832  
FXUS02 KWBC 200615  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
214 AM EDT WED APR 20 2022  
 
VALID 12Z SAT APR 23 2022 - 12Z WED APR 27 2022  
 
...SIGNIFICANT LATE SEASON WINTER STORM INCREASINGLY LIKELY FOR  
NORTHERN PLAINS THIS WEEKEND AND POTENTIALLY HEAVY RAINFALL THREAT  
TO SOME AREAS FARTHER SOUTH...  
   
..WEATHER PATTERN OVERVIEW
 
 
A HIGHLY AMPLIFIED PATTERN IS EXPECTED OVER THE FORECAST PERIOD  
HIGHLIGHTED BY AN ANOMALOUS CLOSED UPPER LOW COMING OUT OF THE  
WEST INTO THE PLAINS THIS WEEKEND WHILE STRONG RIDGING ANCHORS  
OVER THE SOUTHEAST. A DEEPENING SURFACE LOW WILL TRACK FROM THE  
ROCKIES TOWARD THE UPPER MIDWEST BRINGING A WIDE VARIETY OF  
WEATHER HAZARDS - SIGNIFICANT SNOW AND WIND TO THE NORTHERN PLAINS  
AND EVENTUALLY A HEAVY RAIN THREAT EVOLVING LATE IN THE WEEKEND  
INTO EARLY NEXT WEEK OVER PORTIONS OF THE SOUTHERN PLAINS TO THE  
OZARKS. MEANWHILE, MUCH ABOVE NORMAL TEMPERATURES WILL BE FOUND  
DOWNSTREAM UNDERNEATH THE SOUTHEAST RIDGE AND FINALLY, ANOTHER  
PACIFIC UPPER TROUGH SHOULD APPROACH THE NORTHWESTERN U.S. BY THE  
BEGINNING OF NEXT WEEK.  
   
..MODEL GUIDANCE EVALUATION
 
 
A BLEND OF THE LATEST AVAILABLE DETERMINISTIC GUIDANCE WAS USED  
FOR THIS FORECAST CYCLE - MAINLY THE 12Z ECMWF, 18Z/12Z GFS, 12Z  
CMC, 12Z UKMET. FOR DAYS 3-4, A BLEND MOSTLY CONSISTING OF THE  
ECMWF/GFS WAS USED FOR THE STRONG LOW PRESSURE SYSTEM IN THE  
PLAINS WHERE THE DETERMINISTIC RUNS AND ENSEMBLE CLUSTERING  
CONTINUES TO IMPROVE SUCH THAT CONFIDENCE IS ABOVE NORMAL. FURTHER  
SOUTH ALONG THE TRAILING FRONTAL BOUNDARY SUNDAY INTO MONDAY -  
THERE REMAINS SOME TIMING AND SPEED ISSUES WITH HOW FAST THE FRONT  
KICKS SOUTHEAST. SOME SUGGESTION THAT THE FRONT WILL HANG OUT/SLOW  
ACROSS PORTIONS OF THE SOUTHERN PLAINS TO OZARKS BUT SOME FORECAST  
RUNS SHOW A MUCH MORE PROGRESSIVE SCENARIO THOUGH THE SETUP FAVORS  
A SLOW SOLUTION SO THE FORECAST BLENDED SOME OF THE SLOWER  
GUIDANCE. BY DAYS 6-7, FORECAST UNCERTAINTY GROWS SUBSTANTIALLY  
WITH HOW THE PHASING OR LACK OF SHORTWAVE ENERGY OVER THE  
NORTHEAST OCCURS AND ITS PROGRESSION POTENTIALLY BLOCKED BY  
RIDGING TO THE NORTHEAST. ANOTHER STORM SYSTEM IS LIKELY TO  
APPROACH THE PACIFIC NORTHWEST TOWARD THE END OF THE PERIOD.  
   
..SENSIBLE WEATHER/THREATS
 
 
A STRONG TO POTENTIALLY SIGNIFICANT STORM SYSTEM IS INCREASINGLY  
LIKELY TO EMERGE OUT OF THE ROCKIES AND TRACK TOWARD THE NORTHERN  
PLAINS AND UPPER MIDWEST LATER THIS WEEK INTO THE WEEKEND. THE  
BEST POTENTIAL FOR SIGNIFICANT TOTALS OF SNOW AND BLOWING SNOW ARE  
FAVORED FROM NORTHEAST WYOMING AND EASTERN MONTANA TO MUCH OF  
WESTERN/CENTRAL NORTH DAKOTA AND FAR NORTHWEST SOUTH DAKOTA -  
IMMEDIATELY WEST TO NORTHWEST OF THE SURFACE LOW TRACK. THE STRONG  
WINDS AND HEAVY SNOW COMBINED COULD LEAD TO NEAR BLIZZARD  
CONDITIONS FOR SOME AREAS IF MODEL TRENDS CONTINUE. WHILE THERE IS  
SOME UNCERTAINTY IN THE SPEED AND TRACK - THE GUIDANCE IS  
INCREASINGLY BECOMING CLUSTERED ON THE IDEA OF A HIGH IMPACT LATE  
SEASON WINTER STORM FOR PORTIONS OF THE REGION WHERE THE LATEST  
WINTER WEATHER OUTLOOK SHOWS HIGH PROBABILITIES FOR SEVERAL INCHES  
OF SNOW.  
 
