554  
FXUS02 KWBC 210632  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
231 AM EDT THU APR 21 2022  
 
VALID 12Z SUN APR 24 2022 - 12Z THU APR 28 2022  
 
...SIGNIFICANT LATE SEASON WINTER STORM THIS WEEKEND ALONG WITH  
POTENTIALLY HEAVY RAINFALL OVER PORTIONS OF THE SOUTHERN PLAINS  
AND MID-MS RIVER VALLEY...  
   
..WEATHER PATTERN OVERVIEW
 
 
AN AMPLIFIED FLOW PATTERN IS EXPECTED TO START THE PERIOD AS THE  
NORTHERN PLAINS DEEP LOW LIFTS INTO CANADA WHILE A STRONG  
SOUTHEAST RIDGE EXTENDS NORTHWARD THROUGH MUCH OF THE EASTERN  
U.S.. THE ASSOCIATED TRAILING COLD FRONT SOUTHWARD COULD BRING A  
LOCALIZED HEAVY RAINFALL THREAT SUNDAY INTO MONDAY OVER PORTIONS  
OF THE SOUTHERN PLAINS TO THE OZARKS AND MID MISSISSIPPI VALLEY.  
BY TUESDAY-WEDNESDAY, GRADUAL PROGRESSION OF THE MEAN PATTERN WILL  
BRING MODERATE UPPER TROUGHING TO THE EAST, A RIDGE TO THE  
ROCKIES/PLAINS, AND A TROUGH INTO THE EASTERN PACIFIC/WEST COAST.  
MUCH BELOW NORMAL TEMPERATURES MAY PERSIST FOR A WHILE OVER THE  
FAR NORTHERN PARTS OF THE PLAINS WHILE WELL ABOVE NORMAL READINGS  
ARE POSSIBLE OVER A MAJORITY OF THE EASTERN HALF OF THE COUNTRY  
THROUGH THE WEEKEND.  
   
..MODEL GUIDANCE EVALUATION
 
 
THIS FORECAST CYCLE THE MODEL AGREEMENT REMAINS FAIRLY CLUSTERED  
AND AGREEABLE ASIDE FROM THE CMC AND TO SOME DEGREE THE UKMET  
WHICH WERE SLOWER WITH THE PROGRESSION OF THE TROUGH AXIS MOVING  
FROM THE NORTHERN TIER TOWARD THE NORTHEAST. THE ECMWF CONTINUED  
TO BE THE BEST PROXY THROUGH THE PERIOD AS THE GFS WAS ON THE  
FASTER SIDE OF THE MODEL SPREAD BUT OVERALL THE GFS/ECMWF SHOW  
FAIRLY GOOD AGREEMENT THROUGH MUCH OF THE FORECAST PERIOD SUCH  
THAT HIGHER WEIGHTS OF THE TWO WERE INCLUDED IN THE FORECAST BLEND  
THIS CYCLE. HOW THE NORTHEAST CLOSED LOW EVOLVES MID TO LATE WEEK  
IS STILL UNCERTAIN AND THE TIMING OF THE NEXT SYSTEM IN THE  
NORTHWEST HAS CONTINUED UNCERTAINTY BUT THROUGH DAY 6-7, THE  
DETERMINISTIC RUNS OFFERED ENOUGH VALUE TO BE CONSIDERED. TO  
MAINTAIN SOME CONTINUITY, THE ECENS/GEFS MEANS WERE INCLUDED DAYS  
5-7.  
   
