Tropical Depression Sixteen in the SW Caribbean Sea

The system known as TD-16 may effect the region on the weekend. As such I am starting to keep track of system on the blog now.

000


WTNT41 KNHC 290242

TCDAT1

TROPICAL DEPRESSION SIXTEEN DISCUSSION NUMBER 3

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL162010

1100 PM EDT TUE SEP 28 2010



TROPICAL DEPRESSION SIXTEEN CONTINUES TO HAVE A STRUCTURE MORE

CHARACTERISTIC OF A WESTERN NORTH PACIFIC/NORTH INDIAN OCEAN

MONSOON DEPRESSION. SURFACE OBSERVATIONS CONTINUE TO INDICATE

WINDS OF 20 KT OR LESS OVER AN AREA ENCOMPASSING 100 N MI IN

DIAMETER FROM THE CENTER...AND THAT THE STRONGEST WINDS AND

CONVECTION ARE 250-300 N MI AWAY FROM THE CENTER IN THE

SOUTHEASTERN QUADRANT. AN EARLIER AIR FORCE RESERVE HURRICANE

HUNTER MISSION IN THIS AREA FOUND FLIGHT-LEVEL WINDS SUPPORTING AN

INITIAL INTENSITY OF 30 KT. SURFACE OBSERVATIONS INDICATE THAT THE

CENTRAL PRESSURE IS NEAR 997 MB.



THERE ARE MULTIPLE LOW-LEVEL CLOUD SWIRLS PRESENT...AND THE CENTER

APPEARS TO RE-FORM FROM TIME TO TIME. THE INITIAL MOTION OF 035/7

IS THUS A BIT UNCERTAIN. OTHER THAN THAT...THERE IS NO CHANGE IN

THE FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY...AND ONLY MINOR

CHANGES TO THE FORECAST TRACK. A COMBINATION OF A DEEP-LAYER

TROUGH OVER THE SOUTHEASTERN UNITED STATES AND EASTERN GULF OF

MEXICO AND A LOW/MID-LEVEL RIDGE OVER THE WESTERN ATLANTIC SHOULD

STEER THE CYCLONE NORTH-NORTHEASTWARD WITH ACCELERATION FOR THE

NEXT 12-24 HOURS...FOLLOWED BY A QUICK NORTHWARD MOTION. THERE IS

SOME SPREAD IN BOTH THE SPEED AND DIRECTION OF MOTION BY 48 HR.

THE GFS... GFDL...AND HWRF ARE MUCH FASTER AND TO THE LEFT OF THE

REST OF THE GUIDANCE...WHILE THE NOGAPS...GFDN...AND GFS ENSEMBLE

MEAN ARE SLOWER AND TO THE RIGHT. THESE DIFFERENCES LIKELY RESULT

FROM THE MODEL HANDLING OF THE DEPRESSION INTERACTING WITH A

DEVELOPING BAROCLINIC LOW OVER THE EASTERN UNITED STATES. THE NEW

FORECAST TRACK IS DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE CLOSE TO

THE CONSENSUS MODELS.



THE DEPRESSION IS CURRENTLY IN AN ENVIRONMENT OF 15 KT OF

SOUTHWESTERLY VERTICAL WIND SHEAR...WHICH THE LARGE-SCALE MODELS

FORECAST TO INCREASE DURING THE NEXT 12-24 HR. THUS...NEITHER THE

ENVIRONMENT NOR THE CURRENT STRUCTURE ARE CONDUCIVE FOR SIGNIFICANT

STRENGTHENING. THE INTENSITY FORECAST IS THE SAME AS IN THE

PREVIOUS ADVISORY...WITH MODEST STRENGTHENING ALONG THE LINES OF

THE SHIPS AND LGEM MODELS. EXTRATROPICAL TRANSITION IS EXPECTED TO

BEGIN IN ABOUT 24 HR OR SO AND BE COMPLETE BY 36-48 HR. THE

CYCLONE IS FORECAST TO BE ABSORBED BY THE EASTERN U. S. BAROCLINIC

LOW AFTER 48 HR...AS FORECAST BY MOST OF THE DYNAMICAL GUIDANCE.



UNLESS THE STRUCTURE CHANGES RADICALLY IN THE NEXT 12-24 HOURS...IT

IS LIKELY THAT THERE WILL CONTINUE TO BE A LARGE AREA OF LIGHT

WINDS NEAR THE CENTER. THE STRONGEST WINDS SHOULD OCCUR IN AREAS

WELL TO THE EAST OF THE FORECAST TRACK.



FORECAST POSITIONS AND MAX WINDS



INITIAL 29/0300Z 21.9N 81.9W 30 KT

12HR VT 29/1200Z 23.3N 81.2W 35 KT

24HR VT 30/0000Z 26.3N 80.2W 40 KT

36HR VT 30/1200Z 30.6N 79.3W 40 KT...POST-TROP/EXTRATROP

48HR VT 01/0000Z 36.3N 78.0W 35 KT...POST-TROP/EXTRATROP

72HR VT 02/0000Z...ABSORBED BY EXTRATROPICAL LOW



$$

FORECASTER BEVEN