019  
FXUS02 KWBC 111600  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1059 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
 
 
MODEL AGREEMENT DURING THE FORECAST PERIOD WAS FAIRLY GOOD IN THE  
LARGE SCALE, WITH SMALLER FEATURES SUCH AS SHORTWAVES MOVING  
THROUGH THE NORTHERN TIER OF THE U.S. AND THE WEST NOT HANDLED AS  
WELL (PER USUAL). THE DETERMINISTIC GFS AND EC AND THE GEFS AND  
ECENS WERE ALL USED TO DERIVE THE WPC FORECAST THROUGHOUT THE  
PERIOD, WITH INCREASED EMPHASIS APPLIED TO ENSEMBLE MEAN GUIDANCE  
IN THE DAYS 5-7 TIMEFRAME. DESPITE MODEL UNCERTAINTIES IN THE  
DETAILS, FORECAST CONFIDENCE IS HIGH FOR THE THREAT OF HEAVY  
PRECIPITATION FOCUSED IN CALIFORNIA 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. LATER IN THE WEEK,  
PRECIPITATION IS EXPECTED TO SPREAD TO THE PACIFIC NORTHWEST AS  
WELL.  
 
A TEMPERATURE PATTERN CHANGE IS EXPECTED FOR THE NORTH CENTRAL  
TIER OF THE CONUS--EARLY IN THE WEEK, ABOVE NORMAL TEMPERATURES  
ARE EXPECTED DUE TO THE INFLUENCE OF AN UPPER RIDGE ACROSS THE  
GREAT BASIN/NORTHERN ROCKIES, WHICH WILL ERODE BY MIDWEEK. THEN,  
DUE TO INCOMING SHORTWAVES RELATED TO THE LARGE UPPER LOW IN  
CENTRAL CANADA, THE NORTHERN PLAINS AND UPPER MIDWEST ARE LIKELY  
TO SEE BELOW AVERAGE TEMPERATURES LATER NEXT WEEK. THE NORTHEAST  
MAY EXPERIENCE PERIODS OF BELOW NORMAL TEMPERATURES FOR THE SAME  
REASON.  
 
TATE/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  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page