Prognostic Meteorological Discussion
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FXUS10 KWNH 231852
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 PM EDT WED APR 23 2014

VALID APR 23/1200 UTC THRU APR 27/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND ECMWF


...MID LEVEL TROUGH/CLOSED LOW IMPACTING NEW ENGLAND THROUGH
THURS...

PREFERENCE: GENERAL MODEL CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE LATEST MODELS ARE IN VERY GOOD AGREEMENT ON THE LARGE SCALE
WITH THE MID LVL TROUGH/CLOSED LOW IMPACTING THE NORTHEAST TODAY
THROUGH THURS. A GENERAL MODEL CONSENSUS WILL BE PREFERRED TO
RESOLVE ANY LINGERING SMALLER SCALE DIFFS.


...WESTERN U.S. TROUGH ADVANCING ACROSS THE MIDWEST/GREAT LAKES
THROUGH SAT...
...ATTENDANT SURFACE LOWS AND COLD FRONT MOVING INTO THE EASTERN
U.S...

PREFERENCE: 12Z ECMWF
CONFIDENCE: AVERAGE

THERE HAS BEEN GENERAL A TREND IN THE GUIDANCE TO BE SLIGHTLY
SLOWER AND A LITTLE FARTHER NORTH WITH A CLOSED MID LVL LOW CENTER
THAT FORMS NEAR THE U.S./CANADIAN BY THURS MORNING IN RELATION TO
THE MID LVL TROUGH EJECTING OUT OF THE NORTHWEST. THIS TRENDS
CAUSES THE COLD FRONT PROGRESSION TO BE A TAD SLOWER ADVANCING
THROUGH THE OH VLY AND TWD THE EAST COAST THURS THROUGH SAT. THE
MODELS SUPPORT ONE LOW CENTER NEAR THE U.S./CANADIAN BORDER
IMPACTING THE NRN PLAINS/UPR MIDWEST AND GRT LAKES REGION THROUGH
THE PERIOD...WHICH IS MORE TIED TO THE DYNAMICS OF THE
AFOREMENTIONED MID LVL CLOSED LOW. THE MODELS ALSO SUPPORT ANOTHER
LOW CENTER FARTHER SOUTH DEVELOPING ALONG THE FRONT OVER THE CNTRL
PLAINS AND MID MS VLY WHICH ADVANCES NEWD THROUGH THE PERIOD TWD
THE GRT LAKES REGION...AND EVENTUALLY MERGING WITH THE LOW CENTER
FARTHER NORTH AS THE SYS MOVES INTO THE NORTHEAST ON SAT. THE
SECOND LOW CENTER FARTHER SOUTH IS IN RELATION TO A SEPARATE
SHORTWAVE TROUGH ROUNDING THE BASE OF THE CLOSED LOW CENTER. THE
12Z UKMET/12Z GEM AND 12Z ECMWF ALL TRENDED A BIT STRONGER AND NOW
CLUSTER MORE STRONGLY TWD THE ALREADY STRONGER 12Z NAM/12Z GFS
CAMP AS IT RELATES TO THE EVOLUTION OF THE CLOSED MID LVL LOW
CENTER. THERE IS MUCH BETTER TIMING AGREEMENT TOO...HOWEVER THE
12Z GFS IS STILL THE STRONGEST SOLN OVERALL FOLLOWED CLOSELY BY
THE 12Z NAM AND BOTH THESE MODELS TEND TO FAVOR A STRONGER SFC LOW
IMPACTING THE GRT LAKES REGION AND THE NORTHEAST FRI/SAT. THE 12Z
GEFS MEAN IS STILL NOT AS A STRONG AS THE DETERMINISTIC GFS OR THE
NAM. HOWEVER...BASED ON THE LATEST TRENDS...A SOMEWHAT MORE ROBUST
SOLN WILL BE PREFERRED. ACCOUNTING FOR ALL THE MODELS...WILL
PREFER A SOLN TWD THE 12Z ECMWF.


...UPPER LEVEL TROUGHING AFFECTING THE WESTERN U.S. FROM THURS
THROUGH SAT...

PREFERENCE: 12Z GEFS MEAN/00Z ECENS MEAN COMPROMISE
CONFIDENCE: AVERAGE

ALL OF THE MODELS SHOW A STRONG DEEP LAYER TROUGH ADVANCING INTO
THE WRN U.S. FRI AND SAT...WITH ENERGY ATTEMPTING TO SEPARATE OUT
OVER THE FOUR CORNERS REGION BY LATE SAT. THE MODELS SHOW
REASONABLY GOOD AGREEMENT WITH THE TIMING OF THE HEIGHT
FALLS...ALTHOUGH BY LATE IN THE PERIOD...THE 12Z NAM IS SEEN AS
BEING A LITTLE QUICKER TO ADVANCE HEIGHT FALLS TWD THE CNTRL HIGH
PLAINS. THE 12Z NAM IS ALSO THE STRONGER MODEL OVERALL WITH THE
HEIGHT FALLS. THE 12Z GFS AND 12Z UKMET ARE A LITTLE SLOWER THAN
THE 12Z NAM...FOLLOWED BY THE 12Z ECMWF AND THE 12Z GEM WHICH IS
THE SLOWEST. THE 12Z GEFS MEAN IS A LITTLE SLOWER THAN THE 12Z
GFS...WITH THE 00Z ECENS MEAN A LITTLE FASTER THAN THE LATEST
ECMWF. ACCOUNTING THE OUTLIER SOLNS PER THE SLOW GEM AND FAST
NAM...A MIDDLE OF THE ROAD APPROACH LED BY THE ENSEMBLE MEANS
SHOULD SUFFICE. WILL PREFER A BLEND OF THE 12Z GEFS MEAN AND 00Z
ECENS MEAN.


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

ORRISON

$$





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