933  
FXUS02 KWBC 131900  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
159 PM EST SUN FEB 13 2022  
 
VALID 12Z WED FEB 16 2022 - 12Z SUN FEB 20 2022  
 
...MID-LATE WEEK SYSTEM TO BRING POTENTIAL FOR HEAVY RAIN AND  
SEVERE WEATHER FROM THE SOUTH-CENTRAL TO EASTERN U.S. AND WINTRY  
WEATHER FROM THE MIDWEST THROUGH GREAT LAKES AND INTERIOR  
NORTHEAST...  
   
..OVERVIEW
 
 
AN UPPER TROUGH/LOW THAT IS LIKELY TO BE CENTERED NEAR THE FOUR  
CORNERS EARLY WEDNESDAY AND THEN PHASE WITH A PLAINS/EAST-CENTRAL  
U.S. MEAN TROUGH AS IT CONTINUES EASTWARD WILL BE PRODUCE THE MOST  
ACTIVE WEATHER OVER THE LOWER 48 DURING THE FORECAST PERIOD. THE  
EJECTING UPPER SYSTEM WILL LEAD TO SURFACE CYCLOGENESIS AND STRONG  
FRONTAL SYSTEMS IN THE CENTRAL U.S., DRAWING MOISTURE NORTHWARD  
FROM THE GULF OF MEXICO AND PRODUCING NOTABLE PRECIPITATION FROM  
THE PLAINS EASTWARD NEXT WEDNESDAY AND THURSDAY. EXPECT RAIN AND  
THUNDERSTORMS IN SOUTHERN AREAS, WHILE SNOW AND WINTRY WEATHER ARE  
LIKELY ON THE NORTHERN AND WESTERN SIDE OF THE PRECIPITATION  
SHIELD ACROSS THE CENTRAL ROCKIES/PLAINS AND THROUGH THE MIDWEST,  
GREAT LAKES, AND INTERIOR NORTHEAST. THERE IS STILL UNCERTAINTY IN  
THE PRECISE AXIS OF MEANINGFUL SNOW THOUGH. BY FRIDAY-SATURDAY  
EXPECT A CLIPPER SYSTEM TRACKING NEAR THE CANADIAN BORDER TO BRING  
A COLD FRONT INTO THE NORTHERN TIER AND SOME SNOW INTO THE GREAT  
LAKES WHILE A STEADILY WEAKENING (BUT INITIALLY QUITE STRONG)  
EASTERN PACIFIC UPPER RIDGE DRIFTS TOWARD THE WEST COAST. ANOTHER  
PACIFIC UPPER TROUGH WITH LEADING FRONTAL SYSTEM MAY REACH THE  
WEST COAST BY SUNDAY.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE AGREEMENT IN THE OVERALL PATTERN AND THE FORECAST PHILOSOPHY  
IN RESPONSE TO GUIDANCE BEHAVIOR REMAINS FAIRLY CONSISTENT. THE  
MULTI-DAY TREND HAS BEEN WEAKER/FASTER FOR THE PLAINS THROUGH  
EASTERN GREAT LAKES EVOLUTION OF THE SYSTEM AFFECTING THE  
CENTRAL/EASTERN U.S. MID-LATE WEEK, BUT WITH GOOD CONTINUITY FOR  
INTENSIFICATION FROM THE EASTERN GREAT LAKES ONWARD IN RESPONSE TO  
NORTHERN STREAM DYNAMICS. CMC RUNS HAVE BEEN PERSISTENTLY  
DIFFERENT FROM THE MAJORITY CLUSTER--TENDING TO BE WEAKER AND MORE  
SHEARED BUT LATELY SHOWING IMPROVED DEFINITION FOR LOW PRESSURE  
OVER THE EASTERN HALF OF THE COUNTRY ALBEIT WITH A MORE SOUTHERN  
TRACK. THE GFS HAS ACTUALLY TRENDED A BIT STRONGER WITH ITS  
SURFACE LOW OVER THE PAST 12 HOURS OF RUNS THROUGH THE 12Z CYCLE  
AND THE CONSENSUS AVERAGE HAS NUDGED A FRACTION WEST WITH ITS  
PRECIP SHIELD VERSUS PREVIOUS CYCLE. THUS IT IS HOPED THAT  
GUIDANCE MAY BE STARTING TO STABILIZE BETTER AROUND A MIDPOINT  
EVEN WITH SOME SHUFFLING OF INDIVIDUAL RUNS IN RESPONSE TO  
LINGERING DIFFERENCES IN DETAILS OF NORTHERN STREAM FLOW AND  
ENERGY REACHING THE WESTERN U.S. A COMPOSITE OF THE 06Z GFS AND  
00Z ECMWF/UKMET CONTINUED TO PROVIDE THE BEST TEMPLATE FOR THE  
EVOLUTION OF THIS SYSTEM, WITH ONLY MODEST NUDGES FROM CONTINUITY.  
 
