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109
FXUS10 KWNH 230506
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
105 AM EDT SUN JUL 23 2017

VALID JUL 23/0000 UTC THRU JUL 26/1200 UTC

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

00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


...SYSTEM APPROACHING THE PACIFIC NORTHWEST LATE TUESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 12Z CANADIAN IS MUCH QUICKER TO TAKE THE MID-LEVEL CLOSED LOW
EASTWARD INTO BRITISH COLUMBIA ON MONDAY INTO TUESDAY...WHILE THE
REMAINING DETERMINISTIC GUIDANCE IS SLOWER. WHILE THE REMAINING
DETERMINISTIC MODELS SHOW MINOIR DIFFERENCES...ENSEMBLE SPREAD HAS
DRAMATICALLY SHRUNK COMPARED TO YESTERDAY AND AGREES WITH THE NON
12Z CMC BLEND OF GUIDANCE.


...SYSTEM MOVING THROUGH SOUTH-CENTRAL CANADA MONDAY/TUESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z UKMET BLEND
CONFIDENCE: AVERAGE

THE 12Z UKMET IS ON THE FASTER SIDE OF THE MODELS WITH A SHORTWAVE
AND ASSOCIATED COLD FRONT SWEEPING ACROSS THE NORTHERN TIER OF THE
U.S. THROUGH WED. BETTER DETERMINISTIC/ENSEMBLE SUPPORT EXISTS FOR
A NON 12Z UKMET BLEND WITH THIS SYSTEM. ENSEMBLE TRENDS HAVE ALSO
BEEN SLOWER SINCE YESTERDAY.


...UPPER LOW NEAR CALIFORNIA SUNDAY-TUESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

ONLY MINOR DIFFERENCES EXIST WITH THIS SYSTEM SO A GENERAL MODEL
BLEND IS PREFERRED TO SMOOTH OUT SMALLER SCALE DIFFERENCES.


...SHORTWAVE MOVING ACROSS THE GREAT LAKES SUN/NORTHEAST MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/00Z NAM BLEND
CONFIDENCE: AVERAGE

THE 00Z GFS SURFACE LOW DEPICTION TO MOVE OFF OF THE MID-ATLANTIC
COAST MONDAY IS WEAKER THAN THE REMAINING DETERMINISTIC CONSENSUS
AND DISPLACED TO THE SOUTH. THE ENSEMBLE SCATTER LOW PLOTS HAVE
SHOWN GROWING AGREEMENT WITH EACH CYCLE AND CURRENTLY RESIDE
CLOSEST TO THE 00Z NAM AND 12Z ECMWF. THE 12Z UKMET IS FASTER THAN
A MAJORITY OF GUIDANCE. THIS WAS LIKELY THE BIGGEST DIFFERENCE
NOTED WITH THE MASS FIELDS OF THIS SYSTEM.


www.wpc.ncep.noaa.gov/html/model2.shtml
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

OTTO

$$





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