996  
FXUS02 KWBC 251900  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT WED MAY 25 2022  
 
VALID 12Z SAT MAY 28 2022 - 12Z WED JUN 01 2022  
   
..WEATHER PATTERN OVERVIEW
 
 
BEHIND A DEPARTING EASTERN U.S. UPPER TROUGH AND EMBEDDED LOW,  
GUIDANCE IS AGREEABLE AND CONSISTENT WITH DEVELOPING A VERY  
AMPLIFIED WESTERN TROUGH/EASTERN RIDGE PATTERN WHOSE SLOW  
EVOLUTION RAISES THE POTENTIAL FOR A PERIOD OF SIGNIFICANT  
PRECIPITATION FROM THE NORTHERN ROCKIES INTO THE NORTHERN-CENTRAL  
PLAINS AND UPPER MIDWEST. A SYSTEM REACHING THE PACIFIC NORTHWEST  
COAST ON SATURDAY MAY ALSO BRING A BRIEF PERIOD OF LOCALLY  
MODERATE TO HEAVY PRECIPITATION TO THAT PART OF THE COUNTRY.  
SCATTERED RAINFALL MAY DEVELOP OVER PARTS OF THE SOUTH HEADING  
TOWARD THE MIDDLE OF NEXT WEEK, DEPENDING ON UNCERTAIN DETAILS OF  
UPPER ENERGY THAT COULD TRY TO RETROGRADE UNDERNEATH THE EASTERN  
U.S. RIDGE. THIS PATTERN EVOLUTION WILL GRADUALLY SHIFT MUCH  
ABOVE NORMAL TEMPERATURES FROM THE PLAINS MORE INTO THE NORTHERN  
HALF OR TWO-THIRDS OF THE EAST WHILE IT SPREADS MUCH BELOW NORMAL  
TEMPERATURES (ESPECIALLY FOR HIGHS) THROUGH THE WEST AND INTO THE  
NORTHERN PLAINS.  
   
..MODEL GUIDANCE AND PREFERENCES
 
 
WITHIN THE AGREEABLE AND CONSISTENT LARGE SCALE FORECAST,  
INDIVIDUAL MODELS AND ENSEMBLES DIFFER WITH SOME IMPORTANT DETAILS  
THAT WILL AFFECT SENSIBLE WEATHER SPECIFICS AT SOME LOCATIONS.  
NEAR THE EAST COAST, GUIDANCE CONTINUES TO HAVE DIFFICULTY WITH  
HANDLING THE WEEKEND UPPER TROUGH/LOW. CONSENSUS FROM THE 00Z/06Z  
PACKAGE APPEARED TO HAVE NUDGED SOMEWHAT SLOWER THAN THE MAJORITY  
FROM THE PRIOR 12Z CYCLE. THE 06Z GFS WAS ON THE EXTREME SLOW  
SIDE BUT BOTH THE 00Z/06Z GFS RUNS HOLD IT FAR ENOUGH BACK TO  
RESULT IN AN ULTIMATE PATH TOWARD THE SOUTHEAST COAST AS UPPER  
RIDGING BUILDS TO THE WEST/NORTH. REMAINING GUIDANCE AND THE 12Z  
GFS ARE MORE PROGRESSIVE WITH THE MAIN TROUGH/LOW, WITH ONLY  
LINGERING SOUTHERN PERIPHERY ENERGY SERVING AS ANY FEATURE THAT  
COULD SLIDE BENEATH THE UPPER RIDGE. MEANWHILE, THE 12Z MODELS  
ARE SHOWING A SIGNIFICANT CONSOLIDATION TOWARD A MORE GFS-LIKE  
SOLUTION (THOUGH NOT AS STRONG AS THE 06Z RUN) FOR THE COMPACT BUT  
POTENTIALLY VIGOROUS SYSTEM EXPECTED TO REACH THE PACIFIC  
NORTHWEST COAST ON SATURDAY. MODELS GENERALLY AGREE THAT THIS AND  
SURROUNDING DYNAMICS SHOULD YIELD A CLOSED LOW THAT TRACKS  
APPROXIMATELY THROUGH THE NORTHWEST/GREAT BASIN INTO NORTHERN  
ROCKIES DURING SUNDAY-TUESDAY. HOWEVER FROM MONDAY ONWARD THERE  
IS ENOUGH SPREAD FOR THE EXACT PATH/STRENGTH/TIMING OF THE UPPER  
LOW AND SHORTWAVE DETAILS AHEAD OF IT TO LOWER CONFIDENCE IN  
SPECIFICS OF THE WAVY SURFACE BOUNDARY SETTING UP OVER THE  
ROCKIES/CENTRAL U.S. ALONG WITH ACCOMPANYING SIGNIFICANT  
PRECIPITATION. DEVELOPING DIFFERENCES UPSTREAM OVER THE PACIFIC  
MAY BEGIN TO HAVE SOME INFLUENCE TOWARD MIDWEEK AS WELL.  
 
