Prognostic Meteorological Discussion
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086
FXUS10 KWNH 240440
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1240 AM EDT TUE MAY 24 2016

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

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

00Z MODEL EVALUATION INCLUDING PREFERENCE AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

CLOSED LOW LIFTING FROM MID-ATLANTIC TO THE NORTHEAST MON-WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM/GFS CONTINUE THE TREND OF MODEL AND ENSEMBLE MEAN
TIGHT FAIRLY TIGHT CLUSTERING THROUGH WED AS THE WAVE IS ABSORBED
INTO THE MEAN FLOW.  AS SUCH CONFIDENCE IS ABOVE AVERAGE FOR AN
OPERATIONAL MODEL BLEND.


SHORTWAVE MOVING OVER THE TOP OF THE MEAN RIDGE IN SOUTHEASTERN
CANADA...
SURFACE LOW DEVELOPING OVER SOUTHERN QUE...COLD FRONT DROPPING
SOUTH INTO
THE NORTHEASTERN U.S. ON WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS AND 12Z ECMWF/CMC BLEND
CONFIDENCE: AVERAGE

THERE IS FAIRLY GOOD TIMING WITH THE WAVE OVERALL BUT THERE
REMAINS SOME SPREAD IN THE AMPLIFICATION OF THE WAVE.  THE 00Z NAM
IS MUCH STRONGER AND CAN BE DEPICTED BEST IN THE 7H HEIGHT FIELD
FOLLOWED BY THE 12Z UKMET...BOTH EVENTUALLY BECOMING SLOW
OUTLIERS.  THE 12Z CMC IS GENERALLY FLAT OVERALL BUT THIS DOES NOT
APPEAR TO NEGATIVELY AFFECT THE OVERALL SHAPE/TIMING OF THE FRONT
AND OTHER SENSIBLE FIELDS.  BOTH GFS/ECMWF KEEP WITH THEIR
CONTINUITY AND ARE SUPPORTED BY THEIR ENSEMBLE SUITE; GFS A BIT
FAST WED INTO THURS COMPARED TO THE ECMWF... BUT OVERALL WILL
SUPPORT A 00Z GFS AND 12Z ECMWF/CMC BLEND AT AVERAGE CONFIDENCE.


QUASI-STATIONARY CLOSED UPPER LOW EAST OF THE SOUTHERN CANADIAN
ROCKIES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: AVERAGE

STRONG AGREEMENT EXISTS WITHIN THE MODEL SUITE UP UNTIL ABOUT
MIDDAY WED WHEN THE SHORTWAVE MOVING OUT OF THE SOUTHWEST FLOW
BEGINS TO INFLUENCE THE UPPER LOW...  THE 12Z UKMET IS FIRST TO
SHIFT EAST BUT IS GENERALLY WEAKER THAN THE 00Z NAM WHICH IS QUITE
STRONG WITH THE APPROACHING S/W TO INFLUENCE THE REMAINING UPPER
LOW MORE THAN MUCH OF THE GUIDANCE.  THE 12Z ECMWF RESOLVED A BIT
STRONGER/CONSOLIDATED THAN PRIOR RUNS AND SHIFTED TOWARD THE WEST
TOWARD THE RECENT GFS CAMP.  THE 00Z GFS DID NOT CHANGE MUCH
THOUGH IS A BIT MORE AMPLIFIED AND FURTHER EAST...CLOSER TO THE
ECMWF.  AS SUCH CONFIDENCE IS A BIT BETTER OVERALL IN AN 00Z/12Z
ECMWF BLEND.


UPPER LEVEL SHORTWAVE/DEVELOPING SURFACE WAVE LIFTING FROM THE
CENTRAL PLAINS
TO THE UPPER MIDWEST WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS AND 12Z ECMWF/CMC BLEND
CONFIDENCE: AVERAGE

MODELS APPEAR TO CONTINUE TO CONSOLIDATE ON A SOLUTION AS TIMING
APPEARS TO BE CONVERGING A BIT MORE...THOUGH 12Z SPAGHETTI PLOTS
CONTINUE TO SHOW A LARGE AMOUNT OF SPREAD.  THIS SEEMS MAINLY
RELATED TO HOW FAR EAST/WEST THE TRACK OF THE WAVE IS AS IT
AMPLIFIES OUT OF THE ROCKIES INTO THE DAKOTAS/MN BY WED NIGHT.

