High Surf Advisory 15, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST TUE FEB 14 2012

.SYNOPSIS...
A SURFACE RIDGE NEAR THE ISLANDS WILL BRING LIGHT WINDS THROUGH
WEDNESDAY. THE LIGHT WINDS WILL ALLOW CLOUDS TO FORM OVER THE
ISLANDS WEDNESDAY AFTERNOON...BUT THE ATMOSPHERE WILL BE STABLE...SO
RAINFALL WILL BE LIGHT. TRADE WINDS WILL RETURN WEDNESDAY NIGHT AS
THE RIDGE MOVES NORTH AND STRENGTHENS. WINDWARD SHOWERS WILL
RETURN WITH THE TRADE WINDS. THE SHOWERS MAY BECOME MORE ACTIVE
FRIDAY THROUGH THE WEEKEND AS A LOW ALOFT APPROACHES THE BIG
ISLAND FROM THE SOUTHEAST.

&&

.DISCUSSION...
A SURFACE HIGH IS LOCATED FAR NORTHEAST OF THE AREA NEAR 32N140W.
A RIDGE EXTENDS WEST SOUTHWEST FROM THE HIGH TO ABOUT 150 MILES
NORTH OF KAUAI. MODERATE TRADE WINDS ARE BLOWING NEAR THE BIG
ISLAND WITH GENTLE EAST SOUTHEAST FLOW OVER THE SMALLER ISLANDS. A
DRY AND STABLE ATMOSPHERE ALOFT IS KEEPING SHOWERS SUPPRESSED.

CLOUDS REMAIN OVER THE ISLANDS THIS EVENING FROM EARLIER DAYTIME
HEATING. RADAR ALSO SHOWS A COUPLE OF ISOLATED SHOWERS PRESENT
ACROSS OAHU AND MOLOKAI BUT SHOULD ONLY PRODUCE VERY BRIEF SHOWERS
AT BEST. BOTH THE CLOUDS AND SHOWERS SHOULD DISSIPATE IN THE NEXT
FEW HOURS AS LAND BREEZES CLEAR AWAY MUCH OF THE CLOUDINESS OVER
THE ISLANDS. HOWEVER...EASTERN SIDES OF MAUI AND THE BIG ISLAND
COULD GET CLOUDS MOVING IN FROM THE EAST OVERNIGHT GIVEN CURRENT
SATELLITE TRENDS.

THE RIDGE WILL REMAIN NEAR THE ISLANDS THROUGH WEDNESDAY EVENING.
THIS MEANS MODERATE TRADE WINDS WILL CONTINUE NEAR THE BIG ISLAND
BUT SOUTHEAST WINDS OVER THE SMALLER ISLANDS WILL BE PARTLY
BLOCKED BY THE BIG ISLAND. THIS PATTERN WILL KEEP THE PREVAILING
FLOW LIGHT ENOUGH TO ALLOW LAND AND SEA BREEZES TO DOMINATE OVER
THE SMALLER ISLANDS WEDNESDAY. THE LIGHT PREVAILING FLOW WILL
ALLOW DAYTIME SEA BREEZES THROUGH WEDNESDAY. THE SEA BREEZES WILL
BRING CLOUDY SKIES WEDNESDAY AFTERNOON BUT THE ATMOSPHERE WILL BE
TOO STABLE FOR MUCH RAINFALL TO RESULT.

TRADE WINDS WILL SPREAD BACK OVER THE SMALLER ISLANDS STARTING
WEDNESDAY NIGHT AS THE SURFACE RIDGE STRENGTHENS AND MOVES
NORTH...SO WOULD EXPECT MORE CLOUDS ACROSS WINDWARD SLOPES
TOMORROW NIGHT VERSUS TONIGHT. THE TRADE WINDS WILL BECOME LOCALLY
BREEZY ON THURSDAY. WINDS MAY REACH ADVISORY LEVELS OVER HALEAKALA
SUMMIT AS THE TRADE WINDS STRENGTHEN. WINDWARD SHOWERS WILL RETURN
AS THE TRADES BUILD BACK. RAINFALL WILL BE MODERATE ON THURSDAY
BUT SHOWERS WILL BECOME MORE ACTIVE STARTING FRIDAY AS A LOW
ALOFT APPROACHES FROM THE SOUTHEAST. THIS PERIOD OF ACTIVE TRADE
WIND SHOWERS WILL CONTINUE INTO THE WEEKEND. WINDWARD SLOPES WILL
BE THE FOCUS...BUT ELEVATED WINDS WILL CARRY SHOWERS TO LEEWARD
SIDES OF THE SMALLER ISLANDS OCCASIONALLY. RAINFALL SHOULD BE MOST
ACTIVE AROUND THE BIG ISLAND SINCE IT WILL BE CLOSEST TO THE LOW.
MOISTURE NEAR THE BIG ISLAND MAY GET DEEP ENOUGH TO BRING
PRECIPITATION TO THE BIG ISLAND SUMMITS AND TEMPERATURES ARE
LIKELY TO BE COLD ENOUGH FOR SNOW OR ICE.

THE GFS AND ECMWF MODELS BOTH SHOW THE SURFACE RIDGE MOVING BACK
DOWN CLOSER TO THE ISLANDS EARLY NEXT WEEK. THAT WILL CAUSE THE
WINDS TO WEAKEN AND SHIFT TO SOUTHEAST AGAIN. AT THE SAME TIME THE
LOW ALOFT SHOULD SHIFT FARTHER SOUTH SO THE ATMOSPHERE IS LIKELY
TO STABILIZE.

&&

.MARINE...
SURF HAS DROPPED BELOW THE ADVISORY THRESHOLD. ANOTHER NORTHWEST
SWELL ARRIVING TOMORROW WILL BRING SURF BACK UP WELL ABOVE THE
ADVISORY /HSA/ THRESHOLD ALONG NORTH AND WEST FACING SHORES.
MONITORING BUOYS TONIGHT AND WILL LIKELY ISSUE AN HSA TOMORROW
MORNING. STRENGTHENING TRADE WINDS THURSDAY COULD PRODUCE BIG
ENOUGH ROUGH SURF ALONG EAST FACING SHORES TO REQUIRE AND ADVISORY
BY THE WEEKEND.

AS THE NORTHWEST SWELL BUILDS...A SMALL CRAFT ADVISORY IS LIKELY TO
BE REQUIRED STARTING WEDNESDAY NIGHT. THE ADVISORY IS LIKELY TO BE
EXPANDED THURSDAY AS THE TRADE WINDS STRENGTHEN.

&&

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

&&

FOSTER