Prognostic Meteorological Discussion
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FXUS10 KWNH 230429
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1229 AM EDT THU MAR 23 2017

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

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

...PLEASE NOTE THAT THE NAM WAS UPGRADED TO A NEW VERSION 21/12Z
CYCLE...

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


...NORTHERN STREAM SHORTWAVE CROSSING SOUTH-CENTRAL CANADA THROUGH
THURS...
...CLOSED LOW DIVING THROUGH SOUTHEAST CANADA BY SAT MORNING...
...COLD FRONT ADVANCING DOWN ACROSS THE GREAT LAKES/NORTHEAST...

PREFERENCE: 00Z GFS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS CONTINUE TO SHOW GOOD AGREEMENT WITH RESPECT TO THE
STRONG HEIGHT FALLS/CLOSED LOW EVOLUTION DOWN INTO SOUTHEAST
CANADA THROUGH THE PERIOD. THIS WILL DRIVE A STRONG AREA OF UPPER
LEVEL CONFLUENCE OVER SOUTH-CENTRAL CANADA THROUGH FRI AND AREAS
JUST NORTH OF THE GREAT LAKES REGION AND NORTHEAST THROUGH SAT. A
COLD HIGH PRESSURE CENTER WILL TRAVERSE THIS REGION IN BEHIND A
COLD FRONT THAT WILL CROSS THE GREAT LAKES AND NORTHEAST THROUGH
THE PERIOD. THERE IS SOME MODEST SPREAD WITH THE TIMING OF THE
FRONT MOVING DOWN THROUGH THE NORTHEAST...WITH THE 12Z ECMWF
DRIVING THE COLD FRONT A BIT FARTHER SOUTH AND THE 12Z UKMET AND
00Z NAM A BIT SLOWER AND FARTHER NORTH. THE 00Z GFS SPLITS THE
DIFFERENCE AT THIS POINT AND REPRESENTS THE MODEL CONSENSUS. WILL
LEAN TOWARD THE GFS AT THIS TIME.


...STRONG UPPER TROUGH CROSSING THE SOUTHWEST/FOUR CORNERS THROUGH
THURS...
...CLOSED LOW EVOLUTION OVER THE CENTRAL PLAINS FRI...
...ENERGY CROSSING THE MID MS/OH VALLEYS THROUGH SAT...


PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 48 HOURS
            NON-NAM CONSENSUS...AFTER 48 HOURS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE GUIDANCE CONTINUES TO TAKE THE UPPER TROUGH DIGGING INTO THE
SOUTHWEST OFF TO THE EAST OVER THE NEXT SEVERAL DAYS...WITH THE
SYSTEM CROSSING THE FOUR CORNERS REGION ON THURS AND THEN EJECTING
OUT ACROSS THE CENTRAL PLAINS ON FRI WHERE AN AREA OF LOW PRESSURE
WILL DEEPEN. THIS LOW INITIALLY IN THE LEE OF THE CO ROCKIES WILL
REACH THE MID MS VALLEY BY MIDDAY SAT BEFORE THEN LIFTING NORTH OF
THE OH RIVER VALLEY BY EARLY SUN. THE 00Z NAM GENERALLY AFTER
ABOUT 48 HOURS IS TOO FAR SOUTH WITH ITS CLOSED LOW TRACK. THE
REMAINING MODELS ARE WELL CLUSTERED AND HAVE STRONG SUPPORT FROM
THE GEFS MEAN AND ECENS MEAN TOO...SO WILL PREFER A NON-NAM
CONSENSUS AFTER 48 HOURS...WITH A GENERAL MODEL COMPROMISE PRIOR
TO THIS.


...NORTHERN STREAM TROUGH/COLD FRONT REACHING THE NORTHWEST
THURS/FRI...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THERE ARE ONLY MINOR TIMING DIFFERENCES WITH THIS SYSTEM AND ITS
ASSOCIATED COLD FRONT...THUS A GENERAL MODEL COMPROMISE IS
PREFERRED TO SMOOTH OUT THESE SMALLER SCALE DIFFERENCES.


...SOUTHERN STREAM COMPONENT OF UPPER LEVEL TROUGH OVER THE WEST
ON SAT...

PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM BECOMES A TAD SLOWER/DEEPER THAN THE MODEL CONSENSUS
WITH THE SOUTHERN STREAM TROUGH COMING INTO WEST ON SAT AND
ESPECIALLY CA. THE REMAINING MODELS ARE WELL CLUSTERED WITH TIMING
AND DEPTH...SO A NON-NAM CONSENSUS WILL BE PREFERRED.


www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

$$





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