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FXUS10 KWNH 071844
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
144 PM EST WED DEC 07 2016

VALID DEC 07/1200 UTC THRU DEC 11/0000 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z MODEL EVALUATION INCLUDING FINAL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


CLOSED LOW TRACKING INTO QUEBEC ON THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.


SERIES OF LOW AMPLITUDE SHORTWAVE TRACKING FROM THE PLAINS TO THE
  EAST COAST THU AND FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW SIMILARLY WITH THE FIRST SHORTWAVE...PROGGED TO
REACH NEW ENGLAND THU AFTERNOON. THE 00Z CMC SHOWED DEEPER THAN
THE REMAINING MODEL CONSENSUS WITH A SECOND SHORTWAVE TROUGH
EXPECTED TO REACH THE EAST COAST ON FRI. THE 12Z CMC ADJUSTED
TOWARD THE CONSENSUS WITH THE SECOND SHORTWAVE AND WHILE MINOR
TIMING/STRENGTH DIFFERENCES REMAIN...ENOUGH AGREEMENT EXISTS TO
SUPPORT A GENERAL MODEL COMPROMISE AT THIS TIME.


SERIES OF STORM SYSTEMS IMPACTING THE WEST COAST THROUGH THE END OF
  THE WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 2/3 12Z GFS...1/3 00Z ECMWF BLEND
CONFIDENCE: BELOW AVERAGE

COMPARED TO YESTERDAY...THE GFS HAS TRENDED TOWARD THE GEFS/EC
MEANS REGARDING THE FIRST PIECE OF SHORTWAVE ENERGY FORECAST TO
REACH THE PACIFIC NORTHWEST THU EVENING ALONG WITH THE UPSTREAM
CLOSED LOW APPROACHING FROM THE WEST. CURRENTLY...THE 12Z GFS
LOOKS THE MOST REPRESENTATIVE OF THE ENSEMBLE MEANS REGARDING
HEIGHTS ALOFT AND THE SURFACE REFLECTION...ALTHOUGH A FAIR AMOUNT
OF SPREAD REMAINS IN THE ENSEMBLES...KEEPING CONFIDENCE BELOW
AVERAGE.

THE 12Z NAM APPEARS MORE AMPLIFIED AND A BIT FAST FRI EVENING
ALONG THE WEST COAST...WHILE THE 12Z ECMWF MADE A SIGNIFICANT
CHANGE TO CONTINUITY WITH A SLOWER OVERALL PROGRESSION TO THE
REMNANT CLOSED LOW OFF OF THE PACIFIC NORTHWEST COAST. THE 12Z
CMC/UKMET ARE SOMEWHERE IN BETWEEN THE 12Z NAM/GFS CAMP AND THE
12Z ECMWF CAMP. WHILE THE 00Z ECMWF COULD BE A BIT TOO WEAK WITH
ITS LOW-MID LEVEL REFLECTION OF THE CLOSED LOW NEARING THE PACIFIC
NORTHWEST FRI EVENING...IT IS CONSIDERED THE NEXT CLOSEST TO THE
PREFERENCE. GIVEN THE POOR RUN TO RUN CONTINUITY AND THE LATEST
ENSEMBLE CLUSTERING AWAY FROM THE 12Z ECMWF...WILL STICK WITH THE
PREVIOUS PREFERENCE OF THE 12Z GFS AND 00Z ECMWF...BUT WITH MORE
WEIGHT TOWARD THE GFS.


SHORTWAVE EMERGING OVER THE N-CNTRL PLAINS SAT EVENING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 2/3 12Z GFS...1/3 00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

DIFFERENCES NOTED IN THE ABOVE SECTION CARRYOVER DOWNSTREAM INTO
THE PLAINS WITH THE 12Z NAM MOST AMPLIFIED INTO THE PLAINS. THE
12Z PARALLEL NAM SUPPORTS A FLATTER WAVE...WITH LESS OF A SURFACE
REFLECTION COMPARED TO THE OPERATIONAL NAM...ALONG WITH A MAJORITY
OF THE LATEST ENSEMBLE SPAGHETTI HEIGHTS. THE 00Z ECMWF AND ITS
MEAN COULD BE A LITTLE TOO FLAT BUT GIVEN THE UPSTREAM
PREFERENCES...SOME OF THE ECMWF IS RECOMMENDED TO BE BLENDED WITH
THE 12Z GFS.

19Z UPDATE...THE 12Z ECMWF IS CONSIDERED A FLAT OUTLIER WITH THIS
SYSTEM...WHILE THE 12Z CMC/UKMET APPEAR TOO FAST/FLAT RESPECTIVELY
COMPARED TO THE PREFERENCE.


LINGERING ONSHORE FLOW INTO CALIFORNIA ON SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 2/3 12Z GFS...1/3 00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

BY SATURDAY AFTERNOON...THE ENSEMBLES SHOW A SPLIT OF
SOLUTIONS...WITH THE 00Z ECMWF ENSEMBLE MEMBERS AND 00Z UKMET
SHOWING A FLATTER FLOW INTO THE WEST COAST...WITH THE 12Z
GFS/NAM...06Z GEFS AND 00Z CMC SHOWING MORE RIDGING IN THE EASTERN
PACIFIC. GIVEN PREFERENCES ALONG THE WEST COAST WITH PREVIOUS
SYSTEMS AND TRENDS NOTED TO SHOW MORE RIDGING...WILL HEDGE THE
PREFERENCE TOWARD THE 12Z GFS...WHILE BLENDING IN SOME OF THE
FLATTER 00Z ECMWF. THIS IDEA IS SUPPORTED BY THE 06Z GEFS
MEAN...SHOWING A FLATTER PATTERN ALONG THE WEST COAST BY 00Z/11
COMPARED TO THE 00Z CMC AND 12Z GFS.

19Z UPDATE...GIVEN THE LACK OF SUPPORT FOR THE 12Z ECMWF DESCRIBED
IN ABOVE SECTIONS...WILL STAY WITH THE PREVIOUS PREFERENCE OF THE
12Z GFS/00Z ECWMF WITH MORE WEIGHT TOWARD THE GFS.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

OTTO

$$





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