FXHW60 PHFO 150625
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST MON DEC 14 2009
.SYNOPSIS...
HIGH PRESSURE WILL KEEP THE ISLANDS RELATIVELY DRY THROUGH
WEDNESDAY. A COLD FRONT WILL MOVE DOWN THE ISLAND CHAIN LATE
WEDNESDAY THROUGH EARLY FRIDAY...BRINGING SOME SHOWERS WITH IT. HIGH
PRESSURE BEHIND THE FRONT...WILL BRING BACK MODERATE TRADE WINDS
THIS WEEKEND.
&&
.DISCUSSION...
NO CHANGES IN THE FORECAST PHILOSOPHY AT THIS TIME. DO NOT SEE A
NEED TO UPDATE THE FORECAST AT THIS TIME. PREVIOUS DISCUSSION
FOLLOWS.
&&
.PREV DISCUSSION...
ISSUED AT 400 PM
A FLAT PRESSURE GRADIENT ASSOCIATED WITH A HIGH PRESSURE RIDGE OVER
AND JUST NORTH OF THE ISLANDS WILL KEEP THE WINDS LIGHT AND VARIABLE
WITH LOCAL LAND AND SEA BREEZES INTO WEDNESDAY. STABLE SUBSIDING AIR
WITH THE RIDGE WILL KEEP THE TEMPERATURE INVERSION LOW AND THE STATE
UNDER MOSTLY CLEAR AND DRY SKIES. HOWEVER...A WEAK COLD FRONT JUST
NORTHWEST OF KAUAI IS GETTING TOO CLOSE FOR COMFORT. THEREFORE...THE
KAUAI FORECAST FOR TONIGHT NOW CALLS FOR PARTLY CLOUDY SKIES AND A
SLIGHT CHANCE OF SHOWERS. THE REST OF THE STATE WILL NOT SEE
FRONTAL PASSAGE.
A SECOND FRONT WITH MORE VIM AND VIGOR IS FORECAST TO REACH KAUAI
LATE WEDNESDAY OR EARLY THURSDAY. THE FRONT WILL THEN MOVE DOWN THE
ISLAND CHAIN TO MAUI COUNTY WHERE IT WILL DISSIPATE BY FRIDAY. A
DESTABILIZING TROUGH ALOFT FORECAST TO MOVE EASTWARD ACROSS THE
ISLANDS WEDNESDAY AND THURSDAY WILL ENHANCE FRONTAL SHOWERS...AND
PREFRONTAL SHOWERS IF ANY. THE ABSENCE OF SUBSIDING AIR ALONG WITH
THE COOLER TEMPERATURES ALOFT ACCOMPANYING THE UPPER LEVEL TROUGH
MAY ALSO SET OFF A FEW THUNDERSTORMS.
SURFACE WINDS BEFORE AND AFTER THE SECOND FRONT WILL NOT BE STRONG.
IT IS POSSIBLE HOWEVER THAT ADVISORY LEVEL SOUTHWESTERLY WINDS WILL
BLOW OVER THE SUMMIT AREAS OF MAUNA KEA AND MAUNA LOA THURSDAY WHEN
THE PRESSURE GRADIENT ALOFT TIGHTENS IN ADVANCE OF THE UPPER TROUGH.
MODERATE SURFACE WINDS WILL VEER OUT OF THE NORTH THEN NORTHEAST
AFTER FRONTAL PASSAGE...SETTLING INTO A TYPICAL EAST-NORTHEAST TRADE
WIND FLOW SOUTH OF A SURFACE HIGH BY THE WEEKEND.
&&
.MARINE...
SURF FROM A NORTHWEST SWELL IS NOT EXPECTED TO REACH ADVISORY LEVEL
TUESDAY.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
