463  
FXUS02 KWBC 210655  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
253 AM EDT MON MAR 21 2022  
 
VALID 12Z THU MAR 24 2022 - 12Z MON MAR 28 2022  
   
..OVERVIEW
 
 
AN AMPLIFIED UPPER LEVEL PATTERN WILL BE PRESENT DURING THE MEDIUM  
RANGE PERIOD AS AN ELONGATED UPPER LOW OVER THE MID-MISSISSIPPI  
VALLEY TO UPPER GREAT LAKES THURSDAY LIFTS OUT BUT ADDITIONAL  
ENERGY COMES IN TO MAINTAIN TROUGHING ACROSS THE EAST THROUGH  
EARLY NEXT WEEK. MEANWHILE FARTHER WEST, MEAN RIDGING (THOUGH  
INITIALLY DISRUPTED ON THE NORTHERN SIDE BY A SHORTWAVE) WILL BE  
PRESENT OVER THE WEST AND CAUSE POTENTIALLY RECORD WARMTH LATE  
WEEK, THEN GRADUALLY MOVE EASTWARD AHEAD OF AN INCOMING TROUGH  
FROM THE PACIFIC TO THE WEST COAST. THIS PATTERN SHOULD PROMOTE  
GENERALLY DRY CONDITIONS ACROSS THE COUNTRY ASIDE FROM SOME EAST  
COAST PRECIPITATION EXITING THURSDAY-FRIDAY, SOME CLIPPER SYSTEMS  
IN THE GREAT LAKES REGION, AND INCREASING PRECIPITATION CHANCES IN  
THE WEST BY THE BEGINNING OF NEXT WEEK WITH THE TROUGH'S APPROACH.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
MODEL AGREEMENT FOR THE 12/18Z YESTERDAY CYCLE IS FAIRLY GOOD  
THROUGH THE LATTER PART OF THE WEEK, WITH GOOD CONSENSUS FOR A  
CLOSED UPPER LOW LINGERING INTO THURSDAY IN THE EAST-CENTRAL U.S.  
AND A SURFACE LOW IN THE GREAT LAKES REGION. GUIDANCE HAS  
CONTINUED A TREND TOWARD SLIGHTLY FASTER MOVEMENT OF THE LOW'S  
ASSOCIATED COLD FRONT ACROSS THE SOUTHEAST/FLORIDA BUT PERHAPS  
SLOWER FARTHER NORTH WITH THE OCCLUDED PART OF THE CYCLONE,  
LEADING TO A SLIGHT INCREASE IN PRECIPITATION IN THE NORTHEAST  
WITH THIS CYCLE. THERE WAS GOOD CONSENSUS IN THE 12/18Z GUIDANCE  
FOR ANOTHER SURFACE LOW TO DEVELOP NEAR THE NEW ENGLAND COAST BY  
FRIDAY MORNING PERHAPS AS A COMBINATION OF THE TRIPLE POINT LOW  
FROM THE ORIGINAL CYCLONE AND A WEAK LOW TRACKING NORTH ALONG THE  
COAST, BUT NEWER 00Z GUIDANCE IS NOT SO AGREEABLE, THOUGH THE 00Z  
EC IN PARTICULAR STILL INDICATES A SIMILAR SURFACE LOW. THIS  
INDICATES THE SPREAD STILL REMAINING IN THE TIMING AND ORIENTATION  
OF THE TROUGH AS IT LIFTS OUT FRIDAY. BUT THIS AS WELL AS  
ADDITIONAL ENERGY INCOMING BY SATURDAY SHOW AT LEAST A SIMILAR  
PATTERN WITH TYPICAL MEDIUM RANGE DIFFERENCES IN THE DETAILS. THUS  
THE EARLY PART OF THE WPC FORECAST WAS BASED ON A BLEND OF THE 12Z  
ECMWF, CMC, AND UKMET AND 18Z GFS, WITH THE BLEND TENDING TO  
SMOOTH OUT THE SMALLER MODEL VARIATIONS.  
 
