WTPZ42 KNHC 191442 RRA

TCDEP2



TROPICAL STORM GREG DISCUSSION NUMBER   9

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072017

900 AM MDT WED JUL 19 2017



EARLIER MICROWAVE DATA INDICATE THAT THE CENTER OF GREG WAS LOCATED

NEAR THE NORTHWESTERN EDGE OF THE MAIN CONVECTIVE CLOUD SHIELD.

HOWEVER, RECENT EARLY-LIGHT VISIBLE SATELLITE IMAGES SUGGEST THE

SYSTEM IS BEGINNING TO BECOME BETTER ORGANIZED WITH THE CENTER

EMBEDDED BENEATH THE COLD CLOUD TOPS AND INCREASED BANDING OVER THE

WESTERN PORTION OF THE CIRCULATION.  SUBJECTIVE AND OBJECTIVE DVORAK

SATELLITE ESTIMATES RANGE FROM 43 KT TO 55 KT, BUT THE INITIAL

INTENSITY WILL REMAIN 40 KT, IN DEFERENCE TO THE OVERNIGHT ASCAT

DATA WHICH INDICATED THAT PEAK WINDS WERE LOWER THAN THE DVORAK

ESTIMATES.



THE SHEAR THAT HAS BEEN AFFECTING THE TROPICAL CYCLONE DURING THE

PAST COUPLE OF DAYS APPEARS TO BE DECREASING.  THIS IS EXPECTED TO

ALLOW STRENGTHENING WHILE GREG MOVES OVER WARM SSTS AND THROUGH A

HIGH MOISTURE ENVIRONMENT.  THE INTENSITY GUIDANCE IS A BIT HIGHER

THAN BEFORE, WITH THE HWRF, HCCA, AND SHIPS GUIDANCE MAKING GREG A

HURRICANE IN 2 TO 3 DAYS.  THE NHC FORECAST IS A LITTLE MORE

CONSERVATIVE AND SLIGHTLY BELOW THE MODEL CONSENSUS LATE IN THE

PERIOD DUE TO UNCERTAINTIES REGARDING THE POTENTIAL INTERACTION

WITH TD EIGHT-E.  THE GLOBAL MODELS HAVE TRENDED OVER THE PAST 24

HOURS OF INDICATING GREG WILL BECOME THE DOMINATE CYCLONE.  IF THESE

TRENDS CONTINUE, ADDITIONAL UPWARD ADJUSTMENTS TO THE NHC INTENSITY

FORECAST MAY BE NEEDED.



GREG IS MOVING WESTWARD OR 270/9 KT. A MID- TO UPPER-LEVEL RIDGE

EXTENDING WESTWARD FROM NORTHWESTERN MEXICO SHOULD STEER THE