820  
FXUS02 KWBC 240701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT THU MAR 24 2022  
 
VALID 12Z SUN MAR 27 2022 - 12Z THU MAR 31 2022  
   
..OVERVIEW
 
 
NEXT WEEK AN UPPER TROUGH WITH A LIKELY EMBEDDED LOW IS FORECAST  
TO MOVE FROM THE EASTERN PACIFIC INTO THE WEST AND THEN INTO THE  
CENTRAL U.S. BY AROUND MIDWEEK. THIS PATTERN WILL LEAD TO  
INCREASING PRECIPITATION CHANCES IN THE WEST EARLY IN THE WEEK  
BEFORE A DEEPENING LOW IN THE PLAINS SPREADS RAIN AND  
THUNDERSTORMS TO THE SOUTH-CENTRAL U.S. AND POSSIBLE SPRINGTIME  
SNOW TO THE NORTHERN TIER. AN UPPER RIDGE INITIALLY OVER THE WEST  
CAUSING WARM WEATHER FOR THE WEST COAST TO PLAINS WILL BE SHUNTED  
EAST BY THE TROUGH, WITH MODERATING TEMPERATURES. MEANWHILE MEAN  
TROUGHING AND COASTAL LOW PRESSURE SYSTEMS IN THE EAST SHOULD  
BRING COOL TEMPERATURES AND LIGHT PRECIPITATION EARLY IN THE WEEK.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
FORTUNATELY, MODEL GUIDANCE FROM THE 12/18Z YESTERDAY CYCLE SHOWS  
BETTER AGREEMENT OVERALL COMPARED TO THE PAST COUPLE OF DAYS,  
PARTICULARLY WITH THE UPPER TROUGH MOVING THROUGH THE  
WESTERN/CENTRAL U.S. MODELS CONTINUE TO SHOW GOOD CONSENSUS WITH  
THE RIDGE AXIS OVER THE ROCKIES AND TROUGHING ACROSS THE EAST AT  
THE START OF THE PERIOD SUNDAY, WITH THE DEEPER TROUGH/LOW ACROSS  
THE EASTERN PACIFIC. AFTER SEVERAL DAYS OF WAFFLING WITH TIMING OF  
THE TROUGH PARTIALLY RELATED TO PHASING OR STREAM SEPARATION  
BETWEEN AN UPPER LOW WITHIN THE TROUGH AND A NORTHERN STREAM  
SHORTWAVE, GUIDANCE IS NOW BETTER ALIGNED WITH SHOWING MORE  
PHASING OR AT LEAST CONNECTION BETWEEN THE TWO FEATURES  
MONDAY/TUESDAY. THIS FAVORS A MODERATELY PROGRESSIVE TROUGH  
WITHOUT LEAVING A SOUTHERN STREAM LOW BEHIND LIKE EARLIER ECMWF  
RUNS DID. THE RIDGE AXIS SHOULD BE FLATTENED AND PUSHED EASTWARD  
SOMEWHAT BY THE TROUGH WHILE THE EASTERN TROUGH SHOULD LIFT, AND  
MODELS ARE FAIRLY PERSISTENT WITH THOSE FEATURES.  
 
BY AROUND WEDNESDAY, MORE DIFFERENCES IN THE TROUGH AXIS DO ARISE  
AS 12/18Z AND THE NEWER 00Z GFS RUNS MAINTAIN A CLOSED LOW IN THE  
CENTRAL U.S. WITHIN A NEUTRAL TROUGH AXIS. ECMWF AND CMC RUNS SHOW  
MORE PHASING BY WEDNESDAY (THOUGH PERHAPS WITH SOME SEPARATION  
AGAIN ON THURSDAY) WITHIN A SLIGHTLY POSITIVELY TILTED TROUGH.  
THESE ISSUES STEM AT LEAST PARTLY FROM STRENGTH AND TIMING OF THE  
NORTHERN STREAM SHORTWAVES, AND THESE DIFFERENCES MAY TAKE SOME  
TIME TO BE IRONED OUT. BUT AT LEAST THE OVERALL PATTERN IS COMING  
INTO SHAPE, AND AGREEMENT FOR A SURFACE LOW STRENGTHENING IN THE  
CENTRAL PLAINS TUESDAY IS GOOD, BUT WITH SOME DIFFERENCES IN TRACK  
AFTER THAT.  
 
