942  
FXUS02 KWBC 110633  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
133 AM EST FRI JAN 11 2019  
 
VALID 12Z MON JAN 14 2019 - 12Z FRI JAN 18 2019  
   
..CALIFORNIA HEAVY PRECIPITATION PATTERN NEXT WEEK
 
 
   
..OVERVIEW
 
 
STEADILY PROGRESSIVE AND AMPLIFIED PACIFIC FLOW WILL BRING A  
SERIES OF SIGNIFICANT STORMS TO THE WEST COAST NEXT WEEK. AS THESE  
SYSTEMS MOVE EASTWARD, SPLIT FLOW WILL EMERGE AROUND AN AMPLIFIED  
DOWNSTREAM GREAT BASIN/ROCKIES UPPER RIDGE. NORTHERN STREAM ENERGY  
WILL AMPLIFY AS IT ENTERS BROAD CYCLONIC UPPER-LEVEL FLOW EAST OF  
THE RIDGE, WITH FREQUENT SHORTWAVES AND MEAN UPPER TROUGHING FROM  
THE UPPER MIDWEST TO THE NORTHEAST. LEAD MID-ATLANTIC COASTAL LOW  
DEVELOPMENT THIS WEEKEND WILL TRACK NORTHEASTWARD OVER THE WESTERN  
ATLANTIC AND CANADIAN MARITIMES EARLY NEXT WEEK. MEANWHILE, AN  
ACTIVE WEST COAST WILL FEATURE AMPLIFIED TROUGH/UPPER LOWS TO  
ESPECIALLY THREATEN CALIFORNIA ALL NEXT WEEK.  
 
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A  
COMPOSITE MULTI MODEL AND ENSEMBLE BLEND EARLY NEXT WEEK, WITH  
INCREASED EMPHASIS APPLIED TO ENSEMBLE MEAN GUIDANCE IN THE DAYS  
5-7 TIMEFRAME AMID QUICKLY GROWING DETERMINISTIC GUIDANCE RUN TO  
RUN VARIANCE. DESPITE THIS UNCERTAINTY, FORECAST CONFIDENCE IS  
GOOD IN THE OVERALL PATTERN INCLUDING A THREAT OF HEAVY  
PRECIPITATION WITH CALIFORNIA FOCUS NEXT WEEK.  
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
A LEAD COASTAL LOW PRESSURE SYSTEM LIFTING OFF THE EASTERN  
SEABOARD MON/TUE WILL BE A MARITIME THREAT AS THE SYSTEM DEEPENS  
OFFSHORE. THE WEST COAST WILL REMAIN QUITE ACTIVE GIVEN THE RAPID  
FREQUENCY OF SHORTWAVE ENERGIES AND FRONTAL SYSTEMS. THE HEAVIEST  
PRECIPITATION (LOW ELEVATION RAIN AND MOUNTAIN SNOW) WILL BE  
FOCUSED ACROSS CALIFORNIA, WITH MULTIPLE ROUNDS OF PRECIPITATION  
POSSIBLE THROUGH THE FORECAST PERIOD. TOTAL PRECIPITATION AMOUNTS  
OVER THE PERIOD COULD BE HEAVY, WITH UPSLOPE FLOW ENHANCING QPF TO  
4 TO 8 INCHES IN THE SIERRA AND COASTAL RANGES.  
 
SCHICHTEL  
 
WPC MEDIUM RANGE 500 MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDEXES ARE FOUND AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 
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