Prognostic Meteorological Discussion
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000
FXUS10 KWNH 260705
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 AM EDT TUE AUG 26 2014

VALID AUG 26/0000 UTC THRU AUG 29/1200 UTC

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


00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND THE
ECMWF


...UPPER LOW EXITING THROUGH SOUTHERN CANADA THROUGH TUES...
...TRAILING COLD FRONT...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE AGAIN SHOWS VERY GOOD AGREEMENT WITH THE DEPARTURE OF
THE UPPER LOW AND ASSOCD SFC LOW INTO CANADA THROUGH TUES MORNING.
THERE IS MINIMAL SPREAD TOO WITH THE TRAILING COLD FRONT THAT
CROSSES THE GREAT LAKES REGION AND MOVES INTO THE NORTHEAST TUES
NIGHT AND WED. A GENERAL MODEL COMPROMISE WILL AGAIN BE PREFERRED.


...MID LEVEL SHORTWAVE/CLOSED LOW DIGGING ADVANCING ACROSS THE
WEST...
...WEAK SURFACE LOW OVER THE CENTRAL PLAINS/MIDWEST BY FRI...

PREFERENCE: 00Z ECMWF
CONFIDENCE: AVERAGE

THE MODELS REMAIN IN VERY GOOD AGREEMENT AT LEAST ON THE LARGE
SCALE IN ALLOWING AN UPR TROUGH AND ASSOCD CLOSED LOW TO ADVANCE
EAST THROUGH THE GRT BASIN AND THEN CROSS THE CNTRL ROCKIES ON ITS
WAY OUT INTO THE PLAINS THROUGH THURS AND FRI. SOME DIFFS SHOW UP
BY THURS AND INTO FRI AS THE 00Z NAM AND 00Z GEM CONCENTRATE A
LITTLE MORE ENERGY/HEIGHT FALLS FARTHER NORTH AS COMPARED TO THE
00Z ECMWF/00Z GFS AND 00Z UKMET. THE 00Z ECMWF AND 00Z GFS BOTH
HAVE A CLOSED LOW NEAR THE CO/KS BORDER. THE 00Z NAM AND ESP THE
00Z GEM WITH THEIR ENERGY A LITTLE FARTHER NORTH ALSO SEND A WEAK
SFC LOW FARTHER OFF TO THE NORTHEAST UNTIL LATE IN THE PERIOD WHEN
THE 00Z GFS ARRIVES HERE AS WELL. THE 00Z ECMWF IS A BIT SLOWER.
THE 00Z UKMET SOLN APPEARS TOO DEEP AT THE SFC. THE ONE CONCERN AT
THE SFC WITH THE GFS IS SOME CONVECTIVE FEEDBACK...AND SO THE GFS
WILL NOT BE PREFERRED. BASED ON BETTER MODEL CONTINUITY WILL
PREFER THE 00Z ECMWF.


...EASTERLY WAVE ADVANCING WEST ALONG THE GULF COAST...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

SAT IMAGERY SHOWS A FAIRLY WELL-DEFINED EASTERLY WAVE ADVANCING
WWD ALONG THE GULF COAST...AND THE LATEST MODEL GUIDANCE SHOWS
THIS ENERGY ADVANCING WWD INTO SERN TX BY EARLY WED.
THEREAFTER...IT SHOULD SLOW CONSIDERABLY AND DRIFT SLOWLY NWD OUT
AHEAD OF THE EJECTING CNTRL ROCKIES/HIGH PLAINS TROUGH/CLOSED LOW
FEATURE. GIVEN RATHER GOOD AGREEMENT ON THE LARGE SCALE...WILL
PREFER A GENERAL MODEL COMPROMISE TO RESOLVE ANY SMALLER SCALE
DETAILS.


...SHORTWAVE TROUGH DIGGING INTO THE NORTHEAST THROUGH THURS AND
FRI...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

A NORTHERN STREAM TROUGH IS EXPECTED TO DIG ACROSS THE ST LAWRENCE
RIVER VLY ON WED AND INTO THE NORTHEAST ON THURS. THE MODELS ARE
WELL CLUSTERED WITH THE TIMING AND DEPTH OF THIS ENERGY...WITH
EXCEPTION OF THE 00Z NAM WHICH AGAIN IS A SLOWER AND DEEPER
OUTLIER SOLN. WILL BE FAVORING A NON-NAM CONSENSUS AS A RESULT.


...NORTHERN STREAM TROUGH CLIPPING THE U.S./CANADIAN BORDER BY
FRI...

PREFERENCE: 00Z ECMWF
CONFIDENCE: ABOVE AVERAGE

A NRN STREAM TROUGH WILL BE CLIPPING THE NRN TIER STATES THURS
INTO FRI. THE 00Z GFS IS A TAD SLOWER WITH THIS ENERGY...AND ESP
ITS SFC LOW REFLECTION HERE. THE 00Z UKMET IS THE MOST PROGRESSIVE
SOLN...WITH THE REMAINING MODELS SPLITTING THE DIFF. THE 00Z GEM
IS THE DEEPEST SOLN. WILL BE PREFERRING THE 12Z ECMWF.


...DEEP TROUGH DIGGING JUST OFF THE NORTHWEST BY FRI...

PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z NAM AND 00Z GEM ARE A TAD STRONGER THAN THE GLOBAL MODEL
CONSENSUS WITH THE UPR TROUGH DIGGING THROUGH THE GULF OF AK AND
OFFSHORE THE NORTHWEST THURS AND FRI. THE GLOBAL MODELS ARE
REASONABLY WELL CLUSTERED OTHERWISE...WITH THE 00Z GFS AND THE 00Z
ECMWF MORE STRONGLY ALIGNED. WILL PREFER A BLEND OF THE GFS AND
ECMWF ATTM.

...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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