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 0649Z Oct 20, 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
249 AM EDT MON OCT 20 2014

VALID OCT 20/0000 UTC THRU OCT 23/1200 UTC

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

...AN EVALUATION OF ALL 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.


...NEGATIVELY-TILTED SHORTWAVE LIFTING UP COASTAL NEW ENGLAND...

FINAL PREFERENCE: GENERAL MODEL CONSENSUS
FORECAST CONFIDENCE: HIGH

A PROGRESSIVE SHORTWAVE EXITING THE VA CAPES EARLIER ON SUNDAY HAS
ATTAINED A NEGATIVE TILT WHILE LIFTING OFFSHORE OF COASTAL NEW
ENGLAND. THIS HAS ALLOWED A SURFACE LOW TO DEEPEN AS IT MOVES
TOWARD NEWFOUNDLAND EARLY MONDAY. WHILE THE SYSTEM IS STILL ACROSS
THE MAP DOMAIN...MODELS SHOW SUFFICIENT AGREEMENT TO WARRANT A
GENERAL MODEL CONSENSUS SOLUTION.


...CLIPPER-LIKE SYSTEM RACING THROUGH THE UPPER MIDWEST...
...UPPER LOW CLOSING OFF OVER THE MID-ATLANTIC
WEDNESDAY/THURSDAY...

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

THE HIGH AMPLITUDE FLOW SETTING IN THE NORTHERN STREAM WILL FAVOR
ABOVE NORMAL HEIGHTS IN THE CENTER OF THE COUNTRY WHILE A POTENT
SHORTWAVE DIVES THROUGH THE UPPER MIDWEST. THIS FEATURE IS WELL
IDENTIFIED ON WATER VAPOR IMAGERY AS IT RACES FROM THE MN/WI/IA
SOUTHEASTWARD TOWARD THE LOWER GREAT LAKES/UPPER OH VALLEY. BY
TUESDAY ONWARD...THE EASTWARD PROGRESSION NEARLY HALTS AS THE
SYSTEM BECOMES CUT-OFF FROM THE MAIN STEERING FLOW. THE 12Z ECMWF
ENSEMBLE MEMBERS SUPPORT A SLIGHTLY DEEPER SOLUTION ALOFT PER THE
NUMBER OF MEMBERS PLOTTED ON THE 552-DM SPAGHETTI PLOT. IT HAS
TRENDED STRONGER RELATIVE TO THE PAST DAY OF RUNS. COMPARING THIS
IDEA TO OTHER 00Z GUIDANCE...THE MODELS APPEAR TO HAVE TRENDED
SLOWER...PARTICULARLY THE 00Z ECMWF WHICH HAS COME CLOSER TO THE
SLOWER 00Z NAM. MEANWHILE...THE 00Z UKMET HAS MOVED IN THE
OPPOSITE DIRECTION BEING FARTHER NORTH WITH AN ACCOMPANYING
SURFACE LOW TRACK THAT IS CLOSER TO THE COAST AND MUCH DEEPER.
HAVE DECIDED TO LEAN SLOWER COMPARED TO THE PREVIOUS PREFERENCE
GIVEN THE TREND NOTED ALONG WITH THE FACT THE FORECAST INVOLVES A
SLOW-MOVING UPPER LOW.  THIS WOULD FAVOR A COMBINATION OF THE 00Z
NAM/ECMWF.


...CLOSED LOW GRADUALLY SHEARING OVER NORTHERN MX ON MONDAY
EVENING...

FINAL PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: ABOVE AVERAGE

AN UPPER LOW SPINNING OVER NORTHWESTERN MX HAS HELPED INVIGORATE
AN AREA OF RAINFALL OVER SOUTH-CENTRAL NM/FAR WEST TX WITHIN A
NARROW AXIS OF MOISTURE RETURN. THIS FEATURE WILL GRADUALLY LOSE
ITS IDENTITY OVER NORTH-CENTRAL MX AS IT BEGINS TO SHEAR LATE
MONDAY. MODELS VARY SLIGHTLY WITH HOW MUCH ENERGY REMAINS WHILE
CROSSING INTO CENTRAL TX ON TUESDAY. WILL FAVOR A GENERAL MODEL
COMPROMISE GIVEN THE SPREAD REMAINS ON THE LOW SIDE.


