MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 231 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 CMC/UKMET/ECMWF ALONG WITH FINAL 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... FINAL PREFERENCE: GENERAL MODEL COMPROMISE 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 00Z 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 OTHER GUIDANCE APPEARS TO HAVE JOINED THE 00Z NAM/12Z CMC WITH A MORE DEVELOPED LOW CENTER STRADDLING COASTAL NEW ENGLAND. AS THE LATEST ENSEMBLE LOW PLOTS ARE FROM THE 12Z CYCLE...THEY DO NOT SHOW MUCH DEVELOPMENT AT 20/1200Z. GIVEN THE OVERWHELMING SHIFT IN THE GUIDANCE...WILL LEAN ON A GENERAL MODEL COMPROMISE FOR THIS SYSTEM. ...SHORTWAVE MIGRATING FROM THE UPPER INTERMOUNTAIN WEST TOWARD THE GREAT LAKES THROUGH 22/0600Z... ...SURFACE LOW TRACKING ALONG THE NORTHERN TIER STATES... FINAL PREFERENCE: BLEND OF THE 00Z 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 WHILE THE 00Z CMC/UKMET/ECMWF AND 12Z ECMWF ENSEMBLE MEAN HAVE TENDED TO FAVOR SOMETHING SLOWER. SANDWICHED IN BETWEEN THESE PAIR OF SUBTLE EXTREMES ARE THE 00Z GFS/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 00Z UKMET GENERALLY SUPPORTING IT AS WELL. ...SHEARING IMPULSE MOVING ACROSS SOUTHERN CA ON FRIDAY MORNING... ...ENERGY SLIDING UNDERNEATH TOWARD WEST TX BY 21/1200Z... FINAL PREFERENCE: GENERAL MODEL CONSENSUS FOR THE SHEARING SHORTWAVE...BLEND OF THE 00Z GFS/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/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... FINAL PREFERENCE: BLEND OF THE 00Z GFS/ECMWF/UKMET 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/CMC BEING MORE TO THE SOUTHWEST WITH THE EXTENT OF THE LONGWAVE ENERGY. FURTHER DOWNSTREAM...THE 00Z UKMET HAS SHIFTED TOWARD A MORE AMPLIFIED SOLUTION WHICH IS MUCH MORE SIMILAR TO THE 00Z GFS/ECMWF. THIS TRIO OF MODELS HAVE DECENT AGREEMENT WITH THE ENSEMBLE MEANS...ALBEIT WITH SOME DIFFERENCES IN TIMING. THE SPAGHETTI PLOTS SUPPORT THE TREND SEEN IN THE 00Z UKMET WHICH BRINGS IT TOWARD THE BETTER CLUSTERED SOLUTIONS. THE PREFERENCE WILL BE A COMBINATION OF THE 00Z GFS/ECMWF/UKMET. WILL MAINTAIN THE CONFIDENCE AT SLIGHTLY BELOW AVERAGE AS GUIDANCE CONTINUES TO TREND AND SHIFT FROM RUN TO RUN. www.wpc.ncep.noaa.gov/html/model2.shtml... RUBIN-OSTER