000
FXHW60 PHFO 180646
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
845 PM HST FRI MAY 17 2013

.SYNOPSIS...
TRADE WINDS WILL WEAKEN TONIGHT AND SATURDAY...AS LOW PRESSURE
DEVELOPS NORTH OF THE ISLANDS. THE WEAK LOW WILL TURN WINDS TO THE
NORTH ON KAUAI AND OAHU BY SATURDAY NIGHT...WITH LIGHT SOUTH WINDS
NEAR THE BIG ISLAND. WITH LIGHT WINDS...CLOUDS AND SHOWERS WILL
FAVOR AFTERNOON HOURS...AND THE INTERIOR AND UPSLOPE AREAS. THE
PRESENCE OF THE LOW WILL HELP TO INTENSIFY ANY SHOWERS THAT FORM
OVER THE ISLANDS FOR THE NEXT SEVERAL DAYS.

&&

.DISCUSSION...
CURRENTLY...WATER VAPOR IMAGERY SHOWS A CLOSED LOW ALOFT CENTERED
NEAR OAHU...MOVING SLOWLY TOWARD THE ESE AT ABOUT 5 MPH. AT THE
SURFACE...MODERATE TRADE WINDS ARE BEING SUPPORTED BY A SURFACE
HIGH CENTERED ABOUT 1300 MILES NE OF THE ISLANDS. THE PRESENCE
OF THE LOW ALOFT HAS DESTABILIZED THE ISLAND AIRMASS...AND IS
ENHANCING BOTH THE INCOMING TRADE WIND SHOWERS...AND THE SHOWERS
LINGERING OVER THE KONA SLOPES THAT FORMED IN RESPONSE TO AFTERNOON
SEABREEZES AND UPSLOPE FLOW. MEANWHILE...WATER VAPOR AND INFRARED
IMAGERY SHOW A DEVELOPING AREA OF LOW PRESSURE ABOUT 600 MILES NORTH
OF THE ISLANDS...NEAR 30N 158W...WHICH WILL BECOME AN IMPORTANT
PLAYER IN ISLAND WEATHER OVER THE NEXT SEVERAL DAYS.

THE FORECAST CALLS FOR THE CURRENT UPPER LOW TO MOVE ESE WHILE
SLOWLY WEAKENING THROUGH SATURDAY...WHILE A NEW TROUGH ALOFT DIGS
AGGRESSIVELY SE OVER WATERS NW AND N OF THE ISLANDS. THIS STRONGLY
DIGGING TROUGH WILL HELP TO DEVELOP A CLOSED LOW ALOFT THAT WILL
MEANDER IN A POSITION ABOUT 550 MILES NE OF THE ISLANDS FROM LATE
SATURDAY INTO THE MIDDLE OF NEXT WEEK. THE PROXIMITY OF THE CLOSED
LOW WILL MAINTAIN A MODERATELY UNSTABLE ISLAND AIRMASS...AND
ENHANCE ANY SHOWERS THAT DEVELOP. THE LOW WILL LINGER N OF THE
ISLANDS UNTIL THE MIDDLE OF NEXT WEEK BEFORE FINALLY DISSIPATING.

A WEAK SURFACE LOW IS FORECAST TO DEVELOP IN RESPONSE TO THE
DEVELOPING LOW ALOFT TO THE N OF THE ISLANDS...WITH A SURFACE TROUGH
EXTENDING S OVER THE ISLANDS. THIS WILL INTERRUPT THE TRADE FLOW
OVER THE NEXT 24 HOURS... AND ALTHOUGH THERE IS SOME UNCERTAINTY AS
TO WHERE THE TROUGH AXIS WILL LIE...LATEST GUIDANCE INDICATES THAT
LIGHT TO MODERATE WINDS WILL TURN TO THE N OVER KAUAI AND OAHU BY
SUNDAY...WITH S WINDS NEAR THE BIG ISLAND. AWAY FROM THE MODERATE N
FLOW ON KAUAI...LAND AND SEA BREEZE CIRCULATIONS WILL DOMINATE WIND
FLOW OVER THE ISLANDS. THIS MEANS AFTERNOON CLOUDS AND SHOWERS OVER
THE ISLANDS BOTH SATURDAY AND SUNDAY...WITH PARTIAL CLEARING AT
NIGHT. THE TROUGH AXIS WILL MEANDER IN CONNECTION WITH THE
MEANDERING LOW ALOFT TO THE N AS WE HEAD INTO NEXT WEEK...AND
DETAILS ON THE LOW LEVEL WIND DIRECTION ARE UNCERTAIN...BUT
CONFIDENCE IS HIGH THAT WINDS WILL REMAIN LIGHT OVER THE
ISLANDS...AND A CONTINUATION OF THE DIURNAL CONVECTIVE WEATHER
PATTERN IS EXPECTED TO CONTINUE INTO NEXT WEEK. THERE ARE SOME MINOR
DIFFERENCES AMONG THE MODELS ABOUT HOW UNSTABLE IT WILL BE AFTER
SUNDAY HOWEVER.

IT APPEARS RIGHT NOW AS THOUGH THE MID LEVELS OF THE ATMOSPHERE
WILL STAY A LITTLE TOO WARM TO SUPPORT THUNDERSHOWERS...THOUGH IF
THESE WERE TO OCCUR THE BEST CHANCE WOULD BE OVER THE LEEWARD
SLOPES AND INTERIOR PORTIONS OF THE BIG ISLAND EACH AFTERNOON THIS
WEEKEND. IN OTHER AREAS...LOCALIZED DOWNPOURS ARE POSSIBLE...
PARTICULARLY IN THE AFTERNOONS.

&&

.AVIATION...
CLOUDS AND SHRA OVER WINDWARD AREAS WILL BRING TEMPO MVFR AND ISOL
IFR CONDITIONS...AND ISOL MVFR OVER LEEWARD WATERS. TRADE WINDS WILL
DECREASE THROUGH TONIGHT AND TOMORROW WITH SEA BREEZES EXPECTED OVER
LEEWARD LOCATIONS IN THE AFTERNOON. CLOUDS AND SHRA WILL INCREASE
OVER INTERIOR SECTIONS SATURDAY AFTERNOON.

&&

.MARINE...
WITH TRADE WINDS DIMINISHING...THE SMALL CRAFT ADVISORY /SCA/ FOR
WINDIER MARINE ZONES AROUND MAUI AND THE BIG ISLAND WAS ALLOWED TO
EXPIRE A SHORT WHILE AGO. WINDS AND SEAS ARE EXPECTED TO REMAIN
BELOW SCA CRITERIA UNTIL AT LEAST THE MIDDLE OF NEXT WEEK.

BIGGEST MARINE HIGHLIGHT IS THE HIGH SURF ALONG S FACING SHORES OF
ALL ISLANDS...WITH A HIGH SURF ADVISORY IN EFFECT THROUGH THE
WEEKEND. HOWEVER...A SERIES OF S SWELLS WILL KEEP ELEVATED SURF
ALONG S FACING SHORES THROUGH MOST OF THE UPCOMING WEEK. A SMALL NW
SWELL IS EXPECTED THIS WEEKEND...WITH A MODERATE NW SWELL BUILDING
TUESDAY AND PEAKING WEDNESDAY.

&&

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

&&

$$

DISCUSSION/MARINE...BIRCHARD
AVIATION...MORRISON

000
ATHW40 PHFO 180540
SIMHI

HAWAIIAN ISLANDS SATELLITE INTERPRETATION MESSAGE
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
0530 UTC SAT MAY 18 2013

BASED ON DATA THROUGH 0500 UTC MAY 18 2013

ANIMATION OF THE WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW OVER
THE NORTHERN PORTION OF THE KAUAI CHANNEL AT 22N158W. IT IS DRIFTING
SOUTHEASTWARD TOWARDS OAHU. A FIELD OF HIGH LEVEL CIRRUS EXTENDED
NORTHEAST OF THE UPPER LOW FOR 400 MILES. MORE CIRRUS CLOUDS ARE
NOTED ON WATER VAPOR NORTHWEST OF THE ISLANDS.

ALSO ON WATER VAPOR IS A RIBBON OF DENSE CIRRUS IS PASSING SOUTH OF
THE BIG ISLAND. THE CIRRUS COMES FROM THUNDERSTORMS LOCATED ALONG
THE INTERTROPICAL CONVERGENCE ZONE /ITCZ/ LOCATED ALONG 05N
LATITUDE. THE RIBBON OF CIRRUS IS 350 WIDE...AND IS CAUGHT IN A
SOUTHWEST FLOW ALOFT.

