ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM IGNACIO DISCUSSION NUMBER 18 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT TUE AUG 26 2003 CONVECTION HAS WAXED AND WANED DURING THE PAST 12 HOURS AND ANOTHER BURST OF COLD TOPPED CONVECTION HAS DEVELOPED OVER THE LOW-LEVEL CENTER. HOWEVER...EACH SUCCESSIVE CONVECTIVE BURST HAS DECREASED IN AREAL COVERAGE...SO THE INITIAL INTENSITY HAS BEEN DECREASED TO 60 KT BASED ON A BLEND OF SATELLITE INITIAL INTENSITY ESTIMATES OF 65 KT FROM TAFB AND 55 KT FROM SAB. SATELLITE AND LIMITED SURFACE OBSERVATIONS SUGGEST THAT IGNACIO HAS MOVED VERY LITTLE DURING THE PAST 6 HOURS...WITH PERHAPS A SLOW NORTHWESTWARD DRIFT. STEERING CURRENTS REMAIN WEAK AND 26/00Z UPPER-AIR OBSERVATIONS ACROSS MEXICO AND THE SOUTHWESTERN UNITED STATES STILL SHOW NO CHANGE TO THE OVERALL SYNOPTIC-SCALE FLOW PATTERN DURING THE PAST 72 HOURS. A MID-LEVEL HIGH PRESSURE CELL CENTERED OVER THE U.S. DESERT SOUTHWEST SHOULD INHIBIT MUCH NORTHWARD MOTION AND KEEP IGNACIO MOVING SLOWLY NORTHWESTWARD OR WEST-NORTHWESTWARD OVER THE BAJA PENINSULA. THE FUTURE TRACK OF THE CYCLONE WILL DEPEND HEAVILY ON WHAT KIND OF VERTICAL CIRCULATION REMAINS AFTER THE SYSTEM TANGLES WITH THE BAJA CALIFORNIA MOUNTAINS. ONLY THE UKMET MODEL TAKES IGNACIO QUICKLY ACROSS THE PENINSULA AND INTO THE PACIFIC OCEAN. THE REST OF THE NHC MODEL GUIDANCE KEEPS A WEAK IGNACIO MOVING NORTHWESTWARD ALONG THE LENGTH OF THE PENINSULA. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK...EXCEPT SLIGHTLY SLOWER...AND IS VERY CLOSE TO THE GFDL MODEL WHICH HAS PERFORMED THE BEST THE PAST FEW MODEL RUNS. BOTH THE INTENSITY FORECAST AND TIME OF DISSIPATION HAVE BEEN DECREASED SINCE IGNACIO IS EXPECTED TO INTERACT WITH THE BAJA MOUNTAINS FOR A LONGER LENGTH OF TIME OWING TO THE SLOWER FORWARD SPEED. IT IS QUITE POSSIBLE THAT IGNACIO COULD COMPLETELY DISSIPATE AS A TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS. HOWEVER...THE CONTINUED SLOW MOTION MEANS THAT EXCESSIVE AMOUNTS OF RAINFALL WILL STILL POSE SERIOUS FLASH FLOODING AND MUD SLIDE THREATS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 26/0900Z 24.6N 110.7W 60 KT 12HR VT 26/1800Z 24.7N 111.0W 50 KT...INLAND 24HR VT 27/0600Z 25.1N 111.5W 40 KT...INLAND 36HR VT 27/1800Z 25.5N 111.8W 30 KT...DISSIPATING INLAND 48HR VT 28/0600Z 26.0N 112.2W 25 KT...DISSIPATING INLAND 72HR VT 29/0600Z 26.5N 113.0W 25 KT...REMNANT LOW 96HR VT 30/0600Z 27.0N 113.5W 20 KT...REMNANT LOW 120HR VT 31/0600Z 28.0N 114.5W 20 KT...REMNANT LOW NNNN
Alternate Formats
About Alternates -
E-Mail Advisories -
RSS Feeds
Cyclone Forecasts
Latest Advisory -
Past Advisories -
About Advisories
Marine Forecasts
Latest Products -
About Marine Products
Tools & Data
Satellite Imagery -
US Weather Radar -
Aircraft Recon -
Local Data Archive -
Forecast Verification -
Deadliest/Costliest/Most Intense
Learn About Hurricanes
Storm Names
Wind Scale -
Prepare -
Climatology -
NHC Glossary -
NHC Acronyms -
Frequently Asked Questions -
AOML Hurricane-Research Division
About Us
About NHC -
Mission/Vision -
Other NCEP Centers -
NHC Staff -
Visitor Information -
NHC Library
NOAA/
National Weather Service
National Centers for Environmental Prediction
National Hurricane Center
11691 SW 17th Street
Miami, Florida, 33165-2149 USA
nhcwebmaster@noaa.gov
Disclaimer
Privacy Policy
Credits
About Us
Glossary
Career Opportunities
Page last modified: Monday, 07-Feb-2005 16:49:57 UTC