Ex Tropical Depression KAREN: Discussions & Images

[wxman57]

Couple of things:
1) Karen (such as she is) is definitely with the NW blob. The quickscat center is just south of that blob. For some reason (perhaps her size) it's a little easier to see things on the Central Atlantic loop and that matches the quickscat.
2) Highest winds, as usual, are associated with the convection. The convection is near the storm-relative center, which is north of the earth-relative center. I don't think that makes her non-tropical or an open wave.
3) If you look at the motion on the Central Atlantic loop it's clear that Karen is now moving *south* of due west (quite a change from this morning!) which is bad for her future existence since she's going to be in the shear indefintely.

I think some of you are seeing the illusion of an LLC. The south of west motion is the wave axis propagating westward and convection firing along it. Take a look at a WV loop and you'll see what I mean. There's a massive upper low just west of Karen and strong SW winds right over that burst of convection. The convection is moving southwestward right into the jet core and into the right rear of the upper low. There's no associated LLC.

One thing is absolutely certain - no one will be able to detect any LLC in Karen without visible imagery or surface obs. You just can't see the lower-level clouds well at night. We'll have to wait until morning to be sure if anything is left of Karen's LLC.

[cycloneye]

266
WTNT42 KNHC 290231
TCDAT2
TROPICAL STORM KAREN DISCUSSION NUMBER 17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007
1100 PM EDT FRI SEP 28 2007

DETERMINING THE ACTUAL CENTER OF KAREN HAS BEEN A SIGNIFICANT
CHALLENGE THIS EVENING. IT APPEARS THAT THE EARLIER EXPOSED
CENTER...NOW MOVING NORTHWESTWARD...HAS BECOME JUST ANOTHER SWIRL
AROUND AN ELONGATED LOW-LEVEL CIRCULATION FARTHER TO THE SOUTHWEST.
A RECENT QUIKSCAT PASS SUPPORTS THIS ASSESSMENT...SHOWING A LARGE
AREA OF LIGHT WINDS SOUTHWEST OF THE OLD CENTER. THUS...THE CENTER
IS RELOCATED WESTWARD TO THE LIGHTER WIND AREA AS SUGGESTED BY
QUIKSCAT AND NIGHT VISIBLE SATELLITE IMAGES. OVERALL..THE SYSTEM
REMAINS VERY DISORGANIZED DUE TO FEROCIOUS WESTERLY SHEAR...WITH
THUNDERSTORMS MOSTLY IN THE EASTERN SEMICIRCLE. EVEN WITH THE
DISHEVELED SATELLITE APPEARANCE...QUIKSCAT SUPPORTS AN INTENSITY OF
AT LEAST 35 KT...AND THE INITIAL INTENSITY WILL BE HELD AT 35 KT.

STRONG WESTERLY OR SOUTHWESTERLY SHEAR IS FORECAST TO CONTINUE FOR
ABOUT THE NEXT 48 HOURS AND SHOULD INDUCE WEAKENING OF KAREN. THE
INTENSITY FORECAST FOR THIS TIME SHOWS THE SYSTEM BARELY HANGING ON
AS A TROPICAL CYCLONE....AND DISSIPATION IS POSSIBLE.
THEREAFTER...THE GFS AND UKMET MODELS CARVE OUT A PIECE OF THE
MID-OCEANIC TROUGH INTO A CUT-OFF LOW THAT MOVES SOUTHWARD NEAR AND
THEN TO THE SOUTH OF WHATEVER REMAINS OF KAREN. THIS EVOLUTION
COULD PLACE THE SYSTEM IN A MORE FAVORABLE LOCATION FOR SOME
STRENGTHENING WITH MORE EASTERLY FLOW ALOFT TO THE NORTH OF THE
CUT-OFF LOW. THE GFDL RESPONDS TO THESE CONDITIONS BY MAKING KAREN
A HURRICANE IN ABOUT 4 DAYS. HOWEVER...OTHER MODELS KEEP MODERATE
TO STRONG SHEAR OVER THE SYSTEM FOR A LONGER PERIOD OF TIME AND
THIS SOLUTION WOULD FAVOR DISSIPATION. UNTIL THERE IS SOME CLARITY
ON IF THE SYSTEM WILL SURVIVE THE SHEAR...I'M INCLINED TO MAKE
LITTLE CHANGE TO THE LONG-TERM FORECAST AND KEEP THE CYCLONE AS A
TROPICAL DEPRESSION. OBVIOUSLY...FORECAST CONFIDENCE IS EXTREMELY
LOW TONIGHT.

TO SMOOTH OUT THE IRREGULAR MOTION DURING THE PAST 24 HOURS... A
LONG-TERM MOVEMENT WILL BE USED AS THE INITIAL MOTION...ESTIMATED
AT 295/8. A TRACK BETWEEN WEST-NORTHWEST AND NORTHWEST IS EXPECTED
FOR THE NEXT FEW DAYS AS KAREN MOVES AROUND THE SOUTHWESTERN SIDE
OF A LOW TO MID-LEVEL RIDGE OVER THE CENTRAL ATLANTIC OCEAN.
THEREAFTER A TURN TO A MORE WESTWARD MOTION IS POSSIBLE DUE TO
RISING HEIGHTS TO THE NORTH OF KAREN. NUMERICAL GUIDANCE HAS
BEEN MUCH TOO FAR TO THE RIGHT WITH THIS SYSTEM AND...GIVEN THE
CONTINUED WEAK INTENSITY OF THE STORM...THE NHC FORECAST WILL LIE
ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE SIMILAR TO THE 18Z GFS.
THE LARGE WESTWARD SHIFT AT 4 AND 5 DAYS IS MOSTLY DUE TO THE
CENTER REFORMATION...AND NOT A HUGE CHANGE IN THE MODEL GUIDANCE.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/0300Z 16.2N 51.9W 35 KT
12HR VT 29/1200Z 17.0N 53.2W 35 KT
24HR VT 30/0000Z 18.2N 54.9W 30 KT
36HR VT 30/1200Z 19.5N 56.3W 25 KT
48HR VT 01/0000Z 20.7N 57.6W 25 KT
72HR VT 02/0000Z 23.0N 60.0W 30 KT
96HR VT 03/0000Z 24.5N 62.5W 30 KT
120HR VT 04/0000Z 25.5N 64.5W 30 KT

$$
FORECASTER BLAKE

[RL3AO]

