311  
FXUS02 KWBC 010707  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
207 AM EST TUE FEB 01 2022  
 
VALID 12Z FRI FEB 04 2022 - 12Z TUE FEB 08 2022  
 
...HEAVY SNOWFALL BEGINNING TO EXIT NORTHERN NEW ENGLAND BY THE  
START OF THE MEDIUM RANGE PERIOD...  
 
   
..OVERVIEW
 
 
A POSITIVELY TILTED AND REINFORCED MEAN TROUGH ALOFT SHOULD HOLD  
STRONG ACROSS MUCH OF THE CONUS THROUGH THE MEDIUM RANGE PERIOD  
(FRIDAY-TUESDAY), AS STRONG UPPER RIDING BUILDS OVER BOTH THE  
WESTERN ATLANTIC AND THE EASTERN PACIFIC (AND PERIODICALLY  
EXTENDING INTO PARTS OF THE WEST). ON FRIDAY, A SHORTWAVE MOVING  
THROUGH THE NORTHEAST WILL DRIVE A POTENT COLD FRONT OFF THE EAST  
COAST, WITH POTENTIALLY HEAVY WINTRY PRECIP LIKELY COMING TO AN  
END ON THE NORTH SIDE OF THIS SYSTEM. MEANWHILE, THE NEXT  
SHORTWAVE/POSSIBLY BRIEF CLOSED LOW WILL WEAKEN AS IT MOVES OVER  
THE SOUTHERN PLAINS, AND COMBINE WITH ENERGY TO THE NORTH. THIS  
WEEKEND, UNCERTAINTY BEGINS TO INCREASE OVER DETAILS OF ADDITIONAL  
SHORTWAVES DROPPING DOWN THE EAST SIDE OF THE RIDGE IN THE WEST  
(WITH SOME GUIDANCE SUPPORT FOR A SOUTHWEST CLOSED LOW  
SUNDAY-TUESDAY) AS WELL AS A SERIES OF NORTHERN STREAM SHORTWAVES  
WHICH SHOULD SUPPORT A TRAIN OF NORTHERN TIER WAVES INTO EARLY  
NEXT WEEK. TROUGHING ACROSS THE EAST BY NEXT TUESDAY MAY INDUCE  
LOW PRESSURE OFF THE EAST COAST, BUT MOST GUIDANCE AT THIS TIME  
SHOWS IT TRACKING WELL ENOUGH EAST FOR AVOID ANY IMPACTS ALONG THE  
COAST.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
A GENERAL BLEND OF 12Z/18Z MODEL GUIDANCE FROM YESTERDAY PROVIDED  
A GOOD REPRESENTATION OF CONSENSUS FOR DAYS 3-4 FRIDAY-SATURDAY.  
IN THIS TIME FRAME, FRONTAL WAVES ALONG THE COLD FRONT IN THE EAST  
SHOULD CONSOLIDATE INTO A SINGLE LOW THAT ULTIMATELY TRACKS AWAY  
FROM NEW ENGLAND WHILE A WEAK WAVE AND FRONTAL SYSTEM REACH THE  
NORTHERN TIER. THERE REMAIN SOME MINOR NORTH-SOUTH DIFFERENCES IN  
COLD FRONTAL PLACEMENT EARLY FRIDAY, BUT MOSTLY JUST THE TYPICAL  
RUN-TO-RUN MODEL FLUCTUATIONS. THE GFS HAS BEEN CONSISTENT THE  
PAST SEVERAL RUNS IN A LITTLE FARTHER SOUTHWARD PUSH OF THE  
FRONT/COLDER AIR, WHICH ULTIMATELY WOULD BRING WINTRY  
PRECIPITATION FARTHER SOUTH INTO PARTS OF THE MID-ATLANTIC ON  
FRIDAY. THE LAST FEW RUNS OF THE ECMWF (INCLUDING THE NEW 00Z RUN  
FOR TODAY) HAS BEEN SHIFTING EVER SO SLIGHTLY SOUTHWARD THOUGH AS  
WELL SO EVEN THOUGH THE GFS SEEMS TO BE A COLD OUTLIER RIGHT NOW,  
IT CANNOT BE COMPLETELY RULED OUT.  
 
BY THIS WEEKEND, THE GREATEST POINT OF UNCERTAINTY CONTINUES TO BE  
WITH A SHORTWAVE DROPPING INTO THE NORTHWEST AND A POTENTIAL BREAK  
OFF OF SOUTHERN STREAM ENERGY ULTIMATELY RESULTING IN A CLOSED LOW  
LINGERING OVER/NEAR THE SOUTHWEST. THE GFS HAS BEEN VERY  
CONSISTENT WITH A MUCH STRONGER/DEEPER CLOSED LOW, WHILE THE REST  
OF THE GUIDANCE SUPPORTS A LITTLE BIT MORE CONSOLIDATION BETWEEN  
NORTHERN/SOUTHERN STREAM ENERGY THROUGH THE ROCKIES INTO THE  
CENTRAL PLAINS. AT THIS POINT, THE GFS IS A BIG OUTLIER, BUT DOES  
HAVE SUPPORT FROM SOME ENSEMBLE MEMBERS (AND OLDER RUNS OF THE  
ECMWF). WPC PREFERS THE WEAKER SOLUTION AS OFFERED BY THE  
DETERMINISTIC ECMWF/CMC AND ENSEMBLE MEANS, LEANING AWAY FROM THE  
MUCH TOO DEEP GFS.  
 
