Drought in Hawaii, March 15 to 31, 2016

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST MON MAR 14 2016

.SYNOPSIS...
EASTERLY TRADE WINDS WILL GRADUALLY SHIFT OUT OF THE SOUTHEAST
THIS EVENING...THEN BECOME VARIABLE LATE TONIGHT AND TUESDAY
AHEAD OF AN APPROACHING FRONT. CLOUDS AND RAINFALL WILL CONTINUE
TO FAVOR WINDWARD SLOPES THROUGH MUCH OF TONIGHT...FOLLOWED BY A
LAND AND SEA BREEZE REGIME ON TUESDAY. MINIMAL RAINFALL IS
EXPECTED ALONG THE FRONT AS IT MOVES THROUGH THE STATE TUESDAY
NIGHT INTO WEDNESDAY. ANOTHER ROUND OF COOL AND BREEZY NORTHERLY
WINDS WILL DEVELOP BEHIND THE FRONT ON WEDNESDAY AND THURSDAY...
FOLLOWED BY TYPICAL TRADE WIND CONDITIONS DURING THE WEEKEND.

&&

.DISCUSSION...
SHOWERS HAVE BEEN PERSISTENT THIS EVENING ALONG THE WINDWARD
COAST AND KOOLAU RANGE ON OAHU...ACROSS WINDWARD PORTIONS OF
KAUAI...AND ALONG THE SOUTHEAST COAST OF THE BIG ISLAND...WHILE
MOSTLY DRY CONDITIONS PREVAIL ELSEWHERE ACROSS THE STATE. SURFACE
ANALYSIS DEPICTS HIGH PRESSURE FAR NORTHEAST OF THE STATE...WITH A
COLD FRONT NEAR MIDWAY ATOLL OR ABOUT 1100 MILES WNW OF KAUAI. THE
LOCAL WIND FLOW OVER THE ISLANDS HAS VEERED TO THE EAST-SOUTHEAST
AS THE HIGH RETREATS EASTWARD AND THE FRONT ADVANCES INTO THE NW
HAWAIIAN ISLANDS. ALOFT...A MID/UPPER LEVEL TROUGH IS MOVING
EASTWARD NEAR 175W... WITH THE SUBTROPICAL RIDGE SUPPRESSED SOUTH
OF 10N. MIMIC-TPW SATELLITE IMAGERY DEPICTS A RATHER DRY
ATMOSPHERE SURROUNDING THE ISLANDS...WITH ESTIMATED PWATS AROUND
1.2 INCHES. THE 00Z SOUNDINGS SHOW SIGNIFICANT COOLING ALOFT IN
ADVANCE OF THE UPPER LEVEL TROUGH...BUT THE LOW LEVELS REMAIN
STABLE WITH INVERSIONS BASED AROUND 7500 FEET...AND MOISTURE IS
LIMITED WITH PWATS BETWEEN 1.1 AND 1.2 INCHES.

OVERNIGHT...SOUTHEAST LOW LEVEL FLOW SHOULD CONTINUE TO FAVOR
SHOWERS OVER THE SAME AREAS ON OAHU AND THE BIG ISLAND...WITH
MAINLY DRY CONDITIONS ELSEWHERE AS THE SMALLER ISLANDS WILL BE
SHADOWED BY THE BIG ISLAND. WILL KEEP AN EYE ON WINDWARD OAHU...
WHERE INSTABILITY ALOFT AND A FAVORABLE FLOW PATTERN COULD TRIGGER
A FEW HEAVIER SHOWERS LATER TONIGHT. THE EXISTING FORECAST APPEARS
TO BE ON TRACK...AND NO CHANGES ARE PLANNED FOR THIS EVENING.

WINDS WILL BECOME LIGHT AND VARIABLE OVER THE STATE ON TUESDAY...
AS THE COLD FRONT APPROACHES FROM THE NW. THIS WILL ALLOW
WIDESPREAD SEA BREEZES TO DEVELOP OVER THE ISLANDS. INSTABILITY
ALOFT WILL BE MAXIMIZED AS THE UPPER TROUGH MOVES OVERHEAD...
BUT MOISTURE WILL REMAIN QUITE LIMITED AND THE LOW LEVELS WILL
LIKELY REMAIN RATHER STABLE. AN ISOLATED HEAVIER SHOWER WILL
BE POSSIBLE DURING THE AFTERNOON...BUT DO NOT EXPECT ANYTHING MORE
THAN THAT. THE AREA EXPECTED TO SEE THE MOST PERSISTENT RAINFALL
ON TUESDAY WILL BE SOUTHEAST FACING SLOPES OF THE BIG ISLAND...
DUE TO UPSLOPE LOW LEVEL FLOW INTO THE TERRAIN.

MODELS REMAIN IN GOOD AGREEMENT WITH THE TIMING OF THE FRONTAL
PASSAGE TUESDAY NIGHT INTO WEDNESDAY...WITH THE FRONT REACHING
KAUAI TUESDAY EVENING...OAHU AFTER MIDNIGHT...MAUI COUNTY EARLY
WEDNESDAY MORNING...AND THE BIG ISLAND LATE MORNING AND AFTERNOON.
THIS FRONT WILL BE QUITE SHALLOW WITH LIMITED MOISTURE
AVAILABLE...SO EXPECT LIMITED RAINFALL MAINLY ON NORTH FACING
SLOPES. BEHIND THE FRONT...EXPECT ANOTHER ROUND OF COOL AND
BREEZY NORTHERLY WINDS AS HIGH PRESSURE BUILDS TO THE NORTHWEST
OF THE STATE. THESE BREEZY CONDITIONS WILL PERSIST THROUGH
THURSDAY...WITH DEWPOINTS DROPPING WELL INTO THE 50S ACROSS
MOST OF THE STATE. AT THIS POINT...IT APPEARS THAT WINDS WILL
PROBABLY REMAIN BELOW ADVISORY LEVELS EXCEPT PERHAPS FOR A FEW
ISOLATED GUSTS AT TIMES. MAX WIND GUSTS FOR MOST AREAS SHOULD BE
IN THE 30 TO 45 MPH RANGE.

