601  
FXUS10 KWNH 021845  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
244 PM EDT FRI AUG 02 2019  
 
VALID AUG 02/1200 UTC THRU AUG 06/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION AND PREFERENCES/CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..CENTRAL/SOUTHERN PLAINS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS SHOW MID-LEVEL SHORTWAVE ENERGY DROPPING DOWN ACROSS  
EASTERN KS TONIGHT AND EARLY SATURDAY BEFORE THEN ADVANCING SOUTH  
DOWN ACROSS THE SOUTHERN PLAINS TOWARD THE RED RIVER VALLEY OF THE  
SOUTH. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THEIR  
TIMING AND STRENGTH, AND SO A GENERAL MODEL BLEND WILL BE FAVORED  
WITH THIS ENERGY.  
 
   
..OH VALLEY/MID-ATLANTIC/NORTHEAST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
AN UPPER TROUGH WILL BE SWINGING ACROSS THE NORTHEAST U.S. THIS  
WEEKEND AS A DEEPENING CLOSED LOW IMPACTS PORTIONS OF SOUTHEAST  
CANADA. MEANWHILE, THE GUIDANCE SUPPORTS A SHORTWAVE IMPULSE  
DROPPING SOUTHEAST FROM THE GREAT LAKES REGION AND CROSSING THE  
UPPER OH VALLEY AND THE MID-ATLANTIC REGION GOING THROUGH MONDAY.  
THE 12Z UKMET MAY BE TAD TOO WEAK WITH THIS SHORTWAVE, BUT THE  
GUIDANCE IS OTHERWISE IN GOOD AGREEMENT WITH THE TIMING AND DEPTH  
OF TH ENERGY. A GENERAL MODEL BLEND WILL BE PREFERRED.  
 
   
..PACIFIC NORTHWEST/SOUTHWEST CANADA
 
   
..UPPER MIDWEST BY MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS  
NON-NAM BLEND...AFTER 60 HOURS  
CONFIDENCE: ABOVE AVERAGE  
 
THE GUIDANCE AGREES IN TAKING A POSITIVELY TILTED LONGWAVE TROUGH  
ACROSS SOUTHWEST BRITISH COLUMBIA, VANCOUVER ISLAND, AND OFF THE  
NORTHWEST COAST AND MOVING THE WAVE NORTHEAST INTO CENTRAL CANADA  
OVER THE WEEKEND. THE ENERGY WILL THEN BEGIN TO DIG A BIT TO THE  
SOUTHEAST AND CROSS INTO THE UPPER MIDWEST ON MONDAY. THE GUIDANCE  
IS IN GOOD AGREEMENT WITH THE OVERALL EVOLUTION OF THIS ENERGY  
THROUGH THE PERIOD WITH EXCEPTION TO THE 12Z NAM WHICH BEGINS TO  
OUTRUN THE GLOBAL MODELS WITH THE TIMING OF ITS CLOSED LOW PASSING  
JUST SOUTHWEST OF HUDSON BAY BY THE END OF THE PERIOD. A GENERAL  
MODEL BLEND THROUGH 60 HOURS SHOULD SUFFICE, FOLLOWED BY A NON-NAM  
BLEND THEREAFTER.  
 
   
..UPPER LOW/TROUGH OFF THE PACIFIC NORTHWEST ON SUNDAY/MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS TAKE A PORTION OF THE ENERGY TRAVERSING SOUTHWEST  
CANADA AND PINCH OFF A NEW TROUGH/CLOSED LOW JUST OFFSHORE OF  
WA/OR BY SUNDAY. THE MODELS ARE IN REASONABLY GOOD AGREEMENT WITH  
THEIR POSITIONING AND DEPTH OF THE SYSTEM, AND THUS A GENERAL  
MODEL BLEND WILL BE PREFERRED.  
 
   
..UPPER TROUGH OVER THE GULF COAST/SOUTHEAST
 
   
..SURFACE LOW DEVELOPMENT NEAR THE SOUTHEAST COAST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
 
A BROAD UPPER TROUGH OVER THE GULF COAST STATES AND ADJACENT AREAS  
OF THE TN VALLEY AND THE SOUTHEAST WILL GENERALLY REMAIN IN PLACE  
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. THERE IS MINIMAL  
SPREAD WITH THE LARGER SCALE DETAILS OF THE TROUGH, AND SO A  
GENERAL MODEL BLEND WILL BE PREFERRED WITH THIS ENERGY.  
 
REGARDING THE SURFACE TROUGH LIFTING UP OFF THE SOUTHEAST  
COASTLINE, THE MODELS STILL FAVOR SOME WEAK SURFACE LOW  
DEVELOPMENT ALONG IT AS THE ENERGY BEGINS TO TURN NORTHEAST AND  
OUT TO SEA TO THE EAST OF THE NC OUTER BANKS ON SUNDAY. THE 12Z  
NAM IS THE STRONGEST SOLUTION WITH THE 12Z CMC SOLUTION NOW THE  
WEAKEST. A GENERAL MODEL BLEND OF THE GUIDANCE SHOULD RESOLVE THE  
DIFFERENCES SEEN IN THE STRENGTH OF THE LOW FOR THIS PERIOD.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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