472  
FXUS02 KWBC 121922  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
321 PM EDT FRI APR 12 2019  
 
VALID 12Z MON APR 15 2019 - 12Z FRI APR 19 2019  
 
...ANOTHER MAJOR SPRING STORM NEXT WEEK TO BRING RISK OF HEAVY  
RAINFALL/FLOODING FROM THE MID-LOWER MISSISSIPPI VALLEY/OHIO  
VALLEY ALONG SOME RISK OF LEAD SEVERE WEATHER SOUTH AND WRAPBACK  
SNOWS NORTH...  
 
   
..GUIDANCE PREFERENCES AND PREDICTABILITY ASSESSMENT
 
 
A DEEP LEAD SHORT RANGE SYSTEM WILL EXIT THROUGH NEW ENGLAND  
MONDAY AS OUR WEATHER EMPHASIS RETURNS TO THE WEST. MODELS AND  
ENSEMBLES OVERALL CLUSTER REASONABLY WELL MONDAY INTO WEDNESDAY  
AND A PREFERRED COMPOSITE BLEND CONTINUES MAINTAINS GOOD WPC  
CONTINUITY IN SHOWCASING THE TRACK OF A SERIES OF DYNAMIC  
MID-UPPER LEVEL SHORTWAVE TROUGHS/HEIGHT FALLS AND ASSOCIATED  
SWATHS OF ENHANCED BUT PROGRESSIVE PRECIPITATION FROM THE EASTERN  
PACIFIC INLAND ACROSS THE WEST/ROCKIES WITH A SUBSTANTIAL HEAVY  
MOUNTAIN SNOW THREAT. ENERGIES THEN EMERGE WITHIN ANOTHER PATTERN  
FAVORABLE FOR MAJOR STORM GENESIS OVER THE PLAINS INTO MIDWEEK.  
 
MODELS AND ENSEMBLES HAVE NOT BEEN AS ALIGNED WITH RECENT RUNS  
WITH SUBSEQUENT STORM TIMING/DETAILS INTO LATER NEXT WEEK, BUT THE  
OVERALL SIGNAL FOR SIGNIFICANT STORM GENESIS REMAINS QUITE STRONG.  
THE LATEST GFS AND ECMWF DETERMINISTIC RUNS TRENDED FASTER  
OVERNIGHT, BUT HAVE NOW RETREATED BACK SLOWER TO OFFER BETTER  
CONTINUITY WITH YESTERDAYS WPC FORECAST AGAIN. THIS IS ALBEIT WITH  
A SHIFT A BIT MORE NORTHWESTAWARD THAT COULD PORTEND A BETTER  
OPPORTUNITY FOR WINTERY PRECIPITATION OVER A MARGINALLY COOLDED  
UPPER MIDWEST/GREAT LAKES INTO NEXT FRIDAY CONSIDERING MOST  
SOLUTIONS DO STILL WRAP UP QUITE A DEEP SURFACE LOW/FRONTAL SYSTEM  
AND COOLING NORTHERN STREAM FRONTAL DRAPE OVERTOP. INTERESTINGLY,  
THE GEFS INDIVIDUAL ENSEMBLE MEMBERS UNCHARACTERISTICALLY CLUSTER  
SLOWER THAN THE GFS/ECMWF WHILE ECMWF ENSEMBLE MEMBERS  
UNCHARACTERISTICALLY CLUSTER MORE PROGRESSIVE THAN THE GFS/ECMWF.  
OVERALL, WPC HAS TRENDED BACK SLOWER VERSUS OUR OVERNIGHT  
CONTINUITY MOST NOW IN LINE WITH THE DETERMINISTIC GFS/ECMWF INTO  
THURSDAY AND NEXT FRIDAY.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
SIGNIFICANT PRECIPITATION WILL AGAIN INCREASE BY WEDNESDAY INTO  
THURSDAY ACROSS THE MISSISSIPPI/MISSOURI VALLEYS INTO THE GREAT  
LAKES AS LOW PRESSURE STRENGTHENS OVER OKLAHOMA/KANSAS. MULTI-INCH  
RAINFALL TOTALS ARE PROBABLE (ENHANCED IN EMBEDDED CONVECTION) IN  
SOME LOCATIONS OF THE WARM SECTOR AND PERHAPS TO THE  
NORTH/NORTHEAST OF THE LOW WITH ADDITIONAL NORTHERN STREAM  
SUPPORT. TEMPERATURES TO THE NORTH/NORTHWEST OF THE LOW MAY ONLY  
BE MARGINALLY COLD ENOUGH FOR SNOW DEPENDING ON THE AMOUNT OF  
COOLER AIR BEHIND A CANADIAN COLD FRONT. TEMPERATURES WILL LARGELY  
BE WITHIN 10 DEGREES OF AVERAGE VALUES FOR MID-APRIL BUT WITH A  
SLOWER MODERATION OVER PARTS OF THE DAKOTAS/MINNESOTA OWING TO THE  
MELTING OF NEAR-TERM SNOW COVER.  
 
SCHICHTEL  
 
HAZARDS:  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHEAST, THE  
CENTRAL GREAT BASIN, THE NORTHERN  
PLAINS, THE NORTHERN ROCKIES, THE CENTRAL ROCKIES, THE NORTHERN  
GREAT BASIN, AND THE PACIFIC  
NORTHWEST, MON-TUE, APR 15-APR 16.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL GREAT BASIN,  
CALIFORNIA, AND THE SOUTHWEST,  
TUE, APR 16.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL ROCKIES AND  
THE CENTRAL PLAINS, WED-THU, APR  
17-APR 18.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE GREAT LAKES AND THE  
UPPER MISSISSIPPI VALLEY, THU, APR  
18.  
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE  
TENNESSEE VALLEY, THE GREAT  
LAKES, THE MIDDLE MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI  
VALLEY, AND THE OHIO VALLEY, WED-THU,  
APR 17-APR 18.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE GREAT LAKES, THE  
SOUTHERN PLAINS, THE UPPER MISSISSIPPI  
VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER  
MISSISSIPPI VALLEY, THE NORTHERN  
PLAINS, THE NORTHERN GREAT BASIN, THE MIDDLE MISSISSIPPI VALLEY,  
THE UPPER MISSISSIPPI VALLEY, THE  
PACIFIC NORTHWEST, AND THE OHIO VALLEY.  
- FLOODING LIKELY ACROSS PORTIONS OF THE PACIFIC NORTHWEST, THE  
UPPER MISSISSIPPI VALLEY, AND THE  
NORTHERN PLAINS.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE GREAT LAKES,  
THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS, THU-FRI,  
APR 18-APR 19.  
 
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  
 

 
 
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