523
FXHW01 KWNH 230845
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
345 AM EST MON FEB 23 2026
VALID 00Z TUE 24 FEB 2026 - 00Z TUE 03 MAR 2026
THE SYNOPTIC PATTERN CURRENTLY FEATURES A SHORTWAVE TROUGH NEAR
THE ISLANDS, WHICH IS FORECAST TO SHEAR EASTWARD AS STRONGER
UPPER-LEVEL HEIGHT FALLS EVOLVE WELL TO THE NORTH BETWEEN 30N TO
40N. IN ITS WAKE, SURFACE RIDGING WILL ADVANCE SOUTHWARD IN BEHIND
A WEAK COLD FRONT. THIS BOUNDARY IS EXPECTED TO QUICKLY LOSE ITS
IDENTITY AND WASH OUT THROUGH TUESDAY AND WEDNESDAY. HOWEVER,
LINGERING MOISTURE NEAR THE DISSIPATING FRONT, COMBINED WITH AN
EAST-TO-NORTHEAST FLOW INTO THE WINDWARD SLOPES, WILL CONTINUE TO
FOSTER AREAS OF LOCALLY HEAVY SHOWERS. THE HIGHEST POTENTIAL FOR
ADDITIONAL HEAVY RAIN THROUGH MIDWEEK WILL FOCUS ON MAUI AND THE
BIG ISLAND, WHERE FAVORABLE UPSLOPE FLOW MAY LEAD TO SHOWERS AND
ISOLATED THUNDERSTORMS BECOMING ANCHORED TO THE TERRAIN. AN
ISOLATED FLASH FLOOD CONCERN CANNOT BE ENTIRELY RULED OUT DURING
THIS TRANSITION.
BY THE LATTER HALF OF THE WEEK, THE ARRIVAL OF A FLAT SHORTWAVE
RIDGE WILL PROMOTE A DRIER AND MORE STABLE REGIME. DURING THIS
WINDOW, MODEST EAST-TO-NORTHEAST TRADE WINDS WILL PREVAIL, WITH
PRECIPITATION LIMITED TO ISOLATED SHOWERS FOCUSED PRIMARILY ALONG
WINDWARD SLOPES. MODEL AGREEMENT IS HIGH FOR THIS PERIOD,
REFLECTING A RETURN TO A MORE STANDARD WIND DISTRIBUTION.
UNCERTAINTY INCREASES HEADING INTO NEXT WEEKEND AS AN UPPER-LEVEL
TROUGH TO THE NORTHWEST OF THE STATE BEGINS TO APPROACH, DRIVING A
WEAK COLD FRONT EASTWARD. THIS FEATURE WILL LIKELY SLACKEN THE
TRADE WIND GRADIENT WHILE DRAWING A SURGE OF NEW MOISTURE TOWARD
THE WESTERN END OF THE ISLAND CHAIN. WHILE THE DETERMINISTIC
ECMWF, GFS, AND CMC REMAIN SLOWER AND DRIER, THE EC-AIFS AND
AIGFS SOLUTIONS ARE MORE PROGRESSIVE. GIVEN THAT ENSEMBLE MEANS
CURRENTLY FAVOR THE MORE PROGRESSIVE AI GUIDANCE, THE FORECAST
LEANS TOWARD THAT CONSENSUS. THIS WILL RESULT IN AN INCREASED
THREAT OF SHOWERS FOR THE WESTERN ISLANDS, PARTICULARLY KAUAI AND
OAHU, BY NEXT SUNDAY.
ORRISON
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