Claudette hits Florida; Ana approaches Puerto RIco; Bill becomes our first hurricane

By: Dr. Jeff Masters , 2:10 PM GMT on August 17, 2009

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Tropical Storm Claudette made landfall at about 1:15 am EDT near the eastern end of Santa Rosa Island, just southeast of Fort Walton Beach in Florida. Claudette's top winds were around 50 mph. A Personal Weather Station in Eastpoint, FL recorded sustained winds of 49 mph, gusting to 66 mph last night. So far, the rain from Claudette has had a tough time penetrating inland (Figure 2). Heavy rains of 3 - 4 inches have been confined to a narrow strip of coast, and Claudette is unlikely to cause any major flooding. Apalachicola received just over 4 inches of rain so far from Claudette. Radar animations out of the Florida Panhandle show that heavy rains continue along the coast in association with a main spiral band of Claudette, and these rains will gradually subside today.


Figure 1. Radar reflectivity image of Tropical Storm Claudette as it approached landfall just southeast of Fort Walton Beach shortly after midnight on 8/17/09.

The tropics featured a rare triple threat the past two days--simultaneous named storms beginning with the letters A, B, and C. The last time this occurred was in the slow-starting 1984 hurricane season, when Tropical Storms Arthur, Bertha, and Cesar were all active on September 1. This year's A, B, and C storms all got their names in just a 33 hour span. This is not a record, since in 1995, three tropical storms--Humberto, Iris, and Jerry--got their names in a 27-hour span (thanks to NOAA's Ryan Sharp for looking up this stat).


Figure 2. Total precipitation estimated by radar for Claudette, as of 3:28pm EDT 8/17/09.

Ana not dead yet
Tropical Depression Ana continues to cling to life, and is now approaching landfall in Puerto Rico. Radar animations from the San Juan, Puerto Rico radar show a surface circulation just southeast of the island, with some low-level spiral banding trying to develop to the south. Recent satellite images also show a rejuvenation of the heavy thunderstorm activity near Ana's center, as the storm regroups from being nearly torn apart yesterday. Ana has already dumped up to 4 inches of rain along the north coast of Puerto Rico, according to radar-estimates.

It is unlikely that Ana will survive past today, however, since the storm will move over both Puerto Rico and the rugged terrain of Hispaniola. The high mountains of these islands should act to disrupt the relatively small and fragile circulation of Ana. None of the computer models foresee that Ana will survive passage over Hispaniola. The Dominican Republic can expect 3 - 6 inches of rain from Ana, and Haiti can expect 1 - 3 inches.


Figure 3. Total precipitation estimated by radar from Ana for Puerto Rico.

Bill becomes the first Atlantic hurricane of 2009
Hurricane Bill continues to gather strength, and is now the first hurricane of the 2009 Atlantic hurricane season. An eye has appeared on visible and infrared satellite imagery, and Bill is displaying an impressive symmetry, with plenty of low-level spiral banding.

Wind shear is low, 5 - 10 knots, and is forecast to be in the low range through Wednesday. With Sea Surface Temperatures only 27°C today, substantial intensification may not occur until Tuesday and Wednesday, when SSTs warm to 28 - 29°C and ocean heat content sharply increases. By Thursday, Bill is expected to leave the favorable upper-level wind environment it currently finds itself in, and moderate shear of 15 - 20 knots may limit further intensification.

Water vapor satellite imagery shows that there is a modest trough of low pressure in the upper atmosphere near 50°W longitude, that Bill is currently approaching. All of the computer models except the UKMET predict that this trough will be strong enough to turn Bill more to the northwest so that the hurricane misses the Lesser Antilles Islands. The UKMET predicts the trough will not affect Bill much, and that the hurricane will pass through or just north of the islands on Thursday. For now, the UKMET solution is being discounted, since the trough at 50W appears substantial enough on satellite imagery to be able to turn Bill more to the northwest.

