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
245 PM EDT TUE OCT 21 2014

VALID OCT 21/1200 UTC THRU OCT 25/0000 UTC

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

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


WEAKENING MID-LEVEL TROUGH OVER NM TODAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW SIMILARLY WITH THIS FEATURE.


COASTAL STORM AFFECTING THE NORTHEASTERN U.S. THROUGH FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/ECMWF
CONFIDENCE: A BIT ABOVE AVERAGE

THE 12Z GFS AND 12Z ECMWF CONTINUE TO REPRESENT A GOOD COMPROMISE
WITH EXCELLENT RUN TO RUN CONTINUITY REGARDING THE 500 MB TROUGH
AND LOWER LEVEL LOW POSITIONS. THE ENSEMBLE MEANS AGREE WITH A
GFS/ECMWF BLEND WITH THE 12Z NAM/UKMET/CMC STRAYING AT VARIOUS
TIMES OF THE FORECAST THROUGH FRI EVENING.


MID-UPPER LEVEL TROUGH REACHING THE NRN PLAINS ON WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS...12Z ECMWF
CONFIDENCE: BELOW AVERAGE

MODEL CONSISTENCY CONTINUES TO BE POOR WITH THIS FEATURE...BUT THE
12Z GFS/ECMWF/UKMET/CMC SHOW REASONABLE AGREEMENT THROUGH THU
MORNING WITH REASONABLE RUN TO RUN CONSISTENCY. DIFFERENCES ARE
GREATEST FOR DAY 3...00Z 24-25...WITH THE 12Z UKMET/ECMWF/CMC
HAVING A MORE SRN TRACK WITH THE VORT CENTER AS IT CROSSES THE
UPPER MIDWEST THU NIGHT...WHICH CAUSES THE ENERGY TO TRACK FARTHER
SOUTH IN A MORE CONSOLIDATED MANNER VERSUS THE NAM/GFS WHICH IS
FARTHER NORTH. THE 12Z CAME IN SLIGHTLY ADJUSTED TOWARD THE GFS
BUT THE 12Z CMC ADJUSTED AWAY FROM THE GFS COMPARED TO THEIR 00Z
RUNS. AT THIS TIME...THE 12Z GFS AND 12Z ECMWF APPEAR TO SPLIT THE
DIFFERENCE IN TRACK AND ARE IN BETTER AGREEMENT WITH 00Z/21
ENSEMBLE SPAGHETTI HEIGHT PLOTS AT 500 MB...WITH THE 12Z UKMET AN
OUTLIER.


WEST COAST UPPER TROUGHING THROUGH FRI EVENING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/ECMWF/CMC
CONFIDENCE: AVERAGE

MODEL DIFFERENCES HERE ARE GREATEST THU NIGHT INTO FRI WITH THE
APPROACH OF A SHARPENING UPPER LEVEL TROUGH APPROACHING THE WEST
COAST. THE ENSEMBLE MEANS ARE IN PRETTY GOOD AGREEMENT WITH THE
DEPTH/TIMING OF THE UPPER TROUGH...WITH THE CLOSEST DETERMINISTIC
GUIDANCE BEING THE 12Z GFS/ECMWF/CMC. THE 12Z NAM IS
SLOWER...WHILE THE 12Z UKMET REMAINING FASTER.


QUASISTATIONARY FRONT NEAR SOUTH FLORIDA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z CMC BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THERE ARE MINOR LATITUDINAL DIFFERENCES WITH THE SWRN PORTION OF A
COLD FRONT TRANSLATING EWD ACROSS THE WRN ATLANTIC...WITH THE
BOUNDARY LYING ACROSS THE SRN PORTION OR JUST SOUTH OF THE FLORIDA
PENINSULA FOR THU/FRI. THERE IS NO CLEAR PREFERRED MODEL WITH THE
POSITION OF THE FRONT WITH THE LATEST DETERMINISTIC GUIDANCE
FORMING A REASONABLE COMPROMISE.

HOWEVER...REGARDING A POTENTIAL LOW OR TWO FORECAST TO DEVELOP
ALONG OR NEAR THE FRONT...THE 12Z CMC IS THE ONLY MODEL WHICH IS
NOT SUPPORTED BY THE REMAINING DETERMINISTIC GUIDANCE NOR THE
ENSEMBLES. CONFIDENCE IS REDUCED GIVEN THE CONVECTIVE/TROPICAL
NATURE OF THE ENVIRONMENT AND MODEST SPREAD IN THE LATEST ENSEMBLE
GUIDANCE.



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

OTTO





Last Updated: 245 PM EDT TUE OCT 21 2014