697  
FXHW01 KWNH 081230  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
729 AM EST THU FEB 08 2018  
 
VALID 00Z FRI FEB 09 2018 - 00Z FRI FEB 16 2018  
 
A BAND OF MID-LATITUDE HEIGHT FALLS MIGRATING EASTWARD WILL GIVE  
WAY TO A SEPARATION IN THE FLOW AS A CLOSED LOW PEELS OFF IN THE  
VICINITY OF 20N/150W BY FRIDAY NIGHT. THIS ULTIMATELY LEADS TO A  
REX BLOCK PATTERN TO THE EAST OF THE HAWAI`IAN ISLAND CHAIN WHILE  
RENEWED UPPER TROUGHING SETS UP OVER THE CENTRAL PACIFIC. THE  
SOUTHERN EXTENT OF THESE LOWER HEIGHTS TAKE AIM AT THE STATE BY  
TUESDAY WITH SUFFICIENT CLUSTERING NOTED IN THE 564-DM ENSEMBLE  
SPAGHETTI PLOTS. THERE IS A GROWING MODEL CONSENSUS THAT ANOTHER  
CLOSED LOW WILL DEVELOP UPSTREAM OF HAWAI`I BY LATE TUESDAY WITH  
OTHER GUIDANCE NOW JOINING THE GFS SOLUTION. BY EARLY WEDNESDAY,  
THERE ARE A FAIR AMOUNT OF 00Z GEFS AND ECMWF ENSEMBLE MEMBERS  
DEPICTING SUCH A NEGATIVE HEIGHT ANOMALY LINGERING OVER THE  
REGION. A VAST MAJORITY OF THE 00Z CMC ENSEMBLE SOLUTIONS REJECT  
THIS IDEA ALTHOUGH THE OPERATIONAL RUN DEPICTS ITS PRESENCE.  
BEYOND THIS PERIOD, THE UPPER LOW IS FORECAST TO DRIFT EASTWARD  
WITH A LOCATION LIKELY JUST EAST OF THE STATE BY NEXT THURSDAY  
AFTERNOON.  
 
IN THE WAKE OF THE FRONTAL PASSAGE, LOW-LEVEL COLD ADVECTION  
SHOULD CONTINUE AS GENERAL NORTHERLY FLOW PERSISTS. IT COULD  
BECOME QUITE BREEZY AT TIMES WITH SUSTAINED WINDS AROUND 20 KNOTS  
EXPECTED. AS A WEAK SURFACE CYCLONE MOVES SOUTHEAST OF THE BIG  
ISLAND BY LATE IN THE WEEKEND, SURFACE WINDS TURN MORE  
EAST-NORTHEASTERLY WITH A DECREASE IN STRENGTH. BY EARLY NEXT  
WEEK, A WARM ADVECTION REGIME ENSUES AHEAD OF A SHARP NORTH/SOUTH  
ORIENTED BAROCLINIC ZONE. DEPENDING ON THE TIMING OF THIS SYSTEM,  
THE NEXT FRONTAL PASSAGE WILL OCCUR BY THE MIDDLE OF NEXT WEEK  
WITH WIND FIELDS QUITE VARIABLE ACROSS HAWAI`I AS THE WAVE SITS  
OVER THE REGION. REGARDING PRECIPITATION THREATS, SCATTERED  
SHOWERS SHOULD BE IN THE PROCESS OF EXITING THE BIG ISLAND WITH  
DRIER CONDITIONS TO PREVAIL IN THE WAKE. THERE COULD BE A THREAT  
FOR SOME DISORGANIZED LIGHT PRECIPITATION OVER THE WEEKEND AS A  
PLUME OF HIGHER PRECIPITABLE WATER PIVOTS BACK OVER THE STATE. A  
MUCH WETTER PERIOD IS LIKELY NEXT WEEK, PARTICULARLY AS THE  
FRONTAL ZONE DRIFTS SLOWLY TOWARD THE EAST. IT SHOULD BE A FAIRLY  
WET SYSTEM AS PRECIPITABLE WATER VALUES NEAR 1.50 INCHES BY THE  
MIDDLE OF THE WEEK.  
 
RUBIN-OSTER  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page