Prognostic Meteorological Discussion
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FXHW01 KWNH 171218
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
817 AM EDT THU AUG 17 2017

VALID 00Z FRI AUG 18 2017 - 00Z FRI AUG 25 2017

A STRONG SPRAWLING AREA OF SURFACE HIGH PRESSURE NORTH AND
NORTHEAST OF HAWAII SHOULD KEEP TRADITIONAL EASTERLY TRADES AND
WINDWARD SHOWERS IN EFFECT FOR THE MAJORITY OF THE FORECAST
PERIOD. THE OPERATIONAL GFS AND ECMWF DO INDICATE A PRONOUNCED
UPPER-LEVEL WEAKNESS AND INVERTED TROUGH TRACKING EAST ACROSS THE
STATE BUT THIS SHOULD NOT IMPACT THE SENSIBLE WEATHER MUCH, IF AT
ALL.

LATE THIS WEEKEND INTO EARLY TO MID NEXT WEEK, MOISTURE CONTENT
WILL BE ON THE INCREASE AND BECOME ANOMALOUS (PRECIPITABLE WATER
VALUES REACH 2.5 TIMES ABOVE AVERAGE). OPERATIONAL AND ENSEMBLE
GUIDANCE INDICATE A POSSIBLE TROPICAL DISTURBANCE AND INFLUX OF
MOISTURE ALONG THE ITCZ (INTER TROPICAL CONVERGENCE ZONE) TO
ADVECT IN FROM THE EAST AND SOUTHEAST, WHILE AN EXPOSED
CIRCULATION NEAR 18N134W MOVES THROUGH THE CHAIN AS AN EASTERLY
WAVE. THE CENTRAL PACIFIC HURRICANE CENTER GIVES THIS FEATURE AN
80 PERCENT PROBABILITY TO DEVELOP OVER THE NEXT 5 DAYS. THE
GUIDANCE HAS DEFINITELY BACKED OFF SINCE YESTERDAY ON THE
NORTHWARD LATITUDE OF THE AREA OF DISTURBED WEATHER AND THERE ALSO
REMAINS NOT A TON OF MODEL SUPPORT FOR A TRUE AREA OF LOW PRESSURE
TO REACH THE ISLANDS. THE BOTTOM LINE APPEARS THAT A SURGE OF
MOISTURE WILL PASS THROUGH THE ISLANDS AND PERHAPS THE LARGEST
IMPACT WILL BE SOME MORE ORGANIZED AND PERSISTENT SHOWER ACTIVITY
ALONG WITH WAVE ACTION.

MUSHER


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