...AMPLIFIED TROF REACHING THE WEST COAST BY 20/1800Z...
...EVENTUAL SPLIT FLOW ACROSS THE GREAT PLAINS BY MID-WEEK...

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

A SINUSOIDAL PATTERN IS IN PLACE ACROSS THE MID-LATITUDES WITH
HEIGHTS BUILDING IN THE CENTER OF THE COUNTRY. MEANWHILE...AN
AMPLIFIED TROF WILL APPROACH THE WEST COAST AND ADVANCE INLAND BY
MONDAY AFTERNOON/EVENING. THE KEY FEATURE IN THIS PATTERN IS A
SHORTWAVE CROSSING INTO NORTHERN CA BY MONDAY NIGHT. THE 00Z
NAM/CMC ARE SLOWER EARLY IN THE PERIOD...PARTICULARLY THE 00Z NAM
AS IT CARRIES ENERGY INTO WEST-CENTRAL NV WHILE OTHER GUIDANCE ARE
UP CLOSER TO THE OR/ID BORDER. IT DOES APPEAR SOME OF THE GUIDANCE
HAS TRENDED SLOWER AS THE 00Z ECMWF/UKMET ARE WEST OF THEIR
PREVIOUS SOLUTIONS AT 21/1200Z. MODEL SPREAD GROW BY EARLY
WEDNESDAY ONWARD AS THE UPPER FLOW BEGINS TO SPLIT OVER THE HIGH
PLAINS. IT SEEMS THE LATEST GUIDANCE DO AT LEAST LOOK MORE SIMILAR
TO ONE ANOTHER THAN THE PREVIOUS MODEL CYCLE. THE 00Z CMC NO
LONGER OVEREMPHASIZES THE SOUTHERN BRANCH OF THE SPLIT TO GO WITH
THE FACT THE 00Z ECMWF HAS SLOWED WITH THE SYSTEM LIFTING INTO
CENTRAL CANADA. THE 00Z ECMWF SOLUTION HAS STARTED TO LOOK MORE
LIKE THE 00Z GFS WHICH DEPICTS A MORE ROBUST NORTHERN STREAM
FEATURE. MEANWHILE...THE 00Z UKMET NOW ADVERTISES A MORE
SIGNIFICANT SPLIT BETWEEN THE TWO STREAMS. GIVEN THE AMOUNT OF
VARIABILITY IN EACH OF THE DETERMINISTIC RUNS...CONFIDENCE WILL
REMAIN BELOW AVERAGE. WILL GO AHEAD AND COMBINE THE SOLUTIONS OF
THE 00Z GFS/ECMWF GIVEN THIS APPEARS TO BE THE LATEST TREND.


...LONGWAVE TROF ANCHORING THE NORTHEASTERN PACIFIC TUESDAY
THROUGH THURSDAY...

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

BROAD CYCLONIC FLOW OVER THE NORTHEASTERN PACIFIC WILL ALLOW A
MYRIAD OF SHORTWAVES TO RACE TOWARD THE PACIFIC NORTHWEST AND
BRITISH COLUMBIA. THE LOW-AMPLITUDE/PROGRESSIVE FLOW IS
CHARACTERIZED BY BUILDING SPREAD GIVEN THE UNCERTAINTIES IN THIS
FLOW REGIME. THE ENSEMBLE MEANS APPEAR TO AT LEAST HAVE A HANDLE
ON THE SYNOPTIC-SCALE PATTERN SO WILL LEAN ON THEIR OUTPUT WITH
THIS ISSUANCE. UNFORTUNATELY THE ENSEMBLE MEANS SHOW MORE
VARIABILITY THAN PREVIOUSLY SO THE CONFIDENCE WILL BE REDUCED.


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

RUBIN-OSTER