296  
FXUS02 KWBC 230659  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
258 AM EDT WED MAR 23 2022  
 
VALID 12Z SAT MAR 26 2022 - 12Z WED MAR 30 2022  
   
..OVERVIEW
 
 
OVER THE WEEKEND, TROUGHING WILL BE PRESENT ACROSS THE EASTERN  
U.S. WHILE PERIODIC SHORTWAVES AND FRONTS CAUSE LIGHT  
PRECIPITATION AND COOL TEMPERATURES FROM THE GREAT LAKES TO  
NORTHEAST. MEANWHILE A RIDGE CAUSING POTENTIALLY RECORD WARMTH  
WILL SHIFT FROM THE INTERMOUNTAIN WEST SLOWLY EASTWARD INTO THE  
HIGH PLAINS AHEAD OF ANOTHER TROUGH/UPPER LOW ENTERING THE WEST  
FROM THE EASTERN PACIFIC. WHILE THERE REMAIN SOME TIMING  
DIFFERENCES WITH THE TROUGH/LOW, WHEN IT ENTERS THE COUNTRY IT  
SHOULD COOL DOWN THE WEST AND INCREASE PRECIPITATION CHANCES. BY  
TUESDAY/WEDNESDAY, THERE IS DECENT AGREEMENT FOR A SURFACE LOW  
PRESSURE SYSTEM TO DEVELOP IN THE CENTRAL PLAINS, LEADING TO  
WETTER CONDITIONS ACROSS THE CENTRAL U.S. AND POTENTIALLY SOME  
SPRINGTIME SNOW FOR THE MIDWEST/GREAT LAKES.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
RECENT MODEL GUIDANCE SHOWS FAIRLY GOOD AGREEMENT FOR THE EARLY  
PART OF THE MEDIUM RANGE PERIOD OVER THE WEEKEND WITH THE INITIAL  
WESTERN RIDGE/EASTERN TROUGH PATTERN. SHORTWAVE ENERGY EMBEDDED  
WITHIN THE TROUGH SHOWS MINOR VARIATIONS AMONG MODELS, BUT WITH  
THE GENERAL IDEA THAT THE SHORTWAVE/CLIPPER WILL TRACK FROM THE  
GREAT LAKES SATURDAY TO THE EAST SUNDAY AND POSSIBLY INDUCE MODEST  
CYCLOGENESIS JUST OFF THE NEW ENGLAND COAST. THOUGH DETERMINISTIC  
MODELS VARY WITH THE EXACT POSITIONING OF THE LOW, ENSEMBLE  
MEMBERS AND MEANS INDICATE THIS POTENTIAL, AND THE DIFFERENCES ARE  
WITHIN TYPICAL SPREAD FOR A MEDIUM RANGE FORECAST.  
 
GREATER MODEL DIFFERENCES ARISE WITH THE EASTERN PACIFIC UPPER  
TROUGH. RECENT MODEL GUIDANCE HAS AT LEAST CONVERGED ON INDICATING  
A CLOSED LOW ON THE SOUTHERN END OF THE TROUGH JUST WEST OF  
CALIFORNIA EARLY NEXT WEEK, WHEREAS MODELS WERE MORE MIXED ON A  
CLOSED/OPEN SOLUTION OVER THE PAST COUPLE OF DAYS. THIS HAS LED TO  
A SLOWER TREND WITH THE INCOMING TROUGH/LOW OVERALL, THOUGH THE  
PAST 3 OR 4 ECMWF DETERMINISTIC RUNS HAVE BEEN THE EXCEPTIONALLY  
SLOW SOLUTIONS COMPARED TO OTHER GUIDANCE. BY LATE MONDAY INTO  
TUESDAY, GUIDANCE VARIES WITH THE HANDLING OF THE UPPER LOW  
POTENTIALLY PHASING BACK WITH THE NORTHERN STREAM AS ADDITIONAL  
SHORTWAVE ENERGY IN THE NORTHERN STREAM MAY INTERACT WITH IT. IN  
THE 12/18Z YESTERDAY MODEL CYCLE, THE ECMWF SHOWED NO PHASING  
BETWEEN THE FEATURES AS THE SOUTHERN STREAM LOW WAS FARTHER WEST  
AND THE SHORTWAVE FARTHER EAST, MISSING EACH OTHER. THE 12Z GFS  
WAS PHASED BY TUESDAY WITH THE 18Z GFS PHASED BY WEDNESDAY, WHILE  
THE CMC SHOWED SOME SEPARATION. THUS THERE ARE AMPLE TIMING  
DIFFERENCES WITH THE FEATURE AND ENSEMBLE MEMBERS SHOW  
CONSIDERABLE VARIABILITY AS WELL. REGARDLESS OF THESE DIFFERENCES,  
MOST MODELS/ENSEMBLES SHOW A DEVELOPING SURFACE LOW IN THE PLAINS  
BY TUESDAY/WEDNESDAY.  
 
