868  
FXUS02 KWBC 020700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 AM EST WED MAR 02 2022  
 
VALID 12Z SAT MAR 05 2022 - 12Z WED MAR 09 2022  
 
...HEAVY SNOW POTENTIAL OVER THE NORTHERN PLAINS THROUGH GREAT  
LAKES AND POSSIBLY INTO NORTHERN NEW ENGLAND DURING THE WEEKEND...  
 
...HEAVY RAINFALL POTENTIAL FROM THE MID-LOWER MISSISSIPPI VALLEY  
INTO TENNESSEE/OHIO VALLEYS LATE WEEKEND INTO EARLY NEXT WEEK...  
   
..OVERVIEW
 
 
GUIDANCE MAINTAINS THE FORECAST OF A POSITIVELY TILTED MEAN TROUGH  
FROM CANADA INTO THE WESTERN U.S., BETWEEN A STRONG RIDGE OVER THE  
EASTERN PACIFIC AND ANOTHER RIDGE RIDGE THAT MEANDERS OVER OR NEAR  
THE SOUTHEASTERN GULF OF MEXICO. THIS CONFIGURATION WILL SUPPORT  
AN ACTIVE WEATHER PATTERN, WITH A COUPLE EPISODES OF PRECIPITATION  
OVER PARTS OF THE WEST AND LIKELY ONE OR MORE AREAS OF SIGNIFICANT  
RAIN AND SNOW OVER SOME AREAS OF THE CENTRAL AND EASTERN U.S. THE  
SYSTEM HAVING HIGHEST CONFIDENCE WILL TRACK NORTHEASTWARD FROM THE  
CENTRAL ROCKIES/PLAINS INTO THE UPPER GREAT LAKES THIS WEEKEND  
WITH A CORRESPONDING BAND OF SNOW FROM THE NORTH-CENTRAL HIGH  
PLAINS THROUGH THE UPPER GREAT LAKES AND POSSIBLY NORTHERN NEW  
ENGLAND. A TRAILING UPPER LOW REACHING THE WEST SHOULD ULTIMATELY  
PRODUCE ANOTHER SURFACE WAVE, ALONG THE FIRST SYSTEM'S COLD FRONT,  
THAT TAKES A SOMEWHAT FARTHER SOUTHEAST TRACK BUT WHOSE DETAILS  
ARE OTHERWISE LESS CERTAIN. THIS EVOLUTION MAY SUPPORT AN AREA OF  
HEAVY RAINFALL OVER PARTS OF THE EAST-CENTRAL U.S. LATE WEEKEND  
INTO EARLY NEXT WEEK AND POSSIBLY SOME SNOW ON THE COLD SIDE OF  
THE SECOND WAVE. BELOW NORMAL TEMPERATURES INITIALLY OVER THE WEST  
AND NORTHERN PLAINS WILL EXPAND INTO THE REST OF THE CENTRAL U.S.  
WHILE FRONTAL PROGRESSION WILL GRADUALLY TRIM THE WESTERN EXTENT  
OF MUCH ABOVE NORMAL TEMPERATURE ANOMALIES OVER THE  
CENTRAL/EASTERN STATES.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
EARLY IN THE PERIOD A BLEND OF THE 12Z/18Z OPERATIONAL MODELS  
PROVIDED A REASONABLE STARTING POINT FOR THE FORECAST. AFTER SOME  
SIGNIFICANT VARIABILITY AND SPREAD IN RECENT DAYS, GUIDANCE OVER  
THE PAST DAY APPEARS TO BE STABILIZING WITHIN THE STRONGER HALF OF  
THE PRIOR ENVELOPE FOR STRENGTH AS IT REACHES THE UPPER GREAT  
LAKES EARLY SUNDAY WHILE MAINTAINING DECENT CONTINUITY FOR TRACK.  
THE 00Z CMC TRENDED SOMEWHAT WEAKER THAN ITS 12Z RUN THOUGH.  
LATEST CONSENSUS SEEMS TO BE HOLDING ONTO BETTER DEFINITION AS IT  
CONTINUES NORTHEASTWARD. THE TRAILING WAVE (OR EVEN TWO WAVES),  
INITIALLY SUPPORTED BY THE NEXT UPPER LOW TRACKING OUT OF THE  
WEST, STILL SHOWS UP IN MOST GUIDANCE BUT IT REMAINS A COMPLICATED  
FORECAST. NOT ONLY DOES FLOW IMMEDIATELY UPSTREAM HAVE SOME  
POSSIBLE INFLUENCE ON THE FEATURE, BUT SEPARATE UPPER TROUGHING  
THAT DROPS INTO THE NORTHERN PLAINS AND VICINITY COULD EVENTUALLY  
INTERACT WITH IT. THUS LATEST RUNS VARY SIGNIFICANTLY FOR THE  
CHARACTER AND TIMING OF THE SURFACE REFLECTION (NEW 00Z ECMWF  
TRENDING NOTABLY SLOWER FOR EXAMPLE), INCLUDING DIFFERENCES IN  
STRENGTH AND WHETHER THERE IS ONE CONSOLIDATED WAVE OR POSSIBLY  
TWO WAVES. BY EARLY MONDAY THE MODEL BLEND AND MODEST  
INCORPORATION OF THE 18Z GEFS/12Z ECMWF MEANS ACCOUNTED FOR THE  
UNCERTAINTY WITH THIS FEATURE AT THAT TIME. IF ANYTHING,  
NORTH-SOUTH SPREAD HAS WIDENED IN THE NEW 00Z GUIDANCE.  
 
