975  
FXUS02 KWBC 040654  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
253 AM EDT FRI NOV 04 2022  
 
VALID 12Z MON NOV 07 2022 - 12Z FRI NOV 11 2022  
 
...CHILLY PATTERN OVER THE WEST WITH SIGNIFICANT RAIN/MOUNTAIN  
SNOW OVER SOME AREAS...  
 
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD BEGINS MONDAY WITH AN UPPER LOW OVER THE  
PACIFIC NORTHWEST WHICH SHOULD AMPLIFY FURTHER AND DIVE SOUTHWARD  
THROUGH ABOUT WEDNESDAY BEFORE IT SHIFTS INLAND TOWARDS THE  
NORTHERN ROCKIES/HIGH PLAINS IN RESPONSE TO ANOTHER POSSIBLE  
CLOSED LOW OFF THE NORTHWEST COAST LATE NEXT WEEK. THIS BRINGS A  
PERIOD OF WIDESPREAD MODERATE TO HEAVY RAIN/SNOW TO MUCH OF THE  
WESTERN AND SOUTHWESTERN U.S. AS WELL AS AN OVERALL CHILLY  
TEMPERATURE PATTERN. MEANWHILE, UPPER LEVEL RIDGING SHOULD BUILD  
OVER THE EAST WHILE TO THE SOUTH, AN AREA OF LOW PRESSURE NEAR THE  
BAHAMAS NEXT WEEK LOOKS TO MERGE WITH ENERGY OVER THE EASTERN  
GULF POSSIBLY SPREADING MODEST RAINFALL INTO SOME AREAS NEAR THE  
EAST COAST.  
 
   
..GUIDANCE AND PREDICTABILITY ASSESSMENT
 
 
THE LATEST GUIDANCE SHOWS OVERALL GOOD AGREEMENT THROUGH ABOUT DAY  
5 WITH AN AMPLIFYING TROUGH OVER THE WEST, AMPLIFYING RIDGING OVER  
THE EAST/SOUTH, AND SOME SORT OF SUBTROPICAL FEATURE NEAR  
FLORIDA/THE BAHAMAS. THERE REMAIN SOME LINGERING DIFFERENCES IN  
THE DETAILS OF THE WESTERN TROUGH AND THE SOUTHEAST U.S. LOW, BUT  
A BLEND OF THE DETERMINISTIC SOLUTIONS SEEMED TO PROVIDE A GOOD  
STARTING POINT WHILE MAINTAINING GOOD CONTINUITY WITH THE PREVIOUS  
WPC FORECAST. AFTER DAY 5/WEDNESDAY, THE GFS AND ECMWF BEGIN TO  
SHIFT THE UPPER LOW INLAND OVER THE NORTHERN ROCKIES/HIGH PLAINS  
IN RESPONSE TO ANOTHER AMPLIFIED TROUGH DROPPING INTO THE  
NORTHEAST PACIFIC/SOUTH OF THE ALEUTIANS. THE 12Z/NOV 3 CMC ON THE  
OTHER HAND, WAS MUCH MORE BLOCKED WITH STRONGER RIDGING OFF THE  
PACIFIC NORTHWEST INTO WESTERN CANADA RESULTING IN A SLOWER/DEEPER  
TROUGHING OVER THE WEST WITH LITTLE TO NO MOVEMENT EASTWARD. A  
LOOK AT THE ENSEMBLES ALSO DID SHOW MORE SUPPORT FOR THE GFS/ECMWF  
SOLUTION RATHER THAN THE DEEPER/BLOCKIER 12Z CMC. AS SUCH, THE WPC  
FORECAST TRENDED TOWARDS A BLEND OF THE ENSEMBLE MEANS WITH THE  
DETERMINISTIC GFS AND ECMWF. A NOTE THOUGH THAT THE LATEST 00Z CMC  
RUN (AVAILABLE AFTER FORECAST ISSUANCE TIME) DID TREND EAST AND  
MORE IN LINE WITH THE GFS AND ECMWF.  
 
NEAR FLORIDA, UNCERTAINTY INCREASES GREATLY REGARDING INTERACTION  
OF AN UPPER LOW IN THE EASTERN GULF AND SOME SORT OF LIKELY  
SUBTROPICAL LOW PRESSURE AREA NEAR THE BAHAMAS. THE MODELS SUGGEST  
THESE FEATURES SHOULD PHASE TOGETHER AROUND MID NEXT WEEK, BUT THE  
ECMWF SHOWS THIS FEATURE MORE INFLUENCED BY THE APPROACHING TROUGH  
INTO THE NORTH-CENTRAL U.S. PULLING THE SYSTEM UP THE EAST COAST.  
THE GFS AND CMC HOWEVER, KEEP THE FEATURE SEPERATE AND LINGERING  
OVER THE EASTERN GULF OR FLORIDA. THE WPC FORECAST TOOK A MORE  
CONSERVATIVE APPROACH COMPARED TO THE ECMWF (WHICH WOULD BRING  
HEAVY RAINFALL MUCH FARTHER NORTH INTO THE MID-ATLANTIC REGION)  
WITH A BLEND MORE TOWARDS THE ENSEMBLE MEANS AND THE GFS.  
 
