Prognostic Meteorological Discussion
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FXHW01 KWNH 191202
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
702 AM EST SUN NOV 19 2017

VALID 00Z MON NOV 20 2017 - 00Z MON NOV 27 2017

GUIDANCE IS AGREEABLE AND CONSISTENT IN DEPICTING A PERSISTENT
MEAN TROUGH ALOFT ORIENTED NORTHEAST-SOUTHWEST OVER THE STATE.
UNDER THE CYCLONIC FLOW PRECIPITABLE WATER VALUES ARE FORECAST TO
BE BELOW NORMAL THROUGH THE PERIOD BUT WITH SOME DIFFERENCES,
NAMELY THE ECMWF BEING SOMEWHAT DRIER THAN 00Z/06Z GFS RUNS.  THE
RELATIVELY LOW MOISTURE LEVELS SHOULD KEEP MOST SHOWER ACTIVITY
(WINDWARD FOCUSED BUT OCCASIONALLY STRAYING TO LEEWARD LOCATIONS)
FAIRLY LIGHT.  HOWEVER THE UPPER TROUGHING WITH MULTIPLE EMBEDDED
SHORTWAVE IMPULSES MAY HELP TO OPTIMIZE WHAT RAINFALL COULD OCCUR
GIVEN AVAILABLE MOISTURE.

DEEPEST UPPER TROUGHING/SURFACE LOW PRESSURE INITIALLY TO THE
NORTHEAST OF THE STATE WILL LIFT AWAY DURING THE FIRST PART OF THE
WEEK.  AS THIS OCCURS AND CENTRAL PACIFIC HIGH PRESSURE BUILDS
SOUTHEASTWARD, EXPECT NORTHWESTERLY/NORTHERLY LOW LEVEL WINDS TO
BECOME MORE NORTHEASTERLY BY MIDWEEK AND THEN EVENTUALLY
EAST-NORTHEASTERLY.  THERE IS REASONABLE CONSENSUS THAT HIGH
PRESSURE SHOULD REACH A POSITION NORTH OF THE ISLANDS BETWEEN
30-40N LATITUDE BY NEXT SUNDAY.  A FAIRLY TIGHT PRESSURE GRADIENT
WILL PROMOTE BRISK/WINDY TRADES FROM LATE WEEK THROUGH THE WEEKEND.

RAUSCH

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