127  
FXUS02 KWBC 261833  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
132 PM 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
 
 
OVERALL, THE LATEST 00Z/06Z SUITE OF MODELS AND ENSEMBLES  
CONTINUED TO BE RELATIVELY AGREEABLE ON THE LARGE SCALE FLOW  
EVOLUTION DURING THE MEDIUM RANGE PERIOD. THERE REMAINS SOME  
QUESTIONS ON TIMING OF A FEW CLIPPER SYSTEMS WITHIN THE BROADER  
EASTERN U.S. TROUGH. BIGGER UNCERTAINTIES LIE WITH A COUPLE OF  
INCOMING SHORTWAVES INTO THE WEST AND THEN HOW THAT TROUGH OPENS  
AND BROADENS OVER THE WEST LATE PERIOD. THE 00Z ECMWF IS A HAIR  
FASTER WITH AN INITIAL SHORTWAVE INTO THE PACIFIC NORTHWEST ON  
THURSDAY (AND ALSO LATE PERIOD WITH DEVELOPING LOW PRESSURE OVER  
THE PLAINS), WHILE THE CMC IS MORE AMPLIFIED. MORE UNCERTAINTY  
UPSTREAM FROM THIS INITIAL WAVE ARISE, MAINLY IN THE DETAILS OF  
POSSIBLE COMPACT AND EMBEDDED CLOSED LOWS AND TIMING. IN GENERAL,  
THE 06Z GFS SEEMED TO BE THE MOST STABLE AND AGREEABLE TO THE  
ENSEMBLE MEANS AS THE MEAN TROUGH COMES INTO PLAY ACROSS THE WEST.  
 
THE WPC BLEND FOR TODAYS UPDATED PROGS USED A MULTI-MODEL  
DETERMINISTIC BLEND FOR DAYS 3-4, SLOWLY INCREASING CONTRIBUTION  
FROM THE ENSEMBLE MEANS LATER IN THE PERIOD. WAS ABLE TO MAINTAIN  
60 PERCENT DETERMINISTIC EVEN OUT TO DAY 7, THOUGH WITH MORE  
WEIGHTING ON THE GFS COMPARED TO THE ECMWF AND CMC. THIS APPROACH  
HELPS TO MITIGATE THE HARDER TO RESOLVE SMALL SCALE DIFFERENCES  
AND MAINTAINS GOOD CONTINUITY FROM THE PREVIOUS WPC FORECAST.  
   
..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.  
 
SANTORELLI/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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