384
FXHW01 KWNH 160756
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
356 AM EDT FRI OCT 16 2026
VALID 00Z SAT 17 OCT 2026 - 00Z SAT 24 OCT 2026
THE GUIDANCE AGREES ON BRISK TRADE WINDS AS SURFACE HIGH PRESSURE
BUILDS TO THE NORTH OF THE ISLANDS IN A REGION OF CONFLUENCE
ALOFT ON THE BACK SIDE OF AN UPPER LEVEL TROUGH. THE ANTICYCLONE
BECOMES INCREASINGLY WARM CORE THROUGH MONDAY AS MID- LEVEL
RIDGING BUILDS NORTH OF HAWAI'I. MEANWHILE, DIRECTLY OVER HAWAI'I,
A STRONGLY POSITIVELY TILTED UPPER TROUGH REMAINS ACROSS THE
STATE, WITH THE GUIDANCE GENERALLY AGREEING ON A MID-LEVEL LOW
FORMING MIDWEEK OVER THE MAIN ISLANDS. LATE NEXT WEEK, THE 00Z
CANADIAN IS ON ITS OWN WITH FORMING A NEW COLD LOW WHICH DROPS
TOWARDS THE NORTHWESTERN HAWAIIAN ISLANDS, WHICH IS NOT SEEN NOR
SUPPORTED BY THE OTHER GLOBAL OR ENSEMBLE MEAN GUIDANCE, SO
BELIEVE IT'S A LOW PROBABILITY ALTERNATIVE SCENARIO, AT BEST.
STRONGER THAN AVERAGE TRADES ARE THEN EXPECTED TO PERSIST THROUGH
THE UPCOMING WEEKEND THROUGH EARLY NEXT WEEK, BEFORE WEAKENING
MID NEXT WEEK AS WEAK UPPER LEVEL TROUGHING STRENGTHENS OVER THE
REGION. ON FRIDAY/SATURDAY AND THEN AGAIN ON SUNDAY/MONDAY AND
LATE NEXT WEEK, DISTURBANCES IN THE EASTERLIES BRING ENHANCED
MOISTURE (PRECIPITABLE WATER VALUES OF 1.5"+) WHICH SHOULD LEAD TO
A RAINFALL UPTICK IN THE MAUKA SHOWER REGIME DURING THOSE
PERIODS. THE MOST IMPRESSIVE OF THE SURGES IS IN A WEEK, WHICH
WILL NEED TO BE WATCHED AS THE UPPER LOW NEAR HAWAI'I DRIFTS
NORTHEAST, LURING THE ITCZ/MONSOON TROUGH NORTHWARD TOWARDS THE
STATE. PRECIPITABLE WATER VALUES COULD RISE TO 2" WHICH WOULD
INCREASE THE RISK OF EXCESSIVE RAINFALL/FLASH FLOODING.
ROTH
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