RETURNING UPSTREAM LATER IN THE PERIOD, THERE IS SOME RELATIVE  
AGREEMENT THAT MID-PERIOD ENERGY OVER THE WEST SHOULD GRADUALLY  
CONTINUE EASTWARD (BUT WITH LESS EFFECT ON SENSIBLE WEATHER) BUT A  
LOT MORE SPREAD WITH A SHORTWAVE EXPECTED TO ROUND THE PACIFIC  
RIDGE AND POSSIBLY DROP INTO THE NORTHWEST. ENSEMBLE MEANS HAVE  
TENDED TO AGREE UPON A SOMEWHAT FASTER PROGRESSION THAN THE LATEST  
ECMWF AND ESPECIALLY CMC RUNS WHILE THE GFS AND UKMET HAVE BEEN  
CLOSER TO THE MEANS IN PRINCIPLE. FOR CONTINUITY THE FORECAST  
ULTIMATELY TRENDED A LITTLE MORE TOWARD THE ENSEMBLE MEANS BY NEXT  
WEDNESDAY WITH A LITTLE MORE WEIGHT TO THE GFS RELATIVE TO THE  
ECMWF FOR THE LINGERING OPERATIONAL WEIGHT.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
ACROSS THE WEST, THE LEADING SYSTEM EMERGING INTO THE PLAINS MAY  
PRODUCE SOME CENTRAL ROCKIES SNOW EARLY IN THE WEEKEND WHILE THE  
SYSTEM IMMEDIATELY BEHIND IT SPREADS RAIN AND HIGHER ELEVATION  
SNOW PRIMARILY FROM THE SIERRA NEVADA INTO THE WASATCH AND CENTRAL  
ROCKIES. EXPECT GENERALLY LIGHT TO MODERATE TOTALS BUT WITH SOME  
LOCALLY HEAVIER TOTALS POSSIBLE. THERE IS CONTINUED POTENTIAL FOR  
ANOTHER SYSTEM TO SPREAD MOSTLY LIGHT TO MODERATE PRECIPITATION  
INTO THE NORTHWEST/NORTHERN ROCKIES DURING THE FIRST HALF OF NEXT  
WEEK BUT WITH LESS THAN IDEAL CONFIDENCE IN THE DETAILS.  
 