THERE IS SOME INDICATION IN THE LATEST MODELS THAT THE FRONT MAY
NOT BE ABLE TO CLEAR PAST THE SOUTHEAST BIG ISLAND...AND RAIN
CHANCES MAY REMAIN HIGHER THERE DURING THE MIDDLE AND LATER PART
OF THIS WEEK. DRY CONDITIONS SHOULD PREVAIL ELSEWHERE ACROSS THE
STATE.

MORE TYPICAL TRADE WIND CONDITIONS SHOULD PREVAIL DURING THE
WEEKEND...AS HIGH PRESSURE SHIFTS SLOWLY EASTWARD TO THE NORTH OF
THE STATE. MODEL FORECASTS SHOW BELOW NORMAL PWATS WITH WEAK MID
LEVEL RIDGING OVERHEAD...SO WOULD EXPECT RAINFALL TO REMAIN
GENERALLY LIGHT EVEN ACROSS THE WINDWARD AREAS...WITH MAINLY
DRY CONDITIONS ELSEWHERE.

&&

.AVIATION...
THE LOW-LEVEL FLOW HAS WEAKENED AND STARTED TO VEER SOUTHEASTERLY
AHEAD OF THE NEXT FRONT...AND SEVERAL LOCATIONS DEVELOPED SEA
BREEZES MONDAY AFTERNOON. AN EVEN LIGHTER GRADIENT IS EXPECTED
ON TUESDAY...ALLOWING FOR WIDESPREAD SEA BREEZES BY AFTERNOON.

AIRMET SIERRA FOR MOUNTAIN OBSCURATION HAS BEEN POSTED FOR
WINDWARD OAHU DUE TO PERSISTENT SHOWERS AND CLOUDS...AND MAY BE
NEEDED OVERNIGHT FOR THE SOUTHEAST BIG ISLAND.

NORTHERLY WINDS WILL INCREASE BEHIND THE FRONT LATE TUESDAY NIGHT
AND WEDNESDAY...WITH LOW-LEVEL SPEEDS OF 25-30 KNOTS POSSIBLE
AGAIN. INVERSION HEIGHTS ARE ALSO EXPECTED TO DROP BELOW 4000 FT.
THIS COULD LEAD TO ANOTHER PERIOD OF LOW-LEVEL TURBULENCE
BEGINNING LATE TUESDAY NIGHT...WITH THE POTENTIAL INCREASING
FURTHER ON WEDNESDAY. INITIALLY THE GREATEST TURBULENCE THREAT
WILL BE LOCATED SOUTH OF THE ISLANDS...THEN TRANSITION TO A MORE
TYPICAL SOUTH THROUGH WEST AS THE WIND VEERS TO THE NORTHEAST
DURING THE LATER PART OF THE WEEK.

&&

.MARINE...
EASTERLY TRADE WINDS WILL CONTINUE TO DECREASE AND VEER TO THE
SOUTHEAST THROUGH THE NIGHT...AND THE NORTH-NORTHWEST SWELL WILL
CONTINUE TO DECLINE. WINDS WILL BECOME VARIABLE ON TUESDAY AHEAD
OF AN APPROACHING FRONT...WITH A RAPID INCREASE IN NORTHERLY WINDS
TUESDAY NIGHT AND WEDNESDAY BEHIND THE FRONT. STRONG AND GUSTY
NORTHEAST WINDS WILL CONTINUE ON THURSDAY. AN SCA WILL LIKELY BE
POSTED FOR ALL WATERS IN THE WAKE OF THE FRONT...WITH THE COVERAGE
TRIMMED BACK TO THE TYPICALLY WINDY WATERS AROUND THE BIG ISLAND
AND MAUI BY FRIDAY OR THE WEEKEND.

THE NEXT SIGNIFICANT SWELL WILL BE FROM THE PARENT LOW ASSOCIATED
WITH THE FRONT THAT WILL AFFECT THE ISLANDS. THE SWELL WILL BE OUT
OF THE NORTH AND WILL BE MIXED WITH LARGE WIND WAVES PRODUCED BY
EXPECTED STRONG NORTHERLY WINDS. THIS COULD PRODUCE ADVISORY LEVEL
SURF WEDNESDAY NIGHT AND THURSDAY ACROSS EXPOSED EASTERN
SHORELINES AND SOME SURGES IN NORTH FACING HARBORS. THE NORTH
SWELL MAY BUILD FURTHER FRIDAY INTO THE WEEKEND...WITH A MODERATE
NORTHWEST SWELL ARRIVING DURING THE WEEKEND AS WELL. THIS WOULD
LIKELY RESULT IN ADVISORY LEVEL SURF EXPANDING FROM EXPOSED EAST
FACING SHORES TO NORTH SHORES. IN ADDITION...SMALL SOUTH SWELLS
ARE EXPECTED TO CONTINUE THROUGH THIS WEEK. PLEASE REFER TO THE
LATEST COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST /SRDHFO/
FOR MORE DETAILS.

&&

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

&&

JACOBSON