MikeCAdministrator
(Admin)
Wed Aug 19 2009 06:57 AM
Bill Could Brush Nova Scotia as a Cat I on Sunday

11AM EDT 22 Aug 2009 Update
Cat II Bill is now heading north and slowly weakening and with an anticipated turn to the northeast, Bill could brush Nova Scotia as a Cat I on Sunday. Environmental Canada has issued appropriate warnings. NHC has also issued a Tropical Storm Warning for eastern Massachusetts for this evening/tonight as follows:

"A TROPICAL STORM WARNING IS IN EFFECT FOR THE COAST OF MASSACHUSETTS
FROM WOODS HOLE TO SAGAMORE BEACH...INCLUDING THE ISLANDS OF
MARTHAS VINEYARD AND NANTUCKET."

During last night and through this morning the winds at Hamilton, Bermuda, have been steady at about 40mph with gusts to 55mph. Late yesterday evening, Commissioners Point reported a wind gust to 97mph.

The wave in the eastern Atlantic remains disorganized.
ED

5 PM EDT 21 Aug 2009 Update
Bill has weakened to a Category 2 hurricane, and is bringing winds and rain to Bermuda tonight. Bill is still in very good conditions for development and appears to be going through an eyewall replacement cycle, it could restrengthen again before hitting cooler waters.\

Bill is no longer expected to affect New England with winds, but Canada must remain watch. The possibility of recurving out to sea without landfall is also once again high.

In the east Atlantic we are watching a wave that has a <30% chance to develop over the next few days, no invest designation has been placed on this area as of yet.

4 PM EDT 20 Aug 2009 Update
A hurricane Watch is now up for the islands of Bermuda.

Bermuda Radar
Bermuda Weather Service Webcam Recording
Current Weather at Hamilton

8 AM EDT 20 Aug 2009 Update
Bill has weakened somewhat overnight, but is expected to restrengthen as shear lessens.

Tomorrow conditions are complex so it could gain or lose some strength depending on how much the trough interacts with it.

Most likely it will not landfall in New England, but it is by no means totally conifdent in that. The chances for landfall, although less, are still there.

The forecast track still keeps it offshore, but Cape Cod and parts of New England (Ie Boston/Cape Cod, northward) are going to be very close to it and need to watch it. Landfall in Canada still seems the most likely.


Today and Tomorrow may be stressful for those trying to determine what will happen, especially in the case of a large storm with the edge of the cone in your area, but most models are pulling it right quickly. Some, such as the GFS move it further west.

Original Update
Hurricane BIll strengthened into a category four hurricane overnight, with 135MPH winds. It may be a bit stronger than that, but determination will have to wait until another Aircraft recon gets there.

Bill likely will stay strong for the next two days until it begins to weaken.

All indicators are that Bill will stay offshore of the United States, with a small chance that it could affect extreme eastern portions of Massachusetts. Still, the most likely outcome is that it stays far enough out to sea that I think Bermuda should have more concern than that. The Eastern Canadian Provinces have a good chance, though, for a landfall from Bill. Although it should be weaker that it is now at that time, it still will be fairly strong. See the {{CHC}}



In short, New England needs to watch for Changes, Newfoundland in Canada really needs to pay attention, it could still be hurricane strength when it approaches there.

The remnants of Ana are beginning to affect Florida now with extra rain.

Outside of that, the last wave off Africa fell apart, but there is always a chance the next one could form. Outside of that, there is nothing else going on at the moment.

{{radarlink|byx|Key West Florida}}
{{radarlink|amx|Miami Florida}}
{{radarlink|mlb|Melbourne Florida}}
{{radarlink|tbw|Tampa Florida}}


{{StormLinks|Bill|03|3|2009|2|Bill}}


berserkr
(Verified CFHC User)
Wed Aug 19 2009 07:05 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

first reply first reply!!

this thang is gettin interestin now. it's the little thangs that count, and pull it all together to make sense of the big picture. i'm thankin Bill has a high probability to become a strong storm, perhaps a formidible hurricane to be dealt with. if it doesn't curve into the cone of certainty, people could be in trouble somewhere. thats about all i can say about Bill at the moment, but more to come later as i get a better feel for the storm. most likely i will update this post as time goes on so as not to confuse anyone. thanks for the hard work guys... you make my forecasting job a lot easier. two thumbs up, way to go!


