262  
FXUS02 KWBC 121601  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1201 PM EDT FRI APR 12 2019  
 
VALID 12Z MON APR 15 2019 - 12Z FRI APR 19 2019  
 
...A THREAT FOR ANOTHER MAJOR SPRING STORM WITH A RISK HEAVY  
RAINFALL/FLOODING FROM THE MID-LOWER MISSISSIPPI VALLEY TO THE  
OHIO VALLEY STARTING MIDWEEK ALONG SOME LEAD RISK OF SEVERE  
WEATHER...  
 
   
..GUIDANCE PREFERENCES AND PREDICTABILITY ASSESSMENT
 
 
A DEEP LEAD SYSTEM OUT OF THE SHORT RANGE 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, EMERGING WITH YET 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
 
 
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 (AND PERHAPS ONLY AT NIGHT) DEPENDING ON THE AMOUNT OF  
COOLER AIR BEHIND A WEAKENING CANADIAN COLD FRONT WEDNESDAY.  
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 NEAR-TERM SNOW COVER THAT WILL TAKE  
AT LEAST SEVERAL DAYS TO MELT.  
 
SCHICHTEL  
 
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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