763  
FXUS10 KWNH 251711  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1211 PM EST SAT JAN 25 2020  
 
VALID JAN 25/1200 UTC THRU JAN 29/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..DEEP CLOSED LOW MOVING ACROSS THE NORTHEAST THROUGH SUNDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
VERY GOOD AGREEMENT PERSISTS IN THE EVOLUTION OF A STRONG CLOSED  
LOW CURRENTLY ACROSS THE OHIO VALLEY LIFTING NORTHEAST SLOWLY  
THROUGH THE WEEKEND. THE MAIN CORE OF THIS FEATURE HAS GOOD MODEL  
CONSENSUS THAT IT WILL DRIFT THROUGH NEW ENGLAND BY SUNDAY AND  
THEN OVER ATLANTIC CANADA ON MONDAY. THE GUIDANCE AT LEAST THROUGH  
MONDAY IS AGREEABLE SUCH THAT A GENERAL MODEL BLEND CAN BE  
PREFERRED.  
 
   
..SHORTWAVE CROSSING THE NORTHERN PLAINS THROUGH SUNDAY
 
   
..ENERGY THEN DIGGING THROUGH THE MIDWEST/OH VALLEY ON MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
A SHORTWAVE CURRENTLY OVER THE NORTHERN HIGH PLAINS WILL DIVE  
SOUTHEAST ACROSS THE MIDWEST AND BE RACING ACROSS THE OH VALLEY BY  
LATE MONDAY. IT WILL THEN REACH THE MID-ATLANTIC COAST MONDAY  
NIGHT. THE 12Z NAM IS A STRONGER OUTLIER WITH THIS SYSTEM, AND SO  
A NON-NAM BLEND WILL BE PREFERRED.  
 
   
..SHORTWAVE CROSSING THE GREAT LAKES LATE MONDAY
 
   
..DROPPING DOWN ACROSS THE OH VALLEY ON TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z GFS/00Z CMC/00Z UKMET  
CONFIDENCE: AVERAGE  
 
IN THE WAKE OF THE SHORTWAVE ON MONDAY, A NEW NORTHERN STREAM  
SHORTWAVE WILL DROP SOUTHEAST AND CROSS THE OH VALLEY ON TUESDAY.  
THE 12Z NAM TENDS TO BE A BIT STRONG WITH THIS SYSTEM, BUT THE 00Z  
ECMWF APPEARS TO BE TOO WEAK. BETTER MODEL CLUSTERING RESIDES WITH  
THE 12Z GFS/00Z CMC AND 00Z UKMET, SO A BLEND OF THESE SOLUTIONS  
WILL BE PREFERRED.  
 
   
..SPLIT FLOW TROUGH CROSSING THE WEST COAST ON SUNDAY
 
   
..ENERGY EJECTING THROUGH THE SOUTHWEST AND PLAINS BY TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z NAM/GFS AND 00Z ECMWF BLEND...NORTHERN STREAM  
NON-CMC BLEND...SOUTHERN STREAM  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE MODELS ALL TAKE A PROGRESSIVE SPLIT FLOW TROUGH ACROSS THE  
WEST COAST ON SUNDAY, WITH A SOUTHERN STREAM PORTION OF THE ENERGY  
THEN DROPPING DOWN ACROSS THE SOUTHWEST AND AMPLIFYING INTO A  
CLOSED LOW AS IT APPROACHES THE SOUTHERN HIGH PLAINS BY EARLY  
TUESDAY. MEANWHILE, THE NORTHERN STREAM COMPONENT OF THE TROUGH  
WILL BE OVER THE NORTHERN HIGH PLAINS. THE 00Z CMC IS AN OUTLIER  
WITH BOTH NORTHERN AND SOUTHERN STREAM COMPONENTS AS IT IS LIKELY  
TOO STRONG/SLOW AND TOO FAR NORTH WITH THE SOUTHERN STREAM ENERGY,  
AND TOO SLOW WITH THE ENERGY IN THE NORTHERN STREAM. THE 00Z UKMET  
ALSO APPEARS TO BE TOO SLOW/DEEP WITH ITS HANDLING OF THE NORTHERN  
STREAM ENERGY. A NON-CMC BLEND WILL BE PREFERRED WITH THE SOUTHERN  
STREAM EVOLUTION, AND A NAM/GFS/ECMWF BLEND WITH THE NORTHERN  
STREAM EVOLUTION.  
 
   
..PROGRESSIVE UPPER TROUGH OVER THE PACIFIC NORTHWEST TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z NAM AND 00Z UKMET/ECMWF  
CONFIDENCE: AVERAGE  
 
YET ANOTHER IN A SERIES OF PACIFIC SHORTWAVE TROUGHS WILL ARRIVE  
ON TUESDAY ACROSS THE PACIFIC NORTHWEST. THE 12Z GFS AND 00Z CMC  
ARE DEEPER OUTLIERS WITH THIS SYSTEM, ALTHOUGH THERE IS SOME  
SUPPORT FOR A RELATIVELY DEEPER SOLUTION FROM THE GEFS ENSEMBLE  
SUITE. THE 12Z NAM AND 00Z UKMET/ECMWF SOLUTIONS ARE ALL WEAKER  
AND HAVE BETTER SUPPORT FROM THE CMCE/ECENS SUITES. SO, WILL  
PREFER THE RELATIVELY WEAKER CONSENSUS.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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