515  
FXUS02 KWBC 081600  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1200 PM EDT MON APR 08 2019  
 
VALID 12Z THU APR 11 2019 - 12Z MON APR 15 2019  
 
...MAJOR WINTER STORM TRACKING FROM THE CENTRAL PLAINS INTO UPPER  
GREAT LAKES THU-FRI...  
...HEAVY RAINFALL THREAT FROM EASTERN TEXAS/LOWER MISSISSIPPI  
VALLEY NORTHEASTWARD DURING THE WEEKEND...  
 
   
..OVERVIEW AND GUIDANCE ASSESSMENT/PREFERENCES
 
 
GUIDANCE CONTINUES TO SHOW A MODERATELY PROGRESSIVE PATTERN  
CONSISTING OF EMBEDDED STRONG/IMPACTFUL SYSTEMS. THE FORECAST  
BASED ON NEW 00Z-06Z GUIDANCE FOLLOWS A SIMILAR APPROACH TO  
CONTINUITY, MAINTAINING GREATER WEIGHT TOWARD ECMWF/ECMWF MEAN  
SOLUTIONS THAT SHOW GREATER/SLOWER DIGGING OF SHORTWAVE ENERGY  
OVER THE WEST VERSUS GFS RUNS LATE THIS WEEK FOLLOWED BY SOMEWHAT  
SLOWER EJECTION INTO THE CENTRAL/EASTERN STATES. CONFIDENCE IS  
ONLY MODERATE AT BEST THOUGH. SOME 00Z GEFS MEMBERS WERE ACTUALLY  
QUITE SLOW FOR THE SYSTEM HEADING INTO THE CENTRAL/EASTERN STATES  
BY LATE PERIOD BUT THE 06Z GEFS HAS TRENDED FASTER TOWARD (BUT NOT  
QUITE TO) THE ECMWF MEAN. ALSO, THERE HAS BEEN A NOTABLE TREND IN  
MOST GUIDANCE TOWARD FASTER ARRIVAL OF UPSTREAM PACIFIC ENERGY  
INTO THE NORTHWEST BY AROUND DAY 6 SUN AND THE OVERALL PATTERN  
SUGGESTS THE POTENTIAL FOR FASTER PROGRESSION OVER THE EAST BY  
EARLY NEXT WEEK. THE TREND FOR UPSTREAM FLOW IS FAIRLY RECENT SO  
WOULD LIKE TO WAIT AT LEAST ANOTHER CYCLE BEFORE MAKING ANY  
SIGNIFICANT ADJUSTMENTS. THERE IS REASONABLE AGREEMENT FOR THE  
STRONG STORM TRACKING FROM THE PLAINS THROUGH THE GREAT LAKES LATE  
THIS WEEK. BASED ON FORECAST CONSIDERATIONS THE BLEND STARTED  
WITH AN OPERATIONAL MODEL CONSENSUS ON DAY 3 THU, THEN REPLACED  
06Z GFS INPUT WITH THE 06Z GEFS MEAN COMPLETELY BY DAY 5 SAT,  
FOLLOWED BY A FOCUS PRIMARILY ON THE 00Z ECMWF-ECMWF MEAN/06Z GEFS  
MEAN ON DAYS 6-7 SUN-MON.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
CONSENSUS STILL DISPLAYS A HIGH POTENTIAL FOR SIGNIFICANT SNOWFALL  
AND STRONG WINDS--LEADING TO A PERIOD OF BLOWING SNOW AND POSSIBLE  
BLIZZARD CONDITIONS--FROM THE NORTH-CENTRAL PLAINS INTO THE UPPER  
GREAT LAKES DURING THE LATTER HALF OF THE WEEK. SOME STRONG TO  
SEVERE CONVECTION WILL BE POSSIBLE FARTHER SOUTH/SOUTHEAST IN THE  
WARM SECTOR. THE LATE WEEK/EARLY WEEKEND SYSTEM DIGGING INTO THE  
WEST WILL SPREAD RAIN AND HIGH ELEVATION SNOW ACROSS THE REGION.  
THE GREATEST UNCERTAINTY WILL BE THE EXTENT AND INTENSITY OF  
PRECIPITATION OVER/NEAR ARIZONA, DUE TO SENSITIVITY TO EXACT  
AMPLITUDE AND TIMING OF THE UPPER TROUGH. EJECTION OF THIS SYSTEM  
WILL LEAD TO A HEAVY RAINFALL THREAT FROM EASTERN TEXAS AND THE  
LOWER MISSISSIPPI VALLEY REGION INTO PARTS OF THE MID-ATLANTIC AND  
SOUTHERN NEW ENGLAND, AND POSSIBLY INCLUDING THE OHIO VALLEY. THE  
SOUTHWESTERN PART OF THIS BROAD AREA HAS THE HIGHER CONFIDENCE DUE  
TO A PERIOD OF MOIST LOW LEVEL GULF INFLOW INTERSECTING A FRONT  
STALLED OVER THE GULF COAST (ORIGINALLY TRAILING FROM THE LATE  
WEEK PLAINS STORM). THE PACIFIC NORTHWEST MAY SEE ADDITIONAL  
PRECIPITATION AFTER THE LATE WEEK SYSTEM IN ASSOCIATION WITH  
FRONTAL SYSTEMS PUSHED ALONG BY PROGRESSIVE FLOW ALOFT. THE MOST  
EXTREME TEMPERATURE ANOMALIES WILL BE OF THE COLD VARIETY OVER THE  
ROCKIES/PLAINS THU-SAT, BEHIND THE INITIAL PLAINS-GREAT LAKES  
STORM AND THEN IN EASTERLY UPSLOPE FLOW AHEAD OF THE NEXT SYSTEM  
EJECTING OUT OF THE WEST. SOME HIGHS MAY BE 20-30F BELOW NORMAL  
FOR ONE OR MORE DAYS. ALSO DURING THU-SAT EXPECT ABOVE NORMAL  
TEMPERATURES OVER THE EAST, ESPECIALLY FOR MORNING LOWS WHICH MAY  
BE 10-20F ABOVE NORMAL AT SOME LOCATIONS. EXPECT READINGS TO  
MODERATE OVER MUCH OF THE LOWER 48 BY NEXT MON.  
 
RAUSCH  
 
ADDITIONAL 3-7 DAY HAZARDS INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE 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  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page