TO THE EAST OF THE ROCKIES, THE LEADING SYSTEM FORECAST TO TRACK  
FROM THE CENTRAL PLAINS THROUGH UPPER GREAT LAKES DURING THE  
WEEKEND SHOULD SPREAD WINTRY PRECIPITATION FROM THE NORTH-CENTRAL  
HIGH PLAINS INTO THE UPPER GREAT LAKES AND EVENTUALLY NEW ENGLAND  
(WHERE A CHANGEOVER TO RAIN MAY OCCUR). HIGHEST PROBABILITY OF  
SIGNIFICANT SNOWFALL REMAINS JUST TO THE NORTHWEST OF THE SURFACE  
LOW TRACK, WITH INCREASING CHANCES OVER THE NORTHERN PLAINS AND  
CONTINUED CHANCES OVER THE UPPER MIDWEST. THE STORM MAY BE STRONG  
ENOUGH TO PRODUCE SOME BRISK WINDS, WITH SPECIFICS TO BE RESOLVED  
IN COMING DAYS. RAINFALL OF VARYING INTENSITY WILL BE POSSIBLE  
OVER THE REST OF THE CENTRAL/EAST-CENTRAL U.S. AHEAD OF THE  
TRAILING COLD FRONT. EMBEDDED THUNDERSTORMS COULD BE SEVERE IN THE  
MID-MISSISSIPPI VALLEY ON SATURDAY PER THE LATEST STORM PREDICTION  
CENTER EXTENDED OUTLOOK. GUIDANCE IS STILL SHOWING POTENTIAL FOR  
HEAVIER RAINFALL WITHIN AN AREA FROM THE SOUTHEASTERN PLAINS INTO  
THE OHIO/TENNESSEE VALLEYS BY SATURDAY NIGHT/SUNDAY INTO EARLY  
NEXT WEEK. THIS THREAT CORRESPONDS TO SLOWER PROGRESSION OF THE  
TRAILING FRONT AS IT BECOMES MORE ALIGNED WITH FLOW ALOFT,  
INTERACTION WITH LOW LEVEL GULF MOISTURE, AND THE POSSIBILITY OF  
ONE OR MORE WAVES THAT WOULD PROVIDE ADDED RAINFALL FOCUS. THE  
NORTHWESTERN FRINGE OF THIS MOISTURE SHIELD SHOULD CONTAIN SOME  
WINTRY WEATHER, LIKELY ALONG AN AXIS SOMEWHAT SOUTHEAST OF THE  
FIRST EPISODE. SPECIFICS WILL DEPEND ON LOWER-CONFIDENCE WAVE  
DETAILS WHICH WILL TAKE ADDITIONAL TIME TO RESOLVE.  
 
COLDER AIR INITIALLY OVER THE WESTERN U.S. AND NORTHERN PLAINS AND  
SPREADING OVER THE REST OF THE CENTRAL U.S. INTO EARLY NEXT WEEK  
SHOULD YIELD A BROAD AREA OF TEMPERATURES THAT ARE 5-15F BELOW  
NORMAL. BEST POTENTIAL FOR LOCALLY COLDER ANOMALIES, ESPECIALLY  
FOR HIGHS, WILL BE OVER THE NORTHERN/CENTRAL HIGH PLAINS. LEADING  
WARM SECTOR AIR, INITIALLY FOCUSED OVER THE CENTRAL-SOUTHERN  
PLAINS AND SOUTHERN TWO-THIRDS OF THE EAST ON SATURDAY, WILL  
BECOME MORE PRONOUNCED OVER THE EAST BY SUNDAY-MONDAY WHEN PLUS  
10-25F ABOVE NORMAL ANOMALIES FOR HIGHS AND LOCALIZED HIGHER  
ANOMALIES FOR MORNING LOWS MAY CHALLENGE DAILY RECORDS FOR  
HIGHS/WARM LOWS. HIGHEST CONCENTRATION OF RECORD HIGHS MAY BE OVER  
THE SOUTHEAST WITH A FEW RECORD HIGHS ELSEWHERE. COVERAGE OF  
RECORD WARM LOWS MAY BE BROADER. AFTER MONDAY, FRONTAL PROGRESSION  
WILL INCREASINGLY CONFINE THE WARMTH TO THE SOUTHEAST.  
 
RAUSCH/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  
 
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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