607  
FXUS02 KWBC 151812  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
111 PM EST SAT JAN 15 2022  
 
VALID 12Z TUE JAN 18 2022 - 12Z SAT JAN 22 2022  
   
..PATTERN OVERVIEW
 
 
A WINTER STORM WILL BE EXITING THE NORTHEAST AS THE PERIOD BEGINS  
WHILE A MEAN UPPER RIDGE WORKS TO AMPLIFY ALONG/OFF THE WEST COAST  
BY MID TO LATER NEXT WEEK. THIS SHOULD FORCE AN INCREASINGLY  
DOMINANT SERIES OF NORTHERN STREAM IMPULSES INTO THE NORTH-CENTRAL  
U.S. THROUGH THE PERIOD. THE FIRST OF WHICH SHOULD SLIDE OVER THE  
GREAT LAKES INTO THE NORTHEAST WEDNESDAY AND THURSDAY, WITH THE  
NEXT QUICKLY ON ITS HEELS DIGGING FARTHER INTO THE MID-SOUTH ON  
FRIDAY AND OFF THE MID-ATLANTIC COAST ON SATURDAY. THESE SYSTEMS  
WILL HELP CARVE OUT AND REINFORCE LARGE MEAN TROUGHING WHICH  
SHOULD MAINTAIN OVER THE MIDWEST AND EAST LATE NEXT WEEK AND INTO  
THE WEEKEND.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE LATEST 00Z/06Z GUIDANCE FOR TODAY CONTINUES TO SHOW GOOD  
AGREEMENT ON THE OVERALL SYNOPTIC SET-UP THROUGH MUCH OF THE  
EXTENDED RANGE. THERE REMAINS SOME SMALLER SCALE DETAIL  
UNCERTAINTIES NEEDING RESOLVING, INCLUDING TIMING AND AMPLITUDE OF  
THE COUPLE OF SHORTWAVES REINFORCING MEAN TROUGHING CENTERED  
ACROSS THE MIDWEST. THE LATE PERIOD SHORTWAVE INTO THE MID-SOUTH  
AND OFF THE EAST COAST CONTINUES TO SHOW VARIABILITY IN THE MODELS  
AND HAS POTENTIAL FOR A SURFACE LOW MOVING THROUGH THE SOUTHEAST  
AND OFF THE EAST COAST. MOST OF THE GUIDANCE RIGHT NOW SHOWS A  
FAIRLY WEAK/PROGRESSIVE SURFACE LOW WHICH SHOULD QUICKLY SHIFT  
WELL OFF INTO THE ATLANTIC. THIS SYSTEM IS WORTH MONITORING THOUGH  
AS WE GET CLOSER IN TIME BECAUSE IT COULD HAVE WINTRY WEATHER  
IMPACTS FOR PARTS OF THE EAST COAST, DEPENDING ON THE EXACT TRACK  
AND OVERALL STRENGTH. OUT WEST, MODELS AGREE THAT UPPER RIDGING  
SHOULD AMPLIFY THROUGH THE PERIOD. THE GFS HAS BEEN FAIRLY  
CONSISTENT SHOWING A CLOSED LOW DEVELOPING OFF THE SOUTHERN  
CALIFORNIA COAST AROUND THURSDAY-FRIDAY NEXT WEEK, BUT IT DOESN'T  
HAVE MUCH SUPPORT FROM OTHER PIECES OF GUIDANCE, MOST OF WHICH ARE  
MUCH MORE PROGRESSIVE WITH THE SHORTWAVE INTO THE SOUTHERN PLAINS.  
THE ECMWF ALSO SHOWS A COMPACT UPPER LOW BREAKING OFF TROUGHING  
ACROSS THE NORTHEAST PACIFIC WHICH MAY TRY TO WEAKEN THE RIDGE A  
BIT. GIVEN THESE SMALL SCALE DETAILS, WHICH DON'T HAVE A WHOLE LOT  
OF RUN TO RUN CONTINUITY, IT SEEMS PRUDENT TO LEAN MORE ON THE  
ENSEMBLE MEANS LATER IN THE PERIOD.  
 
