ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM MARTY DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 AM PDT FRI SEP 19 2003 EARLIER QUIKSCAT AND SSMI MICROWAVE SATELLITE DATA...ALONG WITH THE FIRST COUPLE OF VISIBLE IMAGES...SUGGEST THAT THE CENTER OF MARTY IS A LITTLE FARTHER EAST OF THE PREVIOUS ADVISORY POSITION. THIS PLACES THE LOW-LEVEL CENTER NEAR THE EASTERN EDGE OF THE NOW WEAKENING CENTRAL DEEP CONVECTION. THE INITIAL INTENSITY OF 40 KT IS BASED ON A COMBINATION OF A SATELLITE INTENSITY ESTIMATE OF T2.5...OR 35 KT...FROM TAFB AND SAB...AND A DATA T-NUMBER OF T3.0 ...OR 45 KT...FROM TAFB. THE INITIAL MOTION ESTIMATE IS 300/6. THERE IS A LITTLE LESS UNCERTAINTY IN THE LOCATION OF THE CENTER NOW...SO THE PAST HISTORICAL TRACK HAS BEEN ADJUSTED TO THE EAST AND SLOWER. THIS HAS HAD A SIGNIFICANT IMPACT ON THE NHC MODEL GUIDANCE FORECAST TRACKS FOR THIS ADVISORY PACKAGE. THE GFDL...GFS ENSEMBLE...AND UKMET MODELS ARE NOW INDICATING RECURVATURE TO THE NORTH AND NORTHEAST THROUGH A WEAKENING SUBTROPICAL RIDGE LOCATED ACROSS NORTHWESTERN MEXICO AND EXTENDING WESTWARD ACROSS BAJA CALIFORNIA. THE GFS MODEL DOES NOT WEAKEN THE RIDGE AS MUCH AS THE OTHER THREE MODELS DO... WHILE THE NOGAPS MODEL FORECASTS MARTY TO BE A VERY WEAK SYSTEM THAT IS DRIVEN RAPIDLY WESTWARD BY THE MODERATE LOW-LEVEL EASTERLIES. IT APPEARS THAT NOGAPS IS KEEPING MARTY TOO WEAK...SO THE WESTWARD TRACK HAS BEEN DISCOUNTED AT THIS TIME. LESS WEIGHT HAS ALSO BEEN PLACED ON THE RECURVATURE FORECAST OF THE OTHER MODELS...EXCLUDING THE GFS. THE CURRENT STRENGTH OF THE SUBTROPICAL RIDGE AND THE RATHER WEAK LOOKING SHORTWAVE TROUGH FORECAST TO DIG SOUTHEASTWARD FROM THE CENTRAL PACIFIC MAY NOT BE STRONG ENOUGH TO COMPLETELY CAPTURE MARTY. HOWEVER...THE OFFICIAL FORECAST TRACK WAS SHIFTED WELL TO THE RIGHT...ESPECIALLY AFTER 72 HOURS...DUE TO THE REPOSITIONING OF THE CYCLONE CENTER AND ALSO TO BRING THE FORECAST TRACK CLOSER TO THE GFS SOLUTION AND THE NHC MODEL CONSENSUS. RECURVATURE ACROSS BAJA CALIFORNIA AFTER 72 HOURS IS A LOW-PROBABILITY ALTERNATE SCENARIO AT THIS TIME...BUT IT WILL GIVEN MORE CONSIDERATION IN THE NEXT ADVISORY IF MORE OF THE 12Z MODELS BEGIN TO SUGGEST A NORTH AND NORTHEASTWARD MOTION BY 72 HOURS. MARTY IS FORECAST TO REMAIN OVER 29-30C SSTS AND IN A LOW-SHEAR... LESS THAN 5 KT...UPPER-LEVEL ENVIRONMENT...WHICH WOULD TEND TO FAVOR A RAPID INTENSIFICATION TREND. HOWEVER...DUE TO THE UNCERTAINTY IN THE EXACT LOCATION OF THE LOW-LEVEL CENTER WITHIN THE CENTRAL DEEP CONVECTION...AND THE FACT THAT SOME MID-LEVEL EASTERLIES AND DRY AIR IS UNDERCUTTING THE IMPRESSIVE OUTFLOW PATTERN...ONLY MODEST INTENSIFICATION IS FORECAST. THE INTENSITY FORECAST IS SIMILAR TO BUT SLIGHTLY FASTER THAN THE GFDL AND SHIPS INTENSITY MODEL FORECASTS. HOWEVER...IF THE CENTER BECOMES EMBEDDED IN THE DEEP CONVECTION LATER TODAY AND THE CONVECTION INCREASES SIGNIFICANTLY ...THEN MARTY COULD INTENSIFY MORE QUICKLY THAN THE CURRENT FORECAST IS INDICATING. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 19/1500Z 17.4N 107.5W 40 KT 12HR VT 20/0000Z 17.9N 108.3W 45 KT 24HR VT 20/1200Z 18.4N 109.7W 55 KT 36HR VT 21/0000Z 19.0N 111.3W 65 KT 48HR VT 21/1200Z 19.5N 112.8W 75 KT 72HR VT 22/1200Z 20.5N 115.5W 80 KT 96HR VT 23/1200Z 21.5N 118.0W 75 KT 120HR VT 24/1200Z 23.5N 121.0W 65 KT 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 16:49:59 UTC