Hurricane PATRICIA

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TROPICAL DEPRESSION PATRICIA DISCUSSION NUMBER  21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT SAT OCT 25 2003
 
PATRICIA REMAINS A POORLY ORGANIZED TROPICAL CYCLONE. NIGHTTIME
VISIBLE AND INFRARED SATELLITE IMAGERY INDICATE THAT DEEP
CONVECTION HAD COMPLETELY DISSIPATED NEAR THE ALLEGED LOW-LEVEL
CENTER OVERNIGHT...ALTHOUGH IT HAS MADE A SLIGHT COMEBACK DURING
THE PAST 1.5 HOURS. A 12Z SOUTHWEST WIND AT 14 KT AND 1010.0 MB
PRESSURE REPORTED BY SHIP ELVF6 LOCATED ABOUT 125 NMI SOUTHWEST OF
THE ALLEGED SATELLITE CENTER SUGGESTS THAT ANOTHER LOW-LEVEL CENTER
MAY BE DEVELOPING ABOUT 120 NMI FARTHER TO THE WEST. HOWEVER...A
MORE EASTWARD INITIAL POSITION IS BEING MAINTAINED FOR THIS
ADVISORY BASED ON CONTINUITY WITH THE PREVIOUS FORECAST TRACK AND
PAST POSITIONS...AND ALSO KEEPING THE CENTER TUCKED IN CLOSER TO
THE RECENT BURST OF STRONGER CONVECTION FARTHER EAST.
 
THE INITIAL MOTION ESTIMATE IS 340/5. DURING THE PAST 24 HOURS...
PATRICIA HAS BEEN TRYING TO MOVE NORTHWESTWARD AROUND THE WESTERN
PERIPHERY OF A MID-LEVEL RIDGE THAT EXTENDS WESTWARD FROM SOUTHERN
MEXICO. HOWEVER...MODERATE WESTERLY UPPER-LEVEL WINDS HAVE BEEN
FORCING/SHEARING THE CONVECTION EASTWARD...RESULTING IN A
NORTH-NORTHWESTWARD MOTION AND AN EAST-WEST ELONGATION IN THE
LOW-LEVEL WIND FIELD. THE NHC MODEL GUIDANCE REMAINS WIDELY
DIVERGENT AND THE TRACK PLOTS LOOK MORE LIKE A 'FOUNTAIN PATTERN'.
THE GFDN IS THE EASTERNMOST MODEL AND TAKES PATRICIA NORTHEASTWARD
...WHILE THE GFS IS THE WESTERNMOST MODEL AND TAKES THE CYCLONE
NORTHWESTWARD. THE OTHER MODELS ARE EVENLY SPREAD OUT SOMEWHERE IN
BETWEEN. SIMILAR TO THE PREVIOUS FORECAST...THE OFFICIAL FORECAST
TRACK FOR THIS ADVISORY WILL REMAIN SLOW AND A LITTLE TO THE LEFT
OF THE MIDDLE OF THE GUIDANCE ENVELOPE.

THE APPARENT EAST-WEST ELONGATION OF THE LOW-LEVEL CIRCULATION AND
THE WESTERLY SHEAR THAT HAS DISPLACED THE UPPER-LEVEL ANTICYCLONE
ABOUT 150 NMI EAST OF THE LOW-LEVEL CENTER SHOULD PREVENT ANY
SIGNIFICANT STRENGTHENING FROM OCCURRING. HOWEVER...THERE MAY BE A
FEW BRIEF INTERMITTENT BURSTS OF DEEP CONVECTION...ESPECIALLY AT
NIGHT...NEAR THE LOW-LEVEL CENTER TO KEEP PATRICIA BARELY ALIVE AS
A DEPRESSION FOR THE NEXT 36 HOURS OR SO. AFTERWARDS...DRY
MID-LEVEL AIR...STRONGER WESTERLY SHEAR...AND COOLER SEA-SURFACE
TEMPERATURES SHOULD WEAKEN THE CYCLONE AND GRADUALLY CAUSE IT TO
DISSIPATE...SIMILAR TO THE SHIPS AND GFDL INTENSITY MODELS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/1500Z 15.6N 113.9W    30 KT
 12HR VT     26/0000Z 16.4N 114.1W    30 KT
 24HR VT     26/1200Z 17.1N 114.4W    30 KT
 36HR VT     27/0000Z 17.6N 114.6W    30 KT
 48HR VT     27/1200Z 18.3N 114.8W    25 KT...DISSIPATING
 72HR VT     28/1200Z 19.0N 115.1W    20 KT...REMNANT LOW
 96HR VT     29/1200Z 20.0N 116.0W    20 KT...REMNANT LOW
120HR VT     30/1200Z...DISSIPATED
 
 
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