The NHC forecasts re-strengthening after 96 hours.

[cycloneye]

[americanrebel]

When are the newest models coming out?

[americanrebel]

http://www.nhc.noaa.gov/refresh/graphic ... e#contents

This graph makes it interesting. They are really not sure what will happend in 3 days. 30% gone, 30% TD, 30% TS, and 10% Hurricane.

[Chacor]

It is not a forecast per se, as it has to do with their historical accuracy.

About this product:

The table shows the probability that the maximum 1-minute wind speed of the tropical cyclone will be within any of eight intensity ranges during the next 72 hours. It is based on the outcomes of similar NHC wind speed forecasts during the period 1988-1997.

[Terry]

C'mon, Karen, you can do it. Hang in there.

[americanrebel]

I understand that, but still shows that the NHC has no idea what this system is going to do, not just in 5 days, but in 3 days. So who knows what it will do for the rest of her life.

[eaglegirl]

Just curious... why does Karen look like she has divided into 2 storms on the latest water vapor image? This is most noticable when viewing the loop.

Thanks!

[cpdaman]

WXMAN i picture you with a karen vodoo doll and repeatedly poking at it w/ various sharp objects. cursing it against any chance of a day off on the weekend. screaming affirmation's like you are opening into a tropical wave , you are opening to a tropical wave! LOL

although you do get about 7 months off starting NOV 1'st, right.

the shear is not abating, and like wxman says there does not appear to be a favorable enviornment for this thing at any time in the future, so just die already

[Matt-hurricanewatcher]

Winds just south of Karen are turning eastly. Only with in 50 miles of the southern quad is there westly winds. That tells me that she is weaking...On the other hand a 35 knot flag is still on quickscat. So its still a tropical storm.

[Meso]

[DanKellFla]

Now the HWRF is making it into a hurricane!!!! She is stubborn.
Bah!!! Women.

[wxman57]

WXMAN i picture you with a karen vodoo doll and repeatedly poking at it w/ various sharp objects. cursing it against any chance of a day off on the weekend. screaming affirmation's like you are opening into a tropical wave , you are opening to a tropical wave! LOL

although you do get about 7 months off starting NOV 1'st, right.

the shear is not abating, and like wxman says there does not appear to be a favorable enviornment for this thing at any time in the future, so just die already

7 months off? I have a full schedule of presentations starting December 4th at Moody Gardens in Galveston. Have to write papers for many of them. The presentations go through May or early June, including IADC, OTC, the January AMS meeting, the NHC in Orlando, DRJ in Orlando. We have numerous workshops & seminars which I have to prepare all the information for. There are many conferences at which we'll be exhibiting. Between writing all the papers and preparing the hour-long talks, I have to work with programmers/developers to get all the changes needed to our hurricane software done by March so we can do thorough testing. We're expanding to worldwide coverage in 2008, which means hiring 3-4 new hurricane team members and making sure they're trained. There's quite a bit more to do in the "off season" than the above. I can't take vacation between March and November, and I often work during any vacation days I take from December-January. As of today, September 29th, I've had 4 days off since August 27th (one weekend and 2 other mid-week comp days - and I worked all day on one of those "days off"). I don't mind having to work every day for storms like Dean or Felix that are real threats to our customers, but I have to work 10 hours today to cover pitiful things like Karen or TD 14 when I could have slept past 4am for a change.

So, that said, TAKE THAT KAREN!!! (sticking pins in my Karen doll).

I see the NHC is having a very hard time locating Karen's center. It's really hard to find the center of a tropical wave, which is all that's left of Karen. We'll see that shortly when the sun comes up. Now, where's my TD 14 voodoo doll...

[wxman57]

Winds just south of Karen are turning eastly. Only with in 50 miles of the southern quad is there westly winds. That tells me that she is weaking...On the other hand a 35 knot flag is still on quickscat. So its still a tropical storm.

No QuikSCAT for 12 hours, and 35 kts doesn't make a TS unless there is an LLC. Tropical waves can produce 35 kt winds too.



Ok, off to work. What else would I do every single "weekend"?

[Thunder44]

First visilbe images show a complety exposed LLC near 17N 54.5W. It appears to be moving west.

[HURAKAN]

LATEST:



Extremely exposed.

[wxman57]

First visilbe images show a complety exposed LLC near 17N 54.5W. It appears to be moving west.

That looks like a small eddy. Look near 15.8N/53.7W for a larger remnant swirl. Squalls are now 250 miles to the east and shear is still increasing (run a WV loop and look at the massive upper low it's moving into now. Goodbye Karen.

[Thunder44]

First visilbe images show a complety exposed LLC near 17N 54.5W. It appears to be moving west.

Upon further images, I see another LLC spinning to the SSE near 16N 53.5W. Perhaps these are really mesovortices spinning around a mean center diagonally between both them.