000
FXHW60 PHFO 230156
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST WED FEB 22 2012

.SYNOPSIS...
WINDS WILL CONTINUE TO WEAKEN AND TURN SOUTHEAST TONIGHT THROUGH
FRIDAY. LINGERING INSTABILITY FROM AN UPPER LOW...AND LIMITED
MOISTURE WILL ALLOW FOR SOME ENHANCED SHOWERS OVER WINDWARD...
MAUKA...AND SOUTHEAST PARTS OF THE ISLANDS. INTERIOR CLOUDS AND
SHOWERS ARE POSSIBLE FRIDAY AFTERNOON WITH LIGHTER WINDS...BEFORE
MORE TYPICAL TRADE WIND WEATHER RETURNS EARLY NEXT WEEK.

&&

.DISCUSSION...
AN UPPER LEVEL LOW ABOUT 300 MI SSE OF SOUTH POINT ON THE BIG ISLAND
IS MOVING E 10 MPH. THE UPPER LOW APPEARS TO BE GRADUALLY LOSING ITS
HOLD ON OUR WEATHER...LEAVING US IN SE FLOW AT CLOUD LEVEL...AND
MODERATE TRADES AT THE SURFACE. LOW LEVEL MOISTURE IS NOT VERY
IMPRESSIVE...BUT THE AFTERNOON SOUNDINGS SHOW THAT IT IS STILL
SOMEWHAT UNSTABLE WITH AN ELEVATED INVERSION NEAR 8000 FT AT LIHUE...
AND NO APPRECIABLE INVERSION AT HILO.

AS ONE UPPER LOW MOVES OUT...ANOTHER UPPER LOW IS FORECAST TO
DEVELOP TO THE W OF THE ISLANDS THIS WEEKEND. THE MODELS ARE
STARTING TO COME INTO BETTER AGREEMENT...SHOWING THE LOW DEVELOPING
BETWEEN 170W-175W...WHICH IS LIKELY TOO FAR AWAY TO HAVE ANY
MAJOR EFFECTS ON OUR WEATHER. HOWEVER...THE NEARBY TROUGHING WILL
KEEP SE LOW LEVEL FLOW CONTINUING FOR THE NEXT FEW DAYS...AND
SOME LINGERING INSTABILITY OVER THE ISLANDS. THIS WILL MAKE FOR
SHOWERY SPELLS FOR E AND SE FACING SECTIONS...ALTHOUGH FORECASTING
THE PRECISE TIMING AND PLACEMENT OF THESE NARROW BANDS OF SHOWERS IS
CHALLENGING. ALSO...FORECAST GRIDS CONTINUE TO SHOW THE SURFACE
REFLECTION OF THE TROUGH STRONG ENOUGH TO ALLOW FOR LOCALIZED SEA
BREEZES OVER SOME AREAS ON FRI...WHICH COULD LEAD TO SOME AFTERNOON
CLOUDINESS AND LOCALIZED INTERIOR SHOWERS AS WELL.

THE UPPER LOW WILL START TO MOVE AWAY TO THE WEST THIS WEEKEND...
AND HIGH PRESSURE WILL BUILD NORTH OF THE ISLANDS. THIS SHOULD
RETURN MORE SETTLED TRADE WIND WEATHER EARLY NEXT WEEK.

&&

.AVIATION...
GUSTY TRADES AND WINDWARD SHOWERS PREVAIL THIS AFTERNOON. WINDWARD
TERMINALS ARE PULLING IN SOME MVFR/IFR OBS AT TIMES SO THERE HAVE
BEEN A FEW TAF AMENDMENTS. THIS SCENARIO WILL CONTINUE OVERNIGHT.
VFR SHOULD PREVAIL FOR THE REMAINING TERMINALS.

AIRMET SIERRA REMAINS POSTED FOR PARTS OF WINDWARD HALEAKALA/BIG
ISLAND. THIS SHOULD PERSIST FOR A WHILE SINCE CLD/SHRA EXTEND WELL E
OF THE AREA. THIS MAY BECOME PATCHY AT TIMES...HOWEVER IFR SHOULD
PREVAIL ALONG THE WINDWARD SLOPES. AIRMET TANGO MAY SPREAD TO OTHER
AREAS BASED ON CHANGES IN SHRA COVERAGE.

AIRMET TANGO WILL REMAIN POSTED FOR LOW LEVEL TURB DUE TO THE GUSTY
TRADES. AIRCRAFT ARE REPORTING SIGNIFICANT TURB ON APPROACH TO PHOG.
HAVE NOT HAD ENOUGH SIGNIFICANT LLWS PIREPS TO WARRANT ADDING IT TO
THE TAF. MAINLAND TRAFFIC MAY EXPERIENCE POCKETS OF LIGHT CHOP
BETWEEN HERE AND ABOUT 900 NM TO THE NE.

