Lee-Delray
Weather Master
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The models are doing a lot of dancing with Karen. I think we need to see what happens over the next 3-4 days with shear.
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HanKFranK
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Loc: Graniteville, SC
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story next week ought to be whatever is in front of karen and karen itself. karen looks like it's going to hold out against the upper trough pretty well, and early next week it should be through it. assuming survival, nothing but a big ol' ridge in the western atlantic all next week. the ones that almost die and then come back can sometimes be the real bad ones. ingrid got ripped up by shear a while back, and it could happen just the same way again. hope so at least. a lot of the guidance is going to start coming further west with karen over the next couple of days.. should get a big hairier. how deep a system is south of bermuda in 3-4 days should determine whether it's hung and drifting in the upper trough axis or into the wheelhouse.
these latin-sounding storms in the gulf are playing games just lately. whereas humberto took days to organize but went ballistic just off the texas coast, lorenzo looks like it's going to make the run to hurricane strength before landfall as well. like it's predecessor it's a tiny storm and not likely to have a very wide swath of influence.
a lot of the globals are showing a coastal storm stuck under the ridge ahead of karen as the current upper trough swings through quickly and leaves a fairly large inverted trough in its wake. that might be a focal point or it could just as easily be a big messy nothing like the current one strung from florida to new england.
globals still trying to pop one more out near the cape verdes before last call. this late in september they usually stop rather abruptly.
HF 2152z27september
Edited by HanKFranK (Thu Sep 27 2007 05:57 PM)
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craigm
Storm Tracker
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Loc: Palm City, Florida
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I know it's a forum rule to not repost entire advisories or discussions but, I couldn't find a direct link to this discussion on the main page Unless you go through the link. I left out the Lorenzo part.
TCDAT2
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 SATELLITE INTENSITY ESTIMATES
FROM 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
--------------------
Why I'm here:
Weather hobbyist
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Rabbit
Weather Master
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Loc: Central Florida
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8pm--Lorenzo upgraded to hurricane with 75mph winds and 993mb pressure--fourth (possibly fifth) of the season
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Storm Hunter
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Loc: Panama City Beach, Fl.
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darn... gone all day... away from Panama City... and come back and Lorenzo makes a run up to Hurricane... just off shore of Old Mx.... Nice! Just looked over the recon data from today... wow.. so compact of system!!! Starting to look at the NOAA data on Karen... just glanced at a few models... looks like if karen survives another 2-3 days, things might get interesting.... as the ridge builds back to the north of it. Looks like its going to be, how much of shear can the system take for about 48-72 hrs?
11pm Adv. on karen..
HOWEVER...THIS TROUGH IS NOT EXPECTED
TO BE STRONG ENOUGH TO TURN THE STORM OUT TO SEA AND ALL MODELS
BUILD RIDGING TO THE NORTH OF THE STORM...FORCING A WEST-NORTHWEST
TURN AT THE END OF THE FORECAST PERIOD. THE OFFICIAL FORECAST IS
SHIFTED WESTWARD WITH THIS PACKAGE IN BEST AGREEMENT WITH THE
GFS/ECMWF MODELS AND IS ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE.
IF THE STORM WEAKENS MORE THAN EXPECTED...THIS FORECAST MAY HAVE TO
BE ADJUSTED FARTHER TO THE WEST..ESPECIALLY IN THE SHORT-TERM.
Also read Lorenzo Discus.... I am really interested to what recon finds in a bit when they get there.. actually how far down the drop of pressure went. Would like to know too if it will make cat 2 or more at landfall? this might set another 2007 record if it keeps agoing!
Edited by Storm Hunter (Thu Sep 27 2007 11:38 PM)
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cieldumort
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Loc: Austin, Tx
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It looks to me that it may be nearing time to toss out the model runs on Karen of the past several days. As of this morning, Karen has all but stalled, or has even been tracking a little bit to the southwest, if I buy the Extrap and my own eyes. Best I can tell, the LLC hasn't gone much of anywhere during the eclipse, and now, at the precipice of 50W, Karen is not yet even north of 14.5N, which was the approximate leftmost outlier for her position by this longitude, from the model suite average of the past several days.
