641  
FXUS02 KWBC 140705  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
205 AM EST MON FEB 14 2022  
 
VALID 12Z THU FEB 17 2022 - 12Z MON FEB 21 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
 
 
NORTHERN AND SOUTHERN STREAM UPPER-LEVEL TROUGHS WILL BE IN THE  
PROCESS OF PHASING IN THE CENTRAL U.S. AS THE MEDIUM RANGE PERIOD  
BEGINS THURSDAY, WHICH WILL SHIFT EASTWARD THROUGH THE END OF THE  
WEEK. AT THE SURFACE, LOW PRESSURE IS FORECAST TO STRENGTHEN AS IT  
TRACKS QUICKLY NORTHEAST AND THE ASSOCIATED STRONG COLD FRONT WILL  
PUSH AHEAD OF THE TROUGH AXIS, DRAWING MOISTURE NORTHWARD FROM THE  
GULF OF MEXICO AND PRODUCING NOTABLE PRECIPITATION ACROSS THE  
EASTERN THIRD OF THE U.S. ON THURSDAY. EXPECT RAIN AND  
THUNDERSTORMS IN SOUTHERN AREAS, INCLUDING THE POSSIBILITY OF  
FLASH FLOODING AND SEVERE WEATHER, WHILE SNOW AND WINTRY WEATHER  
ARE LIKELY ON THE NORTHERN AND WESTERN SIDE OF THE PRECIPITATION  
SHIELD ACROSS THE MIDDLE MISSISSIPPI VALLEY AND MIDWEST, GREAT  
LAKES, AND POSSIBLY THE 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 WEAKENING RIDGE MAKING ITS WAY INTO  
THE WEST COAST WILL BE OVERCOME BY ADDITIONAL TROUGHING ENTERING  
THE WEST EARLY NEXT WEEK.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE OVERALL PATTERN SHOWS FAIRLY GOOD AGREEMENT TO START THE  
PERIOD THURSDAY-FRIDAY. MODEL GUIDANCE SEEMS TO HAVE COME TO A  
"HAPPY MEDIUM" MIDPOINT SOLUTION WITH THE TIMING AND TRACK OF THE  
TROUGH AND SURFACE LOW/FRONT AND THUS THE PRECIPITATION  
SHIELD--FASTER AND INITIALLY WEAKER THAN WHAT WAS FORECAST A FEW  
DAYS AGO BUT TRENDING SLIGHTLY STRONGER AND SLOWER OVER THE PAST  
DAY OR SO. GOOD CONTINUITY REMAINS THAT THE SURFACE LOW WILL  
INTENSIFY QUICKLY AS IT TRACKS NORTHEAST THURSDAY INTO FRIDAY.  
AFTER A FEW DAYS OF THE CMC BEING OUT OF TOLERANCE WITH OTHER  
SOLUTIONS, THE 12Z RUN SEEMED MORE IN LINE ESPECIALLY WITH ITS  
UPPER PATTERN. THE EARLY PART OF THE MEDIUM RANGE WPC FORECAST WAS  
BASED ON A COMPOSITE OF THE 12Z/18Z GFS AND 12Z ECMWF, UKMET, AND  
CMC RUNS, WITH ONLY MODEST NUDGES FROM CONTINUITY.  
 
