WTPZ44 KNHC 250232 RRA

TCDEP4



TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   1

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042017

1000 PM CDT SAT JUN 24 2017



SATELLITE IMAGES INDICATE THAT THE LOW PRESSURE SYSTEM SOUTH OF

MEXICO HAS A WELL-DEFINED CIRCULATION WITH CONVECTIVE BANDING

FEATURES DEVELOPING NEAR THE CENTER.  THE CONVECTION APPEARS TO

HAVE ENOUGH ORGANIZATION TO CLASSIFY THE SYSTEM AS A TROPICAL

CYCLONE, AND THE INITIAL INTENSITY IS SET AT 25 KT BASED ON DVORAK

ESTIMATES OF T2.0 FROM TAFB AND T1.5 FROM SAB.



THE DEPRESSION IS LOCATED TO THE SOUTHWEST OF A CLOSED MID-/

UPPER-LEVEL LOW LOCATED OVER THE WESTERN GULF OF MEXICO, AND TO THE

SOUTHEAST OF A LARGE MID-TROPOSPHERIC HIGH CENTERED OVER ARIZONA.

THE INITIAL MOTION IS WEST-NORTHWESTWARD, OR 300/9 KT, AND THIS

GENERAL MOTION SHOULD CONTINUE FOR THE NEXT THREE DAYS AS THE

DEPRESSION IS INCREASINGLY STEERED BY THE STRONG HIGH PRESSURE TO

ITS NORTH.  SOME DECREASE IN SPEED IS LIKELY BY DAYS 4 AND 5 ONCE

THE CYCLONE WEAKENS AND IS STEERED BY LOWER-LEVEL WINDS.  THE TRACK

MODELS ARE SHOWING RELATIVELY LITTLE CROSS-TRACK SPREAD, BUT THERE

ARE SOME SPEED DIFFERENCES, WITH THE ECMWF MOST NOTABLY BEING SLOWER

THAN THE OTHER GUIDANCE.  THE NHC OFFICIAL TRACK FORECAST IS

RELATIVELY CLOSE TO THE MULTI-MODEL CONSENSUS TVCN, AND THERE IS

HIGH CONFIDENCE THAT THE CYCLONE WILL MOVE PARALLEL TO THE COAST OF

MEXICO, KEEPING THE TROPICAL-STORM-FORCE WINDS WELL OFFSHORE.



WATER VAPOR IMAGERY SHOWS THE DEPRESSION'S OUTFLOW EXPANDING IN

NEARLY ALL DIRECTIONS, AND DEEP-LAYER SHEAR IS FORECAST TO BE VERY

LOW FOR THE ENTIRE FORECAST PERIOD.  THEREFORE, STRENGTHENING IS