Prognostic Meteorological Discussion
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FXHW01 KWNH 191230
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
729 AM EST FRI JAN 19 2018

VALID 00Z SAT JAN 20 2018 - 00Z SAT JAN 27 2018

GUIDANCE AGREES THAT BRISK ISLAND TRADES BEGIN TO WEAKEN TODAY AS
A STRONG SURFACE HIGH MOVES NORTHEAST OF THE STATE. THE PATTERN
REMAINS MAINLY DRY UNDER AN UPPER RIDGE. WEAK SHORTWAVE TROUGH AND
HEIGHT FALL APPROACH FROM THE WEST WEAKENS THIS RIDGE OVER THE
WEEKEND INTO EARLY NEXT WEEK. TRADE FLOW DECREASES TO MODERATE
LEVELS AND SOME SCATTERED SHOWERS RETURN STATEWIDE THIS PERIOD.

GUIDANCE CONTINUES TO OFFER MORE VARIANCE AND UNCERTAINTY AT
LONGER TIME FRAMES, BUT GENERALLY AGREES TO PROGRESS AN AMPLIFIED
MID-UPPER LEVEL TROUGH AND A DEEP SURFACE LOW TO THE NORTHWEST OF
THE STATE IN THE WEDNESDAY-NEXT FRIDAY TIMEFRAME. A FAVORED
COMPOSITE OF BEST CLUSTERED GUIDANCE FROM THE 06 UTC GFS/GEFS MEAN
AND 00 UTC ECMWF/ECMWF ENSEMBLE MEAN OFFERS POTENTIAL FOR A
PRECIPITATION FOCUSING TRAILING COLD FRONT TO APPROACH THE WESTERN
ISLANDS AS VEERING LEAD TRADES RETURN MOISTURE OVER THE STATE.

SCHICHTEL

$$





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