988  
FXUS02 KWBC 050523  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1222 AM EST TUE DEC 05 2017  
 
VALID 12Z FRI DEC 08 2017 - 12Z TUE DEC 12 2017  
   
..OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES
 
 
ABOVE AVERAGE CONFIDENCE IN THE LONGWAVE PATTERN -- RIDGE IN THE  
WEST AND TROUGH IN THE EAST -- BUT BELOW AVERAGE IN THE DETAILS  
DUE TO THE WEAK/QUICK SYSTEMS MOVING THROUGH THE FLOW. THE MODELS  
HAVE WAVERED ON WHICH ONE MAY OR MAY NOT DEVELOP, INCLUDING ALONG  
THE COLD FRONT (NOW IN THE SHORT TERM) THAT WILL BE IN THE  
ATLANTIC AND WILL BE RESPONSIBLE FOR THE INITIAL PUSH OF MODIFIED  
ARCTIC AIR OVER THE NEXT COUPLE OF DAYS. IN ORDER TO LIMIT MODEL  
CHASING, OPTED TO USE THE BROAD CONSENSUS OF THE RECENT RUNS  
(GFS/ECMWF/UKMET/CANADIAN) WITH A TREND TOWARD THE ENSEMBLE MEANS  
BY THE END OF THE PERIOD. THIS SHOULD AT LEAST TAMPER THE  
12-HOURLY CHANGES SEEN IN RECENT 00Z/12Z CYCLES.  
 
   
..WEATHER HIGHLIGHTS
 
 
THE LARGE SCALE PATTERN WILL FAVOR WARM DAYTIME TEMPS OVER MOST OF  
THE WEST (OUTSIDE AREAS CAUGHT UNDER LOW ELEVATION INVERSIONS) AND  
CHILLY READINGS OVER THE EAST. THE PLAINS WILL BE THE DIVIDING  
LINE BETWEEN THESE TWO REGIMES, WITH SOME OSCILLATION IN RESPONSE  
TO SHORTWAVES ALOFT/FRONTAL SYSTEMS. OVER THE WEST AND AT TIMES  
THE PLAINS, SOME MAX TEMP ANOMALIES SHOULD REACH AT LEAST PLUS  
10-15F AT SOME LOCATIONS. SOME READINGS OVER THE EAST MAY BE BELOW  
NORMAL BY A SIMILAR MAGNITUDE, ESPECIALLY IN THE SOUTH.  
 
EXPECT AN EXTENDED PERIOD OF LAKE EFFECT SNOW WITH SIGNIFICANT  
TOTALS POSSIBLE AT SOME LOCATIONS. ON THE NORTHWEST SIDE OF  
GULF/ATLANTIC WAVINESS, LATE WEEK PRECIP WILL EXTEND FROM THE  
SOUTHERN TIER NORTHEASTWARD WITH SOME ACTIVITY POSSIBLY REACHING  
BACK TO THE MID-ATLANTIC/NORTHEAST. HIGHEST AMOUNTS ARE MOST  
LIKELY ALONG THE NC/SC COAST. OVER THE EAST COAST STATES THERE MAY  
BE SOME SNOW IN THE NORTHWEST FRINGE OF THE MOISTURE SHIELD BUT  
THIS WILL NOT GET RESOLVED UNTIL THE SHORT RANGE. FINALLY,  
LOCATIONS FROM THE NORTHERN PLAINS INTO THE APPALACHIANS MAY SEE  
ONE OR MORE PERIODS OF GENERALLY LIGHT PRECIP (MOSTLY SNOW) WITH  
FAST MOVING WAVES/FRONTS. THIS WOULD FAVOR THE WESTERN SLOPES OF  
THE APPALACHIANS WHICH MAY SEE SOME ENHANCEMENT OF SNOWFALL.  
 
FRACASSO/RAUSCH  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page