THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


MODEL DIAGNOSTIC DISCUSSION


[Abbreviations and acronyms used in this product]
Geographic boundaries:    Map 1- [Color] [B/W Print Version]      Map 2 - [Color] [B/W Print Version]



MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
141 AM EST SUN NOV 23 2014

VALID NOV 23/0000 UTC THRU NOV 26/1200 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

...AN EVALUATION OF THE 00Z MODEL GUIDANCE ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...INITIAL SHORTWAVE CROSSING THE LOWER MS VALLEY BY 23/1200Z...
...DEEP SURFACE CYCLONE MOVING THROUGH THE GREAT LAKES...
...STRONG MID-LATITUDE TROF/SURFACE COLD FRONT...

FINAL PREFERENCE: BLEND OF THE 00Z UKMET/ECMWF
FORECAST CONFIDENCE: AVERAGE

A PRONOUNCED MID-LEVEL IMPULSE CURRENTLY SEEN ON WATER VAPOR
IMAGERY MOVING INTO SOUTH TX HAS SPREAD ABUNDANT HEAVY RAINFALL TO
THE SOUTHERN PLAINS/WESTERN GULF COAST. AS IN PREVIOUS DAYS...THE
00Z NAM CONTINUES TO PORTRAY A SLOWER SOLUTION AS THE WAVE LIFTS
UP THROUGH THE TN/OH VALLEYS AND INTO THE GREAT LAKES REGION. THE
00Z GFS/ECMWF/UKMET OFFER A REASONABLE SOLUTION WHICH FITS WITHIN
THE STRONGER MODEL CLUSTERING. MUCH OF THE UNCERTAINTY REVOLVES
AROUND THE STRENGTH AND SPEED OF THE RAPIDLY DEEPENING SURFACE
CYCLONE. AFTER REVIEWING THE AVAILABLE 00Z GUIDANCE...THE 00Z
UKMET/ECMWF APPEAR TO MIMIC ONE ANOTHER WITH A SLIGHTLY WEAKER
SOLUTION THAN WHAT THE PREVIOUS UKMET RUN SHOWED. THIS SUBTLE
SHIFT CARRIES THESE SOLUTIONS AWAY FROM THE SLOWER ENSEMBLE MEANS.
GIVEN THE 00Z UKMET/ECMWF FALL WELL WITHIN THE ENSEMBLE
SPREAD...THIS APPEARS TO BE PLAUSIBLE. WILL CONTINUE TO LEAN AWAY
FROM THE 00Z GFS WHICH IS DEEPER AND MUCH MORE PROGRESSIVE WITH
THE BAROCLINIC ZONE. THE FAVORED SOLUTION IS A BLEND OF THE 00Z
UKMET/ECMWF.


...AMPLIFIED SHORTWAVE TRAVERSING THE GULF COAST BY MID-WEEK...
...DEVELOPING SURFACE LOW MOVING FROM THE EASTERN GULF OF MX TO
THE SOUTHEASTERN U.S. COAST...

FINAL PREFERENCE: BLEND OF THE 00Z GEFS/12Z ECMWF ENSEMBLE MEANS
FORECAST CONFIDENCE: BELOW AVERAGE

HEIGHT FALLS CURRENTLY JUST WEST OF THE BRITISH COLUMBIA COAST
WILL WORK THEIR WAY INLAND BY 23/1800Z. MODELS AGREE THE SYSTEM
SHOULD EVENTUALLY GET EMBEDDED WITHIN THE BROAD LONGWAVE TROF
ANCHORING THE CENTRAL TO EASTERN U.S. THE SOUTHEASTWARD
PROGRESSION CARRIES THE AMPLIFIED FLOW TOWARD THE WESTERN GULF
COAST BY EARLY TUESDAY. THE EARLY OUTLIER IS THE 00Z NAM WHICH IS
SLOWER WITH THE MID-LEVEL PATTERN WHILE ALSO DEPICTING VORTICITY
THAT IS MORE SPRAWLED OUT IN NATURE. ENSEMBLE SPAGHETTI PLOTS
SUGGEST A MORE CONSOLIDATED SYSTEM IN CONTRAST WITH THE 00Z NAM
SOLUTION. THERE ARE OF COURSE PLENTY OF DIFFERENCES REGARDING
STRENGTH AND TIMING...ESPECIALLY BETWEEN THE RESPECTIVE ENSEMBLE
MEMBERS AS WELL. THE PAST COUPLE 564-DM SPAGHETTI PLOTS SHOW THE
TENDENCY OF THE ECMWF ENSEMBLE MEMBERS TO BE SLOWER/MORE AMPLIFIED
RELATIVE TO THE GEFS/CMC ENSEMBLE MEMBERS. THE UNCERTAINTY GROWS
THROUGH MID-WEEK WITH THE 00Z GFS QUICKER WITH THE SYSTEM AS IT
MOVES INTO THE SOUTHERN APPALACHIANS WHILE OTHER SOLUTIONS ARE
FARTHER SOUTH TOWARD THE GULF COAST. REGARDING THE SURFACE LOW
TRACK...THE 00Z ECMWF/UKMET HAVE COME IN BEING THE MOST WESTERN
SOLUTIONS...MORE OR LESS STRADDLING THE COAST. THESE FORECASTS ARE
WEST OF THE ALL OF THE ENSEMBLE MEANS INCLUDING THE 12Z ECMWF
ENSEMBLE MEAN WHICH IS THE FARTHEST WEST AMONG THE ENSEMBLES.
UNCERTAINTY REMAINS RATHER HIGH WITH POSSIBLE RAMIFICATIONS OF A
WINTER STORM ACROSS SECTIONS OF THE EASTERN U.S. OF COURSE THERE
ARE PLENTY OF DETAILS TO RESOLVE BEFORE ANYTHING MORE CLEAR CUT
CAN BE STATED. ULTIMATELY WILL LEAN ON THE ENSEMBLE MEANS AS A
GUIDE HERE AND BLEND THEM EQUALLY UNTIL THE MODELS BETTER HANDLE
THIS SYSTEM. AS THE KEY SHORTWAVE IS STILL OVER WATER...HOPEFULLY
BETTER SAMPLING WILL TAKE PLACE ONCE THE SYSTEM MOVES INLAND BY
SUNDAY AFTERNOON.


...PRONOUNCED FRONTAL SYSTEM CROSSING THE NORTHERN PLAINS BY
26/0000Z...

FINAL PREFERENCE: BLEND OF THE 00Z NAM/ECMWF...2/3 TOWARD THE 00Z
ECMWF
FORECAST CONFIDENCE: AVERAGE

A NORTHERN STREAM SYSTEM IS EXPECTED TO DROP DOWN FROM
ALBERTA/SASKATCHEWAN REACHING THE NORTHERN TIER OF THE CONUS BY
LATE TUESDAY. MODEL DIFFERENCES ARE NOTED WITH THE 00Z GFS BEING
MUCH QUICKER. THIS SOLUTION SEEMS TO BE OUTSIDE THE CONSENSUS
FORMED BY THE 00Z NAM/ECMWF. HAD PREVIOUSLY REJECTED THE 00Z NAM
BEING SLOW BUT IT APPEARS TO MAKE ENOUGH OF AN ADJUSTMENT TO CATCH
UP TO OTHER MODELS BY DAY 3. WPC WILL FAVOR A BLEND OF THE 00Z
NAM/ECMWF WITH MORE EMPHASIS ON THE 00Z ECMWF.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

RUBIN-OSTER





Last Updated: 141 AM EST SUN NOV 23 2014