Prognostic Meteorological Discussion
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FXUS10 KWNH 250642
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
241 AM EDT SAT MAR 25 2017

VALID MAR 25/0000 UTC THRU MAR 28/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...CLOSED LOW DIVING THROUGH EASTERN CANADA BY SAT MORNING...
...COLD FRONT ADVANCING DOWN ACROSS THE GREAT LAKES/NORTHEAST...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF
CONFIDENCE: ABOVE AVERAGE

THERE ARE ONLY MINOR DIFFERENCES ASSOCIATED WITH THE HEIGHT FALLS
PUSHING THROUGH EASTERN CANADA. REGARDING THE COLD FRONT SAGGING
DOWN ACROSS THE NORTHEAST AND INTO THE MID-ATLANTIC REGION...THE
00Z NAM DRIVES THE COLD FRONT THE FARTHEST SOUTH...WITH THE 00Z
UKMET HANGING THE FRONT UP FARTHEST NORTH. THE 00Z GFS/00Z ECMWF
AND 00Z CMC SPLIT THE DIFFERENCE IN THE MIDDLE. DIFFERENCES
OVERALL ARE NOT THAT SIGNIFICANT...BUT WILL LEAN TOWARD A BLEND OF
THE 00Z GFS AND 00Z ECMWF AT THIS TIME WITH THE FRONT. A GENERAL
MODEL COMPROMISE WILL OTHERWISE BE FINE WITH THE CLOSED LOW
EVOLUTION.


...CLOSED LOW EVOLUTION OVER THE CENTRAL PLAINS FRI...
...ENERGY CROSSING THE MID MS/OH VALLEYS THROUGH SAT...
...SYSTEM WEAKENING INTO THE GREAT LAKES/NORTHEAST BY SUN/MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE LATEST GUIDANCE TAKES THE CLOSED LOW/UPPER TROUGH APPROACHING
THE LOWER/MID MS VALLEY OFF TO THE NORTHEAST OVER THE NEXT COUPLE
OF DAYS...WITH THE SYSTEM GRADUALLY WEAKENING AS IT CROSSES THE OH
VALLEY AND LIFTS INTO THE GREAT LAKES REGION. BY LATER MON AND
TUES THE SYSTEM WILL BE ENTERING CONFLUENT FLOW ALOFT AS IT MOVES
INTO THE NORTHEAST AND WILL BE GRADUALLY DAMPENING OUT. THE 00Z
UKMET IS A TAD SLOWER THAN THE MODEL CONSENSUS WITH THE EJECTING
TROUGH AS IT APPROACHES THE GREAT LAKES REGION...AND ITS SURFACE
LOW IS A LITTLE SLOWER AND LEFT OF THE SAME CONSENSUS. GIVEN THE
STRONG MODEL AGREEMENT SEEN OTHERWISE...WILL PREFER A NON-UKMET
CONSENSUS.


...WEAKENING TROUGH/COLD FRONT OVER THE NORTHERN PLAINS ON SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

ONLY VERY MINOR DIFFERENCES NOTED WITH THIS SYSTEM ARE NOTED...SO
A GENERAL MODEL COMPROMISE WILL BE PREFERRED.


...NORTHERN STREAM TROUGH CROSSING THE PACIFIC NORTHWEST ON SAT...
...EJECTING ACROSS THE NORTHERN PLAINS/UPPER MIDWEST SUN/MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PREFERENCE: NON-GFS CONSENSUS...WEIGHTED TOWARD THE 00Z ECMWF
CONFIDENCE: AVERAGE

THE MODELS ADVERTISE THE NORTHERN STREAM COMPONENT OF A LARGER
SCALE WESTERN U.S. TROUGH CROSSING THE PACIFIC NORTHWEST ON SUN
WITH THE ENERGY THEN PROGRESSIVELY ADVANCING EASTWARD ACROSS THE
NORTHERN PLAINS AND UPPER MIDWEST SUN AND MON. THE 00Z GFS TENDS
TO HANG ON TO A STRONGER AND GRADUALLY SLOWER UPPER TROUGH VERSUS
THE MODEL CONSENSUS. THE REMAINING MODELS ARE MORE PROGRESSIVE AND
A BIT FLATTER...BUT THE 00Z NAM AND 00Z UKMET BY THE END OF THE
PERIOD ARE THE FASTEST...WITH THE 00Z CMC/00Z ECMWF SOLUTIONS A
LITTLE SLOWER. WILL PREFER A NON-GFS CONSENSUS AT THIS
POINT...WITH SOMEWHAT STRONGER WEIGHTING TOWARD THE ECMWF WHICH IS
PRETTY CLOSE TO THE OVERALL MODEL CONSENSUS.


