791  
FXUS02 KWBC 260659  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
159 AM EST WED JAN 26 2022  
 
VALID 12Z SAT JAN 29 2022 - 12Z WED FEB 02 2022  
 
...COASTAL WINTER STORM THREAT FROM THE MID-ATLANTIC TO ESPECIALLY  
NEW ENGLAND FRIDAY INTO THE WEEKEND...  
 
   
..OVERVIEW
 
 
EARLY IN THE MEDIUM RANGE PERIOD FROM SATURDAY INTO EARLY SUNDAY,  
A DEEP UPPER TROUGH REACHING THE EAST COAST WILL LIKELY CLOSE OFF  
AN EMBEDDED UPPER LOW THAT TRACKS NEAR THE NEW ENGLAND COAST. THE  
EVOLUTION ALOFT WILL SUPPORT FURTHER DEEPENING OF STRONG LOW  
PRESSURE JUST OFF THE EAST COAST AND DIRECT THE SYSTEM NORTHWARD,  
FROM EAST OF THE MID-ATLANTIC COAST INTO THE CANADIAN MARITIMES.  
THIS STRONG COASTAL STORM MAY CAUSE HEAVY SNOW IN THE COASTAL  
MID-ATLANTIC REGION WITH HIGHER CONFIDENCE FOR HEAVY SNOW OVER THE  
NORTHEAST, WHERE HIGH WINDS AND COASTAL FLOODING ARE ALSO LIKELY  
THROUGH THE WEEKEND. AT THE SAME TIME A WEAK EASTERN PACIFIC  
TROUGH/UPPER LOW WILL CUT THROUGH THE SOUTHERN PART OF INITIAL  
RIDGING OVER THE WEST. FROM LATE WEEKEND INTO NEXT WEEK A MORE  
POTENT UPPER TROUGH WILL PUSH INTO THE WEST AND STEADILY AMPLIFY,  
ULTIMATELY FLIPPING THE UPPER PATTERN AS A RIDGE AXIS REACHES THE  
EAST COAST BY WEDNESDAY. THIS CONFIGURATION SHOULD LEAD TO A  
PRONOUNCED INCREASE OF PRECIPITATION OVER THE CENTRAL U.S. BY THE  
END OF THE FORECAST PERIOD.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
LATEST GUIDANCE CONTINUES TO FAVOR AN INTERMEDIATE/CONSENSUS  
APPROACH FOR DEPICTING THE WESTERN ATLANTIC STORM DURING THE  
WEEKEND. A SIGNIFICANT KEY TO THE FORECAST OF THE SURFACE LOW BY  
LATE SATURDAY APPEARS TO BE EXACTLY WHEN, WHERE, AND HOW DEEPLY  
THE UPPER LOW WITHIN THE OVERALL TROUGH CLOSES OFF. IN GENERAL GFS  
RUNS HAVE TENDED TO BE A LITTLE LATER/WEAKER WITH THE UPPER LOW  
WHILE THE 12Z ECMWF IS SOMEWHAT ON THE EARLIER/DEEPER SIDE. THE  
12Z ECMWF SCENARIO BRINGS THE SURFACE TRACK BACK TO THE WEST FOR A  
BRIEF TIME, WHICH A NUMBER OF ECMWF ENSEMBLES HAVE ALSO BEEN  
DOING. THE 00Z CMC HAS A LESS PRONOUNCED AND FARTHER NORTH  
DEPICTION OF THIS IDEA. THE NEW 00Z ECMWF HAS ADJUSTED EAST WITH  
THE SURFACE LOW TOWARD THE LONGER-TERM CONSENSUS DUE TO A SLIGHTLY  
WEAKER UPPER LOW. THIS IS A VERY FINE-SCALE DETAIL AND THE  
SUPPORTING ENERGY IS STILL OVER NORTHWESTERN NORTH AMERICA SO IT  
MAY TAKE ADDITIONAL TIME TO RESOLVE SPECIFICS WITH REASONABLE  
SATISFACTION.  
 
