229
FXHW01 KWNH 190859
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
459 AM EDT WED AUG 19 2026
VALID 00Z THU 20 AUG 2026 - 00Z THU 27 AUG 2026
A TRADE WIND PATTERN IS GENERALLY EXPECTED OVER THE NEXT SEVERAL
DAYS, WITH THE TYPICAL WINDWARD SHOWER ACTIVITY. A WEAK WAVE OF
LOW PRESSURE MOVING NORTH OF THE ISLANDS BY THURSDAY INTO FRIDAY
SHOULD DISRUPT THE TRADES AND SLIGHTLY INCREASE INSTABILITY OVER
THE AREA. STILL LOOKING AT SCATTERED SHOWER ACTIVITY, BUT MAY BE
MORE SEA BREEZE AND TERRAIN INDUCED COMPARED TO THE TYPICAL
WINDWARD TRADE SHOWERS.
IT IS INCREASINGLY LIKELY THAT A TROPICAL CYCLONE WILL FORM TO
THE SOUTHEAST OF THE ISLANDS LATER THIS WEEK AND TRACK WEST-
NORTHWEST INTO THIS WEEKEND. A MAJORITY OF THE 00Z ECMWF, GFS AND
GOOGLE DEEPMIND ENSEMBLE MEMBERS KEEP THE SYSTEM SOUTH OF THE
ISLANDS THIS WEEKEND, ALTHOUGH SOME NORTHWARD TREND IS NOTED. AT A
MINIMUM SOME INCREASE IN MOISTURE WILL ENHANCE TRADE SHOWERS AS
IT PASSES TO THE SOUTH. HOWEVER, THE THREAT OF GREATER IMPACTS IS
GROWING, ESPECIALLY ON THE BIG ISLAND WHERE MORE SIGNIFICANT
RAINFALL AND FLASH FLOODING IS A POSSIBILITY OVER THE WEEKEND. WE
WILL NEED TO CLOSELY MONITOR TRENDS OVER THE COMING DAYS.
CHENARD
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