761
FXHW01 KWNH 280747
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 AM EST SUN DEC 28 2025
VALID 00Z MON 29 DEC 2025 - 00Z MON 05 JAN 2026
THE PATTERN ACROSS HAWAII CONTINUES TO TRANSITION FROM A STABLE,
HIGH-PRESSURE DOMINATED REGIME TO A MORE COMPLEX SETUP AS THE
UPPER-LEVEL RIDGE CONTINUES TO SHIFT EASTWARD WHILE A SURFACE FRONT
STALLS JUST WEST-NORTHWEST OF THE WESTERN ISLANDS. LOW-LEVEL WINDS
WILL CONTINUE TO VEER SOUTHEASTERLY AS THE MORE TYPICAL NORTHEAST-
EASTERLY TRADES HAVE SHIFTED EAST.
ALOFT, A WEAKENING UPPER-LEVEL TROUGH WILL SLIDE NORTH OF THE
ISLANDS ON SUNDAY, WHILE A MORE DISTINCT MID-TO-UPPER LEVEL
SHORTWAVE WILL APPROACH FROM THE NORTHWEST BY MONDAY AND TUESDAY.
THE LOWER HEIGHTS AND WEAKENING MID-LEVEL CAP WILL ALLOW FOR SOME
UPTICK IN INSTABILITY, PARTICULARLY OVER THE WESTERN ISLANDS
(KAUAI AND OAHU), WHICH ALONG WITH THE DEEPER MOISTURE (PWATS NEAR
1.5"), WILL LEAD TO INCREASED CHANCES/COVERAGE OF DIURNAL SHOWERS
THROUGH TUESDAY. MEANWHILE, THE EASTERN ISLANDS (MAUI AND BIG
ISLAND) WILL REMAIN UNDER A MORE STABLE AIRMASS, AS DIURNAL
SHOWERS WILL BE LIGHTER AND MORE ISOLATED, PRIMARILY FOCUSED OVER
THE WINDWARD SLOPES AND INTERIOR MAUKA AREAS DURING THE AFTERNOON
PEAK HEATING HOURS.
BY MID-WEEK INTO THE NEW YEAR, THE GLOBAL MODELS ARE IN FAIRLY
GOOD AGREEMENT WITH THE RETURN OF DEEP-LAYER RIDGING (SURFACE HIGH
REBUILDING NORTH OF THE ISLANDS), WHICH WILL HERALD THE RETURN OF
MORE TYPICAL MODERATE TO BREEZY EASTERLY TRADES THROUGHOUT THE
HAWAIIAN ARCHIPELAGO. THIS REGIME WILL LIKELY PERSIST THROUGH THE
FIRST WEEKEND OF THE NEW YEAR, AS THE DIURNAL SHOWER CHANCES
BECOME CONFINED TO THE TRADITIONAL WINDWARD AND MAUKA AREAS.
HURLEY
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