A much larger trough of low pressure is expected to develop along the U.S. East Coast late this week, turning Bill even more to the northwest. Most of the models predict Bill will pass very close to Bermuda on Saturday as a result. The HWRF model predicts Bermuda will receive a direct hit at Category 4 strength. Until Bill interacts with the small trough at 50°W, it is too early to be confident of the potential threat to Bermuda. By Tuesday, we should have a much better idea of the threat. Likewise, I would like to see the UKMET model come around in line with the other models before dismissing the possible threat to the U.S. East Coast. It currently appears that Bill will miss the U.S. East Coast, but that a strike on the Canadian provinces of Newfoundland or Nova Scotia is possible.

I'll have an update Tuesday morning, or possibly this afternoon.

Jeff Masters

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I see on the latest advisory that Anna is now forecast to stay a depression when/if it passes over South FL instead of a remnant low. Interesting...we could definitely use the rain!
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Quoting canesrule1:
Bill currently located 45.4N 14.9W


erm, that would be somewhere in the East Atlantic north-west of Spain and west of France, if I'm not totally mistaken.

Did you mean 14.9 N 45.4 W?
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Quoting Patrap:
On a sidenote,DrakoenG/WS has been permanently IP banned.

Monomania,and circumventing a BAN will get that every time as we are in a active Period.

Do not quote Trolls,or any obvious troll mannerisms
they have been replaced with empty space just like whats in there head

good about time
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271. jipmg
The hurricane hunters should be in "ANA" in about 3-4 hours
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Quoting Drakoen:
Apparently the circulation near the SE coast is mid level. The HH will be able to confirm whether or not it is going down to the surface.


If it does, and it becomes the dominant circulation center then that will change things. One too many variables to play around with right now....until it establishes a proper center. I think if the mid-level circulation takes over, land interaction may well decrease and allow the system to organize properly.
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Quoting IKE:
It currently appears that Bill will miss the U.S. East Coast, but that a strike on the Canadian provinces of Newfoundland or Nova Scotia is possible.
......

Maybe what Dr. Masters said will put some sanity back in this blog....


I doubt it. Some people still want to cling to the possibility that it will slam into the east coast.
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Quoting Drakoen:



Thank God!!! The day has finally come


Well, that ought to put to rest that you and he were one and the same! :)
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Quoting IKE:


I was thinking about him the other day. He hasn't been around at all. Somethings up.


He is still there.

The other trolls are still there too
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Quoting Drakoen:
I wonder if BurnedAfterPosting/Jphurricane was permanently banned as well.


Just go to the directory,scroll down to a given name,and click on the entry,..if you get the message,you'll know.
Member Since: July 3, 2005 Posts: 423 Comments: 127902
Quoting Drakoen:
Hurricane Hunters will be leaving at 16z to go into Ana and arrive there at 18z
they will be leaving in about 45 minutes, and i will keep all u posted.
I don't know about this, but I think Ana might make it through the Dominican Republican.
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262. IKE
Quoting Drakoen:
I wonder if BurnedAfterPosting/Jphurricane was permanently banned as well.


I was thinking about him the other day. He hasn't been around at all. Somethings up.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting AllStar17:


Maintained as a depression throughout the forecast period. If a new center does indeed form SE of PR, and moves over PR, it would currently appear it would track just to the north of Hispaniola, or graze Hispaniola. If it stays north of Hispaniola it is likely to regain Tropical Storm strength. NHC even says it:
" THIS IS...ADMITTEDLY...
SOMETHING OF A HEDGE BETWEEN TWO MORE LIKELY ALTERNATIVES...THAT OF
A TROPICAL STORM NORTH OF THE ISLANDS OR IMMINENT DISSIPATION."

Models at this point may not have been initialized correctly.....Hurricane Hunters will REALLY help determine what is going on with the so-called "circulation" SE of Puerto Rico. If they do indeed find a circulation there, NHC will probably need to make large changes in intensity and track forecast of Ana if that does indeed become true. JMO.


