Tropical Storm IVO

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TROPICAL STORM IVO DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092013
200 PM PDT FRI AUG 23 2013
 
SATELLITE IMAGERY AND ASCAT DATA INDICATE THAT THE CENTER OF IVO
HAS REFORMED TO THE NORTHEAST DURING THE PAST SEVERAL HOURS.  THE
ASCAT DATA ALSO SHOW THAT THE MAXIMUM WINDS HAVE INCREASED TO
40 KT...AND THESE WINDS ARE MAINLY IN AN AREA ABOUT 150 N MI FROM
THE CENTER OVER THE EASTERN AND SOUTHERN SEMICIRCLES.

THE REFORMATION MAKES THE INITIAL MOTION VERY UNCERTAIN...WITH THE
BEST ESTIMATE OF 360/5.  IVO REMAINS ON THE WESTERN SIDE OF A
LOW/MID-LEVEL RIDGE OVER MEXICO...AND IT IS EXPECTED TO MOVE TOWARD
AN AREA OF SOUTHERLY STEERING FLOW BETWEEN A DEEP-LAYER RIDGE OVER
THE CENTRAL UNITED STATES AND A DEEP-LAYER TROUGH WEST OF
CALIFORNIA.  THIS COMBINATION SHOULD CAUSE THE CYCLONE TO MOVE
GENERALLY NORTH-NORTHWESTWARD FOR THE NEXT 48 HOURS.  AFTER THAT...
THERE IS STILL SIGNIFICANT DIVERGENCE IN THE GUIDANCE.  THE
GFS...HWRF...AND CANADIAN MODELS FORECAST IVO TO MOVE NORTHWARD
ACROSS NORTHERN BAJA CALIFORNIA INTO THE SOUTHWESTERN UNITED
STATES.  ON THE OTHER HAND...THE UKMET AND ECMWF MODELS FORECAST
THE SYSTEM TO SHEAR APART...WITH THE LOW-LEVEL CENTER STALLING OVER
THE PACIFIC WEST OF THE BAJA CALIFORNIA PENINSULA.  THE NAVGEM
SPLITS THE DIFFERENCE BETWEEN THESE EXTREMES...SHOWING A CONTINUED
SLOW NORTH-NORTHWESTWARD MOTION.  THE TRACK FORECAST STILL FOLLOWS
THE ECMWF/UKMET SCENARIO AND CALLS FOR THE LOW-LEVEL REMNANTS OF
IVO TO STALL WEST OF BAJA AFTER 48 HR.  THE NEW FORECAST TRACK IS
SHIFTED TO THE EAST OF THE PREVIOUS TRACK BASED ON THE POSITION OF
THE REFORMED CENTER.
 
GRADUAL STRENGTHENING APPEARS LIKELY UNTIL IVO REACHES COLDER SEA
SURFACE TEMPERATURES IN 24 HOURS OR SO.  AFTER THAT...THE CYCLONE
IS EXPECTED TO DEGENERATE TO A REMNANT LOW OVER THE COLD WATERS
WEST OF THE BAJA CALIFORNIA PENINSULA.  THE NEW INTENSITY FORECAST
SHOWS A SLIGHTLY HIGHER PEAK INTENSITY THAN THE PREVIOUS
FORECAST...BUT IS OTHERWISE SIMILAR TO IT.
 
THE NEW FORECAST TRACK AND THE LARGE SIZE OF THE WIND FIELD REQUIRE
A TROPICAL STORM WARNING AND WATCH FOR PORTIONS OF THE COAST OF THE
BAJA CALIFORNIA PENINSULA.  MOISTURE ASSOCIATED WITH IVO IS
EXPECTED TO SURGE NORTHWARD OVER THE BAJA CALIFORNIA PENINSULA...
NORTHWESTERN MEXICO AND THE SOUTHWESTERN UNITED STATES DURING THE
NEXT FEW DAYS...INCREASING THE POSSIBILITY OF HEAVY RAINS AND FLASH
FLOODING.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/2100Z 19.5N 111.8W   40 KT  45 MPH
 12H  24/0600Z 20.6N 112.0W   40 KT  45 MPH
 24H  24/1800Z 22.6N 112.6W   45 KT  50 MPH
 36H  25/0600Z 24.4N 113.4W   40 KT  45 MPH
 48H  25/1800Z 26.1N 114.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  26/1800Z 28.0N 115.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  27/1800Z 28.0N 116.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  28/1800Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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