672  
FXUS02 KWBC 262105  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
404 PM 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 IMPACTS 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
 
 
MODEL GUIDANCE FOR THE MOST RECENT COUPLE OF CYCLES CONTINUES TO  
SHOW A RAPIDLY DEEPENING (BOMB) CYCLONE IN THE WESTERN ATLANTIC  
OVER THE WEEKEND, BUT CONTINUES TO WAFFLE SOMEWHAT WITH ITS EXACT  
TRACK, AND THE RELATIVELY FINE-SCALE WOBBLES CAN CAUSE NOTABLY  
DIFFERENT WEATHER IMPACTS. 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.  
ECMWF RUNS HAVE BEEN REASONABLY PERSISTENT ON THE EARLIER/DEEPER  
SIDE WITH GFS RUNS AT LITTLE LATER/WEAKER. OVERALL THE FORECAST  
POSITION FOR THE LOW ON SATURDAY AND SUNDAY WAS VERY SIMILAR TO  
THE PREVIOUS WPC FORECAST ISSUANCE, PER THE 00Z/06Z MODEL  
CONSENSUS AND TAKING SOMEWHAT OF AN AVERAGE POSITION BETWEEN THE  
SLIGHTLY SLOWER EC OTHER FASTER MODELS. HOWEVER, INCOMING 12Z  
GUIDANCE HAS SHOWN A SLIGHTLY EASTWARD/MORE OFFSHORE TREND  
PARTICULARLY ON SATURDAY.  
 
MODELS CONTINUE TO IMPROVE THEIR AGREEMENT WITH THE SMALL UPPER  
TROUGH/LOW MOVING FROM THE PACIFIC INTO THE SOUTHWEST OVER THE  
WEEKEND AND THE SOUTHERN PLAINS EARLY MONDAY BEFORE WEAKENING AS  
IT HEADS INTO A DEVELOPING MEAN RIDGE IN THE EAST. HOWEVER, MORE  
MODEL DIFFERENCES ARISE WITH THE DEEPER UPSTREAM TROUGHING  
EXPECTED TO DIG DURING THE FIRST HALF OF NEXT WEEK IN THE WEST.  
THE GENERAL TREND IN THE 00Z/06Z MODEL GUIDANCE WAS A SLIGHTLY  
FASTER TROUGH AXIS MOVING EASTWARD ESPECIALLY BY  
TUESDAY-WEDNESDAY, WHICH PUSHED THE COLD FRONT AHEAD OF IT FASTER  
THAN THE PREVIOUS FORECAST. THERE IS STILL CONSIDERABLE  
UNCERTAINTY WITH THE MULTIPLE PIECES OF ENERGY SERVING TO  
CREATE/DIG THIS TROUGH, WHICH MAINLY STEM FROM HIGH  
LATITUDE/PACIFIC REGIONS WITH LOW PREDICTABILITY. OF THE 00Z MODEL  
CYCLE, THE CMC SHOWED SOME STREAM SEPARATION PRODUCING A SOUTHERN  
STREAM LOW DIVING OFF THE COAST OF CALIFORNIA MONDAY-TUESDAY  
UNLIKE OTHER GUIDANCE. THIS APPEARED TO BE SOMEWHAT OF AN OUTLIER  
BASED ON CONSENSUS AND MOST INDIVIDUAL ENSEMBLE MEMBERS, BUT THE  
NEW 12Z GFS ENDED UP LOOKING QUITE SIMILAR TO THAT 00Z CMC, WHILE  
THE 12Z CMC ENDED UP WITHOUT THIS PATTERN, CLOSING OFF A SOUTHERN  
STREAM LOW WELL WEST IN THE PACIFIC AS DID THE INCOMING 12Z ECMWF.  
THIS IS JUST AN INDICATION THAT THOUGH MODEL GUIDANCE MAY INDICATE  
AGREEMENT AT TIMES, THERE IS STILL LOW CONFIDENCE IN THE DETAILS,  
AND THE FORECAST STILL MAY GO THROUGH CHANGES WITH THE TROUGH AXIS  
AND FRONTAL TIMING.  
 
A MULTI-MODEL DETERMINISTIC BLEND WAS USED EARLY IN THE MEDIUM  
RANGE FORECAST PERIOD, WITH THE 00Z/06Z GFS RUNS AND THE 00Z  
ECMWF, CMC, AND UKMET. GRADUALLY INCREASED THE INCORPORATION OF  
THE GEFS AND EC ENSEMBLE MEANS TO ABOUT HALF BY THE END OF THE  
PERIOD GIVEN INCREASING MODEL DIFFERENCES AND UNCERTAINTY.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
TO START THE PERIOD SATURDAY, HEAVY SNOW IS LIKELY ACROSS THE  
NORTHEAST WITH POSSIBLY SOME SNOW LINGERING IN THE COASTAL  
MID-ATLANTIC REGION. LATEST FORECASTS SHOW THE HIGHEST CONFIDENCE  
IN HEAVY SNOW AMOUNTS LIKELY NEAR COASTAL NEW ENGLAND. 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. SEE THE WPC WEBSITE FOR UPDATED KEY  
MESSAGES ON THE SYSTEM AND CHECK YOUR LOCAL FORECAST AT  
WEATHER.GOV.  
 
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  
IN THE SOUTH-CENTRAL U.S. 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 AVERAGE READINGS  
OVER TEXAS AND VICINITY, MUCH OF THE PLAINS WILL SEE ABOVE AVERAGE  
TEMPERATURES FROM THE WEEKEND INTO NEXT WEEK WITH READINGS UP TO  
10-20F OR SO ABOVE NORMAL, LOCALLY HIGHER. 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 AVERAGE  
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.  
 
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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE MIDDLE/LOWER MISSISSIPPI  
VALLEY, THE TENNESSEE VALLEY, THE  
GREAT LAKES, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO  
VALLEY, WED, FEB 2.  
- HEAVY SNOW ACROSS PORTIONS OF THE MID-ATLANTIC AND THE  
NORTHEAST, SAT-SUN, JAN 29-JAN 30.  
- HIGH WINDS ACROSS PORTIONS OF THE SOUTHEAST, THE MID-ATLANTIC,  
AND THE NORTHEAST, SAT-SUN, JAN  
29-JAN 30.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE  
MID-ATLANTIC, THE MISSISSIPPI VALLEY, THE  
CENTRAL/SOUTHERN APPALACHIANS, THE TENNESSEE VALLEY, THE  
NORTHEAST, THE SOUTHEAST, THE GREAT LAKES,  
AND THE OHIO VALLEY, SAT-SUN, JAN 29-JAN 30.  
- HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF THE  
MID-ATLANTIC AND THE NORTHEAST, SAT,  
JAN 29.  
 
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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