THE 12Z UKMET IS MOST OUT OF PHASE WITH THE REST OF THE SUITE AS
IT CONTINUES TO EVOLVED IN FRACTURED/SMALLER VORTICITY ELEMENTS
THAN A LARGER WAVE.  THE 00Z NAM IS QUITE RESOLUTE IN QUICKLY
DEVELOPING A STRONG AND SLIGHTLY FASTER SOLUTION COMPARED TO THE
REST OF THE GUIDANCE...AND THEREFORE IS A BIT SUSPECT.   THE 00Z
GFS HAS TRENDED A BIT STRONGER WITH THE WAVE BUT IS ALSO THE
FARTHEST WEST SOLUTION...AND GIVEN PROXIMITY TO THE LINGERING
QUASI-STATIONARY UL IN MT IS VERY SLOW TO PULL NE INTO CANADA.
THE GFS SOLUTION APPEARS QUITE REASONABLE COMPARED TO THE MOST
CENTRAL ECMWF.  THE 12Z CMC SHOWS THE OTHER SIDE OF THE PREFERRED
SPECTRUM ON THE EASTERN SIDE WITH SIMILAR AMPLIFICATION TO THE
GFS/ECMWF BUT GIVEN THE PROXIMITY TO THE UL
IS QUICKER TO SHED TOWARD THE NORTHEAST INTO CANADA.   ALL
CONSIDERED WILL PREFER A 00Z GFS AND 12Z ECMWF/CMC BLEND TO BEST
REPRESENT THE SPECTRUM OF BEST POSSIBILITIES AND SPREAD IS
RESULTANT TO THE PROXIMITY TO THE UL...SO CONFIDENCE IS ONLY
MODERATE (AVERAGE) GIVEN THE SPACING REMAINS MODERATE.


TROUGH AMPLIFYING INTO CLOSED UPPER-LEVEL LOW OFF THE CA COAST BY
TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE LATEST MODELS AND MEANS ARE FAIRLY WELL CLUSTERED AS THE BASE
OF TROF SWINGS THROUGH THE SOUTHWEST WED/THURS WITH ONLY THE 00Z
NAM LAGGING EVER SO SLOWLY (WHICH IT IS APT TO DO).  LARGER SPREAD
BEGINS TO MANIFEST AS THE WAVE LIFTS/EJECTS INTO THE CENTRAL
PLAINS BY FRIDAY.  THE 12Z UKMET IS FAST AND STRONG WITH THIS
EJECTION...MAKING IT LESS FAVORABLE.  THE REST OF THE SUITE
MATCHES WELL TO THE ENSEMBLE SUITE AND SURFACE LOW
CLUSTER....THOUGH THE 12Z ECMWF AND ECENS MEAN ARE GENERALLY
WEAKER AND THEREFORE TRACK THE SURFACE LOW DUE EAST ALONG THE
KS/OK BOARDER AND ARE GENERALLY WELL CLUSTERED TO THIS SOLUTION
WHILE GEFS/CMCE MEMBERS ALONG WITH THE 00Z NAM/GFS ARE A BIT
STRONGER AND HOOK NEWARD IN W KS.  AT THIS TIME IT IS DIFFICULT TO
DETERMINE EXACT STRENGTH AT EJECTION TIME AND MAY FAVOR THE
GFS/CMC SOLUTIONS VERSUS ECMWF GIVEN CONTINUITY BUT IT IS NOT THAT
GREAT AT THIS TIME TO DIFFERENTIATE... AS SUCH WILL SUPPORT A
NON-UKMET BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE GIVEN THE
OVERALL TIMING/PLACEMENT IS STRONG UNTIL THE VERY END.


CLOSED UPPER LOW DESCENDING INTO PACIFIC NORTHWEST THURS/FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET/CMC AND 18Z GEFS BLEND
CONFIDENCE: AVERAGE

RUN TO RUN ENSEMBLE TRENDS HAVE BEEN TRENDING SLOWER WITH THE
UPPER LEVEL CLOSED LOW ENTERING THE PACIFIC NORTHWEST THURSDAY
INTO FRIDAY.  ENSEMBLE MEANS (18Z GEFS/12Z ECENS/CMCE) ARE
GENERALLY WELL AGREED UPON.  THE 00Z NAM AND GFS ARE BOTH
FASTER...WITH THE NAM HAVING A LESS ORGANIZED/CONSOLIDATED
INTERNAL CORE WHICH IS AWAY FROM MUCH OF THE REST OF THE GUIDANCE.
 THE 00Z GFS ON THE OTHER HAND IS CONSOLIDATED BUT ALSO BROKE FROM
THE TREND AND SHIFTED FASTER WITH THIS RUN.  AS SUCH WILL FAVOR
THE 12Z ECWMF/CMC AND UKMET WHICH MATCH THE ENSEMBLES A BIT
BETTER.  CONFIDENCE IS ONLY AVERAGE GIVEN THE SPREAD IS MILD.

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

GALLINA

$$





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