Prognostic Meteorological Discussion
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000
FXUS10 KWNH 300410
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1209 AM EDT SAT JUL 30 2016

VALID JUL 30/0000 UTC THRU AUG 02/1200 UTC

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

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

MID-LEVEL TROF NEAR S LK MI LIFTS SLOWLY INTO NEW ENGLAND BY TUES
WITH WEAK SFC LOW OVER OHIO VALLEY REDEVELOPING ACROSS
MID-ATLANTIC ALONG COASTAL FRONTAL ZONE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND (MAINLY MID-ATLANTIC & SOUTH)
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

MODELS CONTINUE TO SHOW GOOD AGREEMENT IN EVOLUTION AND TIMING
THROUGH SUN EVENING AS THE 00Z NAM AND 12Z UKMET CONTINUE TO BE A
BIT STRONGER/MORE CONSOLIDATED ACROSS NEW ENGLAND BUT ONLY
SLIGHTLY SO.  THIS DOES NOT SEEM TO HAVE TOO MUCH
IMPACT/DIFFERENCES TO THE WEAK SURFACE WAVES ALONG THE COASTAL
FRONTAL ZONE FROM THE MID-ATLANTIC AND OFF THE LONG ISLAND/CAPE
COD COAST INTO THE NORTH ATLANTIC.  EXACT PLACEMENT OF THESE WAVES
CONTINUE TO HAVE GOOD AMOUNT OF SPREAD BUT GIVEN THE WEAK NATURE
OF THESE WAVES...RUN TO RUN VARIABILITY DUE TO CONVECTIVE IMPACT
MAY BE TOO DIFFICULT TO PRECISELY LOCK DOWN.

THE 12Z CMC DOES DEVIATE FROM THE CONSENSUS MAINLY MON/TUES AS AN
ANOMALOUSLY STRONG VORT CENTER LIKELY FROM CONVECTIVE FEEDBACK
ROLLS OUT OF THE OHIO VALLEY AND DEEPENS/ELONGATES THE TROF ACROSS
THE CAROLINAS.  THIS SEEMS UNLIKELY GIVEN ITS STRENGTH/SPEED
COMPARED TO THE REST OF THE GUIDANCE (INCLUDING PRIOR CMC RUNS).
THE IMPACT SEEMS TO AFFECT ONLY THE CAROLINAS/MID-ATLANTIC AND MAY
BE USEFUL ACROSS NEW ENGLAND TO FULLY DISMISS IT THERE.  STILL A
NON-CMC BLEND IS SUPPORTED WEIGHTED TOWARD THE ECMWF/GFS AT
SLIGHTLY ABOVE AVERAGE CONFIDENCE.


LEAD SHORTWAVE TROUGH CLOSING OFF WHILE CROSSING SW CANADA LATE
SAT COLD FRONT CROSSING MONTANA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/NAM AND 12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

IN CANADA/N TIER OF US...THE 00Z NAM IS WEAKER THAN YESTERDAY AT
THIS TIME...THOUGH STILL A BIT DEEPER THAN THE 12Z ECMWF/18Z GFS
WITH THE INNER CORE OF THE UPPER LOW TRACKING ACROSS THE CANADIAN
ROCKIES.  THE 12Z UKMET IS EVEN DEEPER...RESULTING IN A STRONGER
MORE OCCLUDED SURFACE LOW IN SASKATCHEWAN BY MONDAY EVENING/TUES
MORNING.  THE 00Z GFS KEEPS SOME CONTINUITY WITH PRIOR RUNS THOUGH
A BIT DEEPER NEARER TO THE 00Z NAM.  THE 12Z ECMWF/ECENS MEAN
SHIFTED TOWARD THE GFS TREND THROUGHOUT THE DEPTH OF THE
TROPOSPHERE PROVIDES SOLID CONFIDENCE.

FURTHER SOUTH IN THE LEE OF THE ROCKIES...THE ADVANCEMENT OF THE
NORTHERN CLOSED LOW HELPS TO DRAW/SHEAR SHORTWAVE ENERGY OUT OF
THE CENTRAL ROCKIES UPPER LEVEL RIDGE...SUPPORTING EASTWARD
PROGRESSION OF THE COLD FRONT BY MONDAY AS WELL AS SURFACE
CYCLOGENESIS INTO THE PLAINS BY TUESDAY.  SIMILAR TO FURTHER NORTH
THE 00Z NAM/12Z UKMET ARE QUITE STRONG/AMPLIFIED WITH THE SHEARED
ENERGY AND SUPPORT DEEPER SURFACE REFLECTIONS THOUGH THE
TIMING/PLACEMENT OF THE FRONT/SHEAR AXIS REMAINS WELL ALIGNED.
THE UKMET ACTUALLY ROLLS UP THE LAMINAR VORTICITY/SHEAR AXIS INTO
TWO DEEPER CONSOLIDATED WAVES BY TUES OVER CHICAGO AND THE
BOUNDARY WATERS OF MN/ONTARIO.    THE 12Z CMC THOUGH SIMILAR
EVOLUTION IN CANADA APPEARS TO BE EJECTING QUITE A BIT OF
SHORTWAVE ENERGY THROUGH THE ROCKIES INTO THE PLAINS WHILE
RETAINING A STRONGER (THOUGH BIFURCATED) RIDGE ACROSS THE ENTIRE
SOUTHERN US.  WITH CONVECTIVE FEEDBACK POCKETS...IT SEEMS QUITE
UNREALISTIC AT THIS POINT.

ALL CONSIDERED THROUGH CANADA AND THE CENTRAL PLAINS...A 00Z
NAM/GFS AND 12Z ECMWF BLEND WILL REMAIN PREFERRED GIVEN GOOD
AGREEMENT/CONTINUITY AND STRONG GEFS/ECENS ENSEMBLE SUPPORT.
CONFIDENCE IS SLIGHTLY ABOVE AVERAGE.


SECOND CLOSED LOW REACHING THE PAC NORTHWEST MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM IS A BIT FURTHER NORTH WITH THE SMALL TUTT-LIKE
FEATURE AND CONNECTED TROUGHING ACROSS N CA/OR BY THE END OF THE
PERIOD.  STILL THIS IS ALL WELL WITHIN THE REALM OF POSSIBILITY
AND GIVEN THE HIGH ALIGNMENT OF THE SHAPE/TIMING/STRENGTH OF THE
FEATURES BY END OF DAY THREE...WILL SUPPORT AN OPERATIONAL BLEND
AT ABOVE AVERAGE CONFIDENCE.

GALLINA


...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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