Prognostic Meteorological Discussion
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FXUS10 KWNH 020504
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
103 AM EDT TUE JUN 02 2015

VALID JUN 02/0000 UTC THRU JUN 05/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

WELL DEVELOPED NORTHERN STREAM UPPER LOW ROLLING ACROSS NEW ENGLAND
WEAK SURFACE LOW AFFECTING MID-ATLANTIC THRU COASTAL NEW ENGLAND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF OPERATIONAL MODELS
CONFIDENCE: ABOVE AVERAGE

A WELL DEVELOPED AND CONSOLIDATED UPPER LOW ALONG THE
ONTARIO/QUEBEC BORDER SHIFTS SHIFTS EASTWARD CLIPPING NORTHERN NEW
ENGLAND TUESDAY INTO WEDNESDAY EVENTUALLY PULLING A WEAK SURFACE
REFLECTION OUT THE MID-ATLANTIC AND DEEPENING IT OFF NOVA SCOTIA.
THE MODELS CONTINUE TO SHOW VERY GOOD AGREEMENT WITH PLACE AND
INTENSITY FOR THE LARGER SCALE FEATURE UNTIL THE SYSTEM IS OUT OF
CONUS ON WEDNESDAY NIGHT.  A BLEND OF THE OPERATIONAL MODEL RUNS
IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE.


SLOW MOVING CLOSED LOW OVER TENNESSEE RIVER VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 00Z NAM/GFS AND 12Z ECMWF ENSEMBLE MEAN
CONFIDENCE: ABOVE AVERAGE THROUGH 00Z WED... SLIGHTLY BELOW
AVERAGE AFTER

A WELL DEFINED UPPER LOW CURRENTLY CENTERED ON THE CENTRAL
KENTUCKY/TENNESSEE BORDER SLOWLY SHIFTS EASTWARD ACROSS THE
SOUTHERN APPALACHIANS INTO THE CAROLINAS. THERE IS FAIRLY GOOD
AGREEMENT WITH THE TRACK AND DEPTH OF THE CLOSED LOW UNTIL ABOUT
12Z WEDNESDAY.  THE 00Z NAM/GFS MAY BE STARTING A TREND OF
BROADENING THE TROF TO THE EAST AS IT SHOWS PULSES OF SHORTWAVE
ENERGY EJECTING OUT OF BROAD SOUTHWESTERLY FLOW FROM THE WESTERN
CARIBBEAN.  CURRENT CONVECTIVE TRENDS IN THE VICINITY GIVE SOME
CREDENCE TO THIS SOLUTION OF CARIBBEAN INFLUENCE. ADDITIONAL
CONFIDENCE IS ADDED WITH A HANDFUL OF 12Z ECMWF ENSEMBLE MEMBERS
HINTING THIS DIRECTION AS WELL. THE 12Z UKMET SEEMS TO OPEN THE
TROF AND WEAKEN IT A BIT TOO QUICK WHILE THE 12Z CMC IS SLOWER
KEEPING MORE ENERGY IN THE BASE OF THE UPPER TROF AS A CLOSED
LOW...ELIMINATING THEM FROM THE PREFERRED BLEND OF THE 00Z NAM/GFS
WITH INCLUSION OF THE 12Z ECMWF ENSEMBLE MEAN TO HELP TEMPER THE
LARGER SHIFT.


SHORTWAVE SHEARING OUT ALONG U.S./CANADIAN BOARDER
NORTHERN HIGH PLAINS CYCLOGENESIS
SOUTHERN STREAM SHORTWAVE EJECTING INTO CENTRAL PLAINS THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 00Z NAM/GFS
CONFIDENCE: AVERAGE

ENERGY AT THE BASE OF NEGATIVE TILT PACIFIC TROF AT THE BEGINNING
OF THE PERIOD IS EJECTING ACROSS THE NORTHERN U.S. ROCKIES
EVENTUALLY SHEARING OUT ALONG THE U.S. CANADIAN BOARDER BY DAY 2.
A SURFACE LOW OVER EASTERN MONTANA MOVES EASTWARD AND BEGINS TO
WEAKEN INTO AN SOUTHWEST TO NORTHEAST ORIENTED SURFACE TROF NEAR
WESTERN LAKE SUPERIOR BY WEDNESDAY AFTERNOON.  THIS SURFACE TROF
CONNECTS TO A PERSISTENT CYCLONE ALONG THE COLORADO HIGH PLAINS
UNTIL SHIFTING EAST AND WEAKENING AS SUBTLE SHORTWAVE EJECTS AND
SPINS UP OVER NEBRASKA ON THURSDAY.  THE 12Z CMC APPEARS TO BE THE
MOST OUT OF PHASE WITH THE OTHER OPERATIONAL GUIDANCE AS IT OVER
AMPLIFIES AN UPPER LEVEL TROF ACROSS MINNESOTA BY DAY 3 WITH A
MUCH STRONGER SURFACE REFLECTION.

THE 12Z ECMWF ALSO SEEMS A BIT TOO STRONG WITH SOME POTENTIAL
CONVECTIVE FEEDBACK INTO SHORTWAVE EJECTING ON DAY 3 ACROSS THE
CENTRAL PLAINS. GIVEN THE TIMING OF THE EJECTION...FORCING
CONVECTION AROUND THE 06Z TIME FRAME LENDS LESS CREDIBILITY FOR
ITS SOLUTION THOUGH IT IS WEAK.  LEAVING THE 00Z GFS/NAM WHICH IN
GOOD AGREEMENT WITH THE GEFS MEANS BUT ALSO WITHIN SOME OF THE 12Z
ECMWF ENSEMBLE MEMBERS THROUGH DAY 3. IT REMAIN A BIT SLOWER AND
LESS AMPLIFIED THAN THE 12Z ECWMF WITH THE EJECTION OF THE
SHORTWAVE INTO CENTRAL PLAINS ON THURSDAY BUT IS SUPPORTED WITH A
STRONG CLUSTERING OF GEFS SOLUTIONS PROVIDING BETTER CONFIDENCE
ESPECIALLY GIVEN BETTER TIMING OF WITH CONVECTIVE RESPONSE.


UPPER TROUGH RELOADING OVER THE WEST BY WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

STRONG PACIFIC WESTERLY JET ENTERS THE PACIFIC COASTAL ZONE BY
WEDNESDAY DROPPING A BULK OF ENERGY INTO THE DEEPENING OF UPPER
LEVEL LOW ALONG THE CALIFORNIA COAST BY THE END OF THE FORECAST
PERIOD.  REMARKABLE ECMWF AND NAEFS ENSEMBLE AGREEMENT IN THE
EVOLUTION OF THIS SYSTEM.  THE GEFS MEMBERS ALONG WITH THE GFS
HAVE BEEN THE WESTERN MEMBERS WHILE THE CMC MEMBERS THE FURTHEST
EAST. THE 12Z CMC CONTINUES TO BE THE MOST PROGRESSIVE OUTLIER AND
SHOULD BE USED WITH CAUTION....BUT THE 00Z NAM/GFS AND 12Z ECMWF
ALL APPEAR TO BE GOOD REPRESENTATIVES TO PROVIDE SLIGHTLY ABOVE
AVERAGE CONFIDENCE.


...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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