..SENSIBLE WEATHER/THREATS
 
 
THE STRONG/SIGNIFICANT WINTER STORM AFFECTING THE NORTHERN PLAINS  
WILL BE CONTINUING AT THE START OF THE MEDIUM RANGE WITH THE  
SURFACE LOW LIKELY TO BE CENTERED ACROSS NORTHERN MINNESOTA. WRAP  
AROUND PRECIPITATION UNDERNEATH THE CLOSED LOW WILL LIKELY  
CONTINUE SNOW SHOWERS AND WITH A STRONG/TIGHT PRESSURE GRADIENT,  
STRONG WINDS WILL LIKELY CONTINUE BLOWING SNOW AND REDUCED  
VISIBILITY AT TIMES. CONDITIONS IMPROVE BY EARLY NEXT WEEK AS THE  
LOW WEAKENS MORE INTO SOUTHERN CANADA. MEANWHILE, FURTHER SOUTH,  
THE TRAILING COLD FRONT SLOWS AND STALLS OVER PORTIONS OF THE  
SOUTHERN PLAINS TO MID-MISSISSIPPI RIVER VALLEY. SOUTHERLY FLOW  
AHEAD OF IT WILL DRAW UP WARM, MOIST AIR THAT INTERSECTS THE  
BOUNDARY. AN INCREASING LOW LEVEL JET SUNDAY NIGHT INTO MONDAY  
MORNING SHOULD FOCUS A FEW MESOSCALE CONVECTIVE SYSTEMS THAT HAVE  
THE POTENTIAL TO TRAIN AND REPEAT OVER THE SAME AREAS. THE LATEST  
FORECAST GUIDANCE SUGGESTS POTENTIAL FOR MULTI-INCH TOTALS DURING  
THE DAY 4 PERIOD (ENDING 12Z MONDAY APRIL 25) ACROSS AN AREA FROM  
NORTHEASTERN TEXAS THROUGH EASTERN OKLAHOMA, WESTERN/NORTHWEST  
ARKANSAS INTO SOUTHERN/SOUTHWEST MISSOURI. THE DAY 4 EXCESSIVE  
RAINFALL OUTLOOK SLIGHT RISK WAS MAINTAINED THIS CYCLE WITH MINOR  
ADJUSTMENTS BASED ON THE LATEST MODEL TRENDS WHICH SHOWED A NUDGE  
TO THE SOUTH/SOUTHEAST FOR THE HEAVY RAIN AXIS. STREAM FLOWS AND  
PRECIPITATION ANOMALIES ARE ABOVE NORMAL FOR MUCH OF THE SLIGHT  
RISK AREA DUE TO RECENT HEAVY RAINFALL AND THERE IS POTENTIAL FOR  
ADDITIONAL RAINFALL LEADING UP TO DAY 4. GUIDANCE IS STILL IN THE  
PROCESS OF RESOLVING THE TIMING AND WAVE DETAILS OF THE SURFACE  
FRONT SO CHANGES IN THE MOST LIKELY COVERAGE AND MAGNITUDE OF  
RAINFALL TOTALS ARE CERTAINLY POSSIBLE. THE FRONT THEN BEGINS TO  
ACCELERATE WITH A PROGRESSIVE AND AMPLIFIED TROUGH AXIS SWINGING  
THROUGH - THIS WILL SPREAD LIGHTER RAINFALL ACROSS MUCH OF THE  
EASTERN U.S. DURING THE TUESDAY THROUGH WEDNESDAY PERIOD.  
GENERALLY UNSETTLED WEATHER BUT LIGHT PRECIPITATION WILL SPREAD  
ACROSS THE NORTHERN PORTIONS OF THE PACIFIC NORTHWEST NEXT WEEK AS  
A SERIES OF SHORTWAVES MOVE THROUGH THE FLOW UNDERNEATH A CLOSED  
UPPER LOW POSITIONED OFF BRITISH COLUMBIA. TIMING AND SPECIFIC  
DETAILS ARE STILL UNCERTAIN IN THE LOWER CONFIDENCE WEATHER  
PATTERN BUT OVERALL SEVERAL OPPORTUNITIES FOR PRECIPITATION THOUGH  
AT THIS TIME NOTHING LOOKS TOO SIGNIFICANT.  
 
THE WEEKEND STORM SYSTEM WILL BRING BOTH MUCH ABOVE NORMAL AND  
MUCH BELOW NORMAL TEMPERATURES TO PORTIONS OF THE CONUS SUNDAY  
THROUGH THE MIDDLE OF NEXT WEEK. AHEAD OF THE SYSTEM, EXPECT  
SEASONABLY WARM TEMPERATURES ACROSS THE EASTERN U.S., ESPECIALLY  
SUNDAY HIGH TEMPERATURES ACROSS THE EASTERN GREAT LAKES WHERE  
HIGHS COULD TOP 20 DEGREES ABOVE NORMAL. WARM TEMPERATURES  
CONTINUE MONDAY BUT TO A LESSER DEGREE. THE EXCEPTION TO THE  
EASTERN WARMTH IS FOR THE COASTAL NORTHEAST AREAS AND PERHAPS INTO  
THE MID-ATLANTIC WHERE SURFACE HIGH PRESSURE PRESENT MAY KEEP  
TEMPERATURES ON THE COOLER SIDE. A FRONT MEANDERING TO THE SOUTH  
COULD LEAD TO A SHARP CONTRAST BETWEEN COOL AIR TO THE NORTH AND  
WARMTH TO THE SOUTH AND WEST, INCREASING THE CHALLENGE OF  
TEMPERATURES FORECASTING OVER THE REGION. THE WEST WILL SEE MORE  
VARIABLE TEMPERATURES, WITH MINUS 5-15F ANOMALIES OVER THE  
INTERMOUNTAIN WEST/ROCKIES LATE IN THE WEEKEND FOLLOWED BY A  
WEST-TO-EAST WARMING TREND WITH INCREASING COVERAGE OF ABOVE  
NORMAL READINGS. WARMEST HIGHS OF 10-15F ABOVE NORMAL ARE LIKELY  
TO EXTEND FROM THE GREAT BASIN/SOUTHWEST INTO THE CENTRAL HIGH  
PLAINS DURING TUESDAY-WEDNESDAY. AT THE SAME TIME  
CLOUDS/PRECIPITATION AHEAD OF THE UPPER TROUGH NEARING THE WEST  
COAST MAY BRING SLIGHTLY BELOW NORMAL HIGHS TO THE PACIFIC  
NORTHWEST.  
 
RAUSCH/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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