Drought in Hawaii, May 1 to 31, 2016

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
834 PM HST SAT APR 30 2016

.SYNOPSIS...
TRADE WIND SPEEDS ARE EXPECTED TO STRENGTHEN THROUGH SUNDAY AS
HIGH PRESSURE BUILDS FAR NORTH OF THE ALOHA STATE. MODERATE TO
LOCALLY BREEZY TRADE WINDS WILL PERSIST ACROSS THE ISLANDS
THROUGH THE MIDDLE OF NEXT WEEK. CLOUDS AND SHOWERS CARRIED BY
THE TRADES WILL CONTINUE TO FAVOR WINDWARD AND MAUKA SECTIONS.
THERE MAY BE AN INCREASE IN TRADE SHOWER COVERAGE AROUND
WEDNESDAY. A LATE SEASON FRONT IS EXPECTED TO APPROACH THE
ISLANDS FROM THE NORTHWEST LATE NEXT WEEK...WHICH MAY WEAKEN THE
TRADE WINDS NEXT WEEKEND.

&&

.DISCUSSION...
A FRONT LOCATED ABOUT 370 MILES MILES NORTH OF LIHUE HAS
TEMPORARILY WEAKENED THE PRESSURE GRADIENT ACROSS THE MAIN
HAWAIIAN ISLANDS THIS WEEKEND. HOWEVER...A 1030 MB SURFACE HIGH
CENTERED NEAR 36N 167W...OR ABOUT 1040 MILES NORTH-NORTHWEST OF
LIHUE...IS GRADUALLY BUILDING AS IT MOVES SLOWLY TOWARD THE EAST.
AS THE FRONT WEAKENS LATER TONIGHT AND SUNDAY...EXPECT THE
PRESSURE GRADIENT ACROSS THE REGION TO TIGHTEN ONCE AGAIN. AS A
RESULT...TRADE WIND SPEEDS ARE FORECAST TO REBOUND AGAIN STARTING
SUNDAY.

ALOFT...MID-TROPOSPHERIC RIDGING AND UPPER LEVEL SUBSIDENCE ARE
MAINTAINING STABLE ATMOSPHERIC CONDITIONS ACROSS THE MAIN HAWAIIAN
ISLANDS EARLY THIS EVENING. PATCHES OF LOW CLOUDS AND LIGHT
SHOWERS ARE EVIDENT IN SATELLITE IMAGERY ACROSS PARTS OF THE STATE.
THESE LOW CLOUDS AND SHOWERS ARE MAINLY AFFECTING WINDWARD FACING
SLOPES AND HIGHER TERRAIN.

THE FORECAST MODELS CONTINUE TO SHOW SURFACE HIGH PRESSURE
REMAINING NORTH OR NORTHEAST OF THE REGION THROUGH EARLY NEXT
WEEK. THE RESULTING TIGHT PRESSURE GRADIENT WILL MAINTAIN
MODERATE TO LOCALLY BREEZY TRADE WINDS ACROSS THE STATE. A MID-
TROPOSPHERIC RIDGE WILL ALSO KEEP STABLE ATMOSPHERIC CONDITIONS
ACROSS THE ISLANDS THROUGH MID-WEEK. THEREFORE...EXPECT THE SAME
GENERAL TRADE WIND SHOWER PATTERN TO CONTINUE FOR THE NEXT FEW
DAYS. HOWEVER...BY MID-WEEK ENHANCED LOW LEVEL MOISTURE ASSOCIATED
WITH THE OLD FRONT MAY REACH THE ISLANDS. IF SO...EXPECT
INCREASING TRADE SHOWER COVERAGE...ESPECIALLY ACROSS WINDWARD AND
MAUKA SECTIONS OF THE ISLAND CHAIN...AROUND WEDNESDAY.

THE MODEL OUTPUT CONTINUES TO SHOW A LATE SEASON FRONT APPROACHING
THE ISLANDS FROM THE NORTHWEST TOWARD THE END OF THE NEW WORK
WEEK. THE 0000 UTC GFS AND 1200 UTC ECMWF MODEL RUNS APPEAR TO
BRING THIS FEATURE MUCH CLOSER TO KAUAI. HOWEVER...SINCE THERE
HAVE BEEN RUN-TO-RUN VARIATIONS IN THE MODELS...WE ARE KEEPING A
TRADE WIND WEATHER REGIME IN THE FORECASTS AS WE HEAD INTO NEXT
WEEKEND. HOWEVER...IF THE FRONT IS CLOSER THAN EXPECTED...WE MAY
HAVE TO INDICATE WEAKER TRADES...AND POSSIBLY MOVE TOWARD A LIGHT
SOUTHEASTERLY FLOW PATTERN FOR NEXT WEEKEND.

&&

.AVIATION...
HIGH PRESSURE NORTH OF THE STATE WILL KEEP A MODERATE TO BREEZY
TRADE WIND FLOW IN PLACE THROUGH SUNDAY...WITH CLOUDS AND SHOWERS
FOCUSED PRIMARILY ACROSS WINDWARD AND MAUKA AREAS. MAINLY VFR
CONDITIONS ARE EXPECTED AT THE TERMINALS...BUT BRIEF MVFR
CIGS/VSBYS MAY IMPACT PHLI OR PHTO IN PASSING SHRA.

NO AIRMETS ARE CURRENTLY IN EFFECT. AIRMET TANGO WILL LIKELY BE
NEEDED FOR LOW LEVEL TURBULENCE OVER AND SOUTH THRU WEST OF THE
MOUNTAINS ON SUNDAY.

&&

.MARINE...
TRADE WINDS ARE FORECAST TO INCREASE LATER TONIGHT AND SUNDAY...
SO THE SMALL CRAFT ADVISORY /SCA/ HAS BEEN EXPANDED TO COVER THE
TYPICALLY WINDY WATERS ADJACENT TO THE ISLANDS OF MAUI COUNTY AND
THE BIG ISLAND. SCA CONDITIONS WILL LIKELY CONTINUE FOR THESE
WATERS THROUGH THE MIDDLE OF NEXT WEEK.

A REINFORCING SMALL NORTHWEST SWELL ARRIVING LATER TONIGHT IS
EXPECTED TO PEAK SUNDAY...THEN SLOWLY LOWER EARLY NEXT WEEK. A NEW
SMALL LONGER PERIOD WEST-NORTHWEST SWELL IS EXPECTED ON WEDNESDAY
AND THURSDAY. ELSEWHERE...EXPECT A NOTICEABLE BUMP IN SURF HEIGHTS
ALONG SOUTH FACING SHORES FROM THIS WEEKEND THROUGH EARLY NEXT
WEEK. STRENGTHENING TRADE WINDS WILL PRODUCE SLIGHTLY ELEVATED
ROUGH SURF CONDITIONS ALONG WINDWARD BEACHES AND REEFS ACROSS THE
STATE THROUGH MID-WEEK. HOWEVER...SURF IS EXPECTED TO REMAIN BELOW
THE HIGH SURF ADVISORY CRITERIA.

&&
.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 AM HST MONDAY FOR MAALAEA BAY...THE
WATERS SOUTH OF THE BIG ISLAND...AND THE PAILOLO AND ALENUIHAHA
CHANNELS.

&&

DISCUSSION/MARINE...HOUSTON
AVIATION...JELSEMA