011  
FXUS02 KWBC 072035  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
334 PM 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 AS A TROUGH EXTENDS SOUTHWARD FROM A DEEP UPPER  
LOW OVER EAST-CENTRAL CANADA AND RIDGING PREVAILS 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 NEAR THE CALIFORNIA COAST THROUGH THE EARLY PART  
OF THE WORKWEEK. ANOTHER PACIFIC SHORTWAVE SHOULD APPROACH THE  
WEST COAST AROUND MIDWEEK WITH GUIDANCE SHOWING VARYING IDEAS FOR  
WHAT FORM IT WILL TAKE THEREAFTER AND HOW IT MAY INTERACT WITH THE  
LEADING UPPER LOW. MEANWHILE IN THE EAST, THE PATTERN MAY  
DEAMPLIFY SOMEWHAT BY MID-LATE WEEK BUT ONE OR MORE SHORTWAVES OF  
UNCERTAIN STRENGTH AND TIMING WILL LIKELY TRACK THROUGH THE  
LINGERING BROAD MEAN TROUGH.  
   
..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. HOWEVER THE  
FULL ARRAY OF GUIDANCE HAS NOT IMPROVED CONFIDENCE WITH ONGOING  
UNCERTAINTIES IN THE REST OF THE FORECAST, BUT THERE ARE SOME  
COMMON THEMES THAT PROVIDE DECENT CONTINUITY IN PRINCIPLE.  
 
THERE IS STILL A MAJORITY CLUSTER THAT HAS A COMPACT CLOSED LOW  
TRACKING ALONG THE CENTRAL-SOUTHERN CALIFORNIA COAST INTO FAR  
NORTHERN BAJA CALIFORNIA MONDAY-WEDNESDAY WITH SUBSEQUENT EJECTION  
IN RESPONSE TO UPSTREAM FLOW. THE NEW 12Z CMC HAS DEVIATED FROM  
CONSENSUS BY PULLING ITS CLOSED LOW FROM A MORE SOUTHERN PART OF  
THE OVERALL SHORTWAVE. THEN MODELS/ENSEMBLES CONTINUE TO SHOW  
THEIR DIVERGENCE FOR DETAILS OF THE NEXT PACIFIC SHORTWAVE.  
MULTIPLE GFS RUNS HAVE BEEN CLOSING A LOW OVER THE EASTERN  
PACIFIC, AND NOW THE 12Z CMC DOES THE SAME FARTHER SOUTH, WHILE  
THE 00Z ECMWF/CMC AGREED MORE WITH THE ENSEMBLE MEANS WHICH HAVE  
BEEN MAINTAINING AN OPEN SHORTWAVE AT LEAST UNTIL THE FEATURE  
CROSSES THE WEST COAST. INTERESTINGLY BY LATE NEXT WEEK THE  
06Z/12Z GFS RUNS ARE NOT FAR FROM THE MAJORITY SOLUTION FOR THE  
LARGE SCALE PATTERN AFTER SUBTRACTING THEIR EASTERN PACIFIC UPPER  
LOW. THE 12Z ECMWF PROVIDES YET ANOTHER OPTION, TRENDING SOMEWHAT  
SLOWER/MORE SEPARATED AND BRINGING THE BEST CONCENTRATION OF  
ENERGY INTO THE NORTHWEST INSTEAD OF DIGGING INTO THE GREAT  
BASIN/FOUR CORNERS. PREFERENCE BASED ON 00Z/06Z GUIDANCE WAS TO  
FOLLOW THE MODEL CONSENSUS FOR THE LEADING PACIFIC FEATURE AND  
THEN WEIGHT THE FORECAST MORE TO THE 00Z ECMWF/CMC AND 06Z  
GEFS/00Z ECMWF MEANS WHEN THE NEXT SHORTWAVE COMES INTO THE  
PICTURE.  
 
