cieldumort
Moderator
Reged: Mon
Posts: 2305
Loc: Austin, Tx
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IR can be so deceptive. It now looks more like there were just some spacial artifacts created when Bertha blew up some additional convection and blew off some tops, earlier.
With the aid of an AMSRE composite from 0521Z, and pairing that with what looks to be some deep convection making a partial ring, I'm betting that a nearly northwest motion is right on target. 5AM discussion out of shows that they are certainly going with this.
As for initial intensity as well as thermal structure, right now it appears that the HWRF is about the only model that is close to spot-on, and it also indicates an entirely believable re-intensification.. to at least a solid Cat 2 (and given this cyclone's history, Cat 3/4 looks to be entirely back in the realm of the very possible). The ULL to her west continues moving even farther away from her, and on her current heading, shear is relaxing, and outflow improving.
If Bertha does indeed spend at least the next five to seven days in the western Atlantic fluctuating in intensity between Cat 1 and major hurricane, she'll have added one heck of a sizable number to this season's ACE. This would simply be an amazing feat for an early season tropical cyclone, and something we haven't seen since 2005.
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SATBEACH
Unregistered
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If Bertha continues on it's current track for the day, they may adjust the track back to the left a bit.
Certainly would mean more problems for Bermuda.
http://www.ssd.noaa.gov/goes/east/catl/loop-vis.html
Looks like it is skirting along 24N
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ftlaudbob
Storm Chaser
Reged: Tue
Posts: 828
Loc: Valladolid,Mx
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Looks like she is trying to form an eye again also.No question she is moving more west now.This was also just reported on the local news here.
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Survived: 10 hurricanes in Rhode Island,Florida and the Yucatan of Mexico .
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typhoon_tip
Meteorologist
Reged: Wed
Posts: 576
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The 11am advisory still has a 300degree motion associated with Bertha.
It appears irregular convective prominences are causing "wobbling" of the track. These wobbles can often take as much as 3 or 4 hours to unfold. It is perhaps too easy in those intervals of time to believe something unexpected is taking place. But, I am not seeing a big enough deviation between her apparent axis of circulation to that of the clear NW track motion provided by the TPC - they seem to be aligning just fine. Moreover, there isn't really much compelling synoptic reason that asserts Bertha should be resuming a west motion, for the time being. Steering field remains weak, but with a trough "denting" the Bermuda ridge as it presses off-shore the NE U.S. over the next day and half, if anything this offers at least a small argument for continue northwest or perhaps even eventually a north motion...albeit slowly. Speed of motion does not appear to have any means to really accelerate until perhaps very late in the 5-day forecast period.
What I am seeing in recent guidance is a clear emerged consensus that the next trough (4+days) will be a bit more substantial. The Euro model, for example, uses that trough to pick up Bertha and deliver her to the graveyard. Other models including the UKMET (also, 00Z run), run Bertha up the eastern flanks of the baroclinic wall associated with the same trough. The Canadian model is the slowest with this overall evolution but still argues for the same sort of thing...stronger trough nearing D5 sets up a baroclinic axis off-shore and this veers the steering field more discernibly toward the graveyard and an alas re-curve scenario finally takes place there after.
It is possible that after this first trough (D1-D3) leaves the NW Atlantic, the ridge may respond a bit more robustly than currently modeled. If that were the case, than said deeper trough D4-6 may find an axis more west of currently depicted. That offers some envelope of discussion for gaining more longitude - perhaps - than currently suggested. There has been a seasonal bias in the models to try and dampen the west-central Atlantic ridge too much. Just something to keep and eye out for, as this would offer a greater degree of threat to Bermuda.
By and large, the greater synoptic challenge to preventing Bertha from re-curving has been answered for in my mind. Over the next week and beyond, it seems troughs passing from the GL-NE U.S. at higher/middle latitudes will pretty much seal a fate that will ultimately force Bertha seaward. Simply a matter of when. It is probably...actually...that what we are seeing is a step-wise escape to higher latitudes. First a weakness in the ridge instantiated a NW motion over the last day.5; that weakness fills and Bertha slows down and wobbles; then another weakness associated with a trough passing NW of Bermuda over the next two days may focus more NW motion; she slows again as said trough leaves the area; then we await a deeper trough expression in the extended to put the final hammer head down of that coffin nail. This seems the most likely pattern of behavior for Bertha's future to me.