LoisCane
(Veteran Storm Chaser)
Wed Aug 19 2009 10:27 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

I find it extremely quiet around here. With a Cat 4 storm heading northwest in the Atlantic, not far from the islands and the cone touching land on it's west side... not sure if there is an over reliance on models or what?

A Category 4 in the Atlantic after a somewhat dud season is to me exciting and always an educational experience.

And ... late August is tricky for a Cape Verde Storm ...this is not Sept 19th when they are a bit more predictable.

Just my thoughts.

http://www.ssd.noaa.gov/goes/east/nwatl/loop-wv.html

Dynamics very fluid and that new upper level low to the west of the old one is really digging...


Tropicbird
(Registered User)
Wed Aug 19 2009 11:00 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

I'm watching, especially since I'm supposed to start driving to Nova Scotia tomorrow and arrive by Aug 26.

Looking at the water vapor loop you posted Lois, why is he not going more north already? Although it looks like he is starting to gain latitude and heading towards the ULL to his N-NW. Maybe I don't know enough about how to read the WV, or about how hurricanes interact with ULL's.


TropicBird
(longtime lurker)


doug
(Weather Analyst)
Wed Aug 19 2009 12:19 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

movement to wnw. Lois, that is a very deep amplitude trough digging in to the west. No reason to believe that will erode. Bill is out to sea.
eds


Beach
(Weather Guru)
Wed Aug 19 2009 01:28 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

So the 1022 high pressure off the coast of NC will not effect it's movement?
http://www.ssd.noaa.gov/goes/east/nwatl/loop-wv.html


gatorman
(Verified CFHC User)
Wed Aug 19 2009 02:06 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

in almost every statement issued, in the past couple of days, the NHC has predicted a more northward turn. are they just that confused about the path, or have conditions changed?

sailor
(Verified CFHC User)
Wed Aug 19 2009 02:33 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

I think Beach is right on . That system may be just enough to delay Bill's turn and as a result Cape Cod may be in Bill's path.

MikeCAdministrator
(Admin)
Wed Aug 19 2009 02:38 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Actually Bill is a little more east than the NHC's forecast track from yesterday morning. But all in all it's been following the NHC's track fairly well. If you use the actual degree motion it also matches up well.


LoisCane
(Veteran Storm Chaser)
Wed Aug 19 2009 02:47 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

A lot of interesting data being gone over from the planes...

Storm has dry air even though he handles it well..

The front is still a question mark as to how strong..

And we have moved from a hurricane cruising by Cape Cod to being just barely in the cone...

Nova Scotia is in Bill's path...

We are far from watching a hurricane curve out to sea peacefully...

http://flhurricane.com/sbanimator.php?year=2009&storm=3


Thunderbird12
(Meteorologist)
Wed Aug 19 2009 03:01 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

While it is still very likely to miss the U.S. directly, nobody in New England should be turning their back on Bill right now. The developing upper-level trough will act like a brick wall that will keep Bill from making it very far west, but the exact evolution of the trough is yet to be determined. The extent to which the trough deepens and the timing of shortwave troughs ejecting from the main trough will determine whether Bill gets tugged on more of a northerly path, making a closer approach to the U.S., or gets shoved off more to the northeast away from the coast. The recent tendency of the models to nudge the track further west is a little worrisome, though the reliable models still send Bill somewhere into the Canadian maritimes.

Cape Cod, Nantucket, and parts of the Maine coast are all in the 5-day NHC forecast cone, so people in those areas should have a plan and be ready to put it into effect on short notice. Bill has a large circulation, so even without a direct hit, a more westerly approach could cause tropical storm force winds to affect the New England coast. Keep in mind, though, that by the time Bill gets caught up in the trough and begins to accelerate, the west side of the system will be much weaker than the east side, which could spare New England some problems. A more westerly approach would also likely cause more of a significant direct hit somewhere in the Canadian maritimes, rather than a glancing blow in those areas.


Ed in Va
(Weather Master)
Wed Aug 19 2009 03:08 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Agree with you about not letting guard down...NOGAPS shows a very close call.
http://moe.met.fsu.edu/cgi-bin/ngptc2.cg...;hour=Animation

I know the western side is always weaker, but but wonder why that it gets even weaker when caught up in a trough??


