308  
FXUS02 KWBC 170449  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1149 PM EST SUN JAN 16 2022  
 
VALID 12Z THU JAN 20 2022 - 12Z MON JAN 24 2022  
 
...COOLED DEEP SOUTH TO EAST COAST SNOW/ICE THREATS WITH UNCERTAIN  
WAVE GENESIS PATTERN...  
 
...GUIDANCE/PREDICTABILITY ASSESSMENT AND WEATHER  
HIGHLIGHTS/HAZARDS...  
 
MAJOR MODEL DIFFERENCES PERSIST IN A DATA SENSITIVE PATTERN WITH  
RAMPANT RUN TO RUN CONTINUITY ISSUES DAYS 3-7. INSTEAD OF CHASING  
UNCERTAIN SHORTWAVES, THE WPC MEDIUM RANGE PRODUCT SUITE WAS  
PRIMARILY DERIVED FROM THE 01 UTC NATIONAL BLEND OF MODELS AND A  
COMPOSITE BLEND OF THE 18 UTC GEFS/12 UTC ECMWF ENSEMBLE MEANS  
WHOSE REASONABLY COMPATIBLE SOLUTIONS LESSEN DETAIL CONSISTENT  
WITH A PATTERN WITH LOWER THAN NORMAL EMBEDDED SYSTEM  
PREDICTABILITY. MANUAL ADJUSTMENTS WERE APPLIED TO INCORPORATE AS  
MUCH WPC SYSTEM CONTINUITY AS FEASIBLE.  
   
..PATTERN OVERVIEW AND WEATHER HIGHLIGHTS/THREATS
 
 
A DEEPENED LOW AND WRAPPING SNOWS/WINDS IS SLATED TO EXIT THE  
NORTHEAST DAY 3/THU AS A MASSIVE ARCTIC HIGH SPREADS ACROSS MUCH  
OF THE CENTRAL AND EASTERN CONUS. COLD AIR FLOW ALSO FAVOR LAKE  
EFFECT SNOW. A CONTINUING SERIES OF UNCERTAIN IMPULSES WILL CARVE  
OUT AND REINFORCE THE LARGE MEAN UPPER TROUGH OVER THE CENTRAL AND  
EASTERN U.S. THROUGH THIS FORECAST PERIOD, DIGGING DOWNSTREAM OF  
AN AMPLIFIED UPPER RIDGE POSITION JUST OFFSHORE THE WEST COAST.  
THIS PATTERN WILL BE CONDUCIVE FOR PERIODS WITH SNOW TO SPREAD  
ACROSS THE NORTHERN AND CENTRAL ROCKIES THU/FRI, AND BEYOND THAT  
FOR UNCERTAIN PERIODS OF SHORTWAVE/FRONTAL WAVE ENHANCED  
PRECIPITATION TO SPAN FROM TEXAS/WESTERN GULF COAST THROUGH THE  
DEEP SOUTH AND SOUTHEAST TO THE MID-ATLANTIC/EAST COAST. THIS  
INCLUDES THREATS FOR SNOW/ICE ON THE NORTHERN PERIPHERY OF  
ACTIVITY ACROSS THE SOUTH/SOUTHEAST AND POTENTIALLY UP THE  
APPALACHIANS/EAST COAST TO THE U.S. NORTHERN TIER/NORTHEAST GIVEN  
THE EXTENT OF COLD AIR INTRUSIONS AND WITH UNCERTAIN SYSTEMS  
ROTATING THROUGH THE MEAN UPPER TROUGH POSITION. HOWEVER, AMPLE  
FORECAST SPREAD AND CONTINUITY ISSUES LIMITS PREDICTABILITY OF  
PARTICULAR SYSTEM THREATS DAYS 4-7.  
 
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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