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Hawaiian Islands Synoptic Discussion and Guidance

691
FXHW60 PHFO 081412
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SAT MAR 8 2014

.SYNOPSIS...
A COLD FRONT NEAR THE BIG ISLAND WILL CONTINUE TO BRING CLOUDS AND
PRECIPITATION TO THE STATE TOADY. RAINFALL CHANCES WILL REMAIN
HIGHEST ALONG WINDWARD TERRAIN. TRADE WINDS WILL SPREAD ACROSS THE
THE STATE BEHIND THE FRONT AND WILL PERSIST THROUGH MOST OF
NEXT WEEK. ANOTHER FRONTAL SYSTEM MAY REACH THE AREA NEXT WEEKEND.
LARGE AND HAZARDOUS SURF IS EXPECTED ALONG NORTH FACING BEACHES
THROUGH THE WEEKEND.

&&

.DISCUSSION...
EVEN THOUGH MUCH OF THE CLOUD BAND ASSOCIATED WITH THE COLD FRONT IS
COVERING MAINLY THE SMALLER ISLANDS EARLY THIS MORNING...VERTICAL
WIND PROFILE DATA FROM RADAR ON THE BIG ISLAND SUGGESTED THE FRONT
HAS ALREADY REACHED THAT ISLAND. THE FRONT DID BRING MEASURABLE
PRECIPITATION TO THE SMALLER ISLANDS...THOUGH NOT ENOUGH POSE ANY
PROBLEM. LOOKS LIKE BIG ISLAND WILL SEE THE LEAST OF THE RAINFALL
AMOUNTS FROM THIS SYSTEM. THERE ARE STILL MOISTURE PERSISTING ACROSS
THE ISLAND CHAIN...AND WILL PROVIDE SOME SHOWERS...ESPECIALLY FOR
THE WINDWARD AND MOUNTAIN AREAS TODAY. THE MID AND HIGH LEVEL CLOUDS
ASSOCIATED WITH THE SYSTEM ARE EXPECTED TO SLOWLY CLEAR THE STATE
FROM THE EAST LATER TODAY...AS THE ASSOCIATED UPPER LEVEL TROUGH
MOVES EAST OF THE ISLANDS. NORTHERLY WINDS BEHIND THE FRONT WILL
SPREAD ACROSS THE ISLANDS AS WELL...AND WILL TURN MORE EASTERLY
AS A SURFACE HIGH PRESSURE CURRENTLY NORTHWEST OF THE STATE MOVES
EAST LATER TODAY.

TRADE WIND WEATHER IS EXPECTED TO RETURN TO THE ISLANDS NEXT
WEEK...WITH CLOUDS AND SHOWERS AFFECTING MAINLY WINDWARD AND
MOUNTAIN AREAS...WHILE AFTERNOON CONVECTION MAY AFFECT THE LEE
AREAS OF THE BIG ISLAND AS WELL. FORECAST CHARTS STILL INDICATE AN
UPPER LEVEL TROUGH WILL DEEPEN EAST OF THE STATE BEGINNING
TUESDAY...THOUGH ITS MAIN AXIS WILL LOCATE A LITTLE FURTHER EAST
THAN EARLIER MODEL RUNS. THEREFORE ITS EFFECT ON THE ISLANDS WEATHER
WILL BE LIMITED...WITH POSSIBLE ENHANCED RAINFALL FOR THE STATE
MONDAY AND TUESDAY. THE STRONG UPPER LEVEL JET EXPECTED ALONG
THE WESTERN FLANK OF THE DEEPENING SYSTEM MAY BRING WINDY
CONDITIONS TO THE BIG ISLAND SUMMITS AS WELL.

TRADE WINDS ARE EXPECTED TO WEAKEN A TAD MONDAY...AS THE SURFACE
HIGH PRESSURE MOVES FAR NORTHEAST OF THE STATE. ANOTHER SURFACE HIGH
PRESSURE FROM THE NORTHWEST WILL PASS THE ISLANDS LATER NEXT
WEEK...AND WILL PROVIDE STRONGER TRADE WINDS TO THE ISLANDS
BEGINNING TUESDAY.

