425
FXHW01 KWNH 250851
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
351 AM EST THU DEC 25 2025
VALID 00Z FRI 26 DEC 2025 - 00Z FRI 02 JAN 2026
AN UPPER-LEVEL RIDGE CENTERED OVER THE ISLANDS WILL MAINTAIN
STABLE CONDITIONS AT THE START OF THE PERIOD, WHILE A ROBUST
SURFACE HIGH TO THE NORTH CONTINUES TO DRIVE THE SYNOPTIC PATTERN.
SIMULTANEOUSLY, THE SURFACE HIGH WILL MIGRATE EAST, ALLOWING THE
PRESSURE GRADIENT TO RELAX AND SURFACE WINDS TO VEER TO A MORE
SOUTHEASTERLY DIRECTION. THIS WILL INTRODUCE A RELATIVELY DRIER
AIRMASS FROM THE EAST THAT WILL REMAIN IN PLACE INTO THE WEEKEND.
THE PATTERN IS EXPECTED TO TRANSITION LATE IN THE WEEKEND AS THE
UPPER RIDGE SHIFTS EASTWARD, AND BY MONDAY, AN UPPER-LEVEL TROUGH
IS FORECAST TO MOVE ACROSS THE CENTRAL PACIFIC NORTH OF THE STATE.
THIS FEATURE WILL PUSH A COLD FRONT TOWARD THE WESTERN ISLANDS.
WHILE MODEL GUIDANCE REMAINS UNCERTAIN REGARDING THE PRECISE
TIMING OF THIS BOUNDARY, THE GENERAL CONSENSUS FAVORS THE FRONT
STALLING AND WEAKENING IN THE VICINITY OF THE WESTERN ISLANDS
DURING THE FIRST HALF OF THE WEEK. AHEAD OF THIS FEATURE, THE
GLOBAL GUIDANCE SHOWS AN UPTICK IN PWATS, LIKELY APPROACHING OR
EXCEEDING 1.5+ INCHES, AS ML CAPES LIKELY REACH 250-500+ J/KG.
THIS WILL BRING AN INCREASED RISK FOR SHOWERS DURING THE EARLY
PART OF NEXT WEEK, PARTICULARLY OVER MORE ELEVATED WINDWARD
SLOPES, FOLLOWED BY A RETURN TO MORE STANDARD NORTHEASTERLY TRADES
AS HIGH PRESSURE AND A DRIER REGIME BUILD BACK ACROSS THE ISLANDS
TO START OFF THE NEW YEAR.
HURLEY
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