Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Air Quality
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
   Satellite Images
   National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Accomplishments
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
Model Diagnostics Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1839Z Aug 31, 2014)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 PM EDT SUN AUG 31 2014

VALID AUG 31/1200 UTC THRU SEP 04/0000 UTC

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

...AN EVALUATION OF THE 12Z CMC/UKMET/ECMWF ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...AREA OF HEIGHT FALLS MOVING THROUGH THE LOWER GREAT
LAKES/NORTHEASTERN U.S...

FINAL PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: ABOVE AVERAGE

A PAIR OF SHORTWAVES MOVING THROUGH THE LOWER GREAT LAKES AND OH
VALLEY...RESPECTIVELY...WILL EVENTUALLY REACH THE NORTHEASTERN
U.S. BY LATER TONIGHT. THE FORMER WAVE SHOULD REMAIN MORE INTACT
RELATIVE TO THE OH VALLEY IMPULSE WHICH WILL BE A LITTLE MORE
SHEARED IN NATURE. GIVEN THE LIMITED TIME THIS SYSTEM AFFECTS THE
CONUS...THE MODELS ARE IN CLOSE ENOUGH AGREEMENT TO AFFORD A
GENERAL MODEL COMPROMISE HERE.


...LONGWAVE TROF EXTENDING FROM THE ROCKIES THROUGH THE GREAT
LAKES...
...PROGRESSIVE COLD FRONT...

FINAL PREFERENCE: BLEND OF THE 12Z GEFS/09Z SREF/00Z ECMWF
ENSEMBLE MEANS
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

WATER VAPOR IMAGERY SHOWED A LONGWAVE TROF INITIALLY SPANNING MUCH
OF THE WESTERN TO CENTRAL U.S. WITH SEVERAL EMBEDDED SHORTWAVES
RACING TOWARD THE NORTH AND EAST. THE LEAD ENERGY AND ITS
ACCOMPANYING SPEED MAX TRACKING TOWARD THE MIDDLE MS VALLEY WILL
CARRY AN INHERENT HEAVY RAINFALL AND SEVERE WEATHER THREAT. EARLY
ON...THE 12Z GFS APPEARS A TAD QUICKER ALOFT AND AT THE SURFACE
WITH THE BAROCLINIC ZONE. OTHER MODELS APPEAR TOLERABLE WITHIN THE
GENERAL NOISE THROUGH MONDAY WITH THIS SHORTWAVE. AS THIS SYSTEM
LIFTS ACROSS THE CANADIAN BORDER ADDITIONAL LONGWAVE ENERGY WILL
FILL IN ACROSS THE CENTRAL U.S. THE 12Z NCEP GUIDANCE ARE A TAD
QUICKER RELATIVE TO THE 12Z ECMWF/CMC/UKMET WITH THIS ASPECT OF
THE TROF. AT THE SURFACE...THE ENSEMBLE MEANS ALL ARE FAIRLY CLOSE
TO ANOTHER THROUGH 02/0000Z WITH THE POSITION OF THE FRONT AND
AREA OF LOW PRESSURE OVER ONTARIO. ALL AND ALL...THE ENSEMBLE
MEANS SEEM TO AFFORD THE BEST COMPROMISE AS THE 12Z GUIDANCE HAS
SHOWN MORE VARIATION IN THEIR SOLUTIONS. WILL SWITCH OVER TO A
BLEND OF THE MEANS WITH CONFIDENCE REDUCED BUT STILL A BIT ABOVE
AVERAGE GIVEN THE ENSEMBLE AGREEMENT.


...AMPLIFIED SHORTWAVE REACHING THE PACIFIC NORTHWEST BY TUESDAY
AFTERNOON...

FINAL PREFERENCE: BLEND OF THE 12Z GFS/CMC/ECMWF
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

AS THE LONGWAVE TROF BEGINS TO EJECT EASTWARD...ADDITIONAL
SHORTWAVE ENERGY IS FORECAST TO DROP DOWN FROM THE NORTHEAST
PACIFIC AND BRING AN AMPLIFIED SYSTEM INTO THE PACIFIC NORTHWEST
BY TUESDAY AFTERNOON. BY MID-WEEK THE 12Z NAM LOOKS TOO SLOW AND
IS WEST OF THE ENSEMBLE MEANS INCLUDING THE 09Z SREF MEAN. THE
564-DM SPAGHETTI PLOT SHOWS AGREEMENT THAT A POSITIVELY-TILTED
TROF WILL BE LOCATED OVER THE NORTHERN GREAT BASIN/ROCKIES WITH
SOME SPREAD REGARDING TIMING AND HOW MUCH ENERGY HANGS BACK TOWARD
THE SOUTHWEST. THE ENSEMBLE MEANS ACTUALLY DIVERGE FROM ONE
ANOTHER A BIT MORE THAN PREVIOUSLY AS THE 12Z GEFS MEAN IS WELL
AHEAD OF THE DETERMINISTIC 12Z GFS ALONG WITH ANY OTHER SOLUTION.
BELIEVE THE 12Z GEFS MEAN MAY BE TOO FAST. OVERALL...THE 12Z
CMC/ECMWF ARE IN A SLIGHTLY SLOWER CAMP WHILE THE 12Z GFS/UKMET
ARE OFF TO THE EAST. BY 04/0000Z...THE 12Z UKMET BECOMES FASTER SO
WILL LEAN A BIT MORE HEAVILY ON THE CLUSTERING OFF THE 12Z
GFS/CMC/ECMWF AS THEY SIT IN THE CENTER OF THE SPREAD.


...PAIR OF EASTERLY WAVES AFFECTING EASTERN MEXICO AND
FL...RESPECTIVELY...

FINAL PREFERENCE: EASTERN MEXICO WAVE: NON-12Z NAM MODEL
COMPROMISE...FL WAVE: NON-12Z NAM/UKMET MODEL COMPROMISE
FORECAST CONFIDENCE: AVERAGE

TWO EASTERLY WAVES ARE FORECAST TO AFFECT THE BAY OF CAMPECHE AND
THE BAHAMAS...RESPECTIVELY. WITH REGARD TO THE SYSTEM APPROACHING
EASTERN MEXICO...THE 12Z NAM IS DEFINITELY THE MOST NORTHERN
SOLUTION WHICH WOULD BRING HEAVY RAINFALL INTO SOUTH TX ON DAY 3.
THE OTHER MODELS ARE CLOSE ENOUGH WITH THEIR MORE SOUTHERN
POSITIONS WITH LESS IMPACTS ACROSS THE LOWER 48. MEANWHILE...WITH
THE EASTERLY WAVE CROSSING THE BAHAMAS...THE 12Z NAM WAS QUICKER
BEING OFF TOWARD THE WEST WHILE THE 12Z UKMET DEPICTS A MORE
SUPPRESSED SOLUTION. THE 12Z GFS/ECMWF/CMC LEAN FAVORABLY TOWARD
CLUSTERED ENSEMBLE MEANS SO A NON-12Z NAM/UKMET PREFERENCE IS
RECOMMENDED.


www.wpc.ncep.noaa.gov/html/model2.shtml...
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

RUBIN-OSTER