MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1222 PM EDT MON JUL 20 2015 VALID JUL 20/1200 UTC THRU JUL 24/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z NAM/GFS MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO IMPACT THEIR SHORT RANGE FORECASTS. GREAT BASIN SHORTWAVE AND MID LEVEL CIRCULATION OF POST-TROPICAL CYCLONE DOLORES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF OPERATIONAL MODELS CONFIDENCE: ABOVE AVERAGE DEEPENING SHORTWAVE SEEN WELL NEAR ID/UT/NV ALONG WITH MID-LEVEL ENERGY FROM POST-TROPICAL CYCLONE DOLORES SEEN ACROSS S NV APPEAR TO BE RESOLVED WELL BY THE GLOBAL MODELS PARTICULARLY IN TIMING AS IT BEGINS TO CROSS THE CENTRAL U.S. RIDGE THURSDAY. ENSEMBLE MODEL SPREAD EXISTS MAINLY IN ASSOCIATION WITH THE DEPTH OF THE SHORTWAVE AS THEY PHASE. THE 12Z NAM AND 00Z ECMWF ARE THE STRONGEST/MOST CONSOLIDATED RESOLVING THE SHORTWAVE ON THE DEEPER SIDE OF THE SOLUTIONS WHILE THE 00Z CMC/UKMET ARE FLATTER AND WEAKER WITH MORE OF A SHEAR ZONE. A GENERAL BLEND WILL FLATTEN OUT THE SOLUTION BUT GIVEN THE AGREEMENT WITH TIMING AND ENSEMBLE MEAN SUPPORT THIS IS PREFERRED AT ABOVE AVERAGE CONFIDENCE. THERE REMAIN DISTINCT MESOSCALE DETAIL DIFFERENCES WITHIN THIS FLOW REGIME ACROSS THE WEST TRANSLATING EASTWARD INTO THE PLAINS HAVING SIGNIFICANT IMPACTS ON PRECIPITATION FROM THE CNTRL/SRN ROCKIES TO THE LOWER AND MIDDLE MISSISSIPPI RIVER VALLEY. FOR FURTHER DETAILS...PLEASE REFER TO THE WPC QPF DISCUSSION FOR DAYS 1-3...AWIPS HEADER...NFDQFPFD. UPPER TROUGH OVER THE PACIFIC NORTHWEST TUE-THUR ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CMC BLEND CONFIDENCE: ABOVE AVERAGE VERY STRONG AGREEMENT WITH EVOLUTION OF THE WESTERN TROF WITH SMALL DIFFERENCES IN THE DEPTH THROUGH 23/00Z (WED NIGHT). AS THE TROF FILLS AND LIFTS...AS ONE WOULD EXPECT...SLIGHT TIMING/DEPTH ISSUES BEGIN TO BECOME MORE NOTICEABLE. THE 00Z CMC BECOMES A BIT MORE PROGRESSIVE SHIFTING EAST BREAKING FROM OTHER GUIDANCE. OTHERWISE...THOUGH THE SPREAD INCREASES A BIT...IT IS FAIRLY GOOD FOR DAY 3 AND OTHER THAN SMALL DIFFERENCES WITH THE FILLING THE 12Z NAM/GFS SHOW GOOD AGREEMENT WITH THE 00Z ECMWF/UKMET/ECMWF ENSEMBLE MEAN AND 06Z GEFS ENSEMBLE MEAN. AS SUCH A NON-CMC BLEND IS PREFERRED AT ABOVE AVERAGE CONFIDENCE. UPPER LEVEL LOW AND ASSOCIATED COLD FRONT MOVING THROUGH THE GREAT LAKES AND INTO NORTHEAST BY LATE WEEK ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF OPERATIONAL MODELS CONFIDENCE: ABOVE AVERAGE VERY STRONG AGREEMENT OF THE OPERATIONAL MODELS SUPPORTED BY THE ENSEMBLE SPREAD/MEANS CONTINUES WITH THE EVOLUTION OF THE UPPER LOW SHIFTING FROM JAMES BAY TOWARD NORTHERN NEW ENGLAND BY THE END OF THE PERIOD. THIS IS CONTINUED THROUGH MUCH OF THE DEPTH THROUGH THE SURFACE...WHERE THE EAST COAST TROF/COLD FRONT IS SLOW TO ADVANCE UNTIL THE COLD FRONT ACROSS THE GREAT LAKES REGION SHIFTS THROUGH TO THE EAST COAST BY WED. THIS PROVIDES ABOVE AVERAGE CONFIDENCE TO THE SUITE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... GALLINA