Atlantic Tropical Storm Karen

[Iceberg]

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007

1100 PM EDT MON SEP 24 2007

THE LARGE LOW PRESSURE AREA IN THE EASTERN ATLANTIC HAS ACQUIRED

ENOUGH ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A

2004 UTC QUIKSCAT OVERPASS WAS HELPFUL IN LOCATING THE CENTER OF

THE DEPRESSION AND THE QUIKSCAT DATA SUGGEST THAT THE MAXIMUM WINDS

WERE AROUND 25 KT AT THAT TIME. SINCE THEN...DEEP CONVECTION

HAS INCREASED NEAR THE CENTER AND DVORAK CLASSIFICATIONS FROM TAFB

AND SAB SUPPORT TROPICAL STORM STRENGTH. HOWEVER...THERE WAS SOME

SPREAD IN THE CENTER LOCATION OF THESE ESTIMATES...SO THE INITIAL

INTENSITY IS SET AT 30 KT.

THE INITIAL MOTION ESTIMATE IS 285/14. THE DEPRESSION IS EXPECTED TO

CONTINUE MOVING WEST-NORTHWESTWARD SOUTH OF A MID-LEVEL RIDGE OVER

THE CENTRAL AND EASTERN ATLANTIC DURING THE NEXT FEW DAYS. A

WEAKNESS IN THE RIDGE IS FORECAST TO DEVELOP OVER THE CENTRAL

ATLANTIC IN 4 OR 5 DAYS...WHICH SHOULD ALLOW FOR A NORTHWESTWARD

TURN LATER IN THE FORECAST PERIOD. THE DYNAMICAL MODEL GUIDANCE

GENERALLY AGREES ON THIS SCENARIO...BUT THERE IS SOME SPREAD IN

HOW FAR WEST THE CYCLONE WILL BE WHEN THE TURN MATERIALIZES. THE

GFS...AND GFDL ARE FARTHER WEST...WHILE THE NOGAPS AND ECMWF ARE

ALONG THE EASTERN SIDE OF THE GUIDANCE. THE OFFICIAL FORECAST IS

ALONG THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE AND LEANS CLOSER

TO THE GFS/GFDL SOLUTIONS.

THE INTENSITY FORECAST IS SOMEWHAT PROBLEMATIC. THE DEPRESSION

APPEARS TO BE IN A FAVORABLE ENVIRONMENT FOR STRENGTHENING DURING

THE NEXT COUPLE OF DAYS. THE SHIPS MODEL BRINGS THE DEPRESSION TO

HURRICANE STATUS IN 48 HOURS WHILE THE DYNAMICAL MODEL GUIDANCE IS

LESS AGGRESSIVE DURING THIS TIME FRAME. BEYOND 72 HOURS...THE

GLOBAL MODELS INDICATE THAT SOUTH TO SOUTHWESTERLY SHEAR WILL

INCREASE...WHICH SHOULD HALT ADDITIONAL STRENGTHENING. THE

OFFICIAL INTENSITY FORECAST IS MORE CONSERVATIVE THAN THE SHIPS

GUIDANCE AND IS CLOSER TO THE GFDL INTENSITY FORECAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL 25/0300Z 10.1N 36.2W 30 KT

12HR VT 25/1200Z 10.6N 38.4W 35 KT-

24HR VT 26/0000Z 11.2N 41.4W 45 KT

36HR VT 26/1200Z 11.8N 44.5W 50 KT

48HR VT 27/0000Z 12.5N 47.4W 55 KT

72HR VT 28/0000Z 15.3N 50.9W 60 KT

96HR VT 29/0000Z 19.0N 53.0W 60 KT

120HR VT 30/0000Z 22.0N 54.5W 60 KT

Edited September 25, 2007 by Iceberg

[Iceberg]

A few more bits.

Convection is very much centering now, and she is a large storm.

Path and GFDL attached. Don't expect her to get above a CAT 3, temps(Ocean heat content) just arn't high enough in her path IMO.

Longer term it all depends on when she turns northwards and where the Blocking Atlantic high situates itself. GFS again gets her in the westerlies in 10-13 days time. But is not very good at handling these situations at all. ECM will be the one to watch.