MEANWHILE IN THE BROAD CYCLONIC FLOW FARTHER EAST, THE BEST SIGNAL  
EXISTS FOR A SHORTWAVE TO CROSS THE EASTERN HALF OF THE COUNTRY  
AROUND WEDNESDAY-THURSDAY. AS CAN BE THE MODEL'S OCCASIONAL BIAS  
WITH UPPER TROUGHS, THE LATEST CMC RUNS ARE QUITE AMPLIFIED (EVEN  
PULLING OFF A CLOSED LOW EAST OF FLORIDA BY FRIDAY IN THE NEW 12Z  
RUN). EVEN IF NOT QUITE AN OUTLIER, THESE CMC RUNS ARE EXTREME  
COMPARED TO MOST OF THE FULL ENSEMBLE ENVELOPE.  
 
THE LATE-PERIOD TRANSITION TO HALF MEANS/HALF MODELS (VERSUS ALL  
MODELS EARLY) KEPT SOMEWHAT MORE 00Z ECMWF INPUT RELATIVE TO THE  
06Z GFS/00Z CMC GIVEN THE DESIRE TO DOWNPLAY GFS SPECIFICS NEAR  
THE WEST COAST AND THE CMC IN THE EAST.  
   
..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. LOCALLY MODERATE TO HEAVY ACTIVITY  
MAY BE POSSIBLE OVER THE OLYMPICS AND VICINITY AROUND MIDWEEK WHEN  
THE AREA MAY BE ON THE SOUTHEAST FRINGE OF AN ATMOSPHERIC RIVER  
EVENT AIMED AT VANCOUVER ISLAND. THE UPPER LOW INITIALLY DROPPING  
SOUTHWARD NEAR THE CALIFORNIA COAST MAY SPREAD MOISTURE INTO THE  
SOUTHWEST BY TUESDAY-WEDNESDAY. THIS PRECIPITATION SHOULD BE  
FAIRLY LIGHT BUT HEAVIER RAINFALL MAY DEVELOP OVER THE SOUTHERN  
PLAINS AND LOWER MISSISSIPPI VALLEY BY MID-LATE WEEK AS THE UPPER  
LOW TRACKS/SHEARS NORTHEASTWARD AND THE SURFACE PATTERN BECOMES  
MORE FAVORABLE FOR DRAWING MOISTURE NORTHWARD FROM THE GULF OF  
MEXICO. IT WILL TAKE ADDITIONAL TIME TO REFINE THE DETAILS OF  
RAINFALL COVERAGE AND MAGNITUDE THOUGH.  
 
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 THE CENTRAL U.S. WILL SEE A PRONOUNCED WARMING  
TREND NEXT WEEK WITH EXPANDING COVERAGE OF MAX/MIN TEMPERATURES  
10-20F ABOVE NORMAL TUESDAY ONWARD. SOME LOCATIONS IN THE  
NORTHERN TWO-THIRDS OF THE PLAINS MAY SEE EVEN WARMER READINGS  
MID-LATE WEEK. ACROSS THE WEST EXPECT TO SEE DAYTIME HIGHS WITHIN  
10F ON EITHER SIDE OF NORMAL THROUGH THE PERIOD, WHILE ABOVE  
NORMAL LOWS SHOULD BECOME MORE PREVALENT WITH TIME. BEST  
POTENTIAL FOR ONE OR MORE DAYS WITH PLUS 10F OR GREATER ANOMALIES  
FOR LOWS WOULD BE OVER THE SOUTHWEST AND PACIFIC NORTHWEST AS  
SEPARATE FEATURES BRING CLOUDS/MOISTURE INTO THOSE REGIONS.  
 
RAUSCH/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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE  
NORTHERN GREAT BASIN, TUE-THU, JAN  
11-JAN 13.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS,  
AND THE TENNESSEE VALLEY, THU-FRI, JAN 13-JAN 14.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE MIDDLE  
MISSISSIPPI VALLEY, THE GREAT LAKES,  
THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS, MON-TUE,  
JAN 10-JAN 11.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE  
MID-ATLANTIC, THE NORTHEAST, AND THE GREAT  
LAKES, TUE-WED, JAN 11-JAN 12.  
 
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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