Heavy Rain in Hawaii, September 1 to 2, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST MON SEP 1 2014

.SYNOPSIS...
A LIGHT EAST-SOUTHEAST WIND FLOW IS EXPECTED TO CONTINUE TODAY AS A
SURFACE TROUGH STAYS FAR NORTHWEST OF THE STATE. THE LIGHT WINDS
WILL ALLOW AFTERNOON SEA BREEZES TO DEVELOP...BRINGING LOCALIZED
CLOUD BUILDUPS WITH POSSIBLY A FEW SHOWERS MAINLY OVER LEEWARD AND
INTERIOR AREAS. SLIGHTLY STRONGER TRADES ARE EXPECTED TO BUILD IN
LATER THIS WEEK AS A HIGH PRESSURE RIDGE BUILDS NORTH OF THE
ISLANDS. WITH THE STRENGTHENING TRADES...EXPECT THE CLOUDS AND
SHOWERS TO BE FOCUSED MORE OVER THE WINDWARD SLOPES.

&&

.DISCUSSION...
ONCE AGAIN...RATHER FAIR WEATHER PREVAILS OVER THE STATE THIS
MORNING AS LIGHT WINDS PERSIST WITH LAND BREEZES OVER THE ISLANDS. A
SURFACE TROUGH FAR NORTHWEST OF THE STATE IS KEEPING SYNOPTIC WIND
FLOW EAST SOUTHEASTERLY AND LIGHT ACROSS THE ISLANDS TODAY. AS THE
DAY PROGRESSES...SEA BREEZES WILL DEVELOP...RESULTING IN LOCALIZED
CLOUDS FORMING OVER THE LEE AND INTERIOR SECTIONS OF THE ISLANDS.
AIR MASS IS MARGINALLY UNSTABLE...WITH NEAR NORMAL MOISTURE AS
INDICATED BY EARLY MORNING SOUNDINGS. THEREFORE...DAYTIME CLOUDS MAY
BRING SOME SHOWERS TO THE AFOREMENTIONED AREAS.

ALTHOUGH THAT SURFACE TROUGH WILL PERSIST FAR NORTHWEST OF THE
ISLANDS THROUGH EARLY THIS WEEK...FORECAST MODELS CONTINUE TO
INDICATE A SURFACE HIGH PRESSURE RIDGE WILL DEVELOP NORTH OF THE
STATE IN THE COMING DAYS. THIS WILL ALLOW STRONGER TRADES TO RETURN
TO THE ISLANDS. AS THIS RIDGE WILL NOT BE TOO STRONG...THE SURFACE
PRESSURE GRADIENT ACROSS THE ISLANDS WILL REMAIN SOMEWHAT SLACK AND
THUS THE BUILDING TRADE WINDS WILL BE MODEST AT MOST.
THEREFORE...MAY SEE A MORE HYBRID TRADE WIND AND CONVECTIVE WEATHER
PATTERN IN THE NEXT FEW DAYS WITH CLOUDS AND SHOWERS EMBEDDED IN THE
TRADE WINDS TO AFFECT WINDWARD AREAS...WHILE AFTERNOON CLOUDS WITH
POSSIBLE A FEW SHOWERS WILL BUILD OVER THE LEE AREAS. THE MODELS
ALSO SHOW LIMITED LOW LEVEL MOISTURE IN THE NEXT COUPLE OF DAYS
ACROSS THE STATE...AND THIS MAY RESULT LIMITED PRECIPITATION FOR THE
ISLANDS AS WELL.

MODEL RUNS CONTINUE TO SHOW HIGHER LOW LEVEL MOISTURE EMBEDDED
IN THE TRADE WIND FLOW REACHING THE ISLANDS TOWARDS THE LATER PART
OF THE WEEK. THIS INCREASED MOISTURE APPEARS TO BE LOOSELY
ASSOCIATED WITH THE REMNANT OF MARIE. THEREFORE...EXPECT AN
UPTICK IN THE SHOWERS UNDER THE LIGHT TO MODERATE TRADE WINDS FOR
THE STATE.

&&

.AVIATION...
LIGHT ESE BACKGROUND FLOW WILL CONTINUE TODAY. SEABREEZES SHOULD
DEVELOP THIS AFTERNOON...BRINGING CLOUDS AND POSSIBLE SHOWERS TO THE
INTERIOR AND LEEWARD AREAS. BRIEF PERIODS OF MVFR MAY OCCUR WITHIN
THESE CLOUDS AND SHOWERS. ANY SEABREEZE INDUCED CONVECTION WILL
DIMINISH WITH SUNSET. ISOLATED MVFR WILL ALSO BE POSSIBLE ACROSS
WINDWARD SECTIONS TONIGHT AS WEAK TRADE WIND FLOW RESUMES.
OTHERWISE...VFR WILL PREVAIL THROUGH THE PERIOD.

&&

.MARINE...
THE CURRENT SOUTH SWELL CONTINUES THIS MORNING...WITH READINGS FROM
NEAR SHORE BUOY JUST SOUTHWEST OF OAHU REMAINED ELEVATED. EXPECT THE
ELEVATED SURF TO PERSIST TODAY...THEN SLOWLY SUBSIDE TONIGHT.

A VERY LONG PERIOD SOUTH SWELL...20-25 SECONDS...IS DUE TO ARRIVE
EARLY TUESDAY...THEN BUILDING THROUGH WEDNESDAY. THIS SWELL WILL
LIKELY PRODUCE ADVISORY LEVEL SURF WEDNESDAY INTO THURSDAY.

WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS FOR
AT LEAST THE NEXT SEVERAL DAYS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

AVIATION...EATON
REST...HUI