060  
FXUS02 KWBC 090706  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
205 AM EST SUN JAN 09 2022  
 
VALID 12Z WED JAN 12 2022 - 12Z SUN JAN 16 2022  
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD WILL BEGIN ON WEDNESDAY WITH GENERAL  
RIDGING OVER THE WESTERN U.S. ATOP A CLOSED SOUTHERN STREAM LOW  
NEAR BAJA CALIFORNIA, WHILE BROAD TROUGHING EJECTS DISTURBANCES  
EASTWARD OVER THE NORTH-CENTRAL AND EASTERN U.S. DURING THE  
PERIOD. THE SOUTHERN STREAM LOW/TROUGH SHOULD TRACK EASTWARD  
LIKELY BY LATE THURSDAY/FRIDAY AND SPREAD INCREASING PRECIPITATION  
CHANCES FROM THE FOUR CORNERS STATES INTO THE SOUTH-CENTRAL U.S.,  
WHICH BY THE WEEKEND COULD SPREAD INTO THE EAST AHEAD OF AN UPPER  
TROUGH THAT MAY CONSOLIDATE IN THE CENTRAL CONUS.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
MODEL AGREEMENT REMAINS REASONABLY GOOD FOR THE EARLY PART OF THE  
PERIOD WEDNESDAY, BUT THIS CONSENSUS QUICKLY DEVOLVES BY  
THURSDAY-FRIDAY AS A FEW FEATURES OF CONCERN SHOW LOW  
PREDICTABILITY. FIRST, THERE ARE SOME DIFFERENCES AMONG MODELS  
WITH THE POSITION OF THE INITIAL PACIFIC UPPER LOW WEDNESDAY, BUT  
THERE IS AT LEAST A CONSENSUS WITH THE 12Z GFS/ECWMF/CMC IN GOOD  
AGREEMENT, THOUGH ESPECIALLY THE 12Z UKMET AND TO SOME EXTENT THE  
18Z GFS WERE CENTERED FARTHER SOUTHWEST. THE 12Z UKMET SHOWS THE  
FEATURE BASICALLY ERODING IN PLACE ON THURSDAY RATHER THAN  
TRACKING EASTWARD INLAND, WHICH IS NOT FAVORED AT THIS TIME, AS  
OTHER GUIDANCE (EXCEPT THE CURRENTLY INCOMING 00Z ECMWF) SHOWS THE  
ENERGY MOVING ACROSS THE FOUR CORNERS AND SOUTHERN PLAINS, THOUGH  
TIMING VARIES A BIT. UPSTREAM, MORE DISAGREEMENT ARISES WITH THE  
HANDLING OF THE NEXT PACIFIC TROUGH/UPPER LOW APPROACHING THE WEST  
COAST THURSDAY-FRIDAY. MOST GFS RUNS HAVE INDICATED A CLOSED LOW  
WITH THIS FEATURE AND A SLOWER TRACK TOWARDS THE WEST COAST, WITH  
RECENT RUNS SHOWING A NORTHEASTWARD TURN. MEANWHILE GUIDANCE SUCH  
AS THE 12Z/00Z CMC AND 12Z ECMWF HAVE AN OPEN SHORTWAVE THURSDAY  
THAT SPILLS ENERGY SOUTHEASTWARD INTO THE WEST BY FRIDAY, WHICH  
MAY BE MORE REASONABLE, BUT ENSEMBLE MEMBERS EXHIBITING A HUGE  
VARIETY IN HOW THIS ENERGY INTERACTS AND EVOLVES WITH THE FIRST  
FEATURE AND THE OVERALL RIDGING, SO CONFIDENCE IS LOW.  
 
MEANWHILE IN THE EAST, SHORTWAVES MOVING THROUGH THE BROAD TROUGH  
ALSO DISPLAY SOME VARIETY AMONG MODELS IN TERMS OF THEIR TRACK AND  
STRENGTH. ONE MAIN OUTLIER WAS THE 18Z GFS BY AROUND FRIDAY, WHICH  
CONSOLIDATED ENERGY TO CREATE A CLOSED MID-UPPER LOW IN THE  
WESTERN ATLANTIC AND THUS BROUGHT A DEEP SURFACE LOW/NOR'EASTER  
CLOSE TO THE EAST COAST. THIS TRACK CLOSE TO LAND IS NOT FAVORED  
AND NOT SUPPORTED BY INCOMING 00Z MODEL GUIDANCE EITHER. THEN A  
STRONG BOUT OF ADDITIONAL ENERGY COULD MAKE ITS WAY INTO THE  
MIDWEST ON SATURDAY AND EXPAND TROUGHING FARTHER SOUTH AS WELL,  
BUT WITH SOME VARIABILITY IN THE TROUGH AXIS AND THUS THE  
ASSOCIATED COLD FRONTAL TRACK AND AREAS OF POSSIBLE PRECIPITATION  
CHANCES FOR THE WEEKEND.  
 
