Prognostic Meteorological Discussion
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000
FXUS10 KWNH 230722
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
321 AM EDT TUE AUG 23 2016

VALID AUG 23/0000 UTC THRU AUG 26/1200 UTC

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

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

MID-LEVEL TROF MOVING OUT OF THE CANADIAN ROCKIES TONIGHT TOWARD
MINN/ONTARIO BORDER
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/ECMWF BLEND
CONFIDENCE: AVERAGE

AS HAS BEEN THE TREND...THE MODELS ARE TIGHTLY AGREED UPON THROUGH
MUCH OF THE EARLY PERIOD BUT INFLUENCE/INTERACTION WITH RETURN
FLOW SHORTWAVE EJECTING OUT OF THE CENTRAL PLAINS.  THE 00Z NCEP
MODELS AND THE 00Z ECMWF TENDED TO FOLLOW THE SOLUTIONS THEY
SHOWED IN THE 12Z CYCLE.  THE NAM BECAME WEAK/FAST AS THE SYSTEM
DEVOLVES LATE WEDNESDAY WHILE THE 00Z GFS REMAINED SLOWER LIKE IT
HAS SHOWN FOR SEVERAL RUNS NOW.  THE ECMWF IS STILL IN THE GFS
CAMP...ALTHOUGH IT WAS A TAD SLOWER THAN THE GFS AND A BIT WEAKER.
 THE UKMET WAS IN THE WEAK/FAST CAMP WHILE THE CANADIAN LOOKED TO
BE FAR TOO SHARP.  STILL THINK A GFS/ECMWF BLEND WILL WORK TO COME
UP WITH THE BEST COMPROMISE.

BROAD BASE OF THE TROF/SHORTWAVE CROSSING S CA/SOUTHWEST MON/TUES
AND CENTRAL ROCKIES AND CENTRAL PLAINS THURS.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: AVERAGE

THE WESTERN PORTION OF THE BROAD BASE OF THE SOUTHWEST UPPER LEVEL
TROF SHOWS BETTER AGREEMENT IN THE MODELS DURING ITS EVOLUTION
ACROSS THE FOUR CORNERS BY TUES EVENING.  THE 00Z NAM REMAINS
DEEPER/SOUTH AS THE WAVE SHEARS INTO CONFLUENT RETURN FLOW ACROSS
THE SOUTHERN ROCKIES LATE WED INTO THURS RATHER THAN DRAWING WAVE
ENERGY OUT.  THE 00Z GFS/ECMWF/UKMET/CMC WERE INCLINED TO DRAW OUT
THE VORTICITY AS WOULD BE EXPECTED IN A CONFLUENT FLOW REGIME.  SO
WILL KEEP THE PREVIOUSLY ISSUED PREFERENCE FOR A NON NAM BLEND.

SHORTWAVE CARVING OUT WESTERN SIDE OF WESTERN US POSITIVE TILT
TROF ACROSS THE NORTHERN US ROCKIES BY THURS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: AVERAGE TR

THE 00Z NCEP MODELS GENERALLY HAD GOOD RUN TO RUN CONSISTENCY WITH
THE FLOW OVER THE TOP OF THE PACIFIC RIDGE AND HOW THAT FLOW
EVENTUALLY MAKES ITS WAY  INTO THE NORTHERN U.S. ROCKIES.  THE
ECMWF KEPT PRETTY GOOD RUN TO RUN CONTINUITY THROUGH EARLY
THURSDAY...AT WHICH POINT IT OPTED FOR LOWERING HEIGHTS ACROSS THE
INTERMOUNTAIN WEST LIKE THE NAM.  WHILE THERE HAS BEEN A MOVE THIS
WAY...THE CMC SOLN LOOKS TO HAVE MUCH MORE CYCLONIC CURVATURE OVER
THE INTERMOUNTAIN REGION THAN OTHER MODELS.  AS A RESULT...WILL
CONTINUE TO FAVOR A NON CMC BLEND.

BANN

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

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

$$





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