Drought in Hawaii, June 1 to 30, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST THU MAY 31 2012

.SYNOPSIS...
MODERATE TO LOCALLY STRONG TRADE WINDS WILL PERSIST WELL INTO NEXT
WEEK. SHOWERS WILL FAVOR WINDWARD AND MAUKA SECTIONS...WITH SOME
PASSING OVER LEEWARD AREAS.

&&

.DISCUSSION...
A RIDGE OF HIGH PRESSURE FAR NORTH OF THE MAIN HAWAIIAN ISLANDS IS
ANCHORED BY A PAIR OF 1026 MB SURFACE HIGHS NEAR 30N140W AND
30N156W. THE PRESSURE GRADIENT BETWEEN THIS RIDGE AND EQUATORIAL LOW
PRESSURE IS SUFFICIENTLY STEEP TO SUPPORT MODERATE TO LOCALLY STRONG
EST NORTHEAST TRADE WINDS ACROSS THE MAIN HAWAIIAN ISLANDS AND LOCAL
WATERS THIS EVENING. THIS RIDGE WILL BE A PERSISTENT FEATURE THROUGH
THE FORECAST PERIOD.

TERRAIN INTERACTION ON EITHER SIDE OF THE RELATIVELY NARROW PAILOLO
CHANNEL CAUSES WINDS TO LOCALLY INCREASE ACROSS LANAI WHEN THEY ARE
BLOWING FROM THE 30 TO 50 DEGREE DIRECTION. SINCE WINDS HAVE VEERED
OUTSIDE THIS RANGE...WIND SPEEDS HAVE DECREASED ENOUGH ACROSS LANAI
TO DROP THE WIND ADVISORY. HOWEVER...THANKS TO STRONG FLOW
LOFT...WINDS ARE INCREASING ACROSS THE BIG ISLAND
SUMMITS...PROMPTING THE ISSUANCE OF A WIND ADVISORY THERE UNTIL 6 PM
HST FRIDAY.

THE SURFACE RIDGE STRETCHING EAST TO WEST ALONG 30N WILL PUT THE
ISLANDS IN MODERATE TO LOCALLY STRONG TRADE WINDS THROUGH THE FIRST
HALF OF NEXT WEEK. WINDS WILL BE STRONGEST THROUGH VALLEYS SUCH AS
THE CENTRAL VALLEY OF MAUI...AND WILL OCCUR MAINLY IN THE AFTERNOON.
SHOWERS WILL WET WINDWARD SECTIONS...WITH SOME PASSING OVER THE
MOUNTAINS OF KAUAI OAHU AND MOLOKAI TO LEEWARD AREAS IN THE BRISK
TRADES.

EARLIER GFS MODEL RUNS SHOWED AN UPPER LOW DRIFTING WESTWARD ACROSS
THE ISLANDS EARLY NEXT WEEK...POSSIBLY ENHANCING TRADE SHOWERS.
HOWEVER...THE CURRENT RUN WEAKENS AND ALMOST DISSIPATES THIS FEATURE
BEFORE IT REACHES THE ISLANDS. THE PRESENT FORECAST DOES NOT CALL
FOR A CHANCE OF HEAVY SHOWERS...BUT THAT POSSIBILITY MAY BE ADDED IN
THE FORECAST PACKAGE FOR TOMORROW AFTERNOON IF THE UPPER LOW IS
FAVORED AGAIN IN THE MODELS. THE 24 HOUR WAIT WILL LET US GET A
BETTER FEEL ON THE CHANCES OF HEAVY PRECIPITATION.

&&

.AVIATION...
AIRMET TANGO REMAINS IN EFFECT FOR TEMPO MODERATE AND ISOLATED
SEVERE LOW-LEVEL TURBULENCE IN THE AIR SPACE BELOW 7 KFT LEEWARD OF
THE MOUNTAINS ON ALL ISLANDS. THESE CONDITIONS WILL LIKELY CONTINUE
THROUGH TONIGHT. EXPECT VFR CONDITIONS TO PREVAIL ACROSS MOST OF THE
STATE TONIGHT AND EARLY FRIDAY. HOWEVER...BRIEF MVFR CONDITIONS DUE
TO LOW CEILINGS AND REDUCED VISIBILITIES AS LOW CLOUDS AND SHOWERS
CARRIED BY THE LOW-LEVEL TRADE WIND FLOW OCCASIONALLY AFFECT THE
WINDWARD FACING TERRAIN ON THE ISLANDS FROM TONIGHT INTO EARLY
FRIDAY MORNING.

&&

.MARINE...
MODERATE TO BRISK TRADE WINDS WILL LIKELY PERSIST THROUGH SUNDAY
NIGHT OVER THE WINDIER AREAS BETWEEN OAHU AND THE BIG ISLAND. A
SMALL CRAFT ADVISORY FOR THESE AREAS IS IN EFFECT FOR BOTH WINDS AND
SEAS. OTHER COASTAL WATERS WILL APPROACH ADVISORY CRITERIA AT
TIMES...ESPECIALLY FROM TONIGHT INTO FRIDAY.

A NORTHWEST SWELL WILL PUT BELOW ADVISORY SURF ALONG NORTH FACING
SHORES. SURF WILL REMAIN ROUGH AND CHOPPY ALONG EAST-FACING
SHORES...BUT HEIGHTS ARE EXPECTED TO REMAIN BELOW ADVISORY LEVEL.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY THROUGH FRIDAY AFTERNOON FOR THE BIG ISLAND SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST MONDAY FOR KAIWI PAILOLO AND
ALENUIHAHA CHANNELS...MAALAEA BAY AND WATERS SOUTH OF THE BIG
ISLAND.

&&

PUBLIC/MARINE...POWELL
AVIATION...HOUSTON