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934
FXUS10 KWNH 071700
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MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM 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 NAM/GFS EVALUATION INCLUDING PRELIMINARY 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: NON 00Z CMC BLEND
CONFIDENCE: AVERAGE

THE MODELS SHOW SIMILARLY WITH THE FIRST SHORTWAVE...PROGGED TO
REACH NEW ENGLAND THU AFTERNOON. THE 00Z CMC SHOWS DEEPER THAN THE
REMAINING MODEL CONSENSUS WITH A SECOND SHORTWAVE TROUGH EXPECTED
TO REACH THE EAST COAST ON FRI. GIVEN A LACK OF SUPPORT FOR THE
CMC WITH THE SECOND SHORTWAVE...A NON 00Z CMC BLEND IS RECOMMENDED.


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 00Z CMC IS THE FLATTEST/WEAKEST
AND LEAST SUPPORTED DETERMINISTIC MODEL. THE 00Z UKMET IS A TAD
SLOWER AND DEEPER THAN THE LATEST MODEL CONSENSUS. 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 SECOND CLOSEST TO THE PREFERENCE.


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.


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.


...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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