049  
FXUS10 KWNH 310639  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
238 AM EDT SUN MAY 31 2020  
 
VALID MAY 31/0000 UTC THRU JUN 03/1200 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION INCLUDING INITIAL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
UPPER LEVEL TROUGH AND COLD FRONT ACROSS THE EASTERN U.S.  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 00Z TUESDAY, THEN 12Z  
ECMWF/GFS/UKMET BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
AN AMPLIFIED UPPER LEVEL TROUGH WILL CONTINUE TO BUILD IN ACROSS  
THE EASTERN U.S. THROUGH THE BEGINNING OF THE WEEK, WITH THE  
SURFACE COLD FRONT CONTINUING TO MOVE FARTHER OFFSHORE AND A HIGH  
QUALITY AIRMASS SETTLING IN ACROSS MUCH OF THE REGION. SIMILAR TO  
LAST NIGHT, THE MODELS ARE IN VERY GOOD AGREEMENT THROUGH ABOUT  
00Z TUESDAY WITH THE CMC REMAINING SLIGHTLY WEAKER WITH THE  
TROUGH. BY TUESDAY MORNING, AN UPPER LOW IS LIKELY TO EVOLVE FROM  
THE TROUGH OVER THE NOVA SCOTIA REGION, WITH THE GFS AND UKMET  
INDICATING THE BEST POTENTIAL FOR THIS BY 00Z WEDNESDAY. A BLEND  
OF THE ECMWF, GFS, AND UKMET SHOULD WORK WELL BEYOND 00Z TUESDAY  
 
 
UPPER LEVEL LOW SLOWLY LIFTING FROM NORTHERN MEXICO INTO THE  
SOUTHERN PLAINS SATURDAY-TUESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
 
THE MODELS ARE IN GENERALLY GOOD AGREEMENT INDICATING A BROAD  
UPPER LOW LIFTING NORTH FROM NORTHERN MEXICO INTO WEST TEXAS BY  
TUESDAY MORNING, BEFORE CONTINUING NORTHEAST TOWARDS OKLAHOMA ON  
TUESDAY NIGHT. THERE IS NOT MUCH OF A SURFACE REFLECTION OF THIS  
IN TERMS OF THE SEA LEVEL PRESSURE FIELDS. A GENERAL MODEL BLEND  
WILL SUFFICE FOR THIS UPPER LEVEL LOW AND TROUGH.  
 
SHORTWAVE LIFTING ACROSS THE PACIFIC NORTHWEST AND THEN ACROSS  
SOUTHERN CANADA  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND  
CONFIDENCE: AVERAGE  
 
OVERALL, MODELS ARE IN GOOD AGREEMENT SHOWING A STRONG SHORTWAVE  
OVER OREGON AND LIFTING NORTHEAST ACROSS WASHINGTON AND THEN  
ALBERTA BY SUNDAY NIGHT. MODELS REMAIN IN GOOD AGREEMENT INTO  
EARLY MONDAY AS THE SYSTEM CONTINUES FARTHER EAST ACROSS  
SOUTH-CENTRAL CANADA. SIGNIFICANT MODEL DIFFERENCES DO NOT EVOLVE  
UNTIL EARLY TUESDAY AS SYSTEM BEGINS TO MOVE SOUTH OF HUDSON BAY.  
AS THE SYSTEM BEGINS TO ROUND THE TOP OF THE UPPER RIDGE, THE  
UKMET BECOMES A NOTED OUTLIER WITH A CLOSED SYSTEM DEVELOPING  
SOUTH OF HUDSON BAY AND MUCH SLOWER THAN THE OTHER GUIDANCE.  
 
UPPER LEVEL TROUGH MOVING FROM THE PACIFIC NORTHWEST TO THE  
NORTHERN PLAINS AND UPPER MIDWEST MONDAY-TUESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 12Z MONDAY THEN,  
GFS/ECMWF COMPROMISE 12Z MONDAY-00Z WEDNESDAY  
CONFIDENCE: AVERAGE  
 
WITH RESPECT TO TIMING, THE MODELS ARE IN GENERALLY GOOD AGREEMENT  
THROUGH EARLY MONDAY AS THE SYSTEM MOVES EAST FROM THE EASTERN  
PACIFIC INTO THE PACIFIC NORTHWEST. HOWEVER, DIFFERENCES QUICKLY  
DEVELOP AS THE SYSTEM MOVES DOWNSTREAM, WITH THE UKMET, ECMWF AND  
THE 00Z EC ENSEMBLE MEAN BECOMING NOTABLY FASTER THAN THE NCEP  
GUIDANCE THROUGH THE NORTHERN ROCKIES INTO THE PLAINS AND UPPER  
MIDWEST. WHILE THE GFS IS STILL AMONG THE SLOWER SOLUTIONS, IT  
HAS TRENDED FASTER COMPARED TO ITS 00Z AND PREVIOUS 12Z SOLUTIONS.  
AND WHILE STILL FASTER THAN THE GFS, THE 12Z ECMWF IS SLOWER THAN  
ITS 00Z RUN, SUGGESTING THE TWO MODELS MAY BE MOVING TOWARD A  
CONSENSUS.  
 
CUTOFF LOW DEVELOPING WEST OF SOUTHERN CALIFORNIA AND NORTHERN  
BAJA MONDAY-TUESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: UKMET/ECMWF/12Z EC ENSEMBLE MEAN  
CONFIDENCE: AVERAGE  
 
ENERGY DROPPING SOUTHEAST ACROSS THE EASTERN PACIFIC IS EXPECTED  
TO DEVELOP A CLOSED LOW OFF OF THE SOUTHERN CALIFORNIA AND  
NORTHERN BAJA COASTS EARLY NEXT WEEK. LATEST GUIDANCE SHOWS SOME  
DIFFERENCES WITH RESPECT TO THE POSITION OF THE LOW'S CENTER, WITH  
THE NCEP GUIDANCE GENERALLY A LITTLE EAST OF THE UKMET, ECMWF AND  
THE 12Z EC ENSEMBLE MEAN. TRENDS IN THE GFS SUPPORT LEANING  
TOWARD THE UKMET, ECMWF AND 12Z EC MEAN.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
HAMRICK  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page