THE WPC MEDIUM RANGE FORECAST BLEND WAS THUS BASED ON A BLEND OF  
THE 12/18Z GFS, 12Z ECMWF, AND 12Z CMC DETERMINISTIC GUIDANCE  
EARLY ON, PHASING OUT THE 18Z GFS BY DAY 5 AND LESSENING THE  
PROPORTION OF DETERMINISTIC MODELS IN FAVOR OF THE GEFS AND EC  
ENSEMBLE MEANS THAT DEMONSTRATED OKAY AGREEMENT, ALBEIT WITH  
WEAKER FEATURES AS USUAL. BY DAYS 6/7 USED 60% MEANS TO LESSEN  
INDIVIDUAL MODEL DIFFERENCES.  
   
..WEATHER HIGHLIGHTS
 
 
MODERATE TO HEAVY PRECIPITATION COULD CONTINUE ON WEDNESDAY IN THE  
FAVORED HIGHER ELEVATIONS OF THE OLYMPICS AND NORTHERN CASCADES,  
THOUGH THE HEAVIEST PRECIPITATION IS FORECAST OVER VANCOUVER  
ISLAND AS A WEAK ATMOSPHERIC RIVER TAKES AIM AT THE REGION.  
MEANWHILE, THE SOUTHERN STREAM PACIFIC UPPER LOW INFLUENCING THE  
SOUTHWEST WILL SPREAD PRECIPITATION TO THE FOUR CORNERS STATES AND  
THEN INTO THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY BY  
THURSDAY AND FRIDAY AS IT TRACKS INLAND AND A LOW PRESSURE/FRONTAL  
SYSTEM DEVELOPS. SHORTWAVES MOVING THROUGH THE NORTHERN STREAM  
COULD SPREAD LIGHT LAKE EFFECT/ENHANCED SNOW TO THE GREAT LAKES  
AROUND MIDWEEK, BUT CHANCES FOR WINTRY WEATHER COULD RAMP UP BY  
THE LATTER PART OF THE WEEK FOR THE MIDWEST/GREAT LAKES UNDERNEATH  
THE STRONGER SHORTWAVE ENERGY DROPPING THROUGH THE REGION. AS THE  
SPLIT FLOW APPEARS TO PHASE BY NEXT WEEKEND, PRECIPITATION SHOULD  
SPREAD TO THE EASTERN SEABOARD, WITH RAIN IN THE SOUTH AND THE  
POSSIBILITY FOR SNOW IN THE NORTHEAST, BUT WITH UNCERTAINTY IN THE  
DETAILS AT THIS TIME.  
 
AFTER A CHILLY DAY IN THE EASTERN SEABOARD ON WEDNESDAY,  
ESPECIALLY IN THE NORTHEAST WHERE LOWS WILL BE 10-20F BELOW  
AVERAGE, TEMPERATURES SHOULD MODERATE CLOSER TO NORMAL OR A BIT  
ABOVE THERE BY THE LATTER PART OF THE WEEK. THE CENTRAL U.S. WILL  
SEE CONSIDERABLY WARMER THAN NORMAL CONDITIONS, WITH A WIDESPREAD  
AREA IN THE PLAINS/MISSISSIPPI VALLEY SEEING HIGHS 10-20F ABOVE  
AVERAGE, EVEN WARMER IN LOCALIZED AREAS. MEANWHILE, LOWS WILL BE  
15-25F ABOVE NORMAL IN THE NORTHERN PLAINS. THEN BY NEXT WEEKEND,  
AS COOLER HIGH PRESSURE SYSTEMS BUILD IN BEHIND COLD FRONTS, HIGHS  
SHOULD BE RIGHT AROUND AVERAGE FOR THIS TIME OF YEAR IN MOST  
PLACES, WITH POCKETS THAT ARE A FEW DEGREES COOLER THAN NORMAL FOR  
HIGHS, WHILE LOWS SHOULD BE A FEW DEGREES MILDER THAN NORMAL IN  
THE EAST.  
 
TATE  
 
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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