When will they fly in there?
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bouy is reading 998 and dropping fast.
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Quoting sullivanweather:
I'm sure there was some internal discussions to discontinue advisories but looking at their phrasing they're erring on the side of caution with this system being close to populated land and, of course, waiting for confirmation from reconnaissance.


When I woke up early this morning, I was wondering the same thing. I guess they took into account her previous reincarnations.
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I wonder if BurnedAfterPosting/Jphurricane was permanently banned as well.
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BILL IS MOVING TOWARD THE WEST-NORTHWEST NEAR 16 MPH...26 KM/HR...
AND THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF DAYS.


You see, Bill is slowing down, and it is going to the wnw these are signs that it is starting to turn. I doubt it will make landfall on the east coast or even effect it for that matter, but you can never be too careful, we just have to wait and see
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256. jipmg
Quoting canesrule1:
Bill currently located 45.1N 14.9W


can I have a link to the satellite ur using, seems to be updating quicker
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Hurricane Hunters will be leaving at 16z to go into Ana and arrive there at 18z
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Quoting canesrule1:


Maintained as a depression throughout the forecast period. If a new center does indeed form SE of PR, and moves over PR, it would currently appear it would track just to the north of Hispaniola, or graze Hispaniola. If it stays north of Hispaniola it is likely to regain Tropical Storm strength. NHC even says it:
" THIS IS...ADMITTEDLY...
SOMETHING OF A HEDGE BETWEEN TWO MORE LIKELY ALTERNATIVES...THAT OF
A TROPICAL STORM NORTH OF THE ISLANDS OR IMMINENT DISSIPATION."

Models at this point may not have been initialized correctly.....Hurricane Hunters will REALLY help determine what is going on with the so-called "circulation" SE of Puerto Rico. If they do indeed find a circulation there, NHC will probably need to make large changes in intensity and track forecast of Ana if that does indeed become true. JMO.
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Bill currently located 45.2W 14.9N
Quoting Patrap:
On a sidenote,DrakoenG/WS has been permanently IP banned.

Monomania,and circumventing a BAN will get that every time as we are in a active Period.

Do not quote Trolls,or any obvious troll mannerisms



Thank God!!! The day has finally come
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guys I think that ANA will be something like FAY and GUSTAV
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Ana's survival is dependent on how much she interacts with Hispaniola and Cuba. If she skirts the southern edge, she can survive and could regenerate in the warm waters of the Gulf. If she goes further north and spends any significant time over these bodies of land, then RIP Ana. Regardless she has been a very resilient storm.
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Bill currently moving NW.
Quoting sullivanweather:
I'm sure there was some internal discussions to discontinue advisories but looking at their phrasing they're erring on the side of caution with this system being close to populated land and, of course, waiting for confirmation from reconnaissance.


I agree.
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246. jipmg
Quoting weatherboykris:
If
Ana survives its path over the Greater Antilles and emerges to the
north of the Dominican Republic...the global models suggest that a
more favorable upper wind pattern will be present there.
Consequently...the official forecast maintains Ana as a tropical
cyclone through the forecast period. This is...admittedly...
something of a hedge between two more likely alternatives...that of
a tropical storm north of the islands or imminent dissipation.
Forecast positions and Max winds


Given the storm's persistence to this point...my money is on the first option.


We will have to keep an eye on the radar to see where the main circulation is
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Apparently the circulation near the SE coast is mid level. The HH will be able to confirm whether or not it is going down to the surface.
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Quoting Patrap:
On a sidenote,DrakoenG/WS has been permanently IP banned.

Monomania,and circumventing a BAN will get that every time as we are in a active Period.

