138  
FXUS02 KWBC 182018  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
317 PM EST TUE JAN 18 2022  
 
VALID 12Z FRI JAN 21 2022 - 12Z TUE JAN 25 2022  
 
...HEAVY SNOW/ICE THREAT FOR THE SOUTHEAST/MID-ATLANTIC/NORTHEAST  
INTO FRIDAY/SATURDAY...  
   
..OVERVIEW
 
 
ARCTIC HIGH PRESSURE WILL PUSH A COLD FRONT THROUGH THE DEEP SOUTH  
AND EAST LATER THIS WEEK, LEADING TO MUCH BELOW NORMAL  
TEMPERATURES. MOIST AIR FED INTO THE SOUTHERN AND EASTERN  
PERIPHERY OF THE COLD AIRMASS IS INCREASINGLY LIKELY TO FUEL A  
HEAVY SNOW/ICE THREAT FROM THE SOUTHEAST TO THE MID-ATLANTIC INTO  
FRI. POTENTIAL COASTAL STORM DEVELOPMENT WOULD ENHANCE MID-ATLANIC  
TO NORTHEAST HEAVY SNOW POTENTIAL SAT. MEANWHILE, UPPER RIDGING  
BUILDS OFF/ALONG THE WEST COAST AS DIGGING INTERMOUTAIN  
WEST/ROCKIES SHORTWAVE ENERGY SPILLS SNOWS SOUTHWARD IN ROUTE TO  
PRODUCING A SOUTHWEST CLOSED LOW BY THE WEEKEND SLATED TO EJECT  
ACROSS THE U.S. SOUTHERN TIER EARLY NEXT WEEK.  
 
...GUIDANCE/PREDICTABILITY ASSESSMENT AND WEATHER  
HIGHLIGHTS/THREATS...  
 
GUIDANCE REMAINS IN DECENT AGREEMENT WITH THE LARGE SCALE MEAN  
FLOW OVER THE LOWER 48 HIGHLIGHTED BY AN UPPER RIDGE OFF/ALONG THE  
WEST COAST AND UPPER TROUGHING OVER THE CENTRAL AND EASTERN U.S..  
HOWEVER, THE MODELS HAVE RECENTLY BEEN HORRENDOUS WITH RUN TO RUN  
CONTINUITY WITH EMBEDDED SHORTWAVES THAT DIG THROUGH THE MEAN  
UPPER TROUGH POSITION. IN PARTICULAR, FORECAST SPREAD REMAINS A  
SIGNIFICANT TIMING AND AMPLITUDE ISSUE WITH A MAIN SHORTWAVE OVER  
THE EAST-CENTRAL TO EASTERN STATES FRI/SAT THAT PRODUCES MAJOR  
PLACEMENT DIFFERENCES WITH A POTENTIALLY IMPACTFUL COASTAL LOW  
GENESIS IN THE WESTERN ATLANTIC. THE 12Z ECMWF IS FASTER AND MORE  
NORTHERLY THAN LAST NIGHTS 00Z RUN. THIS IS CONSISTENT WITH ITS  
CURRENT TREND. THE 12Z GFS IS CONSIDERABLY MORE PROGRESSIVE THAN  
THE 12Z ECMWF/UKMET/CMC SUITE, BUT CONSISTENT WITH ITS 00Z  
PREDECESSOR WITH ITS SOLUTION PLACING THE SHORTWAVE AXIS FARTHER  
NORTH THAN THE OTHER DETERMINISTICS.  
 
THERE IS POTENTIAL FOR HEAVY SNOW, SLEET, AND FREEZING RAIN  
PARTICULARLY FROM THE SOUTHERN APPALACHIANS AND  
CAROLINAS/MID-ATLANTIC INTO FRI, POTENTIALLY INTO THE NORTHEAST BY  
SAT. THE PATTERN WILL ALSO BE FAVORABLE FOR LAKE EFFECT SNOW GIVEN  
THE ARCTIC AIRMASS IN PLACE. INTO EARLY NEXT WEEK, GUIDANCE AGREES  
TO HOLD AN AMPLIFIED MEAN UPPER TROUGH OVER THE COOLED  
EAST-CENTRAL U.S., ABLEIT WITH VARIATIONS WITH EMBEDDED SHORTWAVES  
SET TO DIG AND REINFORCED THE FEATURE UNDERNEATH A DEEP LOW  
CENTERED JUST EAST OF THE HUDSON BAY.  
 
MEANWHILE OUT WEST, MODELS GENRALLY AGREE TO DIG SHORTWAVE ENERGY  
SOUTHWARD ACROSS THE INTERMOUNTAIN WEST FRIDAY LEADING TO A  
SOUTHWEST U.S/NORTHERN MEXICO CLOSED LOW BY THE WEEKEND. LEAD FLOW  
RESPONSE IN ADVANCE OF EXPECTED SYSTEM EJECTION OUT ACROSS THE  
U.S. SOUTHERN TIER EARLY NEXT WEEK WOULD SUPPORT A MODEST SWATH OF  
OVERRUNNING PRECIPITATION WITHIN A COOLED AIRMASS FROM TEXAS  
EASTWARD ACROSS THE GULF COAST. THE BEST CHANCE FOR SNOW WILL  
FRI/SAT DOWN THROUGH THE ROCKIES AS THE SHORTWAVE IMPULSE MOVES  
THROUGH. OTHER THAN THAT, CONDITIONS SHOULD REMAIN MOSTLY DRY,  
WITH SLIGHTLY WARMER THAN NORMAL CONDITIONS FOR THE WEST COAST  
STATES UNDERNEATH THE RIDGE, AND ABOVE NORMAL TEMPERATURES ARE  
THEN EXPECTED FOR THE HIGH PLAINS EARLY NEXT WEEK.  
 
KEBEDE/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 SNOW ACROSS PORTIONS OF THE SOUTHEAST, THE SOUTHERN  
APPALACHIANS, THE MID-ATLANTIC, AND THE  
CENTRAL APPALACHIANS, FRI-SAT, JAN 21-JAN 22.  
- FREEZING RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE  
MID-ATLANTIC, THE SOUTHERN APPALACHIANS, AND  
THE TENNESSEE VALLEY, FRI-SAT, JAN 21-JAN 22.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER  
MISSISSIPPI VALLEY.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE LOWER MISSISSIPPI  
VALLEY, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE  
SOUTHEAST, AND THE SOUTHERN  
PLAINS, FRI-SUN, JAN 21-JAN 23.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE LOWER MISSISSIPPI  
VALLEY, THE TENNESSEE VALLEY, THE GREAT LAKES, THE MIDDLE  
MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI  
VALLEY, THE SOUTHERN PLAINS, AND THE OHIO VALLEY, FRI, JAN 21.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE MIDDLE MISSISSIPPI  
VALLEY, THE GREAT LAKES, THE UPPER MISSISSIPPI VALLEY, AND THE  
NORTHERN PLAINS, SUN-TUE, JAN 23-JAN  
25.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHEAST,  
THE CENTRAL APPALACHIANS, THE  
MID-ATLANTIC, THE SOUTHERN APPALACHIANS, THE GREAT LAKES, AND THE  
OHIO VALLEY, FRI-SAT, JAN 21-JAN  
22.  
 
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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