000 WTNT44 KNHC 211444 TCDAT4 TROPICAL STORM RICHARD DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL192010 1100 AM EDT THU OCT 21 2010 AIRCRAFT DATA FROM THE AIR FORCE RESERVE HURRICANE HUNTERS SHOWED PEAK FLIGHT WINDS OF 40 KT...RELIABLE SFMR VALUES OF 37 KT...AND A MINIMUM PRESSURE OF ABOUT 1006 MB. BASED ON THE ABOVE DATA...THIS SYSTEM IS UPGRADED TO A TROPICAL STORM WITH AN INITIAL INTENSITY OF 35 KT. THE CENTER IS LOCATED JUST TO THE WEST OF INCREASING MASS OF THUNDERSTORMS...WITH A WEAK LOW-LEVEL SWIRL SEEN FARTHER TO THE SOUTHWEST IN THE HIGH RESOLUTION VISIBLE IMAGES. OVERALL...THE CLOUD PATTERN HAS BECOME MORE CONCENTRATED NEAR THE CENTER...WITH MANY CURVED BANDS IN THE EASTERN SEMICIRCLE. GRADUAL INTENSIFICATION SEEMS TO BE THE BEST BET IN THE SHORT-TERM. WHILE SHEAR HAS DECREASED FROM YESTERDAY...THERE IS STILL A FAIR AMOUNT OF MID- TO UPPER-LEVEL DRY AIR PRESENT TO THE NORTHWEST OF THE CYCLONE. THIS DRY AIR WILL HAVE A DECENT CHANCE OF SLOWING THE STRENGTHENING RATE FOR THE NEXT DAY OR SO AS IT CONTINUES TO BE ADVECTED TOWARD THE TROPICAL CYCLONE BY A TROUGH OVER THE EXTREME NORTHWESTERN CARIBBEAN SEA ACROSS FLORIDA. HOWEVER...IN A COUPLE OF DAYS...UPPER-LEVEL RIDGING IS FORECAST TO BUILD OVER THE CYCLONE... CREATING A RATHER LOW SHEAR ENVIRONMENT...WHICH SHOULD CUT DOWN ON ANY DRY AIR ENTRAINMENT. THE NHC INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE THROUGH 48 HOURS...THEN IS HIGHER THEREAFTER. THE NEW FORECAST IS BETWEEN THE STATISTICAL MODELS AND THE INTENSITY MODEL CONSENSUS. IT IS WORTH NOTING THAT THE GFDL AND HWRF STRENGTHEN THIS SYSTEM INTO A MAJOR HURRICANE IN A FEW DAYS...WHICH IS NOT OUT OF QUESTION IF RICHARD DEVELOPS THE RIGHT INNER CORE STRUCTURE. THE STORM HAS BEEN ERRATICALLY MOVING DURING MOST OF ITS LIFE...AND A LONG-TERM MOTION IS ABOUT 135/5. CURRENTLY RICHARD IS UNDERGOING AN ANTICYCLONIC LOOP AS IT IS CAUGHT IN AN AREA OF RELATIVELY LIGHT STEERING BETWEEN A TROUGH TO THE NORTH AND A DISTANT RIDGE OVER THE TROPICAL ATLANTIC. BY LATE TOMORROW...RIDGING SHOULD REBUILD OVER THE GULF OF MEXICO...WHICH SHOULD CAUSE THE SYSTEM TO MOVE MORE TO THE WEST...AND EVENTUALLY WEST-NORTHWEST TO NORTHWEST IN A FEW DAYS. THE STRENGTH OF THE RIDGE OVER THE GULF OF MEXICO APPEARS TO BE THE KEY FEATURE IN THE LONG-RANGE FORECAST. GENERALLY THE GLOBAL MODELS WITH A STRONG RIDGE...SUCH AS THE GFS/NOGAPS...KEEP RICHARD ON A MORE NORTHWESTERLY HEADING WHEN THE CYCLONE APPROACHES THE GULF OF MEXICO. HOWEVER...THE MODELS WITH A WEAKER RIDGE...SUCH AS THE UKMET/ECMWF...AND TO AN EXTREME DEGREE THE HWRF/GFDL...SHOW THE RIDGE BEING ERODED RATHER QUICKLY AS A NEW UPSTREAM TROUGH DIVES INTO THE CENTRAL PLAINS. THE BULK OF THE GUIDANCE IS NOW SUGGESTING THE WEAKER RIDGE IS MORE LIKELY...AND THE NHC FORECAST IS SHIFTED TO THE NORTHEAST AT DAYS 4 AND 5. CONSIDERING THAT THE NEW FORECAST IS STILL ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE... FURTHER NORTHEASTWARD ADJUSTMENTS MAY BE REQUIRED IF CURRENT MODEL TRENDS CONTINUE. FORECAST POSITIONS AND MAX WINDS INITIAL 21/1500Z 16.2N 80.4W 35 KT 12HR VT 22/0000Z 16.0N 80.4W 40 KT 24HR VT 22/1200Z 15.9N 80.9W 50 KT 36HR VT 23/0000Z 16.0N 81.6W 55 KT 48HR VT 23/1200Z 16.2N 82.4W 65 KT 72HR VT 24/1200Z 17.4N 85.2W 80 KT 96HR VT 25/1200Z 19.5N 88.0W 45 KT...INLAND 120HR VT 26/1200Z 22.0N 89.0W 35 KT...OVER WATER $$ FORECASTER BLAKE