Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8

000
FXUS10 KWNH 221705
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
104 PM EDT FRI MAY 22 2015

VALID MAY 22/1200 UTC THRU MAY 26/0000 UTC

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

12Z MODEL EVALUATION WITH PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


SYSTEM MOVING FROM THE SOUTHWEST INTO NRN HIGH PLAINS SUN/MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY DAY 1-2 PREFERENCE: NON-UKMET BLEND
PRELIMINARY DAY 3 PREFERENCE: BLEND OF 00Z ECMWF ENSEMBLE MEAN/00Z
GEFS MEAN
CONFIDENCE: AVERAGE

A LARGE BROAD TROF EXISTS OVER THE WEST WITH THREE FOCI ROTATING
AROUND THE CENTROID NEAR SE ID/N UT. THE INITIAL AND LARGEST WAVE
EJECTS INTO THE GREAT PLAINS SUNDAY INTO MONDAY. THE NAM AND GFS
ARE CONSISTENTLY LEFT OF CONSENSUS WITH THE SURFACE LOW TRACK.
THEY ARE STRONGER AND FURTHER NORTH OWING TO EMPHASIS ON ENERGY
ALOFT EJECTING FROM THE BASE OF THE TROUGH TOWARD THE NORTHERN
PLAINS. THE ECMWF HAS BEEN CONSISTENTLY MORE SUPPRESSED OR TO THE
SOUTH AND EAST OF CONSENSUS. A GOOD AMOUNT OF SPREAD STILL EXISTS
IN THE ENSEMBLE SUITES. THE 00Z GEFS/ECMWF ENSEMBLE MEANS BLEND A
NICE COMPROMISE.


SYSTEM ALONG WEST COAST INTO AZ/NM BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: BLEND OF 12Z GFS/00Z ECMWF ENSEMBLE
MEAN/00Z GEFS MEAN
CONFIDENCE: ABOVE AVERAGE

A SECOND WAVE DROPS DOWN THE WESTERN SIDE OF THE TROF SATURDAY
NIGHT INTO THE BASE BY THE END OF THE PERIOD... MOST GUIDANCE IS
IN QUITE GOOD AGREEMENT IN THE EVOLUTION PARTICULARLY UNTIL EARLY
MONDAY.  SOME SUBTLE DISAGREEMENT STARTS ON MONDAY WHEN AS THE 12Z
NAM/GFS/CMC APPEAR A BIT MORE AMPLIFIED WHILE THE 00Z ECMWF IS A
BIT DAMPENED.  BY THE END OF THE PERIOD THE DIFFERENCES ARE NOT
SIGNIFICANT ENOUGH TO DISMISS ANY PARTICULAR OPERATIONAL MODEL
EXCEPT THE UKMET.


SYSTEM DEVELOPING ALONG THE PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRELIMINARY PREFERENCE: NON-UKMET BLEND
CONFIDENCE: ABOVE AVERAGE

UPSTREAM ENERGY BREAKS THROUGH THE NARROWING RIDGE ACROSS
NORTHWEST CANADA AND DEVELOPS THE CANADIAN PACIFIC TROF INTO A
BETTER DEFINED LOW OVER THE NORTHWEST U.S. BY DAY 3.  VERY GOOD
AGREEMENT OF THIS SOLUTION IN TIMING AND INTENSITY EXCEPT FOR THE
UKMET.  12Z NAM IS ALSO A BIT PROGRESSIVE TOWARD THE END OF THE
PERIOD BUT STILL REMAINS A VIABLE SOLUTION.

...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
$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.