Might she effect October for us.......

[Somerset Squall]

The depression has strengthened to Tropical Storm Karen. We could see a hurricane out of this one- but the conservative NHC are calling for it to fall just below strength at peak. Karen has good conditions ahead of her but complications arise later in the forecast period regarding two troughs approaching Karen- it's not entirely clear what impact they will have on her.

TROPICAL STORM KAREN DISCUSSION NUMBER 2

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007

500 AM EDT TUE SEP 25 2007

SATELLITE IMAGERY INDICATES THAT TROPICAL DEPRESSION TWELVE HAS

CONTINUED TO GRADUALLY ORGANIZE...WITH INCREASED CONVECTIVE BANDING

OVER A LARGE AREA SURROUNDING THE CENTER. SATELLITE INTENSITY

ESTIMATES FROM TAFB AND SAB ARE AGAIN 35 KT...SO THE DEPRESSION IS

UPGRADED TO TROPICAL STORM KAREN.

THE INITIAL MOTION REMAINS 285/14. KAREN IS ON THE SOUTH SIDE OF A

LOW/MID-LEVEL RIDGE...WHICH SHOULD STEER THE CYCLONE FOR THE NEXT

36-48 HR. AFTER THAT...THE LARGE-SCALE MODELS AGREE ON THE

DEVELOPMENT OF A MID/UPPER-LEVEL TROUGH TO THE NORTHEAST OF THE

LESSER ANTILLES...WHICH WOULD TURN KAREN NORTHWESTWARD OR

NORTHWARD. THERE IS SOME SPREAD IN THE GUIDANCE...WITH THE

GFDL...HWRF...ANND ECMWF SHOWING A NORTHWARD MOTION BETWEEN

50W-53W...WHILE THE UKMET AND GFS ENSEMBLE MEAN SHOW A

NORTHWESTWARD MOTION TO WEST OF 56W BY 120 HR. SINCE THERE IS

OFTEN A TENDENCY FOR THE DYNAMICAL MODELS TO HAVE A NORTHWARD BIAS

IN THE TROPICAL ATLANTIC...THE NEW FORECAST TRACK IS ALONG THE

SOUTH EDGE OF THE MODEL GUIDANCE FOR THE FIRST 72 HR...AND THEN TO

THE LEFT OF CENTER OF THE GUIDANCE ENVELOPE THEREAFTER.

THE INTENSITY FORECAST...IF ANYTHING...HAS BECOME MORE PROBLEMATIC.

KAREN IS CURRENTLY IN AN ENVIRONMENT OF LIGHT NORTHWESTERLY VERTICAL

WIND SHEAR...WHICH SHOULD CONTINUE FOR 24-36 HR. AFTER THAT...AN

UPPER-LEVEL TROUGH IS FORECAST TO DEVELOP VERY CLOSE TO THE STORM

TRACK...FOLLOWED BY THE DEVELOPMENT OF THE MID/UPPER-LEVEL TROUGH

MENTIONED ABOVE. THE LARGE-SCALE MODELS FORECAST THE FIRST TROUGH

TO CAUSE BOTH STRONG UPPER-LEVEL DIFLUENCE AND SHEAR OVER KAREN...

AND IT IS UNCLEAR AT THIS TIME WHETHER THIS SYSTEM WOULD CAUSE THE

STORM TO INTENSIFY OR WEAKEN. THE SECOND TROUGH IS FORECAST TO

CAUSE SIGNIFICANT SHEAR WITHOUT STRONG DIFLUENCE...WHICH SHOULD

CAUSE WEAKENING. THE SHIPS...GFDL...AND HWRF MODELS ALL FORECAST

KAREN TO BECOME A HURRICANE BY 60-72 HR. GIVEN THE UNCERTAINTY IN

THE STRENGTH OF THE SHEAR...THE INTENSITY FORECAST CALLS FOR KAREN

TO PEAK JUST BELOW HURRICANE STRENGTH...FOLLOWED BY WEAKENING DUE

TO SHEAR FROM THE SECOND TROUGH.

