Drought in Hawaii, December 1 to 31, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST SAT NOV 30 2013

.SYNOPSIS...
UNSTABLE ATMOSPHERIC CONDITIONS COMBINED WITH MOIST SOUTHERLY FLOW
AHEAD OF A SURFACE FRONT WEST OF KAUAI WILL CONTINUE TO BRING
PERIODS OF HEAVY SHOWERS AND THUNDERSTORMS TO KAUAI COUNTY...AND
POSSIBLY OAHU...TONIGHT AND SUNDAY. SOME OF THE THUNDERSTORMS IN THE
VICINITY OF KAUAI MAY PRODUCE STRONG DAMAGING WINDS AND HAIL THIS
EVENING. THE SOUTHERLY FLOW AHEAD OF THE FRONT WILL ALSO BRING BRIEF
SHOWERS TO MAUI COUNTY AND THE BIG ISLAND THIS WEEKEND. THE FRONT IS
EXPECTED TO WEAKEN SUNDAY NIGHT AND MONDAY...AND A MORE TYPICAL
TRADE WIND WEATHER PATTERN WILL EVENTUALLY RETURN NEXT WEEK.

&&

.DISCUSSION...
A SURFACE FRONT WEST OF KAUAI IS MOVING SLOWLY EASTWARD. A SURFACE
RIDGE EXTENDS SOUTH SOUTHWEST FROM A 1035 MB HIGH NEAR 38N 140W TO
THE BIG ISLAND. AS A RESULT...STRONG SOUTHERLY FLOW EAST OF THE
FRONT IS BRINGING AMPLE MOISTURE UP FROM THE TROPICS OVER MOST OF
THE MAIN HAWAIIAN ISLANDS EARLY THIS EVENING.

AT THE SAME TIME...THE AXIS OF A SHARP UPPER LEVEL TROUGH EXTENDS
FROM NEAR 30N 165.5W TO 18N 166W...OR ABOUT 400 MILES WEST OF LIHUE.
THIS UPPER LEVEL TROUGH IS ADVANCING EASTWARD AT ABOUT 10 MPH. THE
DYNAMIC LIFT AND COOLER TEMPERATURES ALOFT ASSOCIATED WITH THIS
ADVANCING TROUGH ALOFT IS CAUSING THE ATMOSPHERE TO BE VERY UNSTABLE
ACROSS THE WESTERN END OF THE MAIN HAWAIIAN ISLAND CHAIN. THIS
INSTABILITY COMBINED WITH THE ABUNDANT TROPICAL MOISTURE IS
PRODUCING WIDESPREAD RAINFALL WITH EMBEDDED THUNDERSTORMS IN THE
VICINITY OF KAUAI AND NIIHAU. SOME OF THE THUNDERSTORMS OVER THE
OCEAN NEAR KAUAI HAVE BEEN SEVERE DURING THE PAST FEW HOURS. AS A
RESULT...A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT FOR KAUAI
COUNTY AND SURROUNDING WATERS THROUGH MIDNIGHT. A NEW SEVERE
THUNDERSTORM WATCH MAY BE NEEDED FOR THIS AREA AFTER MIDNIGHT.

LOOKING AT RADAR REFLECTIVITIES...THERE ARE MULTIPLE NORTH NORTHEAST
TO SOUTH SOUTHWEST ORIENTED LINES OF HEAVY SHOWERS AND EMBEDDED
THUNDERSTORMS ADVANCING SLOWLY EASTWARD. HOWEVER...THE INDIVIDUAL
CELLS WITHIN THESE LINES ARE MOVING RAPIDLY TOWARD THE NORTH
NORTHEAST.

A FLASH FLOOD WATCH ALSO REMAINS IN EFFECT FOR KAUAI COUNTY AND
OAHU. AS THESE SLOW MOVING LINES OF SHOWERS AND THUNDERSTORMS
CONTINUE TO ADVANCE TOWARD KAUAI AND NIIHAU...THERE IS A
CONSIDERABLE THREAT OF TRAINING OF HEAVY SHOWERS AND THUNDERSTORMS
OVER KAUAI AND NIIHAU FROM TONIGHT INTO EARLY SUNDAY MORNING.

FOR THE MOMENT...MOSTLY CLOUDY SKIES AND ISOLATED SHOWERS ARE
AFFECTING THE REMAINDER OF THE ISLANDS FROM OAHU EASTWARD. AS THE
AREA OF SHOWERS AND THUNDERSTORMS CONTINUES TO ADVANCE EASTWARD
LATER THIS EVENING...THE THREAT FOR FLOODING WILL INCREASE ON OAHU.
ALSO...NOTE THE SOUTHERLY WINDS ACCELERATING DOWN THE STEEP SLOPES
OF THE HIGHER TERRAIN ON KAUAI AND OAHU WILL LIKELY BRING STRONG
GUSTY WINDS TO SOME NORTH AND NORTHEAST FACING AREAS.