Fairhopian
(Weather Watcher)
Wed Aug 19 2009 03:15 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

I know this question gets posed fairly regularly, but I would appreciate it if someone would remind me of those attributes or conditions which might enable a hurricane to more or less "control its own destiny." Thanks!

MichaelA
(Weather Analyst)
Wed Aug 19 2009 03:47 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Quote:

I know the western side is always weaker, but but wonder why that it gets even weaker when caught up in a trough??


In a word? Shear. The upper level wind flow ahead of an advancing trough is from SW to NE. As a storm moves into and in response to that, it gets tilted out of the vertical.

MichaelA
(Weather Analyst)
Wed Aug 19 2009 03:56 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

The ngp seems to be the most westward leaning model at the moment, but not by very far. The rest are really pretty tight and in agreement a little more to the East. Cape Cod and the New England coastal areas need to keep a very wary eye on Bill. Any wobble to the West could be devastating. The WV sat loops, show a very complex pattern over the NW Atlantic right now. I'm assuming that the large trough over the mid-US is what will be the predicted steering mechanism as it moves eastward over the next couple of days. All in all, Bil is a very impressive system to watch.

Here is an animated gif from OSEI: Bill


doug
(Weather Analyst)
Wed Aug 19 2009 04:01 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

When I said Bill was out to sea a bit ago, I did not mean everybody should take the rest of the week off and forget about it. Not at all. But the overall evolving picture suggests that solution. This is playing out ,as Mike pointed out, in the fact that Bill is further east than the forecast points, and the fact that the trough off the east coast is digging south and that has not abated.
I think it is a very good chance that the east coast of the U.S. will be spared from this monster. thanks.


LoisCane
(Veteran Storm Chaser)
Wed Aug 19 2009 04:41 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

re: control its own destiny

imagine would be the high aloft above such a powerful storm gives it more powers than a regular storm to control its own destiny .... we often like to think of hurricanes poetically more than scientifically

not sure if that is what you meant

regarding TRCbill.gif... can anyone remember a storm that looked as much like this over this area..

tail touches landmass of south america...
amazing


doug
(Weather Analyst)
Wed Aug 19 2009 05:01 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Hello Lois:
I think you were responding to Fairhopian and yes that is the idea. These large powerful storms do generate their own area of higher pressure aloft as the clockwise outflow diffuses the air away from the system and often they can literally shove smaller features aside or absorb them. They dominate thousands of square miles of space. But they still respond to the genearal laws of physics. What can change sometimes unseen is the atmosphere being in gaseous form can suddenly change hundreds of miles from where the storm actually is and alter the whole dynamic. That is why nothing is etched in stone, ever, with these systems.


LoisCane
(Veteran Storm Chaser)
Wed Aug 19 2009 05:10 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Well said Doug. Often though people use that to believe it will do whatever it wants... giving it a sort of soul, in truth its dynamics and often the high just reinforces the current pattern but sometimes...over time... have seen some crazy things happen that were later attributed to it "making its own weather" and yet...all part of the overall stream of atmospheric conditions.

amazing, truly... to watch it all unfold.

and a slight variation in path over a part of a day can extrapolate into big distances over the longer term of the forecast


craigm
(Storm Tracker)
Wed Aug 19 2009 05:34 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Quote:

I know this question gets posed fairly regularly, but I would appreciate it if someone would remind me of those attributes or conditions which might enable a hurricane to more or less "control its own destiny." Thanks!



I would like to chime in on this one. I have asked myself the same question and my very unscientific conclusion is that as impressive as Bill is his energy pales in comparison to a polar trough, which is what is eroding the ridge. Strong Hurricanes can affect their immediate surroundings but as far as affecting fluid dynamics in an entire Hemisphere, which is what the models work with, I don't think that is possible. In the past decade I have only seen the NHC get more accurate especially with the 3 day cone. Trust the cone young skywalker.

BTW next piece of energy is emerging off of Africa
http://www.ssd.noaa.gov/eumet/eatl/rb-l.jpg


WeatherNut
(Weather Master)
Wed Aug 19 2009 05:43 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Just read the 5p discussion and it seems some models are now forecasting a stronger ridge and a slower trough on the east coast. Also the ensemble models have moved west which was also mentioned...this aint over till its over.

ftlaudbob
(Storm Chaser)
Wed Aug 19 2009 07:03 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

If I lived in New England I would be watching Bill VERY closely.It is still a long way off but the models have moved a little west.

