Wednesday, April 16, 2014 596-SURF , 596-WAVE , 922-BONG , 638-RUSH , 572-SURF(MAUI) , 241-SURF (KAUAI) , 324-RUSH (BIG ISLAND)
   
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000
FXHW60 PHFO 160202
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
402 PM HST TUE APR 15 2014

.SYNOPSIS...
TRADE WINDS WILL GRADUALLY EASE TO MODERATE TO FRESH BREEZES BY
WEDNESDAY...DELIVERING SHOWERS TO WINDWARD AND MAUKA AREAS AND
OCCASIONALLY TO LEEWARD SIDES. WIND SPEEDS ARE EXPECTED TO
INCREASE SLIGHTLY SUNDAY AND MONDAY.

&&

.DISCUSSION...
BREEZY TRADE WINDS ACROSS THE ISLANDS ARE BEING DRIVEN BY A 1029
MB SURFACE HIGH CENTERED ABOUT 1500 MILES TO THE NORTHEAST. WINDS
WILL TAPERING OFF OVER THE NEXT DAY OR TWO AS THE HIGH WEAKENS AND
SLIDES SOUTHWARD. EVIDENCE OF THE WEAKENING HIGH PRESSURE IS
OBSERVED IN THE STATION SURFACE PRESSURES DOWN 2 MB PLUS SINCE
YESTERDAY. SUSTAINED WINDS AND GUSTS HAVE FALLEN BELOW ADVISORY
THRESHOLD ACROSS THE WHOLE STATE...AND HAVE JUST CANCELLED THE
WIND ADVISORY THAT HAS BEEN IN PLACE FOR PORTIONS OF MAUI COUNTY
AND BIG ISLAND TODAY. THE TRADE WINDS WILL REMAIN MODERATE TO
FRESH THROUGH THE REST OF THE WORK WEEK.

SOUNDINGS FROM THIS AFTERNOON AT HILO SHOWS THE MIDLEVEL INVERSION
UP TO NEAR 9000 FEET...WHILE IT IS 6000 FEET AT LIHUE. PRECIPITABLE
WATER VALUES ARE 1.23 INCHES AT HILO AND 0.92 INCHES AT LIHUE. THE
ELEVATED INVERSION HEIGHT ON THE BIG ISLAND IS RESULTING FROM A
DEVELOPING TUTT...OR TROPICAL UPPER TROPOSPHERIC TROUGH...ACROSS
THE EASTERN PART OF THE STATE. WINDWARD AND MAUKA SHOWERS ARE
BLOWING IN WITH THE TRADE WINDS...AND HAVE BEEN A LITTLE BIT
HEAVIER OVER WINDWARD MAUI AND BIG ISLAND THIS AFTERNOON DUE TO
THIS UPPER LEVEL FEATURE. THE TUTT WILL REMAIN OVER THE STATE
THROUGH MONDAY OF NEXT WEEK... BUT THE INFLUENCE OF THE TUTT WILL
BE MINOR THROUGH THE REST OF THE WEEK DUE TO SOLID MIDLEVEL RIDING
OVER THE STATE.

THROUGH FRIDAY...TRADES WILL CONTINUE TO BRING IN MOISTURE FROM UPSTREAM
PRODUCING PRIMARILY WINDWARD CLOUDS AND SHOWERS. SOME PASSING
SHOWERS SHOULD MAKE IT ONTO LEEWARD SIDES OF THE SMALLER ISLANDS
DUE TO THE BREEZY WINDS. RAINFALL AMOUNTS SHOULD BE LIGHT TO
MODERATE AND OCCUR MOSTLY DURING THE NIGHTTIME HOURS.

THE TUTT WILL BEGIN TO RAISE AND WEAKEN THE MIDLEVEL TRADE WIND
INVERSION SATURDAY AND SATURDAY NIGHT. THIS MAY PROVIDE A BIT OF
ENHANCEMENT TO THE TRADE SHOWERS...THOUGH MOISTURE LEVELS MAY BE
LACKING SOMEWHAT AT THAT TIME. AT THE SURFACE...A NEW HIGH WILL
BUILD NORTHWEST OF THE ISLANDS...AND PASS FAR NORTH OF THE ISLANDS
THIS WEEKEND. THIS WILL BRING SLIGHTLY STRONGER TRADE WINDS TO THE
ISLANDS ON SUNDAY AND MONDAY.

&&

.AVIATION...
23Z-00Z AMDAR SOUNDINGS FROM LIH/HNL/OGG/KOA AND RADAR VAD WIND
PROFILES SHOW 25+ KNOTS OF WIND BELOW THE LOW-LEVEL INVERSION. 00Z
RAOBS SHOW INVERSIONS HEIGHTS REMAIN HIGHER IN HILO THAN IN
LIHUE...BUT WITH SOME MID-LEVEL WARMING STRENGTHENING THE INVERSION.
WITH LITTLE CHANGE IN THE PATTERN EXPECTED FOR TONIGHT...WE WILL
MAINTAIN THE AIRMET FOR MODERATE TURBULENCE IN THE LEE OF THE
ISLANDS. THE AIRMET MAY CONTINUE AT LEAST THROUGH WEDNESDAY AS GFS
FORECAST SOUNDINGS SHOW STABLE CONDITIONS AND LOW-LEVEL WINDS OVER
25 KNOTS...WITH WINDS DIMINISHING FURTHER WEDNESDAY NIGHT.

