Tropical Depression ONE-E

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TROPICAL DEPRESSION ONE-E DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP012007
200 AM PDT SUN MAY 27 2007
 
THE TROPICAL DEPRESSION IS SENDING MIXED MESSAGES THIS MORNING.  AN
EARLIER QUIKSCAT PASS AT 0146 UTC SHOWED SEVERAL BELIEVABLE WIND
SPEEDS JUST BELOW STORM STRENGTH.  A LITTLE LATER...AT 0338 UTC...
SSMIS MICROWAVE DATA SHOWED A CURVED BAND STRUCTURE AROUND THE
CENTER.  HOWEVER...SINCE THESE MICROWAVE DATA...THE CONVECTIVE
ORGANIZATION OF THE SYSTEM HAS BEEN DETERIORATING.  AN EARLIER
IMPRESSIVE BAND TO THE SOUTH OF THE CENTER HAS BEEN DRAMATICALLY
WEAKENING.  THE CENTER...AS DERIVED FROM EARLIER MICROWAVE
PASSES...NOW SEEMS TO BE ON THE NORTHERN SIDE OF THE REMAINING DEEP
CONVECTION.  IT IS A LITTLE ODD THAT THUNDERSTORMS ARE
PREFERENTIALLY FORMING ON THE SOUTHEASTERN PORTION OF THE
CIRCULATION WHEN THE SHEAR IS COMING FROM THE SOUTHEAST...PERHAPS
INDICATIVE OF THE GENERAL LACK OF ORGANIZATION AT THIS TIME.  IN
ANY EVENT...SATELLITE CLASSIFICATIONS REMAIN BELOW TROPICAL STORM
STRENGTH AND THE INITIAL INTENSITY WILL STAY AT 30 KT.
 
FOR THE MOMENT...WITH THE CENTER ON THE NORTHERN PART OF THE
CONVECTIVE MASS...ANY INTENSIFICATION IS TEMPORARILY HALTED. 
HOWEVER WATER VAPOR IMAGES SHOW THAT THE DEPRESSION IS UNDER THE
INFLUENCE OF UPPER RIDGING WITH ONLY MODEST SOUTHEASTERLY SHEAR. 
THIS PATTERN SHOULD ALLOW FOR MORE STRENGTHENING LATER ON AS
A LOW TO MODERATE SHEAR ENVIRONMENT IS FORECAST TO PERSIST FOR
AT LEAST 3 DAYS BY THE GLOBAL MODELS.  IN ADDITION...SSTS WILL
REMAIN PLENTY WARM...SO INTENSIFICATION IS FORECAST.  THE ONLY
OBVIOUS NEGATIVE FOR FURTHER DEVELOPMENT IS THE ENTRAINMENT OF MORE
STABLE AIR INTO THE NORTHERN PORTION OF THE CIRCULATION...WHICH
SHOULD BE MINIMIZED IF THE CYCLONE CONTINUES MOVING WESTWARD.
VERTICAL WIND SHEAR COULD INCREASE BEYOND THREE DAYS SO THE
INTENSITY FORECAST WILL BE NUDGED DOWNWARD AT THAT TIME-FRAME.
 
THE INITIAL MOTION ESTIMATE IS WESTWARD...270/4. A MIDDLE- TO
UPPER-LEVEL TROUGH OVER MEXICO HAS PASSED THE DEPRESSION AND LEFT
IT IN AN AREA OF WEAK STEERING CONDITIONS. RIDGING TO THE NORTHWEST
OF THE SYSTEM SHOULD STEER IT SLOWLY WESTWARD FOR A COUPLE DAYS.
THEREAFTER...UPPER RIDGING IS FORECAST TO BUILD TO THE NORTH OF THE
DEPRESSION...WHICH SHOULD ENCOURAGE A FASTER WESTWARD MOTION. THIS
IS THE APPROXIMATE SOLUTION PRESENTED BY THE ECMWF AND THE CANADIAN
MODEL. HOWEVER... OTHER GLOBAL MODELS HAVE SLOWER SOLUTIONS...
SEEMINGLY STRUGGLING WITH AN AREA OF DISTURBED WEATHER TO THE EAST
OF THE DEPRESSION. THE GFS... NOGAPS AND UKMET (TO SOME EXTENT)
FORECAST THAT THE SYSTEM BEHIND THE DEPRESSION WILL BECOME LARGER
AND STRONGER RATHER QUICKLY... WHICH SLOWS THE MOTION OF THE
DEPRESSION. FOR NOW...GIVEN THE RELATIVE BENIGN APPEARANCE ON
SATELLITE OF THE SECOND SYSTEM...A FASTER SOLUTION WILL BE FAVORED.
THE OFFICIAL FORECAST IS SLOWER THAN THE PREVIOUS FORECAST PACKAGE
BUT FASTER THAN MOST OF THE GUIDANCE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/0900Z 12.8N 111.2W    30 KT
 12HR VT     27/1800Z 12.8N 111.8W    30 KT
 24HR VT     28/0600Z 12.8N 112.6W    40 KT
 36HR VT     28/1800Z 12.8N 113.4W    45 KT
 48HR VT     29/0600Z 12.8N 114.2W    50 KT
 72HR VT     30/0600Z 12.8N 116.0W    55 KT
 96HR VT     31/0600Z 12.8N 118.0W    55 KT
120HR VT     01/0600Z 12.8N 120.5W    50 KT
 
$$
FORECASTER BLAKE
 
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