Prognostic Meteorological Discussion
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FXUS10 KWNH 240447
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 AM EDT FRI MAR 24 2017

VALID MAR 24/0000 UTC THRU MAR 27/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS

...CLOSED LOW DIVING THROUGH EASTERN CANADA BY SAT MORNING...
...COLD FRONT ADVANCING DOWN ACROSS THE GREAT LAKES/NORTHEAST...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

DIFFERENCES AT THIS POINT ARE RATHER MODEST WITH THE EVOLUTION OF
THE STRONG UPPER LOW MOVING INTO EASTERN CANADA AND THE COLD FRONT
SWEEPING SOUTHEAST ACROSS THE GREAT LAKES AND NORTHEAST. A GENERAL
MODEL COMPROMISE WILL BE PREFERRED AT THIS TIME.


...CLOSED LOW EVOLUTION OVER THE CENTRAL PLAINS FRI...
...ENERGY CROSSING THE MID MS/OH VALLEYS THROUGH SAT...
...SYSTEM WEAKENING INTO THE GREAT LAKES BY SUN/MON...

PREFERENCE: BLEND OF THE 00Z NAM/00Z GFS AND 12Z UKMET
CONFIDENCE: AVERAGE

THE MODELS SHOW PRETTY GOOD AGREEMENT WITH THEIR MASS FIELDS
THROUGH ABOUT 48 HOURS...WITH THE 12Z ECMWF TENDING TO BE A LITTLE
SLOWER THAN THE MODEL CONSENSUS THEREAFTER AS THE ENERGY LIFTS OUT
OF THE MID MS/OH VALLEYS AND TOWARD THE GREAT LAKES REGION. THE
12Z CMC ALSO GRADUALLY LIFTS THE SYSTEM NORTH A BIT FASTER THAN
THE MODEL CONSENSUS FROM ABOUT 60 HOURS ONWARD. STRONGER MODEL
CLUSTERING OVERALL IS MORE ALIGNED WITH THE 00Z NAM/GFS AND 12Z
UKMET...AND SO A BLEND OF THESE SOLUTIONS WILL BE PREFERRED.


...NORTHERN STREAM TROUGH/COLD FRONT CROSSING THE NORTHWEST
THROUGH FRI...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THERE ARE ONLY MINOR TIMING DIFFERENCES WITH THIS SYSTEM AND ITS
ASSOCIATED COLD FRONT...THUS A GENERAL MODEL COMPROMISE IS
PREFERRED TO SMOOTH OUT THESE SMALLER SCALE DIFFERENCES.


...SOUTHERN STREAM COMPONENT OF UPPER LEVEL TROUGH OVER THE WEST
ON SAT...
...ENERGY EJECTING INTO THE CENTRAL/SOUTHERN PLAINS SUN
NIGHT/MON...

PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 60 HOURS
            NON-GFS CONSENSUS...AFTER 60 HOURS
CONFIDENCE: AVERAGE

THE MODELS CLUSTER TOGETHER VERY WELL WITH THE TIMING AND DEPTH OF
THE SOUTHERN STREAM TROUGH CROSSING CA AND THE GREAT BASIN FRI AND
SAT. THEREAFTER...THE 00Z GFS BEGINS TO TREND A BIT STRONGER THAN
THE MODEL CONSENSUS AT THE SURFACE AND ALOFT...AND ESPECIALLY BY
SUN NIGHT/MON AS THE SYSTEM CROSSES OUT THROUGH THE
CENTRAL/SOUTHERN PLAINS. THE LATEST GEFS MEAN AND ECENS MEAN TEND
TO FAVOR THE SLIGHTLY WEAKER CONSENSUS BY LATER SUN/MON. WILL
PREFER A GENERAL MODEL COMPROMISE THROUGH ABOUT 60 HOURS...AND A
NON-GFS CONSENSUS THEREAFTER.


...UPPER TROUGH/COLD FRONT REACHING THE WEST COAST SUN EVENING...

PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS BRING THE NEXT UPPER TROUGH AND ASSOCIATED COLD FRONT
ACROSS THE WEST COAST BY SUN EVENING WITH THE TROUGH THEN MOVING
INLAND ON MON. THE 00Z NAM AND 12Z ECMWF ARE A TAD FASTER WITH THE
FRONT VERSUS THE 00Z GFS/12Z CMC AND 12Z UKMET AS IT APPROACHES
AND ARRIVES ALONG THE WEST COAST.  BY LATER SUN AND MON...WITH
RESPECT TO THE UPPER TROUGH...THE 00Z NAM APPEARS TO BE A TAD TOO
FAST...WITH PERHAPS THE 12Z ECMWF EDGING A LITTLE TOO SLOW. WILL
COMPROMISE BY SUGGESTING A BLEND OF THE 00Z GFS AND 12Z ECMWF AT
THIS POINT.

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

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

ORRISON

$$





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