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 546 
 WTNT42 KNHC 142036
 TCDAT2
 HURRICANE JULIA DISCUSSION NUMBER  10
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL122010
 500 PM AST TUE SEP 14 2010
  
 THE CLOUD PATTERN ASSOCIATED WITH JULIA HAS BECOME SOMEWHAT
 ASYMMETRIC DURING THE PAST SEVERAL HOURS...WITH A LARGE MASS OF
 DEEP CONVECTION HAVING FORMED SOUTHWEST OF THE CENTER. THE
 EYE THAT WAS VISIBLE EARLIER IS ALSO NO LONGER AS EVIDENT. THE
 OUTFLOW HAS BECOME A BIT RESTRICTED TO THE WEST...INDICATIVE OF
 SOME UPPER-LEVEL WESTERLY FLOW ALREADY IMPINGING UPON THE CYCLONE.
 DVORAK CI NUMBERS AT 1800 UTC ARE UNCHANGED FROM 1200 UTC...WHILE
 THE 3-HOURLY AVERAGED ADT VALUE IS AT 4.6. THE INITIAL INTENSITY IS
 HELD AT 75 KT FOR THIS ADVISORY IN AGREEMENT WITH SATELLITE
 ESTIMATES.
  
 RECENT FIXES INDICATE THAT JULIA HAS SLOWED A BIT FURTHER...AND THE
 INITIAL MOTION ESTIMATE IS 295/08.  WITH THE EXCEPTION OF THE
 UKMET...THE TRACK MODEL GUIDANCE IS IN BETTER AGREEMENT THIS CYCLE
 CONCERNING THE SHORT-TERM TRACK FORECAST.  JULIA IS EXPECTED TO
 MOVE ON A GENERAL NORTHWESTERLY COURSE DURING THE NEXT 24 HOURS AS
 IT INTERACTS WITH A MID- TO UPPER-LEVEL TROUGH EXTENDING
 SOUTHWESTWARD FROM A CYCLONE OVER THE NORTHEAST ATLANTIC.
 FROM 24-72 HOURS...GLOBAL MODELS INDICATE THAT JULIA SHOULD TURN
 WEST-NORTHWESTWARD WITH SOME INCREASE IN FORWARD SPEED UNDER THE
 INFLUENCE OF A BUILDING SUBTROPICAL RIDGE TO THE NORTH.  BEYOND THAT
 TIME...JULIA IS FORECAST TO TURN NORTH-NORTHWESTWARD AND THEN
 NORTHWARD ONCE IT REACHES THE WESTERN PERIPHERY OF THE SUBTROPICAL
 RIDGE. THE OFFICIAL NHC TRACK FORECAST IS NUDGED TO THE RIGHT AGAIN
 USING A MODEL CONSENSUS THAT EXCLUDES THE UKMET BUT HAS SHIFTED A
 BIT TO THE LEFT LATE IN THE PERIOD...FOLLOWING THE TREND IN THE
 GUIDANCE.
  
 WATER VAPOR IMAGERY SUGGESTS THAT WESTERLY SHEAR ASSOCIATED WITH A
 MID- TO UPPER-LEVEL TROUGH...PARTIALLY RELATED TO THE OUTFLOW OF
 HURRICANE IGOR...MAY ALREADY BE NEGATIVELY IMPACTING JULIA.  SHIPS
 MODEL OUTPUT INDICATES SOME INCREASE IN THIS SHEAR DURING THE NEXT
 COUPLE OF DAYS AT THE SAME TIME JULIA TRAVERSES MARGINAL SEA
 SURFACE TEMPERATURES.  ALTHOUGH THE CYCLONE IS FORECAST TO MOVE
 OVER WARMER WATERS AGAIN LATER IN THE FORECAST PERIOD...GLOBAL
 MODELS SHOW A STRONG SURGE OF NORTHERLY FLOW ASSOCIATED WITH THE
 OUTFLOW FROM HURRICANE IGOR ADVERSELY AFFECTING JULIA.  ALTHOUGH
 FEW CHANGES WERE MADE TO THE OFFICIAL NHC INTENSITY FORECAST...
 JULIA COULD BE WEAKER THAN FORECAST IF THE PREDICTED SHEAR
 MATERIALIZES.
   
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      14/2100Z 16.7N  30.2W    75 KT
  12HR VT     15/0600Z 17.8N  31.4W    80 KT
  24HR VT     15/1800Z 19.5N  33.1W    80 KT
  36HR VT     16/0600Z 21.3N  35.7W    75 KT
  48HR VT     16/1800Z 22.8N  39.1W    70 KT
  72HR VT     17/1800Z 25.0N  46.0W    70 KT
  96HR VT     18/1800Z 29.1N  50.5W    60 KT
 120HR VT     19/1800Z 33.0N  51.0W    50 KT
  
 $$
 FORECASTER KIMBERLAIN
  
 
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