981  
FXUS02 KWBC 260659  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
158 AM EST SAT FEB 26 2022  
 
VALID 12Z TUE MAR 01 2022 - 12Z SAT MAR 05 2022  
   
..OVERVIEW
 
 
LATEST GUIDANCE CONTINUES TO SHOW AN UPPER PATTERN CONSISTING OF A  
WESTERN RIDGE AND BROAD EASTERN MEAN TROUGH THROUGH MIDWEEK,  
FOLLOWED BY A TRANSITION TOWARD A MEAN TROUGH SETTLING INTO THE  
WESTERN U.S. WHILE UPPER HEIGHTS RISE FARTHER TO THE EAST. THE  
PRIMARY PRECIPITATION FOCUS EARLY IN THE PERIOD WILL BE OVER THE  
PACIFIC NORTHWEST AND NORTHERN ROCKIES AHEAD OF THE EASTERN  
PACIFIC TROUGH THAT EVENTUALLY MOVES INTO THE WEST. PROGRESSION  
OF THIS TROUGH LATER IN THE WEEK INTO NEXT WEEKEND WILL SPREAD  
PRECIPITATION OVER OTHER PARTS OF THE WEST AND THEN BRING A  
VARIETY OF PRECIPITATION TYPES TO THE CENTRAL U.S. AS LOW PRESSURE  
EMERGES OVER THE PLAINS. AHEAD OF THIS SYSTEM, EXPECT MOST  
PRECIPITATION EAST OF THE ROCKIES TO BE CONFINED TO A COUPLE  
EPISODES OF SNOW ACROSS NORTHERN AREAS WITH ASSOCIATED SURFACE  
WAVES. THE PATTERN EVOLUTION WILL FAVOR ABOVE NORMAL TEMPERATURES  
OVER A MAJORITY OF THE WESTERN/CENTRAL U.S. THROUGH WEDNESDAY OR  
THURSDAY AND THEN A COOLER TREND OVER THE WEST AND WARMER READINGS  
OVER THE EAST.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
TWO DOMINANT UNCERTAINTIES REMAIN WITHIN WHAT CONTINUES TO BE AN  
AGREEABLY DEPICTED MEAN PATTERN EVOLUTION THROUGH THE PERIOD. THE  
FIRST INVOLVES THE EAST-WEST SHORTWAVE ENERGY FORECAST TO BE OVER  
CENTRAL CANADA ON TUESDAY AND THEN DROP INTO THE CYCLONIC FLOW  
DOWNSTREAM, WITH TUESDAY-THURSDAY SURFACE LOW PRESSURE AND FRONTAL  
SYSTEM VERY SENSITIVE TO THE EXACT DETAILS OF THE ENERGY ALOFT.  
THE UPPER FEATURE IS SOUTH/SOUTHEAST OF A CLOSED HIGH AND SUCH A  
CONFIGURATION TENDS TO YIELD LOW PREDICTABILITY, WITH  
MODEL/ENSEMBLE SPREAD DEMONSTRATING THIS IDEA SO FAR. IN LATEST  
CYCLES THE ECMWF/GFS HAVE TENDED TO BE MOST SHEARED WITH THE  
SHORTWAVE ENERGY AND THUS WEAK WITH LOW PRESSURE, WHILE THE  
UKMET/CMC'S MORE CONCENTRATED DEPICTION OF ENERGY ALOFT RESULTS IN  
A STRONGER SURFACE SYSTEM. ENSEMBLE MEANS GENERALLY REFLECT THE  
IDEAS OF THEIR PARENT MODELS. FOR NOW THE PREFERENCE LEANS ON THE  
WEAKER SIDE TO MAINTAIN BETTER CONTINUITY UNTIL THERE IS REASON TO  
BE MORE CONFIDENT IN THE ALTERNATIVE. THE SECOND UNCERTAINTY  
INVOLVES THE UPPER TROUGH MOVING INTO THE WEST BY THURSDAY. THERE  
HAS BEEN PROGRESS TOWARD BETTER AGREEMENT TO SOME DEGREE, AS  
LATEST GFS RUNS HAVE STABILIZED TOWARD A FAIRLY AMPLIFIED TROUGH  
THAT HAD BEEN ADVERTISED BY MOST OTHER GUIDANCE. THE CMC IS STILL  
A LITTLE QUESTIONABLE AS IT IS MORE AMPLIFIED THAN MOST OTHER  
SOLUTIONS AT SOME VALID TIMES AND THE NEW 00Z RUN HAS AN EXTRA  
EMBEDDED LOW WITHIN THE TROUGH AS IT COMES ASHORE. THE CHARACTER  
OF UPSTREAM SMALL-SCALE ENERGY DROPPING INTO THE OVERALL TROUGH  
(00Z CMC AN AMPLIFIED EXTREME) STILL COMPLICATES THE FORECAST.  
THE 12Z ECMWF WAS REASONABLE FOR THIS FEATURE BUT STILL STRAYED ON  
THE FAST SIDE WITH THE CENTRAL U.S. DYNAMICS AND SURFACE SYSTEM BY  
NEXT SATURDAY--DUE IN PART TO BEING QUICKER TO LIFT OUT EASTERN  
TROUGHING.  
 