KAUAI COUNTY AND OAHU WILL CONTINUE TO HAVE THE POSSIBILITY OF
FLOODING RAINS ON SUNDAY...AND A FLASH FLOOD WATCH REMAINS IN
EFFECT. THE REMAINDER OF THE STATE CAN EXPECT SHOWERS RIDING THE
SOUTHERLY WINDS TO BRING BRIEF MODERATE RAINFALL THROUGH SUNDAY.

THE LATEST FORECAST GUIDANCE CONTINUES TO SHOW THE UPPER LEVEL
TROUGH WILL BEGIN TO LIFT OUT TOWARD THE NORTH NORTHEAST BY SUNDAY
EVENING. THIS IS EXPECTED TO ALLOW MORE STABLE CONDITIONS TO MOVE
ACROSS THE ISLANDS. THE SURFACE FRONT IS EXPECTED TO STALL NEAR OAHU
BY MONDAY...WHERE IT WILL LIKELY WEAKEN IN PLACE. SURFACE HIGH
PRESSURE FAR NORTHEAST OF THE ISLANDS WILL GRADUALLY INCREASE THE
PRESSURE GRADIENT ACROSS THE EASTERN ISLANDS...WITH A LIGHT
NORTHERLY FLOW REMAINING IN THE VICINITY OF KAUAI. THE FRONT IS
FORECAST TO DISSIPATE TUESDAY...AND THE REMNANT MOISTURE ASSOCIATED
WITH THIS FEATURE WILL BE PUSHED WESTWARD AS TRADE WINDS BECOME
ESTABLISHED OVER THE WESTERN END OF THE ISLAND CHAIN.

THE FORECAST MODELS INDICATE THE SURFACE HIGH WILL REMAIN FAR
NORTHEAST OF THE ALOHA STATE NEXT WEEK DUE TO ANOTHER COLD FRONT
MOVING INTO THE CENTRAL NORTH PACIFIC OCEAN FAR NORTHWEST OF THE
STATE. THE PRESSURE GRADIENT SOUTH AND SOUTHWEST OF THE HIGH WILL
MAINTAIN LIGHT TO MODERATE TRADE WINDS DURING THE SECOND HALF OF THE
NEW WEEK. SOUTHEAST WINDS ARE FORECAST TO RETURN NEXT WEEKEND WITH
ANOTHER ROUND OF INCREASED MOISTURE AND THE POTENTIAL FOR VOLCANIC
HAZE TO BE CARRIED UP OVER THE SMALLER ISLANDS.

&&

.AVIATION...
THERE IS A HIGH POTENTIAL FOR MVFR COND...MTN OBSC...TURBULENCE...
AND LIGHT ICING ACROSS KAUAI AND THE SURROUNDING WATERS TONIGHT...AS
A SLOW MOVING LINE OF LAYERED CLOUDS AND SCATTERED THUNDERSTORMS.
SIGMET VICTOR SERIES COVER THE MAIN IMPACT AREAS AT THIS TIME...BUT
AIRMETS FOR MTN OBSC...MOD TURB AND LIGHT ICING ACROSS KAUAI AND ADJ
WATERS WILL LIKELY REMAIN THROUGH THE NIGHT. UPPER TROF TO THE WEST
WILL SLOWLY BEGIN PUSHING THE SYSTEM EAST EARLY IN THE MORNING AND
THROUGH THE DAY SUNDAY. BREEZY SOUTH WINDS WILL CONTINUE ACROSS
KAUAI TONIGHT...WEAKENING SOMETIME SUNDAY.

&&

.MARINE...
A SMALL CRAFT ADVISORY /SCA/ REMAINS IN EFFECT THROUGH EARLY SUNDAY
MORNING FOR THE WATERS SURROUNDING KAUAI AND THE BIG ISLAND DUE TO
STRONG WINDS AND ELEVATED ROUGH SEAS. THE SCA MAY NEED TO BE
EXTENDED INTO SUNDAY FOR SOME HAWAIIAN WATERS IF THE WINDS AND SEAS
REMAIN HIGHER THAN CURRENTLY FORECAST.

THE CURRENT NORTHWEST SWELL WILL CONTINUE TO GRADUALLY LOWER FROM
TONIGHT THROUGH SUNDAY. A SMALL SOUTH SOUTHWEST SWELL WILL PRODUCE A
SMALL BUMP IN SURF ALONG SOUTH FACING SHORES TUESDAY AND WEDNESDAY.
EAST FACING BEACHES WILL SEE SMALL TO MODERATE SURF NEXT WEEK DUE TO
TRADE WINDS PRODUCING SOME SHORT PERIOD WIND SWELL. A MODEST
NORTHWEST SWELL IS EXPECTED TO ARRIVE WEDNESDAY...AND CONTINUE
THROUGH THE END OF THE NEW WORK WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR NIIHAU-KAUAI-OAHU.

SMALL CRAFT ADVISORY UNTIL 6 AM HST SUNDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
MAUI COUNTY WINDWARD WATERS-BIG ISLAND WINDWARD WATERS-BIG
ISLAND LEEWARD WATERS.

&&

DISCUSSION/MARINE...HOUSTON
AVIATION...FOSTER