Prognostic Meteorological Discussion
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000
FXUS10 KWNH 200645
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
144 AM EST FRI JAN 20 2017

VALID JAN 20/0000 UTC THRU JAN 23/1200 UTC

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

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

CLOSED UPPER LOW OVER CNTRL/SRN HIGH PLAINS TRACKING TO UPPER MS
VALLEY/GREAT LAKES FRI WITH
ASSOCIATED SURFACE WAVE INTO THE OHIO VALLEY FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

00Z GFS/NAM CONTINUE TO BE IN STRONG ALIGNMENT IN TIMING PLACEMENT
AND STRENGTH OF THE WAVE AS IT SHEARS ACROSS THE UPPER MS
VALLEY/GREAT LAKES AND NORTHWEST ATLANTIC/NEW ENGLAND THROUGH SAT.
 AS THE NORTHWEST PORTION OF THE WAVE RETROGRADES THERE IS A BIT
OF BINARY INTERACTION WITH THE UPSTREAM (SOUTH) WAVE...BUT EVEN
THIS INTERACTION IS MUCH BETTER HANDLED.  AS SUCH A GENERAL MODEL
BLEND IS PREFERRED AT ABOVE AVERAGE CONFIDENCE.

07Z UPDATE: LITTLE CHANGES WITH 00Z NON-NCEP SOLUTIONS PROVIDE
FURTHER AGREEMENT/CONFIDENCE IN A GENERAL MODEL BLEND.


LONG WAVE/KICKER UPPER TROUGH DIGGING INTO THE SOUTHWEST US
TONIGHT/FRIDAY
DEVELOPING/CLOSING MID LEVEL LOW OVER THE CENTRAL PLAINS BY EARLY
SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

SHORTWAVE CURRENTLY TRACKING ACROSS N AZ PER GOES WV MOSAIC WILL
CONTINUE ON AN ENE TRACK INTO THE HIGH PLAINS FRIDAY NIGHT.  THE
WAVE WILL BEGIN TO LIFT NORTHEAST WITH AN ASSOCIATED SURFACE WAVE
WITH A NORTH OR NORTHWEST EXTENDING SURFACE TROF UNDER THE
INFLUENCE OF THE LARGER SCALE BROAD CYCLONIC FLOW OVER THE
ROCKIES/NORTHERN PLAINS.  THE EXACT DETAILS MAY NOT BE PERFECTLY
ALIGNED BUT THE OVERALL PLACEMENT/PATTERN AND SHAPE ARE BECOMING
MUCH BETTER AGREED UPON.  BY LATE SATURDAY INCREASED INTERACTION
WITH THE REMAINING SHORTWAVE ENERGY ACROSS THE DAKOTAS WITH THE
PRECEDING WAVE LEADS TO SOME MINOR INCREASED SPREAD BUT OVERALL A
GENERAL MODEL BLEND SEEMS TO HANDLE THE LARGER SCALE DETAILS WITH
GOOD AGREEMENT ENOUGH SO THAT CONFIDENCE IS ABOVE AVERAGE IN THIS
GENERAL BLEND.

07Z UPDATE: LITTLE CHANGES WITH THE 00Z NON-NCEP SOLUTIONS PROVIDE
FURTHER AGREEMENT/CONFIDENCE IN A GENERAL MODEL BLEND.


SECONDARY HEIGHT FALLS ACROSS THE WEST LATE FRIDAY/SATURDAY WHILE
BASE ROLLS THROUGH THE SOUTHWEST INTO THE SOUTHERN PLAINS BY SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: AVERAGE

THE NEXT WAVE IS ALREADY ON THE DOORSTEP OF THE WEST COAST AS THE
EASTERN EXTENSION IS LEADING TO BROAD CONVECTIVE DEVELOPMENT
NEARING THE OR/CA COAST.  A BROAD STRONG SUPER-GEOSTROPHIC JET
BECOMES BROADLY DIFFLUENT ALONG THE WEST COAST ATTM.  THE MODELS
HANDLE THE RESULTANT DEEP CYCLONE NORTH OF THE JET FAIRLY WELL
WITH STRONG/TIGHT PACKING NOTED THROUGH AS IT WOBBLES JUST OFF THE
WA/OR COAST SAT INTO SUNDAY BEFORE FILLING AND MOVING NORTH.

THE GREATER MODEL SPREAD EXISTS WITH THE LEAD SHORTWAVE ENERGY
MOVING IN TANDEM WITH THE STRONG JET ACROSS THE SOUTHWEST SAT
BEFORE EJECTING INTO THE SOUTH TX.   IN THE BROADLY DIFFLUENT FLOW
AT THE SE EXTENT OF THE GLOBAL TROF...THE SHORTWAVE BEGINS TO WIND
UP ACROSS THE ARKLATEX SUNDAY...WITH A PRECURSORY SHORTWAVE
ROLLING THROUGH THE SOUTHEAST.  THIS LEADS TO A COMPLEX LOW LEVEL
SURFACE AND MOISTURE PATTERN COMPOUNDING DIFFERENCES IN QPF
(PLEASE REFER TO QPFPFD FOR ADDITIONAL DETAILS.  THE 00Z GFS
CONTINUES TO BE A BIT SLOWER THAN THE BULK OF THE ENSEMBLE AND
DETERMINISTIC SUITE; THOUGH IT AS BEEN NICELY TIMED WITH THE
ECMWF/UKMET AND CMC.  THE 12Z UKMET LIKE THE GFS IS MORE
CONCENTRIC AND WOUND UP THAN THE 12Z ECMWF/CMC WHICH SHOW A BIT
MORE OPENNESS TO THE WAVE AS A WHOLE BEFORE EVENTUALLY CLOSING
ACROSS THE SOUTHEAST INTO MONDAY.   THE 00Z NAM CONTINUES TO BE
MOST OUT OF PHASE INDICATING A MUCH BROADER AND OPEN WAVE BEFORE
CLOSING MUCH LATER AND FURTHER NORTH THAN THE REST OF THE
GUIDANCE.

