000
FXHW60 PHFO 182018
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST THU MAR 18 2010
.SYNOPSIS...
AN AREA OF HIGH PRESSURE NORTHWEST OF THE STATE WILL MOVE EAST
THROUGH THE REST OF THE WEEK. THIS WILL BRING MODERATE TRADES TO
THE ISLANDS. SHOWERS WILL FOCUS OVER WINDWARD AND MOUNTAIN SLOPES
THROUGH THIS WEEKEND...WITH A FEW SHOWERS BEING BLOWN LEEWARD. A
WEAK TROUGH DEVELOPS WEST OF THE ISLANDS SUNDAY AND MONDAY...CAUSING
THE WINDS TO BECOME SOUTHEASTERLY.
&&
.DISCUSSION...
THE AREA IS STILL DEALING WITH THE EFFECTS OF A COLD FRONT WHICH HAS
NOW PASSED JUST EAST OF THE BIG ISLAND. LOW LEVEL COLD AIR
ADVECTION HAS KEPT LOW CLOUDS AND SHOWERS BANKED UP AGAINST THE
WINDWARD SIDES OF THE ISLANDS. CONSIDERABLE PRECIPITATION HAS BEEN
MEASURED AT MANY WINDWARD RAIN GAGES...SOME RAIN AMOUNTS IN PAST 6
HOURS ARE...1.83 INCHES AT WEST WAILUAIKI...1.43 INCHES AT PUNALUU
STREAM...1.11 AT HANA...AND 1.02 AT HONOKAA. IN CONTRAST...THE RAIN
IS BEING EFFECTIVELY CUT OFF ON THE LEEWARD SIDES...WHERE MOSTLY
SUNNY CONDITIONS PREVAIL. THIS PATTERN WILL CONTINUE THROUGH THE
DAY...WITH SOME IMPROVEMENT IN CONDITIONS FOR WINDWARD KAUAI AND
OAHU LATER IN THE DAY. THE AREA OF HIGH PRESSURE FAR NORTHWEST OF
THE REGION IS BRINGING MODERATE NORTHEASTERLY WINDS IN ACROSS THE
ISLANDS...LOCAL GUSTS REACHING NEAR 30 MPH IN THE WINDIEST LEEWARD
AREAS AND ALONG THE EXPOSED HEADLANDS. EARLIER BOUT OF WESTERLY
WINDS ON THE BIG ISLAND SUMMITS HAS DECREASED AND THE WIND ADVISORY
WAS DISCONTINUED THERE.
THE HIGH TO THE NORTHWEST WILL CONTINUE TO MOVE EASTWARD OVER THE
NEXT FEW DAYS BRINGING MODERATE TRADES TO THE ISLANDS. WINDWARD
SHOWERS WILL BECOME MORE SCATTERED AS THE COLD AIR ADVECTION FADES.
THE PATTERN WILL REMAIN PROGRESSIVE OVER THE WEEKEND AS THE HIGH
MOVES AWAY TO THE EAST...A WEAK TROUGH DEVELOPS JUST WEST OF THE
ISLANDS SUNDAY AND MONDAY. THE TRADES WILL VEER TO THE SOUTHEAST
AND BECOME LIGHT. AT UPPER LEVELS...A 500 MB TROUGH MOVES OVER THE
SURFACE TROUGH HAVING A DESTABILIZING EFFECT AND BRINGING THE
POTENTIAL FOR HEAVIER SHOWERS. LOCATION OF THE SURFACE TROUGH WILL
BE KEY AS TO WHETHER THE HEAVIER SHOWERS THREATEN THE ISLANDS OR
REMAIN JUST TO THE WEST. THE SITUATION WILL BEAR WATCHING AS THE
VARIOUS MODELS CONTINUE TO BRING DIFFERENT SOLUTIONS FOR NEXT WEEK.
&&
.MARINE...
A NORTHWEST SWELL IS EXPECTED TO ARRIVE TONIGHT...BRINGING
NEAR ADVISORY LEVEL SURF THROUGH FRIDAY. A SOUTH SWELL IS FORECAST
TO ARRIVE SATURDAY...PRODUCING SURF NEAR OR ABOVE THE ADVISORY
THRESHOLD ALONG SOUTH FACING SHORES.
NORTHEAST WINDS OF 25 KNOTS HAVE FILLED IN BEHIND THE COLD FRONT
OVER THE PAILOLO AND ALENUIHAHA CHANNELS AS WELL AS MAALAEA BAY...SO
THE SMALL CRAFT IS IN EFFECT THERE TODAY. THE NEW NORTHWEST
SWELL...COMBINED WITH WAVES DRIVEN BY RESURGING
TRADE WINDS...WILL PUSH COMBINED SEAS IN THE COASTAL
WATERS ABOVE THE 10 FEET THRESHOLD FOR SMALL CRAFT ADVISORY
CONDITIONS THROUGH THE REST OF THE AREA. THUS...A SMALL CRAFT
ADVISORY WILL BE IN EFFECT FOR THE REST OF THE LOCAL WATERS AND
CHANNELS AS OF 6 PM HST THIS EVENING.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PAILOLO AND ALENUIHAHA CHANNELS AND FOR
MAALAEA BAY THROUGH 6 AM SATURDAY.
SMALL CRAFT ADVISORY FOR ALL COASTAL WATERS FROM 6 PM TODAY THROUGH
6 AM SATURDAY.
&&
$$
BRENCHLEY
