| Current Conditions | ||
| Temp |  | -0.9 C |
| RH | | 89 % |
| Wind | | W 21 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 525 FXHW60 PHFO 190440 AAA AFDHFO AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HONOLULU HI 640 PM HST SAT MAY 18 2013 .UPDATE... INCREASED CHANCES FOR RAIN TONIGHT...ESPECIALLY THIS EVENING...ACROSS THE KONA AND KOHALA AREAS OF THE BIG ISLAND GIVEN THE CURRENT RADAR PICTURE. && .SYNOPSIS... A LOW ALOFT WILL LINGER NORTHEAST OF THE AREA THROUGH MID-WEEK... BEFORE WEAKENING AND MOVING OFF TO THE NORTH. THE LOW WILL PRODUCE LIGHT SURFACE WINDS OVER MOST AREAS AND BRING A CHANCE OF LOCALLY HEAVY SHOWERS. AS THE LOW ALOFT DEPARTS...TRADE WINDS WILL SPREAD BACK OVER THE AREA BY NEXT WEEKEND. HIGH SURF WILL CONTINUE ALONG THE SOUTH SHORES THROUGH SUNDAY...AND POSSIBLY INTO MONDAY. && .PREV DISCUSSION.../ISSUED 400 PM HST SAT MAY 18 2013/ THE GLOBAL MODELS AGREE PRETTY WELL ON THE WEATHER PATTERN THROUGH NEXT WEEK...BUT THE PATTERN IS COMPLICATED...AND IT MAY BE DIFFICULT TO PIN DOWN THE DETAILS. THE SURFACE HIGH THAT HAS BEEN BRINGING TRADE WINDS TO THE ISLANDS HAS MOVED FAR NORTHEAST OF THE ISLANDS AND THE TRADES HAVE WEAKENED TO GENTLE SPEEDS. A LOW HAS FORMED WITHIN A SHARP TROUGH ALOFT DIGGING SOUTH TOWARD THE ISLANDS. THE LOW ALOFT IS KEEPING THE ATMOSPHERE OVER THE ISLANDS UNSTABLE. CONVECTIVE SHOWERS HAVE FLARED UP OVER THE ISLANDS FROM THE BIG ISLAND TO OAHU AND ONE THUNDERSTORM BRIEFLY FORMED OVER THE SOUTHEAST SLOPES OF THE BIG ISLAND. AS THE UPPER TROUGH CONTINUES DIGGING TOWARD THE ISLANDS TODAY WE EXPECT A WEAK NORTH TO SOUTH SURFACE TROUGH OVER MAUI COUNTY TO RAPIDLY SHARPEN...WITH WINDS VEERING OUT OF THE SOUTHEAST NEAR THE BIG ISLAND...BACKING TO NORTH NORTHEAST NEAR KAUAI...AND BECOMING LIGHT AND VARIABLE AROUND OAHU AND MAUI COUNTY. TRADE-WIND-LIKE WEATHER WILL PERSIST OVER KAUAI COUNTY FOR THE NEXT DAY OR TWO. WITH LIGHTER WINDS AND MORE INSTABILITY FROM OAHU TO MAUI...A CONVECTIVE PATTERN WILL PREVAIL WITH CLOUDS AND LOCALLY HEAVY SHOWERS IN THE AFTERNOONS AND EVENINGS AND PARTIAL CLEARING OVERNIGHT. THE ATMOSPHERE WILL BE MOST UNSTABLE NEAR THE BIG ISLAND SO WE ARE FORECASTING A SLIGHT CHANCE OF THUNDERSTORMS THERE THROUGH THIS EVENING. THE SURFACE TROUGH WILL LINGER NEAR MAUI THROUGH MONDAY...THEN SLOWLY WEAKEN AND MOVE OFF TO THE WEST. ALOFT...A LOW WILL PERSIST NORTHEAST OF THE AREA THROUGH MID-WEEK. LIGHT WINDS ASSOCIATED WITH THE SURFACE TROUGH AND INSTABILITY FROM THE LOW ALOFT WILL KEEP A CONVECTIVE PATTERN OVER THE ISLANDS THROUGH WEDNESDAY OR THURSDAY. LATER IN THE WEEK...AND THE TIMING IS STILL UNCERTAIN...HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST AND TRADE WINDS WILL RETURN. THE MODELS ARE IN GOOD AGREEMENT SHOWING THE TRADE WINDS BECOMING WELL-ESTABLISHED BY FRIDAY...AND LOCALLY BREEZY NEXT WEEKEND. THE CONVECTIVE PATTERN WILL END AND THE TRADES WILL BRING SHOWERS TO WINDWARD AREAS. ANOTHER TROUGH ALOFT MAY DIG DOWN OVER THE AREA NEXT WEEKEND AND MAY ENHANCE THE WINDWARD SHOWERS. && .AVIATION... A CONVECTIVE PATTERN OVER THE ISLANDS WILL BRING LOCALLY HEAVY SHOWERS FROM THE BIG ISLAND TO OAHU OVER THE NEXT FEW DAYS WITH THUNDERSTORMS POSSIBLE OVER THE BIG ISLAND THROUGH THIS EVENING. THE GREATEST CHANCE FOR MVFR CONDITIONS AND MOUNTAIN OBSCURATION FOR THE NEXT FEW DAYS WILL BE DURING THE AFTERNOONS AND EVENINGS. && .MARINE... WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS STATEWIDE THROUGH NEXT WEEK. A SERIES OF SWELLS WILL KEEP ELEVATED SURF ALONG SOUTH SHORES THROUGH MOST OF THE UPCOMING WEEK WITH SURF EXPECTED TO REMAIN ABOVE THE ADVISORY THRESHOLD THROUGH AT LEAST SUNDAY EVENING AND PROBABLY LONGER. A MARINE WEATHER STATEMENT ALSO CONTINUES FOR WAVES BREAKING NEAR CHANNEL ENTRANCES AND POSSIBLE HARBOR SURGES. SEE THE SURF ZONE FORECAST AND COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY UNTIL 6 PM HST SUNDAY FOR SOUTH SHORES OF ALL ISLANDS. && $$ UPDATE...FOSTER PREVIOUS DISCUSSION/AVIATION/MARINE...DONALDSON Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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