718  
FXUS10 KWNH 031646  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1144 AM EST SAT MAR 03 2018  
 
VALID MAR 03/1200 UTC THRU MAR 07/0000 UTC  
 
12Z MODEL EVALUATION...ALONG WITH MODEL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..POWERFUL NOR'EASTER PULLING AWAY FROM THE EAST COAST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS ARE IN VERY GOOD AGREEMENT IN TAKING THE STRONG  
NOR'EASTER AWAY FROM THE EAST COAST OVER THE NEXT 24 HOURS AND OUT  
OVER THE OPEN ATLANTIC OCEAN. A GENERAL MODEL BLEND WILL BE  
PREFERRED GIVEN THE MINIMAL MASS FIELD SPREAD.  
 
   
..DEEP CLOSED LOW IMPACTING THE WESTERN U.S. TODAY
 
   
..NEGATIVELY TILTED TROUGH APPROACHING THE PLAINS ON SUNDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS  
06Z GEFS MEAN/00Z ECENS MEAN BLEND...AFTER 60 HOURS  
CONFIDENCE: ABOVE AVERAGE...BECOMING BELOW AVERAGE AFTER 60 HOURS  
 
A DEEP LAYER CLOSED LOW AND ASSOCIATED BROAD TROUGH IMPACTING THE  
WEST COAST WILL GRADUALLY BE CROSSING THE INTERMOUNTAIN REGION  
THROUGH SUNDAY. THE MODELS THEN INDICATE ENERGY LIFTING OUT OF THE  
BASE OF THE TROUGH BY SUNDAY NIGHT WHICH WILL ALLOW THE TROUGH TO  
TAKE ON A NEGATIVE TILT OUT ACROSS THE CENTRAL/NORTHERN PLAINS ON  
MONDAY. EXPECT A NEW MID/UPPER LEVEL LOW CENTER TO EVOLVE AS WELL  
AS THE SYSTEM AMPLIFIES. SURFACE LOW PRESSURE OVER THE GREAT BASIN  
THROUGH SUNDAY IS EXPECTED TO REORGANIZE OVER THE PLAINS ON MONDAY  
AND BEGIN LIFTING ACROSS THE UPPER MIDWEST BY MONDAY NIGHT. THE  
GUIDANCE IS GENERALLY IN GOOD AGREEMENT WITH THEIR TIMING AND  
DEPTH OF THE TROUGH EVOLUTION THROUGH MONDAY, AND THE SPREAD WITH  
THE SURFACE LOW DETAILS ACROSS THE PLAINS IS RATHER MINIMAL.  
 
MORE SPREAD THOUGH OCCURS MONDAY AND TUESDAY AS THIS SYSTEM  
ENCOUNTERS A VERY BLOCKY DOWNSTREAM PATTERN OVER EASTERN NORTH  
AMERICA. MOST OF THE MODELS REFOCUS THEIR RESPECTIVE CLOSED LOW  
FEATURES MORE TO THE EAST OVER PARTS OF THE MIDDLE MISSISSIPPI  
VALLEY AND THE LOWER GREAT LAKES REGION BY THE END OF THE PERIOD  
AND ALSO SHOW SOME BINARY INTERACTION WITH A CLOSED LOW FARTHER  
NORTH OVER ONTARIO TO THE SOUTH OF HUDSON BAY. THE 00Z UKMET TENDS  
TO HAVE MORE ENERGY FARTHER NORTH OVER THE GREAT LAKES REGION AND  
TAKES ITS SURFACE LOW A LITTLE NORTH OF THE MODEL CONSENSUS. THE  
12Z GFS IS A LITTLE MORE SUPPRESSED WITH ITS HEIGHT FALLS AND HAS  
MORE ENERGY IMPACTING THE OHIO VALLEY. THE 00Z ECMWF IS NORTH OF  
THE GFS WITH ITS SURFACE LOW EVOLUTION ON TUESDAY AND MANY OF THE  
ECENS MEMBERS ARE NORTH AS WELL IN SUPPORT OF THE ECMWF. THE GEFS  
MEMBERS TEND TO HAVE TWO CAMPS OF LOW PRESSURE BY LATE TUESDAY  
WITH ONE AREA OF LOW PRESSURE OVER OHIO AND ANOTHER ONE BACK OVER  
ILLINOIS. HOWEVER, ALOFT, THE GEFS MEAN IS A BIT NORTHWEST OF THE  
DETERMINISTIC GFS. THE 00Z CMC AND MANY CANADIAN ENSEMBLE MEMBERS  
ATTEMPT TO SPLIT THE DIFFERENCE LATITUDINALLY WITH THE LOW  
PRESSURE WAVE. CONFIDENCE BECOMES LIMITED BY TUESDAY, BUT THE  
PREFERENCE WILL BE FOR A GENERAL MODEL BLEND THROUGH MONDAY WITH  
THIS SYSTEM, AND THEN A COMPROMISE BETWEEN THE 06Z GEFS MEAN AND  
00Z ECENS MEAN THEREAFTER. THIS WOULD BEST APPROXIMATE THE MODEL  
CONSENSUS AS WELL.  
 
   
..TROUGH DIGGING SOUTHEAST ACROSS THE NORTHEAST ON MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF  
CONFIDENCE: AVERAGE  
 
THE MODELS TAKE A PORTION OF THE TROUGH/CLOSED LOW JUST SOUTHWEST  
OF HUDSON BAY AND SLOWLY SHIFT IT SOUTHEAST ACROSS QUEBEC ON  
SUNDAY AND THEN IN MORE OF SHEARED FASHION DOWN ACROSS THE  
NORTHEAST ON MONDAY AS THE SYSTEM ENCOUNTERS A BLOCKING HIGH THAT  
IS SETTLING SOUTHWEST FROM SOUTHERN GREENLAND. THE GUIDANCE  
COMPARED TO YESTERDAY HAS TRENDED TOWARD MORE ENERGY DROPPING  
SOUTHEAST ACROSS THE NORTHEAST WITH A BETTER DEFINED CLOSED LOW  
FEATURE. THIS ENERGY THEN QUICKLY GOES SOUTHEAST AND OFFSHORE BY  
MONDAY. THE 12Z NAM AND 00Z CMC BECOME A LITTLE SLOWER THAN THE  
12Z GFS AND 00Z ECMWF, BUT THE 00Z UKMET DOES FAVOR THE SLOWER  
CAMP. THE LATEST GEFS MEAN AND ECENS MEAN FAVOR THE FASTER  
SOLUTIONS. WILL LEAN TOWARD THE MORE PROGRESSIVE GFS AND ECMWF  
SOLUTIONS FOR NOW.  
 
   
..SHORTWAVE TROUGH OVER THE NORTHERN HIGH PLAINS TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE GUIDANCE DROPS ANOTHER SHORTWAVE TROUGH DOWN ACROSS THE  
NORTHERN HIGH PLAINS BY TUESDAY. THERE IS SOME MINOR DEPTH  
DIFFERENCES BY LATE TUESDAY OVER MONTANA WITH THE HEIGHT FALLS,  
BUT WILL SUGGEST A GENERAL MODEL BLEND FOR THE TIME BEING.  
 
PREVIOUS MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
PREVIOUS 500 MB FORECASTS AT  
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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