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 0643Z Nov 25, 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
143 AM EST TUE NOV 25 2014

VALID NOV 25/0000 UTC THRU NOV 28/1200 UTC

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

00Z NAM/GFS EVALUATION INCLUDING THE UKMET/CANADIAN/ECMWF AND
PREFERENCES

...SHORTWAVE TROUGH/LOW PRESSURE TRACKING FROM THE N. PLAINS TO
THE APPALACHIANS TODAY THROUGH WED...

PREFERENCE: 1/2 EACH NAM/GFS
CONFIDENCE: ABOVE AVERAGE

THE NAM AND GFS HAVE TRENDED FASTER AND STRONGER FROM PREVIOUS
RUNS AND HAVE GOOD SUPPORT FROM THE UKMET/CANADIAN...ALL OF WHICH
ARE FASTER AND MORE AMPLIFIED THAN THE ECMWF ENTERING THE OH/TN
VALLEYS.  GIVEN THIS AGREEMENT...RECOMMEND A BLEND OF THE
NAM/GFS...WHICH ALSO ADDRESSES ANY LINGERING UNCERTAINTY.

...LOW PRESSURE TRACKING UP THE EAST COAST TONIGHT THROUGH WED
NIGHT...

PREFERENCE: 1/4 EACH NAM/ECMWF/12Z ECMWF ENSEMBLE MEAN/21Z SREF
MEAN
CONFIDENCE: AVERAGE

CHANGES IN THE LARGE-SCALE DEPICTIONS OF THE 00Z NAM AND GFS
COMPARED TO THEIR 18Z RUNS IS RELATIVELY SMALL...WITH A GENERAL
BUT SMALL TREND TOWARD FASTER NORTHWARD MOVEMENT UP THE COAST. 
THUS...THE LARGE-SCALE PREFERENCES FROM THE DURING THE DAY ON
MONDAY ARE STILL RELEVANT.  THE ONLY CHANGE IS TO ADD THE NAM AND
ECMWF TO THE PREFERENCES SINCE THEY SETTLE MORE CLOSELY TO THE
MIDDLE OF THE SOLUTION ENVELOPE FOR THE LOW TRACK AND DEPTH.  THE
GFS LIES TOWARD THE NORTHEAST SIDE OF THE GUIDANCE.

ONE NOTE ABOUT THE NAM WORTH FORWARDING IS THAT FROM 00-12Z
WED...THE NAM APPEARS TO SUFFER FROM GRID-SCALE FEEDBACK OVER THE
SOUTHERN APPALACHIANS...WHICH ULTIMATELY RESOLVES ITSELF. 
HOWEVER...ITS RESULTING THERMAL PROFILES AND QPF OVER THE SOUTHERN
APPALACHIANS MAY BE UNRELIABLE.  THIS OBSERVATION IS SUPPORTED BY
THE NAM CONUSNEST WHICH SHOWS NO PRECIPITATION DEVELOPING.

REGARDING LOWER LEVEL THERMAL PROFILES WEST OF THE LOW...THE NAM
AND ECMWF MAY BE MORE USABLE THAN THE GFS SINCE THE GFS LIES
TOWARD THE NORTHEASTERN SIDE OF THE GUIDANCE WITH ITS LOW TRACK
AND MAY PRODUCE DECOUPLED FLOW INLAND TOO SOON AND FOR TOO LONG. 
ANOTHER FACTOR WHICH INTRODUCES SOME UNCERTAINTY REGARDING
TEMPERATURES IS THE RECENT WARM PERIOD AND RESULTING WARM GROUND
THAT COULD RADIATE SUFFICIENTLY WARM AIR TO COUPLE WITH THE FLOW
JUST ABOVE THE SURFACE.  THE NAM AND ECMWF AT TIMES FORECAST 925
MB FLOW OF 30 TO 50 KNOTS....WHICH COULD EASILY COUPLE WITH THE
WINDS NEAR THE SURFACE AND PRODUCE A SUFFICIENTLY DEEP MIXED LAYER
HELPING TO KEEP THE AIR NEAR THE GROUND WARMER THAN DEPICTED BY
GUIDANCE.  MODELS USUALLY HAVE A VERY DIFFICULT TIME RESOLVING THE
BOUNDARY LAYER STRUCTURE.   

...SHORTWAVE TROUGH BEGINNING TO INFLUENCE THE PACIFIC NORTHWEST
THURSDAY...

PREFERENCE: GFS OR ECMWF
CONFIDENCE: HIGH

THE NAM IS NEARLY AN OUTLIER WITH ALLOWING A LARGE PORTION OF THIS
TROUGH TO BEGIN MOVING ASHORE BY EARLY THURSDAY.  THE PRIMARY
RESULT EARLY IN THE DAY IS TO BUILD THE SHORTWAVE RIDGE AND SHIFT
THE MOST FAVORABLE CONDITIONS FOR ASCENT FARTHER NORTH.  GIVEN A
LACK OF SUPPORT FOR THIS SOLUTION...THE RECOMMENDATION IS FOR THE
GFS OR ECMWF.

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

JAMES