TUTT dissipates by Friday
Posted by JAC on 7/30/2009, 9:02 am
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HONOLULU HI
955 PM HST WED JUL 29 2009

.UPDATE...
THE GRIDS AND ZONES WERE UPDATED...WITH SHOWERS BEEFED UP FOR
LEEWARD COMMUNITIES OF OAHU FOR TONIGHT AND ALL OF THURSDAY...AND
THE THE KONA COAST WITH ISOLATED SHOWERS FOR TONIGHT AND THURSDAY
NIGHT PERIODS.

&&

.SYNOPSIS...
TRADE WINDS WILL DIMINISH SLIGHTLY THROUGH THURSDAY...BUT ARE
EXPECTED TO REBUILD OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
CLOUDS AND SHOWERS WILL TEND TO FAVOR WINDWARD AND MAUKA AREAS.
AN ISOLATED THUNDERSTORM OR TWO IS POSSIBLE DURING THE AFTERNOON
HOURS THURSDAY OVER MAUI AND THE BIG ISLAND.

&&

.DISCUSSION...
THE HAWAIIAN ISLAND/S WEATHER IS UNDER THE INFLUENCE OF 2 WEATHER
FEATURES. THE FIRST IS A WELL ANCHORED...BROAD HIGH PRESSURE SYSTEM
LOCATED FAR NORTHEAST OF THE ISLANDS. IT IS PROVIDING THE ISLANDS
WITH A REFRESHING BREEZE FROM THE EAST AND NORTHEAST...ALSO KNOWN AS
THE TRADE WINDS. THE STRENGTH OF THE HIGH IS EXPECTED TO WEAKEN
DURING THE NEXT 24 HOURS RESULTING IN SLIGHTLY LIGHTER TRADES INTO
FRIDAY. THE SOURCE OF THE ISLAND/S CLOUDS AND SHOWERS IS FROM LOW
CLOUDS OFF THE CALIFORNIA COAST AND CARRIED OVER BY THE TRADE WINDS.
THE LATEST SATELLITE IMAGERY SHOWS A BROAD SOLID OVERCAST FIELD OF
STABLE LOW STRATOCUMULUS /SC/ CLOUDS WITH ITS LEADING EDGE LOCATED
800 TO 900 MILES UPWIND OF MAUI AND THE BIG ISLAND. THE FIELD
EXTEND ALL THE WAY TO SOUTHERN AND BAJA CALIFORNIA. THIS FIELD OF
SC CLOUDS TENDS TO DISPERSE BUT ALSO BECOME SLIGHTLY UNSTABLE AS IT
APPROACHES THE HAWAIIAN ISLANDS.

THE SECOND PLAYER IS AN UPPER LEVEL LOW SITUATED THIS EVENING NEAR
MAUI AND TRAVELING WESTWARD TOWARDS OAHU. THE LOW HAS TEMPERATURES
COOLER THAN NORMAL ABOVE 10000 FEET THUS FAVORING THUNDERSTORMS FOR
THE HIGHER TERRAIN SUCH AS THE BIG ISLAND SLOPES...SUMMITS AND
HALEAKALA ON MAUI. DUE TO THE LIMITED MOISTURE AT THAT HEIGHT...THE
THUNDERSTORMS ARE LIKELY DURING THE AFTERNOON HOURS OF THURSDAY.

THE LOW WILL ALSO TEND TO ENHANCE THE LOW LEVEL SHOWER BEARING
CLOUDS MOVING BENEATH IT WITH THE TOPS OF THE SHOWERS REACHING AS
HIGH AS 15 TO 20 THOUSAND FEET FROM THE TYPICAL 10 OR 12 THOUSAND
FEET. HOWEVER...AIR MASS SOUNDINGS FROM AIRCRAFT DEPARTING...
ARRIVING AT MAJOR AIRPORTS ACROSS THE STATE THIS EVENING...SHOWS A
LOW LEVEL INVERSION THAT WILL MINIMIZE THESE ENHANCED SHOWERS.

AS OF THE PAST HOUR...WEATHER RADAR IS PICKING UP PASSING SHOWERS
WITH THE WINDWARD AND MOUNTAIN AREAS RECEIVING THE BRUNT OF THEM.
SOME OF THE SHOWERS ARE MOVING INTO LEEWARD TERRITORY THANKS TO THE
STRENGTH OF THE TRADE WINDS. WEATHER RADAR IS ALSO DETECTING AN
ISOLATED SHOWER ALONG THE SOUTH KONA COAST BETWEEN KAPILO BAY AND
MILOLII.

ALL FORECAST MODELS ARE IN AGREEMENT OF THE UPPER LOW STALLING OVER
OAHU KAUAI IN THE NEXT 24 HOURS BUT ALSO WEAKENS IT WHERE IT
BECOMES LESS OR OF NO INFLUENCE ON THE ISLANDS BY FRIDAY. IN OTHER
WORDS...THE THREAT OF THUNDERSTORMS FOR THE BIG ISLAND AND MAUI
CEASES BY FRIDAY.THE MODELS ARE ALSO ON THE SAME PAGE OF STRONGER
TRADES RETURNING OVER THE WEEKEND AND PERSISTING INTO EARLY NEXT
WEEK.


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HI needs to watch 97E - JAC, 7/29/2009, 9:59 pm
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