042
FXUS10 KWNH 110441
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1241 AM EDT MON MAY 11 2020
VALID MAY 11/0000 UTC THRU MAY 14/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z 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 MONDAY
AND TUESDAY...
...SHORTWAVE MOVING ACROSS THE GREAT LAKES AND NORTHEAST TUESDAY
AND WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12.12Z; FOLLOWED BY A
NON-UKMET BLEND
CONFIDENCE: AVERAGE
LARGE CYCLONIC FLOW WILL PERSIST OVER THE GREAT LAKES AND EASTERN
US THROUGH EARLY THIS 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 GREAT LAKES TODAY INTO THE NORTHEAST ON MONDAY. A
DEEPENING SURFACE LOW WILL TRACK FROM NEAR THE LOWER LAKES TO THE
GULF OF MAINE. THE LOW TRACK AND DEPTH IS WELL AGREED UPON BY THE
LATEST GUIDANCE THROUGH EARLY TUESDAY AS THE SYSTEM TRACKS
NORTHEAST FROM THE GULF OF MAINE INTO THE CANADIAN MARITIMES. IN
COMPARISON TO THEIR 12Z RUNS, BOTH THE NAM AND GFS ARE SLOWER WITH
THE TRACK OF THE LOW AS IT MOVES THROUGH THE GULF OF MAINE -
PUTTING THEM IN BETTER AGREEMENT WITH THE 12Z ECMWF AND EC
ENSEMBLE MEAN.
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 12Z UKMET STILL SEEMS TO HAVE SOME TIMING ISSUES -
PARTICULARLY AS THE SYSTEM MOVES ACROSS NEW ENGLAND TUESDAY NIGHT.
..SHORTWAVE ENERGY CROSSING THE SOUTHWEST ON SUNDAY
..ENERGY SHEARING ACROSS THE SOUTHERN PLAINS BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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
MONDAY-WEDNESDAY...
...UPPER LOW CLOSING OFF OVER WESTERN CANADA ON TUESDAY BEFORE
MOVING EAST THROUGH THE CANADIAN PRAIRIE WEDNESDAY-THURSDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12.12Z; NON-NAM THEREAFTER
CONFIDENCE: AVERAGE
A LONGWAVE TROUGH AND CLOSED LOW APPROACHES THE PACIFIC NORTHWEST
EARLY IN THE WEEK. AS THE SYSTEM APPROACHES THE COAST, IT WILL
SLOW/STALL THANKS TO PERSISTENT RIDGING INLAND. THE CLOSED LOW
WILL THEN WOBBLE/MEANDER THROUGH THE END OF THE PERIOD. PIECES OF
ENERGY WILL SEPARATE AND MOVE INLAND, INTERACTING WITH ANOTHER
PIECE OF SHORTWAVE ENERGY/CLOSED LOW OVER THE SOUTHERN CANADIAN
ROCKIES. INTO EARLY WEDNESDAY, A GENERAL MODEL BLEND SHOULD BE
SUFFICIENT AS THERE IS LITTLE SPREAD SEEN IN THE LATEST GUIDANCE.
BEYOND THAT TIME FRAME, THE NAM REMAINS THE RELATIVE OUTLIER -
INDICATING GREATER INTERACTION BETWEEN THE PACIFIC AND CANADIAN
SYSTEMS ON WEDNESDAY, WITH THE CANADIAN LOW THEN SLOWER TO MOVE
EAST OF THE SOUTHERN CANADIAN ROCKIES INTO THE CANADIAN PRAIRIE
AND NORTHERN GREAT PLAINS WEDNESDAY NIGHT/THURSDAY MORNING.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
PEREIRA/TAYLOR
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