Re: great blog Bobbi
Posted by Gianmarc on 8/23/2015, 5:16 pm
That phenomenon of the tropical phoenix rising from the ashes has always fascinated me.

Katrina and Andrew both were those types of storms--it is forgotten now because of the infamy for which Katrina now is known, but that storm, before it struck the Atlantic coast of Florida as a Cat 1, was written off several times in the mid-Atlantic, and had the appearance of an open wave at times.

To me, however, the difference is that Danny appears destined for a track into the heart of the mountainous terrain of Hispaniola AFTER already having gotten obliterated by shear, a beating that the current loops clearly show is underway in full force as I write this. Katrina never had to endure that twin pummeling. Jeanne ultimately survived that fate in 2004, but Jeanne was stronger when she struck Hispaniola than Danny will be. So, I think Danny soon will be a goner.

But, back to the phoenix storms, which, as I said, fascinate me: Katrina became TD #12 on Aug. 23, 2005, near the Bahamas, but the NHC discussion archive--and the memory of those of us who were posting here ten years ago (like me and Bobbi)--documents that actually it emerged out of TD #10, which had been written off to the extent that NHC decided to designate the regeneration as its own, stand-alone, new tropical entity, TD #12. See the highlighted portions of this NHC discussion from August 23, 2005. (The possibility that this "new" system that became Katrina just appeared out of nowhere on the doorstep of the Bahamas strains credulity, and the discussion explicitly acknowledges this):

TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT TUE AUG 23 2005

DATA FROM AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT...ALONG
WITH OBSERVATIONS FROM THE BAHAMAS AND NEARBY SHIPS...INDICATE THE
BROAD LOW PRESSURE AREA OVER THE SOUTHEASTERN BAHAMAS HAS BECOME
ORGANIZED ENOUGH TO BE CLASSIFIED AS TROPICAL DEPRESSION TWELVE.
THE INITIAL INTENSITY OF 30 KT IS BASED RECON WINDS OF 39 KT AT 800
FT...AND SHIP A8CI9 REPORTING 30-KT SUSTAINED WINDS AT 18Z IN THE
NORTHEAST QUADRANT. UPPER-LEVEL OUTFLOW IS WEAK...BUT IMPROVING AS
A SMALL ANTICYCLONE HAS BEEN DEVELOPING ABOVE THE LOW-LEVEL CENTER.

THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 310/07. THE LOW-LEVEL
CENTER HAS BEEN REFORMING WITHIN A LARGE CLEAR AREA NOTED IN
SATELLITE IMAGERY. HOWEVER...FLIGHT-LEVEL RECON WINDS CLEARLY
INDICATE A BROAD BUT OTHERWISE WELL-DEFINED LOW-LEVEL WIND FIELD.
THERE HAVE BEEN SEVERAL SMALL VORTICES DEVELOP WITHIN THE
CONVECTION IN THE EASTERN SEMICIRCLE AND THEN ROTATE WESTWARD OUT
FROM UNDER THE CONVECTION. THE INITIAL POSITION IS ROUGHLY THE
GEOMETRIC CENTER OF ALL THE SMALL SWIRLS...BUT SOME RE-ORGANIZATION
OF THE CENTER WITHIN THE CONVECTION IS POSSIBLE. TD-12 IS EXPECTED
TO CONTINUE MOVING SLOWLY NORTHWESTWARD TOWARD A WEAKNESS IN THE
MID-LEVEL SUBTROPICAL RIDGE. THIS WEAKNESS SHOWS UP BEST IN 500 MB
DATA...AND THEN DISAPPEARS BELOW AND ABOVE THAT LEVEL. BY 36-48
HOURS...ALL OF THE GLOBAL MODELS AND THE GFDL MODEL FORECAST THE
WEAKNESS TO FILL AND BE REPLACED BY A BROAD EAST-WEST ORIENTED
RIDGE. THIS SHOULD HELP TO DRIVE THE CYCLONE MORE WESTWARD ACROSS
SOUTHERN FLORIDA IN 60-72 HOURS...AND THEN INTO THE EASTERN GULF OF
MEXICO BY 96 HOURS. THIS SCENARIO IS CONSISTENT WITH THE NHC MODEL
CONSENSUS AND THE DEVELOPING SYNOPTIC PATTERN.