INFRARED IMAGERY SHOWS THE EASTERN HALF OF THE ISLAND CHAIN BEING
BOTHERED BY A FIELD OF BROKEN LOW CLOUDS. THIS FIELD EXTENDED
NORTHWARD OF MAUI FOR 300 MILES...470 MILES TO THE WEST AND 600
MILES TO THE EAST OF THE BIG ISLAND. ANIMATION OF THE INFRARED
IMAGERY SHOWS A SLIGHT NORTH TO SOUTH ORIENTED TROUGH CENTERED OVER
MAUI COUNTY. THE LOW LEVEL WIND FLOW WEST OF OF THE TROUGH IS
FROM THE EAST NORTHEAST...AND FROM THE SOUTHEAST EAST OF THE TROUGH.
WIND SPEED IS 15 TO 20 MPH OVER THE WINDWARD WATERS.

ASIDE FOR LOCALLY BROKEN LOW CLOUDS STRADDLING THE MOUNTAINS...SKIES
WERE FAIR ACROSS KAUAI OAHU AND MOLOKAI AT SUNSET. SKIES OVER MAUI
WERE A LITTLE CLOUDIER ESPECIALLY OVER THE WEST MAUI MOUNTAINS AND
THE SLOPES SURROUNDING HALEAKALA. BY FAR BIG ISLAND IS THE
CLOUDIEST...COVERING BOTH WINDWARD AND LEEWARD. THE CLOUDS ON THE
KONA SIDE IS THE RESULT OF DAYTIME HEATING...LIGHT WIND...AMPLE
MOISTURE...AND AN SEMI UNSTABLE AIR MASS. SOME OF THESE CLOUDS
CONTAINED BRIEF HEAVY SHOWERS.

A CLUSTER OF DEEP CONVECTION IS NOTED IN THE TROPICS FAR SOUTHWEST
OF THE MAIN HAWAIIAN ISLANDS. THIS CLUSTER IS LOCATED ON THE NORTH
SIDE OF THE ITCZ BETWEEN 05N AND 10N FROM 160W TO 175W.

$$
LAU

000
FXHW60 PHFO 180147
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
347 PM HST FRI MAY 17 2013

.SYNOPSIS...
TRADE WINDS WILL WEAKEN STARTING TONIGHT AS A SERIES OF UPPER
LEVEL TROUGHS DIGS SOUTH OVER THE ISLANDS THIS WEEKEND. THE UPPER
TROUGHS WILL HELP TO INTENSIFY ANY SHOWERS THAT FORM OVER THE
ISLANDS FOR THE NEXT SEVERAL DAYS.

&&

.DISCUSSION...
AN UPPER LEVEL LOW IS SPINNING NEAR KAUAI AND OAHU LATE THIS
AFTERNOON. THIS UPPER LOW IS HELPING TO DESTABILIZE THE AIRMASS
AND ALLOW FOR SOME ENHANCEMENT TO BOTH INCOMING TRADE WIND
SHOWERS...AS WELL AS THE SHOWERS DEVELOPING DUE TO AFTERNOON SEA
BREEZES AND UPSLOPE FLOW.

THE UPPER LOW IS EXPECTED TO START MOVING AWAY TONIGHT...ONLY TO
BE REPLACED BY A SERIES OF FAIRLY STRONG UPPER TROUGHS DIGGING
DOWN FROM THE NORTH STARTING THIS WEEKEND. THIS WILL CONTINUE TO
DESTABILIZE THE AIRMASS IN THE LOW AND MID LEVELS OF THE
ATMOSPHERE AND ALLOW FOR ENHANCEMENT OF ANY SHOWER ACTIVITY THAT
OCCURS. THE UPPER TROUGH IS EXPECTED TO BE STRONG ENOUGH TO WEAKEN
THE LOW LEVEL FLOW BY SATURDAY. LAND AND SEA BREEZE CIRCULATIONS
WILL DOMINATE...MAINLY FOR THE ISLANDS FROM OAHU TO THE BIG
ISLAND. THUS...EXPECTING FAIRLY ACTIVE AFTERNOON CONVECTION OVER
THE ISLANDS BOTH SATURDAY AND SUNDAY...WITH PARTIAL CLEARING AT
NIGHT.

JUST AS THE WEEKEND UPPER TROUGH STARTS TO LIFT AWAY...STILL
ANOTHER TROUGH BEGINS TO APPROACH THE ISLANDS FROM THE NORTHWEST...
KEEPING THE LOW LEVEL FLOW LIGHT. THUS A CONTINUATION OF THE
DIURNAL CONVECTIVE WEATHER PATTERN WILL CONTINUE INTO NEXT WEEK.
THERE ARE SOME MINOR DIFFERENCES AMONG THE MODELS ABOUT HOW
UNSTABLE IT WILL BE AFTER SUNDAY.

IT APPEARS RIGHT NOW AS THOUGH THE MID LEVELS OF THE ATMOSPHERE
WILL STAY A LITTLE TOO WARM TO SUPPORT THUNDERSHOWERS...THOUGH IF
THESE WERE TO OCCUR THE BEST CHANCE WOULD BE OVER THE HIGHER
SLOPES OF THE BIG ISLAND EACH AFTERNOON THIS WEEKEND. IN OTHER
AREAS...LOCALIZED DOWNPOURS ARE POSSIBLE...PARTICULARLY IN THE
AFTERNOONS.

&&

.AVIATION...
AN UPPER LOW WILL SLIDE NORTH OF THE STATE TONIGHT AND SATURDAY...
INDUCING A TROUGH OVER THE ISLANDS AT THE SURFACE. THIS WILL BRING
DEEPER CLOUDS AND ENHANCED SHOWERS TONIGHT AND THROUGH THE
WEEKEND. TEMPO OR PREVAILING MVFR CIGS VIS AND MTN OBSC WILL BE
POSSIBLE DUE TO THESE CLOUDS AND SHOWERS OVER THE NEXT 48 HOURS.
AN AIRMET FOR MTN OBSC IS NOW IN EFFECT FOR THE WINDWARD AND
SOUTHEAST SIDE OF THE BIG ISLAND AND MAUI...AND OTHER PARTS OF
THE STATE MAY BE INCLUDED AT SOME POINT TONIGHT OR THIS WEEKEND.


&&

.MARINE...
A LATE MORNING ASCAT PASS CONTINUED TO SHOW A COUPLE 25 KNOTS AREAS
IN THE ALENUIHAHA CHANNEL AND NEAR SOUTH POINT. SUSTAINED WINDS AT
SURFACE LOCATIONS NEAR THESE AREAS SUGGEST WINDS HAVE REMAINED
ELEVATED TODAY. THE SMALL CRAFT ADVISORY CONTINUES FOR WINDIER
WATERS NEAR MAUI AND THE BIG ISLAND UNTIL 6 PM THIS EVENING. BARRING
ANY UPTICK IN WINDS...THE SMALL CRAFT ADVISORY WILL BE ALLOWED TO
EXPIRE AT 6 PM.

SURF REPORTS TODAY...COMBINED WITH THE LANAI BUOY READINGS SHOW THE
SOUTH SWELL HAS COME IN JUST A TOUCH HIGHER THAN ORIGINALLY
EXPECTED. WITH ANOTHER BUMP IN THE SOUTH SWELL EXPECTED TO ARRIVE
TONIGHT...THE SURF HEIGHTS WILL BE ADJUSTED UP A BIT FOR SOUTH
FACING SHORES TONIGHT THROUGH SATURDAY. EXPECT THE CURRENT SOUTH SWELL TO
PERSIST THROUGH THE WEEKEND AND SLOWLY DIMINISH NEXT WEEK.

A SMALL NORTHWEST SWELL IS EXPECT TO ARRIVE TOMORROW...AND PERSIST
THROUGH SUNDAY. ANOTHER COUPLE OF SMALL NORTHWEST SWELLS ARE
EXPECTED MONDAY AND WEDNESDAY.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 PM HST SUNDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-OAHU SOUTH SHORE-WAIANAE COAST-MOLOKAI-
LANAI MAKAI-KAHOOLAWE-MAUI LEEWARD WEST-MAUI CENTRAL VALLEY-
LEEWARD HALEAKALA-KONA-SOUTH BIG ISLAND-BIG ISLAND NORTH AND
EAST.

SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.


