Heavy Rain in Hawaii, February 18 to 19, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE FEB 18 2014

.SYNOPSIS...
AN UPPER LEVEL TROUGH JUST WEST OF KAUAI WILL BRING UNSETTLED
WEATHER TO THE GARDEN ISLAND THIS MORNING. THIS TROUGH WILL WEAKEN
AND PASS OVER THE STATE LATER TODAY. A SURFACE LOW PRESSURE
SYSTEM NORTHWEST OF THE ISLANDS WILL WEAKEN TO A TROUGH...WITH WINDS
TURNING MORE SOUTHEAST AND PERSISTING OVER THE ISLANDS THROUGH THE
REST OF THE WORK WEEK.

&&

.DISCUSSION...
RATHER ACTIVE WEATHER HAS DEVELOPED IN KAUAI VICINITY EARLY THIS
MORNING...AS AN UPPER LEVEL TROUGH FROM THE WEST ADVANCES CLOSER TO
THE ISLAND. MUCH OF THE SHOWERS AND EVEN THUNDERSTORMS ASSOCIATED
WITH THE SYSTEM ARE NORTH OF THE ISLAND AT THIS TIME...THOUGH RADAR
DATA INDICATE THERE ARE FEW HEAVY SHOWERS IN THE ISLAND VICINITY.
FORTUNATELY...THESE SHOWERS ARE MOVING QUITE RAPIDLY NORTHWARD...AND
THIS QUICK MOTION WILL MINIMIZE THE RAINFALL ACCUMULATION FOR ANY
ONE LOCATION. THEREFORE HAVE CANCELED THE FLOOD WATCH FOR KAUAI
COUNTY...BUT STILL HAVE HEAVY RAINFALL POSSIBLE AS WELL AS A SLIGHT
CHANCE OF THUNDERSTORMS FOR KAUAI THIS MORNING. AS THIS UPPER LEVEL
TROUGH MOVES EAST OF KAUAI LATER TODAY....WEATHER SHOULD IMPROVE FOR
THE ISLAND BY THE AFTERNOON.

THE HIGHER LEVEL MOISTURE FLOW FROM THE SOUTH IS ALSO DECREASING
ACROSS THE STATE EARLY THIS MORNING...WITH MUCH HIGH CLOUDS CLEARING
THE WESTERN ISLANDS AT THIS TIME. EVEN THOUGH THERE MAY STILL BE
PASSING SHOWERS AFFECTING THE SUMMITS OF THE BIG ISLAND
TODAY...BELIEVE THE THREAT OF SIGNIFICANT WINTER WEATHER FOR THE
SUMMITS IS DIMINISHED AND SO THE WINTER WEATHER ADVISORY FOR THAT
AREA HAS BEEN CANCELLED.

AS THE UPPER LEVEL TROUGH PASSES OVER THE ISLANDS LATER TODAY...THE
AIR MASS WILL REMAIN UNSTABLE OVER THE REST OF THE ISLANDS. WITH THE
HIGH CLOUDS CLEARING ACROSS THE STATE...EXPECT MORE LOW CLOUDS AND
EVEN SHOWERS TO DEVELOP OVER THE REST OF STATE UNDER IMPROVED
DAYTIME HEATING. FORECAST CHARTS STILL SHOW A WEAK MID LEVEL HIGH
PASSING OVER THE STATE IN THE NEXT FEW DAYS...BEGINNING WEDNESDAY.
IN TURN...THE ATMOSPHERIC CONDITIONS WILL BECOME A LITTLE MORE
STABLE OVER THE ISLANDS DURING THE PASSAGE OF THIS FEATURE. A
SURFACE LOW CURRENTLY NORTHWEST OF KAUAI WILL SLOWLY WEAKEN...AND
BECOME A NEARLY STATIONARY TROUGH LOCATING JUST WEST OF THE STATE.
THIS WILL RESULT IN WINDS TURNING MORE SOUTHEAST OVER THE ISLANDS
IN THE NEXT FEW DAYS. LOW CLOUDS AND SHOWERS EMBEDDED IN THE
SOUTHEASTERLY WINDS WILL AFFECT MAINLY THE EASTERN PORTIONS OF THE
ISLANDS.

LATEST FORECAST CHARTS STILL INDICATE THIS SURFACE TROUGH WILL
EVENTUALLY MOVE ACROSS THE STATE BY THE NEXT WEEKEND. THIS MAY ONCE
AGAIN BRING MORE UNSETTLED WEATHER TO THE ISLANDS. ON THE OTHER
HAND...THIS TROUGH PASSAGE IS FORECAST TO BE SWIFT...WITH
NORTHEASTERLY WINDS TO RETURN TO THE ISLANDS BEHIND THE TROUGH.
MODEL SOLUTIONS ALSO CONTINUE TO SHOW DRIER WEATHER CONDITIONS
RETURNING TO THE STATE AS WELL.

&&

.AVIATION...
AIRMET SIERRA IS POSTED FOR MOUNTAIN OBSCURATION ACROSS THE SMALLER
ISLANDS FROM MAUI THROUGH KAUAI...WHILE AIRMET ZULU IS POSTED FOR
LIGHT TO MODERATE ICING WITHIN THICK CLOUDINESS BETWEEN 14000 FEET
AND 30000 FEET FROM THE BIG ISLAND THROUGH OAHU. AREAS OF MVFR CIGS
WITH MOUNTAIN OBSCURATION WILL PERSIST ACROSS THE SMALLER ISLANDS
INTO THE MORNING HOURS...WITH GRADUAL IMPROVEMENT EXPECTED THIS
AFTERNOON. ICING SHOULD END FROM WEST TO EAST ACROSS THE STATE
DURING THE MORNING AND EARLY AFTERNOON...AS THE SHIELD OF THICK
MID/HIGH CLOUDINESS SHIFTS EASTWARD.

OTHERWISE...SCATTERED TO NUMEROUS SHOWERS WITH ASSOCIATED BRIEF
MVFR/IFR CONDITIONS WILL AFFECT THE STATE TODAY. A FEW THUNDERSTORMS
WILL BE POSSIBLE OVER AND AROUND KAUAI AS WELL.

&&

.MARINE...
COASTAL WINDS WILL REMAIN BELOW SMALL CRAFT CONDITIONS THROUGH THE
REST OF THE WEEK. WHILE THERE WILL BE INCOMING NORTHERLY AND
WESTERLY SWELLS THROUGH REST OF THE WEEK...THE COMBINED SEA
HEIGHTS WILL REMAIN BELOW SMALL CRAFT LEVEL.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

AVIATION...JACOBSON
REST...HUI