Prognostic Meteorological Discussion
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000
FXUS10 KWNH 240628
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
227 AM EDT THU JUL 24 2014

VALID JUL 24/0000 UTC THRU JUL 27/1200 UTC

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

...FINAL 00Z EVALUATION WITH PREFERENCES...

ANY INITIALIZATION ERRORS WITH THE 00Z NAM/GFS DO NOT SEEM
SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.

...DEEP UPPER LOW MOVING FROM THE PACIFIC NORTHWEST TO THE UPPER
MIDWEST VIA CENTRAL CANADA...

PREFERENCE: ECMWF
CONFIDENCE: AVERAGE

THE NAM HAS SLOWED CONSIDERABLY IN COMPARISON TO ITS 12Z RUN AND
IS NOW SLOWER THAN MOST OF THE GUIDANCE BY LATE FRI AS THE LOW IS
FORECAST TO DIP SOUTHEAST FROM SOUTHERN SASK TOWARD THE UPPER
MIDWEST.  IN CONTRAST...THE GFS IS FASTER THAN ITS 12Z RUN AND IS
ON THE LEADING EDGE OF THE MOST RECENT GUIDANCE.  THE 00Z
UKMET/ECMWF...WHICH HAVE SLOWED FROM THEIR 12Z RUNS...AND THE 00Z
CANADIAN GLOABL AND GEFS MEAN ARE ALL SLOWER THAN THE GFS.
RECOMMEND THE ECMWF WHICH IS CLOSEST TO THE MIDST OF THE SPREAD.


...SURFACE LOW TRACKING THROUGH THE GREAT PLAINS ON
THURSDAY/FRIDAY...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: AVERAGE

A SURFACE LOW IS FORECAST TO DEVELOP NEAR THE TAIL END OF THE
FRONT NOW MOVING ACROSS THE EASTERN U.S....DROPPING
EAST-SOUTHEASTWARD FROM THE LEE OF THE NORTHERN ROCKIES THROUGH
THE MO VALLEY INTO THE MID MS VALLEY BY SAT MORNING...WITH A MID
LEVEL IMPULSE MOVING ACROSS THE TOP OF THE CENTRAL U.S. RIDGE.
MODELS DO NOT PRESENT ANY LARGE SCALE DIFFERENCES...BUT DIFFER
WITH SOME OF THE MORE DIFFICULT TO PREDICT FINER DETAILS.

...MEAN UPPER TROF OVER NORTHEASTERN NORTH AMERICA...
...ASSOCIATED COLD FRONT...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: AVERAGE

WHILE THERE ARE SOME DETAIL DIFFERENCES WITH RESPECT TO THE
NUMEROUS SHORTWAVES FORECAST TO MOVE THROUGH THE BROADER SCALE
TROUGH...MODELS ARE OVERALL IN FAIRLY GOOD AGREEMENT WITH RESPECT
TO THE MOVEMENT OF THE TROUGH AND ITS ASSOCIATED COLD FRONT.

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

PEREIRA

$$





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