&&

$$
DISCUSSION...R BALLARD
MARINE.......M BALLARD
AVIATION.....FOSTER

000
ATHW40 PHFO 180025
SIMHI

HAWAIIAN ISLANDS SATELLITE INTERPRETATION MESSAGE
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
0030 UTC SAT MAY 18 2013

BASED ON DATA THROUGH 0000 UTC MAY 18 2013

AN UPPER LEVEL LOW REMAINS JUST EAST OF KAUAI THIS AFTERNOON AND
WATER VAPOR IMAGERY SHOWS THE LOW HAS DRIFTING TO THE NORTH OVER THE
LAST SEVERAL HOURS. THIN HIGH CLOUDS ARE SEEN MOVING TO THE
NORTHEAST ON THE EAST SIDE OF THE UPPER LEVEL LOW...AND MOVING TO
THE EAST SOUTH OF THE BIG ISLAND.

WATER VAPOR ALSO SHOWS AN UPPER LEVEL TROUGH DIGGING IN NORTH OF THE
ISLANDS. THE TROUGH AXIS IS ALONG A LINE FROM 42.6N 161.0W TO 30.0N
168.7W.

HIGH PRESSURE TO THE NORTHEAST OF THE ISLAND CONTINUES TO BRING LOW
CLOUDS INTO THE ISLANDS...HOWEVER LOW CLOUD MOVEMENT HAS SLOWED
SINCE DAYBREAK. AT 2 PM LOW CLOUDS ARE MOVING IN FROM THE EAST
BETWEEN 15 AND 20 MPH. LOW CLOUDS REMAIN CONCENTRATED EAST OF
156W...BETWEEN 18N AND 25N.

AT 2 PM...SCATTERED CLOUDS ARE FOUND ACROSS KAUAI AND NIIHAU...AND
OVER BOTH THE KOOLAU AND WAIANAE MOUNTAIN RANGES ON OAHU. SCATTERED
TO BROKEN CLOUDS ARE FOUND OVER HALAWA VALLEY ON MOLOKAI...WITH
ANOTHER LINE OF CLOUDS HAVING FORMED OVER THE LAST FEW HOURS OVER
THE SOUTH SHORE OF MOLOKAI KAWELA TO LAAU POINT. LOW CLOUDS HAVE
ALSO FOUND OVER THE SOUTHERN HALF OF LANAI THIS AFTERNOON. LOW
CLOUDS HAVE INCREASED OVER MAUI...WITH PLENTY OF CLOUDS FOUND OVER
THE EAST FACING SLOPES OF THE WEST MAUI MOUNTAINS THIS AFTERNOON.
CLOUDS COVER MOST OF THE HALEAKALA SLOPES...WITH THE CLOUDS
EXTENDING TO THE SOUTHWEST JUST BRUSHING THE EASTERN SHORES OF
KAHOOLAWE AT 2 PM. CLOUDS HAVE ALSO INCREASED OVER THE BIG ISLAND
SINCE DAYBREAK...WITH CLOUDS COVERING MOST OF THE ISLAND THIS
AFTERNOON UP TO 11000 FEET. THE AREAS WITH THE FEWEST CLOUDS
OVERHEAD INCLUDE THE AREA BETWEEN MAHUKONA TO UPOLU POINT ON THE
NORTHERN TIP OF THE BIG ISLAND...THE AREA NEAR SADDLE ROAD JUNCTION
AND THE LOWER SLOPES NEAR THE KONA VILLAGE RESORT AND KEAHOLE POINT.

$$

000
FXHW60 PHFO 171956
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
955 AM HST FRI MAY 17 2013

.SYNOPSIS...
A HIGH NORTHEAST OF THE AREA WILL MAINTAIN LOCALLY BREEZY TRADE
WINDS TODAY. THE TRADES WILL FOCUS SHOWERS OVER MAINLY WINDWARD
AREAS. A TROUGH APPROACHING FROM THE NORTHWEST WILL RAPIDLY WEAKEN
THE WINDS STARTING TOMORROW. MOISTURE AND INSTABILITY ASSOCIATED
WITH THE TROUGH WILL BRING UNSETTLED WEATHER THROUGH MOST OF NEXT
WEEK.

&&

.DISCUSSION...
WE UPDATED THE GRIDS EARLIER TO ADJUST POPS OVER MAINLY LEEWARD
AREAS. NO OTHER CHANGES ANTICIPATED TO THE SHORT TERM PORTION OF THE
FORECAST AT THIS TIME. THE SERIES OF UPPER TROUGHS IN OUR VICINITY
WILL CONTINUE TO PROVIDE SOME ENHANCEMENT TO LOCAL SHOWERS THIS
WEEKEND...BUT THERE ARE SOME TOUGH QUESTIONS TO ANSWER AS TO THE
PLACEMENT AND TIMING OF ANY HEAVIER SHOWERS BASED ON THE AMOUNT AND
LOCATION OF THE FORCING PROVIDED BY LOW LEVEL SYNOPTIC FLOW OR
MESOSCALE ISLAND CIRCULATIONS. WILL LIKELY BE MAKING SOME
ADJUSTMENTS TO THE WEEKEND TIME FRAME AND BEYOND AFTER WE STUDY THE
17/12Z ECMWF SOLUTION AND UPDATED MULTI-MODEL ENSEMBLE SOLUTION.

&&

.PREV DISCUSSION...
A SFC HIGH PRESSURE REMAINS CENTERED NE OF THE ALOHA STATE AND
KEEPING A TRADE WIND WEATHER REGIME ACROSS THE AREA THROUGH THE NEXT
COUPLE OF DAYS. THE TRADES REMAIN MODERATE TO LOCALLY BREEZY WITH
SHOWERS FAVORING WINDWARD AND MAUKA AREAS. SOME OF THE LARGER
SHOWERS WILL BE PUSHED OVER THE MOUNTAIN RANGES AND INTO LEEWARD
AREAS AT TIMES...ESPECIALLY AT NIGHT.

AN UPPER LVL LOW LINGERING OVER THE ISLAND CHAIN WILL KEEP ENHANCED
SHOWER ACTIVITY TODAY AND THROUGH EARLY SAT...THEN QUICKLY PUSH E
AS A DEEPENING UPPER TROUGH MOVES ACROSS THE N CPAC DURING THE
WEEKEND. MODELS STILL SHOW FAIR AGREEMENT REGARDING THE OVERALL
SOLUTION FOR THIS TROUGH...WHICH DIGS FURTHER S TOWARDS THE ISLAND
CHAIN AND DESTABILIZES THE AIRMASS BY BRINGING COLDER TEMPS ALOFT
AND INCREASING DEEP MOISTURE. AT THE LOW LVLS...A SFC TROUGH
REFLECTION SEEMS TO DEVELOP ACROSS THE ISLANDS. WITH THIS SYNOPTIC
SETUP IN PLACE IT IS POSSIBLE THAT A HYBRID WIND REGIME WILL
ESTABLISH...WITH LIGHT SE FLOW OVER WINDWARD AREAS OF THE BIG ISLAND
AND MAUI...AND A WEAK NE FLOW OVER THE W HALF OF THE ISLAND CHAIN.
IF THIS PATTERN MATERIALIZES...EXPECT WINDS TO BECOME WEAK...
ESPECIALLY OVER OAHU AND MAUI COUNTY...ALLOWING FOR SEA BREEZES TO
DEVELOP EACH DAY FROM SUN THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
SHOWERS WILL BECOME MORE WIDESPREAD ACROSS THE ISLANDS WITH HIGHER
CHANCES OF RAIN OVER INTERIOR AND MOUNTAIN AREAS.

THE WEAK SE FLOW AROUND THE BIG ISLAND NEXT WEEK MAY COMBINE WITH
THE LIGHT WINDS ELSEWHERE AND BRING WIDESPREAD VOG ACROSS THE
SMALLER ISLANDS...WHICH SHOULD ALSO REMAIN IN PLACE THROUGH AT LEAST
THE MIDDLE OF NEXT WEEK.

&&

.MARINE...
THE FRESH TRADE WINDS ARE EXPECTED TO CONTINUE TODAY. THEREFORE...
THE SMALL CRAFT ADVISORY FOR WINDIER WATERS NEAR MAUI AND THE BIG
ISLAND WILL BE EXTENDED UNTIL 6 PM HST THIS EVENING. CONDITIONS
SHOULD DROP TO BELOW ADVISORY LEVELS LATER TONIGHT.

BUOYS SO FAR ARE RUNNING RIGHT ABOUT...OR JUST SLIGHTLY OVER...WHAT
WAS EXPECTED. WILL NOT MAKE ANY CHANGES TO FORECAST SURF HEIGHTS AT
THIS POINT.

&&

.AVIATION...
VFR COND WILL PREVAIL ACROSS THE ISLAND CHAIN TODAY. BRIEF MVFR CIGS
AND MTN OBSC ALONG THE WINDWARD SIDES OF THE ISLANDS DUE TO PASSING
LOW CLOUDS AND SHRA.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 600 PM HST THIS EVENING FOR THE PAILOLO
AND ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF THE BIG
ISLAND.

