Small Craft Advisory 14, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
951 AM HST TUE MAR 15 2016

.SYNOPSIS...
LIGHT SOUTHEAST BACKGROUND FLOW AHEAD OF AN APPROACHING FRONT
TODAY WILL RESULT IN WIDESPREAD SEA BREEZES AND SCATTERED SHOWERS
DEVELOPING OVER THE ISLANDS THIS AFTERNOON. MINIMAL RAINFALL IS
EXPECTED ALONG THE FRONT AS IT MOVES THROUGH THE STATE TONIGHT
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...
VISIBLE SATELLITE AND RADAR SHOWS SCATTERED LIGHT SHOWERS ACROSS
THE SOUTHEASTERN PORTIONS OF BOTH MAUI AND THE BIG ISLAND THIS
MORNING...WHILE THE REST OF THE STATE IS SUNNY. LIGHT BACKGROUND
SOUTHEAST FLOW PREVAILS WHICH IS ANCHORING THE SHOWERS OVER THE
AFOREMENTIONED AREAS. EXPECT TO SEE INCREASING CLOUDINESS THIS
AFTERNOON AS SEA BREEZES CONVERGE OVER THE ISLANDS BRINGING
INTERIOR CLOUDS AND SHOWERS. MIMIC-TPW SATELLITE IMAGERY DEPICTS
A RATHER DRY ATMOSPHERE SURROUNDING THE ISLANDS...WITH ESTIMATED
PWATS AROUND 1.2 INCHES.

A COLD FRONT IS LOCATED ABOUT 500 MILES NORTHWEST OF KAUAI AT THIS
TIME AND IS RAPIDLY ADVANCING SOUTHEAST TOWARDS THE STATE. THE
PARENT SURFACE IS LOW IS ABOUT 900 MILES DUE NORTH OF KAUAI THIS
MORNING. WATER VAPOR IMAGERY ALSO SHOWS AN EASTWARD MOVING TROUGH
ALOFT ASSOCIATED WITH THIS SYSTEM NORTHWEST OF THE STATE...BUT MOST
OF THE DYNAMIC FORCING FROM THE TROUGH REMAINS WELL TO THE NORTH.

INSTABILITY ALOFT WILL BE MAXIMIZED AS THE UPPER TROUGH MOVES
BY...BUT MOISTURE WILL REMAIN QUITE LIMITED AND THE LOW LEVELS
WILL LIKELY REMAIN RATHER STABLE. AN ISOLATED HEAVIER SHOWER WILL
BE POSSIBLE THIS AFTERNOON...BUT DO NOT EXPECT ANYTHING TOO
SIGNIFICANT. THE AREA EXPECTED TO SEE THE MOST PERSISTENT RAINFALL
LATER TODAY 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 TONIGHT INTO WEDNESDAY...WITH THE FRONT REACHING KAUAI
THIS EVENING...OAHU AROUND 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 SIGNIFICANT RAINFALL TO BE CONFINED MAINLY TO THE 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 WEDNESDAY NIGHT AND
THURSDAY...WITH DEWPOINTS DROPPING WELL INTO THE 50S ACROSS MOST
OF THE STATE. IT APPEARS THAT WINDS WILL PROBABLY REMAIN BELOW
ADVISORY LEVELS FOR MOST AREAS WITH MAX WIND GUSTS IN THE 30 TO 45
MPH RANGE. HOWEVER...THERE WILL BE LOCALIZED AREAS PRONE TO
STRONGER WINDS DUE TO TERRAIN ENHANCEMENT...WHICH INCLUDE SOUTH
FACING MOUNTAIN SLOPES DUE TO DOWNSLOPING GUSTS...AS WELL AS THE FAR
EAST AND WEST POINTS OF EACH ISLAND. WE ARE ALSO CONSIDERING A
WIND ADVISORY FOR WEDNESDAY FOR LANAI AS STRONG NORTH/NORTHEAST
FLOW PATTERN IS FAVORABLE FOR STRONG WINDS. FOR NOW...HAVE A
SPECIAL WEATHER STATEMENT IN EFFECT TO HIGHLIGHT THE UPCOMING
PERIOD OF WINDY/COOL WEATHER.

