006
FXHW01 KWNH 210744
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
344 AM EDT TUE APR 21 2026
VALID 00Z WED 22 APR 2026 - 00Z WED 29 APR 2026
A WEAK LOW PRESSURE SYSTEM NORTH OF THE ISLANDS WILL INITIALLY
MAINTAIN A LIGHT, SOMEWHAT VEERED EAST-SOUTHEASTERLY FLOW REGIME,
ALLOWING DIURNAL LAND AND SEA BREEZES TO DICTATE SENSIBLE WEATHER.
BY LATE IN THE WEEK AND INTO THE WEEKEND, SURFACE HIGH PRESSURE
STRENGTHENING WELL NORTH OF THE REGION WILL USHER A RETURN TO A
MORE STABLE, MODERATE TRADE WIND PATTERN WHICH WILL LAST THROUGH
THE REMAINDER OF THE FORECAST PERIOD. BY LATE IN THE WEEK, ALL
GLOBAL SUITES (GFS/ECMWF/CMC) AND THEIR ENSEMBLES ARE IN EXCELLENT
ALIGNMENT WITH RESPECT TO THE STRENGTHENING MID-LEVEL SUBTROPICAL
RIDGE OVER THE ISLANDS.
IN THE SHORT TERM, LIGHT EAST-SOUTHEAST SYNOPTIC FLOW WILL PERSIST
THROUGH WEDNESDAY. PWAT VALUES WILL HOVER ~ 1.3 TO 1.5 INCHES
EARLY ON, PROVIDING SUFFICIENT MOISTURE FOR DIURNAL CONVECTIVE
ACTIVITY. GIVEN THE RELAXED PRESSURE GRADIENT, DIURNAL HEATING
WILL FOSTER AFTERNOON SEA BREEZES, FOCUSING SCATTERED SHOWERS OVER
INLAND INTERIORS.
BY THE END OF THE WEEK INTO EARLY NEXT WEEK, A DRYING AND
STABILIZING TREND WILL ENSUE AS UPPER-LEVEL RIDGING BUILDS (SUBSIDENCE
INVERSION STRENGTHENS/LOWERS TO 5-7KFT). HIGH PRESSURE CENTERED
WELL NORTH WILL ALLOW FOR A RETURN OF MODERATE NORTHEASTERLY TRADE
WINDS, PERSISTING THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK.
PWATS TOO WILL BE ON THE DOWNWARD TREND, STABILIZING CLOSER TO
CLIMO FOR LATE APRIL (1.1 TO 1.3 INCHES). CONSEQUENTLY, POPS
DURING THIS PERIOD WILL DROP OVER INTERIOR REGIONS, AS THE
PRECIPITATION REGIME TRANSITIONS BACK TO A CLASSIC TRADE-WIND
DISTRIBUTION.
HURLEY
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