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Hawaiian Islands Synoptic Discussion and Guidance

480
FXHW60 PHFO 251330
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 AM HST SAT OCT 25 2014

.SYNOPSIS...
LIGHT TO MODERATE TRADES CONTINUE THROUGH THE REST OF THE WEEKEND
WITH SHOWERS FAVORING WINDWARD AND MAUKA AREAS. SOME OF THE LARGER
SHOWERS WILL REACH LEEWARD LOCATIONS AT TIMES...INCLUDING THE
HONOLULU METRO AREA. SHOWERS MAY INCREASE TONIGHT AND EARLY SUNDAY
AS A WEAK FRONT REACHES THE ISLANDS FROM THE NORTH. STABLE MODERATE
TRADES ARE EXPECTED THROUGH EARLY NEXT WEEK...THEN STRONGER TRADES
ARE POSSIBLE FOR THE LATER PART OF THE WORK WEEK.

&&

.DISCUSSION...
A STRONG SFC HIGH PRESSURE SYSTEM LOCATED FAR NNE OF THE ALOHA STATE
WILL KEEP A TRADE WIND WEATHER REGIME IN PLACE THROUGH THE REST OF
THE WEEKEND. MOISTURE UPSTREAM OF THE ISLANDS WILL KEEP FEEDING
TRADE WIND SHOWERS...WHICH WILL CONTINUE TO FOCUS OVER WINDWARD AND
MOUNTAIN AREAS. HOWEVER...SOME OF THE LARGER SHOWERS WILL REACH
LEEWARD LOCATIONS AT TIMES...INCLUDING THE HONOLULU METRO AREA.

INFRARED AND WATER VAPOR SATELLITE IMAGERY SHOW A BAND OF CLOUDS AND
SHOWERS ASSOCIATED WITH A WEAKENING FRONTAL BOUNDARY ABOUT 200 MILES
N OF THE ISLANDS...AND MOVING TOWARDS THE AREA. MEANWHILE...A WEAKER
BAND OF SHOWERS IS NOW REACHING WINDWARD AREAS OF THE SMALLER
ISLANDS AND PROVIDING SOME OF THE AFOREMENTIONED ENHANCED MOISTURE
UPSTREAM OF THE ISLANDS. WINDWARD SHOWERS HAVE PERSISTED DURING THE
OVERNIGHT HOURS...WITH THE ENHANCED MOISTURE PROBABLY LINGERING
THROUGH THE AFTERNOON HOURS.

FOR TONIGHT...SHOWERS WILL FURTHER INCREASE AND CONTINUE THROUGH
EARLY SUN AS THE LARGER FRONTAL CLOUD BAND REACHES THE ISLANDS.
LOCALLY HEAVY RAIN IS CERTAINLY POSSIBLE. HOWEVER...MODELS REMAIN
CONSISTENT IN KEEPING HIGH PRESSURE ALOFT OVER THE AREA DURING THE
NEXT SEVERAL DAYS...WHICH SHOULD LIMIT SOMEWHAT RAINFALL COVERAGE.
NEVERTHELESS....EXPECT LIGHT TO MODERATE TRADES WITH PASSING SHOWERS
TO CONTINUE THROUGH EARLY NEXT WEEK WITH BEST CHANCES FOR HEAVIER
RAIN OVER WINDWARD AND MAUKA AREAS.

MODEL SOLUTIONS...ESPECIALLY ECMWF...SHOW THE HIGH PRESSURE FAR NNE
OF THE ISLANDS STRENGTHENING AGAIN DURING THE SECOND HALF OF NEXT
WEEK AS A DEEP TROUGH FAR NW OF THE AREA LIFTS OUT. THIS MAY ALLOW
FOR THE HIGH TO INTENSIFY...BRINGING STRONGER PRESSURE GRADIENTS
ACROSS THE ISLAND CHAIN. THIS SCENARIO REMAINS FAIRLY CONSISTENT
WITH EACH ECMWF MODEL RUN. GFS SOLUTIONS WERE FOLLOWING A MORE
CONSERVATIVE SCENARIO...BUT THE LATEST RUN MAY BE HINTING TOWARDS
THE WINDIER SOLUTION. THUS...POTENTIALLY STRONGER TRADES COULD BE IN
STORE FOR THE LATER PART OF NEXT WEEK.

&&

.AVIATION...
NO AIRMETS ARE IN EFFECT THIS MORNING. PASSING TRADE WIND CLOUDS AND
SHOWERS...IMPACTING WINDWARD AND MAUKA AREAS...WILL PROVIDE ISOLATED
MVFR CEILINGS TODAY. LEEWARD AREAS SHOULD REMAIN VFR.

&&

.MARINE...
SMALL SOUTHERLY AND NORTHWESTERLY SWELLS WILL DECREASE OVER THE NEXT
FEW DAYS. EXPECTING A MODERATE NORTHERLY SWELL FOR THE SECOND HALF
OF NEXT WEEK.

LARGE SCALE TRADE WINDS ARE EXPECTED TO REMAIN IN THE LIGHT TO
MODERATE CATEGORY WHICH MEANS LOCALLY FRESH TRADES IN THE
WINDIER CHANNELS THROUGH THE MIDDLE OF NEXT WEEK. TRADE WINDS ARE
EXPECTED TO INCREASE DRAMATICALLY THURSDAY AND FRIDAY OF NEXT WEEK
AS A STRONG HIGH BUILDS IN TO THE NORTH.

&&

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

&&

$$

DISCUSSION/MARINE...REYNES
AVIATION...FOSTER



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