Red Flag Warning 6, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST SAT MAY 22 2010

.SYNOPSIS...
HIGH PRESSURE NORTHEAST OF THE STATE WILL PRODUCE MODERATE TO BRISK
TRADE WINDS INTO THE FIRST HALF OF NEXT WEEK. THE TRADES WILL USHER
IN SHOWER-BEARING CLOUDS TO WINDWARD AND MAUKA SECTIONS. AN UPPER
LEVEL LOW MOVING OVER THE ISLANDS SUNDAY AND MONDAY WILL BRING
ADDITIONAL SHOWERS TO THE ISLANDS.
&&

.DISCUSSION...
THERE ARE NO CHANGES TO THE FORECAST LOGIC THIS MORNING...SO WILL
STICK WITH THE PREVIOUS DISCUSSION. THERE IS A GREATER CHANCE OF
RAPID FIRE GROWTH THIS AFTERNOON...SO PLEASE READ THE FIRE WEATHER
SECTION BELOW.

.PREVIOUS DISCUSSION...
MODEL AGREEMENT REMAINS GOOD WITH THE HIGH PRESSURE SYSTEM NORTHEAST
OF THE ISLANDS BEING THE DOMINATE WEATHER FEATURE FOR MOST OF THE
WEEK. THERE IS ALSO GOOD AGREEMENT WITH AN UPPER LEVEL LOW MOVING
OVER THE ISLANDS...MAINLY OVER THE BIG ISLAND...SUNDAY THROUGH
MONDAY NIGHT.

THE HIGH PRESSURE SYSTEM AT THE SURFACE WILL CONTINUE TO BRING
TRADES TO THE ISLAND FOR THE FORECAST PERIOD...AND WILL KEEP MOST OF
THE SHOWER ACTIVITY TO THE WINDWARD AND MAUKA AREAS. THE AIRMASS
OVER AND UPSTREAM OF THE ISLANDS REMAINS ON THE DRY SIDE...SO
RAINFALL VALUES WILL CONTINUE TO BE ON THE LIGHT SIDE.

THAT BEING SAID...THE UPPER LEVEL LOW WILL LIKELY HELP TO RAISE THE
INVERSION LEVELS AROUND THE ISLANDS...WHICH COULD RESULT IN AN
INCREASE IN SHOWERS. STILL NOT SEEING ENOUGH INSTABILITY OR MOISTURE
FOR THE UPPER LEVEL LOW TO TRIGGER HEAVY SHOWERS...SO THAT REMAINS
OUT OF THE GRIDS.

LATER ON IN THE WEEK HOWEVER...THE GFS IS SHOWING COLDER
TEMPERATURES AT 500 MB. THIS COULD MEAN THAT HEAVIER SHOWERS ARE
POSSIBLE TOWARDS MID WEEK...BUT WITH THE MODELS NOT SO GOOD ON THE
TIMING HERE...WILL HOLD OFF ON MAKING ANY CHANGES THAT FAR OUT.

WINDS ATOP HALEAKALA CAME BACK UP OVERNIGHT...AND IT LOOKS LIKE THEY
WILL REMAIN ABOVE THE ADVISORY LEVEL OF 30 MPH THROUGH TOMORROW
AFTERNOON.

&&

.MARINE...
THE WINDY CONDITIONS HAVE TRIGGERED A SMALL CRAFT ADVISORIES FOR
THE CHANNELS...MAALAEA BAY AND WATERS SOUTH OF THE BIG ISLAND.

&&

.AVIATION...
VFR CEILINGS AND VISIBILITIES WILL PREVAIL WITH MVFR CEILINGS AND
VISIBILITIES POSSIBLE WITH TRADE SHOWERS. AIRMET TANGO IS IN EFFECT
FOR TURBULENCE BELOW 7000 FEET.

&&

.FIRE WEATHER...
RELATIVE HUMIDITIES ARE RUNNING BELOW THOSE CALCULATED YESTERDAY...
SO THEY MAY VERY WELL DROP BELOW THE 45 PERCENT THRESHOLD. COMBINED
WITH THE VERY HIGH KBDI AND THE BRISK TRADES...THERE IS A GREATER
CHANCE OF RED FLAG CONDITIONS OVER LEEWARD SECTIONS THIS AFTERNOON.
WILL BE KEEPING A CLOSE EYE ON THE SITUATION.

&&

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

WIND ADVISORY FOR HALEAKALA SUMMIT UNTIL 6 PM HST SUNDAY.

&&

CRAIG