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Rich B
British Meteorologist
Reged: Sat
Posts: 498
Loc: Gloucestershire, England, UK
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Visible imagery shows Bertha becoming somewhat better organised, and available imagery from also shows the eye becoming much better defined. Appears that the reorganising episode is also having an effect on motion, with some wobbles of the eye during the past 3 hours. Interesting that the models have shifted back to the west a little on the forecast track too... certainly one for Bermuda to keep an eye on!
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Rich B
SkyWarn UK
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danielw
Moderator
Reged: Wed
Posts: 3525
Loc: Hattiesburg,MS (31.3N 89.3W)
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Excerpt from yesterday's:
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
201 PM EDT TUE JUL 08 2008
AT 500 HPA...AN ANTICYCLONE NORTH OF THE ISLANDS... CENTERED NEAR
33N 66W AT 24 HRS ENVELOPS THE AREA NORTH OF THE GREATER ANTILLES.
THROUGH 24-36 HRS THE RIDGE BECOMES NARROW AND ELONGATED EAST TO
WEST AS SHORT WAVE PERTURBATIONS EJECTING ACROSS THE EASTERN USA
THEN LIFTING OVER THIS RIDGE WILL ERODE THIS AXIS FROM THE NORTH.
BY 60-72 HRS THE ANTICYCLONE WILL BE CENTERED OVER THE NORTHERN
GULF OF MEXICO WITH A RIDGE AXIS EAST SOUTHEAST ACROSS THE
SOUTHERN BAHAMAS. A SECOND CELL OF THE SUBTROPICAL RIDGE LIES
FARTHER EAST... WITH A RIDGE EXTENDING WEST FROM AFRICA ALONG 20N
EAST OF 50W. THIS RIDGE PERSIST OVER THE TROPICAL ATLANTIC.
HURRICANE BERTHA LIES BETWEEN THESE RIDGES.
edit~ be extremly careful whern using the storm headings. They are averaged over a 6 to 12 hour span and can be very misleading.
Remember of 2004. Headings were just west of due North,toward the NNW and was making a perfect right turn into Punta Gorda,FL. ~danielw
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typhoon_tip
Meteorologist
Reged: Wed
Posts: 576
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Recent satellite images offering numbers much stronger than the 11am advisory of 65kts, already... It may simply be that a more rapid period of intensification is taking place but the wind field has simply not yet responded. Recent looping IR, WV, and Visual imagery all suggest robust intensification under way.
Additionally, the upper air wind overlays show a bit of outflow jet developing on the NW quadrant, toward Bertha's direction of motion. As well...over all, the subtle semblances of light shear appear to have been replaced by more symmetric outflow in general. This combined with amply warm water, there really isn't any compelling reason to argue against intensification overall; but more importantly, the repeatedly learned lesson is that when hurricanes are given a lease on life like that they tend to exercise that right at least excuse imaginable...and go on ahead to "surprising" everyone for how they did this and that in "such a short period of time".
We'll see...
John
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danielw
Moderator
Reged: Wed
Posts: 3525
Loc: Hattiesburg,MS (31.3N 89.3W)
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The Position History For Hurricane Bertha (2008) can be found on this page here:
http://flhurricane.com/cyclone/stormhistory.php?storm=2&year=2008
It gives compass headings, rather than degree headings.
Bottom half of the Latest Discussion on Bertha. Models are having a rough time beyond 72 hours.
HURRICANE BERTHA DISCUSSION NUMBER 26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
1100 AM EDT WED JUL 09 2008 (edited~danielw)
...THE INITIAL MOTION IS ESSENTIALLY UNCHANGED FROM THE PREVIOUS
PACKAGE...300/10.
BERTHA SHOULD CONTINUE A SLOW TURN NORTHWARD
DURING THE NEXT 2-3 DAYS AS A MID-TROPOSPHERIC ANTICYCLONE
CURRENTLY NEAR BERMUDA IS FORECAST TO WEAKEN AND A 500 MB
SHORTWAVE TROUGH MOVES OFF OF THE U.S. EAST COAST.
BEYOND 72
HOURS...THE TRACK BECOMES A LITTLE LESS CERTAIN AS THE SHORTWAVE IS
NOT CURRENTLY FORECAST TO PICK UP THE CYCLONE.
RATHER...IT LEAVES
BERTHA BEHIND IN WEAK STEERING CURRENTS POSSIBLY RESULTING IN SLOW
AND ERRATIC MOTION AT THE END OF THE FORECAST.
TRACK MODELS HAVE
NOT DEMONSTRATED GOOD RUN TO RUN CONSISTENCY.
