574
FXHW60 PHFO 072006
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1006 AM HST TUE JUL 7 2020
SYNOPSIS
STRENGTHENING TRADE WINDS WILL PERSIST THROUGH THE WEEKEND.
SHOWERS EMBEDDED WITHIN THE TRADE WIND FLOW WILL BE FOCUSED OVER
THE WINDWARD SIDES OF THE ISLANDS, PRIMARILY DURING THE NIGHTS AND
EARLY MORNING HOURS. ADDITIONAL SHOWERS WILL BE LIKELY OVER THE
LEEWARD SLOPES OF THE BIG ISLAND DURING THE AFTERNOON HOURS.
DISCUSSION
A 1033 MB SURFACE HIGH IS CENTERED 1300 MILES NORTH NORTHEAST OF
HAWAII AND IS DRIVING FRESH TRADE WINDS ACROSS THE STATE. 12Z
SOUNDINGS FROM HILO AND LIHUE SHOW A MIDLEVEL INVERSION OVER THE
AREA BETWEEN 7000 AND 9000 FEET WITH NEAR NORMAL PRECIPITABLE
WATER VALUES AROUND 1.2 INCHES. VISIBLE SATELLITE AND RADAR SHOW
LOW CLOUDS AND SHOWERS CARRYING OVER THE ISLANDS BY THE TRADE
WINDS. SHOWERS ARE FOCUSED OVER WINDWARD AND MAUKA AREAS, OCCASIONALLY
SPILLING ONTO LEEWARD SIDES OF THE SMALLER ISLANDS. RAINFALL
MAXIMUMS WILL OCCUR DURING THE NIGHTS AND EARLY MORNINGS, WITH THE
EXCEPTION OF THE KONA SLOPES OF THE BIG ISLAND (AFTERNOONS).
AN UPPER LEVEL LOW TO THE NORTHEAST OF THE ISLANDS IS EXPECTED TO
LIFT FURTHER AWAY OVER THE NEXT SEVERAL DAYS. SOME MIDLEVEL
RIDGING WILL FILL IN BY WEDNESDAY, WHICH COULD HELP TO SHOWER
ACTIVITY INTO THURSDAY. HEADING INTO THIS WEEKEND, A MID TO UPPER
LEVEL LOW IS FORECAST TO MOVE TOWARDS THE ISLANDS. THIS FEATURE
COULD BRING AN INCREASE IN WINDS TO HALEAKALA AND THE BIG ISLAND
SUMMITS DURING THE END OF THE WEEKEND AND THE BEGINNING PART OF
NEXT WEEK. SHOWERS COULD ALSO INCREASE DEPENDING UPON HOW CLOSE
THE LOW NEARS HAWAII.
AVIATION
HIGH PRESSURE WELL NORTH OF THE STATE WILL GENERATE MODERATE TO
LOCALLY BREEZY TRADE WINDS OVER THE NEXT SEVERAL DAYS. SPEEDS
WILL RAMP UP THROUGH TONIGHT AND WILL LIKELY REQUIRE ISSUANCE OF
AIRMET TANGO FOR LOW-LEVEL TURBULENCE LATER THIS AFTERNOON OR
EVENING.
SCATTERED SHOWERS WILL AFFECT MAINLY THE WINDWARD COASTS AND
SLOPES, THOUGH A FEW SHOWERS MAY BE PUSHED OVER TO LEEWARD AREAS
AT TIMES. PERIODS OF MVFR CONDITIONS ARE EXPECTED DUE TO LOWERED
CEILINGS AND DECREASED VISIBILITY IN THE SHOWERS, THOUGH NOT
WIDESPREAD ENOUGH FOR EXTENSIVE MOUNTAIN OBSCURATION.
MARINE
FRESH TO STRONG TRADE WINDS WILL PREVAIL THROUGH THE WEEK AS
STRONG HIGH PRESSURE HOLDS FAR NORTH AND NORTHEAST OF THE
ISLANDS. A SMALL CRAFT ADVISORY (SCA) IS IN EFFECT FOR THE
TYPICALLY WINDIER WATERS AROUND MAUI COUNTY AND THE BIG ISLAND
THROUGH TOMORROW, AND WILL ALMOST CERTAINLY NEED TO BE EXTENDED
THROUGH THE WEEK.
NO SIGNIFICANT SWELLS ARE DUE THROUGH MUCH OF THE WEEK. A MIX OF
MAINLY BACKGROUND SWELLS FROM THE SOUTHWEST AND SOUTHEAST WILL
DOMINATE, WITH A SOUTH-SOUTHWEST SWELL POTENTIALLY BOOSTING SOUTH
SHORE SURF TO AROUND SUMMERTIME AVERAGE ON THURSDAY AND FRIDAY.
TRADE WIND SWELL WILL GRADUALLY BUILD TO AROUND SUMMERTIME AVERAGE
BY THURSDAY OR FRIDAY, THEN HOLD INTO EARLY NEXT WEEK. SURF ALONG
NORTH FACING SHORES WILL REMAIN SMALL.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST WEDNESDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...FOSTER
AVIATION...TS
MARINE...WROE
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