804
FXUS10 KWNH 231841
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
141 PM EST MON NOV 23 2009
VALID NOV 23/1200 UTC THRU NOV 27/0000 UTC
...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR
INGEST...
FINAL 12Z MODEL EVALUATION INCLUDING THE ECMWF
MODEL INITIALIZATION ERRORS DO NOT APPEAR TO BE LARGE ENOUGH TO
HAVE A SIGNIFICANT IMPACT ON THE FORECAST.
..SYSTEM EDGING INTO THE WEST ON THU
PREFERENCE: GFS/CANADIAN GLBL COMPROMISE WITH THE SFC WAVE...
GFS/UKMET BLEND ALOFT
BY THU THE GFS IS SLIGHTLY FASTER THAN THE NAM WITH LEADING HGT
FALLS ALOFT... WHILE THE NAM IS SOMEWHAT WEAKER AND A LITTLE
FASTER THAN THE GFS WITH THE SFC WAVE THAT REACHES THE PAC NW
COAST BY F84 LATE THU. ADDING THE 12Z UKMET/CANADIAN GLBL SOLNS
YIELD A RELATIVE CONSENSUS THAT BRINGS A WAVE NEAR THE OREGON
COAST BY F84 LATE THU... ALBEIT WITH A NEARLY 10 MB SPREAD ON
DEPTH. STILL THE NEW 12Z ECMWF IS AN EXTREMELY DEEP OUTLIER
COMPARED TO OTHER SOLNS AND ON THE SLOW EDGE OF GUIDANCE INCLUDING
THE 00Z ECMWF ENSEMBLE MEAN. THE 00Z ECMWF WAS ON THE SLOW EDGE
OF GUIDANCE AS WELL. THERE IS ENOUGH OF A STRONGER TREND IN
GUIDANCE TO LEAN AWAY FROM THE LATEST SREF/GEFS/ECMWF ENSEMBLE
MEANS WHICH MAY BE TOO WEAK DUE TO NOT ACCOUNTING ADEQUATELY FOR
IMPORTANT SMALLER SCALE DETAILS. PREFER A COMPROMISE BETWEEN THE
GFS/CANADIAN GLBL FOR THE SFC FCST. THE GFS/CMC MAY BE A LITTLE
TOO FAST WITH PORTIONS OF THE MID LVL TROF... SO WILL RECOMMEND A
GFS/UKMET BLEND ALOFT.
..SFC LOW TRACKING FROM THE PLAINS INTO THE GRTLKS
..UPR TROF/ASSOC SFC FRONT REACHING THE NRN PLAINS TUE
PREFERENCE: COMPROMISE AMONG NAM/UKMET/CANADIAN GLBL/ECMWF...
EXCEPT EXCLUDING THE NAM ALONG EAST COAST BY LATE WED-THU
DURING THE DAY WED THE NAM SHOWS MORE EWD AMPLITUDE THAN THE GFS
AND MOST OTHER SOLNS WITH THE LEADING SHRTWV TROF THAT CROSSES
AREAS FROM THE ERN GRTLKS SEWD. THEN THE GFS IS FARTHER SWWD AND
WEAKER THAN THE NAM WITH THE TRAILING UPPER LOW THAT REACHES THE
OH VALLEY/GRTLKS BY THU. AS A RESULT THE OVERALL TROF AXIS IN THE
GFS ENDS UP FARTHER WWD THAN THE NAM FCST. DIFFS ALOFT CAUSE THE
NAM TO BECOME DEEPER THAN THE GFS WITH THE SFC LOW AS IT TRACKS
INTO THE GRTLKS. WHILE THE 06Z/00Z GEFS MEANS AND SOME 09Z SREF
MEMBERS OFFER SOME DEGREE OF SUPPORT FOR THE GFS HANDLING OF THE
SECOND SYSTEM... THE UKMET/CANADIAN GLBL AND FAIRLY CONSISTENT
ECMWF SHOW A MID LVL CLOSED LOW TRACK CLOSER TO THE NAM. HOWEVER
MODEL/ENSEMBLE CONSENSUS INDICATES THE NAM COULD BE A FRACTION
DEEP WITH THE CORE OF THE SYSTEM... AND IS LIKELY TOO AGGRESSIVE
WITH LEADING HGT FALLS ALOFT NEAR THE EAST COAST BY WED-THU. AS
FOR NAM/GFS TRENDS... THE NAM HAS DISPLAYED A FASTER TREND OVER
THE PAST DAY. THE GFS HAS ADJUSTED MODESTLY FASTER VERSUS 06Z/00Z
RUNS BUT REMAINS SLOWER THAN YDAYS 12Z GFS. THESE TRENDS ALONG
WITH CURRENT CONSENSUS SEEM TO FAVOR LEANING MORE TO THE NAM THAN
GFS EXCEPT FOR LEADING HGT FALLS NEAR THE EAST COAST... WITH AN
ULTIMATE PREFERENCE BEING A NAM/UKMET/CANADIAN GLBL/ECMWF
COMPROMISE TO LEAN AWAY FROM THE GFS FCST AND TO MITIGATE SOMEWHAT
EXTREME TRAITS OF THE NAM AT SOME FCST HRS.
