115
FXHW01 KWNH 220753
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
352 AM EDT WED MAR 22 2023
VALID 00Z THU MAR 23 2023 - 00Z THU MAR 30 2023
GUIDANCE IS SHOWING A PATTERN FAVORING CENTRAL PACIFIC UPPER LOWS
THAT WILL LEAD TO PERIODS OF SOMEWHAT ENHANCED SHOWERS WITH
SOUTHEASTERLY BACKGROUND FLOW, AND MORE TYPICAL TRADES AND
WINDWARD FOCUSED RAINFALL IN BETWEEN. CONSENSUS DEPICTS THE
LEADING UPPER LOW NORTHWEST OF THE ISLANDS PASSING BY TO THE NORTH
MID-LATE WEEK, HELPING TO PUSH A SURFACE TROUGH AND MOISTURE AXIS
INTO THE WESTERN-CENTRAL ISLANDS. THIS MOISTURE SHOULD LEAD TO
HIGHER RAINFALL TOTALS MAINLY DURING WEDNESDAY-THURSDAY, THOUGH
MODELS STILL DIFFER A BIT ON RAINFALL TOTALS. THE SOUTHEASTERLY
BACKGROUND FLOW MAY BE LIGHT ENOUGH TO ALLOW FOR SEA/LAND BREEZE
INFLUENCE ON SHOWERS OVER SOME AREAS. THEN DEPARTURE OF THE UPPER
LOW WILL PROMOTE A RETURN OF TYPICAL TRADE FLOW STARTING BY FRIDAY
OR SATURDAY AND CONTINUING INTO EARLY NEXT WEEK. DURING THIS TIME
FRAME, ANOTHER UPPER LOW NORTHWEST OF THE STATE SHOULD STAY JUST
FAR ENOUGH AWAY NOT TO HAVE TOO MUCH INFLUENCE ON THE PATTERN OVER
THE MAIN ISLANDS. HOWEVER FROM MONDAY ONWARD UPSTREAM ENERGY WILL
DISPLACE THAT LOW AND ULTIMATELY LEAD TO A MORE AMPLIFIED UPPER
TROUGH WITH YET ANOTHER EMBEDDED LOW. MOST GUIDANCE SAYS THAT
THIS UPPER TROUGH WILL REACH CLOSE ENOUGH TO SUPPORT A LIGHTER AND
SOUTHEASTERLY TREND FOR WINDS AFTER EARLY MONDAY, AND PUSH A
SURFACE TROUGH TOWARD OR INTO THE WESTERN ISLANDS BY THE MIDDLE OF
NEXT WEEK ALONG WITH SOME INCREASE OF MOISTURE/RAINFALL.
MODELS/MEANS DISPLAY TYPICAL SPREAD FOR FORECASTS 6-7 DAYS OUT IN
TIME, OR EVEN SLIGHTLY BETTER THAN AVERAGE RELATIVE TO WHAT MIGHT
BE EXPECTED FOR THE PATTERN. THUS AN AVERAGE OF LATEST GUIDANCE
WOULD BE A REASONABLE STARTING POINT FOR THAT PART OF THE FORECAST.
RAUSCH
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