AS FOR THE REST OF THE FORECAST, CLUSTERING STILL LOOKS BETTER  
THAN AVERAGE FOR THE SYSTEM EXPECTED TO TRACK NEAR THE CANADIAN  
BORDER AROUND FRIDAY-SATURDAY IN RESPONSE TO STRONG WESTERN CANADA  
FLOW SETTLING INTO THE EAST-CENTRAL NORTH AMERICA MEAN TROUGH.  
SPREAD/VARIABILITY WITH EXACT AMPLITUDE OF THE RESULTING UPPER  
TROUGH LEAD TO SOME DIFFERENCES WITH THE TIMING AND SOUTHWARD  
EXTENT OF THE TRAILING FRONT REACHING INTO THE CENTRAL AND EASTERN  
U.S. NOTICEABLE DIFFERENCES EXIST FOR THE PACIFIC TROUGH  
APPROACHING THE WEST COAST. GFS RUNS HAVE VARIED WITHIN THE MIDDLE  
TO SLOWER PART OF THE ENVELOPE, WITH THE NEW 12Z RUN BEING ONE OF  
THE SLOWER VERSIONS. ECMWF RUNS HAVE BEEN FAIRLY STABLE IN THE  
MIDDLE SO FAR, WHILE THE 00Z CMC WAS A BIT FAST BUT ADJUSTED BACK  
SOME IN THE 12Z CYCLE. LATEST GEFS MEANS ARE SLOWER THAN THE 00Z  
ECMWF MEAN BUT NOT AS SLOW AS THE 12Z GFS. SOME OF THE SPREAD FOR  
THIS TROUGH MAY BE DUE TO UNCERTAINTY OVER HOW MUCH IF ANY ENERGY  
MAY SEPARATE FROM THE SOUTHERN PART OF THE FEATURE FARTHER  
UPSTREAM (AS SEEN IN 00Z AND NEW 12Z ECMWF DIFFERENCES). A WEAK  
SHORTWAVE THAT MAY DROP INTO THE WEST AHEAD OF THIS TROUGH IS  
RATHER SMALL IN SCALE AND HAS BELOW AVERAGE PREDICTABILITY, WITH  
LOW CONFIDENCE IN A SPECIFIC SOLUTION.  
 
THIS CYCLE'S FORECAST CONSIDERATIONS LED TO A STARTING BLEND  
CONSISTING OF THE 18Z GFS/12Z ECMWF/12Z UKMET FOR THE FIRST HALF  
OF THE PERIOD, FOLLOWED BY SOME INCLUSION OF THE 06Z GEFS/00Z  
ECMWF MEANS ALONG WITH THE 06Z GFS/00Z ECMWF.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
SHOWERS AND THUNDERSTORMS WILL BECOME WIDESPREAD OVER THE CENTRAL  
U.S. ON WEDNESDAY INTO THURSDAY AS SURFACE LOW PRESSURE  
CONSOLIDATES IN THE HIGH PLAINS AND ADVECTS SUBSTANTIAL MOISTURE  
FROM THE GULF OF MEXICO NORTHWARD INTO THE PLAINS,  
MISSISSIPPI/TENNESSEE/OHIO VALLEYS, AND EVENTUALLY THE  
APPALACHIANS AND EASTERN SEABOARD. STRONG STORMS ARE POSSIBLE,  
WITH THE STORM PREDICTION CENTER OUTLOOK SHOWING SOME SEVERE  
THREAT FOR PARTS OF THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI  
AND TENNESSEE VALLEYS AND VICINITY ON WEDNESDAY AND THURSDAY.  
THERE COULD ALSO BE FLASH FLOODING CONCERNS WHERE HEAVY RAINFALL  
OCCURS, POSSIBLY IN SIMILAR REGIONS AND SPREADING TOWARD MUCH OF  
THE EASTERN SEABOARD ON THURSDAY AND THURSDAY NIGHT. CURRENT  
FORECASTS SHOW THE SOUTHERN APPALACHIANS COULD SEE PARTICULARLY  
HIGH RAINFALL TOTALS GIVEN TERRAIN ENHANCEMENT THERE. CONTINUE TO  
MONITOR FORECASTS AS UNCERTAIN DETAILS OF THESE POTENTIAL THREATS  
BECOME BETTER REFINED. AT THE SAME TIME, EXPECT A BAND OF SNOW IN  
THE COLDER AIR ON THE NORTHWESTERN PERIPHERY OF THE SYSTEM. THE  
BEST POTENTIAL FOR MEANINGFUL ACCUMULATIONS CURRENTLY EXTENDS FROM  
CENTRAL PARTS OF THE PLAINS AND MIDWEST/MIDDLE MISSISSIPPI VALLEY  
INTO THE GREAT LAKES REGION AND INTERIOR NEW ENGLAND, WHILE MIXED  
PRECIPITATION/ICE CANNOT BE RULED OUT IN THE TRANSITION ZONE  
BETWEEN THE SNOW AND RAIN. TOTALS/LOCATION OF ANY SNOW WILL BE  
VERY SENSITIVE TO PRECISE STRENGTH AND TRACK OF THE SYSTEM GIVEN  
THAT WINTRY WEATHER COULD BE WITHIN A FAIRLY NARROW BAND.  
PROBABILISTIC FORECASTS OF 0.25 INCH LIQUID IN THE FORM OF SNOW  
REFLECT THE UNCERTAINTY IN THIS ASPECT OF THE FORECAST, WITH  
VALUES GENERALLY BELOW 50 PERCENT FOR ANY PARTICULAR LOCATION BUT  
WITH A DECENT SIGNAL THAT THERE SHOULD BE A BAND OF ENHANCED SNOW  
SOMEWHERE WITHIN THE FAVORED ZONE. GUSTY WINDS ARE POSSIBLE WITH  
THE SYSTEM AS WELL, AND AT THIS POINT APPEAR MOST LIKELY NEAR THE  
NORTHEAST COAST ON THURSDAY NIGHT IN STRONG SOUTHERLY FLOW AHEAD  
OF THE QUICKLY STRENGTHENING SURFACE LOW.  
 
