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 522 
 WTPZ42 KNHC 240835
 TCDEP2
 TROPICAL STORM NORA DISCUSSION NUMBER   6
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP172009
 200 AM PDT THU SEP 24 2009
  
 THE COVERAGE AND INTENSITY OF THE CENTRAL CONVECTION ASSOCIATED
 WITH NORA DECREASED IN THE HOURS PRIOR TO THE GOES-WEST ECLIPSE
 PERIOD. THIS LIKELY OCCURRED DUE TO INCREASING SOUTHWESTERLY WIND
 SHEAR ANALYZED BY UW-CIMSS AND THE SHIPS MODEL...ALONG WITH A
 DRYING TREND IN THE MID-TROPOSPHERE AND A DECREASE IN UPPER-LEVEL
 DIVERGENCE INDICATED BY SHIPS. SUBJECTIVE AND OBJECTIVE FINAL-T
 NUMBERS WERE A UNANIMOUS 3.0 AT 0600 UTC...AND ON THIS BASIS THE
 INITIAL INTENSITY IS LOWERED TO 45 KT.
  
 THE INTENSITY GUIDANCE IS IN UNANIMOUS AGREEMENT THAT NORA HAS
 PEAKED. THE SHIPS MODEL FORECASTS AT LEAST 15-20 KT OF SHEAR
 THROUGH THE PERIOD...WHICH IN COMBINATION WITH THE MARGINAL
 ATMOSPHERIC ENVIRONMENT SHOULD RESULT IN SLOW WEAKENING. THE
 INTENSITY FORECAST HAS BEEN ADJUSTED DOWNWARD IN CLOSE AGREEMENT
 WITH THE ICON INTENSITY CONSENSUS. NORA SHOULD BECOME A REMNANT LOW
 IN ABOUT 4 DAYS AND BE DISSIPATING BY DAY 5.
  
 BASED ON SEVERAL MICROWAVE FIXES AND GEOSTATIONARY IMAGERY PRIOR TO
 THE ECLIPSE...NORA APPEARS TO HAVE BEEN MOVING VERY LITTLE OVER THE
 PAST FEW HOURS. A 12-HOUR INITIAL MOTION ESTIMATE OF 300/04 WAS
 USED FOR THIS ADVISORY. THE TRACK MODEL GUIDANCE IS IN REASONABLY
 GOOD AGREEMENT ON THE OVERALL FORECAST SCENARIO. AS NORA WEAKENS...
 THE CYCLONE WILL TURN WESTWARD TO THE SOUTH OF THE LOW-LEVEL RIDGE
 THROUGH ABOUT 72 HOURS. BEYOND THAT TIME...MOST OF THE GUIDANCE
 SHOWS A TURN TOWARD THE WEST-NORTHWEST IN 3 OR 4 DAYS AS THE
 LOW-LEVEL RIDGE WEAKENS...ALLOWING WHAT IS LEFT OF NORA TO GAIN
 SOME LATITUDE. THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY NORTH
 THROUGH 24 HOURS TO ACCOUNT FOR THE INITIAL MOTION...AND THEN IS
 SIMILAR TO THE PREVIOUS PACKAGE THROUGH 72 HOURS. AT DAYS 4 AND 5
 THE FORECAST IS SHIFTED SLIGHTLY SOUTHWARD TOWARD THE TVCN
 MULTI-MODEL CONSENSUS AND LIES NEAR THE MIDDLE OF THE GUIDANCE
 ENVELOPE.
  
 THE INITIAL 34-KT WIND RADII WERE ADJUSTED BASED ON A QUIKSCAT PASS
 AT 0150 UTC.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      24/0900Z 17.2N 119.2W    45 KT
  12HR VT     24/1800Z 17.4N 120.0W    45 KT
  24HR VT     25/0600Z 17.5N 121.2W    40 KT
  36HR VT     25/1800Z 17.3N 122.5W    35 KT
  48HR VT     26/0600Z 17.3N 124.0W    30 KT
  72HR VT     27/0600Z 18.0N 127.0W    25 KT
  96HR VT     28/0600Z 19.0N 129.5W    25 KT...REMNANT LOW
 120HR VT     29/0600Z 19.6N 131.5W    20 KT...DISSIPATING
  
 $$
 FORECASTER BRENNAN
  
 
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