| Current Conditions | ||
| Temp |  | 1.5 C |
| RH | | 76 % |
| Wind | | WNW 10 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 018 FXHW60 PHFO 111959 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 959 AM HST TUE MAR 11 2014 .SYNOPSIS... GENTLE TRADE WINDS ACROSS HAWAII TODAY WILL KEEP SHOWERS AND CLOUDS MAINLY ACROSS WINDWARD AND MAUKA AREAS...ALTHOUGH A FEW INTERIOR AND LEEWARD BUILDUPS MAY OCCUR ONCE AGAIN THIS AFTERNOON. TRADES WILL THEN INCREASE SOMEWHAT WEDNESDAY THROUGH THURSDAY... WITH CLOUDS AND SHOWERS FAVORING WINDWARD AND MAUKA AREAS. A COLD FRONT WILL MOVE THROUGH THE STATE FRIDAY NIGHT. STRONG AND GUSTY TRADE WINDS ARE EXPECTED BEHIND THE FRONT THROUGH THE WEEKEND. && .DISCUSSION... TRANQUIL WEATHER CONDITIONS PREVAIL ACROSS THE STATE THIS MORNING... WITH AREA RADARS AND RAIN GAUGES SHOWING MINIMAL SHOWER ACTIVITY DURING THE PAST SEVERAL HOURS. MORNING VISIBLE SATELLITE IMAGERY INDICATES MOSTLY CLEAR SKIES...EXCEPT ACROSS WINDWARD KAUAI WHERE PARTLY TO MOSTLY CLOUDY CONDITIONS PREVAIL. LOOKING AT THE REGIONAL VIEW...CLUSTERS OF THUNDERSTORMS ARE ACTIVE TO THE EAST NORTHEAST OF HAWAII BETWEEN 145-150W...UNDERNEATH A MID/UPPER LEVEL TROUGH. THIS TROUGH WAS JUST PASSING EAST OF HAWAII WHEN THE 12Z SOUNDINGS WERE LAUNCHED...PRODUCING FAIRLY COOL 500 MB TEMPS OF -11C AT HILO AND -13C AT LIHUE. HOWEVER A DEEP LAYERED ANTICYCLONE CENTERED NEAR 20N 180 IS BUILDING EASTWARD INTO THE STATE...AND WILL PROVIDE STABLE CONDITIONS OVER THE NEXT FEW DAYS. AT THE SURFACE...TRADE FLOW ACROSS THE STATE REMAINS SOMEWHAT WEAKENED THIS MORNING DUE TO THE REMNANTS OF AN OLD FRONTAL BOUNDARY TO OUR NORTH AND NORTHWEST...AND A WEAK TROUGH TO OUR EAST NEAR 150W. FOR THE REST OF TODAY...GENTLE TRADES WITH LIMITED WINDWARD AND MAUKA SHOWER ACTIVITY SHOULD BE THE RULE. HOWEVER...THE TRADES MAY BE JUST WEAK ENOUGH TO ALLOW FOR ONE MORE AFTERNOON OF AT LEAST ISOLATED INTERIOR AND LEEWARD CLOUD BUILDUPS...AND CANNOT TOTALLY RULE OUT A FEW SHOWERS POPPING UP IN THOSE AREAS AS WELL. THE EXISTING FORECAST APPEARS TO HAVE A GOOD HANDLE ON THE EXPECTED CONDITIONS...AND NO UPDATE IS PLANNED. WEDNESDAY THROUGH THURSDAY...MODERATE TRADES WILL PREVAIL ACROSS THE STATE AS A HIGH PRESSURE RIDGE REMAINS NORTH OF THE AREA. A MID LEVEL RIDGE BUILDING IN FROM THE WEST SHOULD PROVIDE STABLE CONDITIONS ALOFT. LIMITED SHOWER ACTIVITY WILL CONTINUE TO FAVOR WINDWARD AND MAUKA SECTIONS. THE NEXT COLD FRONT WILL APPROACH THE STATE FROM THE NORTHWEST THURSDAY NIGHT...LIKELY REACHING KAUAI ON FRIDAY AND SWEEPING THROUGH THE REST OF THE STATE FRIDAY NIGHT. MODEL DATA SUGGESTS THAT THIS FRONT WILL HAVE ONLY