FORECAST POSITIONS AND MAX WINDS

INITIAL 25/0900Z 10.4N 38.0W 35 KT

12HR VT 25/1800Z 10.8N 40.0W 40 KT

24HR VT 26/0600Z 11.3N 43.0W 45 KT

36HR VT 26/1800Z 11.8N 45.7W 55 KT

48HR VT 27/0600Z 12.9N 47.9W 60 KT

72HR VT 28/0600Z 16.0N 51.0W 60 KT

96HR VT 29/0600Z 19.0N 53.0W 55 KT

120HR VT 30/0600Z 22.0N 54.5W 55 KT

$$

FORECASTER BEVEN

[kold weather]

Its interesting to see the size of this system, certainly not a small one!

Convection is still very broad and the circulation still appears fairly broad but there does appear to be banding present with it and Sat.estimates suggests the system is now at 40kts though i'm not sure if quikscat backs that up or not, haven't been able to see it.

models are forecasting this system to reach hurricane strength though the NHC are being conservative due to the models increasing shear levels beyond 72hrs as the system heads northwards. I suspect the NHc are covering themselves however i think given its current set-up 75-80kts is perfectly possible and the waters easily support that. What happens after that is dependant on whether the shear increases like forecasted (as the models aren't amazing at forecasting shear past 72hrs it has to be said) and also exactly where it track is. The further north it gets by 72hrs the greater the shear will be on this system and the trend of the NHC may not be far wrong though i think they are a little low for max strength. IF it doesn't lift out as much as forecasted then shear won't be as high as the NHC forecasts which wil probably mean Karen wil hold its strength.

Its track still looks very fish like to me and the models stil lturn this system towards the north by 72-96hrs as a weakness opens up. The 12z GFS though has this system a good deal further west then its 06z run, not that much different to the very westerly UKMO. Doubt it'll be a USA threat but Ne Caribbean may feel some effects from it and while it'll be unlucky, Bermuda may need to watch just in case as well as I think it probably may get west enough at one point in the systems lifespan.

Going to be a long one this one, unless shear really destroys it in the future, going to be a 7-10 day system to track...

[Iceberg]

This one will keep us going for ages.

Track is changing bit by bit, both ECM and GFS tend towards a possible US strike now Approx 15 days away !. This one could keep going for half a month.

[Somerset Squall]

Karen has strengthened further and is almost a hurricane. Intensification will slow from now as shear is increasing and Karen is forecasted to weaken beyond day 3 as shear becomes even stronger.

TROPICAL STORM KAREN DISCUSSION NUMBER 7

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007

1100 AM EDT WED SEP 26 2007

KAREN CONTINUES TO SPIN UP AS A RAGGED EYE HAS BEEN SEEN

INTERMEDITENTLY THIS MORNING IN VISIBLE AND INFRARED IMAGERY.

SUBJECTIVE DVORAK CLASSIFICATIONS AT 12Z ARE AT 4.0 AND 3.5 FROM

TAFB AND SAB...RESPECTIVELY. AN AMSU PASS AT 08Z SUGGESTED AROUND

60 KT FROM THE CIMSS TECHNIQUE. THE ADT...HOWEVER...ANALYSES KAREN

A BIT WEAKER AT ABOUT 50 KT. GIVEN THE IMPROVED PRESENTATION SINCE

SYNOPTIC TIME...THE INITIAL INTENSITY OF KAREN IS SET AT 60 KT.

THE TROPICAL STORM IS MOVING AT 285/11 SOUTH OF A WEAK DEEP LEVEL

RIDGE. AN UPPER TROUGH NORTHWEST OF KAREN IS FORECAST BY ALL

MODELS TO SLOWLY RETROGRADE AND PRODUCE ENOUGH OF A WEAKNESS IN THE

RIDGE TO ALLOW THE CYCLONE TO TURN TO THE NORTHWEST. THE MODEL

GUIDANCE IS TIGHTLY CLUSTERED FOR THE FIRST 48 HOURS. AT DAYS 3 TO

5...MOST MODELS SLOW KAREN'S PROGRESSION AS THE STEERING FLOW

SLACKENS. THE MODELS DIFFER AT THE LONG RANGE ON BOTH THE STRENGTH

OF THE CYCLONE'S VORTEX AS WELL AS THE AMPLITUDE OF A SHORTWAVE

TROUGH NEAR BERMUDA. THE TRACK FORECAST IS CLOSE TO THE CONSENSUS

OF DYNAMICAL MODELS WITH LESS WEIGHT BEING PLACED ON THE NORTHERN

OUTLYING NOGAPS MODEL.

GIVEN THAT THE CYCLONE IS INTENSIFYING...IT APPEARS THAT IT MAY

REACH HURRICANE INTENSITY SOON. ENVIRONMENTAL CONDITIONS ARE

MIXED. SSTS ARE A WARM 28C THOUGH THE SHEAR IS ANALYZED TO BE

ABOUT 15 KT OUT OF THE WEST. THIS SHEAR DOES APPEAR TO BE

RESTRICTING THE WESTERN OUTFLOW OF KAREN. THE SHEAR IS PREDICTED

BY ALL MODELS TO BE MAINTAINED OR EVEN GET STRONGER AT DAYS 3 TO 5

DUE TO THE INFLUENCE OF THE EARLIER MENTIONED UPPER LEVEL TROUGH.

THE INTENSITY FORECAST BRINGS KAREN TO A HURRICANE SHORTLY...

LEVELING OFF IN A DAY OR TWO...AND THEN WEAKENING AT DAYS 4 AND 5.

THIS IS IN AGREEMENT WITH SHIPS AND LGEM BUT STRONGER THAN HWRF AND

GFDL WHICH DO NOT BRING KAREN TO HURRICANE INTENSITY.

FORECAST POSITIONS AND MAX WINDS

INITIAL 26/1500Z 11.9N 42.9W 60 KT

12HR VT 27/0000Z 12.6N 44.5W 65 KT

24HR VT 27/1200Z 14.0N 46.8W 75 KT

36HR VT 28/0000Z 15.5N 48.5W 75 KT

48HR VT 28/1200Z 16.8N 50.0W 70 KT

72HR VT 29/1200Z 19.0N 52.0W 65 KT

96HR VT 30/1200Z 21.0N 54.0W 60 KT

120HR VT 01/1200Z 23.0N 55.5W 55 KT

$$

FORECASTER LANDSEA/PASCH

[kold weather]

Looks very close to hurricane status right now with a eyewall seemingly forming. There are outflow boundaries coming from the SW quadrant which will probably prevent hurricane status for another 12-24hrs but it seems thats an eventual outcome of this system. Track still looks like its going out to sea but you can't ignore the ECM which sends it back W at 192hrs as an upper high forms to its north...hard to forecast its exact track right now other then for now its heading W/WNW and its going to be a long tracker.

[Iceberg]

Interesting update from NHC. Not sure I agree with it though. The path has been much more northerly than suggested by NHC, indeed it's considerably off it's path now. This has ment that the centre is again away from the worse of the Shear although outflow is very limited in the SW quad. A strong 60KT strom could well continue for 4 or 5 day and if the new path is realised/maintained then a further spell of strengthening could occur in 5 days time or so.

Some deep convection rotating around the centre at the moment.

A NOAA HURRICANE HUNTER PLANE HAS BEEN CONDUCTING A RESEARCH MISSION

THIS EVENING AND HAS FOUND AN UNUSUAL WIND STRUCTURE WITH KAREN.

SFMR DATA SHOW THAT THE STORM HAS A VERY LARGE WIND FIELD...WITH

ONE PEAK IN SURFACE WINDS ABOUT 105 NM AWAY FROM THE CENTER AND

ANOTHER ONE AT A MORE TYPICAL DISTANCE. IN ADDITION...DROPSONDE AND

SFMR DATA SUGGEST THAT THE FLIGHT LEVEL CENTER IS DISPLACED TO THE

NORTH AND EAST OF THE SURFACE CENTER...LIKELY DUE TO SOUTHWESTERLY

WIND SHEAR. THE MAXIMUM FLIGHT LEVEL WIND REPORTED WAS 69 KT...WITH

A PEAK SURFACE VALUE OF 62 KT REPORTED TWICE...NOT QUITE HURRICANE

STRENGTH. HOWEVER...GIVEN THE DEGRADED SATELLITE APPEARANCE FROM

EARLIER TODAY...KAREN WAS ALMOST CERTAINLY A HURRICANE THEN...AND

THIS LIKELIHOOD MAY BE REFLECTED IN THE FINAL BEST TRACK FOR THE

SYSTEM. AT THIS TIME...THE INITIAL INTENSITY IS HELD AT 60 KT FOR

THIS ADVISORY.