Fairhopian
(Weather Watcher)
Wed Aug 19 2009 07:20 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Quote:

In the past decade I have only seen the NHC get more accurate especially with the 3 day cone. Trust the cone young skywalker.




Thank you, Lois, Doug, and Craig, for your rich responses to my question about when hurricanes might control their own destiny. You were all very much on point with what I was trying to ask.

I am afraid I will forever remain a tropical prediction "padwan", will always fall prey to personifying hurricanes, and will always hold the cone suspect. I blame these developmental defects on all of the grown-ups who warped me during my formidable years as they fought over such things as whether Frederic was a man or a woman, or as they did such things as assure me Elena had passed us by and headed off to Florida, etc..

Which is why it is great to be able to be able to request from y'all a little mental recalibration every now and then!

I have been "relying" on this site for hard-to-get preliminary info on storms for at least 7 years now, and really appreciate how much it has evolved.


JoshuaK
(Weather Guru)
Wed Aug 19 2009 08:00 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Latest model runs has Hurricane Bill over Halifax by Sunday afternoon, still at Category 2 strength. Could be a repeat of Hurricane Juan for the Canadians.

Random Chaos
(Weather Analyst)
Wed Aug 19 2009 09:50 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Today's spectacular photo of Bill:

http://rapidfire.sci.gsfc.nasa.gov/gallery/?2009231-0819/Bill.A2009231.1415.1km.jpg

Enjoy!


Beach
(Weather Guru)
Wed Aug 19 2009 09:55 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

It wouldn't surprise me if Bill is moving at 300 deg at 11pm:

http://www.ssd.noaa.gov/goes/flt/t2/loop-wv.html


LoisCane
(Veteran Storm Chaser)
Thu Aug 20 2009 09:00 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

some real time changes in the models .. especially with regard to gfs and bill gets a lot closer to new england and will be very interesting to see how much the track from nhc changes...

was hinted at in the 5am discussion

guess there aren't a lot of new england posters here.. east coast is going to see some great waves if nothing else

and a breeze maybe


Ed in Va
(Weather Master)
Thu Aug 20 2009 09:17 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

You're right on the 5:00 discussion...sort of wierd...why not change the track if you think it's not right??
IT SHOULD BE NOTED THAT BILL WILL
PROBABLY NOT TURN AS SHARPLY BETWEEN 72-96 HR AS IMPLIED BY THE
TRACK GRAPHIC...AND THUS IS LIKELY TO PASS CLOSER TO NEW ENGLAND
THAN THE GRAPHIC WOULD SUGGEST.

Also, what are the implications with the slight weakening...will this make the recurvature less pronounced?


blizzardnut
(Verified CFHC User)
Thu Aug 20 2009 09:41 AM
Re: Bill weakens Some, New England/Canada Needs to Watch

Well, one frequent lurker/rare poster from New England here. The early summer pattern seemed to pull EVERYTHING back off the ocean, and if Bill were in June, I'd be very interested - not that I'm not now, just pretty skeptical that it will do much other than create interesting seas off Cape Cod. The more recent pattern, since about August 1st, seems a lot more typical. Still, the trough approaching may be a lot deeper than many, reminiscent of those that generated the unending train of closed lows that made the first half of the summer completely miserable here. If forecasts started to predict it going negative tilt, THAT would be interesting.

We had 13.8 inches of rain here in July, second most in my lifetime!


Fairhopian
(Weather Watcher)
Thu Aug 20 2009 09:43 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

How do you explain that Bill as a Cat 4 had baro pressure of 950mb, but now as a Cat 3, Bill's baro pressure is 949mb (lower)? Why aren't the sustained winds correlating with the pressure?

doug
(Weather Analyst)
Thu Aug 20 2009 10:00 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Not always. Wind speed is relative and determined by pressure differentials in large part to be sure. But there are other factors, such as size of the system; whether the system is in a replacement cycle and many others. In this instance the 5 a.m. discussion suggests shear is affecting the eyewall thunderstorm heights and that strenghtening will recur after the shear lessens.

