Prognostic Meteorological Discussion
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FXUS10 KWNH 230459
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1158 PM EST SAT NOV 22 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 NAM/GFS ALONG WITH PRELIMINARY
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...

PRELIMINARY PREFERENCE: BLEND OF THE 12Z UKMET/ECMWF ENSEMBLE MEAN
FORECAST CONFIDENCE: SLIGHTLY BELOW 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/12Z CMC CONTINUE TO PORTRAY A SLOWER SOLUTION AS THE WAVE
LIFTS UP THROUGH THE TN/OH VALLEYS AND INTO THE GREAT LAKES
REGION. THE 00Z GFS AND 12Z 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. THERE ARE CONCERNS THAT THE 12Z
ECMWF IS TOO WEAK AND QUICK WITH THE PROGRESSION OF THIS LOW AS IT
MOVES UP INTO WESTERN QUEBEC. THE 12Z UKMET APPEARS TO MIMIC THE
18Z GEFS/12Z ECMWF ENSEMBLE MEAN THROUGHOUT MUCH OF THE PERIOD.
THE 00Z GFS CONTINUES TO BE DEEPER WITH ITS SOLUTION AND MUCH MORE
PROGRESSIVE WITH THE EASTWARD PUSH OF THE BAROCLINIC ZONE. WPC
WILL LEAN ON THE 12Z UKMET/ECMWF ENSEMBLE MEAN AT THIS POINT WITH
FUTURE MODIFICATIONS POSSIBLE.


...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...

PRELIMINARY PREFERENCE: BLEND OF THE 18Z 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. THE LATTER MORE ELONGATED
BATCH OF SHORTWAVE ENERGY IS ALSO NOTED IN THE 12Z UKMET AS WELL.
ENSEMBLE SPAGHETTI PLOTS SUGGEST A MORE CONSOLIDATED SYSTEM IN
CONTRAST WITH THE 00Z NAM/12Z UKMET SOLUTIONS. 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. UNCERTAINTY IS 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...

PRELIMINARY PREFERENCE: BLEND OF THE 12Z ECMWF/UKMET
FORECAST CONFIDENCE: AVERAGE

A NORTHERN STREAM SYSTEM IS EXPECTED TO DROP DOWN FROM
ALBERTA/SASKATECHEWAN REACHING THE NORTHERN TIER OF THE CONUS BY
LATE TUESDAY. MODEL DIFFERENCES ARE NOTED WITH THE 00Z NAM BEING
SLOWER WHILE THE 00Z GFS IS MUCH QUICKER. THE LATTER SEEMS TO BE
OUTSIDE THE CONSENSUS FORMING AMONG THE 12Z ECMWF/UKMET AND
PERHAPS THE 00Z GFS PARALLEL. WILL FAVOR A COMBINATION OF THE 12Z
ECMWF/UKMET HERE.


...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

$$




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