MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1205 PM EDT SAT OCT 18 2014 VALID OCT 18/1200 UTC THRU OCT 22/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE TROUGH DIGGING INTO THE OH VALLEY/MID-ATLANTIC/NEW ENGLAND THROUGH SUN... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS INDICATE ANOTHER SHORTWAVE DIGGING RATHER SHARPLY ACROSS THE OH VLY AND INTO THE MID-ATLANTIC LATER TODAY AND SUN. THE ENERGY IS EXPECTED TO GO NEG TILT OVER SRN NEW ENGLAND ON SUN...AND THERE IS EVIDENCE TO SUGGEST THAT THIS WILL INVIGORATE A SFC LOW OFFSHORE NEW ENGLAND THAT WILL LIFT UP INTO NOVA SCOTIA. THE 12Z NAM IS SEEN AS BEING A SOMEWHAT SLOWER AND DEEPER OUTLIER SOLN. WILL PREFER A NON-NAM CONSENSUS. ...SHORTWAVE TROUGH AMPLIFYING INTO THE OH VALLEY/NORTHEAST MON AND TUES... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: AVERAGE GIVEN THE STRENGTHENING LARGE SCALE RIDGE JUST UPSTREAM OVER INTERMOUNTAIN WEST AND SOUTHWEST CANADA BY SUN...THE MODELS SUPPORT THE IDEA OF ANOTHER SHORTWAVE IMPULSE ALONG WITH A WEAK AREA OF LOW PRESSURE DIGGING DOWN INTO UPR MS VALLEY BY LATE SUN. THIS SHORTWAVE IS EXPECTED TO AMPLIFY RATHER VIGOROUSLY INTO THE OH VLY/NORTHEAST MON AND TUES. THE 12Z UKMET IS A BIT FASTER THAN THE MULTI-MODEL CONSENSUS UNTIL TUES WHEN IT COMES INTO BETTER TOLERANCE WITH THE NAM/GFS/GEM AND ECMWF SOLNS. WILL FAVOR A NON-UKMET CONSENSUS ATTM GIVEN REASONABLY GOOD MODEL CLUSTERING SEEN WITH THE REMAINING GUIDANCE. ...SPLIT FLOW UPPER TROUGH CURRENTLY MOVING INTO THE WEST... ...SOUTHERN STREAM CLOSED LOW OVER THE SOUTHWEST BY SUN AND MON... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE A SPLIT FLOW UPPER TROUGH WILL MOVE INTO THE WEST TONIGHT AND SAT...WITH NORTHERN STREAM ENERGY QUICKLY BREAKING AWAY AND SHEARING EAST ACROSS THE NORTHERN ROCKIES AND OUT INTO THE NORTHERN PLAINS. MEANWHILE...A MORE SUBSTANTIAL PORTION OF THE ORIGINAL TROUGH WILL DIG SOUTHEAST ACROSS CA AND INTO THE SOUTHWEST THROUGH SUN RESULTING IN A SOUTHERN STREAM CLOSED LOW. THE MODELS DEPICT GOOD AGREEMENT ALOFT ON THE LARGER SCALE WITH THIS SYS...SO A GENERAL MODEL COMPROMISE WILL BE PREFERRED. ...DEEP LONGWAVE TROUGH APPROACHING THE WEST COAST BY SUN AND MON... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS AGREE IN DEVELOPING A SIGNIFICANT LONGWAVE TROUGH OFFSHORE THE WEST COAST BY LATER SUN AS A RIDGE BUILDS DOWNSTREAM OVER THE INTERMOUNTAIN WEST AND PUSHES OUT INTO THE PLAINS. ON THE LARGER SCALE...THERE IS PRETTY GOOD AGREEMENT WITH THE LATEST GUIDANCE. THE 12Z UKMET THOUGH IS A TAD FASTER TO BRING THE HEIGHT FALLS INLAND. THE REMAINING MODELS ARE WELL CLUSTERED ENOUGH THAT A NON-UKMET CONSENSUS WILL SUFFICE. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON