Area Forecast Discussion
Issued by NWS Honolulu, HI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXHW60 PHFO 280628
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST THU AUG 27 2015

.UPDATE...
TONIGHT/S FORECAST IS ON TRACK AS SPOTTY AFTERNOON CONVECTION OVER
THE ISLANDS HAS COLLAPSED. THERE HAS BEEN A RECENT UPTICK IN SHOWER
ACTIVITY SEEN ON RADAR...MAINLY OVER WATERS AROUND OAHU AND THE MAUI
COUNTY. SINCE THE ATMOSPHERE REMAINS MOIST AND SOMEWHAT UNSTABLE...
WE WILL HAVE TO MONITOR THE SHOWERS...BUT WE STILL EXPECT A DECREASE
IN RAINFALL DURING THE OVERNIGHT HOURS. WITH DEW POINT TEMPERATURES
HOVERING IN THE LOW TO MID 70S...HUMID CONDITIONS WILL PERSIST...AND
OVERNIGHT LOW TEMPS SHOULD BE HIGHER THAN NORMAL.

&&

.SYNOPSIS...
HUMID...MOIST...AND SOMEWHAT UNSTABLE CONDITIONS WILL PERSIST AS
WEAK TRADE WINDS GRADUALLY REBUILD ON FRIDAY. ALTHOUGH SHOWERS
WILL FAVOR WINDWARD AND MAUKA AREAS...AFTERNOON CLOUDS AND SPOTTY
SHOWERS CAN BE EXPECTED OVER LEEWARD AREAS WITH FLASH FLOODING
REMAINING A POSSIBILITY OVER THE SMALLER ISLANDS. HURRICANE IGNACIO
WILL APPROACH THE STATE LATE IN THE WEEKEND AND WILL AFFECT ISLAND
WEATHER NEXT WEEK.

&&

.PREV DISCUSSION 400 PM...
THE ATMOSPHERE AROUND THE STATE REMAINS MOIST AND UNSTABLE WITH
DEW POINTS IN THE MID 70/S AND A MID TO UPPER LEVEL TROUGH
LINGERING JUST NORTH OF THE ISLANDS. DAYTIME HEATING AND SEA
BREEZE CONVERGENCE WERE ENOUGH TO PRODUCE HEAVY SHOWERS AND
THUNDERSTORMS OVER OAHU THIS AFTERNOON WITH SPOTTY SHOWERS OVER
THE REST OF THE STATE. SHOWERS WILL TAPER OFF DURING THE EVENING
HOURS. SIMILAR CONDITIONS ARE EXPECTED OVER THE SMALLER ISLANDS
FRIDAY AND WITH THE GROUND ALREADY SATURATED...FLOODING COULD
HAPPEN QUICKLY. THE FLASH FLOOD WATCH HAS BEEN EXTENDED FOR KAUAI
COUNTY...OAHU AND MAUI COUNTY.

DRIER AIR WILL MOVE OVER THE BIG ISLAND FROM THE EAST TONIGHT AND
FRIDAY BRINGING A DROP TO HUMIDITY LEVELS. THE DECREASE IN
HUMIDITY AND WEAK RIDGING OVERHEAD SHOULD BE ENOUGH TO CAP ANY
VIGOROUS CONVECTION FRIDAY AFTERNOON. THEREFOR... THE FLASH FLOOD
WATCH HAS BEEN CANCELLED FOR THE BIG ISLAND.

LIGHT TRADE WINDS ARE EXPECTED FRIDAY WITH MODERATE TRADES FILLING
IN SATURDAY AS HIGH PRESSURE BUILDS SLOWLY NORTH OF THE STATE.
SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS AT NIGHT AND THROUGH
THE MORNING HOURS. HOWEVER...THE TRADES WILL BE WEAK ENOUGH TO
ALLOW AFTERNOON SEA BREEZES TO FORM ALONG LEEWARD COASTS FRIDAY
AFTERNOON. THE SEA BREEZES AND DAYTIME HEATING WILL SHIFT
RAINFALL FOCUS TO CENTRAL AND LEEWARD LOCATIONS WITH HEAVY SHOWERS
AND ISOLATED THUNDERSTORMS POSSIBLE. SATURDAY AND SUNDAY...TRADE
WINDS ARE EXPECTED TO BE SUFFICIENTLY STRONG ENOUGH TO PROHIBIT
WIDESPREAD AFTERNOON SEA BREEZES AND THE ASSOCIATED CONVECTIVE
ACTIVITY.