INTERNAL VORTICITY LOBES LEAD TO TIMING/PLACEMENT DIFFERENCES WITH
THE SURFACE REFLECTIONS AS THEY ROTATE AROUND THE UPPER LOW
CENTROID...THIS WAS PARTICULARLY NOTED WITH THE 12Z EC WHICH
PRESENTS A FASTER SOLUTION TO THE OVERALL UPPER LOW WHILE THE 00Z
GFS WAS A BIT DELAYED.  A NON-NAM BLEND IS PRESENTED AS WPC
PREFERENCE THOUGH GIVEN MODERATE INTERNAL DIFFERENCES IN THESE
VORT LOBES...CONFIDENCE REMAINS AVERAGE EVEN THOUGH THE LARGER
PATTERN/TIMING/PLACEMENT IS QUITE GOOD.

07Z UPDATE: THE 12Z ECMWF CONTINUES TO BE SLIGHTLY FASTER THAN THE
SLOWER GFS AT THE END OF DAY 3 BUT HAS TRENDED BACK SLIGHTLY
CLOSER TO THE 00Z UKMET MAKING A BETTER OVERALL AGREEMENT WITH THE
GFS AND TIGHTENING THE NON-NAM BLEND.


APPROACH OF NEXT STRONG CLOSED LOW NEARING WEST COAST SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

YET ANOTHER STRONG SHORTWAVE APPROACHES THE WEST COAST BY LATE IN
THE PERIOD. MODELS CAN AGREE WITH PUMPING UP WEST COAST UPPER
RIDGING IN ADVANCE OF THIS FEATURE WITH RESULTANT AMPLIFICATION OF
THE UPPER TROUGH AS IT CROSSES EAST OF 150N BY SATURDAY AND
SATURDAY NIGHT.  THERE REMAINS SOME MINOR PLACEMENT DIFFERENCES
WITH THE INNER CORE OF THE UPPER LOW AS MATURES JUST NORTH OF THE
40N130W BENCHMARK LATE SUNDAY.  MOST OF SPREAD APPEARS TO BE
RELATED TO THE SIZE OF THE WOBBLE WITHIN THE LARGER GLOBAL TROF AS
A WHOLE. THE 12Z UKMET ENTERS THE WOBBLE SOUTH AND IS QUITE TIGHT
WITHIN THE ROTATION...KEEPING IT WELL SOUTHEAST OF THE ENSEMBLE
CENTROID OF SOLUTIONS.  THE 12Z CMC ENTERS SOUTH BUT MAKES A MUCH
ANTICYCLONIC WOBBLE PLACING IT NORTH OF THE ENSEMBLE CENTROID BY
THE END OF THE FORECAST PERIOD.  THE 00Z NAM ENTERS AT A SIMILAR
TACT TO THE LARGER TROF AS THE CMC/UKMET BUT JUST LIFTS TO THE OR
COAST AS A WEAKER SOLUTION WITHIN THE SPREAD.  THE 00Z GFS AND 12Z
ECMWF ARE QUITE AGREEABLE WITH A MODEST WOBBLE WHILE ALSO
REMAINING CENTRAL TO THE OVERALL SPREAD/LARGER SCALE TROF WITH
SIMILAR DEPTH STRENGTH.   THEY BOTH ALSO QUITE TIGHTLY REPRESENT
THE ENSEMBLE MEANS AS WELL AS SOME RUN TO RUN CONSISTENCY...ENOUGH
TO BE HIGHLY CONFIDENT AT SUCH A TIME IN THE FUTURE.   AS SUCH A
00Z GFS AND 12Z ECMWF BLEND IS WPC PREFERENCE AT SLIGHTLY ABOVE
AVERAGE CONFIDENCE.

07Z UPDATE: THE 00Z ECMWF TRENDED A BIT FURTHER SOUTH INITIALLY
AND SLIGHTLY WEAKER THAN THE 12Z RUN WHICH LEADS TO A LARGER
COUNTER-CLOCKWISE WOBBLE AND A BIT FURTHER DEPARTURE FROM THE
GFS/GEFS/ECENS MEAN BY THE END OF DAY 3.  THE UKMET IS SIMILAR TO
THE GFS WITH A TIGHTER WOBBLE BUT ALSO THE UKMET TRENDED FURTHER
NORTH INITIALLY AND LOOKS FAIRLY GOOD WITHIN THE OVERALL CLUSTER
AND IS MATCHED WELL WITH THE 00Z CMC.  AS SUCH A NON-NAM BLEND CAN
BE SUPPORTED WITH HIGHEST WEIGHTING TOWARD THE GFS/GEFS SOLUTIONS.

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

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

GALLINA

$$





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