Prognostic Meteorological Discussion
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FXUS10 KWNH 231845
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 PM EDT FRI JUN 23 2017

VALID JUN 23/1200 UTC THRU JUN 27/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...T.D. CINDY CROSSING THE TN VALLEY...
...TRANSITIONING TO A POST-TROPICAL/EXTRATROPICAL LOW...
...COLD FRONT THROUGH THE EASTERN U.S...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

THE MODELS ARE IN GOOD AGREEMENT IN ALLOWING CINDY TO CROSS THE TN
VALLEY/CENTRAL APPALACHIANS AND CENTRAL MID-ATLANTIC REGION OVER
THE NEXT 24 HOURS WHILE GRADUALLY MERGING WITH A FRONT MOVING
ACROSS THE EASTERN UNITED STATES. THIS WILL ALLOW CINDY TO
TRANSITION FROM A TROPICAL DEPRESSION TO A
POST-TROPICAL/EXTRATROPICAL LOW CENTER BY THIS EVENING. THE SYSTEM
WILL EXIT NORTHEAST AND OFFSHORE SOUTHERN NEW ENGLAND BY MIDDAY
SAT. THE 12Z NAM/12Z GFS AND 12Z ECMWF ARE CLUSTERED A LITTLE
FASTER THAN THE 12Z UKMET AND 12Z CMC. CINDY CONTINUES TO
ACCELERATE AND IS OUTRUNNING THE MODEL CONSENSUS A LITTLE. SO THE
PREFERENCE AT THIS POINT WILL BE TO LEAN TOWARD THE MORE
PROGRESSIVE END OF THE GUIDANCE. WILL SUGGEST A NAM/GFS/ECMWF
BLEND AT THIS POINT FOR THE MASS FIELDS. LOCALLY VERY HEAVY
RAINFALL WILL BE ASSOCIATED WITH CINDY...PLEASE CONSULT THE LATEST
QPFPFD AND QPFERD FOR DETAILS ON THE EXPECTED RAINFALL/FLASH
FLOODING POTENTIAL.


...LONGWAVE TROUGH DIGGING ACROSS THE CENTRAL/EASTERN U.S....
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

MULTIPLE SHORTWAVE IMPULSES MOVING ACROSS THE MIDWEST AND TOWARD
THE EASTERN U.S. WILL DRIVE THE AFOREMENTIONED COLD FRONT THROUGH
THE EASTERN U.S. OVER THE NEXT DAY OR SO...BUT WILL ALSO LEAD THE
WAY FOR A LONGWAVE TROUGH TO AMPLIFY AND DIG EAST ACROSS THE
CENTRAL/EASTERN U.S. THROUGH THE WEEKEND. THE 12Z NAM TENDS TO BE
A BIT DEEPER WITH THE LONGWAVE TROUGH BY THE END OF THE PERIOD.
WILL PREFER THE SLIGHTLY LESS AGGRESSIVE GLOBAL MODEL
CONSENSUS...AND SUPPORT A NON-NAM CONSENSUS AT THIS POINT.


...UPPER LOW MOVING INTO BRITISH COLUMBIA BY MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC CONSENSUS
CONFIDENCE: ABOVE AVERAGE

ALL OF THE MODELS INDICATE AN UPPER LOW EXITING THE GULF OF AK AND
MOVING INTO BRITISH COLUMBIA BY MON WITH A SOUTHWARD EXTENSION OF
A TROUGH AXIS IMPACTING THE PACIFIC NORTHWEST. THE 12Z CMC IS
STILL A LITTLE SLOW WITH THIS SYSTEM COMPARED TO THE REMAINING
GUIDANCE WHICH IS WELL CLUSTERED ON TIMING AND DEPTH. WILL PREFER
A NON-CMC CONSENSUS AS A RESULT.


...DAMPENING UPPER LOW APPROACHING NORTHERN CA/OR BY MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC CONSENSUS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE GUIDANCE BRINGS AN UPPER LOW NORTH OUT OF THE SUBTROPICS THIS
WEEKEND OFFSHORE THE WEST COAST AND THEN ADVANCES IT NORTHEAST IN
A RAPIDLY WEAKENING FASHION TOWARD NORTHERN CA/OR BY MON. WHILE
MOST OF THE GUIDANCE BRINGS THE SYSTEM INLAND AS AN OPEN WAVE
AXIS...THERE IS SOME POTENTIAL FOR IT TO COME IN STILL AS A WEAK
UPPER LOW. OVERALL THE 12Z CMC IS THE WEAKEST AT THIS POINT. BASED
ON THE LATEST CLUSTERING OF SOLUTIONS...A NON-CMC CONSENSUS WILL
BE PREFERRED.


WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/

ORRISON

$$





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