AS THE LOW LIFTS NORTH OF THE GREAT LAKES, ITS ASSOCIATED FRONTAL  
BOUNDARY EXTENDING SOUTHWARD THROUGH THE CENTRAL U.S. IS LIKELY TO  
SLOW, STALL OR BECOME NEARLY STATIONARY LATE IN THE WEEKEND INTO  
EARLY NEXT WEEK ACROSS PORTIONS OF THE SOUTHERN/CENTRAL PLAINS  
TOWARD THE OZARKS. WARM, MOIST SOUTHERLY AIR INTERSECTING THE  
BOUNDARY WILL LIKELY LEAD TO STRONG THUNDERSTORMS THAT MAY TRAIN  
OR REPEAT OVER THE SAME AREAS SUNDAY INTO MONDAY. SEVERAL  
MESOSCALE CONVECTIVE SYSTEMS REPEATING OVER THE AREA COULD LEAD TO  
LARGE FOOTPRINT OF MULTI-INCH TOTALS AND THE LATEST GUIDANCE  
SUGGESTS THE BEST POTENTIAL FOR FLASH FLOODING AND EXCESSIVE  
RAINFALL OVER PORTIONS OF SOUTHERN MISSOURI, NORTHWEST ARKANSAS,  
NORTHEAST OKLAHOMA AND ADJACENT AREAS. A DAY 5 EXPERIMENTAL SLIGHT  
RISK ERO WAS INCLUDED FOR THIS REGION GIVEN THE POTENTIAL - WHERE  
STREAM FLOWS AND PRECIPITATION ANOMALIES ARE ALREADY ABOVE NORMAL  
DUE TO RECENT HEAVY RAINFALL AND WITH THE POTENTIAL FOR ADDITIONAL  
HEAVY RAINFALL LEADING UP TO DAY 5.  
 
EXPECT UNSEASONABLY COLD TEMPERATURES TO PERSIST OVER FAR NORTHERN  
PARTS OF THE PLAINS THROUGH THE PERIOD WITH NORTH DAKOTA IN  
PARTICULAR SEEING HIGHS 15-30F BELOW NORMAL FOR MULTIPLE DAYS.  
THE WEST WILL SEE MORE VARIABLE TEMPERATURES, WITH MINUS 5-15F  
ANOMALIES LATE WEEK INTO THE WEEKEND BUT FOLLOWED BY A  
WEST-TO-EAST MODERATING TREND WITH INCREASING COVERAGE OF ABOVE  
NORMAL READINGS EARLY NEXT WEEK. CLOUDS/PRECIPITATION MAY BRING  
BELOW NORMAL HIGHS TO THE PACIFIC NORTHWEST NEXT TUESDAY THOUGH.  
A MAJOR WARMING TREND IS LIKELY FOR THE CENTRAL/SOUTHERN PLAINS ON  
FRIDAY AND THEN MUCH OF THE EASTERN HALF OF THE NATION GOING INTO  
THE WEEKEND. CENTRAL PLAINS LOCATIONS COULD SEE HIGHS UP TO  
20-30F ABOVE NORMAL ON FRIDAY. PLUS 10-20F ANOMALIES SHOULD BE  
MORE COMMON FARTHER EAST. ALSO HUMIDITY LEVELS SHOULD INCREASE IN  
RESPONSE TO DEEP SOUTHERLY FLOW AHEAD OF THE CENTRAL U.S. STORM  
SYSTEM. ONE EXCEPTION TO THE EASTERN WARMTH SHOULD BE OVER THE  
NORTHEAST/NORTHERN MID-ATLANTIC WHERE COOL SURFACE HIGH  
PRESSURE/RIDGING MAY PREVAIL FOR MULTIPLE DAYS. A BACK DOOR FRONT  
EXPECTED TO SETTLE OVER THE MID-ATLANTIC COULD PROVIDE A SHARP  
CONTRAST BETWEEN COOL AIR TO THE NORTH AND WARMTH TO THE SOUTH AND  
WEST.  
 
TAYLOR  
 
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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