High Surf in Hawaii, December 12 to 13, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
845 PM HST THU DEC 11 2008

.SYNOPSIS...
AN UPPER LEVEL TROUGH JUST WEST OF KAUAI WILL MAINTAIN A MOIST AND
UNSTABLE AIR MASS ACROSS THE 50TH STATE THROUGH MOST OF THE UPCOMING
WEEKEND. WEAK HIGH PRESSURE WILL START FILLING SUNDAY INTO MONDAY
WITH THE THREAT OF HEAVY SHOWERS ENDING.

&&

.DISCUSSION...
ALTHOUGH THE SURFACE KONA LOW 850 MILES NORTH NORTHWEST OF
KAUAI...CONTINUES TO PULL AWAYS FROM THE ISLANDS...THE UPPER LEVEL
TROUGH WILL REMAIN IN PLACE OVER THE MAIN HAWAIIAN ISLANDS THROUGH
AT LEAST SATURDAY. THIS WILL KEEP THE AIR MASS MOIST AND UNSTABLE
ACROSS THE 50TH STATE WITH THE POTENTIAL FOR HEAVY SHOWERS.

AS PER THE GFS MODEL...THE FOCUS OF THE RAIN FOR TONIGHT IS
PRIMARILY MAUI COUNTY. BUT THERE ARE SIGNS THE UPPER TROUGH HAS
STARTED TO PULL WEST OR RETROGRADE...WHICH MEANS THE FOCUS MAY SHIFT
BACK TOWARD OAHU AND KAUAI COUNTIES. THE SOUTHERLY FLOW ON THE EAST
SIDE OF THIS UPPER LEVEL TROUGH CONTINUES TO DRAW RICH TROPICAL
MOISTURE FROM PAPUA NEW GUINEA TO THE HAWAIIAN ISLANDS. ON TOP OF
THIS THERE ARE SEVERAL SMALL DISTURBANCES OR SHORT WAVE TROUGHS...
EMBEDDED IN THIS UPPER LEVEL TROUGH. HENCE...FRIDAY HAS THE
POTENTIALLY FOR BEING ANOTHER ACTIVE WEATHER DAY WITH THE FOCUS BACK
ON THE WESTERN HALF OF THE STATE. THEREFORE THERE IS NO CHANGE TO
THE STATUS OF THE FLASH FLOOD WATCH THAT IS GOOD THROUGH FRIDAY
AFTERNOON. THERE IS THE POSSIBILITY THAT THIS WATCH WILL BE
EXTENDED.

IN TANDEM WITH THE RETROGRADING UPPER TROUGH...A FRONT CURRENTLY IN
THE KAUAI CHANNEL IS EXPECTED TO MOVE WEST TONIGHT. IN FACT
SOUTHERLY WINDS ARE GRADUALLY RETURNING TO KAUAI THIS HOUR.

HERE ARE SOME NOTABLE RAINFALL TOTALS ENDING AT 8 THIS EVENING FOR A
6 HOUR PERIOD AND UNLESS NOTED...24 HOURS. ON KAUAI...KAPAHI WITH
0.15 INCH. OAHU...MAUNAWILI 1.16 INCHES...24 HOUR TOTAL 10.8 INCHES.
WAIMANALO 0.84...24 HOUR TOTAL 6.49. POAMOHO...0.27...24 HOURS
10.38. ON MOLOKAI...KAMALO 0.89...24 HOURS 2.64 INCHES. LANAI CITY
0.10. ON MAUI...WAIKAPU C.C. 1.19...24 HOURS 3.21. LAHAINA 0.57...24
HOURS 2.20 INCHES. ON THE BIG ISLAND...KEALAKEKUA 1.57...24 HOURS
2.06. KAMUELA UPPER 0.75...24 HOURS 1 INCH.

THE WIND DATA FROM HALEAKALA AND THE 2 BIG ISLAND SUMMITS ARE DOWN
BELOW THE WIND ADVISORY THRESHOLD. WE WILL BE REEVALUATING THIS IN
THE NEXT FEW HOURS. MORE THAN LIKELY...THE ADVISORY WILL BE LOWERED
AT 4 AM HST FRIDAY.

MONDAY/S FORECAST LOOKS BETTER AS BOTH THE UPPER LEVEL TROUGH AND A
SURFACE TROUGH LEAVES THE MAIN HAWAIIAN ISLANDS WITH WEAK TRADES
FILLING IN. STAY TUNE...

&&

.MARINE...
A HIGH SURF ADVISORY REMAINS IN EFFECT FOR NORTH AND WEST FACING
SHORES OF KAUAI AND NIIHAU AND NORTH FACING SHORES OF OAHU. THIS
NORTHWEST SWELL WAS GENERATED BY THE KONA LOW FAR NORTH NORTHWEST OF
THE STATE. WE WILL CONTINUE TO MONITOR AND UPDATE

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH FRIDAY AFTERNOON FOR NIIHAU-KAUAI-OAHU-
MOLOKAI-LANAI-KAHOOLAWE-MAUI-KONA-SOUTH BIG ISLAND-KOHALA-BIG
ISLAND INTERIOR.

HIGH SURF ADVISORY UNTIL 6 PM HST FRIDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-OAHU NORTH SHORE-OAHU KOOLAU.

WINTER WEATHER ADVISORY UNTIL 6 AM HST FRIDAY FOR BIG ISLAND
SUMMITS.

WIND ADVISORY UNTIL 6 AM HST FRIDAY FOR HALEAKALA SUMMIT-BIG
ISLAND SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST FRIDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS.

&&

H LAU