285  
FXUS02 KWBC 020638  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
238 AM EDT FRI NOV 02 2018  
 
VALID 12Z MON NOV 05 2018 - 12Z FRI NOV 09 2018  
 
...GUIDANCE/PREDICTABILITY ASSESSMENT AND PATTERN OVERVIEW/WEATHER  
THREATS...  
 
THE 00 UTC GFS TRENDED STRONGLY TOWARD THE 12 UTC ECMWF, BUT  
DIFFERENCES AND RUN-RUN VARIANCE REMAINS WITH SMALLER SCALE  
DETAILS. THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED  
FROM A BLEND OF THESE MODELS AND RESPECTIVE/COMPATABLE ENSEMBLE  
MEANS.  
 
BROAD CYCLONIC FLOW/UPPER-LEVEL TROUGHING SPREADS OVER MUCH OF THE  
LOWER 48 NEXT WEEK BETWEEN UPPER RIDGES THAT HOLD OVER THE EASTERN  
PACIFIC AND WESTERN ATLANTIC. THE TROUGH WILL BE REINFORCED BY A  
SERIES OF SHORTWAVES ORIGINATING IN THE NORTH PACIFIC THAT  
POTENTIALLY INTERACT/AMPLIFY OVER THE PLAINS WITH ADDITION OF  
SHORTWAVE ENERGY OF POLAR/ARCTIC ORIGIN. THERE IS AN INCREASING  
THREAT FOR DEEPENING LOW PRESSURE TO LIFT INTO THE MIDWEST/GREAT  
LAKES BY NEXT TUESDAY THEN EASTERN CANADA MID-LATER WEEK. THIS  
WOULD FORCE A PRECIPITATION FOCUSING FRONTAL SYSTEM ACROSS THE  
CENTRAL THEN EASTERN STATES. COLDER CANADIAN AIR TO DIG INTO LOWER  
48 IN THE WAKE OF SYSTEM PASSAGE SUPPORTS ORGANIZED SNOW ON THE  
NORTHWEST SYSTEM PERIPHERY, MAINLY OVER THE UPPER MIDWEST.  
 
IN THIS PATTERN MUCH OF THE EAST-CENTRAL U.S. WILL SEE MORE  
WIDESPREAD PRECIPITATION EARLY NEXT WEEK AS DYNAMIC SUPPORT ALOFT  
COMBINES WITH INCREASINGLY FAVORAVBLE RETURN THETAE ADVECTION WITH  
STORM/FRONTAL ADVANCE AND DEEPENING. AN EXPANDING AREAS OF RAIN  
WILL SPREAD NORTHEASTWARD AHEAD OF THE SYSTEM MON-WED WITH AN INCH  
OR MORE OF RAIN POSSIBLE OVER A LARGE AREA. THIS INCLUDES THE  
MISSISSIPPI/OHIO/TENNESSEE VALLEYS, MIDWEST/GREAT LAKES, AND THE  
EAST. OVER THE EAST, A LINGERING LEAD STATIONARY FRONT MAY  
MEANWHILE PUSH BACK TOWARD THE COAST TO FURTHER BRING POTENTIAL  
FOR PRECIPITATION BACK TO THE I-95 CORRIDOR FROM THE SOUTHEAST ALL  
THE WAY NORTHWARD TO NEW ENGLAND. LATER WEEK MORE MODEST  
PRECIPITATION MAY RENEW OVER THE S-CENTRAL/SOUTHERN U.S./GULF OF  
MEXICO AS ADDITIONAL SHORTWAVE ENERGIES DIG INTO THE BASE OF THE  
LONGWAVE TROUGH ALOFT AND FEED UPON MOISTURE POOLED ALONG A  
STALLED WAVY/TRAILING FRONT. MEANWHILE, PERIODS OF MODERATE RAINS  
AND HIGHER ELEVATION SNOWS WILL BE POSSIBLE FOR THE PACIFIC  
NORTHWEST EARLY-LATER NEXT WEEK, WITH SNOWS SPREADING TO THE  
ROCKIES AS UPPER SHORTWAVES AND SURFACE FRONTS TRAVERSE THE REGION  
TO THE LEE OF THE EASTERN PACIFIC UPPER RIDGE.  
 
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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