929  
FXUS02 KWBC 150343  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1042 PM EST MON JAN 14 2019  
 
VALID 12Z FRI JAN 18 2019 - 12Z TUE JAN 22 2019  
 
...FRIGID AIR FROM THE CENTRAL U.S. THROUGH THE NORTHEAST SETS THE  
STAGE FOR ANOTHER MAJOR CENTRAL TO EASTERN U.S. SNOWSTORM...  
 
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THE MEDIUM RANGE PERIOD  
OVER MUCH OF THE NATION, BOLSTERING FORECAST CONFIDENCE TO ABOVE  
NORMAL LEVELS. WPC CONTINUITY IS WELL MAINTAINED WITH THE WPC  
PRODUCT SUITE PRIMARILY DERIVED FROM A COMPOSITE BLEND OF WELL  
CLUSTERED GUIDANCE FROM THE 18 UTC GFS/GEFS MEAN AND 12 UTC  
ECMWF/ECMWF ENSEMBLE MEAN.  
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
AMPLIFIED SOUTHERN STREAM MID-UPPER LEVEL TROUGH ENERGY/HEIGHT  
FALLS DIGS THROUGH THE SOUTHWEST FRIDAY WITH POOLED MOISTURE AND  
PRECIPITATION WORKING THROUGH THE INTERMOUNTAIN WEST/GREAT  
BASIN/ROCKIES WITH WINDY CONDITIONS AND VALLEY RAIN/MOUNTAIN SNOW.  
SNOW LEVELS WILL FALL AS HEIGHTS LOWER WHICH WILL TURN SOME LOWER  
ELEVATIONS OVER TO SNOW AS PRECIPITATION DIMINISHES SATURDAY.  
PACIFIC STORM SYSTEMS RELOAD FARTHER TO THE NORTH LATER FOR THE  
HOLIDAY WEEKEND TO THEN FOCUS AN ASSOCIATED HEAVY PRECIPITATION  
THREAT INTO/ACROSS THE NORTHWEST.  
 
DOWNSTREAM SURGES OF FRIGID ARCTIC AIR INTO THE CENTRAL U.S.  
FRIDAY THROUGH THE WEEKEND OCCUR AS THE NORTHERN STREAM AMPLIFIES  
AROUND A HUDSON BAY UPPER VORTEX. A LEAD SYSTEM WILL SPREAD SOME  
WINTERY WEATHER OVER THE NORTHEAST FRIDAY. UPSTREAM, A MORE ROBUST  
SYSTEM EJECTING FROM THE WEST ORGANIZES OVER THE SOUTH-CENTRAL  
PLAINS WITH INCREASED LEAD GULF OF MEXICO MOISTURE AND LIFT UP  
THROUGH THE EAST-CENTRAL U.S. SATURDAY AS AN ARCTIC FRONT TO THE  
NORTH PUSHES THROUGH THE NORTHEAST. AS PRECIPITATION OVERRUNS THE  
ARCTIC AIRMASS TO THE NORTH, HEAVY SNOW WILL SPREAD OUT OF THE  
CENTRAL PLAINS THROUGH THE MIDWEST/OHIO VALLEY THEN  
MID-ATLANTIC/NORTHEAST THROUGH THE HOLIDAY WEEKEND ALONG WITH SOME  
THREAT OF BLIZZARD CONDITIONS IN THE TIGHT PRESSURE GRADIENT  
AROUND A MAIN LOW THAT LIFTS THROUGH THE EASTERN U.S. AND  
OFFSHORE. MEANWHILE, HEAVY WARM-SECTOR RAINS/CONVECTION MOVE  
THROUGH THE SOUTH/SOUTHEAST AND A TRANSITION ZONE BETWEEN SNOW AND  
RAIN WILL INCLUDE SIGNIFICANT SLEET AND FREEZING RAIN. PLEASE  
CONSULT WPC DAY 4-7 QPF AND WINTER WEATHER OUTLOOK FOR A  
PROBABILISTIC ASSESSMENT OF THE SIGNIFICANT WINTER WEATHER THREAT.  
 
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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