FOR THE UPPER TROUGH MOVING INTO THE WEST, THE FORECAST OF LEADING  
ENERGY HAS BECOME MORE UNCERTAIN IN THE NEW 00Z CYCLE AS MODELS  
SHOW VARYING WAYS IN WHICH SOME OF THE ENERGY IN THE SHORTWAVE MAY  
GET PULLED OFF TO THE SOUTHWEST--LEADING TO MEANINGFUL DIFFERENCES  
IN AMPLITUDE AS THE REMAINING ENERGY REACHES THE WEST COAST. ON  
THE OTHER HAND, GUIDANCE FROM THE 12Z CYCLE ONWARD SEEMS TO HAVE  
COME INTO BETTER AGREEMENT FOR THE PATTERN FROM THE NORTH PACIFIC  
THROUGH ALASKA AND SIBERIA. THIS HAS IN TURN HELPED TO NARROW THE  
SPREAD SOMEWHAT FOR THE LARGER SCALE UPPER TROUGH AMPLIFYING INTO  
THE WEST DURING THE FIRST HALF OF THE WEEK.  
 
MODELS ARE SLOWLY IMPROVING THEIR AGREEMENT WITH RESPECT TO THE  
WEAK UPPER TROUGH/LOW MOVING INTO THE SOUTHWEST DURING THE WEEKEND  
AND CONTINUING ALONG THE SOUTHERN TIER BEFORE WEAKENING AS IT  
HEADS INTO A DEVELOPING MEAN RIDGE IN THE EAST. GENERAL TRENDS BY  
THE TIME THE FEATURE REACHES THE PLAINS HAVE BEEN MORE IN THE  
DIRECTION OF THE SOUTHERN ECMWF VERSUS SOME EARLIER NORTHERN GFS  
RUNS.  
 
THE UPDATED FORECAST STARTED WITH A BLEND OF 12Z MODELS, WITH  
MINOR MANUAL ENHANCEMENT OF THE WESTERN ATLANTIC STORM. THE 12Z  
GFS COMPARED SLIGHTLY BETTER IN CONCEPT TO OTHER GUIDANCE VERSUS  
THE 18Z RUN. MEANWHILE THE MODEL BLEND ACCOUNTED FOR THE MOST  
COMMON IDEAS FOR THE ARRIVING WESTERN TROUGH AS OF THE 12Z/18Z  
CYCLES. BY LATER IN THE PERIOD AN AVERAGE OF RECENT OPERATIONAL  
MODEL RUNS HAS FAIRLY GOOD SUPPORT FROM THE GEFS/ECMWF MEANS FOR  
THE AMPLIFYING WESTERN TROUGH, SO EVEN BY DAYS 6-7  
TUESDAY-WEDNESDAY THE FORECAST INCLUDED ONLY 30 PERCENT TOTAL  
ENSEMBLE MEAN WEIGHT.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
KEY MESSAGES FOR JANUARY 28-30 (FRIDAY-WEEKEND) WINTER STORM:  
CONFIDENCE IS INCREASING THAT A SIGNIFICANT WINTER STORM WILL  
CREATE CONSIDERABLE IMPACTS FRIDAY THROUGH THE WEEKEND FROM THE  
MID-ATLANTIC THROUGH THE NORTHEAST. HEAVY SNOW IS MOST LIKELY IN  
PARTS OF NEW ENGLAND. HEAVY SNOW IS STILL POSSIBLE FARTHER SOUTH  
ALONG THE EAST COAST, INCLUDING THE MAJOR I-95 METROPOLITAN AREAS  
FROM NEW YORK CITY TO WASHINGTON D.C., BUT THAT IS MORE UNCERTAIN  
AT THIS TIME. SIGNIFICANT COASTAL IMPACTS ARE POSSIBLE IN THE  
NORTHEAST, INCLUDING COASTAL FLOODING AND BEACH EROSION.  
ADDITIONALLY, STRONG WINDS MAY CAUSE BLOWING SNOW AND SOME DAMAGE.  
HAZARDOUS TRAVEL CONDITIONS ARE LIKELY IN PARTS OF THE REGION.  
PLEASE CONTINUE TO MONITOR FOR UPDATES, AND CHECK YOUR LOCAL  
FORECAST AT WEATHER.GOV.  
 