AS A RESULT...THE
NEW OFFICIAL TRACK FORECAST IS ESSENTIALLY UNCHANGED AND LIES WEST
OF THE DYNAMICAL MODEL CONSENSUS.
IT IS STILL TOO EARLY TO KNOW WHETHER BERTHA WILL HAVE AN IMPACT ON
BERMUDA. INTERESTS ON THAT ISLAND SHOULD CONTINUE TO MONITOR THE
PROGRESS OF THIS HURRICANE OVER THE NEXT COUPLE OF DAYS.
http://www.nhc.noaa.gov/text/refresh/MIATCDAT2+shtml/091440.shtml
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cieldumort
Moderator
Reged: Mon
Posts: 2305
Loc: Austin, Tx
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Outflow continues improving this afternoon, after some improvement during the late overnight and into the morning hours, as well. Deep convection now encircles a well-defined, fairly smooth and symmetric eye. Perhaps a little bit of interruption to the outflow channel that has been such a boon to her exhaust the past couple of days, but nothing perilous to her health just yet.
Now that CIMSS has got her position right again, and just in time for this most recent upswing in intensity, ADT is playing a little catch-up, with the CI still only reading 4.4 (garbage in, garbage out), but with an easily far more accurate adjusted T of 5.4, for around 100 knots.
With SAB already running 5.0 (around 90 knots) a little over an hour and a half ago, should the current trends persist for just a little while longer, there may easily be a 5PM advisory showing Bertha back up as a major.
Track continues just a hair to the *right* of OFCI. Wobbles along her path, and also the occasional clutter produced by some convective flare-ups, may have been making this appear less so from time to time. But once 3, 6 and 12 hour time-frames go by, the nearly nw trend stays very much intact.
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Rich B
British Meteorologist
Reged: Sat
Posts: 498
Loc: Gloucestershire, England, UK
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Expect Bertha to be a lot stronger at the 2100z advisory cycle - TNumbers at 1745z this evening were T5.0/5.0 from SSD - corresponding to near 105mph. The satellite presentation has continued to improve since then so it could well be higher. Certainly looks possible that Bertha may be undergoing rapid intensification.
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Rich B
SkyWarn UK
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JoshuaK
Weather Guru
Reged: Mon
Posts: 159
Loc: Lakeland, FL
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The official forecast called for Intesificaton up to 80 knots or 90 mph, but I think Bertha has easily beat that for the 5PM advisory. I'm betting she's up to at least 100mph winds again, maybe even Cat 3 status again. Very impressive looking on satellite imagery right now.
I don't suppose Hurricane Hunters can be based out of Bermuda?
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neospaceblue
Weather Watcher
.gif)
Reged: Thu
Posts: 28
Loc: Newport News, VA
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New advisory in has this up to Category 2 with the possibility of regaining Category 3. The forecast has it reaching Cat. 3 in 12 hours and weakening back into a Category 2 in 36 hours. Honestly, I wouldn't be surprised now, if Bertha reached Category 4 with this statement:
Quote:
BERTHA IS FORECAST TO BE IN A
SEEMINGLY FAVORABLE ENVIRONMENT FOR THE NEXT DAY OR SO AND
CONTINUED STRENGTHENING IS EXPECTED IN THE SHORT-TERM.
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I survived: Hurricane Bonnie (1998), Hurricane Dennis (1999), Hurricane Floyd (1999), Hurricane Isabel (2003), Tropical Storm Ernesto (2006)
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Storm Cooper
User
Reged: Sat
Posts: 1290
Loc: Panama City , FL
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Bertha remains a tricky system to say the least.... a part of the 5am Discussion...
BERTHA'S FORWARD MOTION HAS SLOWED A BIT AND IS NOW ABOUT 315/8. AN
ANTICYCLONE TO THE NORTH OF THE HURRICANE WILL CONTINUE TO SLIDE
EASTWARD OVER THE NEXT DAY OR ...SO THE TRACK OF THE HURRICANE
IS LIKELY TO BEND TOWARD THE NORTH THROUGH 48 HOURS. BEYOND THAT
TIME...THE TRACK FORECAST IS COMPLICATED BY THE FACT THAT THE
DYNAMICAL MODELS...IN PARTICULAR THE ...SHOW A MID-LEVEL
ANTICYCLONE DEVELOPING TO THE NORTH OF BERTHA IN AROUND 72 HOURS.
