392  
FXUS02 KWBC 250653  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
152 AM EST TUE JAN 25 2022  
 
VALID 12Z FRI JAN 28 2022 - 12Z TUE FEB 01 2022  
 
...WINTER COASTAL STORM THREAT FROM THE MID-ATLANTIC TO ESPECIALLY  
NEW ENGLAND FRIDAY INTO THE WEEKEND...  
 
   
..OVERVIEW
 
 
FROM LATE THIS WEEK TO THE START OF NEXT WEEK THE MODELS AND  
ENSEMBLES CONTINUE TO SHOW AN UPPER LEVEL PATTERN CONSISTING OF A  
MEAN TROUGH OVER THE EAST, VARYING DEGREES OF RIDGING OVER THE  
WEST, AND A DEVELOPING NORTHEASTERN PACIFIC TROUGH THAT SHOULD  
APPROACH/REACH THE WEST COAST. GUIDANCE EXPECTS THE INLAND  
PROGRESSION OF THE PACIFIC TROUGH BY MONDAY-TUESDAY TO FLIP THE  
PATTERN SOMEWHAT, WITH DECREASING HEIGHTS OVER THE WEST AND RISING  
HEIGHTS OVER THE EAST. PERHAPS DUE IN PART FROM IMPROVING  
AGREEMENT FOR A LEAD PACIFIC SHORTWAVE/POSSIBLE WEAK EMBEDDED LOW  
NEARING CALIFORNIA BY SATURDAY, THERE IS LIKEWISE NARROWING SPREAD  
OF SOLUTIONS FOR ENERGY DIGGING INTO AN AMPLIFIED U.S. TROUGH THAT  
LOOKS INCREASINGLY LIKELY TO SUPPORT A SIGNIFICANT AND RAPIDLY  
DEEPENING WESTERN ATLANTIC COASTAL STORM FRIDAY INTO THE WEEKEND  
WITH EFFECTS FROM THE MID-ATLANTIC TO NEW ENGLAND IN PARTICULAR.  
SOME DIFFERENCES PERSIST FOR DETAILS OF THE UPPER TROUGH MOVING  
INTO THE WEST.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
EMERGING TRENDS FROM YESTERDAY ALONG BOTH COASTS OF THE LOWER 48  
DURING THE LATE WEEK/WEEKEND TIME FRAME HELD UP FAIRLY WELL IN THE  
12Z/18Z CYCLE OF GUIDANCE. SLOWER AND MORE SEPARATED EVOLUTION OF  
THE SHORTWAVE APPROACHING CALIFORNIA, LIKELY YIELDING A WEAK UPPER  
LOW, ALLOWS FOR A MORE PERSISTENT UPPER RIDGE OVER THE WEST AND IN  
TURN SOMEWHAT STRONGER AND SLIGHTLY WESTWARD DIGGING OF SHORTWAVE  
ENERGY (WHICH IS FINALLY REACHING NORTHWESTERN NORTH AMERICA  
TODAY) INTO THE EAST. YET TO BE RESOLVED IS EXACTLY WHEN AND WHERE  
EASTERN ENERGY CLOSES OFF AN UPPER LOW, WITH 12Z/18Z GFS RUNS  
DOING SO A BIT LATER/NORTHEASTWARD THAN OTHER MODELS. IN THE NEW  
00Z CYCLE THE CMC HAS DEVIATED SIGNIFICANTLY FROM OTHER GUIDANCE  
OVER THE EASTERN PACIFIC, LEADING TO QUESTION MARKS IN ITS  
FORECAST FARTHER EASTWARD--SPECIFICALLY A STORM TRACK A BIT TO THE  
EAST OF CONSENSUS VERSUS MULTIPLE PRIOR RUNS THAT WERE ON THE  
WESTERN SIDE. SOME IMPORTANT FINE-SCALE DETAILS WILL STILL TAKE A  
WHILE TO BE RESOLVED SATISFACTORILY. A MULTI-MODEL BLEND WITH SOME  
MANUAL ENHANCEMENT TO MAINTAIN CONTINUITY IN DEPTH ALSO PROVIDED  
REASONABLE CONSISTENCY FOR A TRACK JUST OFFSHORE NEW ENGLAND.  
 
THE RELATIVELY SMALL AND WEAK NATURE OF THE UPPER LOW THAT MAY  
TRACK INTO THE SOUTHWEST THIS WEEKEND COULD STILL LEAD TO  
PREDICTABILITY ISSUES FOR A WHILE. TRENDS OVER THE PAST DAY HAVE  
BEEN SLOWER, DELAYING THE DEVELOPMENT OF ANY POTENTIAL  
PRECIPITATION ALONG AND NORTH OF THE GULF COAST. THE NEW 00Z ECMWF  
HAS TRENDED FASTER THOUGH. THERE IS STILL A WIDE ARRAY OF POSSIBLE  
TRACKS AFTER EMERGING FROM THE SOUTHWEST EARLY NEXT WEEK, WITH GFS  
RUNS TENDING TO BE THE FARTHEST NORTH AND THUS DRIEST.  
 