   
..WEATHER/HAZARD HIGHLIGHTS
 
 
THE WEST WILL SEE A BROAD AREA OF RAIN AND HIGHER ELEVATION SNOW  
DURING THE PERIOD AS THE UPPER TROUGH AMPLIFIES DOWN THE COAST AND  
EVENTUALLY MOVES INLAND. BEGINNING MONDAY (AS THIS EVENT SHOULD  
BEGIN THIS WEEKEND DURING THE NOW SHORT RANGE PERIOD), THE HIGHEST  
PRECIPITATION TOTALS SHOULD EXTEND FROM THE COASTAL RANGES AND  
SIERRA NEVADA IN CALIFORNIA THROUGH THE GREAT BASIN AND  
NORTH-CENTRAL/CENTRAL ROCKIES. AREAS ACROSS THE PACIFIC NORTHWEST  
SHOULD DRY OUT BY EARLY TO MIDWEEK. MOISTURE/ENERGY EJECTING FROM  
THE WESTERN TROUGH MAY SPREAD ONE OR MORE AREAS OF PRECIPITATION  
ACROSS THE NORTHERN TIER DURING THE FIRST HALF OF NEXT WEEK, WITH  
MORE WIDESPREAD RAIN (OR SNOW DEPENDING ON SYSTEM STRENGTH) ACROSS  
PARTS OF THE NORTHERN PLAINS/UPPER MIDWEST LATE WEEK AS THE MAIN  
TROUGH/LOW MOVES INLAND. A WEAKENING AND STALLING/RETREATING FRONT  
MAY PRODUCE SOME LIGHT RAINFALL OVER PARTS OF THE EAST INTO THE  
SOUTHERN PLAINS EARLY IN THE PERIOD AS MOISTURE ASSOCIATED WITH  
THE BAHAMAS SYSTEM TRACKING TOWARD FLORIDA/SOUTHEASTERN COAST MAY  
SPREAD INTO PARTS OF THE EAST TUESDAY ONWARD. DETAILS OF COVERAGE  
AND TOTALS ARE STILL FAIRLY UNCERTAIN AT THIS TIME, BUT SOME AREAS  
OF LOCALLY MODERATE TO HEAVY RAINFALL MAY BE POSSIBLE.  
 
MUCH BELOW NORMAL TEMPERATURES ARE EXPECTED TO EXPAND ACROSS THE  
WEST THROUGH MUCH OF NEXT WEEK ASSOCIATED WITH THE DEEPENING UPPER  
TROUGH. THE COLDEST AIR WILL LIKELY EXTEND FROM WESTERN CANADA  
INTO MONTANA WITH RECENT FORECASTS CONSISTENTLY SHOWING HIGHS IN  
THAT UP TO 20-40F BELOW NORMAL MONDAY-THURSDAY, EQUATING TO  
DAYTIME HIGHS IN SOME PLACES IN THE TEENS AND SINGLE DIGITS (AND  
BELOW ZERO OVERNIGHT LOWS). SOME LOCATIONS OVER THE WEST MAY SEE  
DAILY RECORDS FOR COLD HIGHS MONDAY-WEDNESDAY. IN CONTRAST, WELL  
ABOVE NORMAL TEMPERATURES WILL PREVAIL OVER MUCH OF THE EAST AND  
AT TIMES OVER THE PLAINS. THE EAST WILL SEE TEMPERATURES 10-25F  
ABOVE NORMAL ESPECIALLY ON MONDAY WHEN WIDESPREAD DAILY RECORDS  
FOR HIGHS AND/OR WARM LOWS ARE POSSIBLE. HIGHS WILL MODERATE NEAR  
THE EAST COAST THEREAFTER WITH INCREASING CLOUDS/MOISTURE BUT LOWS  
WILL REMAIN UNSEASONABLY WARM. TUESDAY-WEDNESDAY SHOULD BE THE  
WARMEST DAYS FOR THE CENTRAL-SOUTHERN PLAINS WITH READINGS 10-20F  
OR SO ABOVE NORMAL.  
 
SANTORELLI  
 
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, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, 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/#PAGE=ERO  
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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