848
FXUS10 KWNH 061856
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT WED MAY 06 2020
VALID MAY 06/1200 UTC THRU MAY 10/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...UPPER TROUGH IMPACTING THE MID-ATLANTIC/NEW ENGLAND THROUGH
THURSDAY...
...CONSOLIDATING/DEEPENING SURFACE LOW PRESSURE OFF THE EAST COAST
THROUGH THURSDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS BRING A RELATIVELY STRONG UPPER TROUGH THROUGH THE OH
VALLEY AND ACROSS THE MID-ATLANTIC AND NEW ENGLAND THROUGH EARLY
THURSDAY, WHICH INCLUDES A CLOSED MID-LEVEL LOW CENTER CROSSING
FROM EASTERN OH THROUGH NORTH-CENTRAL PA AND THEN UP ACROSS
SOUTHEAST NEW ENGLAND. THE MODEL SPREAD IS QUITE MINIMAL WITH
THIS. AT THE SURFACE, MULTIPLE LOW CENTERS ARE EXPECTED TO
CONSOLIDATE OFF THE EAST COAST AND DEEPEN INTO ONE DOMINANT CENTER
THAT LIFTS AWAY FROM NEW ENGLAND THURSDAY. GIVEN ONLY MODEST
SPREAD IN THE MASS FIELDS, A GENERAL MODEL BLEND WILL BE PREFERRED.
..AMPLIFYING SHORTWAVE CROSSING THE NORTHWEST U.S. TODAY
..ENERGY DIGGING ACROSS THE PLAINS/MIDWEST THURSDAY
..PHASING WITH STRONG CANADIAN TROUGH/VORTEX
..DEEPENING SURFACE LOW FROM THE OH VALLEY TO THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/GFS/ECMWF AND 00Z ECENS MEAN
CONFIDENCE: AVERAGE
A VIGOROUS SHORTWAVE ENTERING THE NORTHWEST TODAY WILL AMPLIFY OUT
ACROSS MT THROUGH TONIGHT AND DIG SOUTHEAST THROUGH THE REMAINDER
OF THE NORTHERN PLAINS AND MIDWEST THROUGH THURSDAY. BY FRIDAY,
THE ENERGY WILL BE CROSSING THE OH VALLEY AND WILL BE BEGIN TO
PHASE WITH VERY STRONG NORTHERN STREAM HEIGHT FALLS/TROUGHING
ASSOCIATED WITH A VORTEX SETTLING SOUTH OVER EASTERN ONTARIO AND
SOUTHWEST QUEBEC. THIS WILL LEAD TO STRENGTHENING LOW PRESSURE UP
ACROSS THE OH VALLEY ALONG A FRONTAL BOUNDARY, AND THIS LOW CENTER
WILL THEN CROSS THE MID-ATLANTIC BY FRIDAY EVENING. ON SATURDAY,
THE COUPLING/PHASED RESULTANT OF ENERGY MOVING INTO THE NORTHEAST
WILL YIELD A HIGHLY ANOMALOUS CLOSED LOW AND ASSOCIATED UPPER
TROUGH (500 MB HEIGHTS 3 TO 4 STANDARD DEVIATIONS BELOW NORMAL)
WITH A RAPIDLY DEEPENING SURFACE LOW LIFTING UP ACROSS OR JUST
OFFSHORE OF COASTAL NEW ENGLAND.
THE 12Z GUIDANCE HAS COLLECTIVELY TRENDED STRONGER AND FARTHER
NORTH WITH THE LOW TRACK OF THE SYSTEM, WITH THE NAM ON THE
STRONGER SIDE OF THE MODEL SPREAD. THE CMC AND ECMWF HAVE THEIR
LOW TRACKS VERY CLOSE TO THAT OF THE NAM, WITH THE UKMET AND GFS
CLUSTERED A TAD FARTHER SOUTH AND EAST BY COMPARISON. THE UKMET IS
OVERALL THE WEAKEST DETERMINISTIC SOLUTION WITH THE LOW CENTER.
THE 12Z GEFS MEAN DID TREND STRONGER AND FARTHER NORTH WITH ITS
LOW CENTER, BUT STILL IS WEAKER THAN THE NAM/GFS/ECMWF CLUSTER AND
THE ECENS MEAN. SO, BASED ON THE LATEST TRENDS AND MODEL
CLUSTERING, THE PREFERENCE WILL BE THE SAME AS BEFORE, EXCEPT TO
SWAP OUT THE 00Z ECMWF FOR THE 12Z ECMWF. THUS A BLEND OF THE 12Z
NAM/GFS/ECMWF AND THE 00Z ECENS MEAN AT THIS POINT IS PREFERRED.
...SHORTWAVE/SURFACE LOW IMPACTING THE NORTHERN ROCKIES AND
NORTHERN PLAINS BY FRIDAY/SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: AVERAGE
DOWNSTREAM OF A SHARP AND ELONGATED MID-LEVEL RIDGE IN PLACE OVER
WESTERN NORTH AMERICA BY FRIDAY AND SATURDAY, A SHORTWAVE IS
EXPECTED TO DROP SOUTHEAST THROUGH CENTRAL AND SOUTHERN CANADA AND
OVER PORTIONS OF THE NORTHERN ROCKIES AND NORTHERN PLAINS. THE
LATEST GUIDANCE ALSO SUGGESTS A WAVE OF LOW PRESSURE WILL BE
ATTENDANT TO THIS SYSTEM. THE 12Z UKMET AND 12Z CMC ARE THE
SLOWEST SOLUTIONS, WITH THE 12Z ECMWF NOW THE FASTEST. THE 12Z NAM
AND 12Z GFS CLUSTER IN BETWEEN SLOWER AND FASTER CAMPS. THE 12Z
GFS GENERALLY IS CLOSEST TO THE MODEL CONSENSUS AT THIS POINT, AND
SINCE IT HAD GOOD AGREEMENT FROM THE 00Z ECMWF, THE PRIOR MODEL
PREFERENCE WILL BE MAINTAINED FOR THE TIME BEING.
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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