Flash Flood Warning 49, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
910 AM HST THU MAR 9 2006

.SYNOPSIS...
THE THREAT OF HEAVY RAINFALL AND THUNDERSTORMS WILL CONTINUE THROUGH
THE DAY FRIDAY AS A SURFACE TROUGH LINGERS WEST OF KAUAI. EAST
SOUTHEAST WINDS WILL GRADUALLY BECOME EAST NORTHEAST TRADES BY
SUNDAY AS THE TROUGH MOVES AWAY...STARTING A PERIOD OF DRIER WEATHER
WHICH WILL LAST THROUGH THE REST OF THE FORECAST PERIOD.

&&

.DISCUSSION...
DEEP SOUTHEAST TO SOUTH FLOW ASSOCIATED WITH A DEEP LAYER LOW NEAR
35N 175W IS LOCKED OVER THE MAIN HAWAIIAN ISLANDS...WITH A
CONVERGENT LOW LEVEL FLOW PRODUCING EXTENSIVE AREAS OF RAIN...WITH
EMBEDDED HEAVY SHOWERS AND THUNDERSTORMS. AN ESPECIALLY LARGE AREA
OF CONVECTION IS SEEN ABOUT 40 TO 100 MILES SOUTH OF KAUAI THIS
MORNING MOVING NORTH NEAR 20 MPH...WITH A SOLID LINE OF
THUNDERSTORMS NOTED AT ITS LEADING EDGE. WATER VAPOR IMAGERY
HIGHLIGHTS A SHORT WAVE TROUGH AXIS ALONG 165W NEAR 22N...WHICH MAY
BE HELPING TO INCITE THIS CONVECTION...AND MAY PLAY A ROLE IN
SHORT TERM CONVECTIVE EVOLUTION OVER THE WESTERN ISLANDS TODAY AND
TONIGHT. CONVECTION OVER AND NEAR THE BIG ISLAND /ALL ISLANDS
ACTUALLY/ EXTENDS THROUGH A GOOD DEPTH OF THE TROPOSPHERE...WITH
WINTRY WEATHER OCCURRING ON THE HIGHEST SLOPES OF MAUNA KEA AND
MAUNA LOA. A WINTER WEATHER ADVISORY HAS BEEN ISSUED.

ALTHOUGH THE PARENT LOW TO THE NORTHWEST IS PROGGED TO MOVE RAPIDLY
NORTH OVER THE NEXT 24 TO 36 HOURS...A LINGERING LOW LEVEL TROUGH IS
EXPECTED TO REMAIN IN PLACE JUST WEST OF KAUAI...WITH THE MOST
AGGRESSIVE GFS DEVELOPING A SURFACE LOW ALONG THE TROUGH AXIS...WITH
THE LOW MOVING NORTH. REGARDLESS OF THE DETAILS...THE TROUGHING WEST
OF THE ISLANDS WILL CONTINUE TO PROVIDE LOW LEVEL MOISTURE
CONVERGENCE OVER THE ISLANDS...ESPECIALLY OVER THE WESTERN ISLANDS.
THIS WILL CONTINUE OVER MOST AREAS THROUGH FRIDAY...ALTHOUGH KAUAI
MAY STILL BE THREATENED WITH HEAVY RAIN INTO SATURDAY. THE
LOW/TROUGH WEAKENS AND MOVES WEST LATER THIS WEEKEND...ALLOWING FOR
A DRYING TREND.

LONGER RANGE PROGS INDICATE STEADY TRADES...BUT NO SIGNIFICANT RAIN
MAKERS AFTER THIS WEEKEND. HOWEVER...A STRONG STABILIZING RIDGE IS
NOT SEEN...SO TRADES WILL LIKELY BRING A FEW WINDWARD SHOWERS...BUT
NOT AS INTENSE OR AS WIDESPREAD AS CURRENTLY.

&&
MARINE...
A HIGH SURF ADVISORY HAS BEEN ISSUED FOR EAST FACING SHORES DUE TO
THE PRESENCE OF STRONG WINDS OFFSHORE TO THE EAST PRODUCING SEAS AND
SWELLS THAT WILL RESULT IN SURF EXCEEDING ADVISORY CRITERIA.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH...ALL HAWAIIAN ISLANDS THROUGH 6 AM FRIDAY.
SMALL CRAFT ADVISORY FOR STRONG E/SE WINDS BIG ISLAND SOUTHEAST...
BIG ISLAND WINDWARD...MAUI WINDWARD...OAHU WINDWARD...KAUAI WINDWARD
WATERS THROUGH FRIDAY AFTERNOON.
WINTER WEATHER ADVISORY...BIG ISLAND SUMMITS THROUGH 6 AM FRIDAY.

&&

BIRCHARD