THUS THE WPC MEDIUM RANGE FORECAST UTILIZED A MULTI-MODEL  
DETERMINISTIC BLEND FOR THE EARLY PART OF THE PERIOD, BUT WITH  
INCREASING PROPORTIONS OF THE SOMEWHAT BETTER CLUSTERED GEFS AND  
EC ENSEMBLE MEANS BY THE LATTER PART OF THE PERIOD GIVEN THE  
OPERATIONAL MODEL DIFFERENCES. OVERALL THE TRACK OF THE WESTERN  
LOW/TROUGH WAS A BIT SLOWER THAN CONTINUITY BUT NOT NEARLY AS SLOW  
AS THE DETERMINISTIC ECMWF RUNS.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
SHORTWAVE ENERGY AND WEAK LOW PRESSURE/FRONTAL SYSTEMS ARE  
EXPECTED TO PRODUCE LIGHT PRECIPITATION AS THEY MOVE ACROSS THE  
GREAT LAKES REGION TO THE CENTRAL/NORTHERN APPALACHIANS AND  
NORTHEAST OVER THE WEEKEND. SOME OF THE PRECIPITATION WILL BE IN  
THE FORM OF SNOW IN HIGHER ELEVATIONS (WEST VIRGINIA IN  
PARTICULAR) AND NEAR THE CANADIAN BORDER, FOLLOWED BY STRONG AND  
GUSTY WINDS WITH FALLING TEMPERATURES. PRECIPITATION AHEAD OF THE  
APPROACHING EASTERN PACIFIC UPPER TROUGH COULD AFFECT THE PACIFIC  
NORTHWEST SATURDAY WITH LIGHT AMOUNTS, BUT SPREAD FARTHER SOUTH TO  
CALIFORNIA AND EAST INTO THE ROCKIES AND INTERMOUNTAIN WEST EARLY  
NEXT WEEK. MOST OF THIS ACTIVITY SHOULD BE IN THE LIGHT TO  
MODERATE RANGE BUT SOME LOCALLY HEAVIER TOTALS ARE POSSIBLE,  
PARTICULARLY IN HIGHER ELEVATIONS WHERE UPSLOPE FLOW COULD ENHANCE  
AMOUNTS. RAIN CHANCES COULD INCREASE IN THE SOUTH-CENTRAL U.S. BY  
TUESDAY AHEAD OF LOW PRESSURE FORMING. MEANWHILE FARTHER NORTH,  
PRECIPITATION INCLUDING SOME SNOW/WINTRY WEATHER COULD AFFECT THE  
MIDWEST AND GREAT LAKES REGION, BUT WITH CONSIDERABLE UNCERTAINTY  
IN THE DETAILS.  
 
UNSEASONABLY WARM TEMPERATURES WILL BUILD AND EXPAND UNDERNEATH  
UPPER RIDGING FROM THE WESTERN U.S. INTO THE PLAINS. HIGHS THAT  
ARE 10-25F ABOVE NORMAL WILL BE COMMON OVER THE WEEKEND FROM THE  
WEST COAST ACROSS THE GREAT BASIN AND SOUTHWEST TO THE PLAINS, AND  
SEVERAL DAILY RECORD HIGH TEMPERATURES COULD BE SET OR TIED. AS  
THE RIDGE AXIS SHIFTS EASTWARD, WARM ANOMALIES OF 15-25F ARE  
LIKELY FOR THE HIGH PLAINS MONDAY WHILE THE WEST COAST MODERATES  
CLOSER TO NORMAL. WARMER THAN NORMAL TEMPERATURES REMAIN FORECAST  
IN THE SOUTH-CENTRAL U.S. ON TUESDAY BUT MAY MODERATE WEDNESDAY  
WHILE PUSHING INTO THE SOUTHEAST. MEANWHILE THE EAST SHOULD SEE  
NEAR TO BELOW AVERAGE TEMPERATURES GIVEN MEAN UPPER TROUGHING,  
WITH COOLEST TEMPERATURES OF 10-20F BELOW NORMAL IN THE GREAT  
LAKES AND CENTRAL APPALACHIANS FOR THE WEEKEND AND SPREADING INTO  
THE NORTHEAST EARLY NEXT WEEK.  
 
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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