926  
FXUS02 KWBC 070701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 AM EST FRI JAN 07 2022  
 
VALID 12Z MON JAN 10 2022 - 12Z FRI JAN 14 2022  
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD WILL BEGIN ON MONDAY WITH AN AMPLIFIED  
UPPER FLOW PATTERN WITH A TROUGH STEMMING SOUTHWARD FROM A DEEP  
UPPER LOW OVER EAST-CENTRAL CANADA AND RIDGING ACROSS THE WESTERN  
U.S. AND CANADA. A SPLIT FLOW PATTERN IS LIKELY TO DEVELOP ACROSS  
THE EASTERN PACIFIC AND WEST, AS A SOUTHERN STREAM LOW DROPS  
SOUTHWARD JUST WEST OF CALIFORNIA THROUGH THE EARLY PART OF THE  
WORKWEEK. MEANWHILE IN THE EAST, THE PATTERN MAY DEAMPLIFY  
SOMEWHAT BUT ROUNDS OF SHORTWAVE ENERGY WILL LIKELY TRACK THROUGH  
THE BROADER TROUGH AXIS.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
REASONABLY GOOD PREDICTABILITY EXISTS EARLY IN THE PERIOD AS MODEL  
GUIDANCE HAS REMAINED CONSISTENT AND AGREEABLE WITH THE DEEP UPPER  
TROUGH ACROSS THE EAST AND RIDGING ACROSS THE WEST. GUIDANCE FROM  
THE 12Z/18Z (YESTERDAY) CYCLE ALSO AGREES FAIRLY WELL WITH THE  
EXISTENCE OF ENERGY DROPPING SOUTHWARD THROUGH THE PACIFIC AND  
FORMING A CLOSED SOUTHERN SOUTHERN STREAM UPPER LOW, WITH  
GENERALLY SIMILAR TIMING TO THE PREVIOUS FORECAST CYCLE WITH IT  
MIGRATING SLOWLY AND STAYING WEST OF BAJA CALIFORNIA THROUGH EARLY  
WEDNESDAY. THE INCOMING 00Z MODEL GUIDANCE ALSO SHOWS A SIMILAR  
IDEA, THOUGH THE 00Z CMC HAS THE LOW STAYING OPEN FOR LONGER. THE  
UPPER LOW/TROUGH MAY FINALLY GET KICKED OUT BY THURSDAY AS  
ADDITIONAL PACIFIC ENERGY APPROACHES. HOWEVER, THE EVOLUTION OF  
THIS ENERGY AND ADDITIONAL NARROW RIDGING COMING IN BEHIND REMAIN  
UNCERTAIN WITH QUITE A BIT OF ENSEMBLE SPREAD, THOUGH THE RECENT  
GEFS AND EC ENSEMBLE MEANS DO SHOW HINTS OF THIS SHORTWAVE ENERGY  
NOW. AT THIS POINT, THE 12Z ECMWF AND CMC AND THE 18Z GFS (RATHER  
THAN THE 12Z GFS) SEEMED TO HAVE THE BEST AGREEMENT WITH THESE  
FEATURES, BUT WITH LOW CONFIDENCE. ADDITIONALLY, NORTHERN STREAM  
IMPULSES MOVING THROUGH THE MEAN CYCLONIC FLOW IN THE EAST SHOW  
SOME DIFFERENCES IN STRENGTH AND POSITION ESPECIALLY DURING THE  
SECOND HALF OF THE WEEK.  
 
THUS FOR THE WPC MEDIUM RANGE FORECAST, USED A BLEND OF THE  
DETERMINISTIC 12Z ECMWF/CMC AND 18Z GFS FOR THE EARLY PART OF THE  
PERIOD, THEN PHASED IN SOME 18Z GEFS AND 00Z EC ENSEMBLE MEAN  
GRADUALLY TO ABOUT 40% (60% OPERATIONAL MODELS) BY THE END OF THE  
PERIOD. THIS SERVED TO MINIMIZE INDIVIDUAL FORECAST DIFFERENCES  
BUT MAINTAIN SOME STRENGTH OF SYSTEMS, AND PROVIDED GOOD  
CONTINUITY WITH THE PREVIOUS FORECAST ON DAYS 3-6.  
   
..WEATHER HIGHLIGHTS
 
 
DRIER CONDITIONS ARE LIKELY OVER MUCH OF THE CONTIGUOUS U.S. FOR  
THE EARLY PART OF NEXT WORKWEEK AS LARGE SURFACE HIGHS INFLUENCE  
THE INTERMOUNTAIN WEST TO THE CENTRAL U.S. BEHIND A COLD FRONT.  
SHOWERS COULD LINGER OVER FLORIDA ON MONDAY AS THE FRONT PASSES  
THROUGH, WHILE GENERALLY WESTERLY FLOW CAUSES LAKE EFFECT SNOW  
DOWNWIND OF THE GREAT LAKES ESPECIALLY ON MONDAY, BUT WITH THE  
POSSIBILITY FOR ADDITIONAL ROUNDS AS THE WEEK PROGRESSES. THE  
PACIFIC NORTHWEST SHOULD SEE PERIODS OF PRECIPITATION AS FRONTS  
APPROACH THE AREA, WITH HIGHER TOTALS OVER TYPICAL UPSLOPE AREAS  
OF THE OLYMPICS AND CASCADES. THEN MOISTURE MAY SPREAD AHEAD OF  
THE UPPER LOW IN THE EASTERN PACIFIC INTO THE SOUTHWEST.  
PRECIPITATION TOTALS ARE EXPECTED TO BE LIGHT IN THE SOUTHWEST,  
BUT COULD INCREASE INTO THE SOUTHERN PLAINS AND LOWER MISSISSIPPI  
VALLEY BY WEDNESDAY AND THURSDAY AS THE LOW TRACKS EASTWARD AND  
ALSO DRAWS MOISTURE FROM THE GULF OF MEXICO. HOWEVER, CONFIDENCE  
IN THE DETAILS OF RAINFALL AMOUNTS IS SOMEWHAT LOW AND WILL LIKELY  
BE REFINED IN FUTURE FORECAST UPDATES.  
 
THE NEXT ROUND OF ARCTIC AIR WILL BE IN PLACE ACROSS THE NORTHERN  
PLAINS AND UPPER MIDWEST ON MONDAY, WITH TEMPERATURES OF 10-25F  
BELOW NORMAL AND MAXIMUM TEMPERATURES STAYING BELOW 0F IN SOME  
AREAS. BY TUESDAY THIS CHILLY AIR WILL SPREAD INTO THE  
NORTHEAST/MID-ATLANTIC IN MODIFIED FORM, WITH HIGH TEMPERATURES  
10-30F BELOW AVERAGE FOR ONE OF THE COLDEST DAYS OF THE SEASON  
THUS FAR. THEN, TE CENTRAL U.S. WILL SEE A PRONOUNCED WARMING  
TREND NEXT WEEK WITH EXPANDING COVERAGE OF MAX/MIN TEMPERATURES  
10-20F ABOVE NORMAL TUESDAY ONWARD WITH SOME LOCALLY WARMER  
READINGS POSSIBLE ON SOME DAYS. EXPECT MOST OF THE WEST TO SEE  
TEMPERATURES WITHIN 10F ON EITHER SIDE OF NORMAL THROUGH THE  
PERIOD.  
 
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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