868  
FXUS02 KWBC 082050  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
450 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  
 
HAZARDS:  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST,  
THU, APR 11.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND  
THE NORTHERN GREAT BASIN, SAT-MON, APR 13-APR 15.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL ROCKIES AND  
THE CENTRAL GREAT BASIN, FRI-SAT, APR 12-APR 13.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL PLAINS, THE  
MIDDLE MISSISSIPPI VALLEY, THE GREAT LAKES, THE UPPER MISSISSIPPI  
VALLEY, AND THE NORTHERN PLAINS, THU-FRI, APR 11-APR 12.  
- HEAVY RAIN ACROSS PORTIONS OF THE MID-ATLANTIC, THE LOWER  
MISSISSIPPI VALLEY, THE CENTRAL APPALACHIANS, THE TENNESSEE  
VALLEY, THE GREAT LAKES, THE MIDDLE MISSISSIPPI VALLEY, THE  
NORTHEAST, THE SOUTHERN APPALACHIANS, THE SOUTHEAST, THE SOUTHERN  
PLAINS, AND THE OHIO VALLEY, SAT-SUN, APR 13-APR 14.  
- HEAVY RAIN ACROSS PORTIONS OF THE GREAT LAKES AND THE OHIO  
VALLEY, FRI, APR 12.  
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES, SUN-MON, APR  
14-APR 15.  
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL PLAINS, THE GREAT  
LAKES, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS,  
THU-FRI, APR 11-APR 12.  
- SEVERE WEATHER ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY,  
THE LOWER MISSISSIPPI VALLEY, THE GREAT LAKES, THE OHIO VALLEY,  
AND THE TENNESSEE VALLEY, THU, APR 11.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE LOWER MISSISSIPPI  
VALLEY, THE GREAT LAKES, THE UPPER MISSISSIPPI VALLEY, AND THE  
NORTHERN PLAINS.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER  
MISSISSIPPI VALLEY, THE NORTHERN PLAINS, THE TENNESSEE VALLEY, THE  
NORTHERN ROCKIES, THE MIDDLE MISSISSIPPI VALLEY, THE NORTHERN  
GREAT BASIN, THE UPPER MISSISSIPPI VALLEY, THE PACIFIC NORTHWEST,  
AND THE OHIO VALLEY.  
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN PLAINS, THE  
TENNESSEE VALLEY, THE PACIFIC NORTHWEST, THE NORTHERN GREAT BASIN,  
THE UPPER MISSISSIPPI VALLEY, AND THE SOUTHERN PLAINS.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL  
ROCKIES, THE LOWER MISSISSIPPI VALLEY, THE NORTHERN PLAINS, THE  
SOUTHERN ROCKIES, THE MIDDLE MISSISSIPPI VALLEY, THE UPPER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE SOUTHWEST, THU,  
APR 11.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE CENTRAL ROCKIES, THE NORTHERN PLAINS, THE SOUTHERN  
ROCKIES, THE UPPER MISSISSIPPI VALLEY, AND THE SOUTHERN PLAINS,  
THU-SAT, APR 11-APR 13.  
- ENHANCED WILDFIRE RISK ACROSS PORTIONS OF THE THE SOUTHERN  
PLAINS AND THE SOUTHWEST, THU, APR 11.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF MAINLAND ALASKA AND THE  
ALEUTIANS, THU, APR 11.  
- HIGH WINDS ACROSS PORTIONS OF MAINLAND ALASKA AND THE ALEUTIANS,  
THU, APR 11.  
 
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  
 

 
 
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