| Current Conditions | ||
| Temp |  | 3.8 C |
| RH | | 76 % |
| Wind | | N 8 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 401 FXHW60 PHFO 271951 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1000 AM HST FRI FEB 27 2015 .SYNOPSIS... A SURFACE TROUGH NEAR OAHU WILL SLOWLY DRIFT EASTWARD ACROSS THE CENTRAL PART OF THE STATE THROUGH TOMORROW...DISRUPTING THE TRADE WIND FLOW AND ACTING AS A FOCUS FOR CLOUDS AND SHOWERS. AN UPPER LEVEL TROUGH LINGERING OVER THE STATE WILL MAINTAIN A CHANCE OF LOCALLY HEAVY SHOWERS NEAR THE TROUGH...MAINLY DURING THE AFTERNOON HOURS AS SEA BREEZES DRIVE CONVECTION. TRADE WINDS WILL ON SUNDAY AND CONTINUE INTO NEXT WEEK...ALTHOUGH THE WET AND UNSETTLED WEATHER PATTERN WILL LIKELY CONTINUE. && .DISCUSSION... THE CENTRAL ISLANDS ARE EXPECTED TO BE THE FOCUS FOR AFTERNOON SHOWERS TODAY...SOME HEAVY WITH A SLIGHT CHANCE OF THUNDERSTORMS. A NORTH-SOUTH ORIENTED SURFACE TROUGH...ARGUABLY THE TAIL END OF A FRONT...CURRENTLY CROSSES OAHU...AND ALTHOUGH OVERNIGHT LAND BREEZES HAVE KEPT OAHU RATHER QUIET...SCATTERED SHOWERS...SOME HEAVY...ARE OBSERVED OFFSHORE. THE SURFACE TROUGH WILL DRIFT EASTWARD TO MAUI COUNTY LATER TODAY...KEEPING WINDS LIGHT AND VARIABLE ACROSS THE CENTRAL ISLANDS AND POOLING LOW LEVEL MOISTURE NEAR OAHU AND MAUI COUNTY. DAYTIME SEA BREEZES WILL TAP THIS MOISTURE...PRODUCING CLOUDS AND SHOWERS. ALOFT...THE ISLANDS LIE UNDER THE EXIT REGION OF A JET STREAM AND THE SOUTHEAST PORTION OF A MID LEVEL TROUGH. INSTABILITY CREATED BY THESE FEATURES WILL BE ENOUGH TO SUPPORT LOCALIZED HEAVY SHOWERS...ALONG WITH A SLIGHT CHANCE OF THUNDERSTORMS FOR OAHU. ELSEWHERE ACROSS THE STATE TODAY...AVAILABLE MOISTURE WILL BE SOMEWHAT LIMITED. A DRIER NORTHERLY FLOW WITH DEW POINTS DOWN SEVERAL DEGREES HAS DEVELOPED NEAR KAUAI TO THE WEST OF THE SURFACE TROUGH. SOME AFTERNOON CONVECTION IS EXPECTED...BUT IT SHOULD BE WEAKER WITH FEWER SHOWERS. ON THE BIG ISLAND...A SOUTHEASTERLY FLOW IS PRODUCING LITTLE IN THE WAY OF SHOWERS THIS MORNING...BUT THERE IS ENOUGH MOISTURE TO PRODUCE WIDESPREAD AFTERNOON CLOUDS WITH SOME SHOWERS ON THE SLOPES. UNSETTLED WEATHER WILL LIKELY CONTINUE ACROSS THE STATE THROUGH THE WEEKEND. THE MID/UPPER LEVEL TROUGH WILL REMAIN NEARBY... MAINTAINING COLD TEMPERATURES ALOFT...WHILE THE LOW LEVEL TROUGH WILL ALSO LINGER OVER THE STATE THROUGH AT LEAST SATURDAY NIGHT... PROVIDING A FOCUS FOR SHOWERS...SOME OF WHICH WILL LIKELY BE HEAVY AT TIMES FROM OAHU THROUGH THE BIG ISLAND. ISOLATED THUNDER WILL REMAIN A POSSIBILITY AS WELL. GUIDANCE HAS TRENDED DRIER FOR KAUAI THROUGH THE WEEKEND...WITH THE LATEST GFS AND ECMWF SHOWING PWATS BELOW ONE INCH. THEREFORE HAVE SCALED BACK POPS THERE AND REMOVED MENTION OF HEAVY RAIN. MODEL CONSENSUS SUGGESTS THAT THE LOW LEVEL TROUGH WILL FINALLY WASH OUT BY SUNDAY...WITH WET TRADES