Tropical Storm Karen has been shredded by high-level wind shear and is no longer an active cyclone. Here’s a satellite picture of Atlantic ocean storm systems on 9-30-07.

Storm update #5
Hurricane Karen is battling heavy wind shear and remains a tropical storm at this point, but that is expected to change in 48 hours or so. Here is the latest projected storm track which has shifted much further west and is now 290/9:

Hurricane Karen 9-28
Note the pronounced westward shift of the projected path.

Latest satellite view on 9-28:
Tropical Storm Karen 9-28 satellite view winds

Latest forecast on 9-28 from NHC:

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL STORM KAREN…LOCATED ABOUT 755 MILES EAST OF THE WINDWARD ISLANDS…THE CURRENT DIRECTION IS AN UNCERTAIN 290/9. KAREN IS EXPECTED TO MOVE ON A GENERAL WEST-NORTHWESTWARD TO NORTHWESTWARD TRACK FOR THE NEXT TWO TO THREE DAYS IN RESPONSE TO A LOW- TO MID-LEVEL RIDGE TO THE NORTH OF THE CYCLONE.

IN 48-72 HOURS…A MID-LATITUDE TROUGH IS EXPECTED TO APPROACH THE CYCLONE FROM THE WEST…AND IT IS DIFFICULT TO DETERMINE HOW MUCH OF A NORTHWARD STEERING INFLUENCE THE TROUGH WILL HAVE ON KAREN.

BY DAY 4…MOST OF THE GUIDANCE AGREES THAT A MORE WEST-NORTHWESTWARD TO WESTWARD MOTION COULD OCCUR AS THE TROUGH MOVES EAST AND HIGH PRESSURE BUILDS BACK IN TO THE NORTH OF THE CYCLONE.

THE STRONG WESTERLY SHEAR CURRENTLY AFFECTING THE CYCLONE IS EXPECTED TO PERSIST FOR THE NEXT 48 HOURS OR SO. THE SHEAR IS FORECAST TO RELAX AS RIDGING TO THE NORTH RETURNS. IF KAREN IS ABLE TO SURVIVE THE SHEAR FOR THE NEXT 48 HOURS…RESTRENGTHENING COULD OCCUR IN THE LATER FORECAST PERIODS.

Storm update 9-27:
Hurricane Karen is rapidly strengthening 950 miles west of the Windward Islands and the projected storm track has shifted much further west.

Current storm track is 300/13 and winds are currently 65 MPH. Here is the latest projected 5-day storm track from the national Hurricane Center on 9-27:
Hurricane Karen storm track 9-27
Compared to the previous storm track predictions, the projected track has shifted 300 miles west in the past 24 hours. Each square on the grid is roughly 300×300 miles.

Click here for a current satellite view of Karen’s winds and storm path in a time-lapse loop.

Hurricane Karen satellite view 9-27:
Hurricane Karen satellite view of winds 9-27

Here is the official NHC forecast for 9-27:

THE INITIAL MOTION IS SLIGHTLY FASTER…ABOUT 300/13. A WEAK RIDGE NORTH OF THE CYCLONE IS EXPECTED TO PERSIST FOR THE NEXT DAY OR SO WHICH SHOULD RESULT IN A GENERAL WEST-NORTHWESTWARD MOTION.AFTER 24- TO 36-HOURS…LARGE DIVERGENCE IN MODEL GUIDANCE EXISTS WHEN A DEEP MID- TO UPPER-LEVEL TROUGH APPROACHES FROM THE WEST. ONE GROUP OF MODELS MAINTAINS KAREN AS A STRONGER CYCLONE AND TAKES THE SYSTEM TOWARD THE NORTHWEST IN RESPONSE TO THE TROUGH.

THE SECOND GROUP FORECAST KAREN AS A MUCH WEAKER SYSTEM AND STEER IT WITH THE LOW-LEVEL FLOW. THE OFFICIAL TRACK FORECAST FOLLOWS THE LATTER SOLUTION…WHICH IS CLOSE WITH THE GFS AS WELL AS THE PREVIOUS ADVISORY PACKAGE.

Note that the projected storm track picture follows the weaker system projection and that several forecat models indicate Hurrican Karen could easily take a much more westward track than shown. That means this storm could easily be impacting the Virgin Islands and Puerto Rico within 5 days.

Storm update #2
Hurricane Karen is looming off the Windward Islands as Tropical Storm Karen is rapidly intensifying toward hurricane strength. Here is the latest Hurricane Karen forecast from the National Hurricane Center:

Projected storm track 9-26 5:00 AM:Hurricane Karen projected storm track 9-26

Satellite view of Hurricane Karen winds:
Hurricane Karen winds 9-26-07

Huricane Karen forecast to reach Category 2 strength in five days:

KAREN IS MOVING RIGHT ALONG THE PREVIOUS FORECAST TRACK WITH AN INITIAL MOTION OF 280/11. WITH THE RECENT DEVELOPMENT OF CONVECTION NEAR THE CENTER AND GENERALLY FAVORABLE ENVIRONMENTAL CONDITIONS…KAREN SHOULD STRENGTHEN DURING THE NEXT DAY OR TWO.THEREAFTER…THE INTENSITY FORECAST BECOMES HIGHLY PROBLEMATIC DUE TO THE POSSIBLE DEVELOPMENT OF UNFAVORABLE UPPER-LEVEL WINDS. THE GLOBAL MODELS SHOW STRONG WESTERLY FLOW IMPINGING UPON THE CYCLONE IN A DAY OR TWO.

HOWEVER…NEITHER THE GFDL NOR THE HWRF MODELS RESPOND TO THE SHEAR AND CONTINUE TO STRENGTHEN KAREN THROUGHOUT THE FORECAST. IN FACT…THE HWRF MODEL MAKES KAREN A CATEGORY 2 HURRICANE BY DAY 5.

SINCE SUCH ROBUST DEVELOPMENT SEEMS QUESTIONABLE GIVEN THE EXPECTED INCREASE IN VERTICAL SHEAR…THE OFFICIAL FORECAST IS BASED MORE ON THE SHIPS AND LGEM MODELS WHICH SHOW KAREN REACHING MINIMAL HURRICANE STRENGTH IN A DAY OR TWO FOLLOWED BY SLIGHT WEAKENING.

Storm update #1
Here is the projected Hurricane Karen storm path:Hurricane Karen 9-25 storm track

Here is the satellite view of Hurricane KarenĀ on 9-25-2007:
Hurricane Karen satellite view

Here is the latest National Hurricane Center forecast for Tropical Storm Karen to intensify to hurricane status:

INITIAL MOTION…290/13 THE SAME AS IN THE PREVIOUS ADVISORY. THE ENVIRONMENT AHEAD OF THE STORM IS QUESTIONABLE FOR STRENGTHENING. WITHIN THE NEXT FEW DAYS… GLOBAL MODELS DEPICT A COUPLE OF UPPER-LEVEL TROUGHS OVER THE CENTRAL SUBTROPICAL ATLANTIC THAT SHOULD CAUSE INCREASING SOUTHWESTERLY VERTICAL SHEAR OVER THE TROPICAL CYCLONE.IN SPITE OF THIS SEEMINGLY HOSTILE ENVIRONMENT…THE SHIPS MODEL PREDICTS KAREN TO BECOME A HURRICANE BY 48 HOURS AND TO MAINTAIN HURRICANE STRENGTH ALMOST TO THE END OF THE FORECAST PERIOD.THE LATEST RUN OF THE GFDL MODEL ALSO INTENSIFIES THE TROPICAL STORM INTO A HURRICANE AFTER 72 HOURS. IT IS DIFFICULT TO ACCEPT THIS GUIDANCE IN THE FACE OF SUCH STRONG PREDICTED SHEAR.

THEREFORE THE OFFICIAL FORECAST… AS IN THE PREVIOUS PACKAGE… STRENGTHENS KAREN TO JUST BELOW HURRICANE STATUS…

We’ll keep you posted on the latest developments for Tropical Storm Karen developing into Hurricane Karen.

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