MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1152 AM EST TUE JAN 28 2014 VALID JAN 28/1200 UTC THRU FEB 01/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ...AN EVALUATION OF THE 12Z NAM/GFS ALONG WITH PRELIMINARY PREFERENCES/FORECAST CONFIDENCE... THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS. ...CLOSED LOW EJECTING OUT OF THE SOUTHERN GULF OF BAJA CA/SEA OF CORTEZ EARLY IN THE PERIOD... PRELIMINARY PREFERENCE: ANY AVAILABLE DETERMINISTIC SOLUTION FORECAST CONFIDENCE: ABOVE AVERAGE INITIALLY A CLOSED 570-DM LOW WILL CROSS INTO WEST-CENTRAL MEXICO THIS MORNING WHILE QUICKLY EVOLVING INTO MORE OF AN OPEN WAVE. THIS ENERGY EVENTUALLY BECOMES INGESTED INTO THE LONGWAVE TROF INHABITING THE EASTERN U.S. BY WEDNESDAY AFTERNOON. IN GENERAL DIFFERENCES ARE SMALL AMONG THE GUIDANCE WHILE ONLY NOTING THE FACT THE 06Z GEFS/09Z SREF MEANS 500-MB HEIGHT FIELDS SHOW A LITTLE BIT MORE SUPPRESSION. WILL FAVOR ANY DETERMINISTIC SOLUTION HERE. ...MEAN UPPER TROF EXITING THE EASTERN U.S. ...ASSOCIATED COLD FRONT PUSHING WELL INTO THE OPEN ATLANTIC... PRELIMINARY PREFERENCE: MODEL COMPROMISE BETWEEN THE 12Z GFS AND 00Z ECMWF/UKMET FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE AS A LOBE OF POLAR VORTEX LIFTS NORTHWARD...THE REMAINDER OF THE UPPER TROF WILL GRADUALLY SLIDE EASTWARD WHICH SHOULD CONTINUE TO USHER THE SURFACE FRONT FURTHER OUT TO SEA. THE INITIAL ENERGY APPEARS TO BE WELL AGREED UPON THROUGH WEDNESDAY MORNING AS IT MOVES THROUGH THE UPPER MID-ATLANTIC. LOOKING UPSTREAM...TIMING DIFFERENCES EMERGE...PARTICULARLY AS THE WEAK SHORTWAVE SLIDES INTO THE LOWER MID-ATLANTIC BY EARLY THURSDAY. SUFFICIENT CLUSTERING IS NOTED WHICH INCLUDES THE 12Z GFS AND 00Z ECMWF/UKMET ALONG WITH THE 06Z GEFS/00Z ECMWF ENSEMBLE MEANS. THE 12Z NAM IS DEFINITELY ON THE SLOWER END WHILE THE 00Z CMC REMAINS ON THE FLATTER SIDE WITH THE WAVE. WPC WILL FAVOR SOLUTIONS WITHIN THE STRONGER CLUSTERING SO A MODEL COMPROMISE BETWEEN THE 12Z GFS AND 00Z ECMWF/UKMET IS RECOMMENDED. SUCH AN IDEA ALSO IS DEPICTED REASONABLY AT THE SURFACE. ...COMPACT UPPER LOW CROSSING SOUTHWESTERN ONTARIO BY 30/0600Z... ...REINFORCING SHOT OF COLD AIR TO THE NORTHERN TIER... PRELIMINARY PREFERENCE: BLEND OF THE 00Z UKMET WITH THE 00Z ECMWF/ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE: AVERAGE WITH BROAD CYCLONIC FLOW CONTINUING TO ANCHOR THE NORTHEASTERN SECTOR OF THE CONTINENT...YET ANOTHER DEEP CLOSED LOW IS EXPECTED TO NEAR THE INTERNATIONAL BORDER WITH CANADA BY MID-WEEK. MODELS DEPICT THIS COMPACT LOW CENTER TO CROSS THE MANITOBA/ONTARIO BORDER BY 30/0000Z WITH THE SYSTEM GATHERING STRENGTH AS IT DIPS BELOW 500-DM BY EARLY THURSDAY. INITIAL THOUGHTS ARE THE 12Z NAM APPEARS TOO FAST BY THURSDAY AS RACES AHEAD OF THE ENSEMBLE MEANS. EVENTUALLY THIS UPPER LOW LIFTS WELL AWAY FROM THE CONUS SO WILL FOCUS A BIT MORE ON THE PROGRESSION OF THE SURFACE FRONT CROSSING THE CENTRAL U.S. BY THURSDAY AFTERNOON/EVENING...THE 12Z GFS/06Z GEFS MEAN BECOMES A BIT FASTER WITH THE POSITION OF THE BOUNDARY