Flash Flood Warning 5, NWS Honolulu, HI

471 
WGHW70 PHFO 080015
FFSHFO

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE HONOLULU HI
215 PM HST SAT MAR 7 2009

HIC001-080019-
/O.CAN.PHFO.FF.W.0005.000000T0000Z-090308T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
HAWAII IN HAWAII COUNTY-
215 PM HST SAT MAR 7 2009

...THE FLASH FLOOD WARNING IS CANCELLED FOR THE ISLAND OF HAWAII IN
HAWAII COUNTY...

HIGHWAY 11 BETWEEN MILE MARKERS 2 AND 4 IS OPEN...AND THE FLASH 
FLOOD ADVISORY IS NOT NEEDED.

LAT...LON 1972 15515 1973 15496 1959 15496 1959 15515

$$

CRAIG

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST SAT MAR 7 2009

.SYNOPSIS...
MODERATE TRADE WINDS WILL PERSIST INTO NEXT WEEK. A MOIST AND
UNSTABLE ATMOSPHERE WILL INTENSIFY SHOWERS...PRODUCE WIDESPREAD
LIGHT RAIN...AND ALLOW A SLIGHT CHANCE OF THUNDERSTORMS THROUGH
TONIGHT. CONDITIONS WILL BECOME SLIGHTLY LESS SOGGY ON SUNDAY...BUT
WILL REMAIN UNSETTLED THROUGH WEDNESDAY.

&&

.DISCUSSION...
A SURFACE HIGH IS LOCATED FAR NORTH OF HAWAII AND A WEAK SURFACE
TROUGH SITS JUST TO THE SOUTHWEST. THE PRESSURE GRADIENT BETWEEN THE
TWO IS BRINGING MODERATE LOCALLY STRONG TRADE WINDS TO THE ISLANDS.
LITTLE CHANGE IN THIS PATTERN IS FORECAST.

IT IS A DIFFERENT STORY HIGHER UP IN THE ATMOSPHERE WHERE THERE IS
AN UPPER LEVEL LOW JUST NORTHWEST OF KAUAI AND AN UPPER LEVEL TROUGH
NORTH OF THE STATE. COLD TEMPERATURES ALOFT ASSOCIATED WITH THE LOW
AND TROUGH HAS DESTABILIZED THE ATMOSPHERE...THUS PROMPTING THE
SLIGHT CHANCE OF THUNDERSTORMS IN THE FORECAST. THE TROUGH IS ALSO
BRINGING IN MOISTURE IN THE FORM OF MID AND HIGH-LEVEL CLOUDS...
WHICH ARE DEPOSITING INTERMITTENT LIGHT RAIN ON THE ISLANDS. LITTLE
CHANGE IS FORECAST IN THIS PATTERN AS WELL...AT LEAST THROUGH
TUESDAY. AFTER THAT...THE TROUGH MAY END UP SOUTHEAST OF HERE...
BRINGING US UNDER A DRYER AND MORE STABLE ATMOSPHERE.

IT SHOULD BE POINTED OUT THAT THE VARIOUS MODELS ARE IN POOR
AGREEMENT...ESPECIALLY REGARDING THE LOW LEVEL FEATURES. THE
FORECAST FOR THE NEXT SEVERAL DAYS MAY THEREFORE REQUIRE WHOLESALE
CHANGES. AS AN EXAMPLE...THE ECMWF MODEL PREDICTS THAT THE SURFACE
TROUGH TO THE SOUTHWEST WILL DEEPEN INTO A WELL-DEFINED LOW AND MOVE
NORTHEASTWARD ACROSS THE STATE. THIS SOLUTION...IF CORRECT...WOULD
REQUIRE CHANGING THE WIND FORECAST FOR THE BIG ISLAND TO PREVAILING
SOUTHWESTERLIES...WHILE THE REST OF THE STATE WOULD SEE NORTH TO
NORTHWEST WINDS. THE GFS MODEL...ON THE OTHER HAND...DEVELOPS A WEAK
LOW SOUTH OF THE BIG ISLAND ON MONDAY WHICH WOULD INTENSIFY THE
TRADES. WILL FORECAST PERSISTENCE FOR NOW...SUBJECT TO CHANGES LATER
ON.

CLOUDS FLOWING OVER THE SUMMITS OF THE BIG ISLAND CONTINUE TO
PRODUCE RIME ICE AND SNOW ABOVE 11000 FEET. WINDS AT UPPER
ELEVATIONS REMAIN JUST BELOW THE ADVISORY LEVEL...BUT MAY RISE
LATER IN THE WEEK IF A JET STREAM SHIFTS CLOSER TO THE SUMMITS.

&&

.MARINE...
A NORTHWEST SWELL MAY RAISE SURF HEIGHTS TO NEAR THE ADVISORY
LEVEL OF 15 FEET ALONG NORTH FACING SHORES BY EARLY MONDAY.

WINDS IN THE CHANNELS AND AROUND THE BIG ISLAND REMAIN STRONG ENOUGH
TO REQUIRE A SMALL CRAFT ADVISORY THROUGH SUNDAY EVENING.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM HST SUNDAY FOR BIG ISLAND
SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST SUNDAY FOR MAALAEA BAY-
PAILOLO AND ALENUIHAHA CHANNELS-WATERS SOUTH OF THE BIG ISLAND.

&&

CRAIG