MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1248 AM EDT THU MAR 20 2014 VALID MAR 20/0000 UTC THRU MAR 23/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 00Z NAM/GFS ALONG WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS. ...UPPER TROF EVENTUALLY CLOSING OFF OVER THE INTERIOR NORTHEAST EARLY IN THE PERIOD... ...FRONTAL ZONE EXITING THE EAST COAST... PRELIMINARY PREFERENCE: NON-00Z NAM/12Z CMC SOLUTION FORECAST CONFIDENCE: ABOVE AVERAGE A BROAD AREA OF HEIGHT FALLS MOVING FROM THE UPPER MIDWEST/GREAT LAKES REGION WILL LIFT NORTHEASTWARD IN TIME WHERE THE SYSTEM IS FORECAST TO CLOSE OFF AND FURTHER INTENSIFY. THE 00Z NAM/GFS AND 18Z GEFS/21Z SREF MEANS ARE A LITTLE MORE AGGRESSIVE ALOFT WITH THE DEEPENING PROCESS. HOWEVER...THESE DIFFERENCES ARE PRIMARILY AS THE SYSTEM LIFTS INTO EASTERN QUEBEC. LOOKING TO THE SURFACE...THE 00Z NAM/12Z CMC ARE RATHER STRONG WITH A SURFACE LOW LIFTING NORTHWARD ALONG COASTAL NEW ENGLAND. THE ENSEMBLE LOW PLOTS DO NOT REALLY SHOW ANY SIGN OF DEVELOPMENT THERE SO WILL BE RELUCTANT TO FAVOR EITHER OF THE EXTREME NAM/CMC SOLUTIONS. A NON-00Z NAM/12Z CMC WILL BE THE PREFERRED SOLUTION. ...SHORTWAVE MIGRATING FROM THE UPPER INTERMOUNTAIN WEST TOWARD THE GREAT LAKES THROUGH 22/0600Z... ...SURFACE LOW TRACKING ALONG THE NORTHERN TIER STATES... PRELIMINARY PREFERENCE: BLEND OF THE 12Z ECMWF/UKMET FORECAST CONFIDENCE: AVERAGE A SHORTWAVE CURRENTLY SEEN ON WATER VAPOR IMAGERY MOVING TOWARD THE UPPER INTERMOUNTAIN WEST WILL QUICKLY REACH THE DAKOTAS BY LATE THURSDAY NIGHT. THE INTENSITY OF THE SYSTEM SHOULD NOT CHANGE A WHOLE LOT DURING THE PERIOD AS EVIDENCED BY THE NEARLY STEADY STATE PRESSURE OF THE SURFACE CYCLONE. ONLY 24 HOURS INTO THE FORECAST...THERE ARE SOME DIFFERENCES VISIBLE IN THE GUIDANCE WITH REGARD TO TIMING. THE 00Z NAM/21Z SREF MEAN ARE SLIGHTLY FASTER WITH THE STRONGER CLUSTERING SEEN BETWEEN THE 12Z ECMWF/CMC/UKMET AND 12Z ECMWF ENSEMBLE MEAN. SANDWICHED IN BETWEEN THESE PAIR OF SUBTLE EXTREMES ARE THE 00Z GFS/18Z GEFS MEAN. THIS MODEL SPREAD SLOWLY INCREASES IN TIME WITH THE RESPECTIVE MODELS HOLDING STEADY WITH THEIR PLACEMENT IN THE HIERARCHY. CONSIDERING THE LOW TRACK...THE ENSEMBLE LOW PLOTS SHOW THE ECMWF MEMBERS HAVE BEEN MUCH MORE STABLE IN THE PAST COUPLE CYCLES WITH THE 12Z GEFS MEMBERS MOST RECENTLY JOINING THIS SOLUTION. THE WPC PREFERENCE WILL LEAN ON THAT SOLUTION WITH THE 12Z UKMET SUPPORTING IT AS WELL. ...SHEARING IMPULSE MOVING ACROSS SOUTHERN CA ON FRIDAY MORNING... ...ENERGY SLIDING UNDERNEATH TOWARD WEST TX BY 21/1200Z... PRELIMINARY PREFERENCE: GENERAL MODEL CONSENSUS FOR THE SHEARING SHORTWAVE...BLEND OF THE 00Z GFS/12Z ECMWF FOR THE ADDITIONAL ENERGY FORECAST CONFIDENCE: HIGH...AND SLIGHTLY ABOVE AVERAGE FOR THE OTHER SYSTEM MODELS DEPICT A SHORTWAVE CROSSING THE DESERT SOUTHWEST DURING THE PERIOD WITH MINIMAL IMPACTS TO THE REGION GIVEN A LACK OF MOISTURE. GUIDANCE IS IN FULL AGREEMENT THAT THE WAVE WILL QUICKLY SHEAR APART SO A MODEL CONSENSUS SOLUTION WILL SUFFICE. TO THE SOUTH...A QUICK MOVING BATCH OF ENERGY WILL LIFT NORTH AND EAST REACHING THE SOUTHERN ROCKIES BY EARLY FRIDAY MORNING. WHILE THE 00Z NAM FOLLOWS THE PATH OF THE 00Z GFS/12Z ECMWF...IT DOES SO WITH A MUCH MORE INTENSE LOOKING WAVE. DO LIKE THE IDEA THESE MODELS FOLLOW GIVEN THEY ARE SUPPORTED WELL BY THE ENSEMBLE MEANS. HOWEVER...WILL REMOVE THE 00Z NAM GIVEN ITS MORE EXTREME LOOKING NATURE. ...LONGWAVE TROF SETTING UP FROM THE PACIFIC NORTHWEST OVER TO THE GREAT LAKES BY SUNDAY MORNING... PRELIMINARY PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF WITH THE 18Z GEFS/12Z ECMWF ENSEMBLE MEANS FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE TOWARD THE LATTER HALF OF THE WEEKEND...A LONGWAVE TROF WILL BEGIN TO SET UP ACROSS A MAJORITY OF THE NORTHERN TIER OF THE COUNTRY. THERE ARE DEFINITELY TWO DIFFERENT CAMPS WHICH APPEAR WITH THIS SYSTEM WITH THE 00Z NAM/12Z CMC BEING MORE TO THE SOUTHWEST WITH THE EXTENT OF THE LONGWAVE ENERGY. FURTHER DOWNSTREAM...THE 12Z UKMET DOES NOT SHOW AS MUCH AMPLIFICATION TO THE FLOW AS THE 00Z GFS/12Z ECMWF AND THEIR RESPECTIVE ENSEMBLE MEANS DEPICT. WHILE THE 00Z NAM/12Z CMC ARE WELL OFF TO THE WEST...THEY ARE MORE AMPLIFIED THAN THE FLATTER 12Z UKMET. SPAGHETTI PLOTS AGREE THAT THE 12Z UKMET IS A LOWER PROBABILITY SOLUTION SO WILL FAVOR SOMETHING CLOSER TO THE 00Z GFS/12Z ECMWF AND THEIR MEANS. www.wpc.ncep.noaa.gov/html/model2.shtml... RUBIN-OSTER