874
FXUS10 KWNH 061655
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1254 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 AND 00Z ECMWF/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 NAM AND TO AN EXTENT THE 12Z GFS HAVE BOTH TRENDED NORTH
WITH THEIR RESPECTIVE SURFACE LOW TRACKS FROM THE OH VALLEY TO THE
NORTHEAST, BUT ARE MORE NOTABLY STRONGER THAN THEIR PREVIOUS RUNS.
THE 00Z ECMWF AND 00Z ECENS MEAN GENERALLY SUPPORT THE NAM LOW
TRACK, WITH THE GFS A BIT FARTHER SOUTH. HOWEVER, THE
GFS/ECMWF/ECENS MEAN CLUSTER IS A BIT WEAKER THAN THE NAM, AND BY
SATURDAY, THE NAM ENDS WITH A LOW TRACK FARTHEST TO THE WEST WITH
RESPECT TO NEW ENGLAND. MEANWHILE, THE 00Z UKMET AND MUCH MORE SO
THE 00Z CMC, ARE FLATTER/WEAKER SOLUTIONS BY COMPARISON AND HAVE A
LOW TRACK A BIT FARTHER OFFSHORE RELATIVE TO NEW ENGLAND. THE 06Z
GEFS MEAN ALSO IS A NOTABLY WEAK OUTLIER AT THIS POINT, AND
ESPECIALLY GIVEN THE LATEST 12Z TRENDS. SO, AT THIS POINT, A BLEND
OF THE 12Z NAM/GFS AND THE 00Z ECMWF/ECENS MEAN WILL BE PREFERRED
WITH THE EVOLUTION OF THIS SYSTEM.
...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 00Z CMC AND 00Z UKMET ARE THE
SLOWEST AND DEEPEST SOLUTIONS OVERALL, WITH THE 12Z NAM THE
FASTEST AND WEAKEST. THE 12Z GFS AND 00Z ECMWF ARE CLUSTERED IN
BETWEEN. A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED AT THIS
TIME TO APPROXIMATE THE MODEL CONSENSUS.
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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