UPSTREAM OF THE INITIAL TROUGH, CONSIDERABLE VORTICITY/ENERGY  
DROPS INTO CENTRAL CANADA AND SHIFTS TOWARD THE GREAT LAKES FOR  
THE END OF THE WEEK, AND RECENT MODELS SHOW BETTER THAN AVERAGE  
AGREEMENT WITH THE ASSOCIATED SURFACE LOW/CLIPPER TRACK AND  
STRENGTH THROUGH EARLY SATURDAY, UNTIL SOME DIFFERENCES ARISE WITH  
THE EXACT AMPLITUDE OF THE RESULTING UPPER TROUGH AND THUS  
VARIABILITY WITH THE TRAILING FRONT INTO THE EAST. A MORE  
UNCERTAIN FEATURE IS A COMPACT SHORTWAVE ROUNDING THE RIDGE IN THE  
EASTERN PACIFIC THAT COULD ENTER THE PACIFIC NORTHWEST AROUND  
FRIDAY NIGHT AND MOVE EASTWARD, BUT WITH DIFFERENCES IN THE TIMING  
AND PLACEMENT, WHICH MAY NOT BE RESOLVED FOR A WHILE GIVEN THE  
SMALL SCALE OF THIS FEATURE. THE LARGER SCALE TROUGH MAKING ITS  
WAY TOWARD THE WEST EARLY NEXT WEEK DEMONSTRATES NOTABLE  
DIFFERENCES AS ENERGY SPILLS IN FROM THE LOW PREDICTABILITY HIGH  
LATITUDES. GFS RUNS HAVE BEEN ON THE STRONGER AND SLOWER SIDE WITH  
THE TROUGH, ESPECIALLY THE 12Z RUN BUT THE 18Z AND 00Z RUNS ARE  
SOMEWHAT SLOW COMPARED TO CONSENSUS AS WELL. THE ECMWF RUNS HAVE  
BEEN FAIRLY STABLE IN THE MIDDLE SO FAR, WHILE THE CMC HAS BEEN  
SLIGHTLY FASTER. THUS FOR THE LATTER PART OF THE FORECAST PERIOD,  
THE WPC FORECAST FAVORED THE ECMWF IN TERMS OF THE DETERMINISTIC  
MODELS, AND GRADUALLY PHASED IN SOME OF THE MORE AGREEABLE GEFS  
AND EC ENSEMBLE MEANS TO ABOUT HALF BY THE END OF THE PERIOD TO  
TEMPER INDIVIDUAL MODEL DIFFERENCES.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
ON THURSDAY, SHOWERS AND THUNDERSTORMS WILL BE WIDESPREAD FROM THE  
LOWER MISSISSIPPI VALLEY NORTH AND EASTWARD ACROSS THE  
TENNESSEE/OHIO VALLEYS, APPALACHIANS, AND EASTERN SEABOARD AS A  
SURFACE LOW/FRONTAL SYSTEM ADVECTS SUBSTANTIAL MOISTURE FROM THE  
GULF OF MEXICO NORTHWARD. STRONG STORMS ARE POSSIBLE, WITH THE  
STORM PREDICTION CENTER OUTLOOK SHOWING SOME SEVERE THREAT FOR THE  
MID-SOUTH. THERE COULD ALSO BE FLASH FLOODING CONCERNS WHERE HEAVY  
RAINFALL OCCURS 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 ON THURSDAY INTO  
THURSDAY NIGHT CURRENTLY EXTENDS FROM THE MIDDLE MISSISSIPPI  
VALLEY INTO THE MIDWEST/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 THE  
SNOW AXIS WILL BE VERY SENSITIVE TO PRECISE STRENGTH AND TRACK OF  
THE SYSTEM GIVEN THAT WINTRY WEATHER COULD BE WITHIN A FAIRLY  
NARROW BAND. GUSTY WINDS ARE POSSIBLE WITH THE SYSTEM AS WELL, AND  
AT THIS POINT APPEAR MOST LIKELY NEAR THE NORTHEAST COAST ON  
THURSDAY NIGHT/FRIDAY MORNING IN STRONG SOUTHERLY FLOW AHEAD OF  
THE QUICKLY STRENGTHENING SURFACE LOW.  
 
DRY CONDITIONS SHOULD PREVAIL OVER MUCH OF THE LOWER 48 BEHIND  
THIS SYSTEM, WITH A FEW EXCEPTIONS. THE CLIPPER SYSTEM ALONG THE  
CANADIAN BORDER MAY BRING SOME SNOW INTO THE GREAT LAKES REGION BY  
FRIDAY AND SATURDAY. MEANWHILE, SOME RAIN SHOWERS COULD PERSIST IN  
FLORIDA WITH LINGERING MOISTURE THERE, BUT RAINFALL AMOUNTS REMAIN  
UNCERTAIN. LIGHT PRECIPITATION COULD ALSO MAKE ITS WAY INTO THE  
NORTHWEST BY FRIDAY, WITH AMOUNTS INCREASING TO LOCALLY MODERATE  
AND SPREADING SOUTH AND EASTWARD ACROSS THE WEST OVER THE WEEKEND  
AS THE UPPER TROUGH COMES IN.  
 
AHEAD OF THE COLD FRONT PUSHING ACROSS THE EASTERN U.S. LATE IN  
THE WORKWEEK, WARMER THAN AVERAGE TEMPERATURES BY 10-25F WILL BE  
WIDESPREAD ACROSS THE EASTERN THIRD OF THE U.S. ON THURSDAY, AND  
DAILY RECORDS COULD BE SET FOR SOME LOCATIONS, ESPECIALLY FOR WARM  
LOWS, 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. ON THURSDAY AND THEN  
MODERATING CLOSER TO THE EAST COAST FRIDAY AND SATURDAY. 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.  
 
TATE/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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