Heavy Rain in Hawaii, August 12, 2002

HAWAIIAN ISLANDS SYNOPTIC DISCUSSION AND GUIDANCE
NATIONAL WEATHER SERVICE HONOLULU HI
10 AM HST MON AUG 12 2002

SUMMARY...LOW PRESSURE TO THE NORTHWEST OF HAWAII IS CAUSING
AN UNSTABLE SOUTHWESTERLY FLOW IN THE UPPER ATMOSPHERE OVER THE
ISLANDS. AT LOWER LEVELS NEAR THE SURFACE A MOIST SOUTHEASTERLY FLOW
PERSISTS. SOME LOCALLY HEAVY SHOWERS ARE POSSIBLE TODAY THROUGH
MIDWEEK PARTICULARLY OVER THE WESTERN ISLANDS OF KAUAI AND OAHU.

DISCUSSION...THE HIGH PRESSURE CELL TO THE NORTHEAST OF HAWAII WILL
BE MOVING NORTH AND NORTHWEST CAUSING THE RIDGE NORTH OF HERE TO
GET ERODED AWAY AND A LARGER SCALE INVERTED TROUGH TO DEVELOP IN ITS
PLACE FOR A FEW DAYS OVER THE LEEWARD HAWAIIAN ISLANDS FROM KAUAI TO
MIDWAY AND POINTS NORTH. SURFACE WINDS OVER THE WESTERN ISLANDS ARE
ALREADY OUT OF THE SOUTHEAST AND PRESSURES A COUPLE OF MILLIBARS
BELOW NORMAL. SEVERAL DISTURBED LOW CLOUD AND SHOWER AREAS WITHIN
THE TROPICS TO THE SOUTHEAST OF THE STATE MAY GET DRAWN UP OVER THE
ISLANDS DURING THE NEXT COUPLE OF DAYS AND CAUSE SOME LOCALLY HEAVY
RAINFALLS. SO FAR THIS MORNING ONLY KAUAI HAS BEEN AFFECTED.
INCREASED HUMIDITY AND SULTRINESS OF THE AIR MASS IS ALSO LIKELY AS
WINDS WEAKEN IN THE SOUTHEASTERLY FLOW TO THE LEE OF THE BIG ISLAND
VOLCANOS.

BY SATURDAY THE HIGH PRESSURE CELL THAT TEMPORARILY MOVED TO THE
ALASKA PENINSULA /EASTERN BERING SEA REGION WILL BE DROPPING BACK
SOUTHEASTWARD AND SOUTHWARD TO ITS USUAL LOCATION WHILE THE
UNSEASONABLE LOW TO OUR NORTHWEST MOVES NORTH TO THE ALEUTIANS.
THIS WILL ALLOW THE RIDGE NORTH OF HERE TO REFORM AND STRENGTHEN
AND USHER IN MORE NORMAL DRIER TRADE WIND WEATHER.  ROSENDAL

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