Tropical Storm BETA

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TROPICAL STORM BETA DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT FRI OCT 28 2005
 
AN AIR FORCE RESERVE HURRICANE HUNTER HAS JUST MEASURED A CENTRAL
PRESSURE OF 990 MB AND REPORTED A PARTIAL 15 N MI WIDE EYE. 
HOWEVER...THE MAXIMUM 850 MB FLIGHT-LEVEL WINDS ARE 51 KT...WHICH
GENERALLY DOES NOT SUPPORT THE 55 KT INTENSITY SUGGESTED BY THE
CENTRAL PRESSURE AND THE SATELLITE INTENSITY ESTIMATES.  IT MAY BE
THAT A TIGHTER INNER CORE EXISTED EARLIER AND WAS DISRUPTED BY THE
NORTHEASTERLY SHEAR...AND IS JUST NOW COMING BACK TOGETHER.  THE
INITIAL INTENSITY WILL REMAIN 55 KT FOR THIS ADVISORY.

THE INITIAL MOTION REMAINS 360/4.  WHILE THE CENTER FIXES DO NOT YET
SHOW A SIGNIFICANT WESTWARD COMPONENT TO THE MOTION...A NET
NORTHWESTWARD SHIFT OF THE CLOUD MASS MAY BE A PRECURSOR OF THE
EXPECTED NORTHWESTWARD TURN.  WATER VAPOR IMAGERY INDICATES THAT A
STRONG SHORTWAVE TROUGH IS MOVING EASTWARD ACROSS THE SOUTHEASTERN
U. S. AND THE EASTERN GULF OF MEXICO.  THE DYNAMICAL MODELS
CONTINUE TO FORECAST HEIGHTS TO RISE IN THESE AREAS AFTER THE
TROUGH MOVES INTO THE ATLANTIC IN 12-18 HR.  SATELLITE IMAGERY AND
SURFACE OBSERVATIONS ALSO SUGGEST THAT THE LOW-LEVEL RIDGE OVER THE
WESTERN ATLANTIC AND NORTHERN CARIBBEAN IS SLOWLY BUILDING WESTWARD. 
THIS EVOLUTION SHOULD TURN BETA MORE NORTHWESTWARD DURING THE NEXT
12-24 HR AND MORE WESTWARD THEREAFTER.  THE GFS...GFDL...AND NOGAPS
MODELS STILL CALL FOR A WESTWARD TURN...ALTHOUGH ALL THREE ARE
SOMEWHAT TO THE NORTH OF THEIR PREVIOUS RUNS.  THE UKMET STILL
CALLS FOR A MORE GRADUAL TURN...BUT STILL BRINGS BETA INLAND IN
NICARAGUA.  THE NEW FORECAST TRACK IS SHIFTED SLIGHTLY TO THE NORTH
FOR THE FIRST 48 HR...CALLING FOR LANDFALL IN NORTHEASTERN
NICARAGUA IN 36-48 HR.  THE NEW TRACK REMAINS SOUTH OF THE UKMET
AND JUST NORTH OF THE OVERALL MODEL CONSENSUS.
 
ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE 15 KT OF
EASTERLY VERTICAL SHEAR OVER BETA.  THE SHIPS MODEL SUGGESTS THIS
WILL PERSIST FOR 12 HR OR SO...AND THE INTENSITY FORECAST HAS BEEN
REDUCED SLIGHTLY DURING THAT TIME.  AFTER THE SHEAR DECREASES...
CONDITIONS CONTINUE TO APPEAR FAVORABLE FOR RAPID STRENGTHENING...
AND THE GFDL BRINGS A STRONG CATEGORY TWO HURRICANE INTO NICARAGUA. 
THUS...THE INTENSITY FORECAST CONTINUES TO CALL FOR BETA TO REACH
85 KT BEFORE LANDFALL.  THE CYCLONE SHOULD WEAKEN AFTER LANDFALL...
ESPECIALLY OVER THE CENTRAL AMERICAN MOUNTAINS...AND IT MAY BE THAT
HANGING ON TO IT FOR 120 HR MAY BE GENEROUS.

THE WIND RADII HAVE BEEN REDUCED DOWNWARD BASED ON SURFACE AND
AIRCRAFT DATA.  BETA HAS BEEN MUCH SLOWER TO GROW IN SIZE THAN
ANTICIPATED...AND IT MAY BE THAT EVEN THE NEW FORECAST RADII ARE
TOO LARGE.  WHILE THE WINDS MAY SPREAD ONSHORE LATER THAN
ORIGINALLY FORECAST...THE HEAVY RAINS WILL BE SPREADING INTO
CENTRAL AMERICA STARTING TONIGHT.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/2100Z 13.3N  81.1W    55 KT
 12HR VT     29/0600Z 13.8N  81.3W    60 KT
 24HR VT     29/1800Z 14.3N  82.0W    70 KT
 36HR VT     30/0600Z 14.6N  82.9W    85 KT
 48HR VT     30/1800Z 14.8N  83.9W    65 KT...INLAND
 72HR VT     31/1800Z 15.0N  86.0W    30 KT...INLAND
 96HR VT     01/1800Z 15.0N  88.0W    25 KT...INLAND DISSIPATING
120HR VT     02/1800Z 16.0N  89.5W    20 KT...INLAND REMNANT LOW
 
 
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