HIGH SURF ADVISORY FOR SOUTH FACING SHORES OF ALL ISLANDS THROUGH
THE WEEKEND.

&&

$$

DISCUSSION...R BALLARD
AVIATION...FOSTER

000
FXHW60 PHFO 171836 AAA
AFDHFO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HONOLULU HI
830 AM HST FRI MAY 17 2013

.UPDATE...
WE HAVE UPDATED THE GRIDS AND TEXT FORECASTS TO DECREASE THE CHANCE
OF SHOWERS TODAY...MAINLY OVER LEEWARD AREAS.

&&

.SYNOPSIS...
A HIGH NORTHEAST OF THE AREA WILL MAINTAIN LOCALLY BREEZY TRADE
WINDS TODAY. THE TRADES WILL FOCUS SHOWERS OVER MAINLY WINDWARD
AREAS. A TROUGH APPROACHING FROM THE NORTHWEST WILL RAPIDLY WEAKEN
THE WINDS STARTING TOMORROW. MOISTURE AND INSTABILITY ASSOCIATED
WITH THE TROUGH WILL BRING UNSETTLED WEATHER THROUGH MOST OF NEXT
WEEK.

&&

.DISCUSSION...
A SFC HIGH PRESSURE REMAINS CENTERED NE OF THE ALOHA STATE AND
KEEPING A TRADE WIND WEATHER REGIME ACROSS THE AREA THROUGH THE NEXT
COUPLE OF DAYS. THE TRADES REMAIN MODERATE TO LOCALLY BREEZY WITH
SHOWERS FAVORING WINDWARD AND MAUKA AREAS. SOME OF THE LARGER
SHOWERS WILL BE PUSHED OVER THE MOUNTAIN RANGES AND INTO LEEWARD
AREAS AT TIMES...ESPECIALLY AT NIGHT.

AN UPPER LVL LOW LINGERING OVER THE ISLAND CHAIN WILL KEEP ENHANCED
SHOWER ACTIVITY TODAY AND THROUGH EARLY SAT...THEN QUICKLY PUSH E
AS A DEEPENING UPPER TROUGH MOVES ACROSS THE N CPAC DURING THE
WEEKEND. MODELS STILL SHOW FAIR AGREEMENT REGARDING THE OVERALL
SOLUTION FOR THIS TROUGH...WHICH DIGS FURTHER S TOWARDS THE ISLAND
CHAIN AND DESTABILIZES THE AIRMASS BY BRINGING COLDER TEMPS ALOFT
AND INCREASING DEEP MOISTURE. AT THE LOW LVLS...A SFC TROUGH
REFLECTION SEEMS TO DEVELOP ACROSS THE ISLANDS. WITH THIS SYNOPTIC
SETUP IN PLACE IT IS POSSIBLE THAT A HYBRID WIND REGIME WILL
ESTABLISH...WITH LIGHT SE FLOW OVER WINDWARD AREAS OF THE BIG ISLAND
AND MAUI...AND A WEAK NE FLOW OVER THE W HALF OF THE ISLAND CHAIN.
IF THIS PATTERN MATERIALIZES...EXPECT WINDS TO BECOME
WEAK...ESPECIALLY OVER OAHU AND MAUI COUNTY...ALLOWING FOR SEA
BREEZES TO DEVELOP EACH DAY FROM SUN THROUGH AT LEAST THE MIDDLE OF
NEXT WEEK. SHOWERS WILL BECOME MORE WIDESPREAD ACROSS THE ISLANDS
WITH HIGHER CHANCES OF RAIN OVER INTERIOR AND MOUNTAIN AREAS.

THE WEAK SE FLOW AROUND THE BIG ISLAND NEXT WEEK MAY COMBINE WITH
THE LIGHT WINDS ELSEWHERE AND BRING WIDESPREAD VOG ACROSS THE
SMALLER ISLANDS...WHICH SHOULD ALSO REMAIN IN PLACE THROUGH AT LEAST
THE MIDDLE OF NEXT WEEK.

&&

.MARINE...
THE FRESH TRADE WINDS ARE EXPECTED TO CONTINUE TODAY. THEREFORE...
THE SMALL CRAFT ADVISORY FOR WINDIER WATERS NEAR MAUI AND THE BIG
ISLAND WILL BE EXTENDED UNTIL 6 PM HST THIS EVENING. CONDITIONS
SHOULD DROP TO BELOW ADVISORY LEVELS LATER TONIGHT.

LARGE SOUTH SWELLS WILL CONTINUE TO REACH THE ISLANDS DURING THE
NEXT COUPLE OF DAYS FOR WHICH A HIGH SURF ADVISORY REMAINS IN EFFECT
THROUGH THE WEEKEND.

&&

.AVIATION...
A BROADER AREA OF LOW CLOUDS RIDING ON THE TRADE WINDS WILL AFFECT
THE ISLANDS TODAY...BRINGING SOME SHOWERS. VFR CONDITIONS SHOULD
PREVAIL FOR ALL TERMINALS...THOUGH WINDWARD SITES MAY EXPERIENCE
BRIEF MVFR CEILING CONDITIONS DUE TO PASSING LOW CLOUDS AND SHOWERS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 600 PM HST THIS EVENING FOR THE PAILOLO
AND ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF THE BIG
ISLAND.

HIGH SURF ADVISORY FOR SOUTH FACING SHORES OF ALL ISLANDS THROUGH
THE WEEKEND.

&&

$$

UPDATE...DONALDSON
DISCUSSION/MARINE...REYNES
AVIATION...HUI

000
ATHW40 PHFO 171829
SIMHI

HAWAIIAN ISLANDS SATELLITE INTERPRETATION MESSAGE
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
1830 UTC FRI MAY 17 2013

BASED ON DATA THROUGH 1800 UTC MAY 17 2013

WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW JUST EAST OF KAUAI THIS
MORNING. HIGH CLOUDS HAVE BEEN MOVING OVER THE MAUI AND THE BIG
ISLAND FROM THE SOUTHWEST IN THE UPPER LEVEL WIND FLOW ON THE EAST
SIDE OF THIS LOW.

HIGH PRESSURE TO THE NORTHEAST OF THE ISLANDS CONTINUES TO BRING LOW
LEVEL CLOUDS TO THE ISLANDS FROM THE EAST BETWEEN 20 AND 25 MPH. THE
HIGHEST CONCENTRATION OF LOW CLOUDS ARE FOUND EAST OF 155W AND SOUTH
OF 24N.

LOW CLOUDS ARE CONCENTRATED OVER THE WINDWARD SIDES OF THE ISLANDS
THIS MORNING. ON KAUAI...LOW CLOUDS ARE FOUND OVER THE EASTERN
TWO-THIRDS OF THE ISLAND...WITH NIIHAU BEING CLOUD FREE. ON
OAHU...CLOUDS ARE FOUND OVER THE KOOLAU RANGE AND THE ADJACENT
COASTAL AREAS. MOLOKAI HAS LOW CLOUDS OVER THE HALAWA VALLEY ON THE
EASTERN END OF THE ISLAND...WHILE LANAI AND KAHOOLAWE HAVE JUST A
FEW CLOUDS OVER THE INTERIOR OF THE ISLAND. ON MAUI...LOW CLOUDS ARE
FOUND OVER THE EAST FACING SLOPES OF THE WEST MAUI MOUNTAINS...AND
OVER THE EAST FACING SLOPES OF HALEAKALA FROM HUELO TO HANA TO
KAUPO.

THE BIG ISLAND HAS LOW CLOUDS OVER THE EAST FACING SLOPES OF THE
KOHALA MOUNTAINS...AND LOW CLOUDS COVERING MOST OF THE NORTH
HILO...SOUTH HILO AND PUNA DISTRICTS. THESE CLOUDS ARE SPILLING INTO
THE EASTERN PORTION OF THE KAU DISTRICT.

$$

000
FXHW60 PHFO 171334
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 AM HST FRI MAY 17 2013

.SYNOPSIS...
THE TRADES WILL REMAIN MODERATE TO LOCALLY BREEZY TODAY AND THROUGH
SATURDAY WITH SHOWERS FAVORING WINDWARD AND MOUNTAIN AREAS. SOME OF
THE LARGER SHOWERS WILL REACH LEEWARD LOCATIONS AT TIMES. A TROUGH
WILL APPROACH THE ISLANDS ON SATURDAY...BRINGING A WEAKENING OF THE
TRADES. THIS WILL ALLOW FOR INCREASING MOISTURE AND SHOWER ACTIVITY
ACROSS THE ISLANDS AS SEA BREEZES DEVELOP EACH DAY FROM SUNDAY AND
THROUGH MUCH OF NEXT WEEK.

