Flash Flood Warning 12, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST SUN FEB 3 2008

.SYNOPSIS...
ATMOSPHERIC CONDITIONS REMAIN UNSTABLE DUE TO AN UPPER LEVEL TROUGH
WEST OF KAUAI. THE INFLUENCE OF THIS TROUGH WILL WEAKEN TUESDAY
THROUGH WEDNESDAY SO A RETURN TO NORMAL TRADE WIND WEATHER IS
EXPECTED BY MID WEEK. UNTIL THEN HOWEVER THERE IS STILL THE THREAT
OF HEAVY RAIN AND THE POSSIBILITY OF FLOODING.

&&

DISCUSSION...
THE FORECAST OF ISOLATED CONVECTION THROUGH MONDAY OR MONDAY NIGHT
LEAVES THE STATE UNDER THE THREAT OF HEAVY SHOWERS OR THUNDERSTORMS.
SINCE TRADE WINDS ARE STILL BLOWING THE AREAS MORE AFFECTED TEND TO
BE WINDWARD OR MOUNTAINS BUT HEAVY SHOWERS CAN ALSO MOVE ACROSS LEE
AREAS. ACTIVITY OVER KAUAI WANED SUNDAY EVENING BUT INSTABILITY
WILL REMAIN HIGH AND CONVECTIVE ACTIVITY COULD START AGAIN
ESPECIALLY NEAR KAUAI THROUGH MONDAY. HEAVY PRECIPITATION DURING
SUNDAY MOVED MORE SLOWLY OVER THAT ISLAND THAN THE OTHER SMALLER
ISLANDS HENCE THE CONTINUED CONCERN FOR FLOODING THERE. THE EASTERN
BIG ISLAND IS BEING CLOSELY MONITORED FOR ANY INCREASE SINCE
SATURATED GROUND... CONTINUING PRECIPITATION SUNDAY AND PROBLEMS
REMAINING FROM SATURDAY LEAVE THEM SUSCEPTIBLE FOR ADDITIONAL
FLOODING. SUNDAY EVENING PRECIPITATION ACTIVITY ON RADAR HAS SHOWN
SOME INCREASE OVER THE PUNA TO SOUTH POINT AREA... AND A SMALLER
INCREASE OVER HAMAKUA DISTRICT.

LITTLE CHANGE EXPECTED IN PREVIOUS FORECAST PACKAGE.

&&

.PREV DISCUSSION 4 PM...
A JET STREAM FLOWING ALONG THE SOUTHEAST FLANK OF THE UPPER TROUGH
IS MAINTAINING UNSTABLE CONDITIONS... THE UPPER TROUGH WILL BEGIN TO
DRIFT EASTWARD LATE TONIGHT AND MONDAY...WHILE THE JET STREAM MOVES
LITTLE. AS A RESULT...HEAVY SHOWERS AND A CHANCE FOR THUNDERSTORMS
WILL PERSIST STATE-WIDE...AND THE FLASH FLOOD WATCH HAS BEEN
EXTENDED THROUGH MONDAY AFTERNOON.

DEEP MOISTURE ASSOCIATED WITH THE UPPER TROUGH WILL MAINTAIN THE
THREAT FOR ADDITIONAL SNOWFALL ON THE BIG ISLAND SUMMITS TONIGHT.
THE FREEZING LEVEL ON THE AFTERNOON HILO SOUNDING HAS RISEN TO 13
KFT...WITH SUMMIT TEMPS HOVERING AROUND 0C AND LIQUID WATER SEEN ON
THE SUMMIT CAMERAS. TEMPERATURES ON THE SUMMITS WILL FALL
OVERNIGHT...MAINTAINING THE POSSIBILITY OF ADDITIONAL...WET SNOW
FALL. THE WINTER WEATHER ADVISORY HAS BEEN EXTENDED THROUGH 6 AM
MONDAY.

THE POTENTIAL FOR HEAVY SHOWERS WILL CONTINUE THROUGH THE MIDDLE OF
THE WORK WEEK AS THE UPPER LEVEL TROUGH DRIFTS SLOWLY EASTWARD AND
SLOWLY WEAKENS. THE COLDEST TEMPERATURES ALOFT ASSOCIATED WITH THE
UPPER TROUGH WILL REMAIN NORTH OF THE ISLANDS AT THIS TIME...BUT
WITH 500 MB TEMPERATURES OVER THE STATE FORECAST TO RUN BETWEEN -10
TO -12 C...THE THREAT OF HEAVY SHOWERS WILL REMAIN...THOUGH SHOWER
CHANCES WILL DIMINISH SLIGHTLY. THE UPPER TROUGH WILL MOVE OFF TO
THE NORTHEAST OF THE STATE THURSDAY NIGHT AND FRIDAY...AND STABLE
RIDGING ALOFT WILL NOSE IN FROM THE WEST. THIS WILL LEAD TO
INCREASINGLY STABLE CONDITIONS DURING THE END OF THE WORK WEEK.

HIGH PRESSURE FAR NORTH NORTHEAST OF THE STATE WILL MAINTAIN
MODERATE TO LOCALLY FRESH TRADE WINDS THROUGH MID WEEK. THE HIGH
WILL DRIFT EASTWARD FOR THE NEXT FEW DAYS...BUT ITS ASSOCIATED RIDGE
WILL HOLD FIRM SEVERAL HUNDRED MILES NORTH OF THE ISLANDS. A FRONT
PASSING NORTH OF THE STATE MAY WEAKEN THE RIDGE AND OUR TRADE WINDS
SLIGHTLY ON THURSDAY...WITH MODERATE TRADES EXPECTED NEXT WEEKEND.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 600 PM HST MONDAY FOR ALL ISLANDS.

HIGH SURF ADVISORY UNTIL 600 PM HST MONDAY FOR EAST FACING SHORES OF
KAUAI OAHU MOLOKAI MAUI AND THE BIG ISLAND.

WINTER WEATHER ADVISORY UNTIL 600 AM HST MONDAY MORNING FOR BIG
ISLAND SUMMITS.

SMALL CRAFT ADVISORY UNTIL 600 PM HST MONDAY FOR MAALAEA BAY-SOUTH
BIG ISLAND WATERS-PAILOLO AND ALENUIHAHA CHANNELS.

&&

HOAG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HONOLULU HI
911 PM HST SUN FEB 03 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0245 PM     FLASH FLOOD      N WAIMEA                21.96N 159.68W
02/03/2008                   KAUAI IN KAUAI     HI   NWS EMPLOYEE

            UPSLOPE FROM WAIMEA TOWN...AT 245 PM THE MAKAWELI RIVER
            GAGE REPORTED A LEVEL OF 15.56 FEET. THIS EXCEEDS THE
            RECORD PEAK OF 15.51 FEET OBSERVED THERE ON JAN 31 1975.

&&

ELAU/HOUSTON