082  
FXUS02 KWBC 050700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
259 AM EDT TUE APR 05 2022  
 
VALID 12Z FRI APR 08 2022 - 12Z TUE APR 12 2022  
   
..OVERVIEW
 
 
TODAY'S GUIDANCE IS CONSISTENT IN ADVERTISING A DRAMATIC SWITCH IN  
THE AMPLIFIED UPPER LEVEL PATTERN FROM LATE THIS WEEK INTO NEXT  
WEEK, WITH AN INITIAL WESTERN RIDGE/EASTERN TROUGH ULTIMATELY  
EVOLVING TO A WESTERN TROUGH/EASTERN RIDGE. THIS EVOLUTION WILL  
LEAD TO SOME DRAMATIC TEMPERATURE CHANGES DURING THE PERIOD AS  
MUCH ABOVE NORMAL TEMPERATURES OVER THE WEST ON FRIDAY TREND  
TOWARD WELL BELOW NORMAL READINGS BY THE FIRST PART OF NEXT WEEK  
AND CHILLY TEMPERATURES OVER THE EASTERN HALF OF THE COUNTRY  
FRIDAY INTO THE WEEKEND REBOUND TO ABOVE NORMAL LEVELS BY EARLY  
NEXT WEEK. MEANWHILE RAIN AND HIGHER ELEVATION SNOW WILL SPREAD  
OVER THE WEST AND LOW LEVEL GULF INFLOW SHOULD EVENTUALLY  
CONTRIBUTE TO RAINFALL OVER THE MISSISSIPPI VALLEY AND VICINITY.  
A SHOWERY PATTERN OVER THE EAST DURING FRIDAY-SATURDAY UNDER THE  
UPPER TROUGH SHOULD GIVE WAY TO DRIER WEATHER THEREAFTER.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
12Z/18Z OPERATIONAL MODELS WERE IN GOOD AGREEMENT FOR MOST ASPECTS  
OF THE FORECAST DURING THE FIRST HALF OF THE PERIOD. THE MAIN  
EXCEPTION WAS WITH THE 18Z GFS DEPICTION OF A QUESTIONABLY STRONG  
SHORTWAVE (WITH AN EMBEDDED UPPER LOW) CROSSING THE NORTHERN  
PLAINS AND SOUTHERN CANADA AROUND SUNDAY. RECENTLY THERE HAVE  
BEEN SOME MODEST TRENDS TOWARD MORE HEIGHT FALLS REACHING ACROSS  
THE NORTHERN TIER AND SOUTHERN CANADA, PUSHING THE PLAINS COLD  
FRONT A LITTLE FARTHER SOUTHEAST, BUT THE 18Z GFS SPECIFICS HAVE  
MINIMAL SUPPORT FROM OTHER MODEL/ENSEMBLE GUIDANCE. THE NEW 00Z  
GFS SHOWS FAVORABLE TRENDS. CONSENSUS STILL SHOWS AN UPPER LOW  
OVER THE GREAT LAKES AS OF FRIDAY, FOLLOWED BY UNCERTAINTY OVER  
EXACTLY HOW THE CORE OF THE UPPER TROUGH WILL EVOLVE AS IT LIFTS  
OUT. THE UPDATED FORECAST USING AN OPERATIONAL MODEL COMPOSITE  
KEPT 18Z GFS WEIGHT LOW ENOUGH TO MINIMIZE THE QUESTIONABLE  
DETAILS OVER THE NORTHERN PLAINS BY SUNDAY.  
 