&&

.DISCUSSION...
A SFC HIGH PRESSURE REMAINS CENTERED NE OF THE ALOHA STATE AND
KEEPING A TRADE WIND WEATHER REGIME ACROSS THE AREA THROUGH THE NEXT
COUPLE OF DAYS. THE TRADES REMAIN MODERATE TO LOCALLY BREEZY WITH
SHOWERS FAVORING WINDWARD AND MAUKA AREAS. SOME OF THE LARGER
SHOWERS WILL BE PUSHED OVER THE MOUNTAIN RANGES AND INTO LEEWARD
AREAS AT TIMES...ESPECIALLY AT NIGHT.

AN UPPER LVL LOW LINGERING OVER THE ISLAND CHAIN WILL KEEP ENHANCED
SHOWER ACTIVITY TODAY AND THROUGH EARLY SAT...THEN QUICKLY PUSH E
AS A DEEPENING UPPER TROUGH MOVES ACROSS THE N CPAC DURING THE
WEEKEND. MODELS STILL SHOW FAIR AGREEMENT REGARDING THE OVERALL
SOLUTION FOR THIS TROUGH...WHICH DIGS FURTHER S TOWARDS THE ISLAND
CHAIN AND DESTABILIZES THE AIRMASS BY BRINGING COLDER TEMPS ALOFT
AND INCREASING DEEP MOISTURE. AT THE LOW LVLS...A SFC TROUGH
REFLECTION SEEMS TO DEVELOP ACROSS THE ISLANDS. WITH THIS SYNOPTIC
SETUP IN PLACE IT IS POSSIBLE THAT A HYBRID WIND REGIME WILL
ESTABLISH...WITH LIGHT SE FLOW OVER WINDWARD AREAS OF THE BIG ISLAND
AND MAUI...AND A WEAK NE FLOW OVER THE W HALF OF THE ISLAND CHAIN.
IF THIS PATTERN MATERIALIZES...EXPECT WINDS TO BECOME
WEAK...ESPECIALLY OVER OAHU AND MAUI COUNTY...ALLOWING FOR SEA
BREEZES TO DEVELOP EACH DAY FROM SUN THROUGH AT LEAST THE MIDDLE OF
NEXT WEEK. SHOWERS WILL BECOME MORE WIDESPREAD ACROSS THE ISLANDS
WITH HIGHER CHANCES OF RAIN OVER INTERIOR AND MOUNTAIN AREAS.

THE WEAK SE FLOW AROUND THE BIG ISLAND NEXT WEEK MAY COMBINE WITH
THE LIGHT WINDS ELSEWHERE AND BRING WIDESPREAD VOG ACROSS THE
SMALLER ISLANDS...WHICH SHOULD ALSO REMAIN IN PLACE THROUGH AT LEAST
THE MIDDLE OF NEXT WEEK.

&&

.MARINE...
THE FRESH TRADE WINDS ARE EXPECTED TO CONTINUE TODAY. THEREFORE...
THE SMALL CRAFT ADVISORY FOR WINDIER WATERS NEAR MAUI AND THE BIG
ISLAND WILL BE EXTENDED UNTIL 6 PM HST THIS EVENING. CONDITIONS
SHOULD DROP TO BELOW ADVISORY LEVELS LATER TONIGHT.

LARGE SOUTH SWELLS WILL CONTINUE TO REACH THE ISLANDS DURING THE
NEXT COUPLE OF DAYS FOR WHICH A HIGH SURF ADVISORY REMAINS IN EFFECT
THROUGH THE WEEKEND.

&&

.AVIATION...
A BROADER AREA OF LOW CLOUDS RIDING ON THE TRADE WINDS WILL AFFECT
THE ISLANDS TODAY...BRINGING SOME SHOWERS. VFR CONDITIONS SHOULD
PREVAIL FOR ALL TERMINALS...THOUGH WINDWARD SITES MAY EXPERIENCE
BRIEF MVFR CEILING CONDITIONS DUE TO PASSING LOW CLOUDS AND SHOWERS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 600 PM HST THIS EVENING FOR THE PAILOLO
AND ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF THE BIG
ISLAND.

HIGH SURF ADVISORY FOR SOUTH FACING SHORES OF ALL ISLANDS THROUGH
THE WEEKEND.

&&

$$

DISCUSSION/MARINE...REYNES
AVIATION...HUI

000
ATHW40 PHFO 171230
SIMHI

HAWAIIAN ISLANDS SATELLITE INTERPRETATION MESSAGE
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
1230 UTC FRI MAY 17 2013

BASED ON DATA THROUGH 1200 UTC MAY 17 2013

HIGH PRESSURE IS PROPELLING SCATTERED TO BROKEN LOW CLOUDS
WESTWARD...ACROSS THE CENTRAL PACIFIC FROM 10N TO 20N. THESE LOW
CLOUDS ARE LOW TOPPED NEAR 4 THOUSAND FEET AS THEY EXIT THE EAST
PACIFIC...AND INCREASE IN HEIGHT AS THEY MOVE ACROSS THE CENTRAL
PACIFIC...WITH CLOUD TOPS REACHING 15 THOUSAND FEET NEAR THE
DATELINE. CLOUD GROWTH IS MAINLY DUE TO MOISTURE FLUX FROM THE OCEAN
SURFACE.

BETWEEN 20N AND 30N...THE WESTWARD FLOW OF LOW CLOUDS IS
INTERRUPTED BY A N-S TROUGH ALONG 160W...DUE NORTH OF KAUAI. THE
TROUGH AREA IS DEPICTED BY A LOW-LEVEL SWIRL IN THE CLOUD FIELD
WITH A SHIELD OF CLOUDS EXTENDING NORTH OF 30N. EAST OF THE TROUGH
LOW CLOUDS ARE BEING PULLED TO THE NORTH...AND WEST OF THE TROUGH
OVERCAST LOW CLOUDS EXTEND TO 175W AND ARE FAIRLY STATIONARY.

WATER VAPOR IMAGERY SHOW AN UPPER LEVEL LOW CENTERED OVER KAUAI
WITH HIGH CIRRUS CLOUDS ALONG THE SOUTHERN PERIPHERY OF THE
CIRCULATION MOVING OVER THE BIG ISLAND AND MAUI. NO LOW CLOUD
ENHANCEMENT FROM THE UPPER LOW IS SEEN AT THIS TIME.

OVER HAWAII...TRADE WINDS ARE PUSHING LOW CLOUDS INTO THE WINDWARD
SLOPES PROVIDING OVERCAST SKIES AND LIMITED SHOWERS. SATELLITE
PRECIPITABLE WATER ESTIMATES SHOW A PALTRY 1 INCH OF PW OVER THE
STATE AND SIMILAR VALUES UPSTREAM OF THE ISLANDS. LEEWARD LOCATIONS
ARE MOSTLY CLEAR OVER THE SMALLER ISLANDS...WHILE ON THE BIG ISLAND
SKIES HAVE GRADUAL CLEARED THROUGH THE NIGHT. LOW LEVEL CONVERGENCE
WEST OF THE BIG ISLAND EXTENDS A PLUME OF OVERCAST LOW CLOUDS 400
MILES LEE OF THE ORCHID ISLE.

$$

MORRISON

000
FXHW60 PHFO 170630
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST THU MAY 16 2013

.SYNOPSIS...
MODERATE TO LOCALLY BREEZY TRADES WILL CONTINUE THROUGH SATURDAY.
SHOWERS WILL FAVOR WINDWARD AND MOUNTAIN AREAS...WITH SOME OF THE
LARGER SHOWERS REACHING LEEWARD LOCATIONS AT TIMES. A TROUGH WILL
APPROACH THE ISLANDS ON SATURDAY...BRINGING A WEAKENING OF THE
TRADES. THIS WILL ALLOW FOR INCREASING MOISTURE AND SHOWER ACTIVITY
ACROSS THE AREA AS SEA AND LAND BREEZES DEVELOP EACH DAY FROM SUNDAY
AND THROUGH MUCH OF NEXT WEEK.

&&

.DISCUSSION...
SFC HIGH PRESSURE NE OF THE STATE STILL DOMINATES THE AREA...KEEPING
A TRADE WIND WEATHER REGIME IN PLACE THROUGH THE NEXT COUPLE OF
DAYS. THE TRADES OVER THE ISLANDS WILL REMAIN MODERATE TO LOCALLY
BREEZY AT TIMES. SHOWERS WILL CONTINUE TO FAVOR WINDWARD AND MAUKA
AREAS...WITH SOME OF THE LARGER SHOWERS REACHING LEEWARD LOCATIONS
AT TIMES...ESPECIALLY AT NIGHT.