MODERATE TO STRONG SOUTHWESTERLY SHEAR FROM THE MID-OCEANIC TROUGH

IS AFFECTING KAREN AND THIS SHEAR IS FORECAST TO PERSIST OR EVEN

INTENSIFY OVER THE NEXT SEVERAL DAYS. IT IS HARD TO FORECAST

ANYTHING BUT SLOW WEAKENING GIVEN SUCH AN UNFAVORABLE ENVIRONMENT

AHEAD OF THE STORM...AND KAREN'S CHANCE TO INTENSIFY HAS PROBABLY

ENDED. INITIALLY...MOST MODELS DO NOT WEAKEN THE SYSTEM VERY

MUCH...PERHAPS DUE TO THE LARGE STORM BEING ABLE TO MAINTAIN ITSELF

DESPITE THE SHEAR. EVENTUALLY...MOST INTENSITY GUIDANCE WEAKEN THE

SYSTEM...AND THE OFFICIAL FORECAST IS CLOSER TO THE HWRF/GFDL

MODELS THAN THE SHIPS MODEL. IT IS OF NOTE THAT THE GFDL EVEN

MAKES THIS SYSTEM A TROPICAL DEPRESSION BY THE END OF THE FORECAST.

MICROWAVE AND AIRCRAFT DATA HAVE PROVIDED A GOOD ESTIMATE OF THE

INITIAL MOTION...ABOUT 300/12. THIS GENERAL MOTION SHOULD CONTINUE

FOR THE NEXT DAY OR SO AS WEAK RIDGING PERSISTS TO THE NORTH OF THE

STORM. STEERING CURRENTS THEN WEAKEN AS A MIDDLE TO UPPER-LEVEL

TROUGH CREATES A WEAKNESS IN THE RIDGE. THE MODELS THAT HAVE A

STRONG...VERTICALLY-STACKED REPRESENTATION OF KAREN...E.G. THE

ECMWF/GFDN/HWRF/NOGAPS SOLUTIONS..SHOW THE STORM MOVING MORE TO THE

NORTHWEST OR NORTH-NORTHWEST IN RESPONSE TO THE TROUGH. HOWEVER

THE GFDL/GFS/UKMET MODELS GENERALLY HAVE A WEAKER STORM AT THAT

TIME...AND SHOW LITTLE REACTION TO THE TROUGH AND JUST SLOW THE

STORM AS IT ENTERS THE AREA OF LIGHTER STEERING CURRENTS. THE

OFFICIAL FORECAST FAVORS THE LEFTWARD SOLUTION AT THIS TIME AND IS

ADJUSTED WESTWARD OF THE PREVIOUS FORECAST.

THE WIND RADII WERE EXPANDED THANKS TO SFMR DATA...QUIKSCAT...AND

NOAA BUOY 41041.

FORECAST POSITIONS AND MAX WINDS

INITIAL 27/0300Z 13.0N 45.1W 60 KT

12HR VT 27/1200Z 13.9N 46.7W 60 KT

24HR VT 28/0000Z 15.2N 48.7W 60 KT

36HR VT 28/1200Z 16.5N 50.5W 55 KT

48HR VT 29/0000Z 17.5N 51.9W 50 KT

72HR VT 30/0000Z 19.4N 54.7W 45 KT

96HR VT 01/0000Z 21.0N 57.0W 45 KT

120HR VT 02/0000Z 22.5N 58.5W 45 KT

[kold weather]

Interestingly Iceberg I don't really agree with you on this one. The more northerly it gets the stronger the shear is going to become and this is starting to show now as the center is now located on the far SW area of convection. Recon fixed the center on the Sw side of the convection and since then shear has increased and so the center has become even more displaced.

