Prognostic Meteorological Discussion
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000
FXUS10 KWNH 111640
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1239 PM EDT FRI JUL 11 2014

VALID JUL 11/1200 UTC THRU JUL 15/0000 UTC

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

==================================================
12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES
==================================================
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
==================================================

...DEEP CYCLONE AFFECTING THE CENTRAL AND NORTHERN U.S...

PREFERENCE: BLEND OF 06Z GFS WITH 00Z ECMWF/CANADIAN

THIS SYSTEM WILL DIG OVER THE MIDWEST AND GREAT LAKES THROUGH
MONDAY...WHILE LEAD SHORTWAVE SPREAD HEIGHT FALLS TO NEW ENGLAND
AND THE MID ATLANTIC...AND SURFACE HIGH PRESSURE BUILDS SOUTH
THROUGH THE PLAINS. REGARDING 850 MB TEMPERATURES AND 500 MB
HEIGHTS...AND RELATIVE TO CLIMATOLOGY...STANDARD DEVIATIONS ARE
LIKELY TO REACH 2 TO 3 WITHIN THE RIDGE OVER WESTERN NORTH AMERICA
AND MINUS 2 TO MINUS 3 WITHIN THE DOWNSTREAM TROUGH IN THE
NORTHERN U.S.

THE 12Z GFS JUMPED TOWARD A SOLUTION THAT IS QUITE A BIT FASTER
AND NOT AS DEEP. THE SLOWER AND DEEPER ECMWF/CANADIAN SOLUTIONS
HAD BEEN PREFERRED...BUT WE ALSO NOTE THAT THOSE SOLUTIONS FALL
TOWARD THE DEEP EDGE OF THE RELATIVELY NARROW SPREAD FOR THIS
SYSTEM. WITHOUT ANY STRONG EVIDENCE FOR A PARTICULARLY ROBUST
SYSTEM...GIVEN THE TIME OF YEAR AND HIGH SUN ANGLE OVER THE COLD
AIR SOURCE REGION...WE SUGGEST BLENDING THE DEEP ECMWF/CMC
SOLUTIONS TOWARD SOMETHING A BIT MORE TAME. THE 06Z GFS SEEMS A
VIABLE OPTION...AS IT FELL IN LINE WITH THE GEFS MEAN AND ECMWF
ENSEMBLE MEAN. AT THE SURFACE THE 06Z GFS MAY BE SLIGHTLY SLOW TO
DROP THE EFFECTIVE FRONTAL BOUNDARY THROUGH THE PLAINS.

THE 12Z NAM LOOKS GOOD THROUGH DAY 3...AND COULD VERY NEARLY BE
INCLUDED IN OUR DAY 1-3 PREFERENCE...BUT IT DOES JUMP SLIGHTLY
AHEAD OF CONSENSUS LATE IN THE PERIOD.


...SYSTEM MOVING INTO THE PACIFIC NORTHWEST...

PREFERENCE: BLEND OF THE OPERATIONAL MODELS...EXCLUDING THE 12Z NAM

THE GLOBAL MODELS ARE NOW HANDLING THIS SHORTWAVE TROUGH
SIMILARLY. THE 12Z NAM PRODUCED A UNIQUE SOLUTION BY SPLITTING THE
ENERGY WITHIN THE BASE OF THIS SMALL FEATURE AND LEAVING A
CYCLONIC MID LEVEL CIRCULATION EMBEDDED WITHIN RIDGING NEAR THE
CA/OR COAST. SUCH AN OCCURRENCE WOULD NOT BE IMPOSSIBLE GIVEN
POTENTIALLY WEAK INTERACTION BETWEEN THIS TROUGH AND THE
WESTERLIES...BUT THERE IS LITTLE MODEL SUPPORT AT THE CURRENT
TIME. SREF CLUSTERS LEND MORE SUPPORT TO THE GLOBAL MODEL
CONSENSUS IN THIS CASE.


...WESTWARD MOVING INVERTED TROUGH INFLUENCING THE SOUTHWEST U.S...

PREFERENCE: BLEND OF THE OPERATIONAL MODELS

THE GUIDANCE IS IN GOOD AGREEMENT WITH THIS SYSTEM MOVING WEST
NEAR THE U.S./MEXICO BORDER.  WE HAVE NO STRONG PREFERENCE FOR ANY
PARTICULAR MODEL SOLUTIONS...WITH ABOVE AVERAGE CONFIDENCE
CONSIDERING THE MINIMAL MODEL SPREAD.

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

BURKE
$$





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