AFDHFO

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
410 PM HST FRI JUL 8 2011

.SYNOPSIS...
STRONG TRADE WINDS DRIVEN BY A SUBTROPICAL HIGH FAR NORTH OF THE
STATE WILL CONTINUE TONIGHT WITH A GRADUAL WEAKENING EXPECTED OVER
THE WEEKEND. TRADE WINDS WILL THEN REMAIN MODERATE NEXT WEEK.
CLOUDS AND SHOWERS FOCUS ON WINDWARD AND MAUKA AREAS THROUGH THE
FORECAST PERIOD WITH MOST RAIN OCCURRING DURING THE NIGHT AND EARLY
MORNINGS. AN UPPER LOW WILL APPROACH FROM THE EAST ON SATURDAY NIGHT
AND THEN PASS JUST NORTH OF THE ISLAND CHAIN DURING THE FIRST HALF
OF NEXT WEEK. SHOWERS MAY BECOME ENHANCED BY THE UPPER LOW SATURDAY
NIGHT THROUGH TUESDAY.

&&

.DISCUSSION...
A NEARLY STATIONARY 1030 MB SURFACE HIGH IS CENTERED 38N 158W...1125
MILES NORTH OF HAWAII. THIS HIGH IS DRIVING STRONG TRADE WINDS
ACROSS THE HAWAIIAN ISLANDS AND DRY AND STABLE CONDITIONS PERSIST
AROUND THE STATE. AFTERNOON SOUNDINGS AT HILO AND LIHUE SHOWED A
INVERSION HEIGHTS AT AROUND 8000 FEET...AND PRECIPITABLE WATER /PW/
VALUES AT 1.1 INCHES. AMSU/SSMI SATELLITE PW VALUES SHOW EVEN DRIER
AIR UPSTREAM TO THE EAST. SO EXPECTING A BREEZY BUT FAIRLY DRY NIGHT
WITH THE EXCEPTION OF A FEW PASSING WINDWARD AND MAUKA SHOWERS.

MIDLEVEL WINDS CONTINUE TO BE GUSTY AS THE MIDLEVEL HIGH REMAINS
STRONG AND PARKED ON TOP OF THE SURFACE HIGH. REPORTS OF 30 TO 40
MPH WINDS THE MAUNA KEA SUMMIT OBSERVATORIES CONTINUE LATE THIS
AFTERNOON AND THE HIGH WIND ADVISORY REMAINS IN EFFECT UNTIL EARLY
SATURDAY MORNING FOR THE BIG ISLAND SUMMITS. MODELS INDICATE WINDS
AT THOSE ELEVATIONS TO DECREASE TONIGHT.

SURFACE LEVEL WINDS ACROSS THE STATE WILL REMAIN STRONG THROUGH
SATURDAY...WITH A WEAKENING EXPECTED TO OCCUR SATURDAY NIGHT THROUGH
MONDAY. WINDS WILL THEN REMAIN MODERATE THROUGH THE NEXT WORK WEEK.
THE REASON FOR THE DECREASED TRADES IS BECAUSE AN UPPER LOW
CURRENTLY NEAR 21N 142W WILL APPROACH FROM THE EAST ON SATURDAY
NIGHT AND THEN PASS JUST NORTH OF THE ISLAND CHAIN DURING THE FIRST
HALF OF NEXT WEEK. THE UPPER LEVEL LOW WILL HELP TO DISRUPT THE
TRADE WIND FLOW AS IT SLOWLY DRAGS A MIDLEVEL AND SURFACE LOW SOUTH
OF THE HAWAIIAN ISLANDS...DECREASING THE PRESSURE GRADIENT ACROSS
THE AREA. WINDS ARE EXPECTED TO REMAIN MODERATE FROM SUNDAY THROUGH
MOST OF NEXT WEEK AS A RESULT. MOST OF THE ENERGY AND LOW LEVEL
TROPICAL MOISTURE WILL REMAIN FAR SOUTH OF OUR AREA THOUGH.
HOWEVER...THE TRADE TYPICAL SHOWERS MAY BECOME ENHANCED BY THE UPPER
LOW BEGINNING SATURDAY NIGHT THROUGH TUESDAY. THE GFS AND ECMWF HAVE
COME INTO BETTER ALIGNMENT AS FAR THE UPPER LOW TRACK...WHICH AT
THIS TIME IS EXPECTED TO SLOWLY TRACK FROM EAST OF THE BIG ISLAND
SATURDAY NIGHT TO A POSITION JUST NORTH OF KAUAI BY WEDNESDAY. BY
WEDNESDAY...MUCH OF THE UPPER LEVEL DYNAMIC ENERGY WILL BE NORTH OF
THE STATE AND WE WILL GO INTO A NORMAL MODERATE TRADE WIND AND
RAINFALL DISTRIBUTION REGIME.