Hugh
(Senior Storm Chaser)
Thu Aug 20 2009 10:37 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Quote:

You're right on the 5:00 discussion...sort of wierd...why not change the track if you think it's not right??
IT SHOULD BE NOTED THAT BILL WILL
PROBABLY NOT TURN AS SHARPLY BETWEEN 72-96 HR AS IMPLIED BY THE
TRACK GRAPHIC...AND THUS IS LIKELY TO PASS CLOSER TO NEW ENGLAND
THAN THE GRAPHIC WOULD SUGGEST.
Also, what are the implications with the slight weakening...will this make the recurvature less pronounced?




They did not say they did not think the forecast was right.
They said Bill will probably not turn as sharply as IMPLIED by the track graphic.
The track grahic marks the specific predicted location at 72 hours, and again at 96 hours,
and a straight line is drawn between the two points. What the discussion is noting is that
the movement between 72 and 96 hours is not likely to be a straight line between those two points,
but rather a gradual curve, which could put the circulation closer to the coast between 72 hours and 96 hours.


hogrunr
(Weather Guru)
Thu Aug 20 2009 10:46 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Quote:

Quote:

I know this question gets posed fairly regularly, but I would appreciate it if someone would remind me of those attributes or conditions which might enable a hurricane to more or less "control its own destiny." Thanks!



I would like to chime in on this one. I have asked myself the same question and my very unscientific conclusion is that as impressive as Bill is his energy pales in comparison to a polar trough, which is what is eroding the ridge. Strong Hurricanes can affect their immediate surroundings but as far as affecting fluid dynamics in an entire Hemisphere, which is what the models work with, I don't think that is possible. In the past decade I have only seen the NHC get more accurate especially with the 3 day cone. Trust the cone young skywalker.

BTW next piece of energy is emerging off of Africa
http://www.ssd.noaa.gov/eumet/eatl/rb-l.jpg





Just noticed on the CMC model, both sea-level pressure and 850mb vorticity model, has this next wave off of Africa developing and coming close to mimicking the path of Ana. Not disregarding Bill at all, but we will have to keep an eye on the back door as well now.


MichaelA
(Weather Analyst)
Thu Aug 20 2009 10:58 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

The CMC is the only model doing that, so I'll take that output with a grain of salt. Of more interest to me is the trough just off the East coast appears to be cutting off East of the Carolinas and moving SW which seems to indicate that its influence on Bill will be decreased significantly.

Northwest Atlantic WV loop


danielwAdministrator
(Moderator)
Thu Aug 20 2009 11:36 AM
Bill at Cat 4

Bill is one tattered and torn up looking Cat 4 storm right now. The arc moving away from the storm that was mentioned in the latest Discussion is clearly seen below in the RBG enhancement.
IN FACT...SOME ARC
CLOUDS ARE MOVING AWAY FROM THE HURRICANE SUGGESTING THAT BILL IS
NOT STRENGTHENING AT THIS TIME.


Bill is still below 25.0N which is the latitude for the Southern Tip of Florida. I would at least keep a 12 hour watch on him right now. That's a glance every 12 hours... or or 6 hours. Just don't stay glued to Bill he won't seem to move if you do that. Ha!

Something going on with that storm and I'm not sure if it's the dry air or the shear or both. Not a healthy looking Cat 4.

Looking at the RGB above. It would seem to appear that the lower storm is outrunning the mid and upper storm. An eastward tilt.


WeatherNut
(Weather Master)
Thu Aug 20 2009 11:45 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

I also noticed the tilt as well. Looking at WVI it seems that it might give Bill a slight western nudge. Also, the eye looks to be in much better shape in the last couple of frames and is more symmetric.

OrlandoDan
(Weather Master)
Thu Aug 20 2009 12:24 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

We have got some decent size wave heights coming this weekend. See the attached link, click on your sector, select the time period on the resultant screen, and then mouse over the "wave height" text in the table.

http://www.weather.gov/forecasts/graphical/sectors/


MichaelA
(Weather Analyst)
Thu Aug 20 2009 12:55 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

The last few vis frames indicate that the core may have strengthened somewhat with the eye closing off again with a good looking central core. That outflow to the West appears to be a gust front from the collapsed convection in that quadrant earlier - dry air intrusion?

hogrunr
(Weather Guru)
Thu Aug 20 2009 03:00 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Quote:

The CMC is the only model doing that, so I'll take that output with a grain of salt. Of more interest to me is the trough just off the East coast appears to be cutting off East of the Carolinas and moving SW which seems to indicate that its influence on Bill will be decreased significantly.