TS REMAIN ACTIVE WITH TOPS TO FL350-FL400 OVER THE FAR SE PORTION OF
HCF AIRSPACE WITHIN 180 NM OF N16 W153. ICING POTENTIAL OVER THE
IMMEDIATE FA REMAINS LOW...ALTHOUGH IS LIKELY INVOF THE
AFOREMENTIONED CONVECTION. NO SIGMET IS NECESSARY AT THIS TIME. THIS
ARE OF TS SHOULD STAY E TO SE OF THE AREA OUT OF THE PRIMARY
NORTH/SOUTHBOUND TRAFFIC AS THE LOW MEANDERS E.

&&

.MARINE...
HAVE EXTENDED THE SMALL CRAFT ADVISORY INTO THU FOR ALL EXCEPT
LEEWARD SECTIONS OF THE SMALLER ISLANDS...DUE TO WINDS NEAR THE BIG
ISLAND AND HAZARDOUS SEAS ELSEWHERE. A 21Z ASCAT PASS STILL SHOWED
UP TO 30 KT THROUGH THE ALENUIHAHA CHANNEL AND DOWNSTREAM OF
SOUTH POINT. WINDS WILL QUICKLY DROP OFF AS THEY VEER MORE SE...
BUT WILL CARRY 25 KT NEAR THE BIG ISLAND INTO THU. SEAS REMAIN
ELEVATED DUE TO THE LONG AND WIDE FETCH EXTENDING UPSTREAM OF THE
STATE. THE MOKAPU AND PAUWELA BUOYS BOTH CONTINUE TO SHOW SEAS
RUNNING ABOVE 11 FT. 18Z WAVEWATCH III GUIDANCE SHOWS THE TRADE
SWELL SLOWLY DIMINISHING THROUGH THU. SURF ALONG E FACING SHORES
WILL REMAIN ABOVE THE ADVISORY LEVEL OF 8 FT...AND THE HIGH SURF
ADVISORY HAS BEEN EXTENDED INTO THU AM.

NORTH PACIFIC SWELL WILL REMAIN ON THE MODERATE SIDE STAYING A FEW
FEET OVERHEAD OVER THE NEXT FEW DAYS. LARGER SWELL IS EXPECTED THIS
WEEKEND AND MAY GRAZE ADVISORY LEVELS SAT NIGHT AND SUN. SIGNIFICANT
MODEL DISCREPANCIES DO EXIST OVER THE NORTH PACIFIC. THIS COULD LEAD
TO FURTHER CHANGES IN THE SWELL FORECAST BEYOND FRI.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY THROUGH 10 AM HST THURSDAY FOR KAUAI
WINDWARD-OAHU KOOLAU-OLOMANA-MOLOKAI WINDWARD-WINDWARD HALEAKALA-
SOUTH BIG ISLAND-BIG ISLAND NORTH AND EAST.

SMALL CRAFT ADVISORY FOR WINDWARD WATERS...CHANNELS...AND WATERS
NEAR THE BIG ISLAND UNTIL 6 PM THURSDAY.

&&

$$

R BALLARD/DEJESUS/BRAVENDER

THE HYDROMETEOROLOGICAL PREDICTION CENTER

CAMP SPRINGS, MD

---

HAWAII EXTENDED FORECAST DISCUSSION

---

 
HAWAII EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
619 AM EST WED FEB 22 2012
 
VALID 00Z THU FEB 23 2012 - 00Z THU MAR 01 2012
 
GLOBAL MODEL GUIDANCE AGREEMENT REMAINS WORSE THAN AVERAGE IN THE
CENTRAL PACIFIC IN A SPLIT JET REGIME. THE 06Z GFS AND 00Z
GFS/CANADIAN EMPHASIZE AN UPPER LOW TO THE NORTHEAST OF HAWAII
OVER THE WEEKEND WHILE THE 00Z ECMWF/UKMET ONLY FOCUS ON ONE WEST
OF 160W THAT DRIFTS WESTWARD AND WEAKENS NEXT WEEK. THE ENSEMBLES
SUGGEST THAT THE GFS/CANADIAN ARE IN THE MINORITY AND THE 06Z RUN
APPEARS ESPECIALLY OVERDONE. FOLLOWING A 00Z ECMWF/UKMET FORECAST
WOULD KEEP THE BEST MOISTURE /PWS OVER 1.5 IN/ JUST WEST OF THE
STATE BUT SUSTAINED SOUTHEASTERLY FLOW SHOULD MEAN A BETTER CHANCE
FOR WIDESPREAD SHOWERS WITH LOCALLY HEAVY RAIN POSSIBLE IN FAVORED
AREAS. TRADES WILL SLACKEN A BIT AFTER TODAY BUT MAY PICK UP NEXT
WEEK AS HIGH PRESSURE ATTEMPTS TO REASSERT ITSELF TO THE NORTHEAST
OF THE STATE NEAR 35N/135W.


FRACASSO

---

Last Updated: 619 AM EST WED FEB 22 2012

---