Do not quote Trolls,or any obvious troll mannerisms


Member Since: Posts: Comments:
If
Ana survives its path over the Greater Antilles and emerges to the
north of the Dominican Republic...the global models suggest that a
more favorable upper wind pattern will be present there.
Consequently...the official forecast maintains Ana as a tropical
cyclone through the forecast period. This is...admittedly...
something of a hedge between two more likely alternatives...that of
a tropical storm north of the islands or imminent dissipation.
Forecast positions and Max winds


Given the storm's persistence to this point...my money is on the first option.
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I'm sure there was some internal discussions to discontinue advisories but looking at their phrasing they're erring on the side of caution with this system being close to populated land and, of course, waiting for confirmation from reconnaissance.
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Looks like Bill wont be any problem anymore for Florida? :)
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Quoting DestinJeff:
This should be of concern to mid-atlantic, north ... if you are a prudent resident



I was thinking the same thing. I'm up in DC and I've got my eye on this one.
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BILL DISCUSSION

000
WTNT43 KNHC 171435
TCDAT3
HURRICANE BILL DISCUSSION NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
1100 AM AST MON AUG 17 2009

SATELLITE IMAGERY INDICATES THAT BILL CONTINUES TO INTENSIFY THIS
MORNING...WITH A UNIFORM CENTRAL DENSE OVERCAST AROUND THE CENTER.
THE INTENSITY IS RAISED TO 80 KT BASED ON A DVORAK T-NUMBER OF 4.5
FROM TAFB AT 1200 UTC. MICROWAVE IMAGERY FROM A 1132 UTC TRMM PASS
SHOWS SEVERAL CONVECTIVE BANDS SPIRALING AROUND THE CENTER...BUT NO
EVIDENCE OF AN EYE. BILL SHOULD PASS VERY CLOSE TO NOAA BUOY 41041
IN THE NEXT FEW HOURS...WHICH SHOULD HELP PROVIDE INFORMATION ON
THE WINDS AND CENTRAL PRESSURE OF THE CYCLONE.

THE OCEANIC AND ATMOSPHERIC ENVIRONMENT CONTINUES TO BE FAVORABLE
FOR INTENSIFICATION. WHILE THE SHIPS RI INDEX SHOWS A 35 PERCENT
CHANCE OF AN INCREASE OF 30 KT OR MORE IN THE NEXT 24 HOURS...
MICROWAVE IMAGERY SUGGESTS THAT BILL DOES NOT YET HAVE A WELL
DEFINED INNER CORE STRUCTURE. THE OFFICIAL INTENSITY FORECAST
IS ABOVE THE PREVIOUS PACKAGE FOR THE FIRST 36 HOURS DUE TO THE
OBSERVED INTENSIFICATION AND IS IN BEST AGREEMENT WITH SHIPS AND
LGEM. BEYOND THAT TIME...THE STATISTICAL MODELS SHOW THE INTENSITY
LEVELING OFF...WHILE THE HWRF AND GFDL SHOW STRENGTHENING THROUGH
THE END OF THE PERIOD. GIVEN THIS UNCERTAINTY...THE OFFICIAL
FORECAST SHOWS A PEAK IN INTENSITY AT DAYS 3 AND 4...AND A SLIGHT
DECREASE AT DAY 5.

BILL CONTINUES ON A HEADING OF 285/14...WITHIN THE DEEP-LAYER FLOW
OF A RIDGE EXTENDING WESTWARD OVER THE CENTRAL ATLANTIC FROM
AFRICA. GLOBAL MODELS AND WATER VAPOR IMAGERY INDICATE A PERSISTENT
MID-ATLANTIC TROUGH SITUATED ALONG 53W WHICH SHOULD CAUSE THE
CYCLONE TO TURN MORE TOWARD THE NORTHWEST BY DAY 3. BEYOND THIS
TIME...THE FLOW AROUND A LARGE MID- TO UPPER-LEVEL LOW THAT
DEVELOPS OVER THE EASTERN UNITED STATES SHOULD INDUCE A MORE
NORTH-NORTHWESTWARD TURN. ALL OF THE TRACK MODEL GUIDANCE...WITH
THE EXCEPTION OF THE UKMET...IS IN GOOD AGREEMENT ON THIS SCENARIO.
THE UKMET HAS A MUCH STRONGER SUBTROPICAL RIDGE THAN THE REST OF
THE GLOBAL MODELS AND THE GFS AND ECMWF ENSEMBLE MEANS. AS A
RESULT...THIS MODEL KEEPS BILL TOO FAR SOUTH TO FEEL THE EFFECTS OF
THE CLOSED LOW LATE IN THE PERIOD. THE OFFICIAL FORECAST IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS PACKAGE THROUGH DAY 3...AND
IS SHIFTED SLIGHTLY TO THE RIGHT TOWARD THE MODEL CONSENSUS AT DAYS
4 AND 5.

