114  
FXUS02 KWBC 270702  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT WED APR 27 2022  
 
VALID 12Z SAT APR 30 2022 - 12Z WED MAY 04 2022  
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD BEGINS SATURDAY WITH A CLOSED UPPER LOW  
OVER THE CENTRAL/NORTHERN PLAINS ALONG WITH A MODESTLY DEEP  
SURFACE LOW, AND THESE FEATURES WILL SLOWLY LIFT NORTHEAST INTO  
EARLY NEXT WEEK. THIS WILL SPREAD RAIN ACROSS MUCH OF THE CENTRAL  
U.S. WITH SOME CHANCE OF WINTRY WEATHER SPREADING INTO THE  
NORTHERN HIGH PLAINS ON THE BACKSIDE OF THE LOW. MUCH OF THE  
CENTRAL AND EASTERN U.S. CAN EXPECT PERIODIC SHOWERS AND  
THUNDERSTORMS THROUGH THE FIRST HALF OF NEXT WEEK AS FRONTS  
LINGER. ADDITIONALLY, PERIODIC UNSETTLED WEATHER IS FORECAST IN  
THE NORTHWEST AS A SERIES OF UPPER TROUGHS AND FRONTAL SYSTEMS  
MOVE THROUGH.  
 
   
..MODEL GUIDANCE EVALUATION
 
 
RECENT MODEL GUIDANCE IS REASONABLY AGREEABLE AS THE MEDIUM RANGE  
FORECAST BEGINS IN TERMS OF THE CENTRAL U.S. UPPER-LEVEL AND  
SURFACE LOWS THOUGH WITH SOME SLIGHT SPREAD IN EXACT PLACEMENT, AS  
WELL AS AN UPPER LOW SLOWLY PULLING AWAY FROM THE CANADIAN  
MARITIMES. THERE IS GOOD CONSENSUS FOR THESE FEATURES TO TRACK  
EAST-NORTHEASTWARD WITH A GENERAL WEAKENING TREND FOR THE CENTRAL  
U.S. LOWS THROUGH SUNDAY-MONDAY. THERE IS SOMEWHAT MORE  
VARIABILITY WITH UPSTREAM ENERGY COMING INTO THE PACIFIC NORTHWEST  
SATURDAY AND ITS EVOLUTION GOING FORWARD. GFS RUNS HAVE BEEN A BIT  
WEAKER WITH THE SHORTWAVE INITIALLY BUT HOLD ONTO IT PERHAPS  
LONGER BEFORE GETTING ABSORBED IN THE EAST-CENTRAL U.S. AROUND  
MONDAY-TUESDAY. THE EARLY PART OF THE WPC FORECAST FEATURED A  
BLEND OF THE DETERMINISTIC GUIDANCE BEFORE GRADUALLY PHASING OUT  
SOME UKMET AND CMC INFLUENCE IN FAVOR OF THE ECMWF ENSEMBLE MEAN.  
 
ANOTHER ROUND OF UPPER ENERGY SHOULD SPILL INTO THE WEST FOR THE  
EARLY PART OF THE WORKWEEK, LIKELY CLOSING OFF ANOTHER UPPER LOW  
AS IT TRACKS THROUGH THE WESTERN AND CENTRAL CONUS. THE 12Z GFS  
WAS THE FASTEST/FARTHEST EAST WITH THIS FEATURE, WITH THE 18Z AND  
NEWER 00Z GFS AND THE REST OF THE DETERMINISTIC GUIDANCE SLOWER.  
HOWEVER, CMC RUNS HAVE PERHAPS BEEN TOO SLOW WITH THE UPPER LOW'S  
MOVEMENT, WITH EVEN ITS 12Z ENSEMBLE MEAN FASTER. THE ECMWF AND EC  
ENSEMBLE MEAN SEEMED LIKE A GOOD MIDDLE GROUND BETWEEN THESE  
SLOWER AND FASTER ENDS OF THE SPECTRUM, SO FAVORED THOSE FOR THE  
WPC FORECAST BLEND BY THE LATTER PART OF THE PERIOD, WITH SOME  
INCLUSION OF THE 18Z GFS AND GEFS MEAN.  
 
   
..SENSIBLE WEATHER/THREATS
 
 
THE FIRST SURFACE LOW PRESSURE SYSTEM AFFECTING THE LOWER 48 OVER  
THE WEEKEND WILL SPREAD PRECIPITATION ACROSS MUCH OF THE CENTRAL  
AND EASTERN U.S., WITH SOME WINTRY WEATHER POSSIBLE IN THE  
DAKOTAS, WITH THE BEST CHANCES IN THE HIGHER ELEVATIONS OF THE  
BLACK HILLS. IN PORTIONS OF THE DAKOTAS, PRECIPITATION MAY BEGIN  
AS RAIN AND TRANSITION TO MIXED PRECIPITATION OR SNOW, THOUGH  
DETAILS OF THESE THREATS REMAIN SOMEWHAT UNCERTAIN. ADDITIONALLY,  
RAIN COULD BECOME HEAVY TO LOCALLY EXCESSIVE FROM PARTS OF THE  
PLAINS INTO THE MISSISSIPPI/OHIO VALLEYS ON SATURDAY. THEN AS THE  
LOW PRESSURE SYSTEM SHIFTS EASTWARD EARLY NEXT WEEK, PRECIPITATION  
CHANCES ARE EXPECTED TO SPREAD EASTWARD, BUT LINGER IN THE CENTRAL  
U.S. AS WELL AS THE FRONT THERE MAY STALL. CURRENT FORECASTS SHOW  
POTENTIAL FOR HEAVY RAINFALL ON SUNDAY ACROSS THE SOUTHERN PLAINS,  
THOUGH THE AXIS OF HEAVIEST RAINFALL MAY SHIFT IN FUTURE  
FORECASTS. SCATTERED SHOWERS AND THUNDERSTORMS WILL LIKELY PERSIST  
FROM THE PLAINS EASTWARD THROUGH THE FIRST HALF OF NEXT WEEK.  
FURTHERMORE, ROUNDS OF LIGHT TO MODERATE PRECIPITATION (SNOW IN  
THE HIGHER ELEVATIONS AND RAIN IN THE LOWER ELEVATIONS) ARE  
FORECAST ACROSS THE NORTHWEST AS A SERIES OF FRONTS CROSS THE  
REGION ALONG WITH UPPER-LEVEL ENERGY. ONE SUCH FRONT AND LOW  
PRESSURE SYSTEM COULD EJECT INTO THE CENTRAL U.S. AROUND MIDWEEK.  
 
TEMPERATURE-WISE, THE GENERAL TREND OVER THE LOWER 48 WILL BE FOR  
COOLER THAN AVERAGE WEATHER IN THE NORTHERN TIER AND COOLER THAN  
AVERAGE IN THE SOUTHERN TIER. THE CORE OF THE COLDEST AIR SHOULD  
BE ACROSS THE NORTHERN HIGH PLAINS TO MIDWEST, WHERE HIGHS WILL BE  
AROUND 15-25F UNDERNEATH PERIODIC UPPER TROUGHING. MEANWHILE,  
SLIGHTLY ABOVE NORMAL TEMPERATURES SHOULD STRETCH ACROSS MUCH OF  
THE SOUTHERN TIER, AND INTO THE OHIO/TENNESSEE VALLEYS AS WELL,  
PARTICULARLY IN TERMS OF WARMER THAN NORMAL LOWS.  
 
TATE  
 
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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