Tropical Storm DANNY

ZCZC MIATCDAT5 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM DANNY DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU JUL 17 2003
 
DANNY CONTINUES TO BECOME BETTER ORGANIZED AS INDICATED BY IMPROVED
BANDING FEATURES AND A 17/0339Z TRMM OVERPASS INDICATING A 10 NMI
DIAMETER EYE-LIKE FEATURE. THE INITIAL INTENSITY IS INCREASED TO 45
KT BASED ON A 45-KT SATELLITE INTENSITY ESTIMATE FROM BOTH TAFB AND
SAB...AND THE AFOREMENTIONED EYE FEATURE. UPPER-LEVEL OUTFLOW IS
VERY CIRCULAR AND CONTINUES TO IMPROVE.
 
THE INITIAL MOTION IS 340/9. RECENT TRMM OVERPASSES AT 0339Z AND
0517Z CONFIRM THE SLOWER FORWARD SPEED ON THE PREVIOUS ADVISORY...
AND ALSO A POSITION TO THE SOUTHEAST OF THE CONVENTIONAL SATELLITE
FIX POSITIONS. THE FORECAST TRACK HINGES STRONGLY ON THE FUTURE
INTENSITY OF DANNY AND THE VERTICAL DEPTH OF THE CYCLONE. THE
GLOBAL AND REGIONAL MODELS ARE OF LITTLE USE EXCEPT FOR NOGAPS AND
ESPECIALLY THE CANADIAN MODEL. THE GFS...UKMET...GFDN...AND GFDL
MODELS WEAKEN DANNY FROM THE OUTSET AND LOSE AN IDENTIFIABLE
LOW-LEVEL CIRCULATION IN 36 TO 48 HOURS. MEANWHILE ...INFRARED AND
TRMM MCIROWAVE DATA SUGGEST THAT DANNY IS CLOSER TO BECOMING A
HURRICANE THAN IT IS TO DISSIPATING INTO A NON-ENTITY. SINCE THE
INTENSITY FORECAST CALLS FOR DANNY TO BECOME A HURRICANE IN 24 TO
36 HOURS...THE SYSTEM SHOULD REMAIN INTACT ALL THE WAY AROUND THE
DEEP-LAYERED SUBTROPICAL RIDGE THAT IS FORECAST TO REMAIN ALONG
ABOUT 35N LATITUDE THROUGHOUT THE 5 DAY PERIOD. THE CANADIAN MODEL
HANGS ONTO A LOW-LEVEL CIRCULATION THROUGH 120 HOURS...WHICH IS
SIMILAR TO THE NOGAPS...LBAR..AND ALL THREE BAM MODELS. THE
OFFICIAL FORECAST TRACK CALLS FOR DANNY TO MAKE A LARGE
ANTICYCLONIC LOOP AROUND THE SUBTROPICAL HIGH AND IS CLOSE TO THE
PREVIOUS FORECAST TRACK...EXCEPT FOR THE ADDITION OF A 120-HOUR
POSITION. THE MOST RECENT ANALOG FOR A HIGH-LATITUDE CLOCKWISE-
LOOPING TROPICAL CYCLONE WOULD BE HURRICANE ALBERTO IN 2000.
 
DANNY CURRENTLY HAS A CONVECTIVE CLOUD AND OUTFLOW PATTERN MORE
REMINISCENT OF A HURRICANE. THE CENTRAL CORE CONVECTION REMAINS
SMALL...BUT TIGHTLY WOUND AROUND THE WELL-DEFINED LOW-LEVEL CENTER
AS NOTED IN MICROWAVE SATELLITE DATA. SUBJECTIVE SST ANALYSES THIS
MORNING INDICATE THAT THE SHIPS INTENSITY MODEL HAS SSTS TOO COLD
ALONG THE PATH OF DANNY. IN FACT...SSTS WILL ACTUALLY INCREASE FROM
THE CURRENT 80F TO NEAR 82 F IN 24 HOURS AS DANNY PASSES OVER OR
NEAR A WARM EDDY ON THE SOUTH SIDE OF THE GULFSTREAM NEAR 40N AND
52W. THE WARM SSTS...COUPLED WITH THE IMPRESSIVE OUTFLOW PATTERN
AND FORECAST VERTICAL SHEAR OF 5 KT OR LESS...SHOULD ALLOW DANNY TO
REACH AND MAINTAIN AT LEAST MINIMAL HURRICANE STRENGTH UNTIL 36
HOURS...PERHAPS EVEN LONGER IF THE CYCLONE MAKES A TIGHTER LOOP
THAN CURRENTLY FORECAST KEEPING IT OVER WARM WATER LONGER.

FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0900Z 33.8N  55.8W    45 KT
 12HR VT     17/1800Z 35.0N  56.1W    55 KT
 24HR VT     18/0600Z 36.6N  55.9W    65 KT
 36HR VT     18/1800Z 38.4N  54.5W    65 KT
 48HR VT     19/0600Z 39.7N  52.5W    60 KT
 72HR VT     20/0600Z 41.3N  47.5W    55 KT
 96HR VT     21/0600Z 41.0N  43.0W    45 KT
120HR VT     22/0600Z 39.0N  39.0W    35 KT
 
 
NNNN