176
FXUS10 KWNH 010646
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
145 AM EST SUN DEC 01 2019
VALID DEC 01/0000 UTC THRU DEC 04/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEP CLOSED LOW CROSSING THE INTERMOUNTAIN WEST/PLAINS
..SYSTEM REACHING THE MID-ATLANTIC/NEW ENGLAND BY MON/TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND...THROUGH 48 HOURS
00Z GFS/12Z ECMWF/12Z ECENS BLEND...AFTER 48 HOURS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE DEEP LAYERED CLOSED LOW CROSSING THE MIDWEST WILL ADVANCE
STEADILY EAST ACROSS THE OH VALLEY ON SUNDAY AND REACH THE
MID-ATLANTIC REGION BY MONDAY. THE ATTENDANT AREA OF LOW PRESSURE
WILL LIFT ACROSS THE UPPER OH VALLEY AND THE LOWER GREAT LAKES
REGION, WITH SECONDARY CYCLOPEDIAS OCCURRING NEAR THE DELMARVA BY
LATE SUNDAY WHICH WILL THEN LIFT NORTHEAST AND DEEPEN NEAR
SOUTHEAST NEW ENGLAND THROUGH MONDAY. BY TUESDAY, THE SYSTEM
SHOULD EXIT ACROSS THE GULF OF MAINE AND REACH CANADIAN MARITIMES.
THE GUIDANCE IS IN RATHER GOOD AGREEMENT THROUGH ABOUT 48 HOURS,
BUT THEREAFTER, THE 00Z GFS TENDS TO FOCUS IS LOW PRESSURE A
LITTLE FARTHER OFFSHORE OF NEW ENGLAND COMPARED TO THE 00Z NAM,
00Z UKMET AND ESPECIALLY THE 00Z ECMWF. THE ECMWF ACTUALLY TRENDED
A BIT FARTHER WEST AS THE SYSTEM ARRIVES UP ACROSS THE GULF OF
MAINE. THE 12Z CMC MEANWHILE IS BIT FARTHER OFFSHORE AS WELL, AND
ACTUALLY IS GENERALLY EAST OF THE GFS. BASED ON THE LATEST TRENDS
AND CLUSTERING, IT WOULD APPEAR THAT THE ECMWF MY BE A LITTLE TOO
FAR WEST ON TUESDAY WITH ITS LOW PLACEMENT, AND ALSO THE NAM
APPEARING TO BE TOO DEEP. WILL PREFER A GENERAL MODEL BLEND
THROUGH 48 HOURS, AND THEN LEAN TOWARD A BLEND OF THE 00Z GFS,
YESTERDAY'S 12Z ECMWF AND INCORPORATING YESTERDAY'S 12Z ECENS MEAN.
..UPPER LOW APPROACHING THE WEST COAST BY SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS/18Z GEFS MEAN AND 12Z ECENS MEAN
CONFIDENCE: AVERAGE
ON SUNDAY, A NEW CLOSED LOW WILL BE EVOLVING OFFSHORE OF THE WEST
COAST, INCLUDING A SEPARATE CENTER OVER THE NORTHWEST U.S. WHICH
BREAKS AWAY AND PIVOTS OFFSHORE THE WEST COAST. THERE WILL BE SOME
BINARY INTERACTION BETWEEN THE TWO CENTERS, WITH THE GUIDANCE
FAVORING A CONSOLIDATION OF THE TWO SYSTEMS OFFSHORE OF CALIFORNIA
BY MONDAY EVENING. THE SYSTEM IS EXPECTED TO DROP SOUTH THROUGH
TUESDAY AND THEN BEGIN TO ADVANCE SOUTHEAST TOWARD SOUTHERN
CALIFORNIA BY EARLY WEDNESDAY. THE 00Z GUIDANCE HAS COME INTO
BETTER AGREEMENT IN TAKING THE CLOSED LOW A BIT FARTHER SOUTH
COMPARED TO YESTERDAY'S 12Z/18Z CYCLES BEFORE THE TURN OFF TO THE
SOUTHEAST LATER IN THE PERIOD. THE 00Z GFS AND 00Z GEFS MEAN ARE A
LITTLE NORTHEAST OF THE OVERALL MODEL CONSENSUS BY THE END OF THE
PERIOD. YESTERDAY'S 12Z ECENS MEAN THOUGH DOES STILL FAVOR THE
LATEST GFS/GEFS CAMP, AND SO THERE IS A TAD OF AN UPTICK IN
UNCERTAINTY REGARDING THE CLOSED LOW PLACEMENT AS THE 00Z
UKMET/CMC AND 00Z NAM SOLUTIONS ARE A LITTLE BIT FARTHER SOUTH.
FOR NOW, WILL MAINTAIN THE EARLIER PREFERENCE GIVEN THE BREADTH OF
ENSEMBLE AGREEMENT.
..SHORTWAVE APPROACHING THE NORTHERN PLAINS/UPPER MIDWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS BRING A NORTHERN STREAM SHORTWAVE SOUTHEAST ACROSS
PORTIONS OF THE NORTHERN PLAINS AND UPPER MIDWEST BY MONDAY AND
THEN DROP IT DOWN ACROSS THE OH VALLEY THROUGH TUESDAY. THE
GUIDANCE IS IN GOOD AGREEMENT THROUGH THE PERIOD NOW AS THE 00Z
UKMET HAS SLOWED ITS PROGRESSION AND IS NOW IN LINE WITH THE MODEL
CONSENSUS. A GENERAL MODEL BLEND WILL BE PREFERRED THROUGH THE
PERIOD AS A RESULT.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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