164
FXHW01 KWNH 080801
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
401 AM EDT SUN MAR 8 2026
VALID 00Z MON 09 MAR 2026 - 00Z MON 16 MAR 2026
...PROLONGED AND POTENTIALLY SIGNIFICANT FLASH FLOOD THREAT
DEVELOPING THIS WEEK...
A MAJOR SYNOPTIC REGIME SHIFT IS UNDERWAY AS THE PREVAILING DRY
AND STABLE EAST-SOUTHEAST TRADE FLOW IS REPLACED BY AN
EXCEPTIONALLY MOIST AND UNSTABLE KONA WIND PATTERN. ALOFT, GLOBAL
MODELS AND THEIR RESPECTIVE ENSEMBLES ARE IN HIGH AGREEMENT
REGARDING THE AMPLIFICATION OF A DEEP UPPER-LEVEL TROUGH NORTHWEST
OF THE ISLANDS. THIS FEATURE IS EXPECTED TO ACQUIRE A NEGATIVE
TILT AS A POWERFUL 120-140 KT JET STREAK AT 250 MB DIGS ALONG ITS
WESTERN PERIPHERY.
GIVEN THE BLOCKY NATURE OF THE UPPER-LEVEL PATTERN, THIS SYSTEM
WILL BE SLOW-MOVING, AGAIN LEADING TO HIGHER THAN NORMAL
CONFIDENCE FOR EARLY MARCH IN A MULTI-DAY HEAVY RAIN EVENT FOR
HAWAII.
BROAD EXIT-REGION UPPER FORCING WILL MAINTAIN A DIFLUENT UPPER
FLOW PATTERN FOR SEVERAL DAYS, WHILE ALSO TAPPING TROPICAL
MOISTURE NORTHWARD ACROSS THE ISLANDS. PWATS ARE EXPECTED TO
RANGE GENERALLY BETWEEN 1.8-2.0 INCHES TUESDAY THROUGH THURSDAY.
HOWEVER, A MORE IMPRESSIVE DEEP-LAYER MOISTURE PLUME IS
ANTICIPATED FRIDAY THROUGH THE WEEKEND, WHEN PWATS SPIKE BETWEEN
2.0-2.3" ACROSS THE ENTIRE STATE. DURING THIS TIME, INTEGRATED
WATER VAPOR TRANSPORT VALUES OR IVTS ARE EXPECTED TO PERSIST OVER
700 KG/M-S PER THE LATEST GFS AND ECMWF. CERTAINLY ALL OF THE
INGREDIENTS WILL BE IN PLACE FOR POTENTIALLY SIGNIFICANT FLASH
FLOODING BY MID-LATE WEEK AND THROUGH THE WEEKEND, ESPECIALLY AS
SOILS BECOME SATURATED AND STREAM/RESERVOIR LEVELS RISE ACROSS ALL
ISLANDS.
NEXT WEEKEND WILL BE OF PARTICULAR CONCERN, PARTICULARLY
OVER THE WESTERN AND CENTRAL ISLANDS. THIS WILL BE SEVERAL DAYS
INTO THIS MULTI-DAY EVENT WITH ALREADY SATURATED SOILS AND HIGH
STREAM LEVELS, WHEN PWATS, IVTS, LOW-LEVEL SOUTHWESTERLY FLOW AND
MOISTURE FLUX ANOMALIES WILL BE GREATEST PER THE GUIDANCE.
HURLEY
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