Prognostic Meteorological Discussion
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FXUS10 KWNH 231654
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MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1253 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 00Z 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 AND 12Z GFS ARE A LITTLE FASTER THAN THE NON-NCEP
GUIDANCE...WITH THE 00Z UKMET AND 00Z ECMWF A LITTLE SLOWER. THE
00Z CMC IS OVERALL THE SLOWEST SOLUTION AND IS AN OUTLIER. CINDY
HAS BEEN ACCELERATING OVER THE LAST SEVERAL HOURS AND IS BEGINNING
TO OUTRUN 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: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF
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 AND 00Z CMC
ARE OVERALL TENDING TO BE A BIT DEEPER WITH THE LONGWAVE TROUGH BY
THE END OF THE PERIOD. WILL PREFER THE SLIGHTLY LESS AGGRESSIVE
12Z GFS/00Z UKMET AND 00Z ECMWF AT THIS TIME AS A CONSENSUS.


...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 00Z CMC IS A
BIT OF A SLOW OUTLIER...WITH THE REMAINING GUIDANCE 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: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: 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...THE 12Z NAM STILL HINTS THAT IT MAY BE STRONG ENOUGH TO
STILL ARRIVE AS A WEAK UPPER LOW. THE 00Z CMC IS THE
WEAKEST/FLATTEST BY MON AS THE ENERGY ARRIVES...WITH THE 12Z
GFS/00Z UKMET AND 00Z ECMWF ALL SPLITTING THE DIFFERENCE IN
BETWEEN CAMPS. THE BETTER TIMING/DEPTH AGREEMENT GENERALLY LIES
WITH THE GFS AND ECMWF...SO A BLEND OF THESE TWO SOLUTIONS WILL BE
PREFERRED FOR NOW.


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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