WTPZ42 KNHC 171445 RRA

TCDEP2



TROPICAL DEPRESSION SEVEN-E DISCUSSION NUMBER   1

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072017

1000 AM CDT MON JUL 17 2017



RECENT SATELLITE DATA INDICATE THAT THE AREA OF LOW PRESSURE LOCATED

SEVERAL HUNDRED MILES SOUTH OF MANZANILLO, MEXICO, HAS ACQUIRED A

WELL-DEFINED CENTER AND THE ASSOCIATED DEEP CONVECTION IS

SUFFICIENTLY ORGANIZED FOR THE SYSTEM TO BE CLASSIFIED AS A TROPICAL

DEPRESSION.  THIS MARKS THE FORMATION OF THE SEVENTH CYCLONE OF THE

EASTERN PACIFIC HURRICANE SEASON.  THE SYSTEM IS SHEARED WITH THE

CENTER LOCATED NEAR THE NORTHWESTERN EDGE OF THE PRIMARY CONVECTIVE

MASS.  EARLIER ASCAT DATA REVEALED BELIEVABLE 25-30 KT WINDS, AND

THE INITIAL INTENSITY IS SET TO 30 KT.  THE ENVIRONMENT AHEAD OF

THE CYCLONE IS NOT IDEAL FOR SIGNIFICANT STRENGTHENING.  MODERATE TO

STRONG NORTHWESTERLY SHEAR IS EXPECTED TO CONTINUE FOR ANOTHER 24

HOURS, BUT IS THEN FORECAST TO LESSEN LATE TUESDAY WHEN THE SYSTEM

IS LOCATED IN A COL AREA BETWEEN TWO LARGE UPPER LEVEL LOWS.

THE SHEAR IS EXPECTED TO BECOME QUITE STRONG BY DAY 4 WHEN THE

CYCLONE APPROACHES THE WESTERNMOST UPPER LOW/TROUGH.  THIS SHEAR,

ALONG WITH COOLER WATERS, SHOULD CAUSE WEAKENING LATE IN THE PERIOD.



THE SOMEWHAT UNCERTAIN INITIAL MOTION ESTIMATE IS 280/5 KT. THE

DEPRESSION IS FORECAST TO MOVE WESTWARD TO WEST-NORTHWESTWARD TO THE

SOUTH OF A MID-LEVEL RIDGE LOCATED OVER NORTHERN MEXICO AND THE

WESTERN UNITED STATES.  THE TRACK GUIDANCE IS IN RELATIVELY GOOD

AGREEMENT THROUGH 72 HOURS, BUT THERE IS SIGNIFICANT SPREAD AFTER

THAT TIME, DUE TO POSSIBLE INTERACTION WITH A DISTURBANCE CURRENTLY

LOCATED ABOUT 750 N MI WEST OF THE DEPRESSION.  THE ECMWF TAKES THE