Drought in Hawaii, February 1 to 28, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST SAT JAN 31 2009

.SYNOPSIS...
HIGH PRESSURE NORTH OF THE MAIN HAWAIIAN ISLANDS WILL KEEP LIGHT TO
MODERATE TRADE WINDS BLOWING THROUGH SUNDAY. A SHEARLINE WILL MOVE
ACROSS THE ISLANDS FROM THE NORTHWEST MONDAY AND TUESDAY...USHERING
IN STRONGER TRADE WINDS AND MORE SHOWERS MAINLY ACROSS WINDWARD AND
MAUKA AREAS. THE STRONGER WINDS WILL PUSH SHOWERS ACROSS LEEWARD
AREAS AS WELL FROM TIME TO TIME. LIGHTER TRADE WINDS AND DRIER
CONDITIONS ARE EXPECTED FROM WEDNESDAY ONWARDS AS THE SHEARLINE
DISSIPATES.

&&

.DISCUSSION...
A RIDGE OF HIGH PRESSURE NORTH OF THE MAIN HAWAIIAN ISLANDS EXTENDS
THROUGH 34N140W...29N150W AND 32N180W WHERE A 1029 MB SURFACE HIGH
HAS JUST CROSSED EASTWARD INTO THE CENTRAL NORTH PACIFIC. THIS RIDGE
IS 600 TO 700 MILES NORTH OF THE ISLANDS AND IS SUFFICIENTLY STRONG
TO INDUCE 15 MPH EASTERLY TRADE WINDS ACROSS LOCAL WATERS THIS
EVENING. AFTERNOON SOUNDINGS SHOW OUR AIRMASS IS SLOWLY BECOMING
MORE MOIST...WITH ABOUT AN INCH OF PRECIPITABLE WATER NOTED.
HOWEVER...CLOUD COVER ACROSS HAWAIIAN WATERS WAS RATHER SPARSE WITH
RADAR SHOWING ONLY VERY LIGHT AND ISOLATED SHOWERS 30 TO 60 MILES
NORTHEAST OF OAHU AND MOLOKAI. A FEW SHOWERS WERE ALSO NOTED WITHIN
THE PLUME 100 MILES OR SO WEST OF THE BIG ISLAND. WE EXPECT LIGHT TO
MODERATE EASTERLY TRADES WILL CONTINUE THROUGH THE DAY SUNDAY WITH
CONTINUED RATHER DRY CONDITIONS.

THE FORECAST CALLS FOR THE ARRIVAL OF A SHEARLINE EARLY MONDAY. THIS
FEATURE IS NOW A COLD FRONT SEVERAL HUNDRED MILES NORTHWEST OF KAUAI
THIS EVENING...BUT MODELS SHOW THE FRONT WEAKENING TO A SHEARLINE BY
THE TIME IT REACHES KAUAI. THE ASSOCIATED STREAMLINE COL WILL BE FAR
NORTH OF THE ISLANDS...RESULTING IN SHARPLY STRONGER TRADE WINDS AS
THE FEATURE SETTLES IN INSTEAD OF THE PREVIOUS PATTERN OF
PRE-FRONTAL SOUTHERLIES FOLLOWED BY POST-FRONTAL NORTHWESTERLIES.
GFS SHOWS THE STRONGER TRADES WILL BRING IN MORE MOISTURE...ALTHOUGH
ONLY WITHIN A RELATIVELY SHALLOW LAYER. THE RESULT WILL BE A
TRANSITION FROM A DRY AND MELLOW TRADE WIND PATTERN TO A WET AND
WINDY ONE. CLOUDS AND SHOWERS WILL FAVOR WINDWARD AND MAUKA
AREAS...BUT THE STRONGER TRADES WILL BLOW SHOWERS ACROSS LEEWARD
AREAS AS WELL FROM TIME TO TIME. BY WEDNESDAY...THE SHEARLINE WILL
BE DISSIPATING...RESULTING IN LIGHTER TRADE WINDS AND DRIER
CONDITIONS. HOWEVER...RESIDUAL MOISTURE WILL STILL LIKELY BE HUNG UP
ALONG BIG ISLAND SLOPES THROUGH WEDNESDAY.

THURSDAY AND FRIDAY SHOULD SEE A RETURN TO TRADE WIND WEATHER
CONDITIONS SIMILAR TO WHAT WE WERE SEEING TODAY. MODELS SHOW WINDS
VEERING TO SOUTHEASTERLIES AGAIN NEXT WEEKEND AS ANOTHER TROUGH
APPROACHES FROM THE NORTHWEST.

&&

.MARINE...
THE NEXT SIGNIFICANT NORTHWEST SWELL WITH THE POTENTIAL FOR A HIGH
SURF ADVISORY IS LATE MONDAY. FRESH AND GUSTY TRADE WINDS WILL
ACCOMPANY THE FORECAST SHEAR LINE MONDAY AND TUESDAY. THE STRENGTH
OF THE INCREASED TRADES MAY REQUIRE THE ISSUANCE OF SMALL CRAFT
ADVISORIES FOR MOST LOCAL WATERS AND CHANNELS. ROUGH...LOCALLY
GENERATED WIND WAVES COMBINED WITH THE NORTHWEST SWELL WILL LIKELY
PRODUCE COMBINED SEAS OF 10 FT OR MORE AS WELL.

WE ANTICIPATE THAT AREAS UNDER SMALL CRAFT ADVISORIES WILL BE SCALED
DOWN TO TYPICALLY WINDY AREAS WEDNESDAY NIGHT OR THURSDAY...LIMITED
TO AREAS SUCH AS WATERS NORTH AND SOUTH OF THE BIG ISLAND AND
MAALAEA BAY JUST LEE OF MAUI.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

POWELL