Northwest Atlantic WV loop




A TROPICAL WAVE IS ALONG 23W S OF 18N MOVING W AROUND 10 KT. THE
WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYERED MOISTURE MAXIMUM
OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY. AN INVERTED-V
LOW LEVEL SIGNATURE IS NOTED ON VIS SATELLITE PICTURES WITH SOME
CYCLONIC TURNING NEAR THE INTERSECTION OF THE WAVE WITH THE
ITCZ. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 160-200 NM
EITHER SIDE OF THE WAVE AXIS. THE WAVE WILL CONTINUE TO MOVE
ACROSS THE CAPE VERDE ISLANDS THIS AFTERNOON.


Above from the 2pm NHC discussion. Agreed that it's not top priority right now. However, the 12z run of the GFS, CMC, and the UKMET models are all picking up this feature now. Still waiting on the rest of the 12z models to become available. Of course this is very very early since the wave is really just now fully over water, so the direction and strength, if this does develop, is still highly up for debate and probably won't be well known until Bill is clearly out of the region.

Interesting picture, you can see the drier air that Bill is starting to suck in as well as the increase in precipitable water off the African coast with the new wave that is now present.

MIMIC-TPW


Random Chaos
(Weather Analyst)
Thu Aug 20 2009 09:32 PM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Recon is in the storm.

Satellite presentation shows convection real weak on the WNW side. Dropsonde found only 67kt winds in the eyewall over there.

However, the other side (east side) HDOB data is big. Flight level winds at 159kts with an SFMR surface estimate of 121kts. Dropsonde that landed a good bit north of the plane track recorded only 105-110kt surface winds in that same region, but could have easily missed the max.

Central pressure from HDOB indicates an estimate of 942mb. Last pass recon vortex came in at 946mb with an HDOB estimate of 940mb, so I doubt there is much change vs the last pass in that area, but it appears this time they found the wind.

--

Edit: NHC chimed in at 11pm saying the flight crew didn't think the 159kt flight level wind and corresponding SFMR were valid.

Still Cat 3.


M.A.
(Weather Guru)
Fri Aug 21 2009 07:00 AM
Re: Bill a Category Four Hurricane, Likely No Threat to US

Bill is looking quite ragged this morning. Either an ERC or drawing in some dry air. Either way he does not look like a Cat3 this morning. It almost looks as though the western portion of the circulation convection has collapsed. Could the shear be a little stronger than forecasted?

danielwAdministrator
(Moderator)
Fri Aug 21 2009 07:28 AM
MJO Forecast

THE MJO FORECAST REMAINS THE SAME AS PREVIOUSLY
INDICATED/DISCUSSED...WITH BOTH CFS AND EWP MODELS SHOWING
FAVORABLE CONDITIONS (NEGATIVE ANOMALIES) PERSISTING THROUGH THE
END OF AUGUST. THEY...HOWEVER...CONTINUE TO DIVERGE ON BEST
LOCATION...WITH THE CFS FAVORING THE CARIBBEAN/NORTHERN SOUTH
AMERICA AND THE EWP THE ATLANTIC BASIN. THE MEDIUM RANGE MODELS
HAVE SETTLED ON A LULL IN ACTIVITY...AS THEY NO LONGER SHOW
TROPICAL SYSTEMS DEVELOPING ACROSS THE DOMAIN. THEY TRY TO RELEASE
AVAILABLE ENERGY IN THE FORM OF HEAVY RAINFALL EVENTS IN
ASSOCIATION WITH THE MANY TUTTS AND ALONG THE NEAR EQUATORIAL
TROUGH/ ITCZ...WITH MOST ACTIVE CONVECTION OVER CENTRAL/WESTERN
VENEZUELA-NORTHERN HALF OF COLOMBIA AND SOUTHERN PORTIONS OF
CENTRAL AMERICA.
http://www.srh.noaa.gov/data/WBC/PMDCA

