260
FXUS10 KWNH 091618
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1217 PM EDT WED OCT 09 2019
VALID OCT 09/1200 UTC THRU OCT 13/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
09/12Z NAM/GFS EVALUATION WITH PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..EAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ANY OF THE OPERATIONAL MODELS
A STACKED, CLOSED LOW FORMING THE LOWER PART OF A REX BLOCK WILL
LINGER WITH RAIN OVER NEW ENGLAND BEFORE BEING PRODDED ALONG BY
THE UPSTREAM CENTRAL U.S. CYCLONE. THE 12Z GFS TRENDED MORE IN
LINE WITH THE OTHER OPERATIONAL MODELS, MAKING FOR A STRONG
CONSENSUS AND THE ABILITY TO USE ANY OF THE OPERATIONAL MODELS FOR
THIS SYSTEM THROUGH DAY 3.
..CENTRAL U.S. MID-LATITUDE CYCLONE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ANY OF THE OPERATIONAL MODELS, DROPPING THE GFS AFTER
12/00Z
A VERY DEEP, 2 TO 3 STANDARD DEVIATION TROUGH, WILL SPIN UP INTO A
LARGE SCALE CYCLONE WITH LOW PRESSURE TRACKING FROM COLORADO
TOWARD NORTHERN MINNESOTA DURING THE MATURING PHASE, AND THEN
LINGERING IN PLACE BENEATH A BUILDING SHORTWAVE RIDGE OVER CANADA.
POTENTIALLY RECORD-BREAKING OCTOBER SNOWFALL IS POSSIBLE IN PARTS
OF THE PLAINS, ALONG WITH STRONG WINDS. THE MODELS ARE IN VERY
GOOD AGREEMENT WITH THIS LARGE SCALE STORM WITHIN THE UPPER AIR
NETWORK. THE *BEST* CONSENSUS CLUSTERS AROUND THE ECMWF ENSEMBLE
MEAN, AND SO WOULD INCLUDE MOST OF THE OPERATIONAL MODELS THROUGH
DAY 3. THE EXCEPTION IS THE GFS WHICH TENDS TO CHANGE SHAPE ON DAY
3, WITH ENERGY ROTATING AROUND AND DRAGGING THE MATURE CYCLONE
TOWARD THE GREAT LAKES SOMEWHAT UNREALISTICALLY.
..WEST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 12Z NAM / 00Z ECMWF
A COMPLICATED MERGER OF TWO STREAMS AROUND 145 DEGREES WEST LEADS
EVENTUALLY TO A MORE CONSOLIDATED OPEN TROUGH APPROACHING THE WEST
COAST BY DAY 3. SOME SOLUTIONS SPLIT THE ENERGY AGAIN, WITH
EMPHASIS ON A SOUTHERN STREAM TROUGH ANCHORED OFF CALIFORNIA, AND
A LOW AMPLITUDE NORTHERN STREAM WAVE PUNCHING INTO THE NORTHWEST.
WE PREFER SOLUTIONS THAT ARE CLOSER TO THE ECMWF MEAN, GIVEN ITS
HANDLING OF THE NORTH AMERICAN PATTERN AS A WHOLE, AND BASED ON
SYNOPTIC REASONING INVOLVING DIFFERENTIAL ADVECTION OVER THE
PACIFIC. THE OPERATIONAL ECMWF MAY BE A BIT TOO SLOW AND
CONSOLIDATED, AND THE NAM A BIT TOO FAST, BUT A BLEND OF THE TWO
GETS CLOSE TO THE EC MEAN, AND IS A DECENT REPRESENTATION OF
CONSENSUS.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
BURKE
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