THE INITIAL 34-KT WIND RADII WERE MODIFIED BASED ON A 0920 UTC
QUIKSCAT PASS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 17/1500Z 14.1N 45.2W 80 KT
12HR VT 18/0000Z 14.7N 47.5W 90 KT
24HR VT 18/1200Z 15.5N 50.1W 95 KT
36HR VT 19/0000Z 16.6N 52.6W 100 KT
48HR VT 19/1200Z 18.0N 55.1W 105 KT
72HR VT 20/1200Z 21.5N 60.0W 110 KT
96HR VT 21/1200Z 26.0N 64.0W 110 KT
120HR VT 22/1200Z 31.5N 66.5W 105 KT

$$
FORECASTER BRENNAN/ROBERTS

The hurricane hunters will really give us an idea of what this system is and where it is going.
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Good Morning All. Nice to see the blog more subdued this morning.
Member Since: May 13, 2008 Posts: 0 Comments: 1412
Have all the models fallen into agreement about the forecasted track for Bill? If not, what are the outliers?
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Remember the golden rule of ANA.



It is a meteorlogical factoid that she can't possibly re-strengthen untill the NHC and everyone on this board writes her off.

This one is engraved in stone!


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Quoting Patrap:
On a sidenote,DrakoenG/WS has been permanently IP banned.

Monomania,and circumventing a BAN will get that every time as we are in a active Period.

Do not quote Trolls,or any obvious troll mannerisms


Pat, How can someone tell if a blogger has been banned?
TIA
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Quoting Drakoen:
The NHC is tracking the southern circulation for now...


It will be very interesting to see if the HH find sfc. circulation SE of PR (northern one)

Also, NHC discussion sounds like they are very uncertain about this storm:
000
WTNT42 KNHC 171500
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER 22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
1100 AM AST MON AUG 17 2009

THE CENTER OR WAVE AXIS OF ANA PASSED OVER BUOY 42060 AROUND
0830Z...AND IF A CENTER EXISTED AT THAT TIME IT WAS SOUTH OF THE
BUOY. THERE WAS ONE SHIP REPORT WITH A LIGHT WEST WIND AT 12Z.
SINCE THAT TIME...NEW CONVECTION WITH A MID-LEVEL SPIN HAS
DEVELOPED NEAR THE SOUTHEAST COAST OF PUERTO RICO. GIVEN THESE
HINTS...WE WILL CONTINUE ADVISORIES AT LEAST UNTIL A RECONNAISSANCE
AIRCRAFT INVESTIGATES ANA THIS AFTERNOON.