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
201 PM EDT THU AUG 20 2009

VALID 12Z SUN AUG 23 2009 - 12Z THU AUG 27 2009
edited
TROPICS..HURCN BILL MOVES NWD GETTING AS FAR WEST 68W-69W WITH
VERY HEAVY SWELL AND SURF IMPACTING THE EAST COAST WITH HIGHER
WINDS AND SEAS AFFECTING NEW ENGLAND AND INTO MARITIME CANADA DAYS
3 AND 4. CHI VELOCITY ANOMALY INDICATES THAT THE ATLANTIC BECOME
RELATIVELY UNFAVORABLE FOR ADDITIONAL DEVELOPMENT WITH SOME
CONSENSUS OF A WAVE MOVING THE BAHAMAS REGION LATE PERIOD BUT THE
EPAC WILL BE UNDER HIGHLY FAVORABLE CONDITIONS AND MODELS GENERATE
AT LEAST 3 SYSTEMS IN THE MEDIUM RANGE TIME FRAME.
http://www.srh.noaa.gov/data/WBC/PMDEPD


LoisCane
(Veteran Storm Chaser)
Fri Aug 21 2009 08:44 AM
Re: MJO Forecast

Thank you Daniel, appreciate you posting that. Lost in thinking on Bill and not beyond Bill.

Think the present presentation of Bill is just a reality of what has been for most the time. We are compelled and drawn in by his immense size but internally something always seemed not quite right with him and I always found it hard to accept he was a 4. Mentally I accept the data analytically but he was never quite perfectly formed, tilted or had dry air in him often and suddenly the illusion is pulled away (saying this poetically vs scientifically because others here are better at the scientific terms) and he is what he is... and no matter what someone will have to deal with him. Been watching the reports from the Canadian Hurricane Centre to keep things in perspective.


doug
(Weather Analyst)
Fri Aug 21 2009 09:36 AM
Re: Bill presentation

What I see this a.m. is that Bill is behaving according to plan. Movement now NNW and the eye is becoming better structured and well positioned. That may be consistent with decreasing Sw'ly shear. I think some strenghtening will occur due to SST's. It looks as if 69W or so is as close as the system will traverse westward.

Ed in Va
(Weather Master)
Fri Aug 21 2009 09:36 AM
Re: MJO Forecast

It's may just be a wobble and it's harder now to see the COC, but if you click on forecast points with this, it looks like he's east of the projected track...which would be more of an issue for Bermuda.
http://www.ssd.noaa.gov/goes/flt/t2/flash-vis.html


scottsvb
(Weather Master)
Fri Aug 21 2009 11:44 AM
Re: MJO Forecast

No Hurricane conditions will affect Bermuda..but they will get 35-50mph winds and a couple tornados in squalls. Bill has already bypassed Bermuda in longitude..and wont make more of a NNE turn until it passes the latitude.

Kent
(Weather Guru)
Fri Aug 21 2009 11:52 PM
Re: Bill weakens some more, No Direct Impact to New England

Just wanted to share my favorite link for watching these storms. Its easy for a novice like me to see the front thats blocking Bill from hitting the east coast. I find it mesmerizing to watch.

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12


blizzardnut
(Verified CFHC User)
Sat Aug 22 2009 12:31 PM
Re: Bill Could Brush Nova Scotia as a Cat I on Sunday

We enjoyed a beautiful morning here in Central MA, courtesy of Bill's subsidence keeping clouds/showers from an approaching front down. Unusual to see bright blue tropical skies with high humidity around here. 85/73 at noon here. Wind just shifted from SW to light easterly the past hour or so. Buoy 44008 south of Nantucket has long-period swells up to about 10 feet... cool.

Looks like Bill may finally be getting his act back together just a bit, with more hints of a better eye the last few satellite frames. Not much more time over the Gulf Stream though. It'd be fun to be up on Cape Breton Island tomorrow.


danielwAdministrator
(Moderator)
Sat Aug 22 2009 02:25 PM
Week Ahead

Excerpt from the morning Extended Forecast Discussion.

EWD A TROPICAL WAVE CURRENTLY SW OF THE CAPE VERDE ISLANDS MAY APPROACH THE BAHAMAS THURSDAY WITH SHOWERS POSSIBLY REACHING FL BY FRIDAY. CMC CONTS TO BE VERY AGGRESSIVE WITH THIS WAVE WHILE 00Z ECMWF ENSEMBLES SHOW A STRONG CLUSTERING OF LOWS IN THIS REGION LATE WEEK. CHI VERTICAL VELOCITY POTENTIAL ANOMALY CHARTS STRONGLY FAVOR THE TROPICAL EPAC FOR DEVELOPMENT THIS PERIOD WITH SOME LESSER BUT STILL FAVORABLE CONDITIONS OVER THE CARRIBEAN/GLFMEX AND BAHAMAS REGION. LATEST 12Z UKMET/CMC MAINTAIN CONTINUITY INDICATING A TROPICAL WAVE OR GREATER WILL BE IN THIS REGION LATE NEXT WEEK. SFC POSITIONS DEPICTED BY DAILY HPC/TPC COORDINATION.