THE WPC FORECAST FOR TODAY USED A BLEND OF MAJORITY DETERMINISTIC  
SOLUTIONS DAYS 3-5. AFTER THAT, ELIMINATED THE GFS DUE TO ITS  
OUTLYING SOUTHERN CALIFORNIA LOW, AND REPLACED IT WITH INCREASING  
PARTS OF THE ENSEMBLE MEANS. THIS APPROACH AFFORDED A FORECAST  
VERY CLOSE TO PREVIOUS WPC CONTINUITY AS WELL.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
A SIGNIFICANT WINTER STORM IS SLATED TO EXIT NEW ENGLAND INTO TO  
THE CANADIAN MARITIMES BY TUESDAY, ALTHOUGH GUSTY WINDS MAY  
CONTINUE THROUGH THE DAY. ANOTHER ORGANIZED LOW PRESSURE SYSTEM  
DIGS INTO THE NORTH-CENTRAL U.S. BEHIND THIS WITH LOW DEVELOPMENT  
AND SUBSEQUENT TRACK MOVING EASTWARD ALONG THE U.S./CANADIAN  
BORDER INTO WED/THU. THIS SHOULD BRING SOME SNOW TO THE UPPER  
MIDWEST, GREAT LAKES THEN NORTHERN NEW ENGLAND, WITH LOCALLY  
HIGHER TOTALS EXPECTED NEAR TYPICAL LAKE ENHANCEMENT AREAS AS COLD  
HIGH PRESSURE SWEEPS DOWN ACROSS THE CENTRAL AND EASTERN U.S. IN  
THE WAKE OF THE LOW. GUIDANCE VARIES WITH POTENTIAL FOCUS, BUT  
SUSPECT THE WAVY TRAILING COLD FRONT ON THE LEADING EDGE OF THIS  
ARCTIC BLAST WILL GAIN AT LEAST MODEST MOISTURE FROM THE GULF OF  
MEXICO TO FUEL AN EMERGING AREA OF PRECIPITATION OVER THE  
SOUTHEAST THAT OFFERS SOME LATER NEXT WEEK POTENTIAL FOR  
OVERRUNNING SNOW/ICE ON THE NORTHERN PERIPHERY OF ACTIVITY. THERE  
ARE SOME ENSEMBLE MEMBERS WHICH ARE MORE ROBUST WITH  
FRONTAL/COASTAL WAVE AMPLITUDE AND PRECIPITATION EXTENT ACROSS THE  
REGION AND OVER THE EAST COAST AT THESE LONGER TIME PERIODS. THE  
MAIN UPPER TROUGH POSITION IS FAR ENOUGH WEST TO NOT DISCOUNT THIS  
POSSIBILITY. MEANWHILE, THE WEST COULD SEE SOME LIGHT  
PRECIPITATION THROUGH THE PERIOD, PARTICULARLY OVER THE PACIFIC  
NORTHWEST AND INTO THE NORTHERN ROCKIES AS WEAKENING SYSTEMS CROSS  
THE REGION, WITH MAINLY DRY CONDITIONS ELSEWHERE.  
 
A WARM DAY ON TUESDAY ACROSS THE CENTRAL PART OF THE NATION WILL  
QUICKLY CHANGE AS A VERY COLD CANADIAN HIGH PRESSURE DIGS  
SOUTHWARD INTO THE REGION AND EVENTUALLY THE EAST. MUCH BELOW  
NORMAL TEMPERATURES (-15 TO -20F) WILL SLIDE EAST FROM THE  
NORTHERN PLAINS/UPPER MIDWEST ON WEDNESDAY-THURSDAY REACH THE  
SOUTH AND EAST BY NEXT FRIDAY. WEST OF THE ROCKIES SHOULD  
GENERALLY STAY NEAR OR SLIGHTLY ABOVE NORMAL THROUGHOUT THE WEEK  
AS UPPER LEVEL RIDGING BECOMES ANCHORED OVER THE REGION.  
 
SANTORELLI  
 
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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