WITH A CENTER POSITION ESTIMATE BASED ON A BLEND OF CONTINUITY AND
THE MID-LEVEL ROTATION SEEN IN THE RADAR DATA...THE INITIAL MOTION
IS 285/24. ANA IS EXPECTED TO CONTINUE ON A GENERAL WEST-
NORTHWESTWARD TRACK TO THE SOUTH OF THE SUBTROPICAL RIDGE FOR THE
NEXT COUPLE OF DAYS...ALTHOUGH SOME ERRATIC MOTION IS POSSIBLE IN
THE SHORT TERM GIVEN THE POOR DEFINITION OF THE CIRCULATION...
INTERACTION WITH LAND...AND POTENTIAL REFORMATION OF THE CENTER.
THE OFFICIAL FORECAST FOLLOWS A BLEND OF THE GFS AND ECMWF
SOLUTIONS FOR THE 850 MB VORTICITY CENTER. TOWARD THE END OF THE
FORECAST PERIOD...ANA OR ITS REMNANTS COULD BE EMBEDDED WITHIN WEAK
STEERING OVER OR NEAR THE GULF OF MEXICO...AND THE OFFICIAL
FORECAST CALLS FOR A GRADUAL SLOWING OF THE FORWARD SPEED.

THE INTENSITY FORECAST IS COMPLICATED BY THE UNCERTAIN EXISTENCE OF
AN ACTUAL TROPICAL CYCLONE...THE LAND MASSES IN THE PATH OF THE
SYSTEM...AND HIGHLY DIVERGENT OBJECTIVE GUIDANCE. THE ENVIRONMENT
OF ANA IS STILL CHARACTERIZED BY SOUTHWESTERLY SHEAR. THE DYNAMICAL
MODELS...BOTH GLOBAL AND REGIONAL...ALMOST UNANIMOUSLY DISSIPATE
THE CYCLONE...WHILE THE STATISTICAL MODELS SHOW RESTRENGHENING. IF
ANA SURVIVES ITS PATH OVER THE GREATER ANTILLES AND EMERGES TO THE
NORTH OF THE DOMINICAN REPUBLIC...THE GLOBAL MODELS SUGGEST THAT A
MORE FAVORABLE UPPER WIND PATTERN WILL BE PRESENT THERE.
CONSEQUENTLY...THE OFFICIAL FORECAST MAINTAINS ANA AS A TROPICAL
CYCLONE THROUGH THE FORECAST PERIOD. THIS IS...ADMITTEDLY...
SOMETHING OF A HEDGE BETWEEN TWO MORE LIKELY ALTERNATIVES...THAT OF
A TROPICAL STORM NORTH OF THE ISLANDS OR IMMINENT DISSIPATION.


FORECAST POSITIONS AND MAX WINDS

INITIAL 17/1500Z 17.3N 66.2W 30 KT
12HR VT 18/0000Z 18.6N 69.4W 30 KT...INLAND
24HR VT 18/1200Z 20.5N 73.7W 30 KT
36HR VT 19/0000Z 22.3N 77.0W 30 KT
48HR VT 19/1200Z 23.7N 79.4W 30 KT
72HR VT 20/1200Z 26.5N 82.5W 30 KT
96HR VT 21/1200Z 28.0N 83.0W 30 KT
120HR VT 22/1200Z 30.0N 83.0W 25 KT...INLAND

$$
FORECASTER FRANKLIN/CANGIALOSI

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buoy just west of the storm, pressure is 998 and falling quick.

in motion it wobbles left of the last frame and a tiny eye was apparent 2nd to last frame.
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ANA DISCUSSION

000
WTNT42 KNHC 171500
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER 22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
1100 AM AST MON AUG 17 2009

THE CENTER OR WAVE AXIS OF ANA PASSED OVER BUOY 42060 AROUND
0830Z...AND IF A CENTER EXISTED AT THAT TIME IT WAS SOUTH OF THE
BUOY. THERE WAS ONE SHIP REPORT WITH A LIGHT WEST WIND AT 12Z.
SINCE THAT TIME...NEW CONVECTION WITH A MID-LEVEL SPIN HAS
DEVELOPED NEAR THE SOUTHEAST COAST OF PUERTO RICO. GIVEN THESE
HINTS...WE WILL CONTINUE ADVISORIES AT LEAST UNTIL A RECONNAISSANCE
AIRCRAFT INVESTIGATES ANA THIS AFTERNOON.