MEANWHILE IN THE WEST, GUIDANCE AGREES THAT A RIDGE IN THE  
SOUTHWEST WILL BE INITIALLY SUPPRESSED IN THE NORTHWEST THURSDAY  
AS A SHORTWAVE TRACKS THROUGH. AFTER THAT, RIDGING SHOULD CONTINUE  
TO AMPLIFY OVER THE WEEKEND ACROSS THE INTERMOUNTAIN WEST AND  
ROCKIES, WITH GEFS MEMBERS GENERALLY ON THE MORE AMPLIFIED SIDE,  
WITH THE OPERATIONAL CMC ONE OF THE LESS AMPLIFIED MODELS. THIS IS  
ALSO RELATED TO GREATER DIFFERENCES WITH THE UPSTREAM TROUGH  
COMING IN FROM THE EAST PACIFIC. TIMING DIFFERENCES ABOUND WITH  
THE TROUGH, ALONG WITH DIFFERENCES WITH A POSSIBLE SOUTHERN STREAM  
LOW DEVELOPING AS FLOW SPLITS, WITH SOME GUIDANCE MORE PHASED THAN  
OTHERS AT TIMES. FOR THE WPC FORECAST, TENDED TOWARD THE TROUGH  
AXIS OF THE ECMWF MEAN AND EC OPERATIONAL RUN. THIS APPEARED TO BE  
A MIDDLE GROUND BETWEEN THE SLOWER GFS/GEFS (THOUGH THE 18Z AND  
00Z GFS RUNS WERE FASTER THAN THE 12Z) AND THE FASTER CMC MEAN.  
HOWEVER, VARYING ENSEMBLE MEMBERS AND RUN TO RUN MODEL DIFFERENCES  
INDICATE THAT FURTHER CHANGES ARE LIKELY TO THE FORECAST IN THIS  
AREA.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
AN OCCLUDED LOW PRESSURE SYSTEM WILL BE IN PLACE OVER THE UPPER  
GREAT LAKES EARLY THURSDAY, WITH LINGERING LIGHT PRECIPITATION  
THERE BUT WITH HEAVIER AMOUNTS POSSIBLE ALONG ITS ASSOCIATED COLD  
FRONT NEAR THE EAST COAST. MAINLY RAIN IS EXPECTED, BUT SNOW IS  
FORECAST FOR NORTHERN NEW ENGLAND, WHICH COULD LINGER ON FRIDAY IN  
MAINE NEAR A DEVELOPING COASTAL LOW. SHORTWAVE ENERGY AND WEAK LOW  
PRESSURE/FRONTAL SYSTEMS COULD LEAD TO LIGHT PRECIPITATION  
SPREADING FROM THE NORTHERN ROCKIES/PLAINS THURSDAY INTO THE GREAT  
LAKES REGION TO THE CENTRAL/NORTHERN APPALACHIANS AND NORTHEAST  
LATE WEEK INTO THE WEEKEND. LIGHT PRECIPITATION IN THE PACIFIC  
NORTHWEST IS POSSIBLE THROUGH THE LATTER PART OF THE WEEK, BUT  
PRECIPITATION CHANCES SHOULD INCREASE AND SPREAD INLAND ACROSS THE  
WEST BY AROUND SUNDAY, BUT WITH SOME DIFFERENCES IN TIMING AND  
MAGNITUDES AT THIS POINT.  
 
WARM TEMPERATURES WILL BUILD AND EXPAND UNDERNEATH UPPER RIDGING  
FROM THE WESTERN U.S. INTO THE PLAINS. HIGHS ARE FORECAST TO BE  
AROUND 10-20F ABOVE NORMAL FOR CALIFORNIA AND THE CENTRAL GREAT  
BASIN/SOUTHWEST THURSDAY AND FRIDAY, WITH 20+ ANOMALIES BUILDING  
IN THE GREAT BASIN SATURDAY AND SHIFTING TO THE NORTHERN/CENTRAL  
HIGH PLAINS EARLY NEXT WEEK AS THE RIDGE AXIS SHIFTS. DAILY RECORD  
TEMPERATURES COULD BE TIED OR SET ACROSS CALIFORNIA AND EASTWARD.  
MEANWHILE, COOLER AIR UNDERNEATH THE UPPER TROUGH/LOW IN THE  
CENTRAL U.S. SHOULD MODERATE AS IT MOVES EASTWARD, WITH  
TEMPERATURES GENERALLY 10F OR LESS BELOW NORMAL. HOWEVER,  
ADDITIONAL COLD FRONTS AND UPPER ENERGY WILL BRING BELOW NORMAL  
TEMPERATURES TO PARTS OF THE EASTERN THIRD OF THE U.S. BY SUNDAY,  
WITH THE GREAT LAKES SEEING 10-15F BELOW NORMAL HIGHS.  
 
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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