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 348 
 WTNT44 KNHC 090310
 TCDAT4
  
 TROPICAL STORM MARIA DISCUSSION NUMBER  10
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
 1100 PM AST THU SEP 08 2011
 
 THE CLOUD PATTERN OF MARIA HAS STABILIZED THIS EVENING...ALBEIT IN A
 RATHER DISORGANIZED CONDITION.  PATCHES OF CONVECTION ARE OCCURRING
 OVER THE NORTHERN SEMICIRCLE OF A BROAD AREA OF CYCLONIC
 ROTATION...WITH AN OVERALL INCREASE IN CONVECTIVE COVERAGE DURING
 THE PAST SEVERAL HOURS.  DUE TO COMMUNICATIONS PROBLEMS...THE
 AIRCRAFT THAT INVESTIGATED MARIA WAS UNABLE TO TRANSMIT A FULL DATA
 SET.  THEREFORE...IT WAS NOT DETERMINED WITH CERTAINTY WHETHER A
 WELL-DEFINED CLOSED CIRCULATION STILL EXISTED.  HOWEVER...THE PLANE
 MEASURED A CENTRAL PRESSURE OF 1005 MB...SHOWING THAT AT THE VERY
 LEAST A LOW PRESSURE CENTER STILL EXISTED.  BASED ON THIS...MARIA
 IS MAINTAINED AS A TROPICAL CYCLONE.  THE INITIAL INTENSITY OF
 35 KT IS BASED ON THE AIRCRAFT DATA AND RECENT BUOY REPORTS.
 
 THE INITIAL MOTION IS 275/18.  THE DYNAMICAL MODELS FORECAST THE
 CYCLONE TO TURN WEST-NORTHWESTWARD DURING THE NEXT 12-24 HOURS
 TOWARD A WEAKNESS IN LOW/MID-LEVEL SUBTROPICAL RIDGE TO THE
 NORTH...A WEAKNESS POSSIBLY CAUSED BY AN UPPER-LEVEL LOW SEEN IN
 WATER VAPOR IMAGERY NEAR 23N61W.  WHILE THE NEW FORECAST TRACK
 FOLLOWS THIS SCENARIO...THE CURRENT RAPID MOTION SUGGESTS THIS TURN
 WILL BE MORE GRADUAL THAN THE MODEL GUIDANCE IS FORECASTING...AND
 THUS THE FIRST PART OF THE NEW TRACK IS ON THE SOUTH SIDE OF THE
 GUIDANCE ENVELOPE.  AFTER 24 HOURS...ALL OF THE GUIDANCE FORECASTS
 MARIA TO MOVE WEST-NORTHWESTWARD TO NORTHWESTWARD TOWARD THE
 WESTERN END OF THE SUBTROPICAL RIDGE AS A DEEP-LAYER TROUGH MOVES
 THROUGH THE SOUTHEASTERN UNITED STATES.  AFTER SHIFTING TO THE LEFT
 FOR THE PREVIOUS ADVISORY...THE GUIDANCE FOR THE POST-24 HOUR
 PERIOD HAS SHIFTED TO THE RIGHT FOR THIS ADVISORY.  THE END OF THE
 FORECAST TRACK WILL SHOW A SMALL RIGHT TURN...BUT STILL LIES TO THE
 LEFT OF THE CENTER OF THE GUIDANCE ENVELOPE.  IT SHOULD BE NOTED
 THAT THE UKMET AND ECMWF MODELS ARE STILL TO THE WEST OF THE NEW
 FORECAST AT 120 HOURS.
 
 THE INTENSITY GUIDANCE HAS BECOME A BIT MORE BULLISH THIS
 EVENING...WITH THE SHIPS AND LGEM MODELS NO LONGER FORECASTING
 MARIA TO WEAKEN TO A DEPRESSION.  INDEED...THE SHIPS MODEL SHOWS
 THE VERTICAL WIND SHEAR DECREASING TO LESS THAN 10 KT DURING THE
 NEXT 24 HOURS AND REMAINING THAT LIGHT THROUGH 96 HOURS.  GIVEN THE
 PRESENCE OF THE UPPER-LEVEL LOW TO THE NORTHWEST AND THE FORECAST
 UPPER-LEVEL WIND PATTERNS OF THE VARIOUS MODELS...THAT MIGHT BE A
 BIT OPTIMISTIC.  THE NEW INTENSITY FORECAST NOW CALLS FOR MARIA TO
 MAINTAIN A 35-KT INTENSITY FOR THE NEXT 24 HOURS...FOLLOWED BY
 GRADUAL STRENGTHENING THROUGH THE REST OF THE FORECAST PERIOD.  THE
 NEW INTENSITY FORECAST IS NEAR THE LOWER EDGE OF THE INTENSITY
 FORECAST GUIDANCE.
 
 THE CHANGE IN THE INTENSITY FORECAST FOR THE FIRST 24 HOURS REQUIRES
 TROPICAL STORM WARNINGS FOR PORTIONS OF THE LEEWARD ISLANDS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  09/0300Z 13.3N  54.6W   35 KT  40 MPH
  12H  09/1200Z 13.5N  57.2W   35 KT  40 MPH
  24H  10/0000Z 14.7N  60.4W   35 KT  40 MPH
  36H  10/1200Z 16.3N  62.8W   40 KT  45 MPH
  48H  11/0000Z 17.8N  65.2W   45 KT  50 MPH
  72H  12/0000Z 21.0N  69.5W   50 KT  60 MPH
  96H  13/0000Z 23.5N  73.0W   55 KT  65 MPH
 120H  14/0000Z 26.0N  75.0W   60 KT  70 MPH
  
 $$
 FORECASTER BEVEN
  
 
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