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 384 
 WTPA44 PHFO 182054
 TCDCP4
 
 TROPICAL STORM GUILLERMO DISCUSSION NUMBER  27
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP102009
 1100 AM HST TUE AUG 18 2009
 
 TROPICAL STORM GUILLERMO HAS MANAGED TO MAINTAIN ITS INTENSITY THIS
 MORNING DESPITE ITS RAGGED APPEARANCE ON SATELLITE AND BEING IN
 AN ENVIRONMENT OF STRONG VERTICAL WIND SHEAR. THE SOUTHWESTERLY
 WIND SHEAR...IN EXCESS OF 40 KT ACCORDING TO THE RECENT UW-CIMSS
 ANALYSIS...IS BEING CREATED BY AN UPPER LOW CENTERED ABOUT 650
 MILES TO THE SOUTHWEST OF GUILLERMO. THIS UPPER LOW IS ALSO
 CREATING OUTFLOW ALOFT THAT HAS HELPED TO MAINTAIN DEEP CONVECTION
 WITHIN THE NORTH QUADRANT OF GUILLERMO. THIS...TOGETHER WITH A
 TIGHT PRESSURE GRADIENT BETWEEN THE SYSTEM AND A 1030 MB SURFACE
 HIGH TO THE NORTH...HAS ALLOWED GUILLERMO TO MAINTAIN ITS
 INTENSITY.
 
 A MORNING QUIKSCAT PASS INDICATES AN ASYMMETRIC WIND FIELD...WITH A
 BROAD AREA OF TROPICAL STORM FORCE WINDS WITHIN THE NORTHERN
 QUADRANT AND MUCH WEAKER WINDS TO THE SOUTH. AN AMBIGUITY ANALYSIS
 ON THESE DATA CONFIRMED THE PRESENCE OF A CLOSED CIRCULATION...
 DESPITE THE RAGGED AND ELONGATED APPEARANCE OF THE LOW LEVEL CENTER
 ON VISIBLE SATELLITE. CURRENT INTENSITY VALUES FROM ALL THE FIX
 AGENCIES CAME IN AT 2.0...SUGGESTING A WEAKER SYSTEM...BUT THE
 UW-CIMSS SATCON ESTIMATE ESTIMATED 39 KT...MAINLY DUE TO AMSU
 DETECTING A PERSISTENT WARM CORE ALOFT. THUS...THE INITIAL
 INTENSITY IS HELD AT 40 KT.
 
 THE FORECAST CONTINUES TO MOVE GUILLERMO TO THE NORTHWEST OVER THE
 NEXT 36 TO 48 HOURS INTO A WEAKNESS IN THE LOW TO MID LEVEL RIDGE
 TO THE NORTH CREATED BY THE ABOVE MENTIONED UPPER LOW. DURING THIS
 TIME...SOUTHERLY VERTICAL WIND SHEAR SHOULD TAKE ITS TOLL ON
 GUILLERMO...WEAKENING THE SYSTEM TO A DEPRESSION BY 24 HOURS AND
 NOT ALLOWING IT TO TAKE ADVANTAGE OF WARMING SST ALONG THE TRACK.
 AROUND 48 HOURS THE SHEAR WILL SHIFT FROM THE NORTHEAST AND REMOVE
 THE DIFLUENT FLOW ALOFT CURRENTLY SUPPORTING CONVECTION. THE
 DISSIPATING SYSTEM IS THEN FORECAST TO TURN ON A WESTERLY THEN WEST
 SOUTHWEST TRACK AS IT WEAKENS INTO A REMNANT LOW BY 96 HOURS AND 
 BECOMES STEERED BY THE LOW LEVEL FLOW. THE TRACK SCENARIO FALLS 
 ROUGHLY IN THE MIDDLE OF THE DYNAMICAL GUIDANCE ENVELOPE AND CLOSE 
 TO THE HWRF...WHILE THE INTENSITY FORECAST WEAKENS THE SYSTEM 
 SLIGHTLY FASTER THAN GUIDANCE.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      18/2100Z 27.0N 151.2W    40 KT
  12HR VT     19/0600Z 28.6N 153.7W    35 KT
  24HR VT     19/1800Z 30.0N 157.1W    30 KT
  36HR VT     20/0600Z 30.9N 160.5W    30 KT
  48HR VT     20/1800Z 31.4N 163.4W    25 KT
  72HR VT     21/1800Z 31.2N 169.1W    25 KT...DISSIPATING
  96HR VT     22/1800Z 30.4N 174.6W    20 KT...REMNANT LOW
 120HR VT     23/1800Z 28.8N 179.9E    20 KT...REMNANT LOW
  
 $$
 FORECASTER WROE
  
 
 
 
 
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