Probably already in a weakening phase and if the shear doesn't ease off soon the convection will soon start to weaken and the system wil weaken pretty rapidly with it.

In the long term if it can survive then come 3-4 days time then the shear may well ease off again, will be interesting to watch.

[Somerset Squall]

Karen is continuing to weaken with an intial intensity of 50 knots, which may be a little generous. Karen was looking very poor earlier with the center fully exposed and the convection far away to the northeast and even that wasn't deep. But there has been a pretty deep flare up of convection over the centre now which has saved Karen because she really looked like she was on her last legs earlier.

The NHC continue to forecast weakening, but mention that shear could ease after day 4 which may allow for reintensification. If Karen can fight and survive that long then conditions do look more favourable but if Karen has many more convective lapses it may end up the same way as Ingrid IMO.

Here's the latest discussion:

TROPICAL STORM KAREN DISCUSSION NUMBER 12

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007

500 PM EDT THU SEP 27 2007

PERSISTENTLY STRONG SOUTHWESTERLY SHEAR CONTINUES TO AFFECT THE

TROPICAL CYCLONE...DISPLACING THE DEEP CONVECTION FROM THE

CIRCULATION CENTER. ALTHOUGH DVORAK SATELLITE INTENSITY ESTIMATES

FROM TAFB AND SAB HAVE DECREASED TO 45 KT...SOME RECENT DEEP

CONVECTIVE BURSTS NEAR THE CENTER SUGGEST A SLIGHTLY HIGHER

INTENSITY. THEREFORE...THE INITIAL WIND SPEED IS SET TO 50 KT.

THE INTENSITY FORECAST IS RELATIVELY STRAIGHTFORWARD THROUGH DAY

5...INDICATING GRADUAL WEAKENING. HOWEVER...LARGE-SCALE DYNAMICAL

MODELS...SHIPS...AND THE LGEM ARE NOW SUGGESTING THAT THE SHEAR

WILL BEGIN TO WEAKEN AROUND THE 96 TO 120 HR PERIOD WHEN THE

TROPICAL CYCLONE REACHES THE UPPER TROUGH AXIS. CONSEQUENTLY...

SLIGHT INTENSIFICATION IN THE LATTER PART OF THE PERIOD IS

POSSIBLE...ALBEIT NOT INDICATED IN THE OFFICIAL FORECAST AT THIS

TIME.

KAREN IS MOVING AT 305/11...WITH THIS GENERAL MOTION CONTINUING

DURING THE NEXT 2 DAYS OR SO AS KAREN PROPAGATES WITHIN THE

DEEP-LAYERED FLOW ASSOCIATED WITH THE SUBTROPICAL RIDGE TO THE

NORTH. THROUGH THE REMAINING PORTION OF THE FORECAST...THE

DYNAMICAL MODELS ARE AGREEING IN BUILDING THE MID- LEVEL RIDGE MORE

TOWARD THE NORTHWEST OF THE CYCLONE CAUSING KAREN TO TURN MORE

WEST-NORTHWESTWARD. THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS

PACKAGE AND IS BASED ON A CONSENSUS OF THE MODELS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 27/2100Z 14.3N 48.5W 50 KT

12HR VT 28/0600Z 15.5N 49.8W 45 KT

24HR VT 28/1800Z 16.8N 51.5W 45 KT

36HR VT 29/0600Z 17.8N 52.8W 45 KT

48HR VT 29/1800Z 18.7N 54.0W 45 KT

72HR VT 30/1800Z 20.5N 55.5W 40 KT

96HR VT 01/1800Z 22.5N 56.5W 40 KT

120HR VT 02/1800Z 24.0N 58.5W 40 KT

$$

FORECASTER ROBERTS/AVILA

I suppose Karen's size may help her cope with the shear a little better than Ingrid did?

Edited September 27, 2007 by Somerset Squall

[parmenides3]

I also notice some build up on a line around 25W, which might become an invest or system in the next 24 hours... what name is after Lorenzo?

