783  
FXUS02 KWBC 311858  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
256 PM EDT THU MAR 31 2022  
 
VALID 12Z SUN APR 3 2022 - 12Z THU APR 7 2022  
 
...HEAVY RAINFALL/CONVECTION AND RUNOFF THREAT TO FOCUS ACROSS THE  
SOUTH NEXT WEEK...  
...PACIFIC NORTHWEST HEAVY RAINS AND TERRAIN/MOUNTAIN HEAVY SNOW  
THREAT INLAND TO THE NORTHERN ROCKIES...  
 
19Z UPDATE: THE 12Z MODEL GUIDANCE SUITE IS IN VERY GOOD  
AGREEMENT ON THE QUASI-ZONAL FLOW PATTERN ACROSS THE CONTINENTAL  
U.S. FOR THE SUNDAY-MONDAY TIME PERIOD, ALTHOUGH THE ECMWF IS  
SLIGHTLY MORE AMPLIFIED WITH THE UPPER TROUGH OVER THE MIDWEST ON  
MONDAY AND THE CMC A BIT STRONGER WITH THE SHORTWAVE EXITING NEW  
ENGLAND. BY TUESDAY AND THROUGH MIDWEEK, THE GFS AND TO A LESSER  
EXTENT ITS ENSEMBLE MEAN, ARE MORE PROGRESSIVE WITH THE SOUTHERN  
STREAM SHORTWAVE CROSSING THE GULF COAST REGION, WITH A GFS/ECMWF  
COMPROMISE SUFFICING AS A STARTING POINT HERE WITH SOME ADDITIONAL  
WEIGHTING FROM THE ECENS MEAN. BY THE END OF THE FORECAST PERIOD  
NEXT THURSDAY, THE GFS/GEFS IS ALSO MORE PROGRESSIVE WITH THE MAIN  
CLOSED LOW OVER THE GREAT LAKES REGION, WITH THE ECENS SERVING AS  
AN EXCELLENT MIDDLE GROUND SOLUTION. IN TERMS OF THE QPF  
FORECAST, THE AXIS OF HEAVIEST RAINFALL IS SLIGHTLY FARTHER SOUTH  
ACROSS THE GULF COAST STATES COMPARED TO CONTINUITY, WITH AERIAL  
AVERAGES ON THE ORDER OF 1 TO 3 INCHES LIKELY FROM LOUISIANA TO  
GEORGIA. THE PREVIOUS FORECAST DISCUSSION FOLLOWS BELOW. /HAMRICK  
-----------------  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED FROM A BLEND  
OF WELL CLUSTERED GUIDANCE FROM THE 18 UTC GFS/GEFS MEAN, THE 12  
UTC ECMWF/UKMET/CANADIAN/ECMWF ENSEMBLE MEAN AND THE 01 UTC  
NATIONAL BLEND OF MODELS ALONG WITH WPC CONTINUITY DAYS 3-7  
(SUN-NEXT THU). EMBEDDED SMALLER SCALE SYSTEM DIFFERENCES AND RUN  
TO RUN CONTINUITY VARIANCES HAVE BECOME LESS PROBLEMATIC WITH THE  
18 UTC GFS/GEFS TRENDING MORE IN LINE THAN EARLIER RUNS,  
ESPECIALLY INTO LATER PERIOD OVER THE PACIFIC/NORTHWEST. NEWER 00  
UTC GUIDANCE REMAINS IN CLOSE ALIGNMENT. OVERALL, THIS SEEMS TO  
BOLSTER MEDIUM RANGE FORECAST CONFIDENCE TO ABOVE NORMAL LEVELS,  
ALBEIT WITH THE CAVEAT THAT THE ENERGETIC MULTI-SYSTEM PATTERN IS  
ALSO TRANSITIONING TO HIGHER AMPLITUDE/CONVECTIVE POTENTIAL OVER  
TIME THAT WILL LIKELY VARY THE LOCAL THREAT FOCUS.  
   