MODEL RUNS STILL SUGGEST ANOTHER FRONTAL SYSTEM WILL APPROACH THE
STATE NEXT WEEKEND...BRINGING POSSIBLE WET WEATHER TO THE ISLANDS
AGAIN. THE DIFFERENCE WITH THIS PENDING SYSTEM FROM THE OTHERS IS
THAT IT LOOKS MORE LIKE A SHEAR LINE WHEN IT REACHES THE
STATE...WITH THE PRESENT OF A STRONG SURFACE HIGH PRESSURE
SYSTEM BEHIND THE FRONT. BOTH THE EUROPEAN MODEL AS WELL AS GFS ARE
IN QUITE GOOD AGREEMENT ON THIS WEATHER SCENARIO. THEREFORE TRADE
WINDS ARE EXPECTED TO HOLD EVEN AS THIS SYSTEM APPROACHES THE
ISLANDS...AND BECOME RATHER STRONG OVER THE STATE BY THE LATER PART
OF NEXT WEEKEND.

&&

.MARINE...
THE INCOMING NORTHERLY SWELL HAS REACHED OAHU EARLY THIS MORNING
AND WILL CONTINUE TO SPREAD TO THE REST OF THE ISLANDS THROUGH THE
TODAY. IN FACT...THIS SWELL IS EXPECTED TO PEAK TODAY THEN SLOWLY
SUBSIDE TONIGHT . A HIGH SURF WARNING REMAINS IN EFFECT THROUGH
EARLY SUNDAY MORNING FOR NORTH AND WEST FACING SHORES FOR MOST OF
THE SMALLER ISLANDS.

A SMALL CRAFT ADVISORY REMAINS POSTED FOR ALL WATERS EXPOSED TO THE
INCOMING NORTHWEST SWELL THROUGH NOON SUNDAY. TRADE WINDS MAY
BECOME STRONG ENOUGH BY THE LATER PART OF NEXT WEEK TO BRING SMALL
CRAFT CONDITIONS TO THE COASTAL WATERS...AT LEAST IN THE CHANNELS.
THE ISLANDS WILL PROBABLY SEE STRONG ENOUGH TRADE WINDS TO WARRANT
SMALL CRAFT ADVISORY FOR ALL WATERS BY NEXT WEEKEND...WITH POSSIBLE
GALE CONDITIONS FOR THE USUAL WINDY CHANNELS.

&&

.AVIATION...
WEAKENING FRONTAL BOUNDARY HAS STALLED OVER THE STATE THIS MORNING.
AN UPPER TROUGH PASSING OVERHEAD CONTINUES TO PRODUCE BROKEN TO
OVERCAST LAYERED CLOUDS IN THE VICINITY OF THE FRONT FROM KAUAI TO
THE ALENUIHAHA CHANNEL. THE TROUGH IS MOVING EAST AND KAUAI SHOULD
BE SEEING A DECREASE IN CLOUDS LATER THIS MORNING. EXPECT THE
CENTRAL ISLANDS TO CONTINUE SEEING SOME MVFR AND ISOL IFR CEILINGS
AND VISIBILITIES THROUGH TODAY WITH IMPROVING CONDITIONS TONIGHT.

AIRMET SIERRA FOR MOUNTAIN OBSCURATION CURRENTLY REMAINS IN EFFECT
FROM KAUAI TO MAUI WITH KAUAI EXPECTED TO BE THE FIRST TO IMPROVE
LATER THIS MORNING. SOUNDINGS STILL INDICATE ENOUGH MOISTURE IN THE
MID LEVELS TO LEAD TO SOME LIGHT TO MODERATE ICING...MAINLY BETWEEN
15K AND 18K FT. THUS AIRMET FOR ICING EXISTS FOR MAUI COUNTY AND
OAHU.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 6 AM HST SUNDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-OAHU
KOOLAU-OLOMANA-MOLOKAI-MAUI WINDWARD WEST-WINDWARD HALEAKALA.

SMALL CRAFT ADVISORY UNTIL NOON HST SUNDAY FOR ALL ZONES EXCEPT
MAALAEA BAY.

&&

$$

AVIATION...FUJII
REST...HUI

Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office

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