Heavy Rain in Hawaii, June 5, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST THU JUN 5 2008

.SYNOPSIS...
THE AIR MASS WILL BE SOMEWHAT UNSTABLE DUE TO AN UPPER LEVEL LOW
MOVING ACROSS THE ISLANDS TONIGHT AND FRIDAY. THERE MAY BE A FEW
HEAVY SHOWERS. TRADE WINDS WILL WEAKEN A BIT FRIDAY. A RETURN TO
MORE TYPICAL WEATHER AND MODERATE TRADES ARE EXPECTED BY THE FIRST
PART OF NEXT WEEK.

&&

.DISCUSSION...
RADAR DATA HAS BEEN RESTORED BUT A FEW FORECAST PRODUCTS MAY NOT BE
AVAILABLE ON THE INTERNET UNTIL REMAINING COMPUTER PROBLEMS ARE
REMEDIED.

A FEW RAIN GAGES OVER KAUAI AND OAHU REPORTED SEVERAL MORE TENTHS
OF AN INCH OF PRECIPITATION IN THE 6 HOURS ENDING AT 2 PM...
BUT OTHER AREAS WERE RELATIVELY DRY AFTER THE EPISODE OF MORNING
SHOWERS. THERE WERE ONE OR TWO SMALL AREAS OF HEAVY SHOWERS ON THE
LEEWARD SLOPES OF THE BIG ISLAND IN THE AFTERNOON.

THE UPPER LOW WAS 250 MILES TO THE NORTHEAST OF HILO MOVING TOWARD
OUR STATE. IT IS MOST APPARENT ON THE SATELLITE IMAGERY MOISTURE
CHANNEL. THERE WAS A LARGE SPOKE OF MID AND HIGH CLOUDS ROTATING
AROUND THE LOW ONTO THE ISLANDS. SCATTERED SHOWERS WILL MOVE ACROSS
THE ISLANDS TONIGHT AND FRIDAY ACCOMPANYING THIS UPPER LOW. THE
ASSOCIATED COOLER AIR IN THE MID ATMOSPHERE PROVIDES ADDED STRENGTH
TO SHOWERS. THE AFTERNOON BALLOON SOUNDINGS REVEAL THE DISAPPEARANCE
OF THE TEMPERATURE INVERSION WHICH WOULD OTHERWISE INHIBIT THE
VERTICAL HEIGHT OF SHOWERS. HOWEVER THE POSITION OF AN UPPER LOW
EITHER OVER THE STATE OR JUST NORTH DOES NOT PRODUCE THE STRONGEST
DYNAMICS. AFTER THE LOW MOVES WEST OF KAUAI ON SATURDAY THERE WILL
SOME REMAINING INSTABILITY RESULTING FROM THE ASSOCIATED UPPER LEVEL
SOUTHERLY FLOW. IN SUMMARY THE GENERALLY UNSETTLED CONDITIONS WITH
ISOLATED HEAVY SHOWERS ARE EXPECTED INTO SATURDAY AND POSSIBLY
SUNDAY TOO. COMPUTER MODELS HOWEVER DO NOT INDICATE SIGNIFICANT
RAINFALL AMOUNTS THROUGH THE WEEKEND AND ANY HEAVY SHOWERS WILL
LIKELY BE ISOLATED AND SHORT LIVED.

TRADE WINDS WILL TREND DOWN TO THE GENTLE TO MODERATE RANGE...SINCE
THE SURFACE RIDGE TO THE NORTH WILL BE WEAKENED BY THE PASSAGE OF
THE UPPER LOW.

THE NORMAL JUNE WEATHER PATTERN IS DOMINATED BY TRADE WIND
WEATHER... HOWEVER AFTER MONDAY THE MODELS AGREE ON SHIFTING THE
THE NORTHEAST PACIFIC HIGH FARTHER NORTHWARD AND UNDERCUTTING IT
WITH A LARGER UPPER LOW. THIS NEW UPPER LOW THEN SHIFTS TOWARD THE
ISLANDS BY MID WEEK. THIS MAY NOT MEAN ESPECIALLY WET WEATHER BUT
IF CORRECT AT LEAST IMPLIES WEAKENING TRADES AGAIN BY NEXT WEEK
THURSDAY AND FRIDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

HOAG