..LOW PRESSURE DEVELOPING NEAR THE EAST COAST WED-THU
PREFERENCE: COMPROMISE AMONG CANADIAN GLBL/UKMET/ECMWF
DUE TO THE NAM BEING FASTER TO BRING HGT FALLS ALOFT TO THE EAST
COAST... THE NAM IS FARTHER N/NE THAN THE GFS WITH WRN ATLC LOW
PRESSURE. THE NAM IS ON THE NERN EDGE OF THE CURRENT
MODEL/ENSEMBLE SPREAD AND WILL BE DISCOUNTED SINCE ITS MID LVL
SOLN ALSO DOES NOT COMPARE WELL TO OTHER SOLNS. MEANWHILE THE
AVERAGE OF REMAINING MODEL/ENSEMBLE GUIDANCE IS SLIGHTLY SWWD OF
THE GFS... WITH THE UKMET/CANADIAN GLBL/ECMWF ALL IN CLOSE
PROXIMITY BY LATE THU BUT WITH THE UKMET DEEPER THAN OTHER SOLNS.
WITH FURTHER SUPPORT FROM THE 12Z GEFS MEAN... PREFER AN AVERAGE
AMONG THE CANADIAN GLBL/UKMET/ECMWF.
..SYSTEM OFF THE MID ATLC/NORTHEAST COAST MON-WED
PREFERENCE: CANADIAN GLBL/ECMWF COMPROMISE
THE GFS GRADUALLY TRACKS THE SYSTEM FARTHER N/E VERSUS THE NAM.
LATEST MODEL/ENSEMBLE SOLNS DISPLAY ENOUGH SPREAD TO INCLUDE BOTH
THE GFS AND NAM AS POTENTIAL SOLNS. PROGRESSIVE SWLY FLOW ALOFT
COULD FAVOR FASTER TIMING THAN THE NAM... BUT THE 12Z ECMWF HAS
ADJUSTED SLOWER FROM ITS PREVIOUS RUN TO A NAM-LIKE SOLN. THE
UKMET IS ALSO FAIRLY SLOW BUT IS WEAKER THAN OTHER GUIDANCE WITH
THE LEADING MID LVL SHRTWV ENERGY. MEANWHILE THE CANADIAN
GLBL/REG GEM INDICATE POTENTIAL FOR A SLIGHTLY STRONGER SYSTEM
THAN OTHER SOLNS DURING TUE-TUE NIGHT... WITH AN INTERMEDIATE
TRACK. THE 12Z GEFS/00Z ECMWF ENSEMBLE MEANS LEAN TO THE MIDDLE
OR SLOWER PORTION OF THE GUIDANCE SPREAD. GIVEN THE SPREAD AND
CONTINUITY CHANGES IN RECENT GUIDANCE PREFER A MODERATE SOLN
REPRESENTED BY A CANADIAN GLBL/ECMWF COMPROMISE.
...MODEL TREND GRAPHICS AT
WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
..500MB FORECASTS AT WWW.HPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
RAUSCH
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