664
FXHW01 KWNH 220740
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
340 AM EDT SUN MAR 22 2026
VALID 00Z MON 23 MAR 2026 - 00Z MON 30 MAR 2026
..FLASH FLOOD THREAT TO CONTINUE INTO MONDAY ACROSS HAWAI'I
THE PATTERN ALOFT MEANS TROUGHY OVER THE ARCHIPELAGO DURING THE NEXT
WEEK, WITH MID-LEVEL RIDGING MAKING SOME STRIDES TOWARDS
LONGER TERM REBUILDING OVER THE PAPAHANAUMOKUAKEA MARINE NATIONAL
MONUMENT LATE IN THE WEEK.
INITIALLY, A DEEP LAYER CYCLONE TO THE NORTH IS WORKING IN TANDEM
WITH LOW LEVEL RIDGING EAST OF HAWAI'I TO MAINTAIN AN ATYPICAL
SOUTHWEST FLOW REGIME INTO MONDAY. ABOVE AVERAGE PRECIPITABLE
WATER VALUES ARE PLACED FAVORABLY BENEATH DIFFLUENT UPPER LEVEL
WINDS. COMBINED WITH FAVORABLE UPSLOPE ASCENT INTO SOUTHWEST-
FACING TERRAIN, EXCESSIVE RAINFALL RATES WILL REMAIN IN THE
FORECAST INTO MONDAY AS THE CYCLONE'S FRONT EDGES EASTWARD
THROUGH THE MAIN ISLANDS AND THE LOW PRESSURE SYSTEM LIFTS
NORTHEAST. WITH SOILS SATURATED AND FLOODING ONGOING, HAWAII
REMAINS VULNERABLE TO ADDITIONAL LIFE- THREATENING FLASH FLOODING
AND LANDSLIDES.
AS SURFACE RIDGING BEGINS TO BUILD IN LATE MONDAY ONWARD TO THE
NORTH AND NORTHEAST, THE ANOMALOUS MOISTURE PLUME WILL
WEAKEN/SHIFT AWAY. THIS IS WILL DECREASE RAINFALL AMOUNTS AND
RAIN CHANCES THROUGH THE REMAINDER OF THE WEEK AND RETURN HAWAI'I
TO THEIR MORE TYPICAL TRADE WIND/UPSLOPE SHOWER REGIME.
ROTH
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