914  
FXUS02 KWBC 260712  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
211 AM EST FRI JAN 26 2018  
 
VALID 12Z MON JAN 29 2018 - 12Z FRI FEB 02 2018  
   
..GUIDANCE AND PREDICTABILTY ASSESSMENT
 
 
THE 18/00 UTC GFS AND 12/00 UTC ECMWF ARE WELL POSITIONED WITHIN  
THE OVERALL FORECAST DISTRIBUTION OUTLINED BY THEIR ENSEMBLES IN A  
MEDIUM RANGE FORECAST PATTERN WITH SLIGHTLY BETTER THAN AVERAGE  
FORECAST SPREAD AND IMPLIED PREDICTABILITY. A FAVORED COMPOSITE  
BLEND SEEMS TO OFFER A REASONABLE DEPICTION OF THE FLOW DESPITE  
UNRESOLVED SMALLER SCALE TIMING AND AMPLITUDE DIFFERENCES IN  
GENERALLY PROGRESSIVE FLOW THAT MAY GRADUALLY DEAMPLIFY NEXT WEEK.  
THIS SCENARIO MAINTAINS GOOD WPC DETERMINISTIC AND PROBABILISTIC  
CONTINUITY OVERALL.  
   
..PATTERN OVERVIEW AND WEATHER HIGHLIGHTS/THREATS
 
 
AMPLIFIED MID-UPPER LEVEL TROUGHING OVER THE HALF OF THE NATION  
MONDAY STEADILY WORKS OFFSHORE INTO THE WRN ATLANTIC TUE/WED. THIS  
WOULD USHER IN ANOTHER COLD SURGE DUG DOWN ACROSS THE CENTRAL AND  
ERN US AND ACT TO ENHANCE GREAT LAKE SNOWS IN THE WAKE OF LEAD  
WAVY FRONTAL SYSTEM PASSAGE. THE WPC COMPOSITE SOLUTION OFFERS A  
MODEST LEAD COASTAL LOW AND SEABOARD WEATHER THREAT...ALBEIT WITH  
SOME POTENTIAL FOR MORE ORGANIZED DEVELOPMENT AS PER SOME ENSEMBLE  
MEMBERS THAT WOULD INCREASE THE SNOW THREAT FROM THE ERN  
MID-ATLANTIC INTO NEW ENGLAND.  
 
MEANWHILE...PACIFIC HEIGHT FALLS/SYSTEM APPROACH INTO THE NWRN  
STATES WILL INCREASE POTENTIAL FOR HEAVIER PCPN WITH TERRAIN  
ENHANCED RAINS/ELEVATION SNOWS EARLY NEXT WEEK AND AGAIN THROUGH  
MID-LATE NEXT WEEK WITH ADDITIONAL SYSTEM APPROACHES AND INLAND  
PROGRESSION IN LESS AMPLIFIED/MORE UNCERTAIN PROGRESSIVE FLOW.  
DYNAMICS AND ONSHORE FETCH HAS THE POTENTIAL TO YIELD MULTIPLE  
INCHES OF RAIN INTO FAVORED TERRAIN OF THE PACIFIC NW AND LOWERING  
SNOW LEVELS IN THE WAKE OF THE LEAD SYSTEM AND WITH ADVENT OF  
LATER FOLLOW-UP ENERGIES COULD LEAD TO MULTIPLE FEET OF MOUNTAIN  
SNOWS INLAND OVER THE NWRN US.  
 
IN ADVANCE OF THIS...A WARMING/STABLE MID-UPPER LEVEL RIDGE IS  
SLATED TO PROGRESS FROM THE WRN US MON EASTWARD TO THE ERN  
SEABOARD BY THU AND PROVIDE ANOTHER TASTE OF SPRING AS LEAD LOWER  
ATMOSPHERIC WARM AIR ADVECTION AND AN INCREASING RETURN FLOW OF  
GULF OF MEXICO MOISTURE AHEAD OF CENTRAL NOAM CYCLOGENESIS AND  
FRONTOGENESIS WOULD BE AVAILABLE TO FUEL AN EMERGING CENTRAL TO US  
PRECIPITATION PATTERN. THIS WOULD INCLUDE POTENTIAL FOR SOME  
HEAVIER CONVECTION OVER MID-SRN LATITUDES AND SNOWS OVER THE  
COOLER NRN TIER STATES MORE UNDER THE INFLUENCE OF PASSING NRN  
STREAM IMPULSES AND LOWER LEVEL COLD AIR RETURN.  
 
SCHICHTEL  
 

 
 
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