THE UPPER TROUGH EVENTUALLY REACHING INTO THE WESTERN U.S. WILL BE  
FROM SOME COMBINATION OF PROGRESSIVE NORTH PACIFIC ENERGY AND FLOW  
DESCENDING FROM ALASKA. DIFFERENCES BY DAY 7 TUESDAY ARE WITHIN  
THE REALM OF TYPICAL GUIDANCE SPREAD/ERROR AT THAT TIME FRAME BUT  
DEPEND IN PART ON WHETHER THERE IS A BREAK IN PACIFIC AND  
ALASKA/SIBERIA UPPER RIDGING (GFS/GEFS KEEP IT CONNECTED, MOST  
OTHER GUIDANCE SHOWS A BREAK), AN ISSUE THAT CAN ULTIMATELY LEAD  
TO MORE SIGNIFICANT DIFFERENCES OVER THE LOWER 48.  
 
THE AFOREMENTIONED MODEL BLEND USED FOR THE WESTERN ATLANTIC STORM  
WORKED WELL ELSEWHERE FOR THE FIRST HALF OF THE PERIOD AS WELL.  
THE FORECAST THEN TRANSITIONED TOWARD HALF MODELS/HALF MEANS BY  
LATE IN THE PERIOD TO RESOLVE SOME OF THE TIMING AND DETAIL  
DIFFERENCES THAT ARISE.  
   
..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. WHILE UNCERTAINTY CONTINUES  
WITH THE TRACK AND INTENSITY OF THIS SYSTEM, IT IS BECOMING MORE  
LIKELY THAT IT WILL BRING SIGNIFICANT SNOW, SLEET, AND FREEZING  
RAIN TO THE REGION, INCLUDING THE I-95 METROPOLITAN AREAS.  
HAZARDOUS TRAVEL CONDITIONS ARE POSSIBLE DUE TO THE COMBINATION OF  
SNOW, SLEET, FREEZING RAIN, AND WIND. CLOSE TO THE IMMEDIATE  
ATLANTIC COASTLINE, STRONG WINDS COMBINED WITH HIGH ASTRONOMICAL  
TIDES MAY LEAD TO COASTAL FLOODING. PLEASE CONTINUE TO MONITOR FOR  
FUTURE UPDATES AS THIS SYSTEM DEVELOPS.  
 
CURRENTLY IT APPEARS THAT THE UPPER TROUGH/LOW THAT MAY TRACK INTO  
CALIFORNIA AND THE SOUTHWEST THIS WEEKEND COULD 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. CONFIDENCE IS VERY LOW GIVEN A WIDE ARRAY  
OF POSSIBILITIES BETWEEN MEANINGFUL AMOUNTS AND DRY CONDITIONS.  
AHEAD OF THE NORTHEASTERN PACIFIC UPPER TROUGH, MOISTURE SHOULD  
BEGIN TO MOVE INTO THE NORTHWEST ON SUNDAY AND THEN CONTINUE TO  
SPREAD ACROSS MORE OF THE WEST WITH TIME. HIGHEST TOTALS OF  
RAIN/MOUNTAIN SNOW SHOULD BE OVER THE PACIFIC NORTHWEST. A SERIES  
OF WAVES/FRONTS MAY BRING EPISODES OF LIGHT AND SCATTERED SNOW  
INTO PARTS OF THE GREAT LAKES.  
 
MUCH OF THE EASTERN HALF OF THE COUNTRY WILL BE QUITE CHILLY  
THROUGH THE WEEKEND, WITH SATURDAY-SUNDAY HAVING THE BROADEST  
COVERAGE OF TEMPERATURES 10-20F BELOW NORMAL. EXPECT A WARMING  
TREND TO BRING READINGS BACK CLOSE TO NORMAL BY MONDAY OR TUESDAY.  
MUCH OF THE PLAINS WILL SEE ABOVE NORMAL TEMPERATURES (UP TO PLUS  
10-20F ANOMALIES) LATE THIS WEEK INTO MONDAY, ASIDE FROM A COOL  
FRIDAY OVER FAR SOUTHERN AREAS. NORTHERN LOCATIONS WILL SEE A  
COLDER TREND MONDAY-TUESDAY WHILE THE RELATIVE WARMTH FARTHER  
SOUTH SPREADS A BIT FARTHER EASTWARD. THE WEST SHOULD SEE PLUS  
5-10F OR SO ANOMALIES THROUGH THE WEEKEND FOLLOWED BY A COOLER  
TREND EARLY NEXT WEEK AS UPPER TROUGHING MOVES IN.  
 
RAUSCH/SCHICHTEL  
 
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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