DEVELOPING ACROSS THE STATE AS THE AREA OF ENHANCED MOISTURE CURRENTLY SEVERAL HUNDRED MILES ESE OF THE BIG ISLAND SHIFTS WESTWARD OVER THE AREA. MODELS HAVE COME INTO BETTER AGREEMENT FOR EARLY NEXT WEEK... WITH THE GFS FALLING INTO LINE WITH THE EC IN SHOWING JUST A VERY SUBTLE TROUGH DRIFTING WEST OVER THE STATE...AND A WET TRADE WIND PATTERN CONTINUING. THE GFS AND ECMWF FINALLY BRING A DRIER AND BREEZY TRADE WIND PATTERN ACROSS THE STATE TOWARD THE END OF NEXT WEEK. && .AVIATION... A SURFACE TROUGH SITS OVER OAHU THIS MORNING AND WILL SLOWLY MOVE EAST TO MAUI COUNTY TODAY. AS OF 19Z...SCATTERED SHOWERS ARE MAINLY FOCUSED ALONG THE TROUGH...IN THE COASTAL WATERS NORTH AND SOUTH OF OAHU. THESE SHOWERS LIKELY CARRY MVFR CIGS/VIS WITH POTENTIAL ISOL IFR. CLOUD TOPS ARE GENERALLY BETWEEN 100 AND 150 WITH SOME TOPS REACHING ABOVE FL220. LIGHTNING ACTIVITY THIS MORNING REMAINS APPROX 175 NM NORTH OF PHNL. CONDITIONS MAY BE CONDUCIVE FOR INTERIOR CONVECTION...AND THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER OAHU THIS AFTERNOON. AS THE TROUGH SHIFTS EAST...EXPECT SHOWER ACTIVITY TO INCREASE OVER MAUI COUNTY. OVER THE BIG ISLAND...EXPECT THE CLEAR MORNING SKIES TO CLOUD UP ALONG THE SLOPES THIS AFTERNOON. HOWEVER...VFR IS FORECAST TO REMAIN. SHOWER ACTIVITY WILL BEGIN TO INCREASE LATER THIS EVENING AND TONIGHT ALONG THE NORTH AND EAST SECTIONS ON THE BIG ISLAND. FOR KAUAI...EXPECT PREVAILING VFR TODAY...WITH PASSING ISOLATED SHOWERS. && .MARINE... WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS ACROSS THE COASTAL WATERS TODAY AS A TROUGH LINGERS OVER THE AREA. STRONGER N/NE WINDS WILL BUILD BACK INTO THE WESTERN SECTIONS AROUND KAUAI TONIGHT AND SATURDAY...THEN INCREASED TRADES WILL SPREAD ACROSS THE ENTIRE STATE SUNDAY INTO EARLY NEXT WEEK. THERE IS SOME CHANCE THAT ADVISORY WINDS MAY OCCUR AROUND KAUAI AS EARLY AS SATURDAY NIGHT OR SUNDAY. SCA CONDITIONS WILL BE POSSIBLE IN THE TYPICALLY WINDY AREAS AROUND MAUI COUNTY AND THE BIG ISLAND AS WELL SUNDAY INTO MONDAY. EASTERLY SWELL AROUND 5 FT 11 SECONDS WILL REMAIN THE DOMINANT SOURCE OF SEAS ACROSS MOST AREAS TODAY...THOUGH FRESH NORTHERLY WINDS DEVELOPING AROUND KAUAI WILL LEAD TO LARGER SEAS AROUND THE GARDEN ISLE. SURF ALONG EAST FACING SHORES WILL STAY BELOW HIGH SURF ADVISORY LEVELS AS THE EAST SWELL WILL GRADUALLY DECLINE THROUGH SATURDAY. SURF ALONG NORTH FACING SHORES WILL REMAIN LOW THROUGH SUNDAY. A NORTH-NORTHWEST SWELL WILL PUSH NORTH SHORE SURF TO AROUND THE ADVISORY LEVEL SUNDAY NIGHT AND MONDAY. SEE THE COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST /SRDHFO/ FOR MORE DETAILS. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION/MARINE...WROE/JACOBSON AVIATION...EATON Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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