601  
FXUS02 KWBC 290701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT FRI APR 29 2022  
 
VALID 12Z MON MAY 02 2022 - 12Z FRI MAY 06 2022  
   
..OVERVIEW
 
 
EXPECT AN ACTIVE WEATHER PATTERN NEXT WEEK WITH A SERIES OF  
PACIFIC SYSTEMS (EACH SUPPORTED BY AN UPPER TROUGH THAT MAY  
CONTAIN A CLOSED LOW FOR A PERIOD OF TIME) ENTERING AND  
PROGRESSING ACROSS THE LOWER 48. THESE SYSTEMS WILL SPREAD RAIN  
AND HIGH ELEVATION SNOW ACROSS THE PACIFIC NORTHWEST AND  
NORTH-CENTRAL ROCKIES/HIGH PLAINS, AND THEN MOSTLY RAIN OVER A  
LARGE PART OF THE CENTRAL/EASTERN U.S. SOME AREAS OF PRECIPITATION  
MAY BE HEAVY AND SPC INDICATES A THREAT OF SEVERE WEATHER OVER THE  
SOUTHERN PLAINS AND VICINITY MONDAY INTO TUESDAY. WPC HAS ALSO  
ISSUED AN EXPERIMENTAL MEDIUM RANGE "SLIGHT" RISK FOR EXCESSIVE  
RAINFALL THEN FROM THE EASTERN SOUTHERN PLAINS INTO THE  
MID-MISSISSIPPI VALLEY. UPSTREAM THIS PATTERN WILL LIKELY LEAVE  
THE SOUTHERN HALF OR THIRD OF THE WEST, THE NORTHERN PLAINS NEAR  
THE CANADIAN BORDER, AND THE GULF COAST AS THE RELATIVELY DRIER  
AREAS DURING THE FORECAST PERIOD. AS FOR INDIVIDUAL FEATURES, A  
LEADING SYSTEM WILL WEAKEN AS IT TRACKS NORTHEAST FROM THE UPPER  
MISSISSIPPI VALLEY SUNDAY ONWARD WHILE ANOTHER OVER THE WEST BY  
EARLY SUNDAY SHOULD REACH THE MIDWEST/GREAT LAKES BY TUESDAY AND  
THE NEXT ONE ENTERING THE WEST BY MONDAY MAY REACH AS FAR EAST AS  
THE MISSISSIPPI VALLEY BY NEXT THURSDAY. A LARGER SCALE UPPER  
TROUGH APPROACHING THE WEST COAST NEXT THURSDAY MAY ALSO BRING  
SOME MOISTURE INTO THE NORTHWEST.  
 
   
..MODEL GUIDANCE EVALUATION
 
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM BEST  
CLUSTERED GUIDANCE FROM THE 18 UTC GFS AND 12 UTC ECMWF ALONG WITH  
A COMPATIBLE 01 UTC NATIONAL BLEND OF MODELS (NBM) DAYS 3-5  
(MONDAY INTO WEDNESDAY). THIS SOLUTION MAINTAINS GOOD WPC  
CONTINUITY AND HAS STRONG ENSEMBLE SUPPORT IN A PATTERN WITH  
SEEMINGLY ABOVE NORMAL FORECAST PREDICTABILITY. INCREASING  
FORECAST SPREAD, PARTICULARLY WITH EMBEDDED SYSTEM PROGRESSION  
VARIANCE, PORTENDS NEAR AVERAGE PREDICTABILITY INTO DAYS 6/7  
(THURSDAY/NEXT FRIDAY). OPTED TO EMBRACE A TRANSITION TO A  
COMPOSITE BLEND OF THE STILL COMPATIBLE 18 UTC GEFS MEAN AND THE  
12 UTC ECMWF ENSEMBLE MEAN ALONG WITH THE 01 UTC NBM THAT SEEM TO  
OFFER A REASONABLE FLOW EVOLUTION INTO THESE LONGER TIME FRAMES.  
LATEST 00 UTC GUIDANCE REMAINS IN LINE.  
 
   
..SENSIBLE WEATHER/THREATS
 
 
OVER THE WEST, YET ANOTHER SYSTEM WILL SPREAD MOISTURE FROM THE  
PACIFIC NORTHWEST THROUGH THE ROCKIES INTO EARLY TO MID NEXT WEEK.  
DEPENDING ON EXACT SYSTEM DETAILS, THIS COULD PRODUCE SOME  
ENHANCED TOTALS, INCLUDING ACCUMULATING SNOWS INTO THE  
NORTH-CENTRAL ROCKIES AND ADJACENT HIGH PLAINS. SUBSEQUENTLY, AN  
AMPLIFIED UPPER TROUGH AND SURFACE FRONTAL SYSTEM STILL EXPECTED  
TO BREACH THE WEST COAST THURSDAY INTO NEXT FRIDAY SHOULD BRING A  
RENEWED PRECIPITATION FOCUS INTO THE PACIFIC NORTHWEST AND  
INCREASINGLY INLAND.  
 
OVER THE CENTRAL/EASTERN U.S., THE LEADING SURFACE LOW TRACKING  
OUT OF THE GREAT LAKES ON MONDAY AND ASSOCIATED FRONTS WILL SPREAD  
PRECIPITATION ACROSS MUCH OF THE EASTERN U.S. WITH GENERALLY LIGHT  
TO MODERATE RAIN. POTENTIAL EXISTS FOR POCKETS OF LOCALLY HEAVIER  
ACTIVITY THOUGH. THE TRAILING COLD FRONT WILL TEND TO STALL OVER  
THE SOUTHERN PLAINS WHILE THE NEXT SYSTEM EMERGES FROM THE WEST,  
WITH THIS SYSTEM CURRENTLY EXPECTED TO TRACK THROUGH THE  
PLAINS/MIDWEST EARLY NEXT WEEK. CURRENTLY THERE REMAINS DECENT  
POTENTIAL FOR AREAS OF MODERATE TO HEAVY RAINFALL FROM PORTIONS  
OF THE CENTRAL/SOUTHERN PLAINS NORTHEASTWARD TO INCLUDE A FOCUS  
FOR A "SLIGHT" RISK OF EXCESSIVE RAINFALL INTO MONDAY/TUESDAY OVER  
THE SOUTH-CENTRAL U.S. SOME SEVERE WEATHER IS ALSO POSSIBLE, WITH  
THE STORM PREDICTION CENTER CURRENTLY INDICATING THE BEST  
POTENTIAL FOR SEVERE THUNDERSTORMS ACROSS THE SOUTHERN PLAINS  
SUNDAY AND MONDAY. THE GUIDANCE SIGNAL IS ALSO GROWING THAT THE  
NEXT SYSTEM IN THE SERIES OUT FROM THE WEST MAY PRODUCE YET  
ANOTHER AREA OF SIGNIFICANT RAINFALL OVER AND OUT FROM THE CENTRAL  
U.S. AGAIN MID-LATE NEXT WEEK. CONFIDENCE IS FAIRLY LOW FOR  
DETAILS OF COVERAGE AND TIMING. A SYSTEM ON THE DEEPEST SIDE OF  
THE SPREAD COULD PRODUCE SOME SNOW IN THE NORTHERN PERIPHERY, BUT  
THIS HAS FAIRLY LOW PROBABILITY AT THE MOMENT. SOME AREAS OVER  
THE CENTRAL U.S. NEED TO MONITOR FORECASTS OF THESE SYSTEMS GIVEN  
THE POTENTIAL TO PRODUCE SIGNIFICANT WEATHER AND SENSITIVITY TO  
ADDITIONAL RAINFALL. AT LEAST FOR THE TIME BEING, THE MAJORITY OF  
FORECASTS PRODUCE MOST PRECIPITATION TO THE SOUTH OF THE FAR  
NORTHERN PLAINS WHERE SOIL CONDITIONS ARE THE WETTEST.  
 
SCHICHTEL  
 
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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