331  
FXUS10 KWNH 021856  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
156 PM EST FRI MAR 02 2018  
 
VALID MAR 02/1200 UTC THRU MAR 06/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION...ALONG WITH MODEL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..POWERFUL NOR'EASTER IMPACTING THE MID-ATLANTIC/NORTHEAST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS ARE IN VERY GOOD AGREEMENT IN TAKING THE STRONG  
NOR'EASTER CURRENTLY IMPACTING THE MID-ATLANTIC AND NORTHEAST OFF  
TO THE EAST AND OUT TO SEE OVER THE NEXT 24 TO 36 HOURS. A GENERAL  
MODEL BLEND WILL BE PREFERRED AT THIS TIME GIVEN GOOD MODEL MASS  
FIELD CLUSTERING.  
 
   
..DEEP CLOSED LOW IMPACTING THE WESTERN U.S. THROUGH SATURDAY
 
   
..NEGATIVELY TILTED TROUGH APPROACHING THE PLAINS ON SUNDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS  
12Z GFS/12Z UKMET/12Z ECMWF BLEND...AFTER 60 HOURS  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE MODELS ALL TAKE A STRONG CLOSED LOW OFFSHORE THE PACIFIC  
NORTHWEST TODAY GRADUALLY SOUTH WHICH BROADENS OUT OVER THE NEXT  
DAY AND THEN MOVES INLAND ACROSS THE INTERMOUNTAIN REGION. THIS  
WILL ALLOW A BROAD TROUGH TO ENVELOPE ALL OF THE WEST THROUGH  
SUNDAY. THE GUIDANCE THOUGH INDICATES THAT ENERGY LIFTING OUT OF  
THE BASE OF THE TROUGH BY LATE SUNDAY WILL ALLOW THE TROUGH TO  
TAKE ON A NEGATIVE TILT OUT ACROSS THE CENTRAL/NORTHERN PLAINS  
THROUGH MONDAY BEFORE THEN CLOSING OFF IN THE MID LEVELS. SURFACE  
LOW PRESSURE OVER THE GREAT BASIN THROUGH SUNDAY IS EXPECTED TO  
REORGANIZE OVER THE PLAINS ON MONDAY AND BEGIN LIFTING TOWARD THE  
UPPER MIDWEST. THE GUIDANCE IS GENERALLY IN GOOD AGREEMENT WITH  
THEIR TIMING AND DEPTH OF THE TROUGH EVOLUTION THROUGH EARLY  
MONDAY, BUT BY THE END OF THE PERIOD THERE ARE SOME LATITUDINAL  
DIFFERENCES WITH THE CLOSED LOW EVOLUTION AND THE INTENSITY OF  
SURFACE LOW PRESSURE. THE 12Z ECMWF IS STILL ON THE NORTH SIDE OF  
THE GUIDANCE BY THE END OF THE PERIOD, WITH THE 12Z UKMET A LITTLE  
FARTHER SOUTH. THE 12Z NAM AND 12Z GFS ARE WELL CLUSTERED WITH  
THEIR TIMING/PLACEMENT OF THE HEIGHT FALLS, BUT THE GFS IS  
STRONGER AT THE SURFACE. THE 12Z CMC IS A TAD ON THE FASTER SIDE  
OF THE MODEL SPREAD. GIVEN THE GRADUAL CONSOLIDATION NOTED AMONG  
THE GFS, ECMWF AND UKMET SOLUTIONS, A BLEND OF THESE MODELS WILL  
BE PREFERRED AFTER 60 HOURS, WITH A GENERAL MODEL BLEND PRIOR TO  
THIS.  
 
   
..TROUGH DIGGING SOUTHEAST ACROSS THE NORTHEAST ON MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS AND 12Z 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. NOT EVERY MODEL  
SHEARS ALL OF THE ENERGY DOWN ACROSS THE NORTHEAST THOUGH AS THE  
12Z NAM, 12Z GFS, 12Z ECMWF AND THE 12Z CMC KEEP A SIZABLE DEGREE  
OF ENERGY UP ACROSS SOUTHEAST CANADA TO THE WEST OF THE BLOCKING  
RIDGE. THE 12Z UKMET WAS MORE EMPHATIC ON BRINGING MORE ENERGY  
FARTHER SOUTHEAST ACROSS THE NORTHEAST. REGARDING THE BEST MODEL  
CLUSTERING, THE GFS AND ECMWF ARE THE CLOSEST AND HAVE SUPPORT  
FROM THE LATEST GEFS MEAN. WILL FAVOR A BLEND OF THE GFS AND ECMWF  
AT THIS TIME AS A RESULT.  
 
 
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