Current Conditions
Temp4.2 C
RH31 %
WindESE 35 mph
RoadOpen (4x4 only)
Menu of Text Products for the Hawaiian Islands and the Tropical Pacific/Atlantic Oceans:
Narrow the Menu List
Select Time Limit: 12 hours | 24 hours | 48 hours | 72 hours | No time limit
Select Product Type: All | Routine Bulletins/FCSTS | Warnings/Watches/Advisories | HAWN Weather | Tropical | Marine | Aviation | Daily Obs | Special
Hawaiian Islands Synoptic Discussion and Guidance

488
FXHW60 PHFO 300130
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST WED JUL 29 2015

.SYNOPSIS...
A HIGH TO THE NORTHEAST AND A SERIES OF WEAK TROPICAL DISTURBANCES
TO THE SOUTH WILL MAINTAIN LOCALLY BREEZY TRADE WINDS THROUGH EARLY
NEXT WEEK. THE TRADES WILL BRING SOME SHOWERS TO WINDWARD AREAS...
MOSTLY DURING NIGHTS AND MORNINGS. LEEWARD AREAS WILL REMAIN MOSTLY
DRY EXCEPT FOR AFTERNOON SHOWERS OVER THE KONA SLOPES. A TROPICAL
DISTURBANCE MAY PASS NORTHEAST OF THE AREA BY THE MIDDLE OF NEXT
WEEK...BRINGING MUGGY WEATHER.

&&

.DISCUSSION...
SATELLITE AND RADAR LOOPS SHOW VERY DRY WEATHER OVER THE MAIN
HAWAIIAN ISLANDS. SURFACE OBSERVATIONS SHOW MOSTLY SUNNY SKIES
AND LOCALLY BREEZY TRADE WINDS. AS THE SUN SETS THIS EVENING THE
CLOUDS OVER THE KONA SLOPES OF THE BIG ISLAND WILL DISSIPATE AND
CLOUDS AND SHOWERS WILL INCREASE OVER WINDWARD AREAS.

THE GLOBAL MODELS REMAIN IN GOOD AGREEMENT OVER THE NEXT WEEK. A
1027 MB SURFACE HIGH 1850 MILES NORTH NORTHEAST OF OAHU NEAR 43N137W
IS FORECAST TO MOVE SOUTHWEST TO A POSITION AROUND 1300 MILES NORTH
OF OAHU BY FRIDAY NIGHT...THEN REMAIN NEARLY STATIONARY. THE 29/18Z
GFS SHOWS THE HIGH WITH A CENTRAL PRESSURE ONLY UP TO 1027 MB
THROUGH THE WEEKEND. THAT WOULD NOT NORMALLY BE A STRONG ENOUGH HIGH
TO SUPPORT VERY STRONG TRADES OVER THE ISLANDS. HOWEVER...A TROPICAL
DISTURBANCE ABOUT 900 MILES SOUTHEAST OF HILO IS FORECAST TO PASS
SOUTH OF THE ISLANDS TOMORROW NIGHT AND T.D. 8E...NOW ABOUT 1200
MILES EAST SOUTHEAST OF HILO IS...FORECAST TO WEAKEN TO A
DISTURBANCE AND PASS SOUTH OF THE ISLANDS...SUNDAY AND MONDAY. THE
PRESSURE GRADIENT BETWEEN THE HIGH TO THE NORTHEAST AND THE
DISTURBANCES TO THE SOUTH WILL REMAIN RATHER TIGHT THROUGH AT LEAST
SATURDAY EVENING. THAT WILL KEEP BREEZY TRADE WINDS BLOWING OVER THE
ISLANDS.

