151
FXUS10 KWNH 051834
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 PM EDT TUE MAY 05 2020
VALID MAY 05/1200 UTC THRU MAY 09/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL MODEL EVALUATION INCLUDING FINAL PREFERENCES AND
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...700 MB LOW TRACKING ACROSS THE NORTHERN MID ATLANTIC TO
SOUTHEAST NEW ENGLAND WED EVENING AND INTO THE OFFSHORE WATERS WED
NIGHT NIGHT-THU...
...SURFACE LOW DEVELOPMENT OVER NORTH CAROLINA TUE NIGHT AND OFF
THE MID ATLANTIC COAST WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 06Z GFS/12Z ECMWF/12 NAM/00Z CANADIAN
GLOBAL
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS SHOW A 500 MB TROUGH CROSS THE GREAT LAKES AND OH
VALLEY, WITH A TRIPLE POINT LOW DEVELOPING OVER NORTH CAROLINA AND
GRADUALLY STRENGTHENING AS IT MOVES OFF THE MID ATLANTIC COAST AND
JUST SOUTHEAST OF THE 40N 70W BENCHMARK. THE 12Z NAM/06Z GFS/12Z
ECMWF CLUSTER WELL SO A BLEND OF THESE SOLUTIONS IS PREFERRED.
THE LOWEST CONFIDENCE IS IN THE 12Z UKMET, AS ITS 700-500 MB WAVE
IS NOT AS AMPLIFIED AS THE MAJORITY MODEL/ENSEMBLE CLUSTER, WITH
EVEN THE ENSEMBLE MEANS MORE AMPLIFIED.
...MID-LEVEL SHORTWAVE MOVING FROM PACIFIC NORTHWEST COAST TUESDAY
NIGHT ACROSS THE NORTHERN ROCKIES WEDNESDAY NIGHT, NORTHERN PLAINS
THURSDAY, THEN THE MS VALLEY TO OHIO VALLEY FRIDAY...
...COLD FRONT DROPPING SOUTHWARD THROUGH THE GREAT PLAINS ON
THURSDAY AND LOW PRESSURE DEVELOPING ON THE FRONT IN THE OH VALLEY
FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 06Z GFS, 12Z NAM, 09Z SREF MEAN BLEND
CONFIDENCE: AVERAGE
THE MODELS INDICATE A DEEP LAYER TROUGH MOVES ONSHORE AND CROSS
THE PACIFIC NORTHWEST, WITH AN EMBEDDED 700 MB CIRCULATION THAT
DEVELOPS, MOVES ACROSS MT AND THEN SD, THEN MOVES DOWNSTREAM INTO
THE MID MS VALLEY AND OHIO VALLEY. THE 12Z UKMET AND 12Z ECMWF
TRENDED TOWARDS A SLIGHTLY MORE AMPLIFIED WAVE, IN THE DIRECTION
OF THE NAM AND SREF MEAN.
THE MODELS HAVE GOOD TIMING AGREEMENT AS THE 700 MB WAVE CROSS ES
THE MS VALLEY AND OH VALLEY, BUT THE NAM AND PARTICULARLY 12Z GFS
HAVE A HIGHER AMPLITUDE/SHORTER WAVELENGTH TROUGH THAN THE
ECMWF/UKMET/CANADIAN GLOBAL.
THE MODELS OCCASIONALLY HAVE A BIAS OF WEAKENING CLOSED LOWS TOO
FAST, SO I WOULD NOT DISMISS THE STRONGER NAM/GFS. GIVEN THE 12Z
GFS PRODUCES THE STRONGEST LOW PRESSURE ALONG THE FRONT IN THE
OHIO VALLEY, PREFERENCE IS GIVEN TO THE SLIGHTLY WEAKER 06Z GFS
RUN, WHICH CLUSTERS BETTER WITH THE NAM.
SINCE THE CANADIAN/ECMWF/UKMET ALL TRENDED TOWARDS THE NAM AND 06Z
GFS, THOSE SOLUTIONS WERE GIVEN MORE WEIGHTING.
PETERSEN
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page