| Current Conditions | ||
| Temp |  | 8.0 C |
| RH | | 20 % |
| Wind | | E 15 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 850 FXHW60 PHFO 241930 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1000 AM HST THU APR 24 2014 .SYNOPSIS... BREEZY TRADE WINDS WILL GRADUALLY INCREASE INTO FRIDAY...WEAKEN SUNDAY AND MONDAY...THEN RECOVER BY THE MIDDLE OF NEXT WEEK AS HIGH PRESSURE TO OUR NORTH FLUCTUATES IN STRENGTH. CLOUDS AND SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS THROUGH THE FORECAST PERIOD. && .DISCUSSION... A 1029 MB HIGH CENTERED NEAR 35N155W...ABOUT 920 MILES NORTH OF THE MAIN HAWAIIAN ISLANDS...HAS RIDGES EXTENDING SOUTHEAST THROUGH 30N130W AND SOUTHWEST THROUGH 28N180W...SPANNING THE CENTRAL NORTH PACIFIC. THE PRESSURE GRADIENT BETWEEN THE HIGH WITH ITS RIDGES TO OUR NORTH AND EQUATORIAL LOW PRESSURE IS SUFFICIENTLY STEEP TO SUPPORT MODERATE TO LOCALLY STRONG TRADE WINDS ACROSS LOCAL WATERS THIS MORNING. BECAUSE OF THIS...AND BECAUSE OF ANTICIPATED STRONGER WINDS FRIDAY...A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL LOCAL WATERS THROUGH FRIDAY AFTERNOON. WEAK TROUGHING ALOFT SHOWS UP IN MORNING SOUNDINGS INDICATING CAPE BETWEEN 600 AND 1200 J/KG AND NEGATIVE LIFTED INDEX VALUES. HOWEVER...A TRADE INVERSION NEAR 8100 FEET SHOWS RIDGING AND A BIT OF SUBSIDENCE IS OCCURRING AT LOWER LEVELS. SATELLITE LOOP SHOWS PATCHY BROKEN LOW CLOUDS EMBEDDED IN THE TRADES UPWIND FROM THE ISLANDS...WITH A TYPICAL PATCHWORK OF BROKEN TO OVERCAST SHOWERY LOW CLOUDS ACROSS WINDWARD AND MAUKA SECTIONS OF THE SMALLER ISLANDS. RADAR DATA SHOWS SCATTERED TO NUMEROUS SHOWERS ACROSS THESE SAME AREAS THIS MORNING. MODELS SHOW THE CURRENT TRADE WIND PATTERN WILL CONTINUE INTO THE WEEKEND. HOWEVER...UPPER TROUGHING EXPECTED TO MOVE IN FROM THE NORTHWEST MAY WEAKEN THE RIDGE TO OUR NORTH SUNDAY AND MONDAY...CAUSING TRADE WINDS TO DECREASE ON THOSE DAYS. A STRONGER REINFORCING HIGH WILL MOVE IN FROM THE NORTHWEST EARLY NEXT WEEK...STEEPENING THE PRESSURE GRADIENT AND BOOSTING TRADE WINDS AGAIN BY THE MIDDLE OF NEXT WEEK. && .AVIATION... SHRA/-RA WILL PRODUCE ISOL MVFR CONDITIONS ALONG WINDWARD SECTIONS. WINDWARD FIELDS MAY SEE INTERMITTENT MVFR OBS HOWEVER MAINLY SHORT LIVED. ELSEWHERE VFR WILL PREVAIL. STRONG TRADES NE G30KT WILL CONTINUE TO PRODUCE LLVL LEE TURB THROUGH THE PERIOD. AIRMET TANGO WILL REMAIN POSTED. HIGH LEVEL JET RELATED CHOP MAY INCREASE OVER THE WRN PORTION OF THE STATE AFT 25/06Z. && .MARINE... A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL WATERS IN ANTICIPATION OF STRENGTHENING WINDS AND BUILDING COMBINED SEAS THROUGH FRIDAY AFTERNOON...BUT MAY BE REDUCED IN AREA TO THE TYPICALLY WINDY WATERS AROUND THE BIG ISLAND AND MAUI ON SATURDAY NIGHT OR SUNDAY. NORTHEASTERLY WINDS WILL REACH THEIR MINIMUM SPEEDS LATE SUNDAY OR MONDAY...AND THEN INCREASE AGAIN BY THE MIDDLE OF NEXT WEEK. PERSISTENT TRADE WINDS WILL BUILD SEAS...PRODUCING ROUGH SURF NEAR THE ADVISORY LEVEL ALONG EAST-FACING SHORES BY FRIDAY. INCREASING SEAS ALSO CONTRIBUTE TO THE NEED FOR THE SMALL CRAFT ADVISORY. SEAS WILL DIMINISH WITH THE WINDS LATE SATURDAY AND SUNDAY. A NORTHWEST SWELL WILL PRODUCE BELOW-ADVISORY SURF ALONG EXPOSED SHORES OF THE SMALLER ISLANDS TODAY. THE SWELL WILL DROP FRIDAY AND SATURDAY...BUT A SMALL REINFORCING NORTHWEST SWELL MAY ARRIVE LATE SUNDAY INTO TUESDAY. && .HFO WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR ALL HAWAIIAN WATERS- && $$ PUBLIC/MARINE...POWELL AVIATION...DEJESUS Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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