413
FXUS10 KWNH 091837
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
237 PM EDT SAT MAY 09 2020
VALID MAY 09/1200 UTC THRU MAY 13/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..EXITING DEEP LAYER CYCLONE IMPACTING THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS ARE IN VERY GOOD AGREEMENT WITH THE DETAILS OF THE DEEP
LAYER CYCLONE IMPACTING THE NORTHEAST TODAY, WHICH WILL BE LIFTING
OFF TO THE NORTHEAST ACROSS THE CANADIAN MARITIMES THROUGH TONIGHT
AND SUNDAY. A GENERAL MODEL BLEND WILL BE PREFERRED.
...COMPACT SHORTWAVES/SURFACE LOW IMPACTING THE NORTHERN PLAINS
AND MIDWEST THIS WEEKEND...
...ENERGY AMPLIFYING FROM THE OH VALLEY TO THE NORTHEAST MON AND
TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND...THROUGH 48 HOURS
12Z ECMWF/00Z ECENS MEAN BLEND...AFTER 48 HOURS
CONFIDENCE: AVERAGE
THE GUIDANCE TAKES THE VIGOROUS COMPACT SHORTWAVE AND ASSOCIATED
SURFACE LOW OVER THE NORTHERN PLAINS SOUTHEASTWARD ACROSS THE
MIDWEST GOING THROUGH SUNDAY. ON MONDAY THIS LEAD ENERGY AND A
FAST-MOVING SECONDARY SHORTWAVE IN ITS WAKE WILL CONSOLIDATE AND
TRANSIT THE OH VALLEY. AS THE ENERGY ROUNDS THE BASE OF THE LARGER
SCALE TROUGHING THAT WILL BE PERSISTING FROM THE GREAT LAKES
REGION INTO MUCH OF SOUTH-CENTRAL AND SOUTHEAST CANADA, THIS OH
VALLEY ENERGY SHOULD AMPLIFY, AND BY TUESDAY ALL OF THE MODELS
SUPPORT THE IDEA OF A NEGATIVELY TILTING SHORTWAVE AND POSSIBLE
CLOSED MID-LEVEL LOW CROSSING NEW ENGLAND ALONG WITH AN
INTENSIFYING SURFACE LOW CENTER. THE GUIDANCE IS IN GOOD AGREEMENT
THROUGH ABOUT 48 HOURS, BUT THEREAFTER THE 12Z NAM SUGGESTS
STRONGER SHORTWAVE AMPLIFICATION AND A SURFACE LOW THAT TENDS TO
TRACK A TAD LEFT OF THE MODEL CONSENSUS AS IT CROSSES NEW ENGLAND
BY 72 HOURS. THE 12Z GFS ALSO BECOMES MORE PROGRESSIVE WITH THE
ENERGY THAN ANY OTHER MODEL BY THAT TIME, AND THE 12Z CMC IS SEEN
AS BEING A BIT SLOW. THE CMC DID SHIFT ITS LOW TRACK A BIT TO THE
EAST OF THE MODEL CONSENSUS AS WELL. MEANWHILE, THE 12Z UKMET
SHIFTED ITS LOW TRACK A BIT FARTHER WEST. THE MODEL CONSENSUS
BEYOND 48 HOURS, TENDS TO BE BEST SUPPORTED BY THE 12Z ECMWF WHICH
IS HANGING ON TO GOOD CONTINUITY FROM ITS 00Z RUN. THE ECMWF IS
WELL SUPPORTED BY THE 00Z ECENS MEAN TOO. SO AT THIS POINT, A
GENERAL MODEL BLEND WILL BE PREFERRED THROUGH 48 HOURS, FOLLOWED
BY A BLEND OF THE ECMWF/ECENS MEAN CAMP.
..SHORTWAVE ENERGY CROSSING SOUTHERN CA THIS WEEKEND
..ENERGY SHEARING ACROSS THE SOUTHERN PLAINS BY TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS
NON-NAM BLEND...AFTER 60 HOURS
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW A WEAK SHORTWAVE CROSSING SOUTHERN CA BY LATER
TODAY, AND THEN THE DESERT SOUTHWEST ON SUNDAY. THE ENERGY IS THEN
EXPECTED TO GRADUALLY SHEAR OFF TO THE EAST AND REACH THE SOUTHERN
PLAINS BY TUESDAY. MODEL SPREAD IS VERY MODEST THROUGH ABOUT 60
HOURS, BUT THEREAFTER THE 12Z NAM LEANS A BIT STRONGER THAN THE
WELL-CLUSTERED GLOBAL MODELS. SO, A GENERAL MODEL BLEND WILL BE
PREFERRED THROUGH 60 HOURS, FOLLOWED BY A NON-NAM BLEND THEREAFTER.
..UPPER TROUGH/CLOSED LOW APPROACHING THE WEST COAST BY TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
AN UPPER TROUGH AND ASSOCIATED CLOSED LOW WILL BE APPROACHING AND
POSSIBLY CROSSING THE WEST COAST BY TUESDAY AS THE LARGER SCALE
BLOCKING PATTERN ACROSS WESTERN NORTH AMERICA BEGINS TO BREAK
DOWN. THE 12Z NAM IS THE FASTEST TO BRING THE HEIGHT FALLS INLAND
ACROSS THE WEST COAST. THE 12Z GFS AND 12Z ECMWF SOLUTIONS ARE A
LITTLE SLOWER AND ALSO HAVE THEIR CLOSED LOW FEATURES A LITTLE
NORTH OF THE NAM POSITION BY THE END OF THE PERIOD. THE 12Z CMC IS
JUST A TAD WEAKER WITH THE ENERGY AND IS PERHAPS JUST SLIGHTLY
NORTH OF THE GFS/ECMWF CAMP. MEANWHILE, THE 12Z UKMET IS THE MOST
OUT OF PHASE AND THE SLOWEST WITH ITS CLOSED LOW EVOLUTION TOWARD
THE WEST COAST. NEVERTHELESS, ALL OF THE MODELS INCREASE THE
ONSHORE FLOW INTO THE WEST COAST, ESPECIALLY FROM NORTHERN CA TO
THE PACIFIC NORTHWEST AS SURFACE LOW PRESSURE LIFTS NORTHEAST UP
OFF THE COAST. BASED ON VERY GOOD MODEL MASS FIELD CLUSTERING AND
ENSEMBLE SUPPORT, A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED
AT THIS POINT.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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