DRY CONDITIONS SHOULD PREVAIL OVER MUCH OF THE LOWER 48 BEHIND  
THIS SYSTEM. BY FRIDAY OR SATURDAY THE SYSTEM ALONG THE CANADIAN  
BORDER MAY BRING SOME SNOW INTO THE UPPER GREAT LAKES WHILE LIGHT  
PRECIPITATION MAY REACH THE NORTHERN PACIFIC NORTHWEST/ROCKIES BY  
FRIDAY, WITH LIGHT TO LOCALLY MODERATE PRECIPITATION SPREADING  
SOUTHEASTWARD FARTHER INTO THE WEST BY SUNDAY. SOME MOISTURE MAY  
LINGER OVER THE FAR SOUTHEAST/FLORIDA. CONFIDENCE IN COVERAGE AND  
INTENSITY OF RAINFALL IS STILL ON THE LOWER SIDE BUT HELPED BY A  
LIGHTER TREND IN RECENT GFS RUNS WHICH HAD BEEN A HEAVY EXTREME.  
 
THE CHANGE AND PROGRESSION OF THE OVERALL PATTERN WILL BE EVIDENT  
IN TEMPERATURES OVER THE COURSE OF NEXT WEEK, AS WARMER THAN  
AVERAGE TEMPERATURES PUSH EASTWARD AHEAD OF THE TROUGH/FRONTAL  
SYSTEM AND COOLER TEMPERATURES SPREAD BEHIND THE COLD FRONT. HIGHS  
OF 10-20F ABOVE AVERAGE AND LOWS 15-30F ABOVE NORMAL WILL BE  
SHUNTED FROM THE SOUTHERN HALF OF THE PLAINS INTO THE MISSISSIPPI  
AND OHIO/TENNESSEE VALLEYS WEDNESDAY INTO THE EASTERN SEABOARD ON  
THURSDAY. DAILY RECORDS COULD BE SET FOR SOME LOCATIONS,  
ESPECIALLY FOR WARM LOWS IN THE EAST ON THURSDAY, WHILE A FEW  
RECORD HIGH MAXIMA COULD BE CHALLENGED AS WELL. ON THE BACKSIDE OF  
THE FRONT, TEMPERATURES SHOULD FLIP TO NEAR OR BELOW AVERAGE, WITH  
SOME 10-20F BELOW AVERAGE READINGS POSSIBLE OVER PARTS OF THE  
CENTRAL/EAST-CENTRAL U.S. MID-LATE WEEK AND THEN MODERATING CLOSER  
TO THE EAST COAST. COLDEST ANOMALIES SHOULD BE OVER/NEAR MINNESOTA  
AROUND THURSDAY WITH SOME PLACES 20-30F BELOW NORMAL. AN  
INCREASING PORTION OF THE WEST AND EVENTUALLY THE NORTHERN/CENTRAL  
PLAINS SHOULD WARM UP TO ABOVE AVERAGE ONCE AGAIN BY THE END OF  
THE WEEK INTO THE WEEKEND. PARTS OF THE GREAT BASIN AND VICINITY  
COULD SEE HIGHS AT LEAST 10F ABOVE NORMAL, WHILE CENTRAL PARTS OF  
THE PLAINS COULD EVEN REACH 20F ABOVE AVERAGE WITH TEMPERATURES IN  
THE 60S BY SUNDAY.  
 
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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