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Tropical Depression ALEX


ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION ALEX DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012010
400 PM CDT SUN JUN 27 2010
 
SATELLITE IMAGES SHOW THAT ALEX CONTINUES TO HAVE A LARGE AND
WELL-DEFINED CIRCULATION WITH PLENTY OF BANDING FEATURES.  NEAR THE
CENTER...HOWEVER...CONVECTION HAS DECREASED...PROBABLY DUE TO THE
INFLUENCE OF LAND.  THE MEXICAN NAVY SURFACE STATION AT ISLA PEREZ
RECENTLY REPORTED 30 KT WINDS...SO THE INITIAL WIND SPEED IS KEPT
AT 30 KT.  AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS
SCHEDULED TO INVESTIGATE ALEX THIS EVENING AFTER THE CENTER MOVES
OFFSHORE. 
 
THE INITIAL MOTION OF ALEX IS A LITTLE SLOWER...WITH A 12-HR AVERAGE
YIELDING AN ESTIMATE OF 300/8.  THE PIVOTAL QUESTION FOR THE
LONG-TERM FORECAST TRACK OF THE TROPICAL CYCLONE APPEARS TO HINGE
ON THE STRENGTH OF MID-LEVEL RIDGING OVER THE NORTHERN GULF COAST. 
THE MODELS THAT SHOW A WEAKER RIDGE...SUCH AS THE CMC/GFS/HWRF...
ALLOW THE TROPICAL CYCLONE TO TURN TOWARD THE NORTH-NORTHWEST AND
NORTH AND APPROACH THE NORTHWESTERN GULF COAST IN SEVERAL DAYS. 
OTHER MODELS...SUCH AS THE ECMWF/UKMET/NOGAPS...HAVE A STRONGER
RIDGE AND KEEP ALEX MOVING TO THE NORTHWEST OR WEST-NORTHWEST INTO
MEXICO.  OVERALL THE MODEL GUIDANCE HAS SHIFTED SLIGHTLY TO THE
NORTH...AND THE OFFICIAL FORECAST IS A LITTLE TO THE RIGHT OF THE
PREVIOUS ONE. SINCE THERE IS CONSIDERABLE MODEL SPREAD...THIS TRACK
FORECAST IS THOUGHT TO BE OF BELOW-AVERAGE CONFIDENCE.
 
WHILE THERE IS A LARGE DISAGREEMENT ON THE TRACK OF ALEX...THE
GLOBAL MODELS ARE IN MUCH BETTER AGREEMENT WITH THE LARGE-SCALE
ENVIRONMENT. THESE MODELS SHOW AN UPPER-RIDGE AXIS SITTING VERY
NEAR THE TROPICAL CYCLONE FOR THE NEXT SEVERAL DAYS...IN A
FAVORABLE POSITION FOR INTENSIFICATION. COMBINED WITH THE WARM
WATERS OF THE GULF OF MEXICO...STRENGTHENING IS LIKELY...ESPECIALLY
AFTER ALEX MOVES FARTHER AWAY FROM THE YUCATAN PENINSULA. GIVEN THE
OVERALL ENVIRONMENTAL CONDITIONS...IT IS SURPRISING THAT THE
GFDL/HWRF DO NOT SHOW MORE INTENSIFICATION...LEAVING THE SYSTEM AS
A TROPICAL STORM FOR MANY DAYS. THE STATISTICAL GUIDANCE SEEMS MORE
REASONABLE AND THE NHC FORECAST IS CLOSE TO THE SHIPS MODEL...AND
IS NOT TOO DISSIMILAR FROM THE PREVIOUS FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/2100Z 19.2N  90.9W    30 KT
 12HR VT     28/0600Z 19.9N  91.8W    35 KT
 24HR VT     28/1800Z 20.6N  92.6W    45 KT
 36HR VT     29/0600Z 21.5N  93.3W    55 KT
 48HR VT     29/1800Z 22.3N  94.2W    65 KT
 72HR VT     30/1800Z 23.2N  96.3W    80 KT
 96HR VT     01/1800Z 24.0N  98.5W    55 KT...INLAND
120HR VT     02/1800Z 24.5N 100.5W    20 KT...DISSIPATING INLAND
 
$$
FORECASTER BLAKE
 
NNNN


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Page last modified: Friday, 15-Apr-2011 12:09:02 UTC