FROM LATE WEEKEND THROUGH NEXT TUESDAY THE PRIMARY FOCUS OF THE  
FORECAST WILL BE THE DEEPENING UPPER TROUGH OVER THE WEST, WITH A  
POTENTIAL EMBEDDED GREAT BASIN UPPER LOW ORIGINATING FROM ENERGY  
OVER THE GULF OF ALASKA AT THE START OF THE PERIOD. RECENT  
ECMWF/CMC RUNS HAVE BEEN FAIRLY CONSISTENT WITH THIS EVOLUTION, AS  
HAVE THE ENSEMBLE MEANS. THE 18Z AND 00Z GFS RUNS LOOK BETTER  
AFTER THE 12Z RUN WAS SUSPICIOUSLY SLOW TO BRING THIS ENERGY INTO  
THE WEST. FARTHER EAST THERE IS SOME SPREAD FOR HOW SHORTWAVE  
ENERGY MAY ROUND THE EASTERN RIDGE, WITH EFFECTS ON A SURFACE  
FRONT EXPECTED TO EXTEND FROM THE PLAINS INTO THE GREAT LAKES (AND  
POSSIBLY BEYOND) BY DAY 7 TUESDAY. A BLEND OF THE 18Z GFS/12Z  
ECMWF-CMC AND 18Z GEFS/ECMWF MEAN REPRESENTED THE CONSENSUS WELL  
WHILE ACCOUNTING FOR TYPICALLY INCREASING DETAIL UNCERTAINTY.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
THE UPPER TROUGH AMPLIFYING INTO THE WEST WILL SPREAD RAIN AND  
HIGHER ELEVATION SNOW ACROSS NORTHERN AND CENTRAL PARTS OF THE  
REGION, EVENTUALLY REACHING SOME SOUTHERN AREAS LATE IN THE  
PERIOD. BEST POTENTIAL FOR SOME ENHANCEMENT BEYOND LIGHT/MODERATE  
ACTIVITY WILL BE OVER FAVORED TERRAIN IN THE CASCADES LATE THIS  
WEEK INTO THE WEEKEND AND THEN THE NORTHERN-CENTRAL ROCKIES BY  
SUNDAY-MONDAY AND POSSIBLY INTO TUESDAY. LOW LEVEL UPSLOPE FLOW  
MAY ADD TO PRECIPITATION TOTALS ALONG THE ROCKIES. FARTHER EAST,  
EXPECT RAIN TO DEVELOP OVER THE MISSISSIPPI VALLEY AND VICINITY  
DURING THE FIRST HALF OF NEXT WEEK WITH AN INCREASING FLOW OF GULF  
MOISTURE. THE MAIN AREA OF ORGANIZED RAINFALL WITH THE BROAD  
SYSTEM AFFECTING THE EAST LATE THIS WEEK SHOULD DEPART FROM NEW  
ENGLAND ON FRIDAY WITH THE NORTHWARD PROGRESSION OF A FRONTAL  
WAVE. HOWEVER COLD AIR ALOFT ASSOCIATED WITH THE UPPER TROUGH  
WILL LIKELY PROMOTE AREAS OF DIURNALLY ENHANCED SHOWERS FROM THE  
MIDWEST INTO THE NORTHERN HALF TO TWO-THIRDS OF THE EAST INTO  
FRIDAY-SATURDAY. SOME PRECIPITATION COULD BE IN THE FORM OF SNOW  
BETWEEN THE MIDWEST AND APPALACHIANS.  
 
THE WEST WILL SEE ONE MORE DAY OF VERY WARM TO HOT TEMPERATURES ON  
FRIDAY WITH HIGHS REACHING 15-25F ABOVE NORMAL ESPECIALLY FROM  
CALIFORNIA INTO THE GREAT BASIN, WITH SOME DAILY RECORDS FOR  
HIGHS/WARM LOWS. THEN THE UPPER TROUGH STEADILY DEEPENING OVER THE  
REGION WILL BRING A PRONOUNCED COOLING TREND. MUCH OF THE  
NORTHWEST/NORTHERN ROCKIES MAY SEE HIGHS OF 10-15F BELOW NORMAL BY  
SUNDAY AND HIGHS OF 10-20F BELOW NORMAL SHOULD BE COMMON OVER A  
MAJORITY OF THE WEST AS WELL AS NORTHERN HIGH PLAINS BY NEXT  
TUESDAY. MEANWHILE THE EASTERN HALF OF THE COUNTRY WILL TREND  
FROM MOSTLY BELOW NORMAL TEMPERATURES (UP TO MINUS 10-20F  
ANOMALIES) FRIDAY-SATURDAY TO ABOVE NORMAL READINGS (PLUS 5-15F  
ANOMALIES) FROM WEST TO EAST BY NEXT SUNDAY-TUESDAY.  
 
RAUSCH  
 
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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