THE UPDATED FORECAST STARTED WITH A BLEND OF THE 00Z/06Z GFS AND  
00Z ECMWF/UKMET/CMC FOR ABOUT THE FIRST HALF OF THE PERIOD,  
LEADING TO A CONSERVATIVE FORECAST FOR THE INITIAL EAST COAST  
TROUGH/LOW AND INTERMEDIATE/CONSENSUS FORECAST ACROSS THE WEST,  
WITH THE AMPLIFYING UPPER TROUGH LIKELY REACHING ITS GREATEST  
DEPTH AROUND MONDAY. WIDENING DETAIL SPREAD LATER IN THE PERIOD  
FAVORED MAINTAINING A BLENDED MODEL/ENSEMBLE MEAN APPROACH BY  
TUESDAY-WEDNESDAY.  
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
ON SATURDAY A COMPACT BUT POTENTIALLY VIGOROUS SYSTEM SHOULD BRING  
A BRIEF EPISODE OF LOCALLY MODERATE TO HEAVY PRECIPITATION AND  
POSSIBLY BRISK WINDS TO PARTS OF THE PACIFIC NORTHWEST ON  
SATURDAY. THIS SYSTEM AND ITS MOISTURE WILL CONTRIBUTE TO A  
LARGER SCALE UPPER LOW TRACKING INTO/THROUGH THE WEST DURING THE  
WEEKEND INTO NEXT WEEK AND REINFORCE A LEADING WAVY FRONTAL  
ALREADY IN PLACE OVER THE CENTRAL U.S. DURING THE WEEKEND. SOME  
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER THE NORTHERN  
PLAINS/UPPER MIDWEST DURING THE WEEKEND WITH THIS LEADING FRONT,  
WHILE THE COMBINATION OF THE WESTERN UPPER LOW AND DEVELOPING LOW  
LEVEL UPSLOPE FLOW COULD PRODUCE A MULTI-DAY PERIOD OF HEAVY  
PRECIPITATION POTENTIAL OVER AND JUST EAST OF THE NORTHERN ROCKIES  
FROM THE WEEKEND INTO NEXT WEEK. THIS MAY INCLUDE HEAVY SNOW AT  
HIGH ELEVATIONS WITHIN THE NORTHERN ROCKIES. BY THE MIDDLE OF  
NEXT WEEK RAINFALL MAY BECOME HEAVIER ALONG THE WAVY FRONT OVER  
THE CENTRAL PLAINS. THE UPPER TROUGH/LOW INITIALLY NEAR THE EAST  
COAST COULD PRODUCE SOME SCATTERED SHOWERS/THUNDERSTORMS ON  
SATURDAY FOLLOWED BY A DRIER TREND OVER MOST OF THE EAST.  
DEPENDING ON HOW ENERGY ALOFT TO THE SOUTH OF THE BUILDING EASTERN  
RIDGE EVOLVES, SOME SHOWERS/STORMS COULD DEVELOP OVER PARTS OF THE  
SOUTH TOWARD MIDWEEK. THE FLORIDA PENINSULA SHOULD SEE EPISODES  
OF SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD.  
 
TEMPERATURES WILL BE QUITE WARM ACROSS THE CENTRAL AND SOUTHERN  
PLAINS DURING THE WEEKEND INTO THE START OF NEXT WEEK WITH HIGHS  
REACHING WELL INTO THE 90S FROM SOUTHERN NEBRASKA TO THE GULF  
COAST, AND ON SATURDAY-SUNDAY SOME LOW-MID 100S ACROSS WESTERN  
TEXAS WHICH COULD CHALLENGE SOME DAILY RECORDS. THE HEAT WILL  
THEN BUILD EASTWARD/NORTHEASTWARD AS UPPER RIDGING STRENGTHENS  
OVER THE EAST, WITH PLUS 10-20F ANOMALIES BECOMING INCREASINGLY  
ENTRENCHED OVER THE GREAT LAKES/OHIO VALLEY/NORTHEAST. WELL BELOW  
NORMAL TEMPERATURES WILL GRADUALLY PROGRESS FROM WEST TO EAST  
ACROSS THE WEST AND INTO THE NORTHERN PLAINS AS UPPER TROUGHING  
DEEPENS AND THEN PERSISTS OVER THE WESTERN U.S. EXPECT ONE OR  
MORE DAYS WITH HIGHS 10-20F BELOW NORMAL AND POSSIBLY LOCALIZED  
COLDER READINGS OVER PARTS OF THE NORTHERN ROCKIES/HIGH PLAINS.  
 
RAUSCH/HAMRICK  
 
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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