THERE IS STILL SOME SHOWER ACTIVITY ENHANCEMENT DUE TO AN UPPER LVL
LOW RIGHT ABOVE THE ISLANDS. THIS FEATURE LINGERS THROUGH FRI...THEN
PUSHES E AS A LONG WAVE UPPER TROUGH MOVES ACROSS THE N CPAC AND
DIGS FURTHER S TOWARDS THE ISLANDS ON SAT.

GLOBAL MODELS REMAIN IN FAIR AGREEMENT REGARDING THE EVOLUTION OF
THE AFOREMENTIONED UPPER TROUGH DURING THE WEEKEND AND INTO EARLY
NEXT WEEK. THE TROUGH IS EXPECTED TO AMPLIFY AND REACH S TOWARDS
THE MAIN HAWAIIAN ISLANDS...DESTABILIZING THE AIRMASS BY BRINGING
COOLER TEMPS ALOFT AND INCREASING DEEP MOISTURE. LATEST MODEL
SOLUTIONS SUGGEST A LOW LVL REFLEXION WITH A SFC TROUGH DEVELOPING
ACROSS THE ISLANDS. THIS WILL BRING A BLOCKING PATTERN OF THE
TRADES AND POSSIBLY ESTABLISHING A HYBRID WIND REGIME WITH LIGHT SE
FLOW OVER WINDWARD AREAS OF THE BIG ISLAND AND MAUI...AND A WEAK NE
FLOW OVER THE W HALF OF THE ISLAND CHAIN.

IF THE SFC TROUGH MATERIALIZES...IT WILL WEAKEN THE WINDS...
ESPECIALLY OVER OAHU AND MAUI COUNTY. THIS WILL ALLOW FOR SEA AND
LAND BREEZE CIRCULATIONS TO DEVELOP EACH DAY FROM SUN THROUGH AT
LAST THE MIDDLE OF NEXT WEEK. THIS SYNOPTIC SCENARIO WILL SUPPORT
WIDESPREAD SHOWER ACTIVITY ACROSS THE ISLANDS...WITH HIGHER CHANCES
OF RAIN OVER INTERIOR AND MOUNTAIN AREAS.

THE EXPECTED SE FLOW AROUND THE BIG ISLAND NEXT WEEK MAY COMBINE
WITH THE LIGHT WINDS ELSEWHERE IN ORDER TO BRING WIDESPREAD VOG
ACROSS THE SMALLER ISLANDS...WHICH SHOULD ALSO REMAIN IN PLACE
THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
DAYS.

&&

.MARINE...
MODERATE TO FRESH TRADE WINDS WILL CONTINUE THROUGH FRI...KEEPING
SMALL CRAFT ADVISORY OVER WINDIER WATERS NEAR MAUI AND THE BIG
ISLAND. CONDITIONS SHOULD DROP TO BELOW ADVISORY LEVELS BY FRI LATE
MORNING.

LARGE SOUTH SWELLS WILL CONTINUE TO REACH THE ISLANDS DURING THE
NEXT COUPLE OF DAYS FOR WHICH A HIGH SURF ADVISORY REMAINS IN EFFECT
THROUGH EARLY SAT MORNING. THIS ADVISORY MAY BE EXTENDED IF
NECESSARY.

&&

.AVIATION...
BATCHES OF LOW CLOUDS RIDING ON THE TRADE WINDS WILL AFFECT THE
ISLANDS THROUGH REST OF THE EVENING INTO EARLY FRIDAY...BRINGING
SOME SHOWERS. VFR CONDITIONS SHOULD PREVAIL FOR ALL
TERMINALS...THOUGH WINDWARD SITES MAY EXPERIENCE BRIEF MVFR CEILING
CONDITIONS DUE TO PASSING LOW CLOUDS.

TRADE WINDS HAVE EASED OVER THE STATE. THEREFORE AIRMET TANGO HAS
BEEN DROPPED. WINDS MAY PICK UP A BIT BY FRIDAY AFTERNOON ONCE AGAIN
AND MAY REQUIRE THE ISSUANCE OF AIRMET TANGO.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 600 AM HST FRIDAY FOR THE PAILOLO AND
ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF THE BIG
ISLAND.

HIGH SURF ADVISORY FOR SOUTH FACING SHORES OF ALL ISLANDS UNTIL 600
AM HST SATURDAY.

&&

$$

DISCUSSION/MARINE...REYNES
AVIATION...HUI

000
ATHW40 PHFO 170536
SIMHI

HAWAIIAN ISLANDS SATELLITE INTERPRETATION MESSAGE
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
0530 UTC FRI MAY 17 2013

BASED ON DATA THROUGH 0500 UTC MAY 17 2013

HIGH PRESSURE IS PROPELLING SCATTERED TO BROKEN LOW CLOUDS
WESTWARD...ACROSS THE CENTRAL PACIFIC FROM 10N TO 20N. THESE LOW
CLOUDS ARE LOW TOPPED NEAR 4 THOUSAND FEET AS THEY EXIT THE EAST
PACIFIC...AND INCREASE IN HEIGHT AS THEY MOVE ACROSS THE CENTRAL
PACIFIC...WITH CLOUD TOPS REACHING 15 THOUSAND FEET NEAR THE
DATELINE. CLOUD GROWTH IS MAINLY DUE TO MOISTURE FLUX FROM THE OCEAN
SURFACE.

BETWEEN 20N AND 30N...THE WESTWARD FLOW OF LOW CLOUDS IS
INTERRUPTED BY A N-S TROUGH ALONG 160W...DUE NORTH OF KAUAI. THE
TROUGH AREA IS DEPICTED BY A LOW-LEVEL SWIRL IN THE CLOUD FIELD
WITH A SHIELD OF CLOUDS EXTENDING NORTH OF 30N. EAST OF THE TROUGH
LOW CLOUDS ARE BEING PULLED TO THE NORTH...AND WEST OF THE TROUGH
OVERCAST LOW CLOUDS ARE MOVING EAST AT 10 MPH.

WATER VAPOR IMAGERY SHOW AN UPPER LEVEL LOW CENTERED OVER KAUAI
WITH HIGH CIRRUS CLOUDS ALONG THE SOUTHERN PERIPHERY OF THE
CIRCULATION MOVING OVER THE BIG ISLAND. A BRIEF THUNDERSTORM POPPED
UP 200 MILES SOUTHWEST OF KAUAI THIS AFTERNOON DUE TO THE INFLUENCE
OF THE UPPER LOW...BUT HAS SINCE DISSIPATED. NO OTHER LOW CLOUD
ENHANCEMENT FROM THE UPPER LOW IS SEEN AT THIS TIME.

OVER HAWAII...TRADE WINDS ARE PUSHING LOW CLOUDS INTO THE WINDWARD
SLOPES PROVIDING OVERCAST SKIES AND LIMITED SHOWERS. SATELLITE
PRECIPITABLE WATER ESTIMATES SHOW A PALTRY 1 INCH OF PW OVER THE
STATE AND SIMILAR VALUES UPSTREAM OF THE ISLANDS. LEEWARD LOCATIONS
ARE MOSTLY CLEAR OVER THE SMALLER ISLANDS...WHILE ON THE BIG ISLAND
AFTERNOON SEA BREEZES BROUGHT IN OVERCAST SKIES. LOW LEVEL
CONVERGENCE WEST OF THE BIG ISLAND EXTENDS A PLUME OF OVERCAST LOW
CLOUDS 400 MILES LEE OF THE ORCHID ISLE.


$$

MORRISON

000
FXHW60 PHFO 170146
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST THU MAY 16 2013


.SYNOPSIS...
A SURFACE HIGH NORTHEAST OF THE AREA WILL SUPPORT LOCALLY BREEZY
TRADE WINDS THROUGH TOMORROW. CLOUDS CARRIED BY THE TRADES WILL
PRODUCE SOME SHOWERS...MAINLY OVER WINDWARD AREAS. A TROUGH ALOFT
WILL DIG DOWN OVER ISLANDS DURING THE WEEKEND. THIS TROUGH WILL
LIKELY BRING MUGGY...HAZY WEATHER WITH CLOUDS AND SHOWERS MOST
ACTIVE DURING THE AFTERNOONS AND EVENINGS. TYPICAL SPRINGTIME
TRADE-WIND WEATHER IS NOT EXPECTED TO RETURN TILL LATE NEXT WEEK. A
SERIES OF SWELLS WILL KEEP SURF ELEVATED ALONG SOUTH SHORES THROUGH
EARLY NEXT WEEK.
&&

.DISCUSSION...
SURFACE ANALYSES SHOW A 1026 MB SURFACE HIGH CENTERED ABOUT 925
MILES NORTHEAST OF THE MAIN HAWAIIAN ISLANDS NEAR 31N 146W. THE
PRESSURE GRADIENT SOUTHWEST OF THE HIGH HAS BEEN MAINTAINING LOCALLY
BREEZY TRADE WINDS OVER THE ISLANDS. THE TRADES HAVE BEEN PUSHING
SCATTERED SHOWERS OVER WINDWARD AREAS. A LOW ALOFT JUST SOUTH OF
KAUAI HAS BEEN MAKING THE ATMOSPHERE A BIT UNSTABLE NEAR KAUAI. THE
200 PM SOUNDING FROM LIHUE SHOWED A LIFTED INDEX...LI...OF -2.4
WHILE THE LI WAS 2.6 AT HILO. BREEZY TRADE WINDS AND SCATTERED
WINDWARD SHOWERS WILL PERSIST THROUGH TOMORROW.

