447 
 WTPZ42 KNHC 200852
 TCDEP2
  
 TROPICAL STORM BEATRIZ DISCUSSION NUMBER   4
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP022011
 200 AM PDT MON JUN 20 2011
  
 A SIGNIFICANT BURST OF VERY COLD TOPPED CONVECTION HAS DEVELOPED
 OVER THE LOW-LEVEL CIRCULATION CENTER AND THE CONVECTIVE PATTERN
 HAS TAKEN ON A CDO-LIKE APPEARANCE. HOWEVER...THE LOW-LEVEL CENTER
 OF BEATRIZ IS NOT LOCATED DIRECTLY IN THE CENTER OF THE CLOUD
 MASS...BUT INSTEAD IS LOCATED IN THE EASTERN PORTION OF THE CDO
 NEAR SOME VERY COLD OVERSHOOTING CLOUD TOPS OF -85 TO -88C. THIS
 MORE EASTWARD ADVISORY POSITION IS SUPPORTED BY EARLIER MICROWAVE
 SATELLITE DATA. THE INITIAL INTENSITY OF 50 KT IS BASED ON A BLEND
 OF SATELLITE ESTIMATES OF T3.5/55 KT FROM TAFB...T3.1/47 KT FROM
 UW-CIMSS ADT...AND AN INCREASED ORGANIZATION OF THE INNER CORE
 CONVECTION.
 
 THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 315/9. ALL OF THE MODELS
 MOVE A SHORTWAVE TROUGH ACROSS THE SOUTHERN U.S. PLAINS STATES AND
 NORTHERN MEXICO DURING THE NEXT 24-36 HOURS..WHICH BRIEFLY WEAKENS
 THE RIDGE TO THE NORTH OF BEATRIZ AND ALLOWS THE CYCLONE TO SLOW
 DOWN AND MOVE CLOSER TO THE COAST OF MEXICO. THERE IS...HOWEVER...
 A SLIGHT BIFURCATION IN THE MODEL GUIDANCE. THE NOGAPS AND UKMET
 MODELS KEEP THE CYCLONE MOVING NORTHWESTWARD JUST OFFSHORE OF THE
 COAST OF MEXICO...AND THEN TURN IT WESTWARD BY 72 HOURS AS THE
 MID-LEVEL RIDGE BUILDS BACK IN TO THE NORTH OF THE CYCLONE. THE
 ECMWF...GFS...GFDL...AND HWRF MODELS...HOWEVER...TAKE BEATRIZ JUST
 INLAND ALONG THE SOUTHWESTERN COAST OF MEXICO IN ABOUT 36 HOURS.
 ALTHOUGH THE LATTER MODELS MOVE THE CENTER JUST INLAND ALONG THE
 COAST AND RAPIDLY WEAKEN THE CYCLONE...ALL OF THE MODELS TAKE THE
 MID-LEVEL CIRCULATION WESTWARD AFTER 48 HOURS. THE OFFICIAL
 FORECAST IS SIMILAR TO THE PREVIOUS TRACK AND KEEPS BEATRIZ JUST
 OFFSHORE THROUGH 48 HOURS AND THEN TURNS THE CYCLONE WESTWARD AFTER
 THAT AS THE MID-LEVEL RIDGE IS EXPECTED TO BUILD BACK IN TO THE
 NORTH OF THE CYCLONE BY 48 HOURS. THIS IS BASED ON THE ASSUMPTION
 THAT BEATRIZ WILL MAINTAIN ITS VERTICAL CONTINUITY AND NOT DECOUPLE
 DUE TO LAND INTERACTION. HOWEVER...ONLY A SLIGHT DEVIATION TO THE
 RIGHT OF THE FORECAST TRACK IS NEEDED TO BRING THE CYCLONE NEAR OR
 INLAND ALONG THE SOUTHWESTERN COAST OF MEXICO. FOR THIS REASON...
 WATCHES AND WARNINGS HAVE BEEN EXTENDED NORTHWARD ALONG THE COAST.
 
 THE INNER CORE CONVECTION AND UPPER-LEVEL OUTFLOW PATTERNS HAVE
 IMPROVED CONSIDERABLY DURING THE PAST 6 HOURS. WITH AN ALREADY
 EXPANSIVE EQUATORWARD OUTFLOW PATTERN PRESENT...AND THE POLEWARD
 OUTFLOW EXPECTED TO IMPROVE BY 24 HOURS...THERE APPEARS TO BE NO
 PHYSICAL REASONS WHY BEATRIZ SHOULD NOT CONTINUE TO INTENSIFY FOR
 THE NEXT 48 HOURS OR SO...AND POSSIBLY EVEN RAPIDLY INTENSIFY
 DURING THAT TIME. THE OFFICIAL INTENSITY FORECAST IS HIGHER THAN
 THE AVAILABLE MODEL GUIDANCE AND INDICATES A SLIGHTLY FASTER THAN
 NORMAL RATE OF INTENSIFICATION FOR THE NEXT 24 HOURS SINCE THE
 VERTICAL SHEAR IS EXPECTED TO DECREASE TO NEAR 10 KT WHILE THE
 CYCLONE REMAINS OVER SSTS ABOVE 29C. BEYOND 48 HOURS...BEATRIZ IS
 EXPECTED TO ENCOUNTER SEA SURFACE TEMPERATURES OF 22-24C AND ALSO
 MOVE INTO A MORE STABLE AIR MASS...WHICH SHOULD RESULT IN THE
 CYCLONE WEAKENING INTO A REMNANT LOW BY DAY 5...IF NOT SOONER.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  20/0900Z 15.7N 102.6W   50 KT  60 MPH
  12H  20/1800Z 16.6N 103.2W   60 KT  70 MPH
  24H  21/0600Z 17.6N 104.0W   75 KT  85 MPH
  36H  21/1800Z 18.7N 104.7W   80 KT  90 MPH
  48H  22/0600Z 19.4N 105.8W   80 KT  90 MPH
  72H  23/0600Z 20.2N 109.1W   60 KT  70 MPH
  96H  24/0600Z 20.2N 112.5W   35 KT  40 MPH
 120H  25/0600Z 20.2N 116.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
  
 $$
 FORECASTER STEWART