MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1129 AM EST THU JAN 09 2014 VALID JAN 09/1200 UTC THRU JAN 13/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS NO SIGNIFICANT INITIALIZATION ERRORS APPEAR TO BE IMPACTING THE SHORT RANGE FORECAST. ...WEAK SHORTWAVE TRACKING ACROSS THE PLAINS TODAY AND CROSSING THE NORTHERN MID-ATLANTIC EARLY FRI... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE LATEST MODELS REMAIN IN VERY GOOD AGREEMENT WITH THE STRENGTH AND TIMING OF THIS SYS...SUCH THAT A GENERAL MODEL COMPROMISE CAN BE USED TO RESOLVE SMALLER SCALE DIFFERENCES. ...PROGRESSIVE UPPER TROUGH REACHING THE MS/OH VALLEYS BY SAT...GOING NEG-TILT ALONG THE EAST COAST BY SUN... PREFERENCE: 12Z GFS CONFIDENCE: AVERAGE THE LATEST MODELS CONTINUE TO ADVERTISE AN UPPER TROUGH AND ASSOCD FRONT ADVANCING RAPIDLY EAST OUT ACROSS THE PLAINS AND MS VLY LATER TONIGHT AND FRI...AND THEN MOVING INTO THE EASTERN U.S. SAT AND SUN WHILE GRADUALLY AMPLIFYING AND GOING NEG TILT. THE TREND OVER THE LAST COUPLE OF DAYS TO BE MORE PROGRESSIVE WITH THIS TROUGH...WITH LESS SPLIT FLOW...CONTINUES TO BE THE THEME ATTM. THE 12Z NAM AND 12Z GFS ARE RELATIVELY SPEAKING THE MOST PROGRESSIVE WITH THE TROUGH AXIS AND ASSOCD FRONT...INCLUDING AN INTENSIFYING SFC LOW THAT WILL ADVANCE NEWD OUT OF THE MIDWEST FRI AND ACROSS THE GREAT LAKES ON SAT BEFORE LIFTING INTO ONTARIO SUN. THE 00Z GEM GLOBAL AND 00Z ECMWF ARE JUST A TAD SLOWER. INTERESTINGLY...THE 00Z UKMET IS RATHER FAST WITH ITS SFC LOW LIKE THE NAM AND GFS...BUT IS SLOWEST WITH ITS TROUGH AXIS AND FRONT. BASED ON UPSTREAM TRENDS TO BE MORE PROGRESSIVE WITH ENERGY ACROSS THE EASTERN PACIFIC OCEAN AND WESTERN U.S....WILL FAVOR THE MORE PROGRESSIVE MODELS WITH THIS SYS...LED BY THE 12Z GFS. ...WEAK SHORTWAVE/FRONT REACHING THE PACIFIC NORTHWEST BY TONIGHT... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THERE IS VERY GOOD AGREEMENT WITH THE LATEST MODELS IN HANDLING THE LARGE SCALE ASPECT OF THIS FEATURE. WILL FAVOR A GENERAL MODEL COMPROMISE TO RESOLVE ANY LINGERING SMALLER SCALE DIFFS. ...INTENSE UPPER TROUGH/CLOSED LOW RAPIDLY CROSSING THE NORTHWEST FRI NIGHT AND SAT... ...ENERGY ADVANCING DOWNSTREAM ACROSS SOUTHERN CANADA AND THE CENTRAL U.S. THROUGH SUN... PREFERENCE: 12Z GFS/00Z ECMWF/00Z UKMET BLEND CONFIDENCE: AVERAGE THE MODELS SHOW STRONG UPSTREAM ZONAL FLOW SOUTH OF THE ALEUTIANS WITH EMBEDDED VORT ENERGY THAT WILL AMPLIFY VIGOROUSLY SOUTH OF THE GULF OF AK FRI AND TOWARD THE NORTHWEST U.S. BY SAT. ALL OF THE MODELS SHOW A VERY PROGRESSIVE SYS...BUT INDICATE INTENSE SFC LOW PRESSURE AND BROAD AND VERY STRONG WIND FIELD IMPACTING THE NORTHWEST FRI NIGHT/SAT. THEREAFTER...RATHER STRONG LOW PRESSURE WILL REDEVELOP IN THE LEE OF THE CANADIAN ROCKIES AND CROSS SOUTHERN CANADA. A TRAILING PACIFIC FRONT WILL ADVANCE EAST OUT OF THE WESTERN U.S. AND THROUGH THE PLAINS FOR SUN. THE 12Z NAM AND 00Z GEM GLOBAL DO NOT SHOW QUITE AS ROBUST OF AN UPPER TROUGH/CLOSED LOW DEVELOPING SOUTH OF THE GULF OF AK AND OFFSHORE THE NORTHWEST U.S. OVER THE NEXT COUPLE OF DAYS. CONSEQUENTLY...THEY TEND TO HAVE SLIGHTLY MORE PROGRESSIVE/FLATTER SOLNS VS THE INTENSE BUT STILL VERY PROGRESSIVE 12Z GFS...00Z UKMET AND 00Z ECMWF SOLNS. BASED ON THE MODEL TRENDS OF A MORE INTENSE JET CORE AND POWERFUL SFC LOW CENTER...WILL FAVOR THE GFS/ECMWF/UKMET CAMP. ALL OF THE MODELS HAVE GENERALLY TRENDED MORE PROGRESSIVE AS WELL...BUT THE NAM/GEM GLOBAL SOLNS LIKELY ARE LACKING A LITTLE BIT ON THEIR INTENSITY AND DEPTH OF THE SYS. ...WARM FRONT ARRIVING ACROSS THE PACIFIC NORTHWEST BY LATE SUN... PREFERENCE: 12Z NAM/12Z GFS BLEND CONFIDENCE: AVERAGE IN THE WAKE OF THE POWERFUL TROUGH/SFC LOW IMPACTING THE NORTHWEST ON SAT...A WARM FRONT IS SUGGESTED BY THE MODELS TO ARRIVE ACROSS THE PACIFIC NORTHWEST BY LATE SUN. VERY FAST ZONAL UPSTREAM FLOW ACROSS THE CENTRAL/EASTERN PACIFIC OCEAN WILL FAVOR THIS FRONT ARRIVING QUICKLY. THE 00Z UKMET WAS RELATIVELY THE SLOWEST SOLN. THE 12Z NAM AND 12Z GFS WERE THE MOST PROGRESSIVE...WITH THE 00Z ECMWF AND 00Z GEM GLOBAL TIGHTLY CLUSTERED IN BETWEEN. BASED ON SUCH FAST UPSTREAM FLOW AND A LACK OF ANY AMPLIFYING SHORTWAVE SOUTH OF THE ALEUTIANS OR GULF OF AK...THE FASTER NAM/GFS WILL BE PREFERRED WITH THIS FEATURE. www.wpc.ncep.noaa.gov/html/model2.shtml... ORRISON