...SOUTHERN STREAM UPPER TROUGH OVER THE WEST ON SAT...
...ENERGY EJECTING INTO THE CNTRL/SRN PLAINS SUN NIGHT/MON...
...SYSTEM WEAKENING INTO THE OH VALLEY MON NIGHT/TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 48 HOURS
            00Z ECMWF...AFTER 48 HOURS
CONFIDENCE: AVERAGE

THE MODELS ARE IN RATHER STRONG AGREEMENT THROUGH ABOUT 48 HOURS
WITH THE EVOLUTION OF THE SOUTHERN STREAM TROUGH/ENERGY CROSSING
THE SOUTHWEST/FOUR CORNERS REGION AND EJECTING OUT INTO THE
CENTRAL/SOUTHERN PLAINS REGION. THEREAFTER...THE 00Z GFS BECOMES
AN OUTLIER IN BECOMING TOO WEAK AND PROGRESSIVE WITH THE HEIGHT
FALL EVOLUTION AND ALSO WITH ITS ATTENDANT WAVE OF LOW PRESSURE
WHICH IT HAS QUICKLY LIFTING UP ACROSS THE OH VALLEY BY LATER
MON/TUES. THE 00Z NAM FOR ITS PART APPEARS TO BE A TAD TOO DEEP
WITH THE ENERGY AS IT ADVANCES EAST OF THE PLAINS AND INTO THE
LOWER MS/TN VALLEYS. THE 00Z CMC IS ONLY A TAD WEAKER THAN THE
NAM. THE 00Z UKMET AND 00Z ECMWF ARE A BIT WEAKER THAN THE NAM/CMC
SOLUTIONS BY COMPARISON BUT NOT AS WEAK AS THE GFS. WILL PREFER A
GENERAL MODEL COMPROMISE THROUGH 48 HOURS...AND THEN LEAN TOWARD
THE ECMWF THEREAFTER SINCE IT IS VERY CLOSE TO THE MODEL CONSENSUS
AND ALSO SHOWS RATHER GOOD CONTINUITY.


...UPPER TROUGH/COLD FRONT REACHING THE WEST COAST SUN...
...CLOSED LOW EVOLUTION INTO THE SOUTHWEST MON/TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 48 HOURS
            00Z UKMET/00Z CMC/00Z ECMWF BLEND...AFTER 48 HOURS
CONFIDENCE: AVERAGE

THE MODELS TAKE ANOTHER UPPER TROUGH AND ASSOCIATED COLD FRONT
ACROSS THE WEST COAST ON SUN...WITH SPLIT FLOW THEN ALLOWING THE
BULK OF THE ENERGY TO DIG SOUTHEAST INTO THE SOUTHWEST AND FOUR
CORNERS REGION THROUGH MON AND TUES. THE 00Z GFS GRADUALLY BECOMES
SLOWER THAN THE MODEL CONSENSUS WITH THE CLOSED LOW EVOLUTION. THE
00Z NAM ALSO IS A BIT DEEPER THAN ANY OTHER MODEL BY THE END OF
THE PERIOD. THE 00Z UKMET/00Z CMC AND 00Z ECMWF ARE WELL CLUSTERED
AFTER 48 HOURS AND ARE CLOSEST TO THE MODEL CONSENSUS. A GENERAL
MODEL COMPROMISE SHOULD BE FINE THROUGH ABOUT 48 HOURS...WITH A
UKMET/CMC/ECMWF BLEND PREFERRED THEREAFTER.

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

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

ORRISON

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