RELATIVE TO THE ECMWF SUITE. AS THE 540-DM SPAGHETTI PLOT INDICATES THE 00Z GEFS MEMBERS HAVE MORE SPREAD ON THE EASTERN SIDE OF THE ENVELOPE VERSUS THE BETTER CONSOLIDATION SEEN THE 00Z ECMWF ENSEMBLE MEMBERS. THINKING THE GEFS MAY BE A BIT QUICK GIVEN ITS FASTER OUTLYING MEMBERS ARE SLIDING ITS SOLUTION FURTHER EAST. WITH ALL THIS SAID...WILL FOLLOW THE LEAD OF THE 00Z ECMWF/ECMWF ENSEMBLE MEAN WITH THE 00Z UKMET ADDED AS IT TENDS TO AGREE WITH THIS EVOLUTION. ...COMPLEX ARRAY OF ENERGY AFFECTING THE WESTERN U.S. THROUGHOUT THE WORK WEEK... ...EVENTUAL FRONTAL ZONE SETTING UP FROM THE FOUR CORNERS INTO THE SOUTHERN PLAINS AND TN/OH VALLEYS... PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF FORECAST CONFIDENCE: INITIALLY SLIGHTLY BELOW AVERAGE...BECOMING BELOW AVERAGE LATER IN THE PERIOD THE MEAN UPPER RIDGE WHICH HAS CONTINUED TO HOLD STRONG ACROSS THE EASTERN PACIFIC/WEST COAST IS EXPECTED TO FINALLY BREAKDOWN AS A MYRIAD OF SHORTWAVES BOMBARD THE WESTERN U.S. THE INITIAL BATCH OF ENERGY WHICH WILL AFFECT THE PACIFIC NORTHWEST WILL SLIDE THE WEST COAST WITH SOME OF THE SHORTWAVE ENERGY ADVANCING INTO THE INTERIOR MOUNTAIN WEST. FURTHER TO THE NORTH...ANOTHER ROUND OF HEIGHT FALLS ARE FORECAST TO DIVE DOWN FROM VANCOUVER ISLAND HELPING MAINTAIN A TROF OVER THE REGION THROUGH FRIDAY. MODEL AGREEMENT IS REASONABLE THROUGH 30/1200Z...BUT UNCERTAINTY IS NOTED OVER THE EASTERN PACIFIC WITH THE TROF ENERGY DROPPING SOUTHWARD. THE 00Z CMC/ECMWF/ECMWF ENSEMBLE MEAN ARE SLOWER IN ADVANCING THIS SHORTWAVE ENERGY INLAND RELATIVE TO THE QUICKER NCEP GUIDANCE. SUCH UNCERTAINTY IS DEFINITELY WELL REPRESENTED BY THE 552-DM SPAGHETTI PLOT WITH THE 00Z ECMWF ENSEMBLE MEMBERS FAVORING THE MORE WESTERN SOLUTION. WILL STAY MORE CONSERVATIVE AT THIS POINT AND GO BETWEEN THE TWO SOLUTIONS FAVORING A BLEND OF THE 12Z GFS/00Z ECMWF. PLACEMENT OF THE DEVELOPING SURFACE LOW IN THE SOUTHERN HIGH PLAINS WITH THE ASSOCIATED BAROCLINIC ZONE STRETCHING NORTHEASTWARD TOWARD THE LOWER MO VALLEY. ON THE SOUTHERN SIDE OF THE ENVELOPE WITH THE PLACEMENT OF THE FRONT ARE THE 12Z NAM/GFS AND 00Z UKMET WHILE THE 00Z ECMWF/UKMET ARE ON THE NORTHERN END. UNFORTUNATELY MODEL RUN-TO-RUN CONTINUITY IS NOT GREAT SO THIS IS DEFINITELY A DIFFICULT FORECAST. FOR NOW WILL SPLIT BETWEEN THE TWO CAMPS AND STICK WITH THE EARLIER PREFERENCE OF THE 12Z GFS/00Z ECMWF WITH CONFIDENCE RAPIDLY DIMINISHING. ...POTENTIAL LONGWAVE TROF REACHING THE NORTHERN ROCKIES/HIGH PLAINS BY 01/0000Z... PRELIMINARY PREFERENCE: BLEND OF THE 00Z ECMWF WITH THE 06Z GEFS/00Z ECMWF ENSEMBLE MEANS FORECAST CONFIDENCE: BELOW AVERAGE ANOTHER NORTHERN STREAM SYSTEM IS EXPECTED TO NEAR THE NORTHERN TIER OF THE COUNTRY BY FRIDAY. THE MODEL SPREAD IS RATHER HIGH ALTHOUGH THERE IS SOME CLUSTERING NOTED WHICH INCLUDES THE 00Z ECMWF/ECMWF ENSEMBLE MEAN ALONG WITH THE 06Z GEFS MEAN. THE PREFERENCE WILL FOLLOW THE CLUSTER WITH POTENTIAL CHANGES IN THE NEXT PACKAGE PENDING THE NEXT ROUND OF 12Z MODELS. www.wpc.ncep.noaa.gov/html/model2.shtml... RUBIN-OSTER