940
FXHW01 KWNH 090756
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
355 AM EDT TUE APR 09 2024
VALID 00Z WED APR 10 2024 - 00Z WED APR 17 2024
CONTINUE TO EXPECT WEAKENING TRADES TO TURN SOUTHEASTERLY BY
WEDNESDAY AS A DEEP-LAYER LOW CLOSES OFF NORTHWEST OF THE MAIN
ISLANDS WITH A FRONT/CONVERGENCE AXIS EXTENDING SOUTH FROM THE
SURFACE LOW. THE UPPER LOW SHOULD ACHIEVE ITS MOST SOUTHERN
LATITUDE AROUND EARLY FRIDAY AND THEN LIFT NORTHEASTWARD,
ULTIMATELY BEING REPLACED BY ANOTHER UPPER LOW NEAR 40N. THE
UPPER TROUGH AXIS ANCHORED BY THESE LOWS SHOULD BEGIN TO DRIFT
EASTWARD BY SUNDAY-TUESDAY, PUSHING THE SURFACE FRONT EASTWARD
INTO THE WESTERN AND POSSIBLY CENTRAL MAIN ISLANDS DURING THE
FIRST HALF OF NEXT WEEK. THE OVERALL PATTERN WILL SUPPORT A
NORTHWARD SURGE OF MOISTURE, LIKELY BRINGING PRECIPITABLE WATER
VALUES TO 1.5 INCHES OR HIGHER FOR MULTIPLE DAYS AFTER MIDWEEK.
DYNAMICAL GUIDANCE AND ECMWF-INITIALIZED MACHINE LEARNING MODELS
STILL SUGGEST THAT THE SYSTEM'S TRAILING SURFACE BOUNDARY WILL
FOCUS AN AXIS OF POTENTIALLY HEAVY RAINFALL OVER OR JUST WEST OF
KAUAI AND VICINITY FROM THURSDAY ONWARD. EFFECTS OVER THE WESTERN
ISLANDS CONTINUE TO BE SENSITIVE TO EXACT LONGITUDE OF THE HEAVY
RAIN AXIS, WITH NO CLEAR CLUSTERING/TRENDING YET TO EMERGE WITHIN
THE OVERALL GUIDANCE ENVELOPE. THERE IS REASONABLE AGREEMENT
TOWARD GRADUAL EASTWARD PROGRESSION OF THE SURFACE FEATURE AND
SUPPORTING UPPER TROUGH BY SUNDAY INTO THE EARLY PART OF THE NEXT
WORK WEEK, WHICH WOULD SPREAD RAINFALL OVER MORE OF THE WESTERN
HALF OF THE ISLANDS AND PERHAPS EVENTUALLY BRING SOME DRIER AIR
INTO THE FAR WESTERN ISLANDS. THERE IS TYPICAL SPREAD FOR HOW
MUCH EASTWARD PROGRESS THERE IS, WITH AN INTERMEDIATE SOLUTION
PROVIDING A REASONABLE STARTING POINT.
RAUSCH
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