THUS THE WPC FORECAST BEGAN WITH A MULTI-MODEL DETERMINISTIC BLEND  
OF THE 18Z GFS AND 12Z ECMWF, CMC, AND UKMET. PHASED IN THE GEFS  
AND EC ENSEMBLE MEANS TO ABOUT HALF BY THE END OF THE PERIOD TO  
ADDRESS THE UNCERTAINTY IN THE DETAILS OF THE PATTERN.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
LIGHT PRECIPITATION COULD LINGER ACROSS THE GREAT LAKES REGION AND  
NORTHEAST EARLY NEXT WEEK GIVEN STRONG CYCLONIC FLOW AND COASTAL  
LOW PRESSURE SYSTEMS. AS THE NEXT SYSTEM MOVES INTO THE WESTERN  
U.S. EARLY NEXT WEEK, UNSETTLED AND ACTIVE WEATHER IS EXPECTED FOR  
THE WEST COAST STATES SUNDAY, WHICH COULD BRING MOSTLY BENEFICIAL  
AND WELCOME RAINS TO THE VALLEYS, WITH THE HIGHER ELEVATION AREAS  
OF THE SIERRA COULD SEE SEE SEVERAL INCHES OR MORE OF SNOW.  
CURRENT MODEL GUIDANCE SHOWS THE HEAVIEST RAIN TOTALS FOR SOUTHERN  
CALIFORNIA SUNDAY AND MONDAY ESPECIALLY ENHANCED BY HIGHER  
TERRAIN, WHICH COULD CAUSE FLOODING ISSUES IF HEAVY RAIN FALLS  
OVER BURN SCAR AREAS. RAIN AND HIGHER ELEVATION SNOW WILL SPREAD  
ACROSS THE INTERMOUNTAIN WEST AND ROCKIES MONDAY AND TUESDAY. AS  
SURFACE LOW PRESSURE STRENGTHENS IN THE PLAINS AND TRACKS EAST,  
MORE WIDESPREAD RAIN AND THUNDERSTORMS ARE LIKELY FOR THE  
SOUTH-CENTRAL U.S. TUESDAY AND WEDNESDAY. MEANWHILE ON THE  
NORTHERN SIDE OF THE PRECIPITATION SHIELD, WINTRY MIX AND SNOW ARE  
POSSIBLE FOR THE NORTH-CENTRAL U.S. AND POTENTIALLY INTO THE  
NORTHEAST, BUT DETAILS ARE LACKING THAT FAR OUT IN TIME.  
 
UNSEASONABLY WARM TEMPERATURES ARE LIKELY UNDERNEATH UPPER RIDGING  
FROM THE WESTERN U.S. INTO THE PLAINS EARLY NEXT WEEK, AND  
TEMPERATURES OF 10-25F ABOVE NORMAL WILL BE COMMON. THOUGH MUCH OF  
THE RECORD-BREAKING WARMTH MAY HAVE PHASED INTO THE SHORT RANGE  
PERIOD, SOME RECORD HIGHS AND HIGH MINIMUM TEMPERATURES COULD BE  
SET OR TIED SUNDAY AND MONDAY. TEMPERATURES IN THE WEST WILL  
MODERATE CLOSER TO NORMAL AS THE TROUGH APPROACHES, WHILE WARMER  
THAN AVERAGE TEMPERATURES SHOULD PUSH INTO THE SOUTHEASTERN U.S.  
AND MODERATE AS THE WEEK PROGRESSES. MEANWHILE THE EAST SHOULD SEE  
BELOW AVERAGE TEMPERATURES GIVEN MEAN UPPER TROUGHING, WITH HIGHS  
OF 10-25F AND LOWS OF 10-15F BELOW NORMAL OVER THE GREAT LAKES AND  
CENTRAL APPALACHIANS FOR THE WEEKEND AND SPREADING INTO THE  
NORTHEAST EARLY NEXT WEEK. THESE AREAS ARE FORECAST TO WARM NEARER  
TO NORMAL AROUND MIDWEEK.  
 
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  
 
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/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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