THE GLOBAL MODELS ARE IN GOOD AGREEMENT OVER THE NEXT SEVERAL DAYS.
THE MODELS SHOW A TROUGH ALOFT DIGGING OVER THE ISLANDS FROM THE
NORTHWEST OVER THE WEEKEND. THE TROUGH ALOFT WILL DESTABILIZE THE
ATMOSPHERE AND INDUCE A SURFACE TROUGH OVER THE ISLANDS WITH
SOUTHEAST FLOW NEAR THE BIG ISLAND AND NORTHEAST FLOW NEAR KAUAI.
THE SURFACE TROUGH WILL BRING MUCH WEAKER SURFACE WINDS...ESPECIALLY
OVER OAHU AND MAUI COUNTY. THE PREVAILING FLOW WILL BE LIGHT ENOUGH
FOR NIGHTTIME LAND BREEZES AND DAYTIME SEA BREEZES TO PREVAIL
STARTING SATURDAY AFTERNOON AND CONTINUING THROUGH MOST OF NEXT
WEEK. THE ATMOSPHERE WILL BE UNSTABLE ENOUGH FOR AFTERNOON SHOWERS
OVER INTERIOR AREAS. WITH SOUTHEAST FLOW NEAR THE BIG ISLAND AND
LIGHT WINDS ELSEWHERE...VOG WILL BE WIDESPREAD NEXT WEEK. THE
COMPUTER MODELS SUGGEST TRADE WINDS MAY START TO RETURN IN 8 OR 9
DAYS.

&&

.MARINE...
FRESH TRADES WILL CONTINUE THROUGH TOMORROW WITH SMALL CRAFT
ADVISORY CONDITIONS CONTINUING FOR THE WINDIER WATERS NEAR MAUI AND
THE BIG ISLAND. THE WINDS ARE DOWN A BIT AND WE HAVE DROPPED THE
SCA FOR THE KAIWI CHANNEL. THE WINDS SHOULD EASE BELOW ADVISORY
LEVELS TOMORROW.

A SERIES OF LARGE SOUTH SWELLS WILL AFFECT THE ISLANDS IN THE NEXT
FEW OF DAYS. THE FIRST OF THESE SWELLS CAME IN A BIT LATE...BUT
THE SWELL HAS COME UP AT THE BUOYS SOUTH OF THE ISLANDS AND THIS
SWELL WILL BE BRINGING ADVISORY LEVEL SURF TO ALL ISLANDS. A HIGH
SURF ADVISORY IS UP THROUGH EARLY SATURDAY MORNING AND MAY NEED TO
BE EXTENDED.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT THE HAWAII TERMINALS TONIGHT.

AIRMET TANGO FOR LOW LVL TURB BELOW 080 SOUTHWEST OF THE MOUNTAINS
DUE TO THE BREEZY TRADE WINDS WILL LIKELY BE DROPPED THIS EVENING.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 600 AM HST FRIDAY FOR THE PAILOLO AND
ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF THE BIG
ISLAND.

HIGH SURF ADVISORY FOR SOUTH FACING SHORES OF ALL ISLANDS UNTIL 600
AM HST SATURDAY.

&&

$$
DONALDSON

000
FXHW60 PHFO 162011
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST THU MAY 16 2013

.SYNOPSIS...
A SURFACE HIGH NORTHEAST OF THE AREA WILL SUPPORT LOCALLY BREEZY
TRADE WINDS THROUGH TOMORROW. CLOUDS CARRIED BY THE TRADES WILL
PRODUCE SOME SHOWERS...MAINLY OVER WINDWARD AREAS. A TROUGH ALOFT
WILL DIG DOWN OVER ISLANDS DURING THE WEEKEND. THIS TROUGH WILL
LIKELY BRING MUGGY...HAZY WEATHER WITH CLOUDS AND SHOWERS MOST
ACTIVE DURING THE AFTERNOONS AND EVENINGS. TYPICAL SPRINGTIME
TRADE-WIND WEATHER IS NOT EXPECTED TO RETURN TILL LATE NEXT WEEK. A
SERIES OF SWELLS WILL KEEP SURF ELEVATED ALONG SOUTH SHORES THROUGH
EARLY NEXT WEEK.

&&

.DISCUSSION...
SURFACE ANALYSES SHOW A 1028 MB SURFACE HIGH CENTERED ABOUT 950
MILES NORTHEAST OF THE MAIN HAWAIIAN ISLANDS NEAR 31N 146W. THE
PRESSURE GRADIENT SOUTHWEST OF THE HIGH HAS BEEN MAINTAINING LOCALLY
BREEZY TRADE WINDS OVER THE ISLANDS. THE TRADES HAVE BEEN PUSHING
SCATTERED SHOWERS OVER WINDWARD AREAS. A LOW ALOFT JUST SOUTH OF
KAUAI HAS BEEN MAKING THE ATMOSPHERE A BIT UNSTABLE...THE 200 AM
SOUNDING FROM LIHUE SHOWED A LIFTED INDEX...LI...OF -2.0 WITH A LI
OF -1.5 AT HILO. THE INSTABILITY WAS ALLOWING SOME SHOWERS TO BUILD
UP HIGH ENOUGH TO SPREAD LEEWARD ON THE SMALLER ISLANDS OVERNIGHT.
THE LEEWARD SHOWERS HAVE SUBSIDED...BUT BREEZY TRADE WINDS AND
SCATTERED WINDWARD SHOWERS WILL PERSIST THROUGH TOMORROW.

THE GLOBAL MODELS ARE IN GOOD AGREEMENT OVER THE NEXT SEVERAL DAYS.
THE MODELS SHOW A TROUGH ALOFT DIGGING OVER THE ISLANDS FROM THE
NORTHWEST OVER THE WEEKEND. THE TROUGH ALOFT WILL DESTABILIZE THE
ATMOSPHERE AND INDUCE A SURFACE TROUGH OVER THE ISLANDS WITH
SOUTHEAST FLOW NEAR THE BIG ISLAND AND NORTHEAST FLOW NEAR KAUAI.
THE SURFACE TROUGH WILL BRING MUCH WEAKER SURFACE WINDS...ESPECIALLY
OVER OAHU AND MAUI COUNTY. THE PREVAILING FLOW WILL BE LIGHT ENOUGH
FOR NIGHTTIME LAND BREEZES AND DAYTIME SEA BREEZES TO PREVAIL
STARTING SATURDAY AFTERNOON AND CONTINUING THROUGH MOST OF NEXT
WEEK. THE ATMOSPHERE WILL BE UNSTABLE ENOUGH FOR AFTERNOON SHOWERS
OVER INTERIOR AREAS WITH LOCALLY HEAVY SHOWERS POSSIBLE. WITH
SOUTHEAST FLOW NEAR THE BIG ISLAND AND LIGHT WINDS ELSEWHERE...VOG
WILL BE WIDESPREAD NEXT WEEK. THE COMPUTER MODELS SUGGEST TRADE
WINDS MAY START TO RETURN IN 8 OR 9 DAYS.

&&

.MARINE...
FRESH TRADES WILL CONTINUE THROUGH TOMORROW WITH SMALL CRAFT
ADVISORY CONDITIONS CONTINUING FOR THE KAIWI CHANNEL AS WELL AS THE
WINDIER WATERS NEAR MAUI AND THE BIG ISLAND. THESE WINDS MAY SUBSIDE
A BIT TONIGHT...AND SHOULD EASE BELOW ADVISORY LEVELS ON FRIDAY.