And a reminder for anyone who doesn't already have this link on their bookmarks:

http://www.crownweather.com/tropical.html#atlantic

:)P

Edited September 27, 2007 by parmenides3

[Iceberg]

We all knew we were in for a long time watch with her.

Shear is stil taking a toll, although to have that amount of convection under 40-50Kt shear is pretty impressive. Yesterday the LLCC was almost entirely exposed, but this revealed that it was a very very good solid LLCC.

Both GFDL and HWRF take Karen back up to near Hurricane strength at the end of the runs and it seems that a further period of intenisification will begin in approx 4 days time.

Interesting ECM from yesterday and certainly not to be discounted as it's ran with Karen from the outset a Serious Florida hit. This is moving further and futher south and re-entry into the GOM is not out of the question either.

Edited September 28, 2007 by Iceberg

[Somerset Squall]

I also notice some build up on a line around 25W, which might become an invest or system in the next 24 hours... what name is after Lorenzo?

P

Melissa is the next name. The NHC hints at it for development.

[Somerset Squall]

Karen has weakened further to 35kts and once again the NHC says this could be generous. The shear is now forecast to persist longer than originally anticipated and condtions look unfavourable in Karen's track. Strengthening is no longer anticipated and we could well see Karen dissapate very soon.

[kold weather]

Karen looks a goner this morning, I can't find a center right now which suggests its not a tropical system anymore. Will have to wait for another few hours for the Vis.images to get updated but it doesn't look good for Karen right now.

By the way at the end of the season Karen will be upgraded to a hurricane post-season, discussion from an earlier forecast makes that pretty clear.

Edit---found the LLC but its totally exposed right now, unless the shear eases down in the next 12-24hrs its got only a slim chance of surviving.

Edited September 29, 2007 by kold weather

[Somerset Squall]

Karen has been downgraded to a tropical depression but it may not even be that. It's forecasted to be a remnant low within the next 12 hours. The main reason it's been kept as a tropical depression is because some of the guidance models still want to take Karen to hurricane status when the shear finally weakens. It does have a chance at regeneration after it dissapates.

[Somerset Squall]

Is it me or has the convection become more concentrated over the centre over the last few hours?

[Somerset Squall]

Karen is no longer a tropical cyclone. Regeneration could occur over the next few days.

TROPICAL DEPRESSION KAREN DISCUSSION NUMBER 20

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007

500 PM EDT SAT SEP 29 2007

THE SHEAR HAS BEATEN KAREN. SATELLITE IMAGES INDICATE THAT KAREN NO

LONGER HAS A WELL-DEFINED CENTER AND BASICALLY DOES NOT QUALIFY AS A

TROPICAL DEPRESSION. HOWEVER...THERE IS STILL A BROAD AREA OF LOW

PRESSURE WITH STRONG SQUALLS IN A FEW CONVECTIVE BANDS OVER THE

EASTERN HALF OF THE CIRCULATION. THE BROAD AREA OF LOW PRESSURE...

OR THE REMNANTS OF KAREN...ARE EXPECTED TO CONTINUE MOVING TOWARD

THE NORTHWEST OR 315 DEGREES AT 8 KNOTS.

AT THIS POINT...I AM NOT GOING TO SPECULATE IF KAREN IS GOING TO

REGENERATE OR NOT. MODELS HAVE THE LUXURY OF GOING BACK AND FORTH

IN STRENGTHENING OR WEAKENING KAREN IN EACH RUN...BUT I DON'T. THE

BEST WE CAN DO IS TO MONITOR THE SYSTEM CLOSELY...AND IF IT COMES

BACK...WHICH IS NOT OUT OF THE QUESTION...REINITIATE ADVISORIES.

FOR NOW...THIS IS THE LAST ADVISORY ON KAREN. ADDITIONAL

INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS

FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER AWIPS

HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/2100Z 17.3N 54.3W 30 KT

12HR VT 30/0600Z 18.0N 55.5W 25 KT...REMNANT LOW

24HR VT 30/1800Z...DISSIPATED

$$

FORECASTER AVILA