| Current Conditions | ||
| Temp |  | 5.9 C |
| RH | | 38 % |
| Wind | | SSW 11 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 007 FXHW60 PHFO 262005 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1000 AM HST THU FEB 26 2015 .SYNOPSIS... WINDS WILL BECOME LIGHT AND VARIABLE OVER THE SMALLER ISLANDS TODAY AND SOUTHEAST AROUND THE BIG ISLAND TONIGHT...AS A SURFACE TROUGH SETTLES OVER THE STATE. THE TROUGH WILL REMAIN NEAR KAUAI AND OAHU TONIGHT THEN DRIFT EASTWARD FRIDAY AND SATURDAY. THE TROUGH WILL ACT AS A FOCUS FOR CLOUDS AND SHOWERS...AND LOCALLY HEAVY RAIN WILL BE POSSIBLE FROM FRIDAY NIGHT INTO THE WEEKEND AS THE ATMOSPHERE BECOMES INCREASINGLY MOIST AND UNSTABLE. AN UNSETTLED TRADE WIND PATTERN WILL LIKELY CONTINUE THROUGH THE WEEKEND AND MAY PERSIST INTO NEXT WEEK. && .DISCUSSION... A COMPLEX UNSETTLED WEATHER PATTERN IS SLOWLY EVOLVING OVER THE STATE. AN ERODING RIDGE ALOFT LIES OVER THE ISLANDS...WHILE A WEAK SURFACE TROUGH NEAR OAHU THIS MORNING IS DRIFTING TO THE WEST. A DEEP...NEARLY STATIONARY TROUGH IS OBSERVED TO THE NORTHWEST WITH AN ASSOCIATED FRONT SITTING ABOUT 150 MILES NORTHWEST OF KAUAI. A COMPACT UPPER LEVEL LOW AND AN ASSOCIATED SURFACE TROUGH CENTERED ABOUT 600 MILES EAST-SOUTHEAST OF HILO ARE DRIFTING TOWARD THE STATE. THESE FEATURES WILL COME TOGETHER OVER THE ISLANDS AT VARIOUS TIMES DURING THE NEXT FEW DAYS...LEADING TO AN UNSETTLED WEATHER PATTERN. FOR TODAY...THE HIGHEST CHANCES FOR SHOWERS WILL BE OVER THE SMALLER ISLANDS...ESPECIALLY OAHU...DURING THE AFTERNOON. THE ABOVE MENTIONED SURFACE TROUGH WILL BE WEAKENING...BUT IT WILL REMAIN STRONG ENOUGH TO ALTER THE BACKGROUND WIND FLOW OUT OF THE EAST- SOUTHEAST. THIS WILL LEAD TO WIDESPREAD AFTERNOON SEA BREEZES ON THE SMALLER ISLANDS THAT WILL TRIGGER INTERIOR CLOUDS AND SHOWERS... AND WITH LOW LEVEL MOISTURE REMAINING CONCENTRATED NEAR THE TROUGH...OAHU WILL HAVE THE HIGHEST CHANCES FOR SHOWERS TODAY. ALTHOUGH WEAKENING...THE RIDGE ALOFT SHOULD REMAIN STRONG ENOUGH TO INHIBIT HEAVY SHOWER DEVELOPMENT. EXPECT A DRIER EASTERLY TRADE WIND FLOW ACROSS THE BIG ISLAND. THE HIGHEST CHANCES FOR ENHANCED SHOWER ACTIVITY WILL BE OVER THE WESTERN END OF THE STATE TONIGHT AND FRIDAY. THE SURFACE TROUGH WILL WASH OUT...BUT SOME ENHANCED MOISTURE SHOULD LINGER WEST OF MAUI. THE TROUGH AND FRONT TO THE NORTHWEST OF KAUAI WILL BE WEAKENING AND PUSHING EASTWARD TO KAUAI AND OAHU AT THE SAME TIME...AND THE DIFLUENT PORTION OF THE JET STREAM ALOFT WILL BE MOVING OVER THE STATE. THIS WILL SET UP MOIST