614  
FXUS02 KWBC 091901  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 PM EST SUN JAN 09 2022  
 
VALID 12Z WED JAN 12 2022 - 12Z SUN JAN 16 2022  
   
..OVERVIEW
 
 
GENERAL RIDGING OVER THE WESTERN U.S. IS EXPECTED TO CONTINUE INTO  
THE MEDIUM-RANGE PERIOD AS SHORTWAVES DIVE ACROSS THE CENTRAL  
CANADA INTO THE NORTHERN TIER WHILE A LINGERING LOW/TROUGH OFF  
BAJA CALIFORNIA IS FORECAST TO EVENTUALLY TRACK INTO THE SOUTHERN  
PLAINS. THIS SPLIT FLOW PATTERN COULD POTENTIALLY PHASE NEAR THE  
EAST COAST WHERE CYCLOGENESIS WOULD BE POSSIBLE BY NEXT WEEKEND.  
MODEL ENSEMBLE MEANS FAVOR THIS PHASING SCENARIO IN CONTRAST WITH  
THE DETERMINISTIC SOLUTIONS WHICH CONTINUE TO INDICATE A SPLIT  
DECISION IN THIS REGARD.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
OVERALL, THE ENSEMBLE MEANS HAVE MAINTAINED RELATIVELY GOOD  
RUN-TO-RUN CONSISTENCY IN PREDICTING THE PATTERN EVOLUTION ACROSS  
THE U.S. THROUGH THE MEDIUM-RANGE PERIOD. THE LARGEST DISCREPANCY  
WAS NOTED WITH REGARD TO HOW THE UPPER LOW/TROUGH OFF BAJA  
CALIFORNIA IS HANDLED. THE ECMWF SWITCHED TO A MUCH SLOWER  
SOLUTION IN THE 00Z RUN IN THE SHORT-RANGE, THUS KEEPING THIS  
FEATURE WELL OFF THE COAST INTO THE MEDIUM-RANGE. THE GFS TRENDED  
TOWARD THIS SLOW SOLUTION AS WELL STARTING WITH THE 06Z RUN. THIS  
SUDDEN SLOW DOWN OF THE UPPER LOW HAS RESULTED IN A MARKED  
LOWERING OF RAIN CHANCES OVER THE SOUTHERN PLAINS MIDWEEK. THE  
ENSEMBLE MEANS INDICATE THAT THIS UPPER LOW/TROUGH WILL EVENTUALLY  
LIFT TOWARD THE SOUTHWEST LATE NEXT WEEK AS THE NEXT SHORTWAVE  
DIVES ACROSS THE CANADIAN PRAIRIES TOWARD THE NORTHERN PLAINS.  
MODELS THEN BEGIN TO DIVERGE AS TO WHETHER THESE TWO FEATURES WILL  
EVENTUALLY PHASE OR REMAIN SPLIT AS THEY REACH THE VICINITY OF THE  
EAST COAST BY NEXT WEEKEND. IT APPEARS THAT THE ENSEMBLE MEANS  
SUPPORT THE PHASING SCENARIO IN CONTRAST WITH THE DETERMINISTIC  
SOLUTIONS WHICH CONTINUE TO INDICATE A SPLIT DECISION IN THIS  
REGARD. THE ECMWF AND CMC HAVE BEEN IN FAVOR OF PHASING AND  
CYCLOGENESIS NEAR THE EAST COAST WHEREAS THE GFS SUPPORTS A MORE  
SEPARATION BETWEEN THE TWO STREAMS WITH ITS TYPICALLY FASTER  
SOLUTION.  
 
PRIOR TO THE WEEKEND, MODELS AND ENSEMBLES ARE IN GOOD AGREEMENT  
FOR A DEEP TROUGH TO EXIT THE EAST COAST THU-FRI WITH A STRONG  
SIGNAL FOR CYCLOGENESIS OFF THE EAST COAST. IT APPEARS THAT THE  
HEAVY RAIN WOULD STAY OFF SHORE WITH WHAT APPEARS TO BE A DEEP  
CYCLONE IN THE MAKING.  
 
A MULTI-MODEL/ENSEMBLE BLEND WAS USED TO COMPOSE THIS MORNING'S  
WPC MEDIUM-RANGE FORECASTS.  
   
..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.  
 
KONG/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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