26W(NALGAE) intensifying and tracking over the Philippines//Invest 94W now on the map// 2803utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 26W(NALGAE).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL IMAGERY (MSI) OVER THE PAST SEVERAL HOURS INDICATES THAT DEEP CORE CONVECTION HAS BEGUN TO WRAP AROUND AN IMPROVING LOW LEVEL CIRCULATION CENTER (LLCC), WHILE PERSISTENT SUBSIDENCE IS KEEPING THE NORTHWESTERN QUADRANT LARGELY EXPOSED. THE LLCC IS DEVELOPING ON THE WESTERN EXTENT OF WHAT HAD BEEN A BROAD CIRCULATION, LEADING TO AN APPARENT ACCELERATION IN FORWARD MOTION. OCEAN SURFACE WIND VECTOR DATA (OSWV) REMAINS ELUSIVE YET AGAIN, HAMPERING ESTIMATES OF THE EXTENT OF 34 KNOT WINDS, BUT POSITIONING WAS PLACED BASED ON MULTI-AGENCY DVORAK ESTIMATES OF THE MSI INDICATED CENTER WITH MODERATE CONFIDENCE. A 272200Z SSMIS 91 GHZ PASS REVEALS INTENSE BANDING STRUCTURES WRAPPING ALONG THE SOUTHWESTERN AND SOUTHEASTERN FLANKS INTO A LARGE BUT DEFINED CENTER. THE INITIAL INTENSITY WAS MAINTAINED AT 40 KNOTS BASED ON AGENCY FIX ESTIMATES OF 30 TO 35 KNOTS, WITH CIMSS ADT AT 39 KNOTS AND A SATCON OF 38 KNOTS. EQUATORWARD OUTFLOW REMAINS ROBUST THANKS TO A POINT SOURCE TO THE SOUTH, AND VERTICAL WIND SHEAR IS FAVORABLE FOR ADDITIONAL DEVELOPMENT.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: NOW THAT THE LLCC IS TRACKABLE, IT IS APPARENT THAT TS NALGAE’S CURRENT POSITION REMAINS SOUTH OF PRIOR FORECASTS, AND IS PICKING UP SPEED AS IT MOVES CLOSER TO CENTRAL PHILIPPINES. AS A RESULT, THE CURRENT TRACK HAS SHIFTED SOUTH, WITH LANDFALL NOW EXPECTED BEFORE TAU 24 OVER THE BICOL REGION. THE SHORTENED TIMELINE SHOULD LIMIT FURTHER INTENSIFICATION TO A PEAK OF 60 KNOTS. TS 26W WILL TRACK NORTHWARD OVER SOUTHERN LUZON BEFORE ENTERING THE SOUTH CHINA SEA. A WEAKNESS IN THE STEERING RIDGE WILL RESULT IN A TURN TO THE NORTH BY TAU 72. MODEL GUIDANCE INDICATES THE TRACK WILL SLOW AFTER TAU 96 AS THE RIDGE RE-BUILDS AHEAD OF TRACK. THERE IS A GREAT DEAL OF UNCERTAINTY AT THIS POINT AS COMPETING STEERING INFLUENCES WILL DICTATE WHETHER NALGAE MOVES INTO NORTHEASTERLY SURGE FLOW AND BEGINS TO WEAKEN AND TURN TO THE NORTHWEST, OR WHETHER IT FOLLOWS THE EASTERN RIDGE ASSUMES CONTROL AND TAKES TS 26W TO THE NORTHEAST.

MODEL DISCUSSION: DETERMINISTIC MULTI-MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48, ALTHOUGH THERE IS SOME VARIABILITY IN TRACK SPEEDS. HOWEVER, AFTER THAT TIME THERE IS A BIFURCATION IN THE GUIDANCE AS DESCRIBED ABOVE. THE ECMWF AND GFS MODELS AND THEIR ENSEMBLE MEANS ARE FAVORING A TURN TO THE NORTHWEST AT THE END OF THE FORECAST. APPROXIMATELY TWO-THIRDS OF ALL ENSEMBLE MEMBERS FOLLOW THIS SOLUTION, WITH THE OTHER THIRD TRACKING TO THE NORTHEAST, BUT THE EVENTUAL OUTCOME IS JUST BEYOND THE END OF THE CURRENT FORECAST. INTENSITY GUIDANCE WAS LOWER THIS CYCLE DUE TO TIMING OF LANDFALL. THE CLEAR BIFURCATION IN MODEL GUIDANCE IN THE EXTENDED PERIOD ALONG WITH POSSIBLE INTERACTION WITH THE NORTHEAST SURGE EVENT LENDS LOW CONFIDENCE IN THE 72-120 HOUR JTWC TRACK AND INTENSITY FORECAST.

AN AREA OF CONVECTION (INVEST 94W) HAS PERSISTED NEAR 8.9N 141.3E, APPROXIMATELY 191 NM EAST OF YAP. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A BROAD AREA OF TURNING ASSOCIATED WITH FLARING CONVECTION. UPPER-LEVEL ANALYSIS INDICATES INVEST 94W IS IN MARGINALLY UNFAVORABLE CONDITIONS DUE TO HIGH VWS (25-40KTS) BUT IS OFFSET BY GOOD DIVERGENCE ALOFT. THE ENVIRONMENTAL ANALYSIS SHOWS FAVORABLE CONDITIONS WITH WARM SEA SURFACE TEMPERATURES (28-30C). GLOBAL MODEL GUIDANCE INDICATES A MORE GRADUAL INTENSIFICATION OF INVEST 94W, AS IT MEANDERS IN THE PHILIPPINE SEA THROUGH TAU 72. PREVIOUS MODEL RUNS WERE INDICATING A MORE AGGRESSIVE INTENSITY BUT HAVE SINCE BACKED OFF. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

GLOBAL MODEL GUIDANCE INDICATES A MORE GRADUAL INTENSIFICATION OF INVEST 94W, AS IT MEANDERS IN THE PHILIPPINE SEA THROUGH TAU 72. PREVIOUS MODEL RUNS WERE INDICATING A MORE AGGRESSIVE INTENSITY BUT HAVE SINCE BACKED OFF.