Small Craft Advisory 35, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1002 AM HST WED JUL 22 2015

.SYNOPSIS...
LIGHT EAST SOUTHEAST WIND FLOW WILL CONTINUE ACROSS THE ISLANDS
TODAY. A SOMEWHAT UNSTABLE AIRMASS ALONG WITH SUFFICIENT MOISTURE AT
THE SURFACE WILL LIKELY RESULT IN MODERATE TO HEAVY SHOWERS AT
TIMES TODAY...MOSTLY FOR THE WESTERN PORTION OF THE STATE. MORE
TYPICAL TRADE WINDS WILL RETURN ACROSS THE AREA LATE THURSDAY...AND
BRIEFLY STRENGTHEN FROM THURSDAY NIGHT THROUGH FRIDAY. AN INCREASE
IN SHOWERS AND HUMIDITY IS EXPECTED THIS WEEKEND AS REMNANT MOISTURE
FROM FORMER TROPICAL CYCLONE ENRIQUE MOVES ACROSS THE STATE.

&&

.DISCUSSION...
AN UPPER LEVEL LOW IS CENTERED AROUND 800 MILES NORTHWEST OF KAUAI
THIS MORNING...MOVING WEST AWAY FROM THE ISLANDS. THE AFFECTS OF
THIS LOW IS OBSERVED IN THE EARLY MORNING SOUNDINGS...PARTICULARLY
AT LIHUE WHERE THERE IS NO MIDLEVEL INVERSION. PRECIPITATABLE
WATER VALUES ARE AN ABOVE AVERAGE 1.87 INCHES. THE UPPER LOW IS
INDUCING A WEAK LOW LEVEL AND SURFACE TROUGH WEST OF THE
STATE...BUT IT/S WESTWARD PROGRESSION HAS PUSHED MOST OF THE
CLOUDS AND SHOWERS WEST OF THE AREA THIS MORNING. EXPECT
DECREASING SHOWERS THROUGH THE EARLY AFTERNOON TODAY. THE PRESENCE
OF THE UPPER LOW AND AVAILABLE LOW LEVEL MOISTURE MAY STILL
TRIGGER SOME HEAVY AFTERNOON SHOWERS AS SEA BREEZE CONVERGENCE
SETS IN. THE HIGHEST CHANCES FOR ANY CONVECTION LATER TODAY WILL
BE ACROSS KAUAI...WITH A LESSER CHANCE FOR SHOWERS EASTWARD DOWN
THE ISLAND CHAIN. LIGHT EAST-SOUTHEAST BACKGROUND FLOW WILL
KEEP ANY HEAVY SHOWERS THAT DO POP UP TO MOVE SLOW OR NEARLY
STATIONARY WHICH MAY PRODUCE LOCALIZED PONDING OR FLOODING.

THE UPPER LEVEL LOW WILL MOVE A BIT FURTHER NORTHWEST BY THURSDAY...ALLOWING
THE AIRMASS ACROSS THE ISLANDS TO BECOME MORE STABLE. THE SURFACE
TROUGH WILL SHIFT FURTHER WEST AS WELL...ALLOWING THE RETURN OF
STRONGER MORE EASTERLY TRADE WINDS TO THE ISLANDS LATE IN THE DAY
THURSDAY. AS THE WINDS STRENGTHEN...CLOUDS AND SHOWERS WILL ONCE
AGAIN BECOME FOCUSED OVER WINDWARD AND MAUKA AREAS.

LONG RANGE MODELS STILL SUGGEST MOISTURE AND A WEAK TROUGH ASSOCIATED
WITH THE REMNANTS OF FORMER EAST PACIFIC TROPICAL CYCLONE ENRIQUE
MAY PASS THE STATE DURING THE WEEKEND. MOISTURE MAY LINGER AROUND
EVEN INTO EARLY NEXT WEEK. WE CAN EXPECT AN INCREASE IN SHOWERS AS
WELL AS HUMIDITY ALONG WITH WEAKENED TRADE WINDS FOR THE BIG
ISLAND AS EARLY AS FRIDAY...AND THE REST OF THE STATE THROUGH THE
WEEKEND. UPPER LEVEL RIDGING OVER THE STATE THIS WEEKEND WILL KEEP
THE SHOWERS ON THE LIGHT TO MODERATE INTENSITY.

&&

.AVIATION...
MORNING SHOWERS OVER KAUAI AND OAHU WILL CONTINUE TO DIMINISH OVER
THE NEXT FEW HOURS. AIRMET SIERRA FOR MTN OBSC OVER KAUAI WILL
LIKELY BE CANCELLED BEFORE THE NEXT ROUTINE ISSUANCE AS CONDITIONS
IMPROVE. TERMINALS...INCLUDING PHLI...PHJR...AND PHNL CAN EXPECT
MAINLY BROKEN TO OVERCAST MID LEVEL CLOUDS INTO THE AFTERNOON WITH
FEW TO SCATTERED CLOUDS NEAR 2 THOUSAND FEET. WINDWARD AREAS ON THE
BIG ISLAND AND MAUI CAN EXCEPT LOW CLOUDS TO BANK UP ALONG THEIR
SLOPES...WITH TEMPO MVFR CONDITIONS POSSIBLE AND THE CHANCE FOR
AIRMET SIERRA FOR MTN OBSC CAN NOT BE RULED OUT COMPLETELY. THEY
WILL BE ISSUED AS NEEDED. OTHERWISE...VFR CONDITIONS WILL
PREVAIL...WITH ONLY BRIEF MVFR IN PASSING SHOWERS.

&&

.MARINE...
WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY /SCA/ LEVELS
FOR ALL COASTAL WATERS THROUGH THURSDAY. TRADE WINDS WILL BRIEFLY
BUILD ON THURSDAY NIGHT AND FRIDAY...AND BECOME STRONG ENOUGH SUCH
THAT SCA CONDITIONS MAY BE REACHED FOR THE TYPICAL WINDY ZONES
AROUND MAUI COUNTY AND THE BIG ISLAND. WINDS ARE EXPECTED TO EASE
AGAIN OVER THE WEEKEND AS REMNANTS OF FORMER TROPICAL CYCLONE PASS
THE ISLANDS.

A NORTHEAST SWELL WILL BRING ELEVATED SURF ALONG BOTH NORTH AND EAST
FACING SHORES THROUGH THURSDAY. A HIGH SURF ADVISORY REMAINS IN
EFFECT FOR EAST FACING SHORES TODAY. SURF HEIGHTS ALONG EAST FACING
SHORES ARE EXPECTED TO DROP BELOW ADVISORY LEVEL BY THIS EVENING.

A LARGE SOUTH SWELL IS ANTICIPATED TO ARRIVE IN HAWAII FRIDAY AND
WILL BE LARGE ENOUGH TO BRING ADVISORY...AND POSSIBLE WARNING
LEVEL SURF HEIGHTS ALONG SOUTH FACING SHORES THIS WEEKEND.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR EAST FACING
SHORES OF KAUAI OAHU MOLOKAI MAUI AND THE BIG ISLAND.

&&

DISCUSSION/MARINE...FOSTER
AVIATION...EATON