WITH A CENTER POSITION ESTIMATE BASED ON A BLEND OF CONTINUITY AND
THE MID-LEVEL ROTATION SEEN IN THE RADAR DATA...THE INITIAL MOTION
IS 285/24. ANA IS EXPECTED TO CONTINUE ON A GENERAL WEST-
NORTHWESTWARD TRACK TO THE SOUTH OF THE SUBTROPICAL RIDGE FOR THE
NEXT COUPLE OF DAYS...ALTHOUGH SOME ERRATIC MOTION IS POSSIBLE IN
THE SHORT TERM GIVEN THE POOR DEFINITION OF THE CIRCULATION...
INTERACTION WITH LAND...AND POTENTIAL REFORMATION OF THE CENTER.
THE OFFICIAL FORECAST FOLLOWS A BLEND OF THE GFS AND ECMWF
SOLUTIONS FOR THE 850 MB VORTICITY CENTER. TOWARD THE END OF THE
FORECAST PERIOD...ANA OR ITS REMNANTS COULD BE EMBEDDED WITHIN WEAK
STEERING OVER OR NEAR THE GULF OF MEXICO...AND THE OFFICIAL
FORECAST CALLS FOR A GRADUAL SLOWING OF THE FORWARD SPEED.

THE INTENSITY FORECAST IS COMPLICATED BY THE UNCERTAIN EXISTENCE OF
AN ACTUAL TROPICAL CYCLONE...THE LAND MASSES IN THE PATH OF THE
SYSTEM...AND HIGHLY DIVERGENT OBJECTIVE GUIDANCE. THE ENVIRONMENT
OF ANA IS STILL CHARACTERIZED BY SOUTHWESTERLY SHEAR. THE DYNAMICAL
MODELS...BOTH GLOBAL AND REGIONAL...ALMOST UNANIMOUSLY DISSIPATE
THE CYCLONE...WHILE THE STATISTICAL MODELS SHOW RESTRENGHENING. IF
ANA SURVIVES ITS PATH OVER THE GREATER ANTILLES AND EMERGES TO THE
NORTH OF THE DOMINICAN REPUBLIC...THE GLOBAL MODELS SUGGEST THAT A
MORE FAVORABLE UPPER WIND PATTERN WILL BE PRESENT THERE.
CONSEQUENTLY...THE OFFICIAL FORECAST MAINTAINS ANA AS A TROPICAL
CYCLONE THROUGH THE FORECAST PERIOD. THIS IS...ADMITTEDLY...
SOMETHING OF A HEDGE BETWEEN TWO MORE LIKELY ALTERNATIVES...THAT OF
A TROPICAL STORM NORTH OF THE ISLANDS OR IMMINENT DISSIPATION.


FORECAST POSITIONS AND MAX WINDS

INITIAL 17/1500Z 17.3N 66.2W 30 KT
12HR VT 18/0000Z 18.6N 69.4W 30 KT...INLAND
24HR VT 18/1200Z 20.5N 73.7W 30 KT
36HR VT 19/0000Z 22.3N 77.0W 30 KT
48HR VT 19/1200Z 23.7N 79.4W 30 KT
72HR VT 20/1200Z 26.5N 82.5W 30 KT
96HR VT 21/1200Z 28.0N 83.0W 30 KT
120HR VT 22/1200Z 30.0N 83.0W 25 KT...INLAND

$$
FORECASTER FRANKLIN/CANGIALOSI
000
WTNT42 KNHC 171500
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER 22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
1100 AM AST MON AUG 17 2009

THE CENTER OR WAVE AXIS OF ANA PASSED OVER BUOY 42060 AROUND
0830Z...AND IF A CENTER EXISTED AT THAT TIME IT WAS SOUTH OF THE
BUOY. THERE WAS ONE SHIP REPORT WITH A LIGHT WEST WIND AT 12Z.
SINCE THAT TIME...NEW CONVECTION WITH A MID-LEVEL SPIN HAS
DEVELOPED NEAR THE SOUTHEAST COAST OF PUERTO RICO. GIVEN THESE
HINTS...WE WILL CONTINUE ADVISORIES AT LEAST UNTIL A RECONNAISSANCE
AIRCRAFT INVESTIGATES ANA THIS AFTERNOON.