THIS DEVELOPMENT WOULD AT LEAST RETARD THE NORTHWARD PROGRESS OF
THE HURRICANE AND...IF THE ANTICYCLONE TURNS OUT TO BE STRONG
ENOUGH...COULD EVEN FORCE A TURN TO THE LEFT AS INDICATED BY THE
GFS. THE AND HWRF MODELS RESPOND TO THE INCREASED RIDGING
MAINLY BY SLOWING THE TROPICAL CYCLONE AS IT CROSSES 30N LATITUDE.
IT IS CERTAINLY POSSIBLE FOR BERTHA TO MOVE ERRATICALLY IN ABOUT 3
DAYS...BUT THE DETAILS OF THAT MOTION ARE OF COURSE UNKNOWN.
Edited by Ed Dunham (Thu Jul 10 2008 07:41 AM)
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danielw
Moderator
Reged: Wed
Posts: 3525
Loc: Hattiesburg,MS (31.3N 89.3W)
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Current SHIPS Forecast is from 12Z.
At the 72 hour mark it is indicating Bertha should go no further west than the 31.1N/ 62.0W area. Bertha should begin to recurve from that point based on the latest SHIPS run.
The other four main Tropical Models 72 hour position from the 12Z run.
BAMS__29.3N 62.2W
BAMD__32.7N 64.6W
BAMM__30.7N 63.3W
LBAR__31.5N 61.2W
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Treymont
Unregistered
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What is that off the coast of SC? It's in warm water and it looks like there is some slight circulation. Could tjis be a factor that could steer Bertha?
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typhoon_tip
Meteorologist
Reged: Wed
Posts: 576
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Quote:
What is that off the coast of SC? It's in warm water and it looks like there is some slight circulation. Could tjis be a factor that could steer Bertha?
Not at this time. If it were to somehow develop, and do so substantially, then we could consider it, but for now it is a decaying linear MCS (squall line). A cold front is pressing seaward from off the mid Atlantic and New England coasts and the activity you are noticing is associated.
I am not seeing any curl in the region, at this hour. However, fronts can be tricky, particularly as they tend to stall in the northern Gulf of Mexico, or off the southeast U.S. coast. When they do, the upper air support eventually weakens...the air masses on either side of the boundary homogenizes. The convergence along the frontal zone its self, however, lingers a bit longer and this can sometimes lead to the development of TCs.
That is not occurring at this time; and would need to, and do so significantly, before it could become an influence on Bertha. However, since a front is in fact slipping into that area, it doesn't hurt to monitor.
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Ed in Va
Weather Master
Reged: Fri
Posts: 489
Loc:
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Hmmm...the most recent shows Bertha essentially stalled due east of NC 7 days from now. Anyone with thoughts on that?
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Survived Carol and Edna '54 in Maine. Guess this kind of dates me!
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typhoon_tip
Meteorologist
Reged: Wed
Posts: 576
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Not beyond the realm of possibilities, actually...
There is always an element of uncertainty with TCs, in particular because of the unknowns in how they will interact with the surrounding atmospheric medium. In this situation, we have cyclic trough and ridge occurrence taking place in the general regions NW-N-NE of Bertha's current direction of motion. We can assess from common wisdom that troughs will tend to excite a northward/northeast motion, but ridges will stunt that and/or even resume west motions. The problem is, there's a spectrum of possibilities in how they will effect Bertha's track (and to some extent intensity) between these two plausibilities, which depends entirely on correctly modeling the strengths and timings of the synoptics as described.
Not an easy task, particularly when subtle permutations can lead to unexpected track shifts, few of which can be correctly assessed beyond a few days time.
In general though, the 12Z is not really that off the going thinking as of 11am. The official call is a general NW or even N motion that will be slow, and then a potentially stall 3 days from now. This is essentially what the is indicating as far as I can tell. The question in this run is what takes place beyond D4... It seems the is trying to lesson the latitudes in which that next trough digs off the east coast, and that is why in this run we don't see as much acceleration toward the graveyard as the other runs/models have intimated.
Edited by typhoon_tip (Thu Jul 10 2008 02:02 PM)
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Treymont
Unregistered
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After looking at this satalite image,
http://www.ssd.noaa.gov/goes/east/tatl/loop-wv.html
I wonder if the fromt coming off the east coast will push Bertha a little south, and then Bertha will shift North and affect Bermuda (hopefully not).
Does anyone else see this?
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Treymont
Unregistered
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Found this posting on another board..the pic posted makes me wonderabout Bertha's path....
http://members.boardhost.com/hurricanecity/msg/1215709827.html
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