498  
FXUS02 KWBC 260700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
259 AM EDT TUE APR 26 2022  
 
VALID 12Z FRI APR 29 2022 - 12Z TUE MAY 03 2022  
   
..OVERVIEW
 
 
AN UPPER TROUGH WITH ITS AXIS OVER THE INTERMOUNTAIN WEST AS THE  
MEDIUM RANGE PERIOD BEGINS FRIDAY WILL PUSH EASTWARD INTO THE  
NORTH-CENTRAL U.S. THROUGH THE WEEKEND AS IT FORMS A CLOSED UPPER  
LOW. A SURFACE LOW IS LIKELY TO CONSOLIDATE IN CONJUNCTION WITH  
THE TROUGH/LOW, SPREADING RAIN TO MUCH OF THE CENTRAL U.S. WHILE  
SNOW IS FORECAST ON THE BACKSIDE OF THE LOW ACROSS THE NORTHERN  
ROCKIES WITH SOME CHANCE OF WINTRY WEATHER SPREADING INTO THE  
NORTHERN HIGH PLAINS AS WELL, ALTHOUGH THE DETAILS OF  
PRECIPITATION AMOUNTS AND PLACEMENT REMAIN UNCERTAIN AT THIS  
POINT. MEANWHILE, SURFACE AND UPPER LOWS WILL MOVE SLOWLY AWAY  
FROM THE NORTHEAST OVER THE WEEKEND AFTER SPREADING SOME LIGHT TO  
MODERATE RAIN AND SNOW ACROSS THE AREA FOR THE LATTER PART OF THE  
WEEK. PERIODIC UNSETTLED WEATHER IS EXPECTED IN THE WEST AS A  
SERIES OF UPPER TROUGHS AND FRONTAL SYSTEMS MOVE THROUGH.  
 
   
..MODEL GUIDANCE EVALUATION
 
 
MODEL GUIDANCE REMAINS QUITE AGREEABLE IN KEEPING A LOW PRESSURE  
SYSTEM (BOTH IN THE UPPER LEVELS AND AT THE SURFACE) MOVING SLOWLY  
OVER THE CANADIAN MARITIMES THROUGH THE WEEKEND. ADDITIONALLY,  
MODELS HAVE GENERALLY CONVERGED ON A SOLUTION WITH A TROUGH  
INITIALLY ACROSS THE INTERMOUNTAIN WEST DEVELOPING INTO A CLOSED  
LOW AS IT MOVES OVER THE CENTRAL/NORTHERN PLAINS AND MIDWEST OVER  
THE WEEKEND, BUT WITH STILL SOME SLIGHT WIGGLES IN LATITUDINAL  
POSITION. THE ASSOCIATED SURFACE LOW TRACK IS FAIRLY AGREEABLE AS  
WELL, WITH THE ECMWF PERHAPS ON THE WESTERN SIDE AND GFS RUNS ON  
THE SOUTHEASTERN SIDE OF THE SPREAD IN TERMS OF THE 12/18Z CYCLE,  
BUT WITHIN TYPICAL MEDIUM RANGE SPREAD. THE NEWER 00Z ECWMF AND  
GFS SHOW GOOD CLUSTERING WITH THE LOW THROUGH AT LEAST SUNDAY.  
THERE IS ALSO BETTER CONSENSUS IN RECENT GUIDANCE FOR THE UPPER  
LOW TO WEAKEN AND LIFT INTO CANADA EARLY NEXT WEEK. THE EARLY PART  
OF THE WPC FORECAST WAS BASED MAINLY ON A BLEND OF THE 18Z GFS AND  
12Z ECMWF AND UKMET.  
 
UPSTREAM, MOST GUIDANCE HAS AN ADDITIONAL TROUGH/LOW APPROACHING  
AND ENTERING THE NORTHWEST OVER THE WEEKEND. THE MAJOR OUTLIER  
WITH THIS FEATURE WAS THE 12Z CMC, WHICH HAS A MUCH WEAKER  
SHORTWAVE AND THUS BY AROUND SUNDAY-MONDAY PRODUCES A PATTERN  
RATHER OUT OF PHASE WITH OTHER GUIDANCE, WITH STRONG RIDGING IN  
THE WEST. THE NEWER 00Z CMC CAME IN CLOSER TO CONSENSUS WITH THIS  
FEATURE. BUT DETERMINISTIC MODELS AS WELL AS ENSEMBLE MEMBERS SHOW  
DIFFERENCES IN HANDLING THAT SHORTWAVE MONDAY AND BEYOND AS WELL  
AS WHAT COULD BE STRONG ENERGY COMING IN BEHIND IT. THUS THE WPC  
FORECAST PHASED IN THE ENSEMBLE MEANS BY THE LATTER PART OF THE  
FORECAST PERIOD GIVEN THE DIFFERENCES, PARTICULARLY FAVORING THE  
12Z EC AND CMC ENSEMBLE MEANS THAT WERE PRETTY AGREEABLE WITH A  
SLIGHTLY SLOWER TROUGH IN THE WEST COMPARED TO THE GEFS MEAN.  
 
   
..SENSIBLE WEATHER/THREATS
 
 
THE SURFACE LOW PRESSURE SYSTEM WILL SPREAD PRECIPITATION ACROSS  
MUCH OF THE CENTRAL U.S. LATE THIS WEEK THAT SHOULD SPREAD INTO  
THE EAST OVER THE WEEKEND. PRECIPITATION TOTALS ARE LIKELY TO BE  
ENHANCED ACROSS NORTHERN/CENTRAL PARTS OF THE PLAINS NEAR THE  
CONSOLIDATING SURFACE LOW. CONDITIONS WILL LIKELY BE COLD ENOUGH  
FOR SNOW IN THE NORTHERN ROCKIES ON THE BACKSIDE OF THE LOW, AND  
THERE IS ONCE AGAIN SOME THREAT OF WINTRY PRECIPITATION SPREADING  
INTO THE NORTHERN HIGH PLAINS AS WELL. 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 FOR THE LATTER PART OF THIS WEEK.  
PRECIPITATION CHANCES ARE EXPECTED TO SPREAD EASTWARD INTO EARLY  
NEXT WEEK AS THE LOW SLOWLY MOVES EAST, BUT LINGER IN THE CENTRAL  
U.S. AS WELL AS THE FRONT THERE MAY STALL. ELSEWHERE, 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.  
THE NORTHEAST COULD SEE LINGERING PRECIPITATION LATE THIS WEEK  
BEFORE THE COASTAL SURFACE LOW AND UPPER LOW PULL AWAY.  
 
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 NORTHEASTERN QUADRANT OF THE  
COUNTRY CAN EXPECT BELOW AVERAGE TEMPERATURES BY 5-15F ON FRIDAY  
BUT MODERATING NEAR NORMAL BY EARLY NEXT WEEK. HIGHS WILL REMAIN  
COLDER THAN NORMAL BY AROUND 15-25F ACROSS THE NORTH-CENTRAL U.S.  
UNDERNEATH UPPER TROUGHING. MEANWHILE, THE CENTRAL/SOUTHERN HIGH  
PLAINS SHOULD SEE WARMER THAN NORMAL TEMPERATURES BY UP TO 20F ON  
FRIDAY BEFORE THE UPPER RIDGE PROMOTING THE WARMTH IS SUPPRESSED  
OVER THE WEEKEND. SLIGHTLY ABOVE NORMAL TEMPERATURES SHOULD THEN  
STRETCH ACROSS MUCH OF THE SOUTHERN TIER.  
 
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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