515
FXUS10 KWNH 241843
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
241 PM EDT WED JUN 24 2020
VALID JUN 24/1200 UTC THRU JUN 28/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER ONTARIO/QUEBEC
TROUGH CROSSING THE EASTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE UPPER-LEVEL LOW IN PLACE OVER THE NORTHERN GREAT LAKES IS
EXPECTED TO LIFT NORTH/NORTHEASTWARD OVER THE NEXT FEW DAYS WHILE
THERE WILL BE SOME SOUTHWARD EXPANSION ON THE LONGWAVE TROUGH OVER
THE EASTERN U.S., WHICH PUSHES A COLD FRONT THROUGH MUCH OF THE
MID-ATLANTIC AND NEW ENGLAND BEFORE WASHING OUT OVER THE
SOUTHEAST. FROM A SYNOPTIC POINT OF VIEW, MASS FIELDS ARE IN GOOD
SHAPE IN THE REGION AND A GENERAL MODEL BLEND IS PREFERRED.
SHORTWAVE CROSSING THE PACIFIC NORTHWEST AND PLAINS/MIDWEST
ENERGY DIGGING INTO THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND...NORTHERN STREAM
NON-CMC BLEND...SOUTHERN STREAM
CONFIDENCE: ABOVE AVERAGE
THE LATEST GUIDANCE CONTINUES TO ADVERTISE A SHORTWAVE TROUGH
CROSSING THE PACIFIC NORTHWEST THROUGH TONIGHT AND THEN ADVANCING
PROGRESSIVELY DOWNSTREAM ACROSS THE CENTRAL/NORTHERN ROCKIES GOING
THROUGH THURSDAY. AS THIS IS OCCURRING, SOME OF THE ENERGY WILL BE
SEPARATING OUT AND DIGGING FARTHER SOUTH INTO THE SOUTHWEST. GOING
THROUGH FRIDAY AND SATURDAY, THE NORTHERN PORTION OF THE ORIGINAL
TROUGH WILL EJECT OUT ACROSS THE NORTHERN PLAINS AND UPPER
MIDWEST, WITH THE GUIDANCE FAVORING A SOUTHERN STREAM TROUGH
LINGERING NEAR THE FOUR CORNERS REGION. WITH THE INITIAL SURGE OF
THE NORTHERN STREAM PORTION OF THE TROUGH, THE MODELS ARE IN GOOD
AGREEMENT ALTHOUGH THE 12Z UKMET SHOWS A SLIGHTLY MORE PROGRESSIVE
AND WEAKER TROUGH COMPARED TO THE OTHER MODELS BY THE END OF THE
PERIOD AS THE ENERGY CROSSES THE GREAT LAKES REGION. WILL PREFER A
NON-UKMET BLEND AS A RESULT WITH THIS NORTHERN STREAM TROUGH
EVOLUTION.
WITH THE SOUTHERN STREAM ENERGY, THE 12Z CMC IS A BIT WEAKER AND
MORE PROGRESSIVE WITH THE ENERGY COMPARED TO A REASONABLY
WELL-CLUSTERED SET OF MODELS OTHERWISE WHICH KEEP MORE ENERGY A
TAD FARTHER BACK TO THE WEST. THIS INCLUDES THE 12Z ECMWF WHICH
TRENDED A TAD FARTHER EAST AND IN LINE WITH THE 12Z NAM, 12Z GFS
AND 12Z UKMET. SO, A NON-CMC BLEND WILL BE PREFERRED AT THIS POINT
WITH THE SOUTHERN STREAM ENERGY.
STRONG SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST THIS WEEKEND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: AVERAGE
A STRONG SHORTWAVE TROUGH FROM THE GULF OF ALASKA IS FORECAST TO
DROP SOUTH ALONG THE BRITISH COLUMBIA COAST AND ARRIVE ACROSS THE
PACIFIC NORTHWEST BY SATURDAY MORNING. WITH THE INITIAL SURGE OF
HEIGHT FALLS, THE 12Z GFS IS NOW OVERALL THE MOST PROGRESSIVE AS
THE MODESTLY SLOWER 12Z NAM IS GETTING BETTER CLUSTERING/SUPPORT
FROM THE 12Z CMC, 12Z UKMET AND 12Z ECMWF. THE GFS IS MORE OUT OF
TOLERANCE ALSO WITH ADDITIONAL JET ENERGY DIGGING SOUTH LATE
SATURDAY ALONG THE BRITISH COLUMBIA COAST. THERE IS SOME SUPPORT
FOR THE GFS THOUGH FROM THE LATEST 12Z GEFS MEAN. HOWEVER, THE 00Z
ECENS MEAN FAVORS THE FULL NON-NCEP SUITE OF GUIDANCE AND THE NAM.
SO, FOR NOW A NON-GFS BLEND WILL BE PREFERRED.
LOWER MS VALLEY AND GULF COAST STATES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
WEAK FLOW ALOFT WITH PIECES OF SHORTWAVE ENERGY BECOMING REMOVED
FROM THE WESTERLIES WILL DRIFT OVER THE TEXAS GULF COAST AND LOWER
MS VALLEY. THE MODELS ARE IN BETTER AGREEMENT TODAY WITH GRADUALLY
TAKING SOME OF THIS OFF TO THE EAST-NORTHEAST AND SHEARING IT OUT
ACROSS THE GULF COAST STATES OVER THE NEXT 2 TO 3 DAYS. HOWEVER,
THE MODELS ALL AGREE IN MAINTAINING A BROAD MID-LEVEL WEAKNESS
OVER TEXAS THROUGH THE PERIOD. THE 12Z NON-NCEP SUITE OF GUIDANCE
TRENDED TOWARD THE SLOWER NAM/GFS AND HREF CLUSTERING OF SOLUTIONS
WITH THE INDIVIDUAL VORTS, AND BASED ON THE BETTER AGREEMENT, A
GENERAL MODEL BLEND WILL NOW BE PREFERRED.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page