WTPA41 PHFO 212052 RRA

TCDCP1



TROPICAL STORM FERNANDA DISCUSSION NUMBER  40

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP062017

1100 AM HST FRI JUL 21 2017



FERNANDA PRESENTS POORLY IN SATELLITE IMAGERY. DEEP CONVECTION

REMAINS WITHIN THE NORTHEAST QUADRANT OF FERNANDA'S LOW LEVEL

CIRCULATION CENTER (LLCC), RANGING FROM 40 TO 110 NM, AS THIS SYSTEM

FEELS THE EFFECTS OF STRONG SOUTHWESTERLY SHEAR. SUBJECTIVE DVORAK

SATELLITE INTENSITY ESTIMATES RANGE FROM 25 KT, FROM SAB, TO 35 KT,

FROM PHFO. UW-CIMSS PROVIDED AN ADT INTENSITY OF 25 KT. IT IS TOO

EARLY FOR A TIMELY ASCAT PASS, SO WE WILL ASSIGN A POTENTIALLY

GENEROUS 35 KT AS THE INITIAL SYSTEM INTENSITY IN KEEPING WITH THE

OVERALL POOR APPEARANCE AND CONTINUED WEAKENING TREND.



INITIAL MOTION IS 280/07KT, REPRESENTING A BIT OF SLOWING OVER THE

PAST 12 HOURS, AS FERNANDA MOVES WESTWARD ALONG THE SOUTHERN FLANK

OF THE SUBTROPICAL RIDGE. A WEAKNESS IN THE RIDGE WEST OF 160W

CONTINUES TO ALLOW FERNANDA TO GAIN LATITUDE, ALTHOUGH QUITE

SLOWLY. TRACK QUIDANCE, ONCE THE UNREPRESENTITIVE GFS AND ITS

ASSOCIATED BLENDS ARE REMOVED, IS RATHER TIGHT, DEPICTING A SHALLOW

SYSTEM MOVING GENERALLY WESTWARD TO WEST NORTHWESTWARD WITHIN LOW

LEVEL STEERING FLOW. THE FORECAST TRACK CLOSELY FOLLOWS THE

PREVIOUS ONE, BUT IS NUDGED EVER SO SLIGHTLY TO THE LEFT AT 24 AND

36 HOURS TO ACCOUNT FOR THE ECMWF LEFTWARD SHIFT THROUGH THOSE

TIMES. THE 48 HOUR FORECAST IS ALMOST UNCHANGED, WITH SYSTEM

DISSIPATION EXPECTED AFTERWARD. NOTE THAT ON THIS FORECAST TRACK,

FERNANDA IS NOT FORECAST TO REACH THE LONGITUDE OF THE MAIN HAWAIIAN

ISLANDS AS AN INTACT TROPICAL SYSTEM.



FERNANDA REMAINS IN AN UNFAVORABLE ENVIRONMENT, WITH SEA SURFACE