Prognostic Meteorological Discussion
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000
FXUS10 KWNH 261632
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1232 PM EDT WED AUG 26 2015

VALID AUG 26/1200 UTC THRU AUG 30/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS


...WEAKENING CLOSED LOW TRACKING EAST ACROSS ONTARIO/QUEBEC
THROUGH THURS...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

NO SIGNIFICANT DIFFERENCES WERE NOTED WITH THIS SYSTEM.


...UPPER TROUGH/CLOSED LOW OVER THE CENTRAL/EASTERN GULF OF
MEXICO...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM IS AN OUTLIER WITH RESPECT TO THE REMAINING
DETERMINISTIC AND ENSEMBLE GUIDANCE IN DIGGING AN UPPER LOW MUCH
FARTHER SOUTHWEST ACROSS THE GULF OF MEXICO. THE NAM IS ALSO
OVERALL STRONGER THAN THE MULTI-MODEL CONSENSUS TOO. THERE IS GOOD
AGREEMENT IN AN NON-NAM CONSENSUS AND THIS WILL BE THE PREFERENCE.


...DEEP UPPER TROUGH OVER THE EASTERN PACIFIC...
...APPROACHING THE PACIFIC NORTHWEST FRI NIGHT...

PREFERENCE: NON-CMC CONSENSUS
CONFIDENCE: ABOVE AVERAGE

A DEEP UPPER TROUGH OFFSHORE THE WEST COAST WILL ADVANCE EAST AND
INLAND ACROSS THE PACIFIC NORTHWEST BY SAT IN RESPONSE TO
ADDITIONAL STRONG HEIGHT FALLS DIGGING SOUTH THROUGH THE GULF OF
AK AND TOWARD WESTERN BRITISH COLUMBIA FRI AND SAT. THE 00Z CMC
BECOMES THE SLOWEST SOLUTION TO ADVANCE THE ENERGY INLAND. THE
REMAINING MODELS ARE REASONABLY WELL CLUSTERED ON A MORE
PROGRESSIVE SOLUTION...AND SO A NON-CMC CONSENSUS WILL BE
PREFERRED.


...SHORTWAVE LIFTING NORTHEAST THROUGH THE GREAT BASIN...
...REACHING THE CENTRAL/NORTHERN PLAINS AND MIDWEST THURS AND
FRI...

PREFERENCE: BLEND OF THE 12Z NAM/12Z GFS AND 12Z UKMET
CONFIDENCE: BELOW AVERAGE

THE MODELS ARE IN VERY GOOD AGREEMENT IN EJECTING A SHORTWAVE
MOVING NORTH INTO SOUTHERN UT OFF TO THE NORTHEAST AROUND THE FOUR
CORNERS RIDGE AXIS AND OUT INTO THE NORTHERN AND CENTRAL PLAINS BY
LATE THURS...AND THEN INTO THE MIDWEST ON FRI. THE 00Z ECMWF IS A
STRONG OUTLIER WITH THE SYSTEM AS THE ENERGY APPROACHES THE
MIDWEST BY EARLY FRI THE ECMWF ALSO BECOMES THE DEEPEST SOLUTION
WITH ITS ATTENDANT SURFACE LOW. THE ECMWF ALSO BECOMES FARTHER
NORTH WITH THE TRACK OF VORT ENERGY AND THE SURFACE LOW WHICH IS
HAS CROSSING SOUTHERN WI ON SAT. THE 12Z GFS/00Z UKMET AND 00Z CMC
ARE THE WEAKEST SOLUTIONS...WITH THE 12Z NAM SOMEWHAT STRONGER AND
GENERALLY IN BETWEEN THE ECMWF AND GFS REGARDING DEPTH. THE
STRONGEST MODEL CLUSTERING AT THIS POINT WOULD TEND TO FAVOR THE
12Z GFS AND 00Z UKMET. HOWEVER...AS A MEANS OF ACCOUNTING FOR THE
SPREAD AND PROVIDING A HEDGE...WILL SUGGEST INCORPORATING SOME OF
THE RELATIVELY STRONGER 12Z NAM. THEREFORE...WILL FAVOR BLENDING
THE 12Z NAM/12Z GFS AND 00Z UKMET AT THIS POINT. CONFIDENCE IS
LIMITED GIVEN THE SPREAD...AND ESPECIALLY WITH THE GEFS MEAN
FAVORING THE WEAKER GFS-LED CONSENSUS...AND THE ECENS MEAN
FAVORING THE STRONGER ECMWF.


...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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