FOR NORTHERN STREAM SHORTWAVES/FRONTAL WAVES, JUST MAINLY MINOR  
TIMING DIFFERENCES THROUGH THE WEEKEND EASILY HANDLED BY A GENERAL  
MODEL BLEND. ONE POINT OF CONCERN IS EVOLUTION/INTERACTION OF LATE  
PERIOD NORTHERN/SOUTHERN STREAM ENERGY TO INDUCE SURFACE LOW  
DEVELOPMENT OFF THE EAST COAST. THE 12Z/YESTERDAY ECMWF BROUGHT  
THIS LOW MUCH CLOSER TO THE EAST COAST THAN MOST OTHER GUIDANCE,  
BUT THE 00Z RUN SEEMS TO HAVE TRENDED FARTHER OFFSHORE AGAIN, AND  
MORE INLINE WITH THE ENSEMBLE MEANS. GIVEN THE INCREASING LATE  
PERIOD DETAIL DIFFERENCES ACROSS THE BOARD, THE WPC FORECAST  
LEANED FAIRLY HEAVILY ON THE ENSEMBLE MEANS.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
TROUGHING INTO THE OHIO VALLEY/NORTHEAST ON FRIDAY AND A LEADING  
WAVY COLD FRONT THROUGH THE EAST WILL CONTINUE THE THREAT FOR  
POTENTIALLY SIGNIFICANT SNOWS ACROSS MAINLY NORTHERN NEW ENGLAND  
ON FRIDAY. THERE LIKELY WILL BE A BAND OF MODERATE TO HEAVY  
SLEET/FREEZING RAIN JUST TO THE SOUTH OF THIS IN THE TRANSITION  
ZONE AS WELL, WITH LINGERING UNCERTAINTIES ON HOW FAR SOUTH IT  
EXTENDS (POSSIBLY INTO PARTS OF THE MID-ATLANTIC). HEAVY RAINFALL  
ACROSS THE SOUTH AT THE END OF THE SHORT RANGE PERIOD WILL MOSTLY  
HAVE ENDED BY FRIDAY MORNING AS THE BETTER MOISTURE FEED GETS CUT  
OFF FROM THE GULF. SOME LINGERING, MODERATELY TO LOCALLY HEAVY  
SHOWERS, ARE STILL POSSIBLE ACROSS PARTS OF THE SOUTHEAST ALONG  
THE COLD FRONT.  
 
ELSEWHERE, NORTHERN TIER SYSTEMS MAY PRODUCE A COUPLE EPISODES OF  
LIGHT AND SCATTERED SNOWFALL. MOSTLY LIGHT RAIN/MOUNTAIN SNOW  
SHOULD ACCOMPANY A COUPLE SYSTEMS BRUSHING THE PACIFIC NORTHWEST  
AND POSSIBLY EXTENDING INTO THE NORTHERN ROCKIES. SIGNIFICANT  
GUIDANCE DIFFERENCES WITH SEPARATE STREAMS OF ENERGY ALOFT LEAD TO  
LOW CONFIDENCE IN THE COVERAGE AND AMOUNTS OF PRECIPITATION OVER  
THE SOUTH AND EAST FROM THE WEEKEND INTO THE START OF NEXT WEEK.  
SOME PRECIPITATION TYPE ISSUES MAY COME INTO PLAY DEPENDING ON HOW  
FAR NORTH THE MOISTURE SHIELD EXTENDS.  
 
AREAS AHEAD OF THE EASTERN U.S. COLD FRONT WILL CONTINUE TO SEE  
ABOVE AVERAGE (+10-15F) ANOMALIES FOR HIGHS, WITH MORE ANOMALOUS  
OVERNIGHT MORNING LOWS ON FRIDAY. ARCTIC HIGH PRESSURE SETTLING  
ACROSS THE CENTRAL U.S. AND INTO THE MIDWEST BEHIND THE FRONT WILL  
BRING VERY COLD TEMPS TO ESPECIALLY PARTS OF THE SOUTHERN PLAINS  
WHERE DAYTIME HIGHS 20-25 DEGREES BELOW NORMAL ARE POSSIBLE.  
POINTS NORTH AND EAST SHOULD BE SLIGHTLY LESS EXTREME THROUGH  
STILL AREAS OF GENERALLY -10-20F HIGHS. TEMPERATURES SHOULD  
MODERATE AND SLIDE EASTWARD THIS WEEKEND, WITH MANY PLACES EAST OF  
THE PLAINS BACK TO NEAR NORMAL VALUES BY EARLY NEXT WEEK. UPPER  
RIDGING TRYING TO BUILD ACROSS THE NORTHERN/CENTRAL PLAINS  
MONDAY-TUESDAY OF NEXT WEEK COULD BRING A PERIOD OF MUCH ABOVE  
NORMAL TEMPERATURES TO THIS REGION. THE WEST COAST STATES SHOULD  
BE NEAR NORMAL INTO WEEKEND, TRENDING SLIGHTLY WARMER THE REST OF  
THE PERIOD OWING TO AMPLIFIED RIDGING ACROSS THE EAST PACIFIC.  
 
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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