MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 236 PM EDT SUN JUN 22 2014 VALID JUN 22/1200 UTC THRU JUN 26/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. INCREASING TROUGHING IN THE WEST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE OUTSIDE THE 12Z UKMET, THE GUIDANCE CONTINUES TO SHOW REASONABLY GOOD AGREEMENT WITH A PAIR OF MID-LEVEL SHORTWAVES AND A SURFACE LOW MOVING INTO WESTERN CANADA/THE PACIFIC NORTHWEST, AS WELL AS A 700 HPA TROUGH REMAINING ACROSS THE DESERT SOUTHWEST. A GENERAL MODEL COMPROMISE IS ADVISED WITH ABOVE AVERAGE CONFIDENCE CONSIDERING THE MINIMAL SPREAD IN THE GUIDANCE. CENTRAL PLAINS/OH VALLEY/GREAT LAKES/NORTHEAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: ECMWF/UKMET/CANADIAN COMPROMISE CONFIDENCE: ABOVE AVERAGE THE 12Z GFS USES A GRIDSCALE FEEDBACK BULL'S EYE TO STRENGTHEN A 500/700 HPA TROUGH MUCH MORE THAN THE OTHER GUIDANCE THIS AFTERNOON, WHICH CONTINUES THROUGH THE FORECAST CYCLONE. THIS DISTORTS ITS PRESSURE PATTERN ACROSS THE PLAINS AND MIDWEST. CONVECTIVE FEEDBACK ASIDE, SINCE THE FLOW IS NEARLY ZONAL ACROSS THIS REGION, A LESS AMPLIFIED SOLUTION WOULD BE PREFERRED. THE 12Z NAM IS MORE AMPLIFIED WITH A SYSTEM ALOFT MOVING OUT OF THE GREAT LAKES, WHICH IS ONE OF ITS USUAL BIASES. A COMPROMISE OF THE 12Z ECMWF/12Z UKMET/12Z CANADIAN IS ADVISED FOR MASS FIELDS. FOR QPF THOUGHTS, SEE OUR QUANTITATIVE PRECIPITATION GRAPHICS AND DISCUSSION. SHORTWAVES MOVING ACROSS THE SOUTHEAST/GULF COAST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: AVERAGE THE GUIDANCE MASS FIELDS ARE IN REASONABLY GOOD AGREEMENT WITH TWO SHORTWAVES MOVING THROUGH THE REGION. THE PREFERENCE IS FOR A GENERAL MODEL COMPROMISE WITH ABOVE AVERAGE CONFIDENCE. FOR QPF THOUGHTS, SEE OUR QUANTITATIVE PRECIPITATION GRAPHICS AND DISCUSSION. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH