113  
FXUS02 KWBC 242028  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
327 PM EST MON JAN 24 2022  
 
VALID 12Z THU JAN 27 2022 - 12Z MON JAN 31 2022  
 
...WINTER COASTAL STORM THREAT FROM THE MID-ATLANTIC TO ESPECIALLY  
NEW ENGLAND FRIDAY/WEEKEND...  
 
   
..OVERVIEW
 
 
GUIDANCE STILL SHOWS A MEAN UPPER LEVEL PATTERN THAT FEATURES  
TROUGHING OVER THE EAST, VARYING DEGREES OF RIDGING OVER THE WEST,  
AND A DEVELOPING NORTHEASTERN PACIFIC TROUGH THAT MAY APPROACH THE  
WEST COAST EARLY NEXT WEEK. WITHIN THIS AGREEABLE REGIME THERE ARE  
LINGERING UNCERTAINTIES REGARDING SPECIFICS OF AN EASTERN U.S.  
AMPLIFIED TROUGH THAT HAS BECOME MORE LIKELY 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, AS WELL AS FOR A LEAD PACIFIC SHORTWAVE APPROACHING  
THE WEST COAST BY SAT. THERE ARE ALSO LINGERING DIFFERENCES WITH  
DETAILS OF A LATER PERIOD NORTHEASTERN PACIFIC TROUGH, AFFECTING  
HOW MUCH MOISTURE REACHES THE NORTHWEST. HOWEVER, THESE  
DIFFERENCES ARE NOW LESS PROFOUND THAN EARLIER.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
EVEN THOUGH THE LARGE SCALE PATTERN EVOLUTION HAS BEEN RATHER  
CONSISTENT IN RECENT GUIDANCE, EMBEDDED AREAS OF UNCERTAINTY  
INVOLVE ASPECTS THAT ARE SMALLER IN SCALE AND HAVE LEAD TO LOWER  
PREDICTABILITY. HOWEVER, FORECAST SPREAD HAS DECREASED WITH THE  
LATEST COUPLE MODEL AND ENSEMBLE RUNS WHOSE SYSTEMS ARE NOW BETTER  
CLUSTERED, BOLSTERING FORECAST CONFIDENCE. THE WPC MEDIUM RANGE  
PRODUCT SUITE WAS MAINLY DERIVED FROM A COMPOSITE BLEND OF THE  
GFS/ECMWF/CANADIAN DAY 3-5 (THU-SAT) ALONG WITH SUPPORTIVE  
ENSEMBLES AND THE NATIONAL BLEND OF MODELS BEFORE TRANSITIONING TO  
JUST THE GEFS/ECMWF ENSEMBLE MEANS AND NBM INTO DAY 6/7 (SUN/MON).  
I DID APPLY SOME MANUAL ADJUSTMENTS TO OFFSET COMPOSITE SMOOTHING.  
THESE WERE PRIMARILY TO ENSURE SUFFICIENT COASTAL STORM DEPTH  
CONSISTENT WITH OVERALL SUPPORT, TRENDING DEEPER THAN WPC  
CONTINUITY GIVEN IMPROVED FORECAST CLUSTERING, ENSEMBLE MEMBER  
PROBABILITIES, AND A DEEPER/CLOSER TRACK TO THE COAST GUIDANCE  
TRENDS.  
 
   
..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.  
 
ELSEWHERE, SOME LOCATIONS NEAR THE WEST COAST MAY SEE AN INCREASE  
IN PRECIPITATION WITH AN APPROACHING SHORTWAVE/POSSIBLE COMPACT  
UPPER LOW LATE WEEK INTO THE WEEKEND. THIS ENERGY SHOULD  
EVENTUALLY SUPPORT SOME PRECIPITATION OVER THE SOUTHERN  
PLAINS/WESTERN HALF OF THE GULF COAST EARLY NEXT WEEK. FLOW AHEAD  
OF A NORTHEASTERN PACIFIC UPPER TROUGH SHOULD BRING RAIN AND  
MOUNTAIN SNOW INTO THE NORTHWEST INTO EARLY NEXT WEEK. A WAVY  
FRONTAL SYSTEM SHOULD ALSO BRING MOSTLY LIGHT SNOW TO THE GREAT  
LAKES AND APPALACHIANS LATE THIS WEEK. ONE OR MORE TRAILING WEAK  
WAVES MAY ALSO PRODUCE SCATTERED LIGHT SNOW OVER AREAS FROM THE  
EXTREME NORTHERN TIER INTO THE GREAT LAKES.  
 
MAINLY THE EAST WILL EXPERIENCE PERIODS WITH MUCH BELOW NORMAL  
TEMPERATURES (10-20F BELOW NORMAL). MUCH OF THE WEST SHOULD  
CONTINUE TO SEE MODERATELY ABOVE NORMAL TEMPERATURES (5-10F+  
ANOMALIES) WHILE THE NORTHERN AND CENTRAL PLAINS WILL LIKELY SEE  
MULTIPLE WARM DAYS WITH TEMPERATURES 10-20F ABOVE NORMAL,  
ESPECIALLY STARTING THE WEEKEND.  
 
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  
 
HAZARDS:  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND  
THE NORTHERN GREAT BASIN, SUN-MON, JAN 30-JAN 31.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHEAST, SAT, JAN  
29.  
- HEAVY RAIN ACROSS PORTIONS OF THE PACIFIC NORTHWEST, SUN-MON,  
JAN 30-JAN 31.  
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL APPALACHIANS, FRI, JAN  
28.  
- HEAVY SNOW ACROSS PORTIONS OF THE MID-ATLANTIC AND THE  
NORTHEAST, SAT, JAN 29.  
- HIGH WINDS ACROSS PORTIONS OF THE NORTHEAST, SAT, JAN 29.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE  
MID-ATLANTIC, THE LOWER MISSISSIPPI VALLEY, THE CENTRAL  
APPALACHIANS, THE TENNESSEE VALLEY, THE NORTHEAST, THE SOUTHERN  
APPALACHIANS, THE SOUTHEAST, THE GREAT LAKES, AND THE OHIO VALLEY,  
SAT-SUN, JAN 29-JAN 30.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE MIDDLE  
MISSISSIPPI VALLEY, THE GREAT LAKES, AND THE UPPER MISSISSIPPI  
VALLEY, FRI-SAT, JAN 28-JAN 29.  
- HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF THE  
MID-ATLANTIC AND THE NORTHEAST, SAT, JAN 29.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE AND  
MAINLAND ALASKA, THU-FRI, JAN 27-JAN 28.  
- HIGH WINDS ACROSS PORTIONS OF THE ALASKA PANHANDLE AND MAINLAND  
ALASKA, THU-FRI, JAN 27-JAN 28.  
 
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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