839  
FXUS10 KWNH 140625  
PMDHMD  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
224 AM EDT SUN JUN 14 2020  
 
VALID JUN 14/0000 UTC THRU JUN 17/1200 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..CLOSED LOW DEVELOPING IN SOUTHERN APPALACHIANS MON/TUES
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
07Z UPDATE: LITTLE ADJUSTMENTS, SUCH A NORTHWARD SHIFT,EVER SO  
SLIGHTLY BY DAY 3 IN THE ECMWF AND CMC, SUGGEST STRONGER OVERALL  
AGREEMENT AND SUPPORT OF CONTINUED GENERAL MODEL BLEND PREFERENCE  
AT ABOVE AVERAGE CONFIDENCE.  
 
---PRIOR DISCUSSION---  
GOES-E WV DEPICTS THE A SMALL COMPACT SHORTWAVE OVER LOWER LAKE  
MICHIGAN AND THIS IS THE FEATURE THAT WILL DESCEND THROUGH THE  
OHIO VALLEY SLOWLY AND EXPAND INTO THE FAIRLY STATIC CLOSED LOW  
ACROSS THE SOUTHEAST THROUGH THE EARLY PORTION OF NEXT WEEK.  
OVERALL, DIFFERENCES APPEAR TO BE GETTING SMALLER, THOUGH THE  
ECMWF/CMC ARE BOTH A BIT SOUTH AND EAST OF THE NAM/GFS WITH THE  
UKMET SPLIT BETWEEN. OVERALL, THE DIFFERENCES WILL BE DRIVEN BY  
MESOSCALE AND CONVECTIVE PROCESSES THAT CAN BE HANDLED WITHIN A  
GENERAL MODEL BLEND. CONFIDENCE IS ABOVE AVERAGE  
 
...INTERACTION OF SHORTWAVE LIFTING THROUGH SW CANADA WITH A  
CLOSED LOW ADVECTING ONSHORE WASHINGTON SUNDAY...   
..SECONDARY CLOSED LOW MOVING INTO THE NORTHWEST TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 16.00Z  
00Z ECMWF/CMC/NAM THEREAFTER  
CONFIDENCE: ABOVE AVERAGE TRANSITIONING TO AVERAGE AFTER 48HRS  
 
07Z UPDATE: THERE WAS A SLIGHT TRENDING TOWARD A DEEPER SOLUTION  
BY THE 00Z ECWMF AND CMC, NEARING THE NAM TO PERHAPS SUGGEST SOME  
MINOR INCLUSION AT THE END OF DAY 2 INTO AND THROUGH DAY 3.  
HOWEVER, THIS ONLY MAKES THE DIFFERENCE OF THE FASTER GFS EVEN  
MORE STARK. THE 00Z UKMET REMAINS AMPLIFIED BUT HAS SLID EAST A  
BIT AWAY FROM THE NAM AND NOW ECMWF/CMC. AS SUCH WILL ADD THE NAM  
AT LOWER WEIGHT TO THE PREFERENCE AFTER 16.00Z WITH CONFIDENCE  
REMAINING AVERAGE AFTER 48HRS.  
 
---PRIOR DISCUSSION---  
THREE MAIN SHORTWAVE FEATURES WILL HELP DEFINE A LARGER SCALE GYRE  
SET-UP THAT DEVELOPS ACROSS SW CANADA INTO THE PACIFIC NORTHWEST  
AND NORTHERN US ROCKIES ACROSS THE NEXT FEW DAYS. THE INITIAL  
SHORTWAVE THAT EMERGED FROM CA IS ADVANCING THROUGH THE GREAT  
BASIN AND ELONGATING THE CLOSED LOW ALONG WA COAST/VANCOUVER  
ISLAND AT THIS TIME. THE BINARY INTERACTION HAS STARTED TO BECOME  
MUCH MORE FOCUSED AND AGREED UPON THOUGH THERE REMAINS SOME MINOR  
MODEL SPREAD AS THE LEAD SHORTWAVE AMPLIFIES ACROSS SW CANADA AND  
PRESSES THE FRONTAL ZONE OUT OF THE HIGH PLAINS INTO THE NORTHERN  
PLAINS THROUGH MONDAY. THE 00Z GFS IS STILL A TAD FASTER, AND  
THEREFORE TIGHTER/WEST WITH THE AMPLIFYING SHORTWAVE BUT OVERALL  
THE PLACEMENT/TIMING OF THE SYNOPTIC FEATURES HAVE RESOLVED TO  
SUPPORT A GENERAL MODEL BLEND THROUGH 48HRS, INCLUDING THE  
ACCELERATION OF THE OLDER CLOSED LOW MOVING THROUGH THE NW INTO  
THE HIGH PLAINS MONDAY.  
 
THEREAFTER, THE MODEL SPREAD BEGINS TO INCREASE WITH THE APPROACH  
OF THE NEXT SHORTWAVE OUT OF THE NORTH PACIFIC. THIS IS A  
COMPACT SHORTWAVE/CLOSED LOW, THAT IS ACTUALLY QUITE PROGRESSIVE  
THROUGH THE GULF OF AK. A SMALL TIMING WOBBLE WITHIN THE BROADER  
CYCLONIC FLOW ON MONDAY, WILL HELP TO KICK THE NOSE OF THE JET  
THROUGH THE PACIFIC NW AND HELP TO EXPAND THE LARGER  
GYRE/INTERACTION WITH THE SW CANADA SYSTEMS' ENERGY. THIS WILL  
ALSO SUPPORT A STRONG SURFACE WAVE RESPONSE TUESDAY ACROSS WY INTO  
THE NORTHERN PLAINS, WITH THE BULK/CORE OF THE CLOSE LOW STILL  
REMAINING UPSTREAM MAINTAINING/DIGGING THE WESTERN TROF BY 00Z  
WED. THE 00Z GFS SHOWS SOME BIAS OF PRESSING THE INITIAL  
HEIGHT-FALLS OUT FAST, LEADING TO A EASTWARD SHIFT OF THE FRONTAL  
ZONE ACROSS THE PLAINS AS WELL AS AN ACCELERATION OF THE SURFACE  
WAVE NORTH INTO CANADA LATER IN THE DAY. THIS SEEMS TOO  
AGGRESSIVE AND IN LINE WITH TYPICAL NEGATIVE BIAS. THE 00Z NAM  
AND 12Z UKMET ARE A BIT SLOWER BUT ALSO MUCH MORE AMPLIFIED  
DIGGING THE TROF THROUGH THE SNAKE RIVER PLAINS INTO THE NORTHERN  
ROCKIES AT THE SAME TIME, WHILE THE ECMWF/CMC ARE MORE MIDDLE  
GROUND WITHIN THE ENSEMBLE SUITE AND MORE IN-LINE WITH THE FLOW  
PATTERN/TIMING IN INTERACTION WITH THE PRECURSORY WAVE. AS SUCH  
WILL FAVOR THE 00Z ECMWF/CMC OVER THE GFS/NAM/UKMET AFTER 16.00Z  
(48HRS). CONFIDENCE IS ABOVE AVERAGE PRIOR TO 16.00Z BUT BECOMING  
AVERAGE THEREAFTER GIVEN UNCERTAINTY IN MAGNITUDE OF SHORTWAVE  
INTERACTION PLACEMENT THROUGH COMPLEX TERRAIN IN A VERY  
PROGRESSIVE FLOW REGIME.  
 
GALLINA  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 

 
 
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