323  
FXUS10 KWNH 260734  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
234 AM EST SUN JAN 26 2020  
 
VALID JAN 26/0000 UTC THRU JAN 29/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..DEEP CLOSED LOW MOVING ACROSS THE NORTHEAST THROUGH SUNDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
OUTSIDE OF THE 00Z NAM WHICH LAGS WEST OF THE CONSENSUS, THE  
GLOBAL MODELS ARE IN VERY GOOD AGREEMENT WITH THE STRONG UPPER LOW  
MOVING INTO CANADA MONDAY AND THEN OPENING BEFORE EJECTING TOWARDS  
NEWFOUNDLAND TUESDAY.  
 
...SHORTWAVE DIGGING FROM THE NORTHERN PLAINS TODAY TO OFF THE  
MID-ATLANTIC COAST TUESDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
 
07Z UPDATE: THE DISCREPANCY BETWEEN THE NCEP AND NON-NCEP CAMPS  
FROM THE PRIOR SOLUTIONS HAS MOSTLY DISAPPEARED, LEAVING GOOD  
CONSENSUS AMONG THE GLOBAL SUITE. A GENERAL MODEL BLEND IS USABLE.  
 
A SHARP SHORTWAVE DROPPING THROUGH THE NORTHERN PLAINS WILL DIVE  
QUICKLY SOUTHEAST AND ROUND THE BASE OF THE LONGWAVE TROUGH  
CENTERED OVER NEW ENGLAND. THIS FEATURE WILL MOVE QUICKLY THROUGH  
THE OHIO VALLEY AND BE OFF THE MID-ATLANTIC COAST BY TUESDAY. THE  
CMC IS A FAST/SHEARED OUTLIER COMPARED TO THE REMAINING GUIDANCE  
AND SHOULD NOT BE INCLUDED. OF THE REMAINING MODELS, THERE EXISTS  
AN NCEP VS NON-NCEP CAMP AS THE NCEP MODELS ARE A BIT STRONGER AND  
FASTER THAN THE NON-NCEP SOLUTIONS. THE ECENS AND GEFS ARE MORE IN  
LINE WITH THE SLOWER SOLUTIONS, SO FAVOR THE NON-NCEP CAMP FOR  
THIS FEATURE AS IT SHIFTS EAST THROUGH EARLY IN THE WEEK.  
 
...TROUGH LIFTING INTO THE WEST TODAY AND DEEPENING ACROSS THE  
SOUTHERN PLAINS BY TUESDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-CMC/UKMET BLEND  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
 
07Z UPDATE: WHILE THE OVERALL EVOLUTION IS PRETTY CONSISTENT AND  
AGREED UPON BY THE GLOBAL MODELS, SOME DISCREPANCIES ARE  
INCREASING WITH THE NORTHERN STREAM PORTION OF THE ENERGY BY DAY  
2. THE CMC AND UKMET FEATURE SIGNIFICANTLY MORE INTERACTION OF THE  
NORTHERN AND SOUTHERN STREAMS, WHILE THE REMAINING GUIDANCE KEEP  
THESE FEATURES SEPARATED WITH LITTLE INTERACTION THROUGH 84 HOURS.  
THE GFS IS ON THE WEAK SIDE OF THE ENVELOPE WITH THE SOUTHERN  
STREAM ENERGY, BUT IS WELL POSITIONED OTHERWISE SO CAN STILL BE  
INCLUDED BUT POTENTIALLY WITH SOMEWHAT LESS WEIGHT THAN THE  
ECMWF/NAM AND THE MEANS.  
 
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. THE 12Z CMC IS AN OUTLIER AS IT IS LIKELY TOO STRONG/SLOW  
AND TOO FAR NORTH WITH THE SOUTHERN STREAM ENERGY. THE 12Z UKMET  
ALSO APPEARS TO BE TOO SLOW/DEEP AND LIKE THE CMC TENDS TO SUPPORT  
A BIT MORE INTERACTION BETWEEN NORTHERN AND SOUTHERN STREAM  
TROUGHS LATE IN THE PERIOD. THE NAM/GFS AND ECMWF ALL FAVOR A BIT  
MORE STREAM SEPARATION AT LEAST THROUGH THIS PERIOD WITH JUST SOME  
SUBTLE NORTHERN/SOUTHERN STREAM TROUGH INTERACTION AT THE VERY END  
OF THE PERIOD AS THE ENERGY APPROACHES THE MS VALLEY. WILL PREFER  
A BLEND OF THE NAM/GFS AND ECMWF AT THIS TIME GIVEN THEY STILL  
TEND TO HAVE THE STRONGER ENSEMBLE SUPPORT.  
 
   
..TROUGH MOVING ONSHORE THE WEST TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF ECENS/GEFS MEANS  
CONFIDENCE: AVERAGE  
 
YET ANOTHER IN A SERIES OF PACIFIC SHORTWAVE TROUGHS WILL ARRIVE  
ON TUESDAY ACROSS THE PACIFIC NORTHWEST. THERE IS CONSIDERABLE  
SPREAD IN INTENSITY OF THIS FEATURE DESPITE REASONABLE AGREEMENT  
IN TIMING ON D3. THE ENSEMBLE MEANS ARE IN GENERALLY GOOD  
AGREEMENT AND ARE FAVORED OUTSIDE OF ANY OPERATIONAL MODEL WHICH  
SHOW A WIDE VARIATION IN SOLUTIONS IN THE FAST MID/UPPER FLOW.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
WEISS  
 

 
 
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