|
Show Selection: |
| #163472 (Received by flhurricane at: 3:46 AM 12.Dec.2007) TCDAT2 TROPICAL STORM OLGA DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172007 400 AM EST WED DEC 12 2007 OLGA HAS LOST SOME ORGANIZATION DURING ITS CROSSING OF HISPANIOLA. THERE IS NO SIGNIFICANT CONVECTION NEAR THE CENTER AT THIS TIME... AND THE CONVECTIVE BANDS OVER THE ATLANTIC TO THE NORTH OF HISPANIOLA ARE RELATIVELY WEAK. THERE ARE NO RECENT OBSERVATIONS FROM NEAR THE CENTER OR FROM THE MAIN AREA OF CONVECTION....SO THE INITIAL INTENSITY REMAINS 45 KT ON THIS ADVISORY. THIS MAY BE GENEROUS. THE INITIAL MOTION IS 275/16. OLGA IS CURRENTLY ON THE SOUTH SIDE OF A LOW/MID-LEVEL RIDGE OVER THE WESTERN ATLANTIC...FLORIDA...AND THE EASTERN GULF OF MEXICO. THE LARGE-SCALE MODELS FORECAST THE WESTERN END OF THE RIDGE TO GRADUALLY WEAKEN DURING THE NEXT 2-3 DAYS IN ADVANCE OF A DEEP-LAYER TROUGH AND ASSOCIATED COLD FRONT MOVING THROUGH THE EASTERN UNITED STATES ON DAYS 4-5. THIS PATTERN EVOLUTION HAS CAUSED THE TRACK GUIDANCE TO SPLIT INTO TWO CAMPS AFTER OLGA MOVES WESTWARD FOR 24-48 HR. THE GLOBAL MODELS FORECAST OLGA...OR ITS REMNANTS...TO TURN NORTHWARD AND RECURVE INTO THE COLD FRONT MOVING ACROSS THE GULF OF MEXICO. ON THE OTHER HAND... THE GFDL AND HWRF FORECAST OLGA TO TURN SOUTHWEST TOWARDS THE GULF OF HONDURAS. THIS FORECAST MAY BE DUE TO THOSE MODELS KEEPING MORE RIDGING WEST OF OLGA OVER THE YUCATAN PENINSULA...AND FORECASTING A STRONG CYCLONE IN AN ENVIRONMENT OF UPPER-LEVEL NORTHWESTERLY FLOW. THE NEW FORECAST TRACK IS ADJUSTED NORTH OF THE PREVIOUS TRACK... BUT WILL NOT YET CALL FOR RECURVATURE IN DEFERENCE TO THE GFDL... HWRF...AND THE PREVIOUS FORECAST. THE NEW TRACK IS A LITTLE TO THE SOUTH OF THE VARIOUS CONSENSUS MODELS. THE DYNAMICAL MODELS AGREE THAT THE UPPER-LEVEL LOW/TROUGH THAT HAS SO FAR PROTECTED OLGA FROM SHEAR WILL WEAKEN DURING THE NEXT 24 HR AS A RIDGE BUILDS OVER THE WESTERN CARIBBEAN. THIS SHOULD CAUSE STRONG NORTHWESTERLY VERTICAL WIND SHEAR TO DEVELOP OVER THE SYSTEM. THE INTENSITY FORECAST IS THUS UNCHANGED FROM THE PREVIOUS ADVISORY...CALLING FOR OLGA TO WEAKEN TO A DEPRESSION IN 24 HR AND TO A REMNANT LOW IN 36 HR. IT SHOULD BE NOTED THAT THE GFDL AND HWRF FORECAST OLGA TO MOVE INTO AN AREA OF LIGHTER WIND SHEAR IN THE GULF OF HONDURAS...AND IN CONSEQUENCE BOTH MODELS FORECAST IT TO BECOME A HURRICANE. IT SHOULD ALSO BE NOTED THAT THE SHEAR IS FORECAST TO BE VERY STRONG OVER THE GULF OF MEXICO...SO THE CHANCES OF OLGA BEING A SIGNIFICANT TROPICAL CYCLONE IN THAT AREA APPEAR RATHER LOW AT THE MOMENT. THE PRIMARY THREAT FROM OLGA CONTINUES TO BE HEAVY RAINFALL AND LIFE-THREATENING FLASH FLOODS AND MUD SLIDES IN PUERTO RICO AND HISPANIOLA. THESE RAINS SHOULD BEGIN TO SPREAD OVER EASTERN CUBA TODAY. FORECAST POSITIONS AND MAX WINDS INITIAL 12/0900Z 19.2N 72.5W 45 KT...INLAND 12HR VT 12/1800Z 19.4N 74.9W 35 KT...OVER WATER 24HR VT 13/0600Z 19.6N 77.7W 30 KT 36HR VT 13/1800Z 19.8N 79.6W 25 KT...REMNANT LOW 48HR VT 14/0600Z 20.0N 81.5W 25 KT...REMNANT LOW 72HR VT 15/0600Z 20.5N 84.0W 25 KT...REMNANT LOW 96HR VT 16/0600Z...DISSIPATED $$ FORECASTER BEVEN |
