Prognostic Meteorological Discussion
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409
FXUS10 KWNH 230409
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MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1208 AM EDT SAT JUL 23 2016

VALID JUL 23/0000 UTC THRU JUL 26/1200 UTC

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

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


...AMPLIFIED FLOW ACROSS NEW ENGLAND/ASSOCIATED FRONTAL PASSAGE ON
SATURDAY...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

A SHORTWAVE TROUGH WILL BE DIGGING ACROSS THE LOWER GREAT LAKES
AND INTO THE NORTHEAST ON SAT ALONG WITH A COLD FRONT. THE 00Z NAM
AGAIN INSISTS ON A STRONGER SHORTWAVE AND MORE AMPLIFICATION OVER
THE NORTHEAST GOING THROUGH SUN. THE GLOBAL MODELS ARE NOT AS
STRONG AS THE NAM...AND SO A NON-NAM CONSENSUS WILL BE PREFERRED.


...CLOSED UPPER LOW RETROGRADING TOWARD THE FL PENINSULA THROUGH
SUNDAY...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

AN UPPER TROUGH AND ASSOCIATED CLOSED LOW EAST OF THE CAROLINAS
WILL DROP GRADUALLY SOUTH AND EVENTUALLY WILL TURN TO THE
SOUTHWEST TOWARD THE FL PENINSULA THROUGH SAT AND SUN. STRONGER
RIDGING BUILDING NORTH OF THE CLOSED LOW WILL ALLOW FOR IT TO THEN
TURN WEST BY MON AND TUES ACROSS THE GULF OF MEXICO. THE 00Z NAM
HANGS ONTO A STRONGER SYSTEM THROUGH THE PERIOD...WILL BE
DISCOUNTED IN FAVOR OF THE STRONG GLOBAL MODEL AGREEMENT WHICH IS
A TAD WEAKER.


...SHORTWAVE TROUGH FROM THE PACIFIC NORTHWEST ACROSS SOUTHERN
CANADA...
...QUICK-MOVING COLD FRONT CROSSING THE NORTHERN TIER STATES...

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

A WELL-DEFINED SHORTWAVE CURRENTLY EXITING THE PACIFIC NORTHWEST
WILL QUICKLY RACE EASTWARD REACHING THE SASKATCHEWAN/MANITOBA
BORDER LATE SAT. THE PATTERN IS WELL AGREED UPON AS A PAIR OF
SURFACE LOWS MOVE THROUGH THE U.S./CANADIAN GREAT PLAINS THIS
WEEKEND AND A COLD FRONT CROSSES THE NORTHERN TIER STATES. THE 00Z
NAM AND 12Z UKMET BOTH ARE A LITTLE FASTER TO EJECT THEIR HEIGHT
FALLS DOWNSTREAM ACROSS SOUTHERN CANADA...AND THIS LEADS TO A
SOMEWHAT MORE PROGRESSIVE SURFACE LOW REFLECTION. STRONGER MODEL
CLUSTERING AND ENSEMBLE SUPPORT LIES WITH THE 00Z GFS AND 12Z
ECMWF...AND SO A BLEND OF THESE SOLUTIONS WILL BE PREFERRED...AND
THESE SOLUTIONS ARE A LITTLE SLOWER THAN THE NAM/UKMET CAMP.


...RESIDUAL TROUGHING OVER THE CENTRAL GREAT BASIN LATE IN THE
PERIOD...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

IN THE WAKE OF THE SYSTEM TRACKING ACROSS SOUTHERN CANADA...A
BROAD BUT WEAK TROUGH LINGERS ACROSS THE CENTRAL GREAT BASIN.
THERE ARE SOME SMALL SCALE DIFFERENCES AMONG THE SOLUTIONS BUT
SUFFICIENT LARGE SCALE AGREEMENT EXISTS FOR A GENERAL MODEL
COMPROMISE TO BE PREFERRED.

ORRISON

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

$$





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