FORECAST UNCERTAINTY INCREASES SIGNIFICANTLY ON MONDAY AND
TUESDAY...HINGING ON THE EVENTUAL TRACK OF HURRICANE IGNACIO.
HURRICANE IGNACIO WILL APPROACH THE BIG ISLAND LATE IN THE
WEEKEND AND MAY THREATEN THE ISLANDS EARLY NEXT WEEK. FORECAST
TRACK ERRORS AT THAT TIME ARE MORE THAN A COUPLE HUNDRED
MILES...SO IT IS TOO EARLY TO TELL WHAT THE DIRECT IMPACTS WILL
BE. EVERYONE IN THE STATE SHOULD MONITOR THE PROGRESS OF IGNACIO
DURING THE NEXT SEVERAL DAYS...AND THE NATIONAL WEATHER SERVICE
URGES INDIVIDUALS TO HAVE AN ACTION PLAN IN CASE IGNACIO...OR ANY
HURRICANE...THREATENS.

&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL OVERNIGHT...ALTHOUGH A FEW
LINGERING CLOUDS AND SHOWERS OVER THE BIG ISLAND MAY HAVE POCKETS OF
MVFR DURING THE NEXT COUPLE OF HOURS. LIGHT WINDS COMBINED WITH A
MOIST AIRMASS OVER THE SMALLER ISLANDS COULD BRING ANOTHER ROUND OF
SHOWERS WITH MVFR AND ISOLATED IFR CONDITIONS FRIDAY AFTERNOON WITH
CLEARING AGAIN FRIDAY NIGHT.

&&

.MARINE...
WINDS AND SEAS WILL REMAIN SMALL CRAFT ADVISORY LEVELS FOR THE NEXT
COUPLE OF DAYS...WITH ELEVATED SEAS BECOMING A CONCERN BY SUNDAY FOR
PORTIONS OF THE STATE.

IN THE SHORT TERM...A WEST TO WEST-NORTHWEST SWELL WILL BE THE MAIN
CONCERN. THE BARBERS POINT BUOY HAS NOT SHOWN A SIGNIFICANT CHANGE
IN THE SWELL ENERGY THIS EVENING...BUT BUOY 51001 HAS DETECTED AN
INCREASE IN THE 15 TO 16 SECOND BAND DURING THE PAST COUPLE OF
HOURS. WHILE THE IMPACTS OF THIS SWELL WILL BE MODEST ON MOST
ISLANDS...ADVISORY LEVEL SURF COULD DEVELOP ALONG WEST FACING SHORES
OF THE BIG ISLAND FRIDAY AND SATURDAY.

UNCERTAINTY IS VERY HIGH REGARDING THE POTENTIAL IMPACTS ON THE
STATE FROM HURRICANE IGNACIO EARLY NEXT WEEK...BUT WE ARE CONFIDENT
THAT AN EAST-SOUTHEAST SWELL WILL ARRIVE SATURDAY. THIS SWELL WILL
MAINLY IMPACT THE BIG ISLAND AND MAUI...WHERE ADVISORY LEVEL SURF
IS EXPECTED ALONG EAST FACING SHORES SATURDAY THEN LIKELY RISING TO
WARNING LEVELS SUNDAY. SOME OF THIS SWELL ENERGY WILL EVENTUALLY
IMPACT THE REST OF THE STATE...AND SMALL CRAFT ADVISORY CONDITIONS
ARE LIKELY FOR EXPOSED WATERS ON SUNDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH FRIDAY AFTERNOON FOR NIIHAU-KAUAI-OAHU-
MOLOKAI-LANAI-MAUI.


&&

$$
UPDATE/MARINE...WROE
PREV DISCUSSION...MORRISON
AVIATION...MBALLARD






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.