ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ANDRES DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT WED MAY 21 2003 SEVERAL SSM/I AND AMSU OVERPASSES DURING THE NIGHT INDICATE THAT ANDRES CONTINUES TO BE SHEARED...WITH THE LOW-LEVEL CENTER AT LEAST PARTLY EXPOSED TO THE WEST OF THE MAIN CONVECTION. AT THE MOMENT...A RATHER IMPRESSIVE BURST WITH CLOUD TOPS COLDER THAN -80C IS OCCURRING. SATELLITE INTENSITY ESTIMATES ARE 45 KT FROM SAB AND 35 KT FROM TAFB AND AFWA. THE INITIAL INTENSITY REMAINS 35 KT FOR THIS PACKAGE...ALTHOUGH GIVEN THE PROXIMITY OF THE CENTER TO THE CONVECTIVE BURST THERE IS A CHANCE THE STORM IS A LITTLE STRONGER. FIXES FROM THE MICROWAVE DATA INDICATE THE INITIAL MOTION IS 270/13. ANDRES IS SOUTH OF A LARGE MID/UPPER-LEVEL ANTICYCLONE SEEN IN WATER VAPOR IMAGERY...WHICH HAS SHIFTED A LITTLE WESTWARD SINCE LAST NIGHT. THIS HAS LIKELY HELPED MAINTAIN ANDRES ON A WESTERLY COURSE TO THE SOUTH OF MOST OF THE MODEL GUIDANCE FOR THE PAST 24 HR. LARGE-SCALE MODELS CONTINUE TO FORECAST THE RIDGE TO SHIFT WESTWARD AND GRADUALLY WEAKEN...AND THAT ANDRES WILL TURN MORE WEST-NORTHWESTWARD. NHC TRACK GUIDANCE ALSO AGREES WITH THIS. SINCE THE MODELS HAVE BEEN TOO QUICK IN MAKING THIS TURN...THE OFFICIAL FORECAST WILL CALL FOR A WESTWARD MOTION FOR 12-24 HR MORE...FOLLOWED BY A GRADUAL TURN TOWARD THE WEST-NORTHWEST. THIS TRACK IS ON THE SOUTH SIDE OF THE ENVELOPE OF GUIDANCE...AND FOR THE FIRST 36 HR...ON THE SOUTH EDGE OF IT. THE INTENSITY FORECAST IS PROBLEMATIC. MODEL FORECASTS FROM LAST NIGHT DID NOT INDICATE THE CURRENT UPPER-LEVEL WESTERLY FLOW OVER ANDRES...AND THE RUNS FROM TONIGHT DO NOT SEEM TO INITIALIZE THOSE WINDS WELL. THUS...THERE IS LESS THAN NORMAL CONFIDENCE IN THE LARGE-SCALE MODEL FORECASTS OF LIGHT SHEAR OVER ANDRES THROUGH 72 HR. SHOULD THE MODELS VERIFY...ANDRES WOULD BE DEEP EASTERLY FLOW...WHICH COULD ALLOW SIGNIFICANT DEVELOPMENT. ON THE OTHER HAND...IF THE SHEAR CONTINUES AND THE DRY AIR SEEN IN WATER VAPOR IMAGERY NEAR ANDRES ENTRAINS INTO THE SYSTEM...LITTLE OR NO DEVELOPMENT MAY OCCUR. THE INTENSITY FORECAST COMPROMISES BETWEEN THESE EXTREMES. IT CALLS FOR NO STRENGTHENING FOR THE FIRST 12 HR DUE TO THE CURRENT SHEAR...FOLLOWED BY GRADUAL STRENGTHENING THROUGH 72 HR. AFTER 72 HR...ANDRES SHOULD BE MOVING INTO COOLER WATERS AND SHOULD BEGIN WEAKENING. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 21/0900Z 9.7N 109.3W 35 KT 12HR VT 21/1800Z 9.8N 111.3W 35 KT 24HR VT 22/0600Z 10.3N 113.9W 40 KT 36HR VT 22/1800Z 11.0N 116.6W 45 KT 48HR VT 23/0600Z 11.8N 119.2W 50 KT 72HR VT 24/0600Z 13.5N 124.5W 55 KT 96HR VT 25/0600Z 15.0N 129.0W 45 KT 120HR VT 26/0600Z 16.0N 132.5W 30 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 16:49:55 UTC