CLOUD COVER HAS BEEN VERY SPARSE IMMEDIATELY UPSTREAM OF THE
ISLANDS TODAY BUT SATELLITE LOOPS SHOW A BAND OF BROKEN LOW CLOUDS
JUST EAST OF THE BIG ISLAND. THAT BAND MARKS THE EDGE OF AN AREA OF
GREATER LOW-CLOUD COVER EXTENDING FAR UPSTREAM TO THE EAST OF THE
ISLANDS. THE TRADE WINDS WILL CARRY THESE CLOUDS OVER THE ISLANDS
STARTING TONIGHT AND RAINFALL OVER WINDWARD AREAS WILL INCREASE TO
NORMAL SUMMERTIME LEVELS...OR POSSIBLY A BIT WETTER.

THE FORECAST REMAINS RATHER UNCERTAIN AFTER THE COMING WEEKEND. A
TROPICAL DISTURBANCE ABOUT 2150 MILES EAST SOUTHEAST OF HILO IS
EXPECTED TO DEVELOP INTO A TROPICAL CYCLONE AND MOVE WEST OF 140W
INTO THE CENTRAL PACIFIC OVER THE WEEKEND. THE WEATHER OVER THE MAIN
HAWAIIAN ISLANDS NEXT WEEK WILL DEPEND ON THE PROGRESS OF THIS
TROPICAL SYSTEM. THE GLOBAL MODELS CURRENTLY SHOW THE SYSTEM PASSING
NORTHEAST OF THE MAIN HAWAIIAN ISLANDS THROUGH THE MIDDLE OF NEXT
WEEK. THAT WOULD LIKELY BRING LIGHT WINDS AND MUGGY WEATHER TO THE
ISLANDS. HOWEVER...IT IS TOO SOON TO KNOW EXACTLY WHAT THE
DISTURBANCE WILL DO. THE NATIONAL HURRICANE CENTER IN MIAMI WILL BE
ISSUING FORECASTS ON THE SYSTEM FOR THE NEXT FEW DAYS. IF THE SYSTEM
DOES MOVE INTO THE CENTRAL PACIFIC...THE CENTRAL PACIFIC HURRICANE
CENTER IN HONOLULU WILL TAKE OVER THE FORECASTS.

&&

.AVIATION...
NO AIRMETS ARE CURRENTLY IN EFFECT AND VFR COND PREVAIL. INCREASING
CLOUDS AND SHOWERS COULD BRING MVFR COND TO SOME WINDWARD AREAS
TONIGHT AND REQUIRE AIRMET SIERRA FOR MTN OBSC. ALSO...TRADE WINDS
MAY STRENGTHEN ENOUGH TO REQUIRE AIRMET TANGO FOR LOW LEVEL TURB.

&&

.FIRE WEATHER...
WITH THE TRADE WINDS STRENGTHENING AND RELATIVELY DRY WEATHER...THE
FIRE DANGER HAS INCREASED. WINDS SPEEDS REACHED 18 KT AT HONOLULU
AIRPORT TODAY WITH A DEW POINT OF 68 DEGREES AND THE RELATIVE
HUMIDITY DOWN TO 50 PERCENT. THE TRADE WINDS ARE EXPECTED TO REMAIN
BREEZY...BUT MORE-HUMID AIR MOVING OVER THE AREA TONIGHT SHOULD KEEP
CONDITIONS FROM REACHING RED-FLAG WARNING LEVELS.

&&

.MARINE...
A SMALL CRAFT ADVISORY IS POSTED FOR THE WINDY WATERS AROUND THE BIG
ISLAND AND MAUI THROUGH SATURDAY EVENING. THE ADVISORY MAY NEED TO
BE EXPANDED TO INCLUDE SOME AREAS AROUND OAHU AND KAUAI.

NO MAJOR SWELLS ARE EXPECTED FOR THE NEXT SEVERAL DAYS. SURF IS
EXPECTED TO REMAIN WELL BELOW THE ADVISORY THRESHOLD ALONG ALL
SHORES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 PM HST SATURDAY FOR THE PAILOLO AND
ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF THE BIG
ISLAND.

&&

$$
DONALDSON



Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office