946
FXHW01 KWNH 080759
PMDHI
HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EST SUN DEC 08 2024
VALID 00Z MON DEC 09 2024 - 00Z MON DEC 16 2024
GUIDANCE HAS BEEN CONSISTENT AND AGREEABLE WITH THE OVERALL LOW
LEVEL PATTERN FOR THE COMING WEEK. AN INITIAL SURFACE TROUGH OVER
THE AREA AND A FRONT APPROACHING FROM THE NORTHWEST BUT NOT QUITE
REACHING THE ISLANDS WILL FAVOR LIGHT TO MODERATE TRADES THROUGH
SUNDAY, LEADING TO A MIXED FOCUS FOR SHOWERS. THEN STRONGER TRADES
WILL PREVAIL FROM MONDAY ONWARD AS MULTIPLE SURFACE HIGHS PASS BY
TO THE NORTH, WITH RELATIVELY HIGHER WIND SPEEDS TENDING TO BE IN
THE WEDNESDAY-THURSDAY TIME FRAME BUT POSSIBLY EXTENDING INTO
FRIDAY. THIS PATTERN WILL RESUME A MORE PRONOUNCED
WINDWARD/MOUNTAIN SHOWER FOCUS.
HOWEVER, GUIDANCE CONTINUES TO VARY SOMEWHAT FOR SPECIFICS ALOFT
ALONG WITH CORRESPONDING EFFECTS ON MOISTURE. DYNAMICAL MODELS
STILL PULL OFF WEAK ENERGY ALOFT TO FORM AN UPPER LOW TO THE
SOUTHWEST/SOUTH OF THE ISLANDS NEAR 10N LATITUDE BY MID-LATE WEEK,
BUT WITH CONTINUED EAST-WEST SPREAD. THE CMC/CMCENS MEAN HOLD THE
FEATURE FARTHEST EAST WHILE THE ECMWF/ECENS MEAN SHOW MORE
RETROGRESSION. MACHINE LEARNING (ML) GUIDANCE HAS SHOWN MULTI-DAY
OSCILLATIONS, REFLECTING AN INTERMEDIATE TIMING A COUPLE DAYS AGO,
HANGING ON TO THE EASTERN SIDE OF THE SPREAD 24 HOURS AGO, AND NOW
RETURNING TO A SOLUTION SIMILAR TO OR JUST A TAD SLOWER THAN THE
00Z ECMWF. IT IS STILL A CLOSE CALL AS TO WHETHER THE NORTHERN
PERIPHERY OF ENHANCED MOISTURE REACHES THE BIG ISLAND AND VICINITY
AROUND LATE WEEK, WITH THE ECMWF/ECENS MEAN SHOWING MORE MOISTURE
THAN THE GEFS MEAN. AT THE VERY LEAST, THE DYNAMICAL AND ML
MODELS OFFER MINIMAL SUPPORT FOR THE 00Z GFS SOLUTION OF AN OPEN
TROUGH ALOFT JUST EAST OF THE STATE BY SATURDAY AND PERSISTENCE OF
FAIRLY HIGH PWATS THROUGH THE WEEKEND. THUS WOULD RECOMMEND AN
AVERAGE OF THE ECMWF/ECENS MEAN AND GEFS MEAN FOR THE UPPER LEVEL
AND MOISTURE FORECASTS.
RAUSCH
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