THE FRONT WILL STALL OUT NEAR THE BIG ISLAND WEDNESDAY NIGHT.
MODELS SHOW THE FRONT HANGING OVER OR JUST TO THE SOUTHEAST OF THE
BIG ISLAND THROUGH THE END OF THE WORK WEEK. WITH TRADES BUILDING
BACK IN...RAIN CHANCES WILL BE HIGHER FOR THE WINDWARD BIG ISLAND
SLOPES ON THURSDAY AND FRIDAY. MAINLY DRY CONDITIONS ASSOCIATED
WITH THE HIGH PRESSURE 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.

FORECAST MODELS DIVERGE EARLY NEXT WEEK...WHEN THE ECMWF IS MUCH
STRONGER THAN OTHER GUIDANCE WITH A DEVELOPING MID LEVEL CUTOFF
LOW AND ASSOCIATED SURFACE LOW OVER THE NORTH CENTRAL PACIFIC. IT
DOES APPEAR THAT OUR LOCAL FLOW WILL VEER AROUND TO THE SOUTH ONCE
AGAIN WITH INCREASING MOISTURE AND AT LEAST SCATTERED SHOWERS FOR
MANY AREAS...BUT WE WILL HAVE TO WAIT AND SEE IF THE MUCH STRONGER
EC SOLUTION PERSISTS DURING THE NEXT SEVERAL DAYS.

&&

.AVIATION...
A LIGHT WIND REGIME WILL REMAIN IN PLACE TODAY AS A COLD FRONT
APPROACHES FROM THE NORTHWEST. THIS WILL ALLOW SEA BREEZES TO
DEVELOP IN MOST AREAS...WITH SHOWERS FOCUSED PRIMARILY ACROSS THE
INTERIOR OF THE ISLANDS. CAN/T RULE OUT SOME BRIEF MVFR CIGS IN
-SHRA AT THE TERMINALS IN ADVANCE OF THE FRONT...BUT GENERALLY VFR
CONDITIONS ARE EXPECTED. AT PHTO HOWEVER...SOME MVFR CIGS/VSBYS WILL
BE POSSIBLE IN -SHRA THIS MORNING...AND SOME MVFR CIGS WILL BE
POSSIBLE THROUGH MUCH OF THE DAY AT PHNY. THE FRONT WILL MOVE
THROUGH KAUAI EARLY THIS EVENING...THEN THROUGH OAHU AND MAUI COUNTY
OVERNIGHT. MVFR CIGS/VSBYS IN SHRA WILL BE POSSIBLE IN ASSOCIATION
WITH THE FRONT AS IT MOVES THROUGH THE AREA. WINDS WILL PICK UP OUT
OF THE NORTH AND BECOMING BREEZY BEHIND THE FRONT AS WELL.

AIRMET SIERRA IS IN EFFECT FOR MOUNTAIN OBSCURATION ACROSS WINDWARD
SECTIONS OF THE BIG ISLAND. CONDITIONS ARE EXPECTED TO IMPROVE HERE
BY LATE THIS MORNING OR EARLY THIS AFTERNOON. MOUNTAIN OBSCURATION
MAY BECOME AN ISSUE ONCE AGAIN TONIGHT AS THE COLD FRONT MOVES
THROUGH THE AREA.

AIRMET TANGO WILL LIKELY BE NEEDED LATE TONIGHT FOR LOW LEVEL TURB
AS WINDS PICK UP OUT OF THE NORTH BEHIND THE COLD FRONT.

&&

.MARINE...
WINDS WILL BECOME VARIABLE ACROSS THE COASTAL WATERS TODAY
AHEAD OF AN APPROACHING FRONT...WITH A RAPID INCREASE IN
NORTHERLY WINDS LATE TONIGHT AND WEDNESDAY BEHIND THE FRONT.
STRONG AND GUSTY NORTHEAST WINDS WILL CONTINUE ON THURSDAY. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR ALL WATERS IN THE
WAKE OF THE FRONT FOR WEDNESDAY AND THURSDAY...WITH THE COVERAGE
EVENTUALLY 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
FROM 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.

&&

DISCUSSION/MARINE...FOSTER
AVIATION...JELSEMA