SHALLOW MOISTURE AND LIMITED SUPPORT ALOFT...THUS WIDESPREAD HEAVY RAINS OR THUNDERSTORMS ARE NOT CURRENTLY EXPECTED. THE MAIN WEATHER IMPACT WILL BE STRONG TRADE WINDS EXPECTED BEHIND THE FRONT FOR THE WEEKEND. THESE STRONG TRADES ALONG WITH SUFFICIENT LOW LEVEL MOISTURE STILL IN PLACE SHOULD GENERATE CONSIDERABLE SHOWER ACTIVITY ACROSS THE FAVORED WINDWARD SECTIONS. TRADES SHOULD DIMINISH SLIGHTLY EARLY NEXT WEEK...BUT AT LEAST MODERATE TRADES APPEAR LIKELY TO CONTINUE AS A BLOCKED PATTERN DEVELOPS OVER THE EASTERN PACIFIC AND A STRONG SURFACE HIGH REMAINS ANCHORED NNE OF HAWAII. THE PREVIOUS 00Z ECMWF RUN HAD DROPPED A MID LEVEL LOW JUST NE OF THE STATE EARLY NEXT WEEK... BUT THE NEW 12Z RUN HAS COME INTO LINE WITH OTHER GUIDANCE... JUST SHOWING A WEAK MID LEVEL TROUGH EAST/SOUTHEAST OF HAWAII WITH A DEEP RIDGE OVER AND WEST OF THE STATE. THUS WOULD EXPECT TYPICAL TRADE CONDITIONS TO PERSIST INTO NEXT WEEK. && .AVIATION... VFR WILL BE THE RULE FOR THE TERMINALS TODAY THRU 12/08Z. FROM 12/08Z-12/16Z WINDWARD FIELDS AND SECTIONS MAY SEE SHORT LIVED MVFR CIGS. THE BIG ISLAND HAS CLEARED AND AIRMET SIERRA WAS CANCELED AS OF 11/1745Z. LGT-MOD NE TRADES SHOULD HOLD TODAY AND REMAIN STRONG ENOUGH TO SUPPRESS ANY SEA BREEZE DEVELOPMENT AS WELL AS RESULTANT AFTERNOON TCU/+RA OVR LEEWARD/INTERIOR SECTIONS. ISOL +TSRA IS IN PROGRESS IMMEDIATELY ENE OF HAWAII AND MAY AFFECT MAINLAND TRAFFIC NEAR VCY N23W148. THE TS ARE PRODUCING FREQUENT LTG HOWEVER REMAIN ISOLD. THERE IS NO SIGMET AT THE MOMENT HOWEVER ONE COULD BE ISSUED IF THE TS AREA FILLS IN MORE. ALSO A SHARPENING TROUGH ALF OVER THE SAME AREA WILL BEGIN PRODUCE MORE TURB AOA FL270 ALG 150W AFT 12/00Z. TURB WILL INCREASE AFT 12/06Z AND SPREAD NEWD. && .MARINE... FORERUNNERS OF A MODERATE NW SWELL HAVE ARRIVED AT BUOY 51101 DURING THE PAST FEW HOURS. THIS SWELL IS EXPECTED TO BUILD INTO THE ISLANDS TONIGHT...THEN PEAK ON WEDNESDAY A BIT BELOW ADVISORY LEVELS. THIS SWELL WILL THEN SUBSIDE WEDNESDAY NIGHT THROUGH FRIDAY MORNING. A NEW SLIGHTLY LARGER NW SWELL IS FORECAST TO ARRIVE FRIDAY...PEAKING FRIDAY NIGHT INTO SATURDAY AT ADVISORY LEVELS. TRADE WINDS WILL APPROACH SMALL CRAFT ADVISORY /SCA/ LEVELS WEDNESDAY THROUGH THURSDAY IN THE TYPICALLY WINDIER WATERS AROUND MAUI COUNTY. TRADES WILL INCREASE FURTHER FRIDAY NIGHT THROUGH THE WEEKEND...WITH SCA BECOMING LIKELY FOR ALL HAWAIIAN WATERS AND A CHANCE FOR GALES IN ALENUIHAHA CHANNEL. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ PUBLIC/MARINE...JACOBSON AVIATION...DEJESUS Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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