THE INTENSITY FORECAST IS A LITTLE TRICKY DUE TO THE UNCERTAINTY ON
EXACTLY WHEN A WELL-DEFINED CENTER WILL DEVELOP AND HOW SOON
CONVECTION WRAPS AROUND THE WEST SIDE OF THE CIRCULATION. THE
UPPER-LEVEL FLOW IS FORECAST TO REMAIN STRONGLY DIFLUENT FROM THE
NORTH FOR THE NEXT 24-36 HOURS...AND THEN BECOME NORTHEASTERLY TO
EASTERLY AFTER THAT. SINCE THE SHEAR IS ALSO FORECAST TO REMAIN
RELATIVELY LOW AT AROUND 10 KT AND SSTS WILL BE NEAR 31C UNDER THE
CENTER...AT LEAST STEADY INTENSIFICATION APPEARS TO BE IN ORDER. IF
CENTRAL CONVECTION DEVELOPS WITHIN THE NEXT 24 HOURS...THEN THIS
SYSTEM COULD REACH HURRICANE STRENGTH BEFORE IT MAKES LANDFALL. THE
OFFICIAL INTENSITY FORECAST IS SLIGHTLY LOWER THAN THE SHIPS MODEL.

THE NWS RULES GOVERNING THE NAMING OF TROPICAL CYCLONES SPECIFY
THAT...WITHIN A BASIN...WHEN A CYCLONE FORMS FROM THE REMNANT OF A
PREVIOUSLY EXISTING CYCLONE...THE OLD NAME/NUMBER IS RETAINED.
TROPICAL DEPRESSION TWELVE HAS A COMPLEX GENESIS THAT LIKELY
INCLUDES A MID-LEVEL REMNANT OF FORMER TROPICAL DEPRESSION TEN. A
REVIEW OF SATELLITE AND RAWINSONDE DATA OVER THE PAST WEEK OR SO
SUGGESTS THAT A SECOND DISTURBANCE APPROACHED AND COMBINED WITH THE
MID-LEVEL REMNANT OF TROPICAL DEPRESSION TEN ON 20 AUGUST. BECAUSE
IT IS IMPOSSIBLE TO DETERMINE WHICH OF THESE TWO SYSTEMS IS
ASSOCIATED WITH TODAY'S GENESIS...WE HAVE ELECTED TO USE THE
DESIGNATION TWELVE RATHER THAN TEN FOR THE NEW DEPRESSION. THIS
SITUATION DIFFERS FROM LAST YEAR'S REGENERATION OF IVAN...IN WHICH
THE LOW-LEVEL REMNANT OF THAT SYSTEM REMAINED A DISTINCT FEATURE
THAT COULD BE FOLLOWED CONTINUOUSLY UNTIL IT REGENERATED.

FORECASTER STEWART


FORECAST POSITIONS AND MAX WINDS

INITIAL      23/2100Z 23.2N  75.5W    30 KT
12HR VT     24/0600Z 24.0N  76.5W    35 KT
24HR VT     24/1800Z 25.0N  77.7W    40 KT
36HR VT     25/0600Z 25.7N  78.5W    45 KT
48HR VT     25/1800Z 26.0N  79.4W    60 KT
72HR VT     26/1800Z 26.3N  81.0W    50 KT...INLAND
96HR VT     27/1800Z 26.5N  83.5W    60 KT
120HR VT     28/1800Z 27.5N  86.0W    65 KT

92
In this thread:
Danny is still fighting to stay alive.... - Shalista, 8/22/2015, 9:25 am
< Return to the front page of the: message board | monthly archive this page is in
Post A Reply
This thread has been archived and can no longer receive replies.