FOR THE UPDATED FORECAST, GUIDANCE COMPARISONS LED TO AN  
OPERATIONAL MODEL EMPHASIS EARLY FOLLOWED BY PARTIAL INCORPORATION  
OF THE 18Z GEFS/12Z ECMWF MEANS. ECMWF INPUT CONSISTED OF BOTH  
THE 12Z RUN AND PRIOR 00Z VERSION THROUGH THE PERIOD DUE TO THE  
OLDER RUN HAVING SOME APPEALING TRAITS FOR BOTH SYSTEMS OF  
INTEREST. TWO-THIRDS TOTAL WEIGHT OF THE GFS/ECMWF INTO EARLY  
THURSDAY YIELDED THE DESIRED OUTCOME FOR THE EASTERN U.S. WAVE  
WHOSE CHARACTER REMAINS A SIGNIFICANT QUESTION MARK.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
MOIST FLOW AHEAD OF THE UPPER TROUGH INITIALLY OVER THE EASTERN  
PACIFIC SHOULD CONTINUE A PACIFIC NORTHWEST ATMOSPHERIC RIVER  
EVENT ALREADY IN PROGRESS AT THE START OF THE PERIOD EARLY  
TUESDAY. AMOUNTS DURING TUESDAY-WEDNESDAY SHOULD BE SOMEWHAT  
LOWER THAN IN THE SHORT RANGE AT THE START OF THE WEEK BUT COULD  
STILL BE MEANINGFUL AT SOME LOCATIONS. SOME OF THIS MOISTURE WILL  
EXTEND INTO THE NORTHERN ROCKIES. PROGRESSION OF THE UPPER TROUGH  
INTO THE WEST AFTER MIDWEEK SHOULD LEAD TO A LIGHTER TREND ALONG  
THE WEST COAST AND SPREAD PRECIPITATION INTO CENTRAL CALIFORNIA  
AND SOME OTHER PARTS OF THE WEST, MOSTLY WITH LIGHT TO MODERATE  
AMOUNTS OF RAIN AND HIGHER ELEVATION SNOW. EXPECT PRECIPITATION  
TO EXPAND ACROSS THE CENTRAL U.S. LATE WEEK INTO THE WEEKEND AS  
WESTERN TROUGH ENERGY REACHES FAR ENOUGH EAST TO SUPPORT PLAINS  
LOW PRESSURE. BEST POTENTIAL FOR SOME WINTRY WEATHER WILL BE OVER  
THE NORTHERN THIRD OF THE PLAINS INTO THE UPPER MIDWEST. AREAS  
FROM THE UPPER MIDWEST INTO NORTHEAST MAY SEE A COUPLE PERIODS OF  
SNOW TUESDAY-THURSDAY IN ASSOCIATION WITH CLIPPER SYSTEMS, THE  
FIRST ONE FAIRLY WELL FORECAST BUT THE SECOND HAVING MUCH GREATER  
UNCERTAINTY FOR STRENGTH/TRACK DETAILS. THUS CONFIDENCE IS A LOT  
LOWER FOR COVERAGE AND AMOUNTS OF SNOW WITH THE SECOND SYSTEM.  
 
ABOVE NORMAL TEMPERATURES WILL PREVAIL OVER A MAJORITY OF THE  
WESTERN AND CENTRAL U.S. TUESDAY-WEDNESDAY. PROGRESSION OF THE  
INITIAL EASTERN PACIFIC UPPER TROUGH WILL PROMOTE A COOLER TREND  
OVER THE WEST AFTER MIDWEEK AND THEN FAVOR NORTHWARD EXPANSION OF  
ABOVE NORMAL TEMPERATURES (PLUS 10-15F OR SO ANOMALIES) FROM THE  
SOUTH ACROSS A GREATER PORTION OF THE EASTERN U.S. PLUS 10-20F  
ANOMALIES WILL BE POSSIBLE FOR MAX AND/OR MIN TEMPERATURES FOR ONE  
OR MORE DAYS OVER THE GREAT BASIN/SOUTHWEST THROUGH MIDWEEK AND  
PARTS OF THE ROCKIES/PLAINS INTO LATER IN THE WEEK. CENTRAL  
PLAINS LOCATIONS COULD EXCEED PLUS 20F ANOMALIES FOR HIGHS. AREAS  
FROM THE UPPER MIDWEST TO THE NORTHEAST WILL TEND TO BE MODERATELY  
BELOW NORMAL AND COLDER AIR FILTERING INTO MONTANA/NORTH DAKOTA  
COULD BRING HIGHS DOWN TO 10-20F BELOW NORMAL BY NEXT SATURDAY.  
 
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, 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/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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