..OVERVIEW AND WEATHER HIGHLIGHTS/THREATS
 
 
HIGHLY ENERGETIC PACIFIC FLOW WILL WORK INCREASINGLY INLAND FROM  
THE NORTHWEST TO THE ROCKIES INTO EARLY NEXT WEEK. THIS WILL ACT  
TO TRANSPORT SOME DEEPER MOISTURE IN SUPPORT OF AN EMERGING HEAVY  
PRECIPITATION FOCUS WITH RAINFALL OVER COASTAL AND FAVORED TERRAIN  
OF THE PACIFIC NORTHWEST. THE PATTERN ALSO FAVORS PERIODS WITH  
TERRAIN/MOUNTAIN HEAVY SNOWS FROM THE NORTHWEST TO THE NORTHERN  
INTERMOUNTAIN WEST/ROCKIES PRIOR TO AMPLIFIED UPPER RIDGE BUILDING  
SLATED TO BUILD EASTWARD OVER THE WEST STARTING MIDWEEK.  
 
DOWNSTREAM PROGRESSION AND SYSTEMS OUT FROM THE WEST AND  
INCREASING NORTHERN STREAM PHASING POTENTIAL OVER TIME WILL  
COMBINE TO SUPPORT CYCLOGENESIS/FRONTOGENESIS OVER THE CENTRAL AND  
EASTERN STATES NEXT WEEK. THERE IS A GROWING GUIDANCE SIGNAL FOR  
DEVELOPMENT OF A BUILDING AREA OF ENHANCED RAINFALL AND SOME  
THREAT TO MONITOR FOR SOME SEVERE CONVECTION ACROSS THE  
EAST-CENTRAL U.S. (BOTH ESPECIALLY ACROSS A MORE  
UNSTABLE/CONVECTIVE SOUTH) EARLY-MID NEXT WEEK AS DEEPER GULF  
MOISTURE RETURNS AND INTERACTS WITH THE COMPLEX SERIES OF WAVY  
FRONTS AND A STALLED LEAD FRONT. ACCORDINGLY AND CONSIDERING  
ANTECEDENT RAINFALL, WPC SHOWS A "SLIGHT" RISK ON THE NEWLY  
EXPERIMENTAL MEDIUM RANGE EXCESSIVE RAINFALL OUTLOOK INTO DAY 5  
(ERO LINKED BELOW). GUIDANCE CONSENSUS HAS IMPROVED AT LONGER TIME  
FRAMES WITH A WELL DEVELOPED CLOSED UPPER LOW FORMING OVER THE  
NORTH-CENTRAL U.S. BY MIDWEEK AS THE PATTERN BECOMES AMPLIFIED  
DOWNSTREAM OF THE AFOREMENTIONED BUILDING UPPER RIDGE OVER THE  
WEST. THERE IS SOME POTENTIAL THEN FOR SOME WRAPPING/OVERRUNNING  
APRIL SNOWS FROM THE UPPER GREAT LAKES TO THE NORTHERN TIER OF THE  
NORTHEAST.  
 
HAMRICK/SCHICHTEL  
 
HAZARDS:  
 
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND  
THE NORTHERN GREAT BASIN,  
SUN-MON, APR 3-APR 4.  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER  
MISSISSIPPI VALLEY, THE TENNESSEE  
VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE MID-ATLANTIC, THE  
SOUTHERN APPALACHIANS, THE SOUTHEAST,  
AND THE SOUTHERN PLAINS, MON-TUE, APR 4-APR 5.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE MID-ATLANTIC,  
AND THE SOUTHERN APPALACHIANS,  
TUE-WED, APR 5-APR 6.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI  
VALLEY, THE GREAT LAKES, THE UPPER  
MISSISSIPPI VALLEY, THE NORTHERN PLAINS, AND THE OHIO VALLEY.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE UPPER  
MISSISSIPPI VALLEY AND THE NORTHERN  
PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL  
GREAT BASIN, THE NORTHERN PLAINS,  
THE NORTHERN ROCKIES, THE CENTRAL ROCKIES, THE NORTHERN GREAT  
BASIN, AND THE PACIFIC NORTHWEST,  
MON-WED, APR 4-APR 6.  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, 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/#PAGE=ERO  
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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