739  
FXUS02 KWBC 130656  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
155 AM EST SUN JAN 13 2019  
 
VALID 12Z WED JAN 16 2019 - 12Z SUN JAN 20 2019  
   
..CALIFORNIA HEAVY PRECIPITATION
 
   
..COLD AIR SURGES THROUGH THE NORTH-CENTRAL U.S
 
   
..CENTRAL TO EASTERN U.S. HEAVY RAIN/SNOW THREAT NEXT WEEKEND
 
 
 
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
WHILE THE OVERALL LARGER SCALE FLOW PATTERN EVOLUTION REMAINS  
REASONABLY WELL SUPPORTED IN GUIDANCE, AN UNCERTAIN SPLIT OF  
SMALLER SCALE ENERGIES OVER THE EASTERN PACIFIC AND SUBSEQUENT  
PROGRESSION INLAND ACROSS NORTH AMERICA CONTINUES TO OFFER  
SIGNIFICANT RUN TO RUN DIFFERENCES IN DETERMINISTIC GUIDANCE FROM  
SHORT THROUGH MEDIUM RANGE TIME SCALES. ACCORDINGLY, THE WPC  
MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A BLEND OF  
MORE COMPATABLE GEFS/NAEFS/ECMWF ENSEMBLE MEANS. THIS HOLDS  
REASONABLE WPC CONTINUITY.  
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
IN THIS SOLUTION, AMPLE SOUTHERN STREAM MID-UPPER LEVEL TROUGH  
ENERGY/HEIGHT FALLS IMPACT CALIFORNIA AND TO A LESSER EXTENT THE  
PACIFIC NORTHWEST WED/THU TO PRODUCE ADDITIONAL HEAVY  
RAIN/MOUNTAIN SNOWS. A MODERATING SWATH OF ACTIVITY IN THIS STREAM  
WORKS INLAND ACROSS THE INTERMOUNTAIN WEST AND ROCKIES INTO FRIDAY  
BEFORE THE APPROACH OF AN AMPLIFIED PACIFIC TROUGH OVER THE  
NORTHEASTERN PACIFIC SWITCHES FOCUS TO THE NORTHWEST NEXT WEEKEND.  
 
DOWNSTREAM, GLANCING BLOWS OF COLD CANADIAN AIR PAST MIDWEEK OVER  
THE CENTRAL TO EASTERN U.S. NORTHERN TIER BECOME MORE  
SIGNIFICANT/LONGER LASTING AND INCREASINGLY SOUTHWARD SURGING  
LATER WEEK INTO NEXT WEEKEND WITH NORTHERN STREAM AMPLIFICATION.  
THIS OCCURS AS AMPLE SOUTHERN STREAM ENERGIES EJECT UNDERNEATH  
FROM THE WESTERN U.S. TO SPAWN S-CENTRAL TO EASTERN U.S.  
CYCLOGENESIS/FRONTOGENESIS. DEEPENING MOISTURE INFLUX INTO THE  
SYSTEM AND OVERRUNNING THE COLD AIRMASS SPILLED OVERTOP WOULD  
COMBINE WITH DYNAMICS TO FUEL AN INCREASINGLY ROBUST  
MOISTURE/PRECIPITATION SHIELD THAT OFFERS A SIGNIFICANT THREAT FOR  
HEAVY WARM SECTOR RAINS/CONVECTION AND A WIDESPREAD SWATH OF HEAVY  
SNOW/ICE TO THE NORTH.  
 
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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