This is the official word from at 5AM
0900 UTC FRI SEP 28 2007
TROPICAL STORM CENTER LOCATED NEAR 14.1N 49.8W AT 28/0900Z
POSITION ACCURATE WITHIN 30 NM
PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 9 KT
I just don't see it. I might be able to believe that is her motion of the last one hour, or so, but certainly not the average of the past five or six hours. In fact, this take is entirely substantiated by comparing the 11PM advisory position with today's 5AM.
11PM last night:
INITIAL 28/0300Z 14.8N 49.5W 50 KT
So, Karen went from 14.8 N 49.5W to 14.1N 49.8W Averaged out, that reads a lot more like SW, or even really SSW, over 6 hours. Karen is a highly-sheared tropical cyclone with intermittent bursts of deep convection within and about her center. However, this convection does not appear to have been consistent enough to allow her to follow the marching orders of all of these models.
Certainly this may be a relocation on the assumption that we didn't know where her center really was six hours ago, but looking at the night vision loops and microwave passes, that initial fix at 14.8N 49.5W looks to have been pretty darn good. I think Karen just went .. left.
With shear forecast to slacken some in the 2-4 day out time frame, and Karen likely to often remain rather shallow until then, and already having strayed considerably left of consensus, a consensus among models that now nearly unanimously send her westbound on Days 4 and/or 5, as it is.. I do think it is very close to, if not already, time to rethink these model forecasts.
This last comment from Mainelli from the 5AM Discussion really sums Karen up, methinks:
IT SHOULD BE NOTED THAT THERE ARE LARGE UNCERTAINTIES IN BOTH THE
TRACK AND INTENSITY AT THE LONGER FORECAST PERIODS.
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flanewscameraman
Weather Watcher
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Loc: Palm Beach County, FLA
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Does it appear that Karen will survive the shearing for the next few days? I am attaching a track of Andrew from 1992, just for your input
Edited by flanewscameraman (Fri Sep 28 2007 06:57 AM)
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Lee-Delray
Weather Master
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I find it somewhat amazing, that no one knows what, when and where Karen will do. From the look of the models it may even go under the late next week. Does anyone know what the wind shear around the Bahama's is going to be?
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weathernet
Storm Tracker
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Well, here we go again......, Karen moving north, wait west, wait....southwest? The shear is up, now down, but coming back?! What an appropriate storm for the year we are having! If Karen were a smaller system in an "average year", i'd say we would soon be witnessing the basic de-coupling of the low level from mid levels and "game over".
On first visible sat., it appeared to me that now Karen is drifting or moving northeast??!! Upon closer review, it would seem that has been tracking the center, which appears NOW to be a tighter vorticity which is obviously weakening against the shear; now acting as a more decoupled mid level, which is rotating around the broader low level surface low. In fact, perhaps not rotating around it so much, but perhaps soon to be entirely de-coupled from it. Again, in normal years, this would be the end of the system, but who knows.....
Models remain consistant with tending to re-develop and strengthen Karen, and in fact seem fairly in line with a late track cycle even more westward ( with odd exception to 0600Z run of and the European's 0Z run which from 7-10 days, just starts acting "wiggy" ).
I do not see how, given the overall appearance of Karen, how she maintains Tropical Storm designation. That said, I think we will see a large low level swirl moving around 180 degrees which will either do one of two things - eventually spin itself out and go away, or possibly redevelop under lighter shear in 2-3 days, only then to start tracking towards the Bahamas and possibly Florida. After many years of tracking and chasing hurricane's, i'd go with the "spin itself out option". This year however? Models seem more inconsistant than past years, and i'm at a point where practically nothing would surprise me.
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