CLOUDS AND SHOWERS FOCUS ON MOSTLY OVER WINDWARD/MAUKA AREAS THROUGH
THE FORECAST PERIOD WITH MOST RAIN OCCURRING DURING THE NIGHT AND
EARLY MORNINGS. THIS WILL BE PARTICULARLY TRUE AS THE TRADES WEAKEN
SUNDAY INTO NEXT WEEK AND RAIN SHADOWING EFFECT INCREASES.

&&

.AVIATION...
DUE TO STRONG TRADES...AIRMET TANGO WILL CONTINUE FOR LOW LEVEL
TURBULENCE FOR AREAS BELOW 070 S THRU W OF MOUNTAINS FOR KAUAI OAHU
AND MOLOKAI AND BELOW 150 S THRU W OF MOUNTAINS FOR LANAI MAUI AND
THE BIG ISLAND. ISOLATED SEVERE TURBULENCE EXPECTED BELOW 080 S THRU
W OF MOUNTAINS FOR LANAI MAUI AND THE BIG ISLAND.

&&

.MARINE...
SOLID SSW SWELL CONTINUES ACROSS EXPOSED S FACERS TODAY. MOST AREAS
ARE RUNNING SEVERAL FEET OVERHEAD ON THE SETS...HOWEVER THE LARGEST
SETS ARE STAYING FOCUSED ON THE SMALLER CHANNEL ENTRANCES AND
STANDOUT REEFS THAT HANDLE THE SIZE/DIRECTION BEST. WILL BE LEAVING
6-10 FT IN THE FORECAST PRODUCT FOR THE REMAINDER OF THE DAY. SURF
IN THE 8-10 FT IS STILL POSSIBLE WITH FAIR CONSISTENCY IN THE RIGHT
PLACES. LARGER SETS REACHING 10 FT CAN BE MORE HAZARDOUS AS
CONSISTENCY DROPS BECAUSE SWIMMERS/SURFERS TEND TO GET CAUGHT OFF
GUARD IN THIS SITUATION. THE SWELL WILL LOWER TOMORROW WITH SURF TO
8 FT STILL POSSIBLE THROUGH THE AFTERNOON. SURF ALONG WINDWARD REEFS
REMAINS ELEVATED AS WELL DUE TO THE HOWLING TRADE WINDS. E FACING
SHORES WILL REMAIN IN THE HIGH SURF ADVISORY AS WELL. AS OF
NOW...THE ADVISORY FOR BOTH THE S AND E SWELLS SHOULD BE HISTORY BY
TOMORROW AFTERNOON SOMETIME WITH SMALLER SURF EXPECTED SUN. BEYOND
THAT...ANOTHER SMALL S SWELL SHOWS MON...WITH AT LEAST AVERAGE JULY
SURF EXPECTED FOR THE SECOND HALF OF THE WEEK...PERHAPS LARGER.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 PM SATURDAY FOR SOUTH FACING SHORES OF
ALL ISLANDS.

HIGH SURF ADVISORY UNTIL 6 PM SATURDAY FOR EAST FACING SHORES OF
KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG ISLAND.

WIND ADVISORY UNTIL 6 AM HST SATURDAY FOR BIG ISLAND SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST SATURDAY FOR ALL HAWAIIAN
WATERS.

&&

$$