Prognostic Meteorological Discussion
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000
FXUS10 KWNH 070408
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1208 AM EDT TUE JUL 07 2015

VALID JUL 07/0000 UTC THRU JUL 10/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS

...SHORTWAVE TROUGH CLIPPING THE GREAT LAKES/NORTHERN NEW
ENGLAND...
...SURFACE WAVE DEVELOPING ALONG THE ATTENDANT FRONT OVER THE OH
VALLEY...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS TAKE THE SOUTHERN PORTION OF A NORTHERN STREAM
SHORTWAVE TROUGH ACROSS THE GREAT LAKES AND NORTHERN NEW ENGLAND
THROUGH TUES AND WED. AN ASSOCIATED COLD FRONT WILL CROSS THESE
AREAS AS WELL...BUT THE TAIL END OF THE FRONT SHOULD STALL OUT
OVER THE OH VALLEY AS A WAVE OF LOW PRESSURE DEVELOPS AND MOVES
EAST ALONG IT. THIS WAVE WILL EXIT THE MID-ATLANTIC REGION ON
THURS. THE 00Z NAM GRADUALLY BECOMES A TAD SLOW WITH THE SHORTWAVE
TROUGH EVOLUTION AS IT REACHES NORTHERN NEW ENGLAND...WITH THE
REMAINING MODELS WELL CLUSTERED. AT THE SURFACE...THERE IS
REASONABLY GOOD AGREEMENT WITH THE SURFACE LOW
EVOLUTION...ALTHOUGH THE 00Z NAM BECOMES A BIT DEEPER THAN THE
MULTI-MODEL CONSENSUS AS THE WAVE MOVES OFFSHORE ON THURS. A
NON-NAM CONSENSUS WILL BE PREFERRED.


...SHORTWAVE TROUGH SHEARING ACROSS THE CENTRAL
APPALACHIANS/MID-ATLANTIC THROUGH TUES...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW VERY GOOD AGREEMENT HERE AT THIS POINT...AND SO A
GENERAL MODEL COMPROMISE WILL BE PREFERRED AS THIS SYSTEM SHEARS
OUT THROUGH TUES.


...SHORTWAVE CROSSING THE SOUTHWEST AND CENTRAL/SOUTHERN PLAINS...
...DEVELOPING SURFACE LOW LIFTING THROUGH THE MID MS/OH VALLEYS...

PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

A MID LEVEL SHORTWAVE EMBEDDED WITHIN THE SOUTHWEST FLOW AHEAD OF
THE APPROACHING WEST COAST UPPER LOW IS FORECAST TO ADVANCE EAST
OUT INTO THE CENTRAL AND SOUTHERN HIGH PLAINS TUES AND WED AND
AMPLIFY SOMEWHAT. THIS WILL ALSO DEVELOP AND AREA OF LOW PRESSURE
NORTH OF THE RED RIVER VALLEY THAT WILL ADVANCE NORTHEAST TOWARD
THE MIDWEST BY WED AND THEN SHEAR EASTWARD ACROSS THE OH VALLEY ON
THURS. THE 00Z NAM IS THE STRONGEST SOLUTION OVERALL SURFACE AND
ALOFT. THE 12Z CMC WAS SEEN AS BEING PERHAPS A TAD SLOW WITH THE
SURFACE WAVE EVOLUTION. THE STRONGER MODEL CLUSTERING FAVORS A
BLEND OF THE 00Z GFS AND 12Z ECMWF...AND THAT WILL BE THE
PREFERENCE.


...EASTERN PACIFIC UPPER LOW HOVERING WEST OF CALIFORNIA...

PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 72 HOURS
            BLEND OF THE 00Z GFS AND 12Z ECMWF...AFTER 72 HOURS
CONFERENCE: ABOVE AVERAGE

ALL OF THE LATEST DETERMINISTIC GUIDANCE TAKES AN UPPER LOW OVER
THE EASTERN PACIFIC CURRENTLY CENTERED NEAR 357 130W SLOWLY
EASTWARD INTO CALIFORNIA LATE WED AND THURS. THE UPPER LOW IS THEN
EXPECTED TO OPEN UP INTO A LARGER SCALE UPPER TROUGH THAT WILL
MOVE INTO THE INTERMOUNTAIN WEST BY FRI IN RESPONSE TO ADDITIONAL
UPSTREAM HEIGHT FALLS APPROACHING THE WEST COAST. THERE IS VERY
GOOD MASS FIELD AGREEMENT THROUGH ABOUT 72 HOURS...BUT THEREAFTER
THE 12Z CMC BECOMES A BIT MORE PROGRESSIVE WITH THE UPPER TROUGH.
THE 12Z UKMET BECOMES A LITTLE SLOWER. THE 00Z GFS/00Z NAM AND 12Z
ECMWF ARE CLUSTERED IN BETTER AGREEMENT IN BETWEEN THE UKMET/CMC
SOLUTIONS BY THE END OF THE PERIOD. A GENERAL MODEL COMPROMISE
WOULD SUFFICE THROUGH ABOUT 72 HOURS AND THEN A BLEND OF THE
GFS/NAM AND ECMWF THEREAFTER.


...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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