]

Yep to be honest I'm not all surprised I fully expected a hurricane by now last night, eye popped up in IR and given the way it looked last night on Microwave with a fully closed bank of convection (eyewall) and a clear eye it was only a matter of time before that presentation showed itself better on IR.

USA mainland looking less likely to get hit now but the threat has to switch to Bermuda, for the sake of that island a slightly further west track would be a good thing for the island.

Gray-wolf, this is very early for Cape Verde but indeed it is a CV hurricane. ironically Bertha in 1996 was also a very early Cape Verde system in early July...and got upgraded to hurricane on the 7th of July 1996!

Edited July 7, 2008 by kold weather

[Iceberg]

Bertha is continuing to intensify quite rapidly IMO.

The main inflow channel is getting better and better and the outflow is still very good.

The eye has consolidated and pressure will likely be falling quite rapidly as it can't leak.

Still very good banding.

This is probably a CAT 2 IMO or not far off now. Dvorak has increase to 4.5 which equates to around 75-80Kt with sub 980 pressure. If it continues the next advisory at 4.00pm BST should have it as an 85KT CAT 2.

Visuals show Bertha to be rather an impressive little hurricane now.

[Iceberg]

Models did not initialise very well at 06Z, Meto sends it further westward again, GFS failed to initialise Bertha at start up so should be completely discounted.

GFDL started Bertha at 75Kt which seems reasonable and takes her above 100Kt to the east of Bermuda.

HWRF didn't capture the start up well and doesnt look at all right.

[Iceberg]

Bertha has been classified as 5Kt short of a CAT 2, so significant strengthening has occured.

The track which I've attached does not look good for Bermuda. I'd expect them to increase intensity over the longer term as I don't believe GFS initialised it correctly to begin with.

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.

[Iceberg]

WOW !!!!

Now a boarderline CAT 3.

Dvorak has gone up to a 5 (90 KTS 104 MPH 970 mb). Since then Bertha has improved even more.

She will certainly be upgrade to a CAT 2 and maybe a CAT 3.

Sat is very impressive (better than some Major's I've seen!).

Path is slightly north of predicted.

[tinybill]

http://www.nhc.noaa.gov/graphics_at2.shtml?5day#contents

looks like Bermuda going to get a direct hit now

[Iceberg]

For confirmation Ships initialised at 90Kt at 19.00 BST.

METO has it staying as a Major for most of it's forecast period.

GFDL initialised it as Nearly 100Kt and takes it to CAT 4.

GFS 12Z brings about the prospect of Bertha almost stopping over Bermuda......

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE BERTHA (AL022008) 20080707 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

080707 1800 080708 0600 080708 1800 080709 0600

LAT LON LAT LON LAT LON LAT LON

BAMS 19.9N 51.6W 20.6N 54.3W 21.4N 56.5W 21.7N 58.3W

BAMD 19.9N 51.6W 20.8N 53.3W 21.6N 54.7W 22.3N 56.1W

BAMM 19.9N 51.6W 20.6N 53.6W 21.3N 55.3W 21.8N 56.8W

LBAR 19.9N 51.6W 20.7N 53.5W 21.8N 55.4W 22.6N 57.2W

SHIP 90KTS 94KTS 92KTS 88KTS

DSHP 90KTS 94KTS 92KTS 88KTS

A couple more pic(Sorry if this bores anyone! )

Close of a truely impressive eye and the storm as just taken.

The lack of shear and good banding are really making Bertha good looking.

[Katherine]

GFDL initialised it as Nearly 100Kt and takes it to CAT 4.

STREWTH!

[kold weather]

Thats higher then 90kts I'm certain of that, raw Dvorak now at 5.9 which is around category-4 strength already. Cracking presentation with a nearly totally clear eye, perfect CDO. Convection isn't very deep and thats the only thing that may be holding it back a little but right now I'd put that it at 100kts easily, probably more like 105-110kts IMO.

Very impressive hurricane thats for sure, esp given we are only in early July and we have a hurricane this far east in the Atlantic, these really are rare beasts...

[Iceberg]

It's certainly still tightening I'd probably go for 955 and around 100Kt. The one draw back is the still 27C SST underneath. I wouldn't have thought this could support a CAT 4 ?. Must admit Bertha's structure is near perfect though. A futher 12-24 hrs of strengthening to come before a slight calm.

[kold weather]

Hmmm it all depends on upper conditions to be honest, 27.5C probably could support cat-4 in decent conditions. Eye has contracted a little recently whilst the structure still looks good. Eye probably needs to warm a little so I think my earlier guess is a little extreme, probably 95-100kts is more reasonable now looking at the structure.

[kold weather]

Rapid strengthening has occured with Bertha today, now offically a category-3 major hurricane!!!

...Bertha strengthen to a major hurricane with 115 mph winds...

at 500 PM AST...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 500 PM AST 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

1100 PM AST.

$$

Forecaster Rhome

[Somerset Squall]

Wow! I didn't expect this! As the NHC says, Bertha's unforseen rapid intensification really shows how difficult forecasting future intensity of tropical cyclones is. Looks very impressive- How high will Bertha go?

