253  
FXUS02 KWBC 010617  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
116 AM EST FRI FEB 01 2019  
 
VALID 12Z MON FEB 04 2019 - 12Z FRI FEB 08 2019  
 
...MUCH ABOVE AVERAGE TEMPERATURES FOR THE EASTERN HALF OF THE  
LOWER 48 EARLY NEXT WEEK...  
 
   
..OVERVIEW
 
 
ACTIVE PATTERN IN THE WEST WILL TRANSLATE EASTWARD NEXT WEEK AS A  
DEEP TROUGH DIGS THROUGH THE GREAT BASIN MON/TUE AND THEN LIFTS  
NORTHEASTWARD TOWARD THE GREAT LAKES. A SECONDARY CANADIAN  
SHORTWAVE WILL BRING IN A RENEWED PUSH OF COLD AIR FOR THE  
NORTHERN ROCKIES INTO THE HIGH PLAINS. THE EAST WILL SEE A  
DRAMATIC RISE IN TEMPERATURES TO WELL ABOVE FREEZING (RATHER THAN  
WELL BELOW ZERO) AHEAD OF THE PACIFIC SYSTEM. RECORD HIGH  
TEMPERATURES MON-WED ARE EVEN POSSIBLE WHERE RECORD LOW  
TEMPERATURES WERE JUST OBSERVED YESTERDAY/THIS MORNING.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE 18Z GFS AND 12Z ECMWF CLUSTERED FAIRLY WELL WITH THEIR  
ENSEMBLE MEANS TO START THE FORECAST MON-TUE AS AN UPPER LOW DROPS  
SOUTHWARD NEAR THE WA/OR COAST AND THEN INTO NORTHERN CALIFORNIA.  
ARCTIC BOUNDARY TO THE NORTH WILL PUSH OVER THE DIVIDE WITH COLDER  
AIR SINKING SOUTHWARD AND BOTH WESTWARD/EASTWARD THROUGH SOME  
MOUNTAIN PASSES. TO THE EAST, ANOTHER SURFACE LOW WILL LIFT FROM  
THE MIDWEST INTO SOUTHERN CANADA AND DRAG ITS COLD FRONT TO THE  
MID-ATLANTIC/OHIO VALLEY BY WEDNESDAY. AT THAT TIME, THE PACIFIC  
SYSTEM WILL SLIDE INTO THE PLAINS AND BEGIN TO TURN NORTHEASTWARD  
TOWARD THE GREAT LAKES BY EARLY THURSDAY. THE GFS/GEFS HAVE BEEN  
LESS CONSISTENT IN TIMING/TRACK OF THE MID-WEEK TO LATE WEEK  
PERIOD WHILE THE ECMWF AND ITS ENSEMBLE MEAN HAVE TRENDED A BIT  
SLOWER OVER THE PAST SEVERAL CYCLES WITH THE WESTERN TROUGH. OPTED  
TO RELY MOSTLY ON THAT SLOWER GUIDANCE WITH ONLY A SMALL WEIGHTING  
TO THE SLIGHTLY QUICKER 12Z NAEFS. UPSTREAM PACIFIC FLOW BECOMES  
QUITE UNCERTAIN AS THE RIDGE CENTER MOVES NORTHWARD INTO ALASKA  
NEXT THURSDAY. BACK TO THE EAST, ENSEMBLES SEEM TO TAKE THE  
SURFACE LOW EASTWARD OUT THE ST. LAWRENCE VALLEY WHICH WILL BRING  
AN END TO THE WELL ABOVE AVERAGE TEMPERATURES.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
DEEP SYSTEM IN THE WEST WILL BRING VALLEY RAIN AND HIGHER  
ELEVATION SNOW (WITH LOWERING SNOW LEVELS), WIND, AND COOLER  
TEMPERATURES FROM OREGON/SOUTHERN IDAHO SOUTHWARD AND  
SOUTHEASTWARD. TO ITS NORTH WILL BE A SLOWLY ADVANCING ARCTIC  
FRONT THAT WILL BRING WELL BELOW AVERAGE TEMPERATURES TO MUCH OF  
MONTANA WHERE HIGHS WILL STRUGGLE TO GET TO ZERO (ABOUT 20-45  
DEGREES BELOW AVERAGE) THAT WILL BLEED INTO THE DAKOTAS AS WELL.  
THE SIERRAS WILL SEE ANOTHER ROUND OF SNOW WITH MORE THAN A FOOT  
LIKELY. TO THE EAST, GREAT LAKES SYSTEM WILL SPREAD SNOW FROM THE  
UPPER MIDWEST TO THE NORTHERN LAKES WITH PLAIN RAIN FOR MUCH OF  
THE EAST SOUTH OF ABOUT ~45N (NY-VT/CANADA BORDER). RECORD MILD  
TEMPERATURES MAY PRECEDE THE FRONT FROM THE MIDWEST TO THE  
NORTHEAST WITH ANOMALIES OF ABOUT +10 TO +30 (GENERALLY ABOVE  
FREEZING TO THE NORTH AND 50S/60S IN THE MID-ATLANTIC.  
 
BY NEXT THURSDAY, PACIFIC SYSTEM WILL LIFT INTO THE GREAT LAKES  
WITH ANOTHER SNOW THREAT FOR THE UPPER MIDWEST EASTWARD TO  
NORTHERN NEW ENGLAND. WARM SECTOR RAIN FROM THE MID-MISSISSIPPI  
VALLEY EASTWARD MAY BE MUCH MORE WIDESPREAD AND LOCALLY HEAVY WITH  
INCREASED GULF MOISTURE. THE WEST WILL TREND QUIETER BUT  
TEMPERATURES WILL BE NEAR TO BELOW AVERAGE.  
 
FRACASSO  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION AND WINTER WEATHER OUTLOOK  
PROBABILITIES ARE FOUND 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  
 

 
 
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