869  
FXUS02 KWBC 040657  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
157 AM EST SUN NOV 04 2018  
 
VALID 12Z WED NOV 07 2018 - 12Z SUN NOV 11 2018  
 
...GUIDANCE/PREDICTABILITY ASSESSMENT AND WEATHER  
HIGHLIGHTS/THREATS...  
 
IT REMAINS EVIDENT THAT BROAD CYCLONIC FLOW ALOFT WILL REMAIN  
ANCHORED OVER MOST OF THE LOWER 48 THIS WEEK AS EMBEDDED SYSTEMS  
PASS THROUGH THE LARGE SCALE MEAN TROUGH. A DEEP LEAD LOW REACHES  
EASTERN CANADA WED AS A TRAILING COLD FRONT/PRECIPITATION FOCUS  
WORKS INTO THE WESTERN ATLANTIC AND FLORIDA/NORTHERN GULF OF  
MEXICO. FORECAST CONFIDENCE IS ABOVE NORMAL FOR THIS SCENARIO.  
PREFER A COMPOSITE GUIDANCE SOLUTION.  
 
GUIDANCE REMAINS MORE VARIED LATER WEEK INTO NEXT WEEKEND, BUT  
THERE IS AN INCREASING SIGNAL FROM THE 00 UTC UKMET AND 12/00 UTC  
ECMWF AND ECMWF ENSEMBLES THAT UPSTREAM ENERGIES DIGGING INTO THE  
MEAN TROUGH WILL DIVE MORE ERNESTLY THROUGH THE UNSETTLED WEST TO  
THEN EJECT AND SPIN UP ANOTHER DEEPENING LOW THU/FRI OVER THE  
EAST-CENTRAL U.S. THE GFS/FV3 AND GEFS ENSEMBLES MAY IN CONTRAST  
BE UNDER AMPLIFIED/TOO PROGRESSIVE WITH THE PATTERN GIVEN RECENT  
TRENDS AND AMPLIFIED FLOW UPSTREAM EMINATING FROM THE PACIFIC.  
PREFER A SOLUTION CLOSEST TO THE ECMWF ENSEMBLE MEAN GIVEN  
LINGERING MODEL VARIANCE.  
 
ACCORDINGLY, EXPECT A THREAT FOR WIDESPREAD HEAVIER PRECIPITATION  
AHEAD/AROUND THIS SECOND MAIN SYSTEM, FIRST WITH DYNAMICS OVER THE  
WEST INTO TERRAIN AND DOWNSTREAM WITH SYSTEM GENESIS AS FUELED BY  
INFLUX OF DEEPENED MOISTURE FROM THE ATLANTIC AND GULF OF MEXICO.  
THE MAIN LOW WOULD SUBSEQUENTLY TRACK UP TO EASTERN CANADA BY NEXT  
SATURDAY AS ITS TRAILING COLD FRONT PROGRESSES UNDERNEATH ACROSS  
THE CENTRAL THEN EASTERN STATES. THIS MAY ALSO SPREAD SOME WINTRY  
WEATHER/SWATH OF HEAVIER SNOW ACROSS THE CENTRAL PLAINS AND ONWARD  
TO THE NORTH OF THE SURFACE LOW TRACK, ESPECIALLY THU/FRI OVER THE  
U.S. AS COLD POST-SYSTEM CANADIAN HIGH PRESSURE SURGES INTO/ACROSS  
THE LOWER 48.  
 
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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