209
FXUS10 KWNH 101640
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1239 PM EDT SUN MAY 10 2020
VALID MAY 10/1200 UTC THRU MAY 14/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SURFACE LOW MOVING FROM GREAT LAKES TO NEW ENGLAND THROUGH
TUESDAY...
...ENERGY AMPLIFYING FROM THE OH VALLEY TO THE NORTHEAST MON AND
TUES...
...SHORTWAVE MOVING ACROSS THE GREAT LAKES AND NORTHEAST TUESDAY
AND WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12.12Z; FOLLOWED BY A
ECMWF/ECENS BLEND
CONFIDENCE: AVERAGE
LARGE CYCLONIC FLOW WILL PERSIST OVER THE GREAT LAKES AND EASTERN
US THROUGH EARLY NEXT WEEK WITH LARGE HEIGHT ANOMALIES CENTERED
OVER THE HUDSON BAY REGION. A PAIR OF COMPACT SHORTWAVES WILL WORK
THROUGH BASE OF THE LARGE SCALE CLOSED LOW, THE FIRST OF WHICH
MOVES FROM THE UPPER MISSISSIPPI RIVER VALLEY TODAY TOWARD THE
NORTHEAST EARLY NEXT WEEK. A DEEPENING SURFACE LOW WILL TRACK FROM
NEAR CHICAGO TO THE GULF OF MAINE. THROUGH ABOUT 36 HOURS, THE LOW
TRACK AND DEPTH IS WELL AGREED UPON BY THE LATEST GUIDANCE BUT
THEN DIVERGES AS THE SYSTEM EXITS THE COAST OFF MAINE. THE GFS HAS
A NORTHERN TRACK AND THE NAM ALSO IS ON THE NORTHERN SIDE OF THE
SPREAD. THE NON-NCEP GUIDANCE SHOWS FAIRLY GOOD CLUSTERING ON THE
SOUTHERN SIDE OF THE SPREAD. LOOKING AT THE ENSEMBLES, THE
ECMWF/ECENS ARE NEARLY IDENTICAL WHILE THE GEFS MEAN LEANS TOWARD
THE ECMWF/ECENS SOLUTION, PUTTING THE DETERMINISTIC GFS AS THE
OUTLIER. FOR THIS REASON, A NON-GFS SOLUTION IS RECOMMENDED AFTER
12.12Z.
A SECONDARY, COMPACT SHORTWAVE IS THEN FORECAST TO WRAP BEHIND THE
INITIAL SYSTEM OVER THE NORTHERN/INTERIOR NEW ENGLAND STATES
TUESDAY/TUESDAY NIGHT. HERE, MODEL AGREEMENT IS RELATIVELY STABLE,
THOUGH THE CMC AND UKMET SEEM TO HAVE SOME TIMING/DEPTH ISSUES.
THE UKMET IS ON THE FASTER SIDE OF THE MODEL GUIDANCE WHILE THE
CMC IS A BIT TOO DEEP AS THE SHORTWAVE PIVOTS OVER NEW ENGLAND.
FOR THESE REASONS, A GENERAL MODEL BLEND SHOULD BE SUFFICIENT
THROUGH ABOUT 12.12Z BUT BEYOND THAT, GIVEN THE ISSUES WITH THE
INITIAL AND SECONDARY SHORTWAVES/LOWS, A BLEND UTILIZING PRIMARILY
THE ECMWF/ECENS MEAN IS PREFERRED.
..SHORTWAVE ENERGY CROSSING THE SOUTHWEST ON SUNDAY
..ENERGY SHEARING ACROSS THE SOUTHERN PLAINS BY TUE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
A SUBTLE SHORTWAVE WILL MOVE THROUGH PORTIONS OF THE DESERT
SOUTHWEST TODAY BEFORE CROSSING INTO THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY EARLY NEXT WEEK. IN THE LARGE SCALE SENSE,
THERE ARE VERY LITTLE DIFFERENCES SEEN IN THE LATEST MODEL
GUIDANCE AND A GENERAL MODEL BLEND SHOULD MORE THAN SUFFICE FOR
MASS FIELD PURPOSES. AS THE SYSTEM EJECTS INTO THE PLAINS, THERE
ARE SOME MAGNITUDE DIFFERENCES IN QPF BUT THESE SHOULD BE RESOLVED
ON A SMALLER SCALE THAN THE SYNOPTIC PATTERN.
...UPPER TROUGH/CLOSED LOW LIFTING ALONG THE NORTHWEST COAST
MON-WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12.12Z; NON-NAM THEREAFTER
CONFIDENCE: AVERAGE
A LONGWAVE TROUGH AND CLOSED LOW APPROACHES THE PACIFIC NORTHWEST
EARLY NEXT WEEK. AS THE SYSTEM APPROACHES THE COAST, IT WILL
SLOW/STALL THANKS TO STUBBORN RIDGING INLAND. THE CLOSED LOW WILL
THEN WOBBLE/MEANDER THROUGH THE END OF THE PERIOD. PIECES OF THE
ENERGY WILL SEPARATE AND MOVE INLAND, INTERACTING WITH ANOTHER
PIECE OF SHORTWAVE ENERGY OVER THE SOUTHERN CANADIAN ROCKIES.
THROUGH ABOUT 48 HOURS, A GENERAL MODEL BLEND SHOULD BE SUFFICIENT
AS THERE IS LITTLE SPREAD SEEN IN THE LATEST GUIDANCE. BEYOND THAT
TIME FRAME, THE NAM BECOMES LESS USABLE AS IT APPEARS TO BE TOO
QUICK TO ABSORB MORE OF THE ENERGY INTO THE ROCKIES SYSTEM. THE
MORE RELIABLE ECMWF/GFS/UKMET IN THE 48-84 HOUR RANGE SHOW THE
CLOSED LOW LINGERING LONGER, WHICH FITS THE PATTERN AND
TELECONNECTIONS.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
TAYLOR
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