Tropical Storm BETA

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TROPICAL STORM BETA DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT THU OCT 27 2005
 
MORNING SATELLITE IMAGERY SHOWS BETA AS A SMALL BUT WELL ORGANIZED
TROPICAL STORM.  VISIBLE IMAGERY SHOWS A CENTRAL DENSE OVERCAST
WITH SOME OUTER BANDING IN BOTH THE EAST AND WEST QUADRANTS...WITH
INFRARED IMAGERY INDICATING CLOUD TOPS TO -80C.  A RECENT SSM/I
OVERPASS SHOWS AN SMALL EYEWALL FORMING UNDER THE CDO.  SATELLITE
INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND SAB...AND THAT IS THE
INITIAL INTENSITY.

THE CENTER OF BETA IS SOMEWHAT TO THE EAST OF THE PREVIOUS
ADVISORY...AND THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 350/2. 
BETA IS DRIFTING TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE CAUSED
BY A LARGE DEEP-LAYER TROUGH OVER THE EASTERN UNITED STATES. 
LARGE-SCALE MODELS SUGGESTS THAT AFTER A SERIES OF SHORTWAVES PASS
THROUGH THE SOUTHERN END OF THE TROUGH IN THE NEXT 24-36 HR...THE
TROUGH SHOULD LIFT A LITTLE NORTHWARD AND ALLOW WEAK RIDGING TO
BUILD ACROSS THE NORTHWESTERN CARIBBEAN.  THIS EVOLUTION SHOULD
CAUSE BETA TO DRIFT SLOWLY NORTHWARD OR NORTH-NORTHWESTWARD FOR THE
NEXT 24-36 HR...FOLLOWED BY A WESTWARD MOTION.  ALL THE DYNAMICAL
MODELS EXCEPT THE CANADIAN...WHICH HAS HAD A NORTHWARD BIAS IN
SIMILAR SITUATIONS...FOLLOW THIS SCENARIO.  THE NEW FORECAST TRACK
IS SHIFTED TO THE NORTH AND EAST OF THE PREVIOUS TRACK BASED ON THE
INITIAL POSITION AND MOTION.  THE FORECAST TRACK NOW CALLS FOR
LANDFALL IN NORTHEASTERN NICARAGUA IN 72 TO 96 HR.

WITH THE SMALL EYEWALL AND GOOD OUTFLOW IN THE WESTERN SEMICIRCLE...
BETA APPEARS SET UP FOR RAPID INTENSIFICATION.  INDEED...THE RAPID
INTENSIFICATION INDEX ATTACHED TO THE SHIPS MODEL SHOWS A 56
PERCENT CHANCE OF 25 KT OR GREATER STRENGTHENING DURING THE NEXT 24
HOURS.  THE NEW INTENSITY FORECAST WILL NOT INCREASE QUITE THAT
MUCH...BUT DOES SHOW SIGNIFICANT STRENGTHENING DURING THE NEXT 72
HR SIMILAR TO THAT OF THE GFDL.  THE INTENSITY FORECAST MAY NEED TO
BE REVISED SIGNIFICANTLY UPWARD IN THE NEXT ADVISORY IF CURRENT
TRENDS CONTINUE.  ONE POSSIBLE RESTRAINING FACTOR IS THAT THE WARM
WATER OF THE SOUTHWESTERN CARIBBEAN IS RELATIVELY SHALLOW...AND THE
SLOW MOTION OF BETA WILL LIKELY RESULT IN SOME UPWELLING OF COLD
WATER.  HOWEVER...THE EFFECTS OF THIS MAY NOT BE FELT FOR 24 HR OR
MORE.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/1500Z 11.5N  81.3W    45 KT
 12HR VT     28/0000Z 11.9N  81.3W    55 KT
 24HR VT     28/1200Z 12.4N  81.4W    65 KT
 36HR VT     29/0000Z 12.9N  81.7W    75 KT
 48HR VT     29/1200Z 13.3N  82.1W    80 KT
 72HR VT     30/1200Z 13.5N  83.0W    85 KT
 96HR VT     31/1200Z 13.5N  84.5W    40 KT...INLAND
120HR VT     01/1200Z 13.0N  86.5W    25 KT...DISSIPATING
 
 
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