307  
FXUS02 KWBC 191558  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1057 AM EST TUE FEB 19 2019  
 
VALID 12Z FRI FEB 22 2019 - 12Z TUE FEB 26 2019  
 
...MULTI-DAY HEAVY RAINFALL/FLOODING THREAT FROM THE LOWER  
MISSISSIPPI/TENNESSEE/OHIO VALLEYS TO THE SOUTHERN/CENTRAL  
APPALACHIANS THROUGH SATURDAY...  
 
...SIGNIFICANT SNOW THREAT LIFTS FROM THE SOUTHWEST AND  
SOUTH-CENTRAL ROCKIES STATES FRIDAY THROUGH THE PLAINS/UPPER  
MIDWEST AND GREAT LAKES/NORTHEAST THIS WEEKEND...  
 
   
..PATTERN OVERVIEW AND WEATHER HIGHLIGHTS/HAZARDS
 
 
A FAVORABLE CORRIDOR FOR A MULTI-DAY HEAVY RAIN/TRAINING EPISODE  
WILL PERSIST FROM THE LOWER MS/TN/OH VALLEYS TO THE  
SOUTHERN/CENTRAL APPALACHIANS AND MID-ATLANTIC THROUGH SATURDAY.  
FLOODING/RUNOFF ISSUES WILL BE FUELED BY HIGHLY ANOMALOUS MOISTURE  
CHANNELING INTO A WAVY FRONTAL ZONE UNDER FAVORABLE JET SUPPORT  
INITIALLY, THEN DEEPER WEEKEND CYCLO/FRONTOGENESIS.  
 
AN AMPLIFIED UPPER TROUGH WILL SUPPORT TERRAIN ENHANCED HEAVY  
SNOWS OVER THE SOUTHWEST AND THE SOUTH-CENTRAL ROCKIES STATES ON  
FRIDAY. THE TROUGH LIFTS THROUGH THE CENTRAL AND NORTHEAST U.S.  
THIS WEEKEND OVERTOP AN AMPLIFIED AND SLOW TO ERODE  
BAHAMAS/SOUTHEAST UPPER RIDGE. THIS SYSTEM WILL BRING A THREAT FOR  
SIGNIFICANT ACCUMULATING SNOW WITH SOME ICING POSSIBLE WITH A  
DEEPENING SURFACE LOW TRACKING FROM THE PLAINS TO THE UPPER  
MIDWEST/GREAT LAKES/NEW ENGLAND. MODELS HAVE COME INTO BETTER  
AGREEMENT COMPARED TO PREVIOUS RUNS ON THE STRENGTH OF THE SURFACE  
LOW, WITH MOST DETERMINISTIC SOLUTIONS ADVERTISING A SURFACE LOW  
BY 12Z SATURDAY IN THE 980S OVER THE UPPER GREAT LAKES. THIS WOULD  
LIKELY RESULT IN GUSTY WINDS AND POTENTIAL BLIZZARD CONDITIONS  
ACROSS THE UPPER MIDWEST AND GREAT LAKES THIS WEEKEND.  
 
TROUGHING OUT WEST GETS REINFORCED THROUGH THE MEDIUM RANGE PERIOD  
THANKS TO A BLOCKING RIDGE SITUATED IN THE GULF OF ALASKA AND  
EASTERN PACIFIC. A COUPLE OF SHORTWAVES DIG SOUTHWARD THROUGH THE  
NORTHWEST THIS WEEKEND/EARLY NEXT WEEK, ALBEIT SHOULD BE LESS  
AMPLIFIED THAN THE LEAD SYSTEMS. THIS SHOULD CONTINUE AN UNSETTLED  
WEATHER PATTERN ACROSS THE PACIFIC NORTHWEST AND INTO THE  
INTERMOUNTAIN WEST, WITH THE BEST CHANCE FOR ACCUMULATING SNOWFALL  
IN THE WASHINGTON/OREGON CASCADES.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT AND PREFERENCES
 
 
MODELS AND ENSEMBLE SOLUTIONS CONTINUE TO SHOW VERY GOOD  
CLUSTERING AT THE MID-LARGER SCALES THROUGH THE MEDIUM RANGE  
PERIOD. THE MORNING UPDATE TO THE WPC PROGS FAVORED A MAJORITY  
BLEND OF THE LATEST RUNS OF THE GFS/ECMWF, WITH SMALLER  
CONTRIBUTIONS FROM THE GEFS/ECMWF ENSEMBLE MEANS. THIS MAINTAINS  
EXCELLENT WPC CONTINUITY WITHIN A PATTERN WITH ABOVE NORMAL  
PREDICTABILITY.  
 
SANTORELLI/SCHICHTEL  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION AND WINTER WEATHER OUTLOOK  
PROBABILITIES 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  
 

 
 
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