Latest image:

[Mesosphere]

, god almighty bertha has exploded in intensity in the last 24 hours , this time last night , when i last looked at the thread , it was a Tropical Storm it's now a CAT 3 HURRICANE!

[kold weather]

Shows just what favorable upper conditions and even fairly low heat content can do to a storm, it was clear this could become a powerful system this morning when that tight eye formed. Sat.estimates have the central pressures down to 948mbs which is very low for a 100kt hurricane, if thats the case expecxt the winds to increase eventually to 110-115kts as they catch up with that pressure and the eye continues to tighten.

Still this is real rare stuff here, indeed historical!

[Cookie]

wow kinda speechless here. wasn't expecting this!

so where is it most likely to hit at the moment?

[Iceberg]

ESTIMATED MINIMUM CENTRAL PRESSURE 952 MB

EYE DIAMETER 15 NM

MAX SUSTAINED WINDS 105 KT WITH GUSTS TO 130 KT.

Bertha is struggling this morning, interesting that they say she might have made a CAT 4 yesterday at some point.

Her size is strinking, along with relatively warm cloud tops etc the eye looks like it might be in difficulty.

Quickly up/Quickly down is the saying and this could be true with Bertha. She still has good banding but not very much of it and pressure will leak very quickly.

All good news for Bermuda though(although the path has now shifted eastwards again and it seems unlikely Bermuda will be hit.

The next thing to watch will be the re-curve to this country.!

[opplevelse]

GRrrrr stupid bloody forum image rules wont allow me to directly link :mad:

Most recent track map

Track certainty is increasing (see comments below) but she will be moving into an area of high shear (40-50kts) which will weaken and eventually destroy her.

Wind shear (click for larger)

Stearing forecast notes

ON THE OTHER HAND...THE TRACK FORECAST HAS BECOME A LITTLE MORE

CERTAIN SINCE THE TRACK MODELS ARE IN BETTER AGREEMENT AND THE

GUIDANCE ENVELOPE IS SMALLER. BERTHA IS MOVING TOWARD THE

WEST-NORTHWEST OR 300 DEGREES AT 10 KNOTS WHILE APPROACHING A

WEAKNESS IN THE SUBTROPICAL RIDGE. THE RIDGE IS EXPECTED TO

REBUILD SOME AND THIS PATTERN WOULD FAVOR A CONTINUATION OF THE

WEST-NORTHWEST TRACK FOR A DAY OR TWO....FOLLOWED BY A GRADUAL TURN

TO THE NORTHWEST AND NORTH. BY DAYS 4 AND 5 THE STEERING CURRENTS

ARE FORECAST TO COLLAPSE AND BERTHA WILL PROBABLY MEANDER FOR A

LITTLE BIT.

A little storm to start to the season

[opplevelse]

BTW There is a Terra MODIS shot due for 14:05 today, which should be smack bang over Bertha, will provide a good view. will put it up when it is uploaded.

[Iceberg]

Kept as a Sev 3 to be honest Bertha is looking worse by the hour. Shear is taking it's toll and as she has strunk she's still struggling to cope with it. Warmer SST's are not firing off any deeper convection that might help.

Cat 2 atm IMO and if the eye is exposed a weak CAT 1 soon.

THE EYE OF THE HURRICANE HAS BECOME A LITTLE LESS DISTINCT OVER THE

PAST SEVERAL HOURS. NONETHELESS...BERTHA HAS BEEN MAINTAINING A

FAIRLY SYMMETRICAL RING OF COLD CLOUD TOPS AROUND THE CENTER.

SUBJECTIVE AND OBJECTIVE DVORAK T-NUMBERS HAVE COME DOWN SLIGHTLY

BUT CURRENT INTENSITY ESTIMATES...BOTH OBJECTIVE AND SUBJECTIVE...

REMAIN CLOSE TO 105 KT. HENCE THE ADVISORY INTENSITY IS UNCHANGED.

SOME FLUCTUATIONS IN STRENGTH ASSOCIATED WITH EYEWALL REPLACEMENTS

COULD OCCUR WITHIN THE NEXT 12 HOURS OR SO. IN THE LONGER-TERM...

THE ENVIRONMENT IS EXPECTED TO GRADUALLY BECOME LESS CONDUCIVE FOR

STRENGTHENING AS BERTHA MOVES TOWARDS HIGHER LATITUDES. THIS IS

REFLECTED IN THE SHIPS MODEL...WHICH WEAKENS BERTHA TO MINIMAL

HURRICANE STRENGTH BY 72 HOURS. THE OFFICIAL INTENSITY FORECAST

CLOSELY FOLLOWS THE INTENSITY MODEL CONSENSUS ICON.

BTW morning opplevelse, lets hope there is something for Modis to capture.