021
FXHW01 KWNH 220840
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
340 AM EST SUN FEB 22 2026
VALID 00Z MON 23 FEB 2026 - 00Z MON 02 MAR 2026
THE SYNOPTIC PATTERN AT THE START OF THE PERIOD WILL BE
CHARACTERIZED BY AN UPPER-LEVEL TROUGH GRADUALLY WEAKENING AND
PULLING AWAY TO THE NORTHEAST. HOWEVER, A SURFACE COLD FRONT
CURRENTLY JUST NORTH OF THE ISLANDS WILL BE SLOWLY DROPPING
SOUTHWARD AND SHOULD MOVE THROUGH THE ISLANDS THROUGH MONDAY. THE
SLOW PROGRESSION OF THIS BOUNDARY, COUPLED WITH MOIST EAST-TO-
NORTHEAST FLOW, WILL FAVOR AREAS OF LOCALLY HEAVY SHOWERS AND
THUNDERSTORMS ALONG WINDWARD SLOPES. CLIMATOLOGICALLY FAVORED
WINDWARD AND MAUKA AREAS OF KAUAI, OAHU, MOLOKAI, AND MAUI APPEAR
MOST AT RISK FOR THE HEAVIEST RAINFALL, WITH AT LEAST A FEW INCHES
OF RAIN EXPECTED LOCALLY WHERE THE HEAVIER SHOWERS BECOME
ANCHORED TO THE TERRAIN. THE 00Z HREF GUIDANCE SUPPORTS THIS
SCENARIO. CONSEQUENTLY, LOCALIZED FLASH FLOODING CONCERNS WILL
REMAIN ELEVATED THROUGH THE EARLY PART OF THE WEEK.
ON TUESDAY AND WEDNESDAY, THERE MAY BE SOME ADDITIONAL SHOWERS
FOCUSED OVER THE BIG ISLAND AS NEARBY REMNANTS OF THE FRONT AND
MOISTURE ALONG IT REMAINS FOCUSED NEARBY. HOWEVER, THIS BOUNDARY
IS FORECAST TO WEAKEN AND LOSE ITS IDENTITY AS SURFACE HIGH
PRESSURE BUILDS DOWN FROM THE NORTH AND BECOMES THE DOMINANT
FEATURE. WITH A DEEPER-LAYER TROUGH SITUATED WELL TO THE NORTHEAST
AND A NEW UPPER-LEVEL TROUGH DEVELOPING FAR TO THE NORTHWEST, THE
ISLANDS WILL TRANSITION INTO A DRIER, MORE STABLE REGIME FOR THE
LATTER HALF OF THE WEEK. PRECIPITATION SHOULD GRADUALLY BECOME
LIMITED TO SPARSE WINDWARD SHOWERS EMBEDDED IN TYPICAL EAST-TO-
NORTHEAST TRADE WINDS. THE 00Z GUIDANCE SHOWS VERY GOOD MODEL
AGREEMENT, WITH THE EC-AIFS AND AIGFS SOLUTIONS ALIGNED WITH THE
GFS, ECMWF, AND CMC RUNS.
CONFIDENCE DECREASES SLIGHTLY TOWARD THE END OF THE WEEK (DAYS
5-7) AS THE TROUGH TO THE NORTHWEST SHIFTS EASTWARD, DRIVING A
WEAK COLD FRONT TOWARD THE STATE FROM THE WEST. THIS FEATURE WILL
LIKELY SLACKEN THE TRADE WIND GRADIENT WHILE INCREASING MOISTURE
ACROSS KAUAI AND OAHU. WHILE THE REMAINING DETERMINISTIC CONSENSUS
IS SLOWER, THE ECMWF, EC-AIFS AND AIGFS ARE MORE PROGRESSIVE IN
BRINGING A RETURN OF HEAVY SHOWER ACTIVITY TO THE WESTERN ISLANDS
NEXT WEEKEND.
ORRISON
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