OTHER WEATHER HIGHLIGHTS:  
IT STILL APPEARS THAT THE UPPER TROUGH/LOW THAT MAY TRACK INTO  
CALIFORNIA AND THE SOUTHWEST THIS WEEKEND MAY BE WEAK ENOUGH NOT  
TO PRODUCE MUCH IF ANY PRECIPITATION OVER THAT REGION. ITS  
STRENGTH AND TRACK THEREAFTER WILL DETERMINE HOW MUCH  
PRECIPITATION MAY DEVELOP FROM THE GULF COAST NORTHWARD BY THE  
FIRST PART OF NEXT WEEK. OVER THE PAST DAY GUIDANCE HAS STARTED TO  
SHOW SOME CONVERGENCE TOWARD THE IDEA OF AT LEAST SOME MEANINGFUL  
RAINFALL ALONG AND NORTH OF THE WESTERN HALF OF THE GULF COAST BY  
MONDAY. MOISTURE AHEAD OF A NORTHEASTERN PACIFIC UPPER TROUGH  
SHOULD BEGIN TO MOVE INTO THE NORTHWEST ON SUNDAY AND THEN  
CONTINUE TO SPREAD ACROSS MORE OF THE WEST WITH TIME AS THE UPPER  
TROUGH MOVES INLAND AND AMPLIFIES. HIGHEST TOTALS OF RAIN/MOUNTAIN  
SNOW SHOULD BE OVER THE PACIFIC NORTHWEST, BUT AMOUNTS DO NOT  
APPEAR TOO SIGNIFICANT AT THIS TIME. TOWARD MIDWEEK THE WESTERN  
TROUGH AND LEADING SURFACE FRONT WILL INTERACT WITH A HEALTHY FLOW  
OF GULF MOISTURE TO PRODUCE A RAPIDLY EXPANDING AREA OF  
PRECIPITATION, SOME OF IT POTENTIALLY BECOMING MODERATE TO HEAVY.  
LIGHTER WINTRY PRECIPITATION WILL BE POSSIBLE OVER NORTHERN  
LATITUDES. A SERIES OF WAVES/FRONTS MAY BRING EPISODES OF LIGHT  
AND SCATTERED SNOW INTO PARTS OF THE GREAT LAKES BEFORE THE LARGER  
SCALE PATTERN CHANGES.  
 
THE EASTERN U.S. WILL BE QUITE CHILLY THROUGH THE WEEKEND WITH  
BROAD COVERAGE OF TEMPERATURES 10-20F BELOW NORMAL, INCLUDING  
SUBFREEZING LOWS EXTENDING INTO PORTIONS OF FLORIDA. AREAS FROM  
THE MISSISSIPPI VALLEY TO APPALACHIANS SHOULD SEE A MODERATING  
TREND FROM WEST TO EAST. ASIDE FROM SOME BELOW NORMAL READINGS  
OVER TEXAS AND VICINITY, MUCH OF THE PLAINS WILL SEE ABOVE NORMAL  
TEMPERATURES FROM THE WEEKEND INTO NEXT WEEK WITH READINGS UP TO  
10-20F OR SO ABOVE NORMAL. THIS WARMTH WILL PROGRESS INTO THE  
EASTERN HALF OF THE COUNTRY EARLY-MID WEEK WITH THE INCREASE OF  
GULF MOISTURE HELPING TO RAISE MIN TEMPERATURE ANOMALIES IN  
PARTICULAR BY WEDNESDAY. MODERATELY ABOVE NORMAL TEMPERATURES OVER  
THE WEST DURING THE WEEKEND WILL TREND LOWER NEXT WEEK WITH THE  
ARRIVAL OF AN AMPLIFYING UPPER TROUGH AND 5-15F BELOW NORMAL HIGHS  
MAY EXTEND FROM THE INTERIOR WEST INTO THE HIGH PLAINS/NORTHERN  
TIER BY TUESDAY-WEDNESDAY.  
 
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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