FXHW60 PHFO 100557
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
800 PM HST WED DEC 9 2009
.SYNOPSIS...
A HIGH PRESSURE RIDGE HAS SHIFTED OVER THE ISLANDS CAUSING WINDS
TO WEAKEN. TRADE WINDS WILL STRENGTHEN A BIT FRIDAY BUT THEN BECOME
LIGHT AGAIN THIS WEEKEND. THE AIR MASS IS DRY AND STABLE WITH MOSTLY
SUNNY DAYS EXPECTED THROUGH THIS WEEKEND. CHANCES OF FRONTAL SHOWERS
INCREASE DURING THE FIRST HALF OF NEXT WEEK.
&&
.DISCUSSION...
THE CURRENT FORECAST LOOKS GENERALLY ON TRACK. EXPECTING ANOTHER
MOSTLY CLEAR NIGHT...GIVING WAY TO SEA BREEZES AND A FEW ISOLATED
AFTERNOON CLOUDS THU. A EQUATORWARD SHIFTED NEARLY ZONAL POLAR JET
WILL KEEP A SERIES OF MID LATITUDE SYSTEMS MOVING E JUST N OF THE
STATE. THIS WILL ALLOW TRADES AND ISOLATED WINDWARD SHOWERS TO
RETURN TEMPORARILY FRI AS HIGH PRESSURE MIGRATES E ALONG 30N. INTO
THE WEEKEND WINDS VEER AND DECREASE ONCE AGAIN WITH A DRY DIURNAL
WEATHER PATTERN RETURNING. THE LOW RIDING JET TRACK WILL MAINTAIN
GENERALLY LOWERED HEIGHTS OVER MUCH OF THE N PACIFIC SUGGESTING WEAK
PRESSURE GRADIENTS AND CONTINUED LIGHT WINDS LOCALLY INTO EARLY NEXT
WEEK. BEST SHOWER CHANCES COME WITH THE POTENTIAL FOR WEAKENING
FRONTAL BOUNDARIES GRAZING THE STATE FROM MON THROUGH THE MIDDLE OF
NEXT WEEK.
&&
.PREVIOUS DISCUSSION.../ISSUED 400 PM HST WED/
A FEW AFTERNOON CLOUDS MATERIALIZED AIDED BY THE AFTERNOON HEATING
OF THE LAND BUT ANY SHOWERS WERE INSIGNIFICANT. OTHERWISE
SKIES ARE MOSTLY CLEAR OVER THE AREA. EXTREMELY LOW TEMPERATURE
INVERSION AGAIN JUST UNDER 3000 FEET AND PRECIPITABLE WATER ONLY 0.8
INCH. A REPETITIOUS WEATHER PATTERN IS EXPECTED INTO THE WEEKEND
WITH NEGLIGIBLE TO NON-EXISTENT SHOWER ACTIVITY DESPITE SOME
AFTERNOON CLOUD FORMATION FROM SEA BREEZES AND AFTERNOON HEATING OF
THE LAND. THIS WILL BE FOLLOWED BY CLEAR SKIES AT NIGHT AND COOL
TEMPERATURES. AFTERNOON DEWPOINT TEMPERATURES WERE PLEASANT IN THE
60S.
TRADES WILL AGAIN BE LIGHT WITH AFTERNOON SEA BREEZES THURSDAY SINCE
THE SURFACE RIDGE IS OVER OR JUST NORTH OF THE ISLANDS,
FIRMER TRADE WINDS WILL RETURN FOR ONLY FRIDAY WHEN A SURFACE HIGH
PASSES BY TO THE NORTH...BUT THEN THE SURFACE RIDGE WILL SHIFT BACK
OVER THE ISLANDS THIS WEEKEND PRODUCING GENTLE SOUTHEASTERLY OR
VARIABLE WINDS.
THE GFS MODELS A FRONT THAT APPROACHES AND THEN STALLS NORTH OF THE
ISLANDS MONDAY WHILE THE EUROPEAN MODEL PUSHES IT SLOWLY THROUGH
TUESDAY AND WEDNESDAY. DIFFERENCES REST IN THE EVOLUTION AND
MOVEMENT OF THE LOW IN THE NORTH PACIFIC. THE GFS MODELS A SECONDARY
LOW AND FINALLY DOES PUSH A COLD FRONT THROUGH A DAY
LATER...WEDNESDAY INTO THURSDAY. THEREFORE CONFIDENCE STILL SOMEWHAT
LOW AND THE NEW FORECAST PACKAGE DOES NOT MENTION ANYTHING
SIGNIFICANT REGARDING THE FRONT.
&&
.MARINE...
THE NORTHWEST SWELL HAS DECREASED THROUGH THE DAY BUT REMAINS
SIGNIFICANT THIS EVENING. THE HIGH SURF WARNINGS HAVE BEEN DROPPED
THIS AFTERNOON IN FAVOR OF ADVISORIES FOR TONIGHT AND THURSDAY.
ANOTHER NORTHWEST SWELL WILL PRODUCE SURF NEAR ADVISORY LEVEL THIS
WEEKEND FOR NORTH FACING SHORES. A STEADY INFLUX OF NW SWELL WILL
KEEP SURF AT MODERATE TO OCCASIONALLY HIGH LEVELS WELL INTO NEXT
WEEK. S FACING SHORES WILL BE LOOKING MORE TYPICAL OF DECEMBER
REMAINING PRETTY MUCH FLAT.
SMALL CRAFT ADVISORIES DUE TO THE NW SWELL THROUGH TONIGHT.
&&
.AVIATION...
VFR CONDITIONS EXPECTED THROUGH THU. ONLY ISOL BKN CIGS BTN 035/040
EXPECTED. FU HZ AROUND THE BIG ISLAND MAY PRODUCE PATCHY VFR VIS DUE
TO THE LIGHT WINDS AND POOR MIXING.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST FRIDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-OAHU
KOOLAU-MOLOKAI-MAUI WINDWARD WEST-MAUI CENTRAL VALLEY-WINDWARD
HALEAKALA.
SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-OAHU LEEWARD WATERS-KAIWI CHANNEL-MAUI
COUNTY WINDWARD WATERS-MAUI COUNTY LEEWARD WATERS-ALENUIHAHA
CHANNEL-BIG ISLAND WINDWARD WATERS-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
&&
$$
PUBLIC/AVIATION...DEJESUS
MARINE...DEJESUS/HOAG
PREVIOUS...HOAG
