| Current Conditions | ||
| Temp | -0.9 C | |
| RH | 29 % | |
| Wind | W 13 mph | |
| Road | Open | |
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Hawaiian Islands Synoptic Discussion and Guidance 270 FXHW60 PHFO 190635 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 835 PM HST SAT MAY 18 2013 .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. && .DISCUSSION... A COMPLICATED WEATHER PATTERN PERSISTS ACROSS THE STATE THIS EVENING. WATER VAPOR IMAGERY SHOWS A COLD UPPER TROUGH NORTH OF THE ISLANDS DIGGING SOUTH-SOUTHEAST THIS EVENING. MEANWHILE...AT THE SURFACE...A SHARP INVERTED TROUGH HAS AN AXIS ACROSS MAUI AND IS STATIONARY. TO THE NORTH...A COLD FRONT IS LOCATED ABOUT 175 MILES AWAY FROM KAUAI AND MOVING SOUTH AT 20 MPH. THE FRONT IS OVERRUN BY BREEZY NORTHERLY WINDS ASSOCIATED WITH HIGH PRESSURE NORTH AND WEST OF THE INVERTED TROUGH. CURRENT RADAR AND INFRARED SATELLITE SHOWS A NORTH TO SOUTH ORIENTED BAND OF CLOUDS AND SHOWERS LINED UP ALONG THE WINDWARD AND SOUTHEASTERN COASTS OF THE BIG ISLAND. CLOUDS AND SCATTERED SHOWERS COVER THE BIG ISLAND AND MAUI THIS EVENING. A FEW MODERATE TO HEAVY SHOWERS REMAIN THIS EVENING FROM THE DAY/S SEA BREEZE CONVERGENCE OVER THE KOHALA AND NORTH KONA AREAS. FOR TONIGHT...EXPECTING THE CLOUDS AND SHOWERS TO WEAKEN AND DISSIPATE OVER THE ISLANDS AS THE LAND BREEZES SET IN. SOME SHOWER ACTIVITY WILL LIKELY CONTINUE INTO OVERNIGHT ACROSS BOTH WINDWARD AND LEEWARD SIDES OF THE BIG ISLAND GIVEN THE POOLED MOISTURE AROUND THE AREA. THE POTENTIAL FOR HEAVY RAINS WILL CONTINUE THROUGH THE NIGHT FOR THE BIG ISLAND. FOR TOMORROW...THE LIGHT BACKGROUND FLOW RESULTING FROM THE PRESENCE OF THE SURFACE TROUGH WILL ALLOW SEA BREEZES TO BUILD OVER THE ISLANDS AGAIN. KAUAI WILL BE THE EXCEPTION WITH MODERATE NORTHERLY WINDS. CLOUDS AND SHOWERS ASSOCIATED WITH THE APPROACHING FRONT SHOULD ARRIVE SUNDAY AFTERNOON AND WILL PRIMARILY IMPACT THE NORTHERN SLOPES AND MAUKA AREAS. ELSEWHERE...THE SEA BREEZES WILL BRING CLOUDS AND SHOWERS TO THE ISLAND INTERIORS AND LEEWARD SECTIONS SUNDAY AFTERNOON AND EVENING. THE INSTABILITY ALOFT FROM THE UPPER LOW WILL CAUSE LOCALLY HEAVY RAIN ON ALL ISLANDS EXCEPT KAUAI. THE BIG ISLAND SHOULD AGAIN BE THE FOCUS FOR THE HIGHEST CHANCES OF HEAVY RAIN IN THE STATE. WILL BE ADDING A SLIGHT CHANCE FOR THUNDERSTORMS FOR THE BIG ISLAND SHORTLY. THE FRONT WILL WASH OUT NEAR OAHU SUNDAY NIGHT...AND WILL LIKELY BRING LITTLE DIRECT RAINFALL AFTER THIS. LAND BREEZES WILL SET IN SUNDAY NIGHT PUSHING MOST OF THE CLOUDS AND RAIN OFFSHORE. 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 MIDWEEK. LIGHT WINDS ASSOCIATED WITH THE SURFACE TROUGH AND INSTABILITY FROM THE LOW ALOFT WILL CONTINUE THIS DIURNAL CONVECTIVE PATTERN OVER ALL THE ISLANDS THROUGH WEDNESDAY OR THURSDAY. LONG RANGE 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 FOCUS LIGHTER SHOWERS TO WINDWARD AND MAUKA AREAS. ANOTHER TROUGH ALOFT MAY DIG DOWN OVER THE AREA NEXT WEEKEND AND MAY ENHANCE THE WINDWARD SHOWERS. && .AVIATION... CLOUDS AND SHRA OVER WINDWARD AREAS WILL BRING ISOL MVFR OVERNIGHT...BUT LINGERING +SHRA OVER LEEWARD BIG ISLAND WILL PRODUCE TEMPO MVFR/ISOL IFR THRU THE EVENING BEFORE DIMINISHING BY EARLY MORNING. LIGHT WINDS WILL ALLOW WIDESPREAD SEA BREEZES TO DEVELOP IN THE AFTERNOON SUNDAY...WITH CLOUDS AND +SHRA FAVORING INTERIOR AND LEEWARD SECTIONS. && .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 LIKELY LONGER. A MARINE WEATHER STATEMENT ALSO CONTINUES FOR WAVES BREAKING NEAR CHANNEL ENTRANCES AND POSSIBLE HARBOR SURGES. SEE THE SURF ZONE FORECAST AND COLLABORATIVE NEAR SHORE SWELL AND WIND FORECAST FOR OAHU. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY UNTIL 6 PM HST SUNDAY FOR SOUTH SHORES OF ALL ISLANDS. && $$ DISCUSSION/MARINE...FOSTER AVIATION...BIRCHARD Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |