MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT WED MAY 22 2013

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

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


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


DEEP CYCLONE OVER THE NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  GENERAL MODEL COMPROMISE

THE GUIDANCE IS IN VERY GOOD AGREEMENT WITH THIS SYSTEM THROUGH
THE FIRST 60 HRS OF THE FCST PERIOD WITH THE 500MB CLOSED LOW
WALLOWING OVER WA/OR AND A SHORT WAVE IMPULSE ROTATING FROM NRN CA
AT 12Z/23 TO MT/NRN PLAINS 12Z/24. AFTER 60 HRS... THERE ARE
SLIGHT DIFFERENCES... AS THE CLOSED LOW LIFTS UP INTO WRN CANADA
AND ANOTHER MID TO UPPER LOW FROM THE NERN PAC DROPS TOWARD THE
NW. RIGHT NOW WPC FEELS COMFORTABLE FOLLOWING THE MODEL
BLEND/COMPROMISE THROUGH 60HRS AND STAYING CLOSE TO THE ECMWF/EC
MEAN ON SAT.


LARGE SYSTEM MOVING FROM THE MIDWEST TO THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  12Z GFS AND 00Z/22 ECMWF BLEND

A COMPLEX AND WET PATTERN SETTING UP FOR THE UPCOMING WEEKEND FOR
THE NERN QUAD OF THE COUNTRY... AS MULTIPLE NRN STREAM SHORT WAVES
INTERACT WITH THE CURRENT TROUGH FROM THE MIDWEST... WHILE
DOWNSTREAM RIDGING BUILDS OVER THE NRN ATLANTIC TO BECOME BLOCKING
AND ANOMALOUS. THE GUIDANCE AS A WHOLE IS IN SOLID AGREEMENT
THROUGH THE FIRST 60 HRS OF THE FCST PERIOD OR TILL 00Z/25... AS
THE MS VLY TROUGH SLIDES EASTWARD WHILE A NRN STREAM SHORT WAVE
TROUGH INTERACTS/PHASES TO INDUCE A POSSIBLE CLOSED 500MB LOW OVER
THE ERN OH VLY TO THE DELMARVA. THEN AFTER 60HRS OR THROUGH SAT...
THE GUIDANCE BEGINS TO SHOW SOME SPREAD AND WPC PREFERS THE SLOWER
SOLUTIONS OF THE GFS/ECMWF OVER THE NAM/SREF MEAN AND EC MEAN.
THIS MEANS ADDITIONAL NRN STREAM DYNAMICS DIG AND PHASE WITH THE
INTENSIFYING SYSTEM... AS THE UPPER TROUGH NEG TILTS AND THE 500MB
LOW CENTER DRIFTS TO THE NNW FROM DELMARVA COAST TO SRN NEW
ENGLAND. THE ONLY DIFFERENCE BETWEEN THE ECMWF AND GFS IS THE
ECMWF IS A BIT DEEPER ALOFT BUT THIS DOES NOT SEEM TO TRANSLATE
DOWN TO THE SURFACE. NOW THE 12Z VERSION OF THE ECMWF HAS TRENDED
EVEN A BIT SLOWER/DEEPER THAN ITS PREVIOUS RUN. OVERALL... STILL
FEEL COMFORTABLE WITH THE BLEND OF THE GFS AND 00Z/22 ECMWF
THROUGHOUT.


...MODEL TREND GRAPHICS AT
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
...500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

MUSHER