And from the
Preliminary Extended Forecast Discussion
UPDATED MORNING PROGS INCORPORATE THE 00Z ECMWF ENS MEAN TO A CONSIDERABLE DEGREE INCREASING IN TIME ALONG WITH THE OP ECMWF. SFC FRONTAL POSITIONS ARE LITTLE DIFFERENT FROM EARLIER PRELIMS. BY DAYS 6 AND 7 HAVE ENHANCED THE DEPICTION OF THE TROPICAL WAVE IN THE BAHAMAS AND OFF THE FL EAST COAST AS PER OP MODEL SOLUTIONS AND IMPROVING VELOCITY POTENTIAL ANOMALY CHARTS OF EMWF/GFS AND ECMWF INDICATING BETTER CONDITIONS FOR TROPICAL DEVELOPMENT ONCE THE WAVE ENTERS THE BAHAMAS REGION. GOOD ENSEMBLE SFC LOW CLUSTERING NORTH OF THE BAHAMAS DAYS 5-7 THU-SAT.

note:NWS Florida Peninsula Offices are not giving this much more than a mention at this time.~danielw


MichaelA
(Weather Analyst)
Sat Aug 22 2009 05:24 PM
Re: Bill Could Brush Nova Scotia as a Cat I on Sunday

It looks like Bill has begun the turn toward the NE in the last couple of frames of the floater vis loop. A stormy night is in store for Cape Cod and Nantucket Sound, however. Nova Scotia and Newfoundland won't be quite so fortunate.

JoshuaK
(Weather Guru)
Sun Aug 23 2009 06:56 AM
Re: Bill Could Brush Nova Scotia as a Cat I on Sunday

I stayed up most of last night, check on sat and radar images every so often. Looks like Natucket got a good amount of rainfall and some wind. According to the wind history, looks like Tropical storm force winds are already affecting Nova Scotia and Halifax. It's going to be a long day today in that harbor town.

scottsvb
(Weather Master)
Sun Aug 23 2009 10:59 AM
Re: Bill Could Brush Nova Scotia as a Cat I on Sunday

Reports from there say that they recieved minor affects...some decents rains..winds gusting 30-50mph...but nothing what could of been. Bill was the typical easy forecasted (straight forecast) for days of making only a glancing touch if any to the U.S.

blizzardnut
(Verified CFHC User)
Sun Aug 23 2009 01:58 PM
Re: Bill Could Brush Nova Scotia as a Cat I on Sunday

Winds and rain are not a tremendous issue according to the latest Environment Canada statement, but seas/surf are. There will likely be quite a few wrecked docks, etc on the south coast of Nova Scotia and Cape Breton. Astronomical tides are high in this area this weekend, making the coast more vulnerable than usual. And look at these seas... over 40 feet! Glad I'm not on a boat offshore!

http://www.ndbc.noaa.gov/station_page.php?station=44137


OrlandoDan
(Weather Master)
Sun Aug 23 2009 07:42 PM
Re: Bill Could Brush Nova Scotia as a Cat I on Sunday

The NHC just put up the following for the wave at 17N, 51W:

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN AUG 23 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
BILL...LOCATED ABOUT 230 MILES WEST OF CAPE RACE NEWFOUNDLAND.

1. SHOWERS AND THUNDERSTORMS HAVE INCREASED OVER THE PAST SEVERAL HOURS
IN ASSOCIATION WITH A TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL
LOW ABOUT 600 MILES EAST OF THE LEEWARD ISLANDS. ANY DEVELOPMENT OF
THIS SYSTEM WILL BE SLOW TO OCCUR OVER THE NEXT COUPLE OF DAYS AS
IT MOVES TOWARD THE WEST-NORTHWEST AT 20 TO 25 MPH. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BRENNAN
NNNN



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