Flhurricane.com - Central Florida Hurricane Center - Tracking Storms since 1995Hurricanes Without the Hype! Since 1995
The Atlantic is quiet
|
Show Selection: |
| #549806 (Received by flhurricane at: 10:44 AM 13.Oct.2012) TCDAT2 TROPICAL STORM RAFAEL DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172012 1100 AM AST SAT OCT 13 2012 THE SATELLITE PRESENTATION OF RAFAEL HAS BEGUN TO IMPROVE A LITTLE...WITH DEEP CONVECTION MOVING A LITTLE CLOSER TO THE CENTER AS THE UPPER-LEVEL LOW THAT HAS BEEN PRODUCING STRONG SOUTHWESTERLY SHEAR OVER THE CYCLONE BEGINS TO LIFT NORTHWARD. DATA FROM THE LATEST AIRCRAFT MISSION SUGGEST THAT THE PEAK WINDS ARE NO HIGHER THAN 35 KT...WITH THE CENTRAL PRESSURE REMAINING 1006 MB. GLOBAL MODELS AND THE SHIPS MODEL DIAGNOSTICS SUGGEST THAT THE SHEAR WILL CONTINUE TO DECREASE OVER THE NEXT DAY OR SO...WHICH SHOULD ALLOW THE CYCLONE TO BEGIN STRENGTHENING GRADUALLY. MOST OF THE GUIDANCE SHOWS INTENSIFICATION CONTINUING THROUGH 72 HOURS DESPITE SOUTHWESTERLY SHEAR INCREASING TO MODERATE VALUES BY THAT TIME... AND THE OFFICIAL FORECAST SHOWS RAFAEL BECOMING A HURRICANE IN ABOUT 3 DAYS. LATE IN THE PERIOD THE SHEAR INCREASES ABOVE 40 KT...WHICH SHOULD RESULT IN SOME WEAKENING AS THE CYCLONE BECOMES EXTRATROPICAL. THE NEW NHC FORECAST IS A LITTLE HIGHER THAN THE PREVIOUS ONE...CLOSE TO THE LATEST INTENSITY CONSENSUS AIDS THROUGH 48 HOURS...AND A LITTLE LOWER THAN THE CONSENSUS AFTER THAT TIME. THE LATEST AIRCRAFT FIXES SUGGEST THAT THE CENTER IS LOCATED A LITTLE TO THE EAST OF PREVIOUS ESTIMATES...AND THE INITIAL MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 330/08. EARLY IN THE PERIOD THERE IS SOME SIZEABLE SPREAD IN THE GUIDANCE. THE GFS SHOWS A DUE NORTHWARD MOTION AS IT MAINTAINS THE UPPER-LOW WEST OF RAFAEL A LITTLE LONGER WHILE THE ECMWF AND UKMET WEAKEN THE LOW FASTER AND SHOW A MORE NORTHWESTWARD MOTION. THE OFFICIAL FORECAST TRACK LIES IN BETWEEN...SHOWING A NORTH-NORTHWESTWARD MOTION IN THE FIRST 24 HOURS FOLLOWED BY A SLIGHT LEFT TURN ON DAY 2 AS A MID-LEVEL RIDGE REBUILDS TO THE NORTHEAST OF RAFAEL. THE NHC FORECAST DURING THIS TIME REMAINS CLOSE TO THE PREVIOUS TRACK AND IS A LITTLE TO THE LEFT OF THE MIDDLE OF THE GUIDANCE ENVELOPE. LATE IN THE PERIOD THE TRACK UNCERTAINTY GROWS LARGER. THE GFS REMAINS A FAST OUTLIER COMPARED TO THE OTHER GLOBAL MODELS AND THE GEFS ENSEMBLE MEAN... SHOWING RAFAEL ACCELERATING NORTHWARD AHEAD OF A CUTOFF LOW OVER THE NORTHEASTERN UNITED STATES. THIS SCENARIO IS ALSO SHOWN BY THE GFDL AND HWRF...WHOSE LARGE-SCALE FIELDS ARE DRIVEN BY THE GFS OUTPUT. ON THE OTHER HAND BOTH THE ECMWF AND UKMET SHOW RAFAEL INTERACTING WITH A SHORTWAVE TROUGH THAT MOVES OFF THE SOUTHEAST U.S. COAST AND INDICATE A SLOWER NORTHEASTWARD MOTION. THE NHC FORECAST DURING DAYS 3 THROUGH 5 REMAINS TO THE RIGHT OF AND SLOWER THAN MULTI- MODEL CONSENSUS...GIVEN THAT THE GFS APPEARS TO BE A LEFT OUTLIER COMPARED TO EVEN ITS OWN ENSEMBLE MEAN. NEEDLESS TO SAY... CONFIDENCE IS QUITE LOW IN THE EXTENDED PORTION OF THE FORECAST PERIOD...WITH THE 96-HOUR POSITIONS OF THE GFS AND ECMWF MORE THAN 800 MILES APART. USERS ARE REMINDED NOT TO FOCUS ON THE EXACT TRACK OF THE CENTER DURING THE NEXT DAY OR SO...SINCE HEAVY RAIN AND WIND IMPACTS EXTEND WELL EAST AND SOUTHEAST OF THE CENTER. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 15.9N 64.1W 35 KT 40 MPH 12H 14/0000Z 17.4N 64.6W 40 KT 45 MPH 24H 14/1200Z 19.2N 65.2W 50 KT 60 MPH 36H 15/0000Z 21.0N 66.2W 55 KT 65 MPH 48H 15/1200Z 22.6N 67.0W 60 KT 70 MPH 72H 16/1200Z 28.0N 66.0W 65 KT 75 MPH 96H 17/1200Z 38.0N 61.0W 55 KT 65 MPH 120H 18/1200Z 45.0N 54.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ FORECASTER BRENNAN |