WITH A CENTER POSITION ESTIMATE BASED ON A BLEND OF CONTINUITY AND
THE MID-LEVEL ROTATION SEEN IN THE RADAR DATA...THE INITIAL MOTION
IS 285/24. ANA IS EXPECTED TO CONTINUE ON A GENERAL WEST-
NORTHWESTWARD TRACK TO THE SOUTH OF THE SUBTROPICAL RIDGE FOR THE
NEXT COUPLE OF DAYS...ALTHOUGH SOME ERRATIC MOTION IS POSSIBLE IN
THE SHORT TERM GIVEN THE POOR DEFINITION OF THE CIRCULATION...
INTERACTION WITH LAND...AND POTENTIAL REFORMATION OF THE CENTER.
THE OFFICIAL FORECAST FOLLOWS A BLEND OF THE GFS AND ECMWF
SOLUTIONS FOR THE 850 MB VORTICITY CENTER. TOWARD THE END OF THE
FORECAST PERIOD...ANA OR ITS REMNANTS COULD BE EMBEDDED WITHIN WEAK
STEERING OVER OR NEAR THE GULF OF MEXICO...AND THE OFFICIAL
FORECAST CALLS FOR A GRADUAL SLOWING OF THE FORWARD SPEED.

THE INTENSITY FORECAST IS COMPLICATED BY THE UNCERTAIN EXISTENCE OF
AN ACTUAL TROPICAL CYCLONE...THE LAND MASSES IN THE PATH OF THE
SYSTEM...AND HIGHLY DIVERGENT OBJECTIVE GUIDANCE. THE ENVIRONMENT
OF ANA IS STILL CHARACTERIZED BY SOUTHWESTERLY SHEAR. THE DYNAMICAL
MODELS...BOTH GLOBAL AND REGIONAL...ALMOST UNANIMOUSLY DISSIPATE
THE CYCLONE...WHILE THE STATISTICAL MODELS SHOW RESTRENGHENING. IF
ANA SURVIVES ITS PATH OVER THE GREATER ANTILLES AND EMERGES TO THE
NORTH OF THE DOMINICAN REPUBLIC...THE GLOBAL MODELS SUGGEST THAT A
MORE FAVORABLE UPPER WIND PATTERN WILL BE PRESENT THERE.
CONSEQUENTLY...THE OFFICIAL FORECAST MAINTAINS ANA AS A TROPICAL
CYCLONE THROUGH THE FORECAST PERIOD. THIS IS...ADMITTEDLY...
SOMETHING OF A HEDGE BETWEEN TWO MORE LIKELY ALTERNATIVES...THAT OF
A TROPICAL STORM NORTH OF THE ISLANDS OR IMMINENT DISSIPATION.
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Is it no 11am track change or Ana?
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Quoting MrSea:
anyone seen the NAM??? compared to the 6z run, the 12z run has a much stronger high offshore, which would stop it from going out to sea


6z


12z
hold on, explain to me what is happening?
It seems, based on the NHC discussion, that they are really counting the possibilities that could happen with Ana.
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Quoting taistelutipu:
Thanks Patrap, I've had a look at this one now. If Bill intensifies further than he could actually turn towards the weakness. The higher steering layers for stronger storms show that possibility. Ok, so now I can see what StormW meant in his prediction about Bill's possible movement. Cool, thanks!


Anytime,there are lotsa folks here who can answer most Questions or direct you to a source for an answer to most.

Thats why we blog.
Member Since: July 3, 2005 Posts: 423 Comments: 127902
lol drak said 2 days ago that BILL was a pretty safe bet it was going to S Florida.... OMG!
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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