| Current Conditions | ||
| Temp |  | 7.5 C |
| RH | | 16 % |
| Wind | | ESE 12 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 019 FXHW60 PHFO 311330 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 AM HST THU JUL 31 2014 .SYNOPSIS... HIGH PRESSURE FAR NORTH OF THE STATE WILL KEEP TRADE WINDS BLOWING THROUGH THE WEEKEND AND INTO NEXT WEEK. MOST SHOWERS WILL BE LIGHT...AND LIMITED MAINLY TO WINDWARD SLOPES. HOWEVER...A VERY MOIST AIR MASS WILL BRING MORE WIDESPREAD RAIN TO THE BIG ISLAND AND MAUI COUNTY FROM LATER TODAY INTO SATURDAY...AND POSSIBLY INCREASED SHOWERS TO OAHU OR KAUAI AROUND FRIDAY NIGHT. && .DISCUSSION... SURFACE OBSERVATIONS AROUND THE MAIN HAWAIIAN ISLANDS STILL REPORTED LIGHT TO MODERATE TRADE WINDS...AND SPEEDS REMAINED HIGHER WHERE THE FLOW ACCELERATED AROUND HEADLANDS AND BETWEEN ISLANDS. PRECIPITATION WAS QUITE SPARSE OVERNIGHT...BUT THE AIR MASS MOISTENED SLIGHTLY... AND THE INVERSION ABOVE IT ROSE CONSIDERABLY OVER THE SOUTHEAST END OF THE STATE. SHREDS OF CIRRUS FOLLOWED A JET STREAM OUT OF THE ITCZ...PASSING OVER THE STATE AT TIMES. BROAD BUT SHALLOW TROUGHING PREVAILED ALOFT TO THE NORTH OF THE STATE...WHILE A MID-LEVEL RIDGE GREW TOWARD THE ISLANDS SLOWLY FROM THE EAST. GUIDANCE MORE SOLIDLY AGREED IN PREDICTING THE ACTIVE ITCZ TO SPOUT A DEEP PLUME OF ENHANCED MOISTURE OVER SEVERAL ISLANDS FROM LATE TODAY INTO SATURDAY. THE MASS OF STRATUS LAYERS VISIBLE ON SATELLITE IMAGES TO THE SOUTHEAST OF THE BIG ISLAND POSSIBLY REPRESENTED THE LEADING EDGE OF THIS PLUME. AS THIS FEATURE MOVES NORTHWEST...SHOWER ACTIVITY WILL INCREASE OVER THE BIG ISLAND...AND THEN MAUI COUNTY. WHILE IT MAY NOT REACH OAHU OR KAUAI AT ALL...MORE LIKELY THESE ISLANDS WILL RECEIVE SOME OF THE CLOUDS AND SHOWERS BY SATURDAY... THOUGH TO A MUCH LESSER DEGREE THAN MAUI OR HAWAII COUNTIES. GUIDANCE ALSO PREDICTED THE MID-LEVEL RIDGE TO EXPAND OVER THE STATE FROM THE EAST DURING THIS TIME...SO SUBSIDENCE WILL LIMIT CLOUD DEVELOPMENT TO SOME DEGREE...THOUGH PROBABLY NOT ENOUGH TO COUNTERACT COMPLETELY THE INFLUENCE OF PLENTIFUL WATER VAPOR. THE SUBTROPICAL RIDGE SHOULD KEEP THE TRADE WINDS BLOWING THROUGH THE FORECAST PERIOD...AND MAY SUPPORT SLIGHTLY INCREASED SPEEDS FROM FRIDAY INTO SATURDAY AS WELL. BY LATE IN THE WEEKEND...SOLUTIONS STARTED TO TREND TOWARD CLIMATOLOGY AGAIN. WIND SPEEDS SHOULD DIMINISH SLIGHTLY...WHILE THE MOIST AIR MASS DEPARTS TOWARD THE WEST...AND DRIER AIR ADVECTS IN FROM THE NORTHEAST. && .AVIATION... VFR CONDITIONS WILL PREVAIL ACROSS THE STATE THROUGH THIS AFTERNOON. PASSING SHOWERS AND BRIEF MVFR CONDITIONS WILL AFFECT MAINLY WINDWARD SLOPES. INCREASING TROPICAL MOISTURE IS FORECAST TO MOVE INTO THE BIG ISLAND LATER THIS AFTERNOON AND TONIGHT...BRINGING THE POTENTIAL FOR MORE WIDESPREAD SHOWERS AND MVFR CONDITIONS ALONG WITH AREAS OF MOUNTAIN OBSCURATION. AIRMET SIERRA MAY BE NEEDED FOR PARTS OF THE BIG ISLAND AT THAT TIME. TYPICAL TRADE WIND CONDITIONS SHOULD PREVAIL ACROSS THE SMALLER ISLANDS THROUGH TONIGHT...WITH ISOLATED MVFR CONDITIONS REMAINING CONFINED PRIMARILY TO WINDWARD SLOPES. DUE TO CONTINUED MODERATE TO LOCALLY BREEZY TRADE WINDS...AIRMET TANGO FOR LOW LEVEL TURBULENCE REMAINS IN EFFECT...COVERING THE AREAS OVER AND IMMEDIATELY SOUTH THROUGH WEST OF THE HIGHER TERRAIN. && .MARINE... A SMALL CRAFT ADVISORY /SCA/ REMAINED IN EFFECT FOR TYPICALLY WINDY WATERS AROUND MAUI COUNTY AND THE BIG ISLAND THROUGH FRIDAY. THE ADVISORY LIKELY WILL BE EXTENDED SEVERAL TIMES INTO NEXT WEEK. A SMALL TO MODERATELY LARGE SWELL FROM THE SOUTH-SOUTHWEST SHOULD ARRIVE OVER THE WEEKEND. OTHERWISE...A SERIES OF SMALL SOUTH SWELLS WILL KEEP ARRIVING THROUGH NEXT WEEK. PREVAILING TRADE WINDS WILL CONTINUE TO PRODUCE SHORT-PERIOD...CHOPPY SURF ALONG EAST-FACING SHORES. && .HFO WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR MAALAEA BAY- PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS. && $$ DISCUSSION/MARINE...RYSHKO AVIATION...JACOBSON Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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