UNSTABLE CONDITIONS OVER THE WESTERN HALF OF THE STATE. HEAVY SHOWERS ARE CURRENTLY NOT INCLUDED IN THE FORECAST...BUT WE WILL HAVE TO TAKE A CLOSE LOOK AT THAT DURING THE DAY SHIFT. UNSETTLED WEATHER WILL PERSIST ACROSS PORTIONS OF THE STATE THROUGH AT LEAST THE WEEKEND. THE UPPER LEVEL TROUGH WITH COLD TEMPS ALOFT WILL REMAIN OVERHEAD...WHILE A LOW LEVEL TROUGH WILL LIKELY CONTINUE TO BE THE FOCUS FOR CLOUDS AND HEAVY SHOWERS. UNCERTAINTY REMAINS SOMEWHAT HIGH AS TO THE EXACT LOCATION OF THE TROUGH...BUT IT WILL LIKELY DRIFT FROM OAHU TO AS FAR EAST AS MAUI OR THE BIG ISLAND ON SATURDAY BEFORE WEAKENING. TO FURTHER COMPLICATE ISSUES...THE GFS IS SHOWING THE AREA OF LOW LEVEL MOISTURE...CURRENTLY 800 MILES TO THE SOUTHEAST OF THE STATE...PROVIDING A BOOST TO RAINFALL CHANCES ON SUNDAY AND MONDAY. && .AVIATION... A SURFACE TROUGH OVER OAHU THIS MORNING IS CONTINUING TO ENHANCE SHOWERS...MAINLY BETWEEN MOLOKAI AND KAUAI. AIRMET SIERRA FOR MOUNTAIN OBSCURATIONS ARE IN PLACE OVER LANAI AND N THRU E SECTIONS OF MOLOKAI...OAHU...AND KAUAI. TERMINALS...OVERALL...SHOULD REMAIN PREDOMINATELY VFR WITH ONLY POSSIBLE PERIODS OF MVFR IN SHOWERS. LOWER CLOUDS ARE LIKELY TO HANG AROUND OVER LANAI...CREATING MVFR WITH ISOL IFR CIGS THROUGHOUT THE DAY. A STALLED COLD FRONT TO THE WEST OF KAUAI AND THE SURFACE TROUGH ARE HELPING TO CREATE LIGHT EAST TO SOUTH EAST FLOW OVER THE ISLANDS...PROMOTING SEA BREEZE AND INTERIOR CLOUDS THIS AFTERNOON. && .MARINE... NO MARINE WARNINGS OR ADVISORIES ARE IN EFFECT. THE WEST-NORTHWEST SWELL CONTINUES TO DROP AT BUOY 51101...DOWN TO JUST OVER 5 FT AT 11 SECONDS AT THE LAST OBSERVATION. THIS STEADY TREND ALONG WITH A LOOK AT SURF CAMERAS NEAR KAILUA-KONA HAS LED TO THE HIGH SURF ADVISORY BEING DROPPED FOR WEST FACING SHORES OF THE BIG ISLAND. THE NEXT SWELL WITH BORDER LINE HIGH SURF ADVISORY POTENTIAL WILL BE FROM THE NORTH-NORTHWEST ON SUNDAY NIGHT AND MONDAY. A SMALL INCREASE IN FRESH...SHORT-PERIOD EASTERLY IS ALSO DUE TONIGHT AND THURSDAY WITH EAST SHORE SURF EXPECTED TO REMAIN BELOW ADVISORY LEVELS. LIGHTER WINDS WILL PREVAIL TODAY THROUGH FRIDAY AS A SURFACE TROUGH LINGERS OVER THE ISLANDS. TRADE WINDS SHOULD BUILD BACK IN ACROSS THE STATE DURING THE WEEKEND INTO EARLY NEXT WEEK...WITH SOME CHANCE THAT WINDS MAY APPROACH ADVISORY LEVELS ACROSS THE WINDIER ZONES. && .HFO WATCHES/WARNINGS/ADVISORIES... && $$ DISCUSSION/MARINE...WROE AVIATION...EATON Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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