STRONG TRADE WINDS WILL FOCUS MOST RAINFALL ACROSS WINDWARD AREAS...
BUT BRIEF SHOWERS WILL ALSO AFFECT LEEWARD SECTIONS AS WELL.
CONDITIONS WILL BE PRIMARILY VFR...WITH OCCASIONAL MVFR CEILINGS AND
BRIEF MVFR VISIBILITIES IN SHOWERS MAINLY ACROSS WINDWARD AREAS.


&&

.MARINE...
ASCAT PASS FROM THIS AFTERNOON SHOWS 25 TO 30 KNOT WINDS ACROSS
THE CHANNELS. AS A RESULT...THE SMALL CRAFT ADVISORY /SCA/ IS EXTENDED
UNTIL WEDNESDAY MORNING FOR THE CHANNELS AND WATERS NORTHWEST OF
KAUAI...AND THROUGH FRIDAY FOR THE WINDIER ZONES AROUND MAUI AND
THE BIG ISLAND. TRADE WINDS WILL BE GRADUALLY TAPERING OFF
TONIGHT...AND REMAIN MODERATE TO FRESH THROUGH THE REST OF THE
WORK WEEK. THE HIGH SURF ADVISORY HAS ALSO BEEN EXTENDED FOR EAST
FACING SHORES UNTIL WEDNESDAY MORNING DUE TO THE LOCAL WIND WAVES.

A SMALL WEST-NORTHWEST SWELL WILL ARRIVE LATE WEDNESDAY AND PEAK THURSDAY
WITH PEAK SURF HEIGHTS REMAINING BELOW ADVISORY LEVELS. NO OTHER
SIGNIFICANT SWELLS ARE EXPECTED.


&&

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

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

SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR KAUAI
NORTHWEST WATERS-KAUAI CHANNEL-KAIWI CHANNEL.


&&

$$

DISCUSSION/MARINE...FOSTER
AVIATION...BRAVENDER


THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD

HAWAII EXTENDED FORECAST DISCUSSION




HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
747 AM EDT TUE APR 15 2014

VALID 00Z WED APR 16 2014 - 00Z WED APR 23 2014

OF THE 15/00Z ECENS/GEFS/CMC MEANS AND THEIR DETERMINISTIC
RUNS...THE ECENS AND THE ECMWF PROVIDED THE BEST
CONSISTENCY...WITH THE CANADIAN AND ITS MEAN A CLEAR SECOND CHOICE
THROUGH DAY 7 FOR MUCH OF THE NORTHERN PACIFIC OCEAN AND
SUBTROPICS.

THE 15/00Z GEFS/GFS SOLUTION ALOFT (500MB LEVEL) WAS CERTAINLY
VIABLE UNTIL 20/12Z ALONG THE DATELINE AND EAST OF 140W LONGITUDE.
HOWEVER...AFTER 20/12Z...THIS PIECE OF GUIDANCE BECOMES A VERY
FAST OUTLIER--BREAKING OFF A CUTOFF LOW IN THE SOUTHERN GULF OF
ALASKA AND TAKING IT INTO THE MAINLAND WEST COAST A GOOD DAY
EARLIER THAN THE CANADIAN/ECMWF DETERMINISTIC/ENSEMBLE MEAN
SOLUTIONS. THE GFS/GEFS IS AN EVEN FASTER SOLUTION INVOF ALEUTIANS
BETWEEN DAY 6-7...AND THE 15/06Z GFS/GEFS WAS EVEN FASTER!

RECOMMEND USING A BLEND OF THE 15/00Z ECENS MEAN AND ITS
DETERMINISTIC SOLUTION. ANTICIPATE SOME DECREASE IN THE TRADE
WINDS DURING THE FRI/SAT TIME FRAME AS A DEEPENING MID-LATITUDE
CYCLONE TAKES SHAPE IN THE GULF OF ALASKA AND DAMPENS THE
SUBTROPICAL RIDGE FOR 24-26 HOURS. AFTER 20/00Z...THE SURFACE HIGH
OVER THE 'SUBTROPICAL-LATITUDE' PACIFIC APPEARS TO RE-ESTABLISH
ITSELF NORTH OF THE ISLANDS FOR DAYS 5-7. BUT THE CENTRAL PRESSURE
OF THE 'NEW' SURFACE HIGH LOOKS TO BE A GOOD 3-5 MILLIBARS WEAKER
THAN THE CURRENT 1034 MB+ CELL INVOF 38.5N 144W.       

VOJTESAK





Last Updated: 747 AM EDT TUE APR 15 2014




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