A SERIES OF LARGE SOUTH SWELLS WILL AFFECT THE ISLANDS IN THE NEXT
FEW OF DAYS. THE FIRST OF THESE SWELL LOOKS TO BE A TAD LATE...BUT
IS STILL EXPECTED THE SWELL TO ARRIVE LATER TODAY...BRINGING
ADVISORY LEVEL SURF TO ALL ISLANDS. A HIGH SURF ADVISORY IS UP
THROUGH EARLY SATURDAY MORNING.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT THE HAWAII TERMINALS TODAY EXCEPT FOR
MVFR CEILINGS AT PHNY.

AIRMET TANGO FOR LOW LVL TURB BELOW 080 SOUTHWEST OF THE MOUNTAINS
DUE TO THE BREEZY TRADE WINDS WILL CONTINUE THRU 170400 UTC.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR THE KAIWI
PAILOLO AND ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF
THE BIG ISLAND.

HIGH SURF ADVISORY FOR SOUTH FACING SHORES OF ALL ISLANDS UNTIL 6 AM
HST SATURDAY.

&&

$$
DONALDSON

000
FXHW60 PHFO 161400
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST THU MAY 16 2013

.SYNOPSIS...
A SURFACE HIGH PRESSURE NORTHEAST OF THE STATE WILL BRING MODERATE
TO FRESH TRADE WINDS TO THE ISLANDS THROUGH THE REST OF THE WORK
WEEK. PASSING LOW CLOUDS AND SHOWERS CARRIED BY THE WINDS WILL
AFFECT MAINLY WINDWARD AND MAUKA AREAS. AN UPPER LEVEL LOW
DEVELOPING NEAR THE ISLANDS THIS WEEKEND WILL RESULT IN LIGHTER
WINDS AND HELP TO ENHANCE SHOWER ACTIVITY LATE IN THE WEEKEND AND
INTO NEXT WEEK.

&&

.DISCUSSION...
TRADE WIND WEATHER PREVAILS OVER THE ISLANDS EARLY THIS MORNING...
WITH PASSING LOW CLOUDS AND SHOWERS AFFECTING MAINLY WINDWARD AND
MOUNTAIN AREAS. WINDS ARE STRONG ENOUGH TO CARRY SOME CLOUDS AND
SHOWERS TO THE LEE AREAS OF THE SMALLER ISLAND AT TIMES. THERE IS A
WEAK UPPER LEVEL LOW LINGERING IN THE ISLAND VICINITY...AND WILL
KEEP AIR MASS SOMEWHAT UNSTABLE. ON THE OTHER HAND...LIMITED LOW
LEVEL MOISTURE HAS KEPT PRECIPITATION AMOUNTS IN CHECK ACROSS THE
STATE AS LATEST RAINFALL REPORT FROM GAGES CONTINUES TO SHOW A LACK
OF PRECIPITATION. A BROAD AREA OF LOW CLOUDS HAS NOW REACHED
WINDWARD BIG ISLAND EARLY THIS MORNING...AND WILL SPREAD TO THE REST
OF THE ISLAND CHAIN AS THE DAY PROGRESSES. THE ARRIVAL OF THESE
CLOUDS MAY KEEP THE SKIES A LITTLE MORE CLOUDIER ACROSS THE ISLANDS
THIS MORNING...ESPECIALLY OVER THE WINDWARD AND MOUNTAIN AREAS.

THE SURFACE HIGH PRESSURE SYSTEM THAT IS RESPONSIBLE FOR THE TRADE
WINDS WILL REMAIN NEARLY STATIONARY TODAY THEN SLOWLY SHIFT EAST BY
THE WEEKEND AS A SURFACE TROUGH DEVELOPS IN THE ISLAND VICINITY.
IN THE MEAN TIME...TRADE WIND WEATHER WILL CONTINUE OVER THE
ISLANDS THROUGH THE REST OF THE WORK WEEK.

AN UPPER LEVEL TROUGH WILL DEEPEN NEAR THE ISLANDS BY THE
WEEKEND...AND WILL LEAD TO THE DEVELOPMENT OF A SURFACE TROUGH IN
THE ISLAND VICINITY. ONCE AGAIN...TRADE WINDS WILL DECREASE ACROSS
THE STATE...ALLOWING LOCAL LAND AND SEA BREEZES TO BECOME DOMINANT.
A CONVECTIVE WEATHER REGIME WILL ESTABLISH ACROSS THE STATE...WITH
CLOUDS AND SHOWERS DEVELOPING UNDER DAY-TIME HEATING...ESPECIALLY
OVER THE INTERIOR SECTIONS OF THE ISLANDS. EVEN THOUGH FORECAST
CHARTS HINT MOST OF THE UNSTABLE AIR MASS MAY REMAIN NORTH OF THE
STATE...DEPENDING ON THE AVAILABLE LOW LEVEL MOISTURE...LOCALLY
HEAVY RAINS MAY STILL BE POSSIBLE. DO NOT ANTICIPATE WIDESPREAD
VOLCANIC EMISSIONS FROM THE BIG ISLAND TO AFFECT THE SMALLER ISLANDS
AT THIS TIME...AS THE SURFACE TROUGH IS EXPECTED TO POSITION PRETTY
MUCH ACROSS THE CENTRAL PORTION OF THE ISLAND CHAIN.
NEVERTHELESS...LOCALLY HAZY CONDITIONS MAY STILL DEVELOP ON THE
SMALLER ISLANDS UNDER THE LIGHT WINDS. THIS SURFACE TROUGH IS
EXPECTED TO LINGER OVER THE ISLANDS THROUGH EARLY PART OF NEXT WEEK.
LATEST FORECAST CHARTS DO INDICATE A POSSIBLE RETURN OF TRADE WINDS
TO THE STATE TOWARDS THE LATER PART OF NEXT WEEK.

&&

.MARINE...
FRESH TRADES WILL CONTINUE THROUGH FRIDAY...BRINGING SMALL CRAFT
ADVISORY CONDITION FOR THE KAIWI CHANNEL AS WELL AS THE WINDIER
COASTAL WATERS NEAR MAUI AND THE BIG ISLAND. THESE WINDS MAY SUBSIDE
A BIT TONIGHT...AND SHOULD EASE BELOW ADVISORY LEVELS ON FRIDAY.

A SERIES OF LARGE SOUTH SWELLS WILL AFFECT THE ISLANDS IN THE NEXT
FEW OF DAYS. THE FIRST OF THESE SWELL LOOKS TO BE A TAD LATE...AS
LATEST DATA FROM THE BUOYS SOUTH OF THE ISLANDS ONLY HAVE HINTS OF
THE LONG PERIOD SWELL. STILL EXPECTED THE SWELL TO ARRIVE LATER
TODAY...BRINGING ADVISORY LEVEL SURF TO ALL ISLANDS. A HIGH SURF
ADVISORY IN EFFECT FROM 6 AM THURSDAY MORNING FOR ALL SOUTH FACING
SHORES. AS THE SERIES OF LARGE SOUTH SWELLS CONTINUES THROUGH THE
NEXT FEW DAYS...THE HIGH SURF ADVISORY MOST LIKELY BE EXTENDED
THROUGH THE WEEKEND.

FRESH TRADE WINDS WILL ALSO BRING ELEVATED SHORT PERIOD WAVES TO
EAST FACING SHORES FOR THE NEXT COUPLE OF DAYS...THOUGH SURF
HEIGHTS WILL REMAIN BELOW ADVISORY LEVEL. THESE WAVES WILL SUBSIDE
BY THE WEEKEND AS THE WINDS DECREASE.

&&

.AVIATION...
A LARGE PATCH OF LOW CLOUDS WITH A FEW EMBEDDED SHOWERS WILL BE
MOVING THROUGH THE ISLANDS TODAY. IT APPEARS THESE CLDS ARE OF THE
STABLE VARIETY WITH BASES ABV 030...BTN 050-070. THEY WIL LIKELY
DISSIPATE AS THE DAY PROGRESSES AS WELL. SO NO AIRMET FOR MTN OBSC
IS NECESSARY AT THIS POINT...BUT WILL BE MONITORED CLOSELY. SURELY
THERE WILL BE BRIEF DURATIONS OF MVFR CIG...FAVORING THE WINDWARD
AND MTN AREAS OF ALL ISLANDS.

AIRMET TANGO FOR LO LVL TURB BELOW 080 IMMEDIATELY S THRU W OF MTN
WILL CONT THRU 170400 UTC.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR KAIWI CHANNEL-
MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD
WATERS-BIG ISLAND SOUTHEAST WATERS.

HIGH SURF ADVISORY FOR SOUTH FACING SHORES OF ALL ISLANDS 6 AM HST
TODAY